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Post by sumgai on Aug 28, 2019 11:49:33 GMT -5
trag,
Show me more images of that cap, from different angles... please.
sumgai
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Post by thetragichero on Aug 28, 2019 20:00:50 GMT -5
so we have a wooden shim, some hot glue/other adhesive, and some bus wire holding it to the board i know it's not usual to replace Mylar caps but I've got a box film cap coming in my electro cap order
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Post by sumgai on Aug 29, 2019 0:07:55 GMT -5
I think that someone was afraid of a future 'repeat' failure, and took steps to avoid any such. Meaning, the original cap (this or another one) came unsoldered, or otherwise unsecured, and caused him/her no small amount of grief. Not what I would've done, but then again, any port in a storm, eh? Unless you see burn/scorch marks somewhere near by.....
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Post by thetragichero on Sept 8, 2019 23:29:54 GMT -5
edit 1/21/2021: i moved a number of the preceeding posts to their own threadand i redrew the schematic from the scribbled mess in my notebook slightly less messy
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Post by sumgai on Sept 9, 2019 11:13:23 GMT -5
traj,
If that schematic just above is what you built from the Hammond unit, then you don't have a Baxandall tone circuit, only a "standard" setup.
Peter Baxandall made a difference when he 'went active' by putting the tone stack in the feedback loop of an amplifier stage. IOW, a Baxandall circuit requires an amplifier stage (making it 'active'), and a standard setup does not. What we normally see in guitar/bass amps is one or more pre-amp stages that 'recover' the losses of a standard passive tone stack. That's what's going on in your rig. Oh, and your first stage should have pins 6 and 1 swapped. Unless you have the world's first internally modified 12AX7....
HTH
sumgai
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Post by thetragichero on Sept 9, 2019 11:36:22 GMT -5
labeling error shhhh ;-) both triodes paralleled, so in that socket pins 1 and 6 are interchangeable :-P i believe you are correct about the tone stack. technically it's called a james tone stack when it's passive. it's definitely my favorite though
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Post by reTrEaD on Sept 9, 2019 11:44:57 GMT -5
If that schematic just above is what you built from the Hammond unit, then you don't have a Baxandall tone circuit, only a "standard" setup. The tone network in that schematic is definitely Baxandall, even though it's the passive version. Ampeg used this on most of their amps and I rather like it. The 'standard' FVM (Fender/Marshall/Vox) is a different animal entirely. The two (or three) pots in those are stacked in a series arrangement and it's pretty good at scooping mids and pretty much nothing else.
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Post by thetragichero on Sept 9, 2019 12:04:00 GMT -5
older orange graphic amps used the same style. I'm a mids guy so the standard vox TB control (from the ac15 schematics i copied most of the preamp from) did not look cool with its inherent mid scoop. fiddled with values in Duncan's wonderful tone stack calculator until i found something that was suitably flexible (bass or treble 'boost' or mid 'boost' with treble and bass turned down) I've dipped my foot in the pool of circuit analysis before i even think about ordering parts. I'll eventually get to spice modeling
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Post by reTrEaD on Sept 9, 2019 15:24:39 GMT -5
fiddled with values in Duncan's wonderful tone stack calculator until i found something that was suitably flexible (bass or treble 'boost' or mid 'boost' with treble and bass turned down) For those reading who might wonder about that: www.duncanamps.com/tsc/I don't have that on the computer I'm currently using but I made extensive use of it in the past. I rate it right up there with some of the best free stuff on the interwebz.
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Post by sumgai on Sept 10, 2019 1:21:47 GMT -5
If that schematic just above is what you built from the Hammond unit, then you don't have a Baxandall tone circuit, only a "standard" setup. The tone network in that schematic is definitely Baxandall, even though it's the passive version. Ampeg used this on most of their amps and I rather like it. Below is a link to the original release of Baxandall's design. Sadly, I can't print it here, as it's in PDF format, and it's about 7 pages long, with diagrams.
Baxandall Circuit
Note the title of the article, and the several subsequent mentions of "negative feedback" - it's necessary in order to incorporate a Baxandall tone stack into an amp. I could give many other source links upholding this train of thought, but do I really need to do so? Certainly the original thoughts of the man for whom the design is named should be sufficient, no?
But let's go ahead and take this one step further, which should put paid to the account. In a Baxandall circuit, you can have both cut and boost. (See the clearly laid-out schematic on Pg. 5) This is an inherent property of using an amplifier stage within the tone control signal path. Outside of that "intimate loop", you can't have boost, period. You can amplify the overall signal to "recover" from your losses within the tone stack (where everything is a cut), but that's not directly boosting the desired frequency band(s).
Other points that denote a Baxandall circuit: - The original circuit used just two controls for Treble and Bass. In those days, controlling the Mids was unheard of. - The amplifying device within the circuit is designed to exhibit an overall gain of unity (meaning, no amplification and no losses - overall). - Regardless of the number of capacitors that one counts, the circuit is not a Baxandall if it's not incorporated into a feedback loop. This obviates the Ampeg models mentioned above. (I checked several, but certainly not all of 'em. Specifically, the GVT series has been quoted several times around the net as using a Baxandall layout. Nope.) - There were no passive or otherwise modified versions until some time after P.B. himself passed away, in 1966. But even then, if you read the notes of groups like The Audio Engineers Society, you'll see people decrying the "lay persons out there trying to dilute (or worse, misappropriate) Peter's work." Even right on the Wikipedia page there are links that go to gawd-awfully bad information. Sad, that.
But I say again, and this might become my mantra.... if it works, just use it! Things like a couple of amp-nerds on some Nutzy website that have different opinions shouldn't hold you back from having fun (and hey, maybe even make some money at the same time!).
HTH
sumgai
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Post by reTrEaD on Sept 10, 2019 9:42:35 GMT -5
Below is a link to the original release of Baxandall's design. Sadly, I can't print it here, as it's in PDF format, and it's about 7 pages long, with diagrams.
Baxandall Circuit
Note the title of the article, and the several subsequent mentions of "negative feedback" - it's necessary in order to incorporate a Baxandall tone stack into an amp. I could give many other source links upholding this train of thought, but do I really need to do so? Certainly the original thoughts of the man for whom the design is named should be sufficient, no? This line of reasoning is wholly unconvincing. It suggests that because Peter J Baxandall wrote an article entitled Negative-Feedback Tone Control, any configuration which bears his name must necessarily employ negative feedback. I reject this premise. Later I will make a concession, but it's not based what you've written so far. But let's go ahead and take this one step further, which should put paid to the account. In a Baxandall circuit, you can have both cut and boost. (See the clearly laid-out schematic on Pg. 5) This is an inherent property of using an amplifier stage within the tone control signal path. Outside of that "intimate loop", you can't have boost, period. You can amplify the overall signal to "recover" from your losses within the tone stack (where everything is a cut), but that's not directly boosting the desired frequency band(s). There's some parochial reasoning being applied there. While it's true that in the FMV tonestack everything IS a cut, that is not true of other passive tone networks. There are insertion losses in a proper tone network if it's strictly passive, but the mid-point of the treble and bass controls is where the overall frequency response curve is 'flat'. Turning either knob clockwise will result in a boost (or using the period correct terminology 'lift') relative to the flat setting. If one chooses to split hairs they might point to the fact that even when the treble control is at maximum, the output in the treble region of the response curve is still less than the signal at the input. But that totally misses the point. Other points that denote a Baxandall circuit: - The original circuit used just two controls for Treble and Bass. In those days, controlling the Mids was unheard of. - The amplifying device within the circuit is designed to exhibit an overall gain of unity (meaning, no amplification and no losses - overall). - Regardless of the number of capacitors that one counts, the circuit is not a Baxandall if it's not incorporated into a feedback loop. This obviates the Ampeg models mentioned above. (I checked several, but certainly not all of 'em. Specifically, the GVT series has been quoted several times around the net as using a Baxandall layout. Nope.) - There were no passive or otherwise modified versions until some time after P.B. himself passed away, in 1966.
I'm pretty sure he died in 1995. It seems to me, you're killing off Peter rather early. What did he ever do, to you to deserve such a fate?But while we're still in 1966, lets stop by the store and pickup an Ampeg B-15. Introduced in 1960, it indeed used the misnamed 'passive Baxandall' circuit. Wait ... what? Misnamed? Yep. This is where I'm willing to make a concession. Not based on any of the arguments that have been presented, but because of some research I just did. www.thermionic.info/james/James_SimpleToneControl.pdfPublished in Wireless World, February 1949. That predates Baxandall's article by well over three years. So it appears the misnamed 'passive Baxandall' wasn't a 'dilution' of Peter's work but should properly attributed to E J James.
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Post by thetragichero on Sept 10, 2019 11:44:52 GMT -5
letter to the editor at the end states the James tone stack might have actually originated in Belgium in 1939... i no longer feel so bad about about mixing and matching modules from famous effects/anymore. seems like this is how it's always been! like this: i took a break last night to get this fuzz off the breadboard it's been on for months, adding stuff before it. it's the input booster from a big muff (even used a metal can 2n2222 i had replaced with a modern i equivalent in a preamp that was giving me grief), feeding my closest approximation of the orange graphic series tone stack (used parts i had on hand instead of the ones i forgot to stock up on.... hey look a James tone stack!) feeding a genius fuzz/gain stage i stole from here: he mentioned this is a great spot for all those leaky crappy nte germaniums and i must concur. used a dual op amp so the other half is a voltage follower. way overkill but i didn't have the single version of this series i thought the tone control would be interesting before the fuzz because of i want splatty i can crank the bass, if i want cut i can goose the treble. if i just want some delicious midrange fuzz goodness i can back off the bass and treble and get a nice broad mid hump right in the area of the fundamental frequencies of the geetar
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Post by reTrEaD on Sept 10, 2019 12:18:47 GMT -5
letter to the editor at the end states the James tone stack might have actually originated in Belgium in 1939... i no longer feel so bad about about mixing and matching modules from famous effects/anymore. seems like this is how it's always been! Good catch. Perhaps Michael Volkoff should get a tip of the cap here. We should probably reserve the term 'tone stack' or 'tonestack' for those circuits which basically resemble the FMV configuration where the elements are 'stacked', essentially in a series path from input to ground. Unlikely to happen though.
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Post by sumgai on Sept 10, 2019 13:43:03 GMT -5
reTrEaD,
Yes, he died in '95 - I was in grievious error on that one. I was researching several other topics/people at the same time, and wasn't keeping close enough track of who did what, and when. Apologies to the Baxandall family and estate.
I'm familiar with James, and I don't reject his work, but I say again, the cognoscenti both of that day and now have fairly made an institution out of the Baxandall design and the surrounding claims. I can't say that I think P.B. "stole" anything from E.J. James, but I wasn't there, so I can't be sure, either way.
As to rejecting the idea that negative feedback is not necessary in order to have a Baxandall circuit, I'd have to say that you and I are definitely on different wavelengths here. Sorry 'bout that, but there we are, and most likely, there we'll continue to be. But further to that, I readily admit that I was not aware of M. Volkoff's work a priori. I need to do some more research on that one.
As to having a passive circuit exhibit gain, there I will stand on both tradition and long-ago set standards. You simply cannot have coming out more than what you put in... without doing some kind of adaptaive conversion of power from another source.
Let me explain it like this: a conversion of this kind means that we are taking power from a large reserve source (ex. the wall socket, 110vAC mains), and adapting it for our uses, i.e. we want to hear a very low level signal (our guitar pickup(s)). The very foundation of all this is that we use the low-level signal to modulate the high-level reserve source power supply. For our purposes here in the realm of audio production/reproduction, that form of modulation is called amplification. And yes, that explanation is way too simple, but it nicely encapsulates the action that goes on inside the amp.
Now, I hear once in awhile, that we can get more out than we put in due to resonance. I almost shouldn't even dignify that argument with a response, but it cuts close to my heart - I ranted over this very topic, now 12 years ago, with Channelman. He eventually had enough of he called my crap, and bowed out of The NutzHouse. That was an overall loss, I'm sorry to have to admit.
But the bottom line is this: It is set in stone, once and for all, that 0dB is the level of maximum signal through a passive circuit. Let me repeat that: 0dB is the level of maximum signal through a passive circuit. There is no "except for resonance", and in fact, it means, "at resonance, where found". That's a period, there are no other ways to discuss it.
So we fast-forward to the age of the Internet, where all bad things proliferate at approximately the speed of light squared, and anything good is shouted down as antidiluvian. Almost makes me wanna cry. But the net effect is, someone, in their greatest possible temerity, ignored that tenet and set 0dB as being an arbitrary starting point for measuring a signal's progress through a passive cirucit, and when they unexpectedly found the peak at resonance, they shouted "Eureka - I found gain without outside power!!". BAH! Humbug!! That's willful ignorance speaking, not erudition. What's most exacerbating is that such has now become standard practice in SPICE software. IMO, that's a criminal act because you never have resonance at Zero Hz. So why was 0dB arbitrarily assigned to 0Hz, and allowed to remain there throughout the plot? Bleeping good question, if you ask me.
Nowadays, I'm trying to keep my tone down to a dull roar, but my need to keep things on a foundation that doesn't crumble is still just as keen. If anyone reading this takes away just one thing, it should be that 0dB is the maximum that a passive circuit can hope for, there is no magic boost, whether due to resonance or Jack's Magic Beans, or whatever else is the BS de jour. To make a person really think about this, I'd have to ask: if this were true, why don't we just build circuits that don't need any outside source of power?
Parochial? Sure, but that doesn't make me wrong, only pig-headed.
All of which brings us around to the starting point: Ampeg used a passive tone control setup that did not incorporate a feedback loop, but did incorporate circuitry inspired by E.J. James, who can be shown to be a predecessor to Baxandall. And remember, the point of Baxandall's design wasn't just that he took an earlier design and put it inside of a feedback loop, it was what audio engineers of the day described as a "very novel approach, something that hadn't ever been done before". Perhaps that's why his name is attached so closely to the design, and not any of his predecessors. Who knows?
That's all for now, I'm done.
sumgai
(Some points may have been missed in the making of this post. Hopefully they won't feel bad about being ignored.)
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Post by reTrEaD on Sept 10, 2019 15:50:26 GMT -5
I can't say that I think P.B. "stole" anything from E.J. James, but I wasn't there, so I can't be sure, either way. All you need to do is to take a look at Figure 5 from the link you provided from Baxandall and compare that to the James (or should we say Volkoff?) circuit. Move the right hand node of R 2 from the plate circuit and connect it to ground instead. Bam! You have the same configuration used for the bass in the James circuit. Input at one end, plate or ground at the other, with a pot and pairs of equal value resistors and equal value caps. Likewise the summing resistor between the treble and bass. There is a notable difference in the treble portion. This requires a tapped pot. But I'm almost certain I've seen later versions of the active circuit with the same configuration on the treble side without a tapped pot. Were the bass section and summing resistor 'stolen'? I tend to think that might be a bit narrow-minded. Sort of like saying because you have a circuit with a resistor in series and a cap in parallel with the output, you stole the high-cut filter. But the commonality between elements and configurations between the Baxandall and James (save for the negative feedback) is all too striking to ignore. As to having a passive circuit exhibit gain, there I will stand on both tradition and long-ago set standards. You simply cannot have coming out more than what you put in... without doing some kind of adaptaive conversion of power from another source. I did not say nor even imply that the signal at the output of the passive circuit is greater than or even equal to the input anywhere on the frequency response curve. To the contrary ... I'll try this one more time before I begin throwing things at you. The boost (or 'lift as James called it) is NOT in relation to the signal at the input. It's in relation to the overall insertion loss. Thus if we have a 20dB loss across all frequencies when the controls are at their midpoint, and a 5dB loss in the treble region when the treble control is rotated to it's clockwise extreme (and the bass and midrange still exhibit the original 20dB loss), then we have a net lift of 15dB in the treble ... relative to the bass and midrange. And remember, the point of Baxandall's design wasn't just that he took an earlier design and put it inside of a feedback loop, it was what audio engineers of the day described as a "very novel approach, something that hadn't ever been done before". Perhaps that's why his name is attached so closely to the design, and not any of his predecessors. Who knows? Acksually, it pretty much was putting an earlier design inside a feedback loop, save for the tapped pots and associated circuit change in the treble network. Granted, the use of negative feedback made for much better 'tracking' of changes in the response curve as the pots are rotated from their midpoint. So it was a marked improvement.
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Post by blademaster2 on Sept 10, 2019 16:29:27 GMT -5
I am late to this party, but I never saw anything in my engineering courses that said a passive circuit *must* have its maximum signal amplitude defined as 0dB. Usually, the 0dB level is defined for convenience as a reference level, and that anything above or below it is either amplified or attenuated relative to that reference (after all, dB is only an expression of a ratio). As such it was always perfectly acceptable to define a passive circuit with 0dB from DC up to frequencies of interest where filters and other frequency-related effects start to have an impact. Insertion loss may or may not be present, and it did not not matter either way. Also, a peak resonance amplitude has never, in my history, been defined to be 0dB as a mandatory thing (perhaps my history starts at a very different timeline than that to which Sumgai refers). A transformer is an example of a passive circuit that certainly can amplify the output voltage level above the input voltage. The key here, about "not getting something for nothing", is *power* and not voltage. The transformer provides lower current when it is providing higher voltage. No passive circuit can amplify power, of course. An acoustic guitar is said to "amplify" the string sound, but it is passive adds no energy. In reality an acoustic guitar is a "mechanical transformer" that matches the string energy to the impedance of the air for propagation at higher volume - it increases the pressure level much like an electrical transformer can increase voltage. In resonant circuits I need to dig deeper to confirm this, but I can easily imagine a similar relationship where a resonant peak generates higher voltage compared to the input, but with a higher Thevenin impedance. That would be consistent with the voltage gain of a transformer (but as I said, I need to dig into this before I can make that claim with any confidence). If the resonant circuit had only inductances and capacitances then there would be no insertion losses (at least not at DC) but the voltage could still be amplified. I have wondered if this is why in guitar pickup response curves we see so much sensitivity to things like eddy current losses. The peak level is generated with a high Thevenin impedance and can be reduced dramatically when loaded by even small loads ( ).
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Post by sumgai on Sept 10, 2019 19:05:06 GMT -5
OK, OK, I give up, enough already.
Have it your way, both of you.
sumgai
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Post by thetragichero on Sept 12, 2019 8:09:24 GMT -5
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Post by newey on Sept 12, 2019 21:18:23 GMT -5
It sure is shiny . . .
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Post by blademaster2 on Sept 13, 2019 9:25:32 GMT -5
... which is a sign of excellent soldering workmanship.
Good job, and beautiful layout.
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Post by thetragichero on Sept 30, 2019 0:23:36 GMT -5
planning stages of something I've wanted/needed for awhile: combination high pass filter and compressor (technically two that are switchable) for my bass board that gets plugged in di. my old plastic dano compressor just isn't cutting it. ends up clipping in a way that doesn't sound great for otherwise clean bass. guessing the hpf will get rid of low frequency transients that could be part of the problem, but having two well-regarded compressor circuits should be helpful too. one is based off the Dan Armstrong orange squeezer and as far as i can tell the engineer's thumb is an original circuit based off the lm13700 ota. to save space i figured I'd use dual gang pots and fiddle with their values/tapers with resistors. i feel like the hardest part will be figuring out how to get everything in the box so I'm figuring that out before i even heat the iron (i usually build it on perf and then figure about drilling and knob placement, etc
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Post by blademaster2 on Oct 7, 2019 21:41:36 GMT -5
In August I completed a nut replacement for an Epiphone Les Paul for a friend's son, but no photos and it already went back to the owner (it turned out really well, and is better now with the bone nut than the plastic one that came with it). More recently I decided to re-install the frets on my first guitar, sort of a celebration for its 40th birthday (now I feel old ...). The original frets were too loose because I had not cut the slots myself and the luthier who did it for me assumed I would glue them in. As a result it played well, but the frets never seemed 'solid', and over its age the fret profile changed and the fingerboard probably settled and I would get choking on the high notes here and there. Also, as I hand-sanded the radius by eye as a teenager I have found it is too round (tighter than 7.25" especially at the nut) and I also noted that it was a compound radius that I created even before I knew what that was called. I also did not flat-file it but rather attacked each buzz one-by-one with a file. There is a lot of sentimentality tied up with those frets, all hand-filed and shaped, so I thought I would first try removing and *reinstalling* the same ones (since they gripped so lightly they came out with no bending and very little wood chipping!). Here is the process I followed: 1) Remove the frets and keep them in sequence 2) Clamp the neck to be held as straight as possible 3) Re-shape/resurface the fingerboard using a 7.25" radius sanding block (StewMac product). This was my chance to remove the slight ski-jump that formed at the high frets due to the need to shim the pocket when the neck goes back in (it was never shimmed, but there was a tongue on the end of the neck that rested on the body surface and might have caused the skip-jump to form, so a shim will remove that pressure and it will hopefully remain with the profile I created) 4) Snip off the very edges of the fret tangs so that I could used wood-filler at the ends, and shed less blood from sharp fret ends. This involved a SteMac fret tang nipper 5) Crimp the fret tangs so they would go back in tighter using a fret tang crimper (another StewMac product) and Hand-bend these frets to match the new, fixed radius. 6) Use the brass, 7.25 radiused fret press insert with the plastic-tipped hammer so that the frets would preserve their radius as they are being tapped back in (yep, another StewMac product) 7) Re-flatten the re-installed frets using the same radiused sanding block and very fine sandpaper. I am in the process of doing this today .... Next steps:8) Make a shim to remove the pressure at the end of the fretboard where it rests on the body when the neck screws are tightened 9) Re-install the neck and (hopefully) discover that the guitar plays great, no buzzing, smooth action ..... I already love the tone from this mahogany-with-inset-maple body and the DiMarzio Dual Sound pickups, so the guitar will be much improved for the *next* 40 years ..... Photos of the process (so far) follow: As the frets came out, only a few minor chips were created and I glued them back. Sanding to reprofile the board took ages since I needed to remove the too-round compound radius to bring it all into 7.25". I considered going flatter but I did not since I wanted to change it as little as possible from my highschool effort. All smooth now with a fixed radius and that lovely, almost perfectly-black ebony. The first few frets have gone back in on the above image and I am very pleased with the StewMac tools and the process I am following. The neck overlaps the body to provide the upper frets, and it looked great but I suspect that there was a small gap in the pocket that created the ski-jump. Perhaps the larger contact area was a good thing for tone but I did not want any more choking on high notes and bends than usual for a 7.25" radius. I can add a shim and try it out, and remove it if I am dissatisfied. Tapping in the frets was pretty gentle, with just-enough tightness after crimping the tangs. I worked hard to match the new radius, so using the brass 7.25" fret-press insert with the hammer preserved the bend during fret reinstallation.
Here is the neck fully refretted, awaiting final truing. I am optimistic that this will improve the playability greatly - and I loved the crisp/warm tone of this guitar already so it will be even better (fingers-crossed)
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Post by thetragichero on Oct 16, 2019 22:34:03 GMT -5
guy sent me some pedals with hope that I'd accept as (partial) payment for some work I'm doing for him. received an interesting delay that looks like it could be fun with guitar, a bass filter/phaser/whatever that demos of it are too over the top... hopefully it's got some more subdued settings or its a hard pass, and a bass di/preamp/od that would be good for church and I'd love for it to replace my rackmount sansamp in my backup rig. only problem is that it's only unity gain (great for sending to FOH but not so great for running into a power amp). so i take a look at the schematic and... aha! a differential buffer on the input. what if i replaced r606 with a 10k resistor and a 100k pot? calculated 11x voltage gain (at max), which should be plenty to get from instrument to line level aaaaand..... we have a winner! (as a side note, i got this stereo power amp and a 2u rack case for next to nothing because channel 1 didn't work.... opened it up and the channel 1 volume pot was no longer attached the the pcb)
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Post by reTrEaD on Oct 16, 2019 23:17:35 GMT -5
what if i replaced r606 with a 10k resistor and a 100k pot? If the 100pF capacitor stays where it is and the right-most terminal remains connected to the output of the op amp, the high frequencies might roll off a bit too much when the gain is at maximum. If you find that to be the case, you might want to put the 100k pot outside that loop (so the 100pF cap bypasses only the 10k resistor) and bypass the pot with a somewhat smaller cap. Maybe 20pF or so.
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Post by thetragichero on Oct 17, 2019 0:08:59 GMT -5
quick testing it seems to work great but just because I'm curious... i plugged 110k and 100pf (10^-4uf) into my rc filter calculator and got about 14khz. is that what you were thinking for cutting highs? I'm okay with being well under that.... in fact one of the things i dig about this di/preamp is that it has a high pass filter... i'd prefer 60hz instead of the 80hz it's at but standing in front of my 1x15 i wasn't losing much low end. this is also intended as a backup for playing live shows that aren't happening yet lol... mainly trying to see how much gear i can shed because i have gone through periods of gear hoarding lol
if i missed something I'd love at least a nudge in the direction of my blind spot
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Post by reTrEaD on Oct 17, 2019 9:41:45 GMT -5
I hadn't done the math. I just saw that cap and figured the purpose was to create a gentle roll off outside the audio range ... to prevent overshoot and ringing. Increasing the resistance would lower the -3dB corner frequency.
If you're okay with it rolling off at 14kHz when at max gain, no worries.
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Post by thetragichero on Oct 17, 2019 10:10:55 GMT -5
okay awesome hope i didn't come off defensive... I was actually eager to confirm that the way i was interpreting it was kosher at any rate, i realized after posting that with the horn switched off (i have my eyes on a sealed midrange driver to replace it as I've seen others do) in that cab, nothing much above about 2.5khz is making it through anyway (that may be why the overdrive sounded a bit dull even with the tone knob cranked... will have to test more)
best part about it is i can now get rid of some more rack gear and this big horkin 6u skb rack case
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Post by thetragichero on Oct 21, 2019 1:40:45 GMT -5
I've never made a rat before (or played one... besides my friend's proco brat when i was 16 didn't sound good with whatever cheap practice amp i had). so here's a rat with a baxandall tone stack (yes it is in the feedback loop of an op amp). quite a bit of tone shaping available with just those two knobs. among other things i shall work on the enclosure tomorrow
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Post by thetragichero on Nov 6, 2019 2:56:54 GMT -5
okay so the build above must've had a spider bridge where it didn't belong or something. ended up being a gnarly gated fuzz. not a rat but a keeper! here is attempt # 2, to be tested in the am
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Post by thetragichero on Nov 6, 2019 10:00:28 GMT -5
now that no one is sleeping i fired 'er up. everything works as expected besides the treble pot lugs being backwards, so apparently my schematic needs to be changed back to what it originally was and not what i changed it to after fiddling on breadboard i don't particularly care for the tone stack. simple high pass filyer like on a stock rat and some sort of bass control would work better unless this needs to push some air instead of being played on my 5watt bedroom amp had a guy order a fuzz a couple months back and i threw in a distortion that i just couldn't get on with on any of my amps. he ended up loving it more than the one purchased
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