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Post by newey on Jul 24, 2013 6:28:36 GMT -5
While a 75-watt powered mixer with the little satellite speakers does sound like a good option, it's still $450 and has much more capability (i.e., 4 channels)than you will likely ever use. If it's just for home and/or small room use, I think you could find cheaper options.
And, you're unlikely to be using all 40 watts of the Hot Rod (or anything close to that) for the mag channel, so a wattage mismatch won't really be a problem. Also, while you're speaking of "high end" and "low end" (and I understand what you mean), let's keep in mind that this is a figure of speech. There's no crossover to separate frequencies, so each channel still has to reproduce the full spectrum.
A small keyboard amp could be a lot cheaper although it would lack the cool satellite speakers. It probably won't have onboard reverb, either, but a pedal could supply that. Most of these amps have a co-axial speaker setup for the highs/lows and an XLR input for a mic. They are designed for a "clean" sound like a PA. Something like a Roland Cube 30 or a Peavey KB-2 would run you about half of the Behringer PA's cost. I also often see these things used on Ebay for much less.
Or perhaps a dedicated acoustic amp. These often have a mic channel as well.
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Post by ux4484 on Jul 24, 2013 8:55:45 GMT -5
Too bad Musicians Friend doesn't ship to the Island, here's a cheap, portable, and flexible option   (no reverb though)  Gem Sound |
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Post by JohnH on Jul 24, 2013 15:37:43 GMT -5
Ive bought a few bits of Behringer gear, and it sounds good and is well designed. But more than half of it has had to be returned due to defects. This included a guitar amp for my son, and of our two powered PA speakers, one had to go back due to noise, then the next one had to go back again until we finally got a good pair. I really like these speakers (now that they were swapped) and they have been good for 4 years now. They are 15" active units. My advice if you go with Behringer is not to buy from anywhere where you cant easily take things back, and test it all out before putting the money down. My several problems could have been caught in the shop if I had been more careful.
I have a small xenix mixer, which has been fine.
Starting from scratch with your application, Id go an unpowered mixer and active speakers - probably 12". I got a great recent 16 channel Soundcraft mixer from ebay for about $200, and there are 8 channel models with fx too.
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Post by JohnH on Jul 24, 2013 17:23:18 GMT -5
With further thought..definately the unpowered mixer, with some fx say 4 mic inputs plus line-ins and usb out. That would be a thougherly useful item for your perfornances and also writing/recording at home. The extra inputs give you versatility when you meet up with other players. Your current monitors would be a start, and you will know whether they are adequate for say, an intimate restuarant. When more is needed, two lines from the mixer can go to a couple of active speakers hired for the night, or, straight into a house pa system at a pub.
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Post by 4real on Jul 24, 2013 20:02:33 GMT -5
Well, I tried the monitors thing and though can sound good, not loud enough or practical. The mixer is a good one. If one is playing or having a 'jam' which has happened and might do again, multiple inputs, the ability to use a mic, recording more than a stereo pair that kind of thing. As far as any possibility of 'gigs' as such, I've been asked to play at things like art gallery openings and such (don't ahve the repetoire yet" and that kind of thing.
I have a Roland GA60 (which is like a jazz chorus, single 12" aluminium domed(or with extention 15") with graphic and reverb which is very clean and clear and loud)but I've inevitably found that playing through those kinds of traditional 'boxes' to be a bit unsatisfactory from both a performer but listener perspective...it's very directional and seems a bit 'distant' from the performance if that makes sense.
The fender is beautiful (when it's working though quite heavy and delicate in a way) especially for electric guitar...perhaps it could be augmented with a tweeter or something...
Both these guitar amps and a few other options are single channel so, at least some kind of mixer would be required to play a stereo guitar that is active and passive and require different EQ's and such.
So...something small and can be lifted high and sound 'wide' seems to make sense. Also to be able to play MP3's and such or even as a home sound system I guess would be useful. I also have a nice condenser mic so would need phantom power. There are some nice small acoustic amps, but the good stuff is not cheap and specialised to do that 'one thing' it seems. Loud, anone sitting close will get blasted as well, if the player is close you get all kinds of feedback problems as well.
This is kind of an extension of the kinds of things I did with the last project with a kindof surround sound and can do it with the two guitar amplifiers optimised for the individual pickup systems and spread wide, the sound does not need to be particularly loud, but the experience is kind of like being 'surrounded' by the sound rather than it 'blasting' at you and is quite a different experience.
A lot of the acoustic sound is in the high end and suspect that is why many are disappointed by piezo equiped guitars through a single guitar amp...either there is a compromise andthe piezos never sound convincing, or the 'electric sound' is too comprimised by whishing to sound good for both. The idea of using the fender as well, would be to give it the bottom end and warmth perhaps and compensate for some kind of ultra-compact speakers...even if capable of 2x75 or 150 watts of power as in this example.
A stand alone mixer tends to ahve more features and versitility, but then, one needs and amp and speakers or powered speakers andthe entire system is way over the top and take up a lot of space an not so portable.
I looked at adopting something like a surround sound system to create this kind of 'effect' as they can be quite loud and fill a room, not sure how it would hold up and still require a mixer of some type.
So, thanks for the suggestions and will continue to think aobut it and take ideas. No, overseas shipping is too much and generally they don't ship if there are suppliers. Behringer is cheap and ahve heard of a lot of problems and with returns, 'cranbourne music' isthe biggest and nearest place and now not stocking them in favour of Mackie stuff. Not a good sign, though I've read a lot of good reviews, there do seem to be problems and hard to get, try and certainly return from out here.
On the 'high end'...I think you get it...it is that the acoustic guitar contains a heap of higher harmonics and never sounds right through a guitar amp that is optimised for 'midrange'...expecting one speaker to cope with these kinds of signals convincingly.
I'm really trying to get a really good quality sound, not just a 'louder sound' and a lot of this I feel is going to ahve to rely on the amplifier, mixer and format of things perhaps...it's a little hard to say...hmmm
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Post by sumgai on Jul 25, 2013 13:03:00 GMT -5
4, Sounds to me like your better bet might be a full-fledged system such as Fender Passport or similar offerings from Yahama and others. While expensive as new, used gear is blessedly inexpensive, as witness this eBay offering: www.ebay.com/itm/Fender-Passport-500-Pro-Portable-PA-System-500-Watts-/231021157654That's certainly more power and probably more utility than you'll likely need as a one-man-band, but it's an example of pricing - 50 USD as of the time of this writing. Not bad, I'd say. Coupled with either of your guitar amps, something like this should be quick to set up/tear down, fairly easy on the back muscles, and even easier on the wallet. As for sound quality, that's something for you to determine, of course, but for most "non-loud" applications, rigs like this are quite acceptable. After all, in any public setting, absolutely the highest fidelity possible is a non-starter... folks are doing other things besides listening to you, and even then, it's not with the intent of determining if you "sound good", it's only as a distraction. An enjoyable distraction, to be sure, but nonetheless.... For recording purposes, I'm sure you've already got just about everything you need to make that happen, but a hardware mixer does go a long way towards making that easier, at least in my mind. Some users do like doing everything in software, even mixing for live performances, and I can't say that's bad, simply that's not the way I'd prefer to do it. As to speakers, I can only repeat what gumbo says - "I'm too damned old to be lugging these heavy things up and down stairs, and onto stages!" Keeping it simple is really the way to go, so you may want to choose between a light (plastic shell) powered speaker and a setup where they are separate components. In other words, where is the weight concentrated, so as to make things the most difficult/tiring for you? And can you adjust that to something more acceptable, that's the other side of that question. HTH! sumgai |
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Post by 4real on Jul 25, 2013 14:49:23 GMT -5
With further thought..definately the unpowered mixer, with some fx say 4 mic inputs plus line-ins and usb out. That would be a thougherly useful item for your perfornances and also writing/recording at home. The extra inputs give you versatility when you meet up with other players. Your current monitors would be a start, and you will know whether they are adequate for say, an intimate restuarant. When more is needed, two lines from the mixer can go to a couple of active speakers hired for the night, or, straight into a house pa system at a pub. I suspect you might be right, which was the original thought, but negative on the monitors...perhaps some DIY solution...continue thinking... Actually, didn't you add a tweeter into a guitar amp for your piezo electric...are there details on that? Well, everything is cheaper in the states it seems...this eBay special sounds like it fell off a truck and may not be a bargain, especially with a blown speaker and who knows what else is rattling inside the case and more...getting stuff out here is not so easy and returns even harder... The thing is the effect of a single amp loud enough to be heard equally throught a room tends to be way too loud when you get close to the source/performer, while multiple head hight small monitors can give a more ambient effect, be far less intrusive and smaller and not as loud for a similar effect. And yes, it is hard to get adequate fidelity and may seem a bit of an 'ask', but if the electric side of the instrument is a part of the 'sound' of it, it's not just a PA or being heard, any more than the amplifer is in playing the electric guitar, it is a part of the instrument. I appreciate the idea of something very simple and there is conventional solutions, some I could 'get by with' but not at all ideal and still heft quite a bit of weight. There are some moves in this direction of late, like the Bose towers or this offering for this application and aims from fishman... www.musiciansfriend.com/amplifiers-effects/fishman-sa220-solo-performance-system-acoustic-guitar-combo-amp And yes, ideally it would work well without the amp too, the example I was thinking of at 150watts packs up into a suitcase one can carry in one hand...it's only got 4"" woofers and 1" tweeters...So I was thinking of 'ultra-comapct' for a small room at most, so even smaller than a 'passport' kind of thing ideally. I agree, even smaller, easier and more compact than this kind of entire PA, it is not taking the demands of a 'band' ... Originally I was thinking something very small and of a similar kind of power with a nice versitile mixer as the front end and perhaps that is the way to go... So, perhaps thoughts as to how to do powered small full range powered speakers that could be mounted on something like mic stands or similar things I could make. Most places I'd be considering, and even at home, I dont ahve the room for these kinds of massive speakers and the added big stands required to get the effect having the sound source well off the ground. The above fishman system for instance has six small speakers and a tweeter and provides monitoring as well as wide dispersal, though only 2 channels... So, looking for a similar solution I guess and the format is not likely to be met, iMo with a conventional approach. Smaller the better and so will consider options... The mixer idea makes sense as it would be useful and required and so only require small powered speakers for the kinds of things I am considering and could be expaned, though not so likely to be necessary I suspect. The smaller the better as a lot of the kinds of places want unobtrusive and lack of adequate amplification solutions is a disinsentive to taking up offers as many people ahve the expectation that one can get an adequate sound out of the acoustic guitar fingerpiched on it's own. The reality is that a lot of 'techniques' require amplification to work at all, or at least further than sitting directly in front of the instrument...and there is generally little room at all for anything much bigger than a guitar amp... Anyone got ideas for perhaps making powered small monitors of some kind? |
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Post by newey on Jul 25, 2013 23:18:04 GMT -5
4real-
You earlier mentioned a DIY project using a surround sound disc player/amp, and that might be a low-budget way to go, or perhaps just to test concepts. I'm thinking of the systems marketed for home theater use, these run new about $150 and a good deal less if used.
Since the 7.1 systems have come on the market, I see good used 5.1 systems quite often at garage sales and the like. These will have small satellite speakers, maybe even with stands supplied, and you wouldn't have to use all the channels, of course. The amp unit is another piece to carry, but these are fairly light and give you a disc player as well.
Maybe use a small portable mixer at the front end, it could be velcroed to the top of the amp/disc player unit and so transported as a piece.
The sound quality won't make anyone forget their MacIntosh tube amp and Theil speakers, but it's probably on a par with a PA system. And, even if it's not perfectly to your liking, it may allow you to test out things like speaker placement. Then flip it to get some of your money back if desired.
I'll bet you can find a suitable mixer, used, for $50 or so, and maybe the same for a used surround sound.
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Post by 4real on Jul 25, 2013 23:47:25 GMT -5
YES... As it happens I ahve a cheapish 5.1 surround system that the CD changer has broken and hardly used...so was thinking this might be the way to go, but ahving doubts about how it might stand up to musical instrument going through it...but yes, that kind of thing. I could stack two satelite speakers together on stands, have the centre and powered sub with a mixer in a box for rooms for other stuff and cables, so it could all pack into a special box (on wheels perhaps)... The doubts are how much the speakers and such can take but it is not as if I want something super loud, just loud enough...add a guitar amp for more oomph perhaps. There are some great mixers aobut and certainly more featured than that mini PA and also compact...something with compression might help tame 'spickes' that might kill the speakers... And as you say, will at least give the 'idea' and cheap... That would mean as john suggests, one could put more into a stand alone mixer with fuller features and potential for things like recording...which was kind of my original intention pretty much...anc ould be sued with bigger powered speakers should that ever be required, though I some how doubt that would be necessary. I even got a couple of old surround sound stands that are very solid at the sunday market recently for $10 the pair recently (been doing work at the sunday market as my GF has a stall there and would be an ideal venue in the summer for something, as another example. There are lots of places like 'wineries' and cafe's and such, but there is not a lot of room for things like PA's or the like, but do require a pretty decent sound. Added bonus would be to use it as a loud MP3 player while doing housework. The Behringer Xenyix mixers are the kind of thing and see there have them on special lately...something like the Q1204USB has a whole host of features that would be useful in any context and even operates as a USB sound interface... www.soundcorp.com.au/behringer-12-input-2-2-bus-mixer-1204usb.htmlor even better and 'rack mountable'... www.soundcorp.com.au/behringer-ub1622fx-pro-free-shipping.htmlSuch mixers have phantom power and compressors and good EQ's...and would I suspect make an awesome headphone amp as well for 'practice'... So...what do you think...how much can a surround system take before 'failure'? |
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Post by sumgai on Jul 26, 2013 0:21:21 GMT -5
4, Sorry, didn't read far enough to see that part about the blown woofer, that's certainly a deal killer for 99.9% of all potential buyers. And yes, it does cost about as much as a semester of college education to ship anything from the US to you, but.... I was merely pointing out the viability of seeking out sources of used (or even new, sometimes) gear, but I was also assuming that you'd refine your search parameters and keep things "local" - no sense in looking 'offshore' if there's no saving after shipping. As to DIY..... here's an idea: Do as JohnH does, and pickup a couple of little Crate amps, the ones that are Class D, 150 watts, and weigh about 5 pounds. You can then choose to pack them separately, or build them into separate, home-built speaker cabints. Ask John for more details on that score, but the bottom line is, for the price you can't beat them. DIY is arguably the better way to go, most of the time, but there are times when it doesn't make sense to try and re-invent the wheel. Though I have to admit, I like that Behringer mixer you picked out. A couple of lightweight speakers and you're good to go. Keeping it simple by leaving the speakers on the floor actually helps to keep the 'apparent' volume down to a managable level, as the bodies themselves will be soaking up some of that awesomeness coming out of your rig. Another trick, particularly with your guitar amp, is to turn it facing the wall, or better yet, facing at an angle into the corner. By that I mean, it's loading the corner which in turn spreads the sound out even further, and at the same time it's sort of balancing or evening out the general frequency spectrum. In many rooms it works a treat, in some few it's a ho-hum, and once in awhile it actually makes things worse. Experimentation is the keyword there. On another topic, quite related.... I need to remind you that your mixer, and most of them on the market, does not support 'bi-amping'. If you want true separation of highs and lows through disparate speaker sets, that's gonna require yet another piece of gear, to wit: a cross-over. While not necessarily expensive, such will add yet another bit of weight to the kit, and require a bit more time for setting up. However, if your intention is to use the guitar mag pups primarily for "deep" voicings, and run that strictly through the guitar amp, and then use the piezo for "added defintion" type tonality, with that running through the PA, then I think your musings are headed in the right direction. HTH sumgai |
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Post by 4real on Jul 26, 2013 5:31:28 GMT -5
All good ideas and yes, kind of the kind of thing I am thinking of. I realize that you are not going to get 'bi-amping' but the guitar amp or different speakers have a different kind of natural crossover...I often use a 15" bass bax with my 12" combo, especially in the old days with the roland and that spreads the sound and sounds great with Bass giving definition and 'thump'. I'd likely take a bit of a line out of the amp back to the speaker, though that is just an idea as a really good mixer may well be enoguh and keep things simple with the "PA' type of thing.
I'm not sure you can even get crate out here, have not seen or heard of them for a while and not that model, will await comment. I considered somethinhg like that, say two small guitar amps, even DJ speakers perhaps withh horns that I've seen about fairly cheap but suspect they may ahve that guitar amp bias and would perhaps require tweeters or something, will wait for further comment...
I think though that kind of thing is in the right direction...
It's really about a 'spread' of sound and giving the guitar dimension with the piezo doing what it does best with high end definition and teh mag giving the 'depth' and longer sustain and harmonics that are often lost with the piezos that don't react as well to those very high frequencies where the string is vibrating a lot less. I suspect that is why that people favour dual or more systems in a lot of cases. Bear in mind, that I don't aspire to just 'strum' the acoustic but to play separate lines with fingerpicking. Part of teh problem is a lot of playing by necesity is very 'soft' acoustically and I tend to play lightly anyway, the beauty of the electric guitar is that one can get any volume one wants.
A more 'advanced and featured' mixer like these have compression and good eq control and extra effects and loop capabilities and versitility as a sound console/interface to the computer ... I'll be hoping to sell of a bunch of stuff to pay for it...anyone want some vintage effects?
I like the idea of a built in cabinet to keep things safe and storage on wheels perhaps, and very small satelite speakers with a sub woofer or something may be the go...
Anythoughts on how a surround system would fare under musical instrument loads?
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Post by JohnH on Jul 26, 2013 7:38:43 GMT -5
As to DIY..... here's an idea: Do as JohnH does, and pickup a couple of little Crate amps, the ones that are Class D, 150 watts, and weigh about 5 pounds. sumgai Referring to one of these:  It is a handy little amp. It has a reasonable mono guitar preamp, then a stereo power amp stage, that can do 2x75w into 4 ohms, or bridged with 150W into 8 ohms. It certainly has ample power for what you need. Ive had it as a small PA, and also running up to 4 foldback wedges for vocal monitoring. very handy ins and outs, including direct input to the two power amps. You can configure it to have one taking a line-in from a mixer, and the other running its own guitar preamp. I bought it here in Aus, but a few years ago and they haven't been made since about 2007. They come up on ebay from time to time. Its a shame theres nothing quite similar now. I think there were some failures, but mine is good. It's the 'little amp that could' If you did consider one, you could buy from the US since they are light, and run off any voltage 100 to 240 using a kettle cord. |
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Post by ux4484 on Jul 26, 2013 10:17:21 GMT -5
Crate just has poor marketing, when those first came out in the US, they were in the $250-300 range. They didn't sell ANY. MF and GF fire saled them for $150, and then $100 and they sold like hotcakes. They are nice clean amps, I saw one guy using it as his bass amp, very usable tone.
They often sell for more than the fire sale price on eBay.
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Post by 4real on Jul 26, 2013 15:28:57 GMT -5
Very cute amps...a few other amps have been made small as I recall but never worked out so well. Tiny amps are becoming more common in the acoustic world too....perhaps electric guitar players just like giant heavy boxes or soemthing.
There would still be the problem of boxes...seen some powered DJ boxes about fairly cheap but I wonder how well they would cope with musical instruments or sound...
I am feeling more confident of the mixer route though...
And trying to go very compact makes a lot of sense and will continue to go down that route...even with this kind of amp, there is still the problem of speakers...
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Post by 4real on Aug 1, 2013 14:59:16 GMT -5
Still considering options for amplifying. One cool project JohnH did was add piezos to a 12inch cab and I do ahve a 12" chrome dome, very clean Roland GA60 combo that has been ubur reliable over the years. It ahs a 6 band graphic and if I pull the middle, 2.5kHz and 1.5kHz down a bit it takes out a bit of that midrange gutiar amp sound...adding piezos to it would be fairly 'invisible' and definitely something to consider... guitarnuts2.proboards.com/thread/3887/speaker-cab-electric-acoustic This is something others interested in piezo guitars might need to consider too as the same problems exist trying to run an electric and piezo sounds and expecting the best of both worlds out of the amps. That still leaves the problem of needing more than one input and routing and tone shaping, so a mixer would also be required...so looking at eBay for a cheaper option...hit a roo and without a car and extra life expense at the moment so better be careful with the money...besides a move is on the horizon and a new project soon is probably not the greatest idea! The guitar is still fine though, have not needed to change the strings but looking forward to tinkering with it. The JLD has kept the top completely flat and no problems with it and everything settled in. The top stabalisation really is a good thing and has not adversely affected the natural sound of the guitar and helps with tuning stability when altering things. The tuners are still fantastic, very stable in the tuning and easy to changetunings without too much fear of the strings needing to settle, so all good there. |
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Post by JohnH on Aug 1, 2013 17:10:36 GMT -5
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Post by 4real on Aug 1, 2013 17:44:05 GMT -5
Thanks John...will check it out...i take it the tweeters were these...$10 each www.jaycar.com.au/productView.asp?ID=CT1930Could you sketch up a wiring diagram do you think, the description of 'series/parallel wasn't completely clear. I checked out my roland combo and there will be room on the baffle and hidden behind the grill. Do you think it was worth the angling of the piezos, are they that directional? |
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Post by JohnH on Aug 2, 2013 3:41:27 GMT -5
Thats the piezo. They seem to have gone up a couple of $.
I angled them just by blocking the mounting screws. . When you are off axis, its better to hear just one so they dont interfere. I didnt really test it though. If you try this, you can just place them on top of the amp to test.
My wiring was resistor, piezo, piezo all in series, and that chain wired across the main speaker. Per the article, the resistor would be 100 ohms for this. That would give a full range response with a roll off above audio range. The descrjption suggests that these units each are like a capacitor of 0.12uF. So two in series is 0.06uF. I used a 270ohm and that acts as a low pass RC filter to roll off above 10khz.
If you wire the piezos in parallel, and then add 1/4 the resistance in series with that pair, the response should be the same but 6db louder. From my post, i seem not to have liked that, buf there is plenty of scope to experiment
J
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Post by 4real on Aug 2, 2013 7:01:09 GMT -5
Thats the piezo. They seem to have gone up a couple of $. I angled them just by blocking the mounting screws. . When you are off axis, its better to hear just one so they dont interfere. I didnt really test it though. If you try this, you can just place them on top of the amp to test. My wiring was resistor, piezo, piezo all in series, and that chain wired across the main speaker. Per the article, the resistor would be 100 ohms for this. That would give a full range response with a roll off above audio range. The descrjption suggests that these units each are like a capacitor of 0.12uF. So two in series is 0.06uF. I used a 270ohm and that acts as a low pass RC filter to roll off above 10khz. If you wire the piezos in parallel, and then add 1/4 the resistance in series with that pair, the response should be the same but 6db louder. From my post, i seem not to have liked that, buf there is plenty of scope to experiment J Right oh, in fact if it works out I might have some other things to tweeter and as such things go, it's reasonably cheap. The theory sounds fine and not hard to do and as you rightly say, one can experiement before installing I'm sure. So, this won't change impedences or anything with the amp. What about on a valve amp? You seemed to use 2 different resistors and switches...not sure if I am quite visualizing this set up...I suppose fairly stout switches are more advisable than a mini toggle or the like? Missed out, thankfully, on the eBay mixer thing, it was probably Ok but an older model and ended up selling for $91 and I really wanted the newer versions with compressors anyway... I'm also considering adding a third pickup system, a gooseneck internal microphone, so will need the inputs and EQs to run that lot... |
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Post by JohnH on Aug 2, 2013 7:49:09 GMT -5
This is how I have them wired:  THe amp feels fine, because of the series resistors, it never adds much load on the amp, a negligible change from that of a normal 8 or 16 Ohm speaker. |
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Post by JohnH on Aug 2, 2013 15:38:26 GMT -5
I forgot to mention the switch type. I used standard toggles for robustness. But current isn't much with the series resistor there, and would be fine for any switch. But in fact my big toggles were not so a good choice since theres not enough flowing to keep them well connected - they need a spray now and again. If I did it again, Id use standard sized slide switches, which you often see on the back of amps and cabs doing impedance switching, the contacts are self cleaning, plus they are quite cheap.
'Nuther thing occurs to me, about whether the piezos are series wired as I did, or parallel:
Mine were being connected to a 16Ohm speaker, and I picked the wiring to suit a volume balance that I liked. A 16Ohm speaker gets a voltage swing of 25V if there is 40W power. For an 8 Ohm speaker at 40w, there would only be 18V swing, so my arrangement of tweeters, picking up on that voltage, would be putting out less treble, by 3db. So a parallel wiring of tweeters might be better, which could boost the output by 6db, then adjust with series resistor. Id guess that 50 to 100 ohms might be good for series resistance with a paralleled pair and an 8 ohm cab. 50 would give full range with roll off above 15kHz, 100 would roll off at 8khz.
On my series arrangement, I might raise the output a bit by dropping the 270 ohms to about 150 or 180, for a higher roll-off frequency
J
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Post by 4real on Aug 2, 2013 17:35:13 GMT -5
Ok, thanks for putting the thought into this, I'll definitely want to ahve a go at this and there is a dodgy (scratchy) pot in the amp so might address that too...it is a 60watt solid state combo with single 12, half open back...I'll want switches that will be strong and easy to mount neatly, probably to something like an aluminium plate that I can screw to the side of the cab or something so will check out the options there. So, sounds like the best bet is to get a pair of tweeters and experiement. Perhaps a wire would pot could make something even more adjustable, what do you think? So can you suggest a range of resistors that I should get to do the experiements with then with this scenario...sounds like one could just connect them across teh speaker and try things out till they suit before taking a saw to the amp. I am really hopeful for this mod and I think there may well be more potential in this for a lot of applications as you said in the original thread, especially since you can turn them off and is cheap and easy. There are many sounds one can get out of modelling boxes for instance that are more reminiscent of 'keyboard' sounds...in fact, one wonders if a very clean full range amp is not the best for running modelling effects through than something as midrange and coloured as a 'guitar amp'....and of course, one can always turn them off. Doing a little research, I see they are very popular with bass players and in bass amps...it will be interesting to say the least and I dare say useful. Since I've had my Fender HRD (still needing to be repaired) the Ronland has been a kind of coffee table by the door, so I might as well use it. It was my main amp for years and years and giggedwith it extensively and it never ever has let me down. The fender sounds beautiful (and considering testing the piezo addition to that perhaps for more clean warmth) but there is a lot to be said for reliability I must say. www.ultimate-guitar.com/forum/showthread.php?t=1367224A little reseach on the amp found the above thread, though mine was the earlier mid seventies version lacking a compressor...but largely this is true, they are exceptionally clean and loud (and a bit heavy) the reverb is very deep and lush...the overdrive and master volume thing can be a little harsh as one might expect from a SS amp, but takes effects well and mine has seen decades of use and still great. It has extension speakers, headphone out and lines out and very versitile...If I am taking the guts out as in teh pictures there, switches might be added through the chassis inside the amp perhaps...hmmm...pots look easy to replace so might fix that while I am at it. Better ensure the left tweeter is not obscured by the rolland badge on the grill. And, they are incredibly loud and 'crisp'...  |
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Post by JohnH on Aug 2, 2013 20:07:20 GMT -5
OK, it should be a good candidate. i assume it has an 8 Ohm speaker?
i think the wire wound pot is a good idea, and my bass-player friend has a piezo controlled by one in one of his cabs. What I got stuck on when I thought about it before was chcking the power rating, since whatever is being dissipated in the pot is concentrated into just the part of the track being used. But ive got more data now so Ill see what I can work out. i think it would be ideal if it had a pot, and if something works on paper Ill likley try it myslef too. But if the sums dont add up, Ill suggest some fixed resistors to try.
John
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Post by JohnH on Aug 2, 2013 23:08:32 GMT -5
OK, I did some maths.....
If we say that you want to rate the components to keep inline with a 60W amp power, even though youd never use it, I think its a good starting point.
Assume that power is distributed through the audio spectrum per 'pink noise', ie, equal power per octave, . I read on a forum (so it must be true) that that assumption is appropriate for 'heavy metal'. Not saying your sensitive and thoughtful melodies fit that mold, but its a way to get some numbers!
Then I looked at the tweeter(s) as a capacitor and a resistor in series, across an 8 or 16 ohm speaker which is receiving that input per band. Then I could work out the power dissipation in each band and add them up. I found that with an amp feeding 60W into an 8 ohm speaker, with piezos in parallel and in series with a resistor,the power dissipated in the resistor cant be more than about 1W, and if you do series wiring of piezos its less. If the speaker was 16 Ohm, with parallel piezos, the resistor could get up to about 2W.
All of that means that 5w wire wound resistors are a good choice, given that the next lowest from jaycar are 1W.
Ideally, about a 10W rated 500 ohm wire wound pot could be used, with an extra 50 ohms or so in series, but they arnt available from jaycar.
So, for fixed resistors, 5W wire wound and based on what Jaycar sell for 40c each, Id get a couple each of 22 Ohm, two at 100 Ohm, then one each at 150, 220, 330, 560, 820. they dont seem to do the values below 100 except for the 22, but you can combine in parallel or series.
Slide switch would be my suggestion for the main on/off, and also if you wanted one step of attenuation as I did. Or, you could use a standard rotary switch to give more attenuation choices if you find that to be worthwhile.
cheers
John
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Post by 4real on Aug 3, 2013 0:41:20 GMT -5
Thanks John.... The amp has an 8 ohm speaker if that's any help...little busy but will consider this info... I ahd imagined that one would put a minimum resistor say with the on off switch and a rotary to add more resistance, with a hefty wire wound pot and decent switch...sliders are cool but a toggle is easy to just drill. Looking at that alink to the amp...there looks like there is plenty of room in the tray to perhaps put the switch down inside the cab which is open backed so one could reach in under and adjust as necessary...or an aluminium plate perhaps with the countrols and resistors mounted to the inside of the cab and accesssable from behind. I guess an other option might be a rotary selector perhaps to select various resstors, but I think that is a bit much personally, hard to tell how much this control would effect things...is it a subtle thing? I just need to work out a parts list, do an order and likely an afternoon job...if I found an afternoon... OK, I did some maths..... If we say that you want to rate the components to keep inline with a 60W amp power, even though youd never use it, I think its a good starting point. Assume that power is distributed through the audio spectrum per 'pink noise', ie, equal power per octave, . I read on a forum (so it must be true) that that assumption is appropriate for 'heavy metal'. Not saying your sensitive and thoughtful melodies fit that mold, but its a way to get some numbers! Then I looked at the tweeter(s) as a capacitor and a resistor in series, across an 8 or 16 ohm speaker which is receiving that input per band. Then I could work out the power dissipation in each band and add them up. I found that with an amp feeding 60W into an 8 ohm speaker, with piezos in parallel and in series with a resistor,the power dissipated in the resistor cant be more than about 1W, and if you do series wiring of piezos its less. If the speaker was 16 Ohm, with parallel piezos, the resistor could get up to about 2W. All of that means that 5w wire wound resistors are a good choice, given that the next lowest from jaycar are 1W. Ideally, about a 10W rated 500 ohm wire wound pot could be used, with an extra 50 ohms or so in series, but they arnt available from jaycar. So, for fixed resistors, 5W wire wound and based on what Jaycar sell for 40c each, Id get a couple each of 22 Ohm, two at 100 Ohm, then one each at 150, 220, 330, 560, 820. they dont seem to do the values below 100 except for the 22, but you can combine in parallel or series. Slide switch would be my suggestion for the main on/off, and also if you wanted one step of attenuation as I did. Or, you could use a standard rotary switch to give more attenuation choices if you find that to be worthwhile. cheers John |
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Post by sumgai on Aug 3, 2013 12:34:45 GMT -5
I'm feeling spunky this morning, so...... John, the problems here are: a) A piezo tweeter is considered a capacitive device. Connected in series with a resistor, you have on your hands an RC network, which you'll recall from your standard guitar controls, is a high-pass circuit. With a resistor in series, you don't actually change any frequency cut-off, lower or higher - you simply differentiate the amount of energy going to the device in question. b) Power dissipation is a concern, and in high-fidelity amps, it becomes a large concern. Even though we're not doing a 20-20KHz amp here, there's no reason to stint on a proper crossover. Which you've done - the 22Ω 5w resistor will work to dampen the reflected energy that would ordinarily go back to the amp, and possibly cause it to become unstable. That instability is what gives piezos a bad name - it works to color the sound not only in the upper end, but a good part of the way down into the mid-range frequencies too. By the same token, inserting too much resistance in series not only dampens the reflected energy going back to the amp, it also starts to work against the piezo's capabilities. One needs to keep the amp's need in mind when using cross-overs, it's quite true that no two amps will react in the exact same way (nor will they act/react in the expected way, IME) to what's coming back in via that "back-EMF" mechanism. Amplifier stability is important, even to guitarists. Output transformers found in tube circuitry go a long way towards "tolerance" of abusive output setups, but solid-state gear needs more "love", if you will. c) A good attenuation control will be part and parcel of the cross-over network, and not just an additional resistor in series with the piezos. That does entail some more parts, and a commensurate higher cash outlay, but then again, what price quality, eh? Piezo tweeters come in all levels of quality. But more importantly, sometimes you don't want the ones that can reach upwards of 45KHz - those may be too harsh for the guitarist's needs! Instead, use a tweeter that claimes only 25-27KHz as the top end. Even if it's "cheap" (inexpensive), it still might sound better overall. Obviously a lower-claimed top end will also be a candidate in this application, but remember, all electromechanical tranducers will color the final output (the sound). At the price levels of most of these things, one can seriously afford to shop for several different units, and experiment to their heart's content. For review, might I suggest a quick glance at this page: www.frugal-phile.com/piezo-XO.htmlAs we used to say in the business, that's only a good First Approximation. Google/Bing/etc will bring deeper insights into how this all comes together. HTH sumgai |
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Post by JohnH on Aug 3, 2013 19:31:32 GMT -5
Hi Sumgai An interesting and useful link. There is always room for experimenting. Without the cross-over, the piezos are presumably twitching somewhat in response to voltages due to low frequencies, and this could cause an issue if the power was high enough. But I contend that there is nothing wrong with what I am describing, on account of the fact that I know that it works fine, based on analysis, experimentation with different values, having built the system, tested it, measured the response, and used it frequently, including at high volume at a number of gigs, with both ss and tube amps. One might be tempted to quote George Bernard Shaw: www.brainyquote.com/quotes/quotes/g/georgebern163003.htmlHowever I won’t, since I see there is merit in finding out whether any improvement can be made by keeping low frequency signals off the piezo, while still having a system that can be added to a guitar amp without changing the load, or causing an instability, and without excessive losses. I believe the series resistor, as recommended in nearly all references, is a better way than just the parallel resistor proposed in your link, to keep the system stable. This is because with just a parallel resistor and series cap, it still directly connects capacitance to the speaker inductance, risking a resonant circuit. I would be very hesitant to connect that to one of my amps, while with an adequate series resistor as I do, there is no issue for the amp. |
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Post by 4real on Aug 3, 2013 20:51:16 GMT -5
Thanks for the great replies and considerations here...all good food for thought. Discussions here as they seem to be very popular with bass players... www.talkbass.com/forum/f15/do-piezo-horns-require-crossover-376190/This thread hre seems informative and shows some ideas for adjustable rehostats and discussions of teh capacitor. Obviously, I don't want to hurt the amp or speaker, nor what a harsh brittle sound or distorion but the extent to which people including joun have done this without any damage and sounding good, indicates that this is the right track and sure, a cap could be added at minimal cost. I assume it would need to be something that could stand the power so guidance there might be useful...  The link to the tweeters in question... www.jaycar.com.au/productView.asp?ID=CT1930This unit is similar to the KSN1005. Does not require a crossover and is perfect for use for general PA applications where long throw is required. These piezo horn tweeters have built-in protection to allow them to handle 400W RMS. At high power levels, a PTC opens, allowing the tweeter to continue to play at a compressed power level. Using my amps 6 band EQ, I maxed out all bands and reduced the 1.5kHz a notch and the 2.5kHz to the middle, the higher 5kHz to max. It is a smoother sound bat lacks that high end 'zing' that acoustics produce and wanting to get out of the amp with this mod. However, this mid 'scoup' does tend to indicate a smoothness of that midrange is desirable and perhaps that might influence the kinds of calculations and the use of the cap to keep lower end out of the tweeter...an adjustable variation might also be a good thing as that would allow some 'tweeking' of thing to suit the amp and the sound desired from it and at least seems 'possible'... These things look very similar or may well be these devices which has some interesting 'reviews'... www.parts-express.com/pe/showdetl.cfm?partnumber=270-011From John's link at www.pulsardevelopments.com/products/detail/piezoan.htmlThere is discussion of using an additional cap and this might be indicated by my use of the eq on the amp to dampen those lower highs, to be advantageous...but you guys would be far more understanding of these things and the maths! I take it though, that the cap would be a small and inexpensive part and if a value and type were recomended worth the $1 to experiement with it...I suspect it might be worthwhile and help protect against oscilations and harshness...maybe |
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Post by sumgai on Aug 3, 2013 22:49:50 GMT -5
John, What works is what works, like the nice man said. However, without knowing the underlying details, one can be easily tempted to say "hey, it works without blowing up, so it must be OK, right?" Well, yes and no. Just because an amp "works" and "sounds good" doesn't mean that it's percolating along as well as the designer/builder intended. Without throwing it under a 'scope and testing it per standard procedures, you don't really know if it's breaking up -just under the threshold of audibility- or not. While it's not common in pro-audio, over the years I have encountered amps that did strange things, and when I put them under the 'scope, I would see all manner of distortion that literally could not be heard, but it was present, nonetheless. Was that distortion damaging in some way to the amp under test? Who knows. All I can say is that when it left my bench, it worked as advertised, without potential life-shortening problems. But Mr. Shaw is correct in the larger sense of the word - just because it's not technically correct, that doesn't mean it should/must be abandoned. In the final analysis, if it works for you (the owner) then who's to say that it can't/shouldn't be done, eh? After all, it's your rig, and if you're willing to live with any compromises, seen or unseen, then I'm not gonna get all lathered up about it, to be sure. HTH I should add..... Pete, nice discussion! I like the way you think, and the way you and John come at things from different angles, then hash it out with lots of "oh hey, what about this idea?" give and take. My money is on you coming up with a trail-blazer of an amp mod that more than a few souls will want to copy. If you can, try to take sound samples before and after, using the same guitar, strings, cable, etc. Since this is an audio experience, you'll need to mic the speaker(s), so take notes on the placement of that, and if you run it through any kind of pre-amp or eq, then jot down those settings too, please. Anything to compare apples with other apples, instead of oranges. Good luck! sumgai |
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Post by JohnH on Aug 4, 2013 1:04:44 GMT -5
all good then. Here is a design candidate for using these piezos with some crossover to roll off lower frequencies:  The piezos are represented as a capacitance, of 240nF which is two of them in parallel. R1 is a series resistance, so Id be happy to connect it to amps. The impedance of this whole contraption would never be below this value and at 50 Ohms, its several times the speaker load and there is no direct connection between inductors and capacitors. R2, together with C1 provide the low end roll off, so there is a lot less voltage due to low frequencies with this. But the wanted frequencies are kept highish. There is some high end roll off, which I think is a good thing. The max response is about -3.5db down from what it would be without R2 and C1. But the use of the piezos in parallel is inherently 6db louder than in series as I have them. But with an 8Ohm system instead of 16 Ohm, the signal voltage will generate about 3db less output. All of that implies its all within 1/2 db of being a wash. Cap C1 needs to be non polarised, ie not an electrolytic.I'm thinking two 470nF in parallel will do this nicely - no other special requirements for these needed. The plot shows the db response, with the red line as drawn, and smaller caps tested on the other traces. Untested of course, but low risk and cost, so worth adding to the lab-test program. John |
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(no reverb though)
