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Post by mr_sooty on Oct 9, 2008 17:10:15 GMT -5
I have a biggish pedalboard, with 11 or so pedals. It's all wired up with el-cheapo proel and warwick patch cables, the prepacked multicoloured ones you buy cheaply at most music stores. I have cut one of these cables and found the wire inside to be mutil-stranded copper wire, which looks pretty reasonable to me.
I get abit of hiss from my board. Not sure why this is exactly. I'm powering everything with a 1700ma capacity switchmode adaptor (Godlyke PA9) and my pedals add up to about 900ma draw. I think my DD20 Digital Delay is causing the most hiss. It draws 200ma by the way. But there's still a small amount of hiss if I take that one out of the chain.
Everybody tells me I should get these George L's solderless cables. I really don't see the point. They're very expensive for a start, and I reckon solderless is asking for trouble. I have heard of these fail. In over 15 years using the cheap proels, I've never had one fail. I also notice almost no tone difference between my signal going through my pedal board (all bypassed and straight into my signal going straight amp.
But could better cables help the hiss? Or do I need a better power supply?
I don't really see how it could make any difference. The way I see it, when my signal is going through a run of pedals, some buffered, some True Bypassed, the signal is travelling through all sorts of little bits of hook up wire, circuit board printing etc. Surely the copper threaded Proel Cables are at least better than the little bits of hook up wire connecting my inputs to my outputs in my true bypass pedals.
So what difference would getting George L's make?
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Post by JohnH on Oct 10, 2008 14:35:00 GMT -5
Hi sooty - My guess would be to agree with you, that the cheap patch cables are fine, so long as they are in OK condition and giving you a reliable connection. I dont think the patch cables would cause hiss. Bad cable with poor screening can cause hum, but even basic ones deal with this OK. Unlike the one that came with my sons Behringer starter pack.
I also doubt that the hiss comes from the power supply, problems there would be more likely to be mains hum and buzz, or distortion (and smoke and flames?) if you you really overload it.
The hiss would be a combination of the gain you are using on the amp, combined with all the pedals which are either switched on on not true bypass so their buffers are always working. My ideal setup would be one buffered pedal at the front, probably a tuner, then all true bypass after that.
If its too bad, can you make a passive looper switch to bypass a group of non-true bypass pedals.
BTW, thanks for the tip recently on the 3PDT stomp-box footswitches from Jaycar. They have hit our local store so I bought some, and a good price too.
John
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Post by mr_sooty on Oct 10, 2008 16:09:56 GMT -5
Cool! Glad to have actually helped someone on this site for once! Usually it's just me leeching advice off you genius's.
I thought about getting a looper, don't really have room for one, but I could make room. I don't really have a problem with 'tap dancing', just hiss.
As far as bypass goes, my chain starts with a wah. I dunno what sort of bypass this is. I did a true bypass mod on it, and didn't like the 'pop', so I reconnected the wire that goes from the curcuit to the input jack. It still runs a bypassed signal without power, so I guess this is what you'd call a 'hard bypass' (?).
Next I have buffer, buffer, TBP, Hard Bypass (I think), TBP, Buffer, TBP, TBP, TBP, TBP.
So out of 11 units in my chain, there's only three buffers that I know of. Would that be enough to cause problems with hiss?
Fact is, the hiss is only really an issue at all when certain pedals are on together. For example, my clean boost pedal (Durham Sex Drive) combined with my medium gain Blues Breaker Clone is a big hiss combo. That Blues breaker clone is a homebrew too, the first (and only so far) pedal I ever assembled. It seems to be the hissiest of the lot. I wonder if this is to do with my assembly? Possibly some of the hookup wires could have been trimmed a little shorter. Put the Homebrew on with another gain pedal and the clean boost and it becomes almost unuseable.
I've read people claim that a Voodoo Labs Pedal Power 2 cleaned up hiss, but I wonder if there's any truth to this. I've noticed my homebrew pedal doesn't seem to make noise with a battery, but then, when I test it with a battery it's usually by itself. It this situation it's fine.
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Post by mr_sooty on Oct 10, 2008 18:04:44 GMT -5
OK, so I did a little test with the two gain pedals and the boost pedal on their own running off batteries. They certainly hiss when on and combined, but not when bypassed. My pedal board does add a bit of hiss to my amp even when everything's bypassed, but it's not serious. I guess it's just an accumulation thing. I think I'll just live with it.
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Post by ashcatlt on Oct 10, 2008 23:05:52 GMT -5
It's also a gain thing. You're turning up the noise along with the rest of the signal. Especially if you've got any amount of compression (including OD and distortion) where you're smashing the louder parts down closer to the quieter parts (where the noise lives) and then cranking the whole thing back up. If you find a pedal that actually is noisier with a wallwart compared to the battery...well we've been down that road before. Remember? |
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Post by mr_sooty on Oct 11, 2008 0:01:56 GMT -5
Yes, yes we have. The purpose of this thread is really to find out if you guys with more practical knowledge of electronics and signal transfer think that buying 'better' patch cables will have any positive effect on the signal, or whether it's kind of just a lot of hype. Let's put my hiss issues aside for the time being.
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Post by ChrisK on Oct 11, 2008 10:00:10 GMT -5
Gain is.
It sounds like your Blues breaker clone pedal is too clean. Maybe some internal high frequency filtering would help. It's going to be a trade-off between frequency response (signals of interest) and, uh, frequency response (signals of noise).
This could be mitigated with an EQ downstream, they tend to have steep slopes, but then there's that trade-off again.
This can also be controlled with a noise gate triggered by a certain level of desired signal. But then it becomes a choice of levels of interest vs noise.
Then again, depending on the input noise/hiss to the signal chain and its fidelity, it could be guitar detected noise that is unobtrusive until gain is applied. If so, we know where to look for this, eh?
The short inter-effect cables should have excellent shielding, and low capacitance if bypass-chained into an effectively longer cable.
While I don't put much stock into the ground loop "issue" within a passive electric guitar (most impedances are high so most small ground impedance are meaningless), once you get to an active signal chain, ground loops, inadequate enclosure shielding, and bused power supply all come into reality.
While the signal and ground chain are sequential thru an effect chain, once a common bused supply is added, the ground chain is effectively parallel grounded to the bused supply ground with the last effect in the signal chain effectively feeding the star ground information into the amp in ground (?grand?) concert with the signal return from said last effect. Effectively, every path consisting of the signal ground to the next effect in the chain is bounded with a return path from each (the bused supply ground) forming a small local ground loop. If you have 6 effects, you have 5 local ground loops. It is unlikely that most effects have any consideration of separation of signal ground from supply ground, but if they do, this will defeat it. I don't know if the separate supply outputs from the bused power supply are isolated, but referring to your previous questions about power cable chains, I don't think so. Holy ground modulation Batman.
I guess that the electrical placement of effects in the power chain may have more value than the usual mechanical placement for convenience.
Many effects suffer from inadequate enclosure shielding of the unshielded untwisted internal conductors. If these add up to 4 inches total, that's 1/3 of a short interconnect cable with bad shielding.
I do believe that the internal guitar shielding SHOULD NOT BE USED as the signal ground. All signal returns/grounds should have a common star reference point, which, in the interests of wiring ease should be the ground terminal of the master volume pot (if you got more than one, choose one with the best effect such as the bridge).
I often say signal return in lieu of ground for a pickup coil since, with the exception of single conductor with shield or anywhere the shield is used (incorrectly) for a signal conductor, "ground" is an arbitrary designation for phasing correlation.
Passive high cut tone controls, as shunting impedances across pickups do not require the best of grounding to the star point, but do indeed require a good connection. Volume controls and pickup signal returns require the best connection to the star point, as does the output jack (the input jack is on the next thing in the chain).
Isolation capacitors change this around a little, but this "star" point should be where (and only where) the shield and signal ground meet, to begin their bound journey down the inadequate highway known as the single conductor with shield guitar cable.
Now, let me be honest here. I'm discussing this as an electrical engineer. As a pseudo-musician, I have little use for separate effects in a chain due to the aforementioned "effects". I always use effect panels such as the Boss ME-50 and other modelers since I can't hear the difference with my failing hearing (yes, we all get old).
This is not much direct direction, but primarily a discussion of my observations.
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Post by mr_sooty on Oct 11, 2008 20:07:45 GMT -5
It sounds like your Blues breaker clone pedal is too clean. Maybe some internal high frequency filtering would help. It's going to be a trade-off between frequency response (signals of interest) and, uh, frequency response (signals of noise). I am interested in this. The bluesbreaker clone can afford to lose some tops, as it's a very bright pedal. I would be prepared to try some high frequency filtering on it if you can point me in the right direction. Actually I sort of had a go at it based on the Wah power filter, but the truth is, I had no idea where to put it. Perhaps you can tell me? Here's a diagram: www.generalguitargadgets.com/pdf/ggg_mbb_lo.pdf |
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Post by ChrisK on Oct 13, 2008 16:15:30 GMT -5
No time (or inclination) to decipher a PCB layout, schematic please.
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Post by mr_sooty on Oct 13, 2008 20:00:35 GMT -5
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Post by ChrisK on Oct 17, 2008 23:29:09 GMT -5
C4 could be increased to add additional high frequency roll-off. However, this stage is before the clipping stage (which introduces harmonics) and may not have great effect.
C6, R8 and C7, R7 seems kind of silly, a 10K and 0.1uF in lieu of all four would work exactly the same.
C8 could be increased to decrease the corner frequency of the output tone control. C9 could be increased to add more high frequency roll-off.
FYI
Essentially, increasing the capacitance in the feedback path of an OPAMP will effect an increase in high frequency roll-off (C4 for example).
Decreasing the capacitance in the input path of an OPAMP will effect an increase in low frequency roll-off (C7 for example).
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Post by mr_sooty on Oct 18, 2008 3:03:08 GMT -5
C8 could be increased to decrease the corner frequency of the output tone control. C9 could be increased to add more high frequency roll-off. Cool, thanks. How much increase is needed to make a difference, and how much is too much? |
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Post by ChrisK on Oct 18, 2008 13:46:33 GMT -5
I don't know. What does "difference" mean? Doubling a capacitor value will halve a frequency point. If the value is 47pF, try 100pF (0.1nF). If the value is 0.01uF, try 0.022uF (22nF - a common tone cap in guitars). (Try C8 and/or C9 first.) I can't hear that far, you'll have to season to taste.  |
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Post by mr_sooty on Oct 19, 2008 21:38:06 GMT -5
Pedal all sorted, thanks to ChrisK's suggestions and a bit of experimentation.
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Post by mr_sooty on Oct 20, 2008 18:32:10 GMT -5
Just to clarify, here's what I did:
I tried 0.022, first in C9, then in C8. sounded pretty good in C8 but was a a little bit too much in C9. So I backed the C9 down to 0.015, and the C8 to 0.018. This has given me a pretty good result. Has got rid enough of the noise to bring in line with my other gain pedal, and it's got rid of some of the 'icepickiness', without muddying it up too much. I can roll the tops back in with the tone knob too, so it's all about right. Plus, it's almost like my own design (with Chirs's help!), because I tried a couple of values and came up with what I liked.
Just as well I'm happy too, because those little solder pads were starting to come off with all the resoldering. Fortunately I know how to work around that, thanks to this forum.
I think this has helped way more than 'better patch cables' would have. I'm just always getting guitarists telling me I need to upgrade my patch cables, and I really don't see the need. Signal leaves one pedal, goes to the other one.
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