new to tubescreamer circuit!! things i noticed when playing with.. questions :)

[ulysses]

hey guys

i built my first tubescreamer clone the other day.. the srv special version..

one question i have is, how does the opamp really affect the sound? the opamp essentially boosts the clean input volume - if you remove the diodes it becomes a volume booster.

i experimented with different diodes and they all had different sounds.. to me it seems the sound really does come from the diodes..

the 1n4148's i used sounded pretty harsh and let a lot more volume through than i suspect the original designer intended..

is there a way to test the diodes i am using to check that they meet the specs of the intened circuit? do 4148's vary from brand to brand?

can anyone recommend any articles on diode selection for the tubescreamer?

i did some hunting around.. buy mostly its just people talking about opamps.. im using a TI rc4558P but i also tried with a TI tl072cp and it didnt make much difference..

cheers
ulysses

[jonathan perez]

someone posted a thread on this, with the sonic differences posted...i cant find it though, anyone got that one in mind?

[m-theory]

I can offer a little bit of personal insight, from my own limited experience on diode selection.  I recently built a GGG T/S with a few standard mods.  I wanted to play around with different diode options, but didn't want to have to solder and de-solder, so I built a daughter board for the diodes and hooked up six different options to a 6P rotary switch. 

#1 is a standard, symmetrical T/S option.
#2 is the same, with an added 1N4001 on one side
#3 is a 1N4001 on one side and 2 red LED's on the other
#4 is a 1N4001 on one side and 2 yellow LED's on the other
#5 is 3 1N914s on one side and 2 1N4001 on the other
#6 is 2 1N4148 and a 1N4001 on one side and a red LED on the other

I also had previously wired up some Ge options, but didn't like them so I replaced them.  They had very weak output and very low gain.  The tone was just fine, but with such low gain and output, I really wasn't interested in them as an option.

This review is a purely subjective opinion, obviously. 

Obviously, there is a noticable difference between these, but I'll try to narrow it down a bit. 

In the Si world, pretty much the "worst" option is the OE version of symmetrical.  Very thin and artificial sounding.  This is what "most" people consider "THE" T/S tone, however, so I put it in there for comparison purposes.  It doesn't do anything at all for me, but then, I've never been a real T/S kind of guy.

Also in the Si world, the asymmetrical options will sound pretty similar to one another.  The difference between symmetrical and asymmtrical, in terms of tone, is pretty significant, although not necessarily earth shattering.  It's still going to be a bit thin, though it will have a bit more output, a touch more bottom, and a LOT more "realistic" tube-like tone and feel.  If a guy really loves the classic T/S tone, but wants an improvement, doing something as simple as replacing one of the 1N914 diodes with a 1N4001 or similar will likely yield very pleasing results for that person. 

Adding an LED or two is where things get really interesting, imo.  Here again, from what I've heard, the options that I created seem to be very similar to one another.  My favorite happens to be #3, 1-1N4001 and 2-red LEDs.  The yellow option sounds smoother, looser, and a bit less articulate to me.  The last option I put in sounds pretty similar to #3, though perhaps a bit looser. 

The general tone with an LED option is definitely what I would describe as "Marshall-esque."  It's big, loud, fat, articulate yet very gainy, and "in your face" a LOT more than Si or Ge options. 

One caveat worth mentioning, with regard to the LED options; they seem to have a dramatic impact on the way that the Op amp works, and some op amps just flat out sounded like crap with my LED options.  The distortion was very unnatural sounding and harsh, even at low gain settings.  At high settings, the distortion got splatty, farty, sloppy, and ugly.  For my LED options, a plain old 4558 seems to work great, although there were a couple others that worked fine as well (4559, 5532, 1458).  The 2262 and 3260E didn't work well at all, though they worked great with Si and Ge variations. 

In a nutshell, if you like Marshall tone, you'll like LED variations (although the diffused 3mm red is probably the best choice).  If you like T/S tone, stay away from this one, and focus on Si options, particularly asymmetrical variations.  If you use LEDs, bear in mind that SOME variations may not work well with certain op amps. 

[studiostud]

I built a daughter board for the diodes and hooked up six different options to a 6P rotary switch. 

Do you have a schematic or photo of how you wired this switch?

[markm]

Just as a side note the Original TS use 1S1588 diodes.
Whether they are tremendously different than 1N914's, I honestly don't know however, I have used them and think they sound good.

[m-theory]

Do you have a schematic or photo of how you wired this switch?

Yes, but I don't know how to upload a file here, so I'll try to explain the best I can.

I built it on perf.  For simplicity, just imagine building one diode variation on the board, rather than picturing 6 or more.  Each one will be built the same way. 

The diodes are laid out in two lines, side by side.  One line should have anodes facing one way, the other line the other.  In other words, for example, if you were to look down line #1, you should see anodes going away from you, and on line #2, they should be coming towards you. 

The ends on each side of the diodes are connected.  One end would be connected to a wire that would connect to the circuit board.  The other would go to one of the positions of the switch.  The throw of that switch would connect to the circuit board. 

If you're hooking up to a 6P switch, you would continue adding diode combinations on the daughter board in the same manner, running an additional wire from each variation line to an additional position on the switch. 

When you're through, you have a switch, a main board, and a daughter board.  From the main board, you have two wires, one of which connects to the throw terminal of the switch, the other of which connects to one end of the daughter board, to which all diodes are connected.  At the other end of the daughter board, you have six wires, one for each diode option on the board, leading to each of 6 position terminals on the switch.  Does that make sense?

You could also solder the diodes and board wires directly to the switch.  That would eliminate the need for an additional circuit board, but it might get a bit cramped on that switch by the time you reach #6. 

Just as a side note the Original TS use 1S1588 diodes.
Whether they are tremendously different than 1N914's, I honestly don't know however, I have used them and think they sound good.

Case in point!  Tone is SO much purely subjective!  I don't know how similar those two are, either, but I never really cared much for the stock T/S sound, which is why I've never gotten around to building or owning one until recently, after reading up on some of the mods and becoming curious.  I'm clearly in the minority on this one, though.  There are about a billion stock tube screamers out there, another billion boutique O/D's based on that circuit, and very few that use LED's as clippers! 

[markm]

Just as a side note the Original TS use 1S1588 diodes.
Whether they are tremendously different than 1N914's, I honestly don't know however, I have used them and think they sound good.

Case in point!  Tone is SO much purely subjective!  I don't know how similar those two are, either, but I never really cared much for the stock T/S sound, which is why I've never gotten around to building or owning one until recently, after reading up on some of the mods and becoming curious. 

I've never tried the 1S1588 in a TS however, I will say the couple of circuits I have put them in seem to sound good.
Don't know if it's "mojo" or not, don't care really either but, It would be interesting to throw a couple of the 1S1588's in the mix and see.

[GibsonGM]

A REALLY neat mod I've done is replacing the clippers in a Blues Breaker with 1 cheapo RS square green LED, and a 914.  Much more 'classic' sounding distortion, IMO, sort of Angus/live Page-ish.  I run that into my  same-box Mosfet Boost that has 2 switchable gain controls....niiiiice   

[markm]

Another idea that may be intersting in a soft clipping circuit like this is MosFET clippers?

[ulysses]

thanks for those replies guys

i much preser the sound of ge diodes in this one, even if there isnt any volume boost..

im going to play around with different si diodes to see if i can get some nice sounds out of them with greater volume.

cheers
ulysses

[Hanglow]

Don't know if this is any use, I saw it on banzai for their "Tubescreamer Chip tuning kit"

# JRC4558D - Classic Tube Screamer Chip
# JRC4558DD - High Gain version of the legendary chip
# RC4558 - made by TI, used in 80s Tube Screamers, sounds warm and soft
# RC4558 (generic) - No name clone of the TI RC4558, sounds edgier than the original
# RC4559 - High Performance dual opamp, used in many quality audio preamps
# LM833N - Low noise dual opamp, known to sound good in Tube Screamer circuits
# TL072 - used in a variety of commercial Tube Screamer clones
# TL072IP - Low noise version of the TL072, more hifi sound
# TLC2272 - increased dynamic range, high drive
# NE5532 - audio opamp, low distortion, high slew rate

[ulysses]

well ive done some more research and some more experimentation

based on my findings that the opamp isnt distorting at all when you take the diodes out, i figured the opamp doesnt play a direct part in the creation of the distortion without the diodes, ie, the opamp doesnt distort on its own like in other circuits like the hotcake..

by playing around with various diodes i figured that some need to be pushed harder than other to get the volume and distortion..

i figured there was a direct relationship with how the opamp was pushing the diodes into clipping.. and that the rc4558p / tl072cp type chips were pushing the diodes way to hard.. and possibly distorting the opamp..

im my personal opinion most opamps sound shit when you push them.

so i checked the various opamp datasheets for output power etc.. tried different ones.. trying to find one that would not distort the opamp

i tried opamps well beyond what the recommended chips are.. about 30 chips later..

what do i think sounds good?
1n34a NOS Ge diodes with rc4558p chip. although it doesnt have any boost the sound is really nice.

what do i think sounds great?
TI Burr Brown OPA2134 High Performance AUDIO DUAL OPERATION AMPLIFIER with 1N4148 diodes.

geez, i hope i didnt just put any tubescreamer replicator clone companies out of business   j/k

*note: i have absolutly no training in this type of thing. any statements were preumtions evaluated through trial and error. dont quote me

cheers
ulysses