Tube Screamer FAQ Version 1

So I've spent some time opening and reassembling the T7 ~ I first A/B'd the two TS7's, found I thought one sounded vaguely (as vague as vague gets) warmer, so I set it aside and got to melting stuff in the other one. I mentioned the 808 swap, but I swapped those resistors back because I was getting a weird static type deal. I swapped the 1 M caps with metal film, and one of them with a Tantalum one. That offered noticeable clarity over the other one. The sound was actually very good. It didn't change the tone, but took away some of the sonic loss or whatever that made it sound cheap. Then I swapped the cap for the bass to .1 and swapped the diodes, though just to similar ones, and swapped more caps to metal film and Tantalum. That really just made things maybe too clear, but still not too far from the original. Then I put in a socket and tried different chips out. All in my opinion, the JRC 072 was very clear, but lacked any character (warmth?), the NTE778A sounded muffled outside of high or low notes, the JRC 4558DD sounded weak (though I probably damaged it in desoldering), and its original 4558D sounded better than the others aforementioned; clear enough, but with what I'm calling character or warmth. Then I got interested in what was in my X60 amp since it had some 4558's spec'd in the schematics. It was like a 4558 roach motel in there. There are 9 TI RC4558P chips in there (from 1987 according their marking and the year of the amp), all in sockets. I tried out one and it was miles above the others ~ fully dynamic and had whatever I think character is. I had to put it back in the amp since I didn't want rob its sound for the pedal's, but I'm now out looking for some of these. In this po-dunk town there's not too much. The local amp repair fellow thinks he has some at home he'll dig up for me. I suppose I can order some online. The TI site doesn't want to send me samples of the RC4558P model.


Next is to mess with the diode combo, though it would nice to put in a switch for that and maybe for the bass hump too. I think I'm going try that mod where you change another two resistors to change the gain range.

Regarding the 'spit' I was looking for, it could be a bit of each thing you mentioned. Noise could well explain what happens after the note, aside from the cycles of the note and the fact that it's overdriven. The picking attack does produce this 'spit', and it could be that at the initiation of the note, the clipping is the most, so once that resolves enough for the note to really appear, it just rings clearer than at its initiation.
 
The 'weird static type deal' shouldn't occur unless you had faulty components or a poor soldering joint.

The 72 is a bit noisy and 'primitive' in a sense... I've never tried the 778... the 4558DD shouldn't have sounded different in any way other than reduced noise (so count on having damaged the thing somehow)... try other chips (OPA2134, NE5532) before settling on the 4558, if you can. Since the 4558 was chosen for convenience and not any kind of technical superiority I wouldn't spend too much time worrying about the bazillions of different 'flavors' of that chip - that's the main thing wrong with that 'Myth Busters' clip posted above... the twits shoved in eleventy billion different versions of the same chip design and plenty of twats out there took that to be conclusive evidence that op amps don't matter. All in all, the op amp changes won't be very big (although noise might change significantly, especially after you've upgraded a few of the other parts) but there is still some slight sense of best and worst.

What would you like to change about the clipping? Before you tamper with the gain range, consider switching to LEDs if you want less clipping or germaniums if you want more. This will change the tone in other ways, but it'll be a bit more sane and it's a little easier to switch out diodes on the fly if you do things right.

That spit is just the clipping from the biggest part of the waveform... to get more, hit the strings harder. You can lengthen it with a compressor or shorten it with an expander (before the TS with careful attention to settings), but that's just clipping for you.

Jeff
 
I think I need to spend some time researching clipping. I know I like harmonics of all sorts, a lot, but I have the lingering question of whether I can really have this pedal do the two things I really want it to do in the same mod. I want to use it before a high gain channel to fill out the sound and help define individual notes while making pinch harmonics sound more pleasant, and hopefully add more harmonic overtones. This it does this stuff somewhat well, outside of a meteor shower of new harmonic tones. The other thing I'd like it to do is create a warm slightly overdriven sound that would work in note laden passages that need to be laid back sonically, not sound processed, while being somewhat dynamic, and through a clean channel ~ which at times it seems to do but still seems elusive overall. I think I'll stop at where it is and start doing more experimentation with how it's reacting with the X60 amp instead of testing it out on my solid state amp so often.

The only thing I've done with the clipping stage is replace one of the diodes with an interesting looking blue striped one I found in an old Japanese component radio I picked up at the local junk store for part harvest. It sounds very good as is, pretty strong, even and clear note-wise. Probably a good stopping point for now.

Incidentally, there's a nearly useless video on you-tube of a step by step mod job, sans specific values, of the TS7 that someone posted which must have been included with a mod kit. It does give some good suggestions on fixing a board thats had the trace collar, or whatever its called, pulled up (I retract my suggestion of wick fraying, by the way; that can be its own disaster). he guy pulls all the connectors off, which I wouldn't imagine doing. There's really a ton of info online, to take back my earlier statement of not being able to find specifics. I wish I had gotten into this years ago.

The biggest lesson seems to be that the music equipment industry isn't set up to really cater to musicians, otherwise all of this modification shit would be more commonplace, in every crummy music store you hopeful-ly pop into.
 
Turns out the guitar player on that Beck song was Jason Faulkner and from what I've found he uses a compressor and your thoughts on compression and clipping, while logical anyways, point to where his sound is coming from.

I tried the Germanium diodes, but the fast cycling sound of the clipping was too much. After trying some more chips, both pre and post 4558 incarnations, it's become obvious why there's so much to-do about the 4558, since it is the happy middle-ground in fidelity for this application.

The local amp guru fellow suggested taking 4 diodes, two going each way, and using alligator clips on either ends of selected diodes to form an opinion about asymmetrical clipping.

He did though have a cryptic warning about pedal and amp mods though. He said he started in his teens, ended up getting an engineering degree to further pursue it and now makes original circuits from the ground up. His warning was that since every single component you change, and their location on the board, the value, the material and the brand will change the sound somehow, you'll be sucked in and all of your time will be devoted to it and everything else, including just playing your guitar will go by the wayside.
 
The 4558 isn't in the middle ground unless your 'low fidelity' reference is a bunch of sticks pasted together with unicorn droppings.

The option I'd go for instead of alligator clips is a switch configuration. It only takes a SPDT to flip another diode in, and once you hear the comparison (note that the volume will be slightly higher) you'll know more about what's ahead.

His warning is correct unless you're even more obsessed with something else from the start. Almost everything you change will have an effect on the sound, and that's quite addictive after a while, but it's possible - even if difficult - to make it through this hobby unharmed.

Jeff
 
The bunch of sticks held together with unicorn droppings is a MC1458N chip. Aside from that I tried a LF353N BIFET that boosted the output but seemed to reveal that it didn't color the sound enough for perceived warmth but it seemed to make me want to play at a million miles an hour which might be something in itself. The NE5532 sounded pretty cheap also, though not as cheap as the MC1458N. I've got some 4558p's on the way and have just gone back to playing and am finding the TS useful all around.

As low cost as the TS7 is I have to say that I might have been more pleased with another version. I used a TS9DX and it sounded sweeter overall. Although the circuit of the TS7 is similar to the TS9 or 808 they aren't the same. Your argument is valid in the realm of dollars to donuts, but apart from building one's own, there's still a lot of relevance to A/B several of the same and different versions and spending some more bucks if what you hear is what you like. The subtleties are there and in that lies the question of whether that matters to the player.
 
What did you think of the OPA2134?

You've missed the entirety of what I said about component variances if you're thinking that the TS7 and the TS9 (at least in the 'usual' mode, not + or Hot or Bacon or whatever else they're tacking on) are different pedals just because one of each that you tried had different sounds. I strongly recommend rereading that. The circuit designs are the same, but of course there will be different components in each pedal - you're very likely to find a 'sweet' sounding TS7 all the same, the differences you're hearing are not because the TS7 and TS9 are different circuit designs.

Jeff
 
I read your business about components et. al., and not be contrary outside of human nature but if the TS7 and TS9 are the same circuit, why is there a Zener diode right in the middle of the TS9 board that doesn't appear anywhere on the TS7?
 
http://www.ibanez.com/parts/2004_PARTS/electronics/others/tubescreamer/ts9/TS9.htm

board layout
http://www.ibanez.com/parts/2004_PARTS/electronics/others/tubescreamer/ts9/ts9_2.pdf

Each of these specify this but it appears it might be related to its switch.

Here's a familiar site
http://www.geofex.com/Article_Folders/TStech/tsxfram.htm

Beyond digging through a part by part match up, there also a significant difference in simple distance through the lengths of tiny wires and across 3 boards that unquestionably will deteriorate tone. The newest TS808HW shows an obvious attempt at economy of circuit length. I just think there could be an inherent set back to the TS7 in its design, that even with the exact same components swapped it wouldn't sound the same. Just ask your guitar cords.

I just think absolutes, like saying the TS7 has the exact same circuit would be well avoided by a man of science. It just closes the door on discussion, like creationism or Rush Limbaugh.
 
That may explain it, I ignore switching because it's not (at least in theory) touching the sound directly.

I actually do have to question the tone deterioration you're claiming. Some immeasurably small deterioration might exist but that's being more than overshadowed by other parts of the pedal. I wouldn't consider that at all, but if you want you could easily streamline things and see if it makes even the slightest difference.

If the absolute statement I made wasn't verified by both schematics and experience with countless of each make of pedal, I would certainly avoid it - but, as a man of something related to science, if both theory and practice point to some phenomenon then I have no choice but to believe in it.

Jeff
 
By PEQ I assume you mean some sort of equalizer. Keeping in mind that everything that isn't around 700Hz gets cut away (by an amount proportional to its distance from 700Hz), what you're looking for is some 'pointy' thing that peaks at 700Hz. The details depend on your equalizer, just start there and find something that helps things cut through a bit.

(CLARIFICATION: This will only approximate the equalization done by the pedal - no clipping, and thus no compression, goes on here.)

The second source used in that article is a bit more in-depth, and I believe I posted it earlier. Still, it's useful.

Jeff
 
great thanks, I have an Axe-Fx Ultra so I can dial in a low/high pass above and below 700. It sounds like there wouldn't be much signal left after that? Not that I've ever tried this before so what do I know, lol. I'll give it a go. Thanks again
 
You can boost the signal afterwards. The EQ is far from being the only thing going on, though, so I wouldn't settle for that.

(Doesn't the Axe-FX have some sort of TS emulator built in? If not, does it really make sense to spend two grand on a modeler but hesitate to spend $20-30 on a used TS?)

Jeff
 
JBroll said:
You can boost the signal afterwards. The EQ is far from being the only thing going on, though, so I wouldn't settle for that.

(Doesn't the Axe-FX have some sort of TS emulator built in? If not, does it really make sense to spend two grand on a modeler but hesitate to spend $20-30 on a used TS?)

Jeff
Click to expand...

Yea it does have a Tube Screamer emulation. I was just really interested in seeing how the EQ effects the tone first to understand that better. Plus they are about to release a Firmware update that will change the parameters of the stopbox emulations so I'm waiting for that before I dive into their 808.
 
well they updated my Axe-Fx firmware and the TS808 emulation. So I poped it in. And I'll tip my hat to you JBrol, great advice! Just placing the 808 in front with no real boost really improved the guitar tone. It's clearer and tighter. Thanks a lot!
 
Thanks to JBroll and also rsf1977- I have joined the TS brigade with a TS9 (store didn't have TS7 on hand) and I'm very pleased with the result.
I'm also a plugin programmer (doing audio units for Logic- Airwindows) and the 'Tube Screamer's Secret' link is all kinds of interesting to me... I've already implemented a similar effect in a tube plugin, 'Hard Vacuum', and now I'm very interested in doing a plugin version of the focussing effect this pedal gives. I'm going to have to run some tones and things through it and see what it does :)
 
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