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what is Pro/SuperTexan

1/2/1998 11:17 PM
Stephen Delft	what is Pro/SuperTexan I saw in Steve A's recent reply, a reference to "Pro/Super Texan" I've obviously been out in the bush too long..."Pro" I understand, but could you fill me in on "Super Texan" please. ( Whatever it is, I hope you have GC's in there > I am puzzled that you report it sounds better at 30mA idle current. Is that for both tubes? Even if 6V6's ( taking a chance at 473V) it seems rather low. Certainly low for 6L6's. Some Twins were set up for about 20mA each tube and when they come in for retubing I think they sound better with a bit more than that. So I am very curious about what kind of thing is your Super Texan...and under what circumstances 15mA at 470v would be optimum working conditions. - Stephen

1/2/1998 11:17 PM

Stephen Delft

what is Pro/SuperTexan

I saw in Steve A's recent reply, a reference to
"Pro/Super Texan" I've obviously been out in the bush too long..."Pro" I understand, but could you fill me in on "Super Texan" please. ( Whatever it is, I hope you have GC's in there :-)

>
I am puzzled that you report it sounds better at 30mA idle current. Is that for both tubes? Even if 6V6's ( taking a chance at 473V) it seems rather low. Certainly low for 6L6's. Some Twins were set up for about 20mA each tube and when they come in for retubing I think they sound better with a bit more than that.
So I am very curious about what kind of thing is your Super Texan...and under what circumstances 15mA at 470v would be optimum working conditions.
- Stephen

1/3/1998 4:25 AM
Steve Ahola	Stephen: My "Pro/Super Texan" is an old butchered-up '65 Pro Reverb amp which I resurrected by putting in the Dan Torres SuperTexan point-to-point circuit board. The transformers, choke, and power supply filter caps are all original (hence the B+ of 473vdc), but practically everything else is new, and of the Torres ST design (basically a tweaked Fender, with an added gain stage in the OD channel ala Mesa Boogie). His book on tube amps recommended a bias current of around 25mA (per 6L6GC tube) for a B+ of 473vdc. Most of the posts here at AMPAGE recommend a bias current of at least 31mA for Class AB, but I think they may have a lower B+. I tried out bias currents between 31 and 35mA for 3 matched pairs of output tubes, and found the best values for my ears to be around 28.5mA for fixed bias and 29.7mA for cathode bias. The formulas in Dan's book for determining the cathode bias resistor didn't work right, so I just experimented with 3 or 4 different values and ended up using 2 resistors adding up to 775 ohms. The only complaint I've heard about cathode bias is that it has a lower volume than fixed bias; I got around that by setting the fixed bias pot to produce a bias current approximately 1.2 mA lower than in the cathode bias mode. Steve Ahola

1/3/1998 4:25 AM

Steve Ahola

Stephen:

My "Pro/Super Texan" is an old butchered-up '65 Pro Reverb amp which I resurrected by putting in the Dan Torres SuperTexan point-to-point circuit board. The transformers, choke, and power supply filter caps are all original (hence the B+ of 473vdc), but practically everything else is new, and of the Torres ST design (basically a tweaked Fender, with an added gain stage in the OD channel ala Mesa Boogie).

His book on tube amps recommended a bias current of around 25mA (per 6L6GC tube) for a B+ of 473vdc. Most of the posts here at AMPAGE recommend a bias current of at least 31mA for Class AB, but I think they may have a lower B+. I tried out bias currents between 31 and 35mA for 3 matched pairs of output tubes, and found the best values for my ears to be around 28.5mA for fixed bias and 29.7mA for cathode bias. The formulas in Dan's book for determining the cathode bias resistor didn't work right, so I just experimented with 3 or 4 different values and ended up using 2 resistors adding up to 775 ohms. The only complaint I've heard about cathode bias is that it has a lower volume than fixed bias; I got around that by setting the fixed bias pot to produce a bias current approximately 1.2 mA lower than in the cathode bias mode.

Steve Ahola

1/6/1998 11:37 PM
stephen	Steve, Re: "Super Texan" I didn't know the name. I haven't seen any of the Torres mods ( although I've seen plenty of comment about them in a.g.a. and elsewhere. Opinion seems to be er...divided Stephen

1/7/1998 12:49 AM
Steve A.	Stephen: >>> Opinion seems to be er...divided <<< That's a tactful way of putting it! Compared to the other amps I have owned, I _was_ very impressed with the SuperTexan mod I did last year and finally got around to putting in silver mica caps last weekend. I had done a lot of tweaks to his circuit and thought I better look them over to see exactly what I had done. I also tried out several combinations of tubes to see what effect they would have. Bottom line? The SuperTexan Clean channel is very nice (especially with a touch of reverb), although you don't want to crank it up much more than 7 or 8. (The Clean channel is virtually identical to his Reverb King amp that was reviewed in the Guitar Player roundup of boutique amps last February.) The OD channel has some nice smooth "dirty" overdriven tones, but it just doesn't have the CLEANER overdriven tones that I've been able to get out of a Peavy Classic 30 that I just modded. While I may experiment around with Dan's circuit a little bit more to see if I can clean it up to my own personal tastes, I think what I will eventually do is a total redesign of the OD channel, basing it on a '59 Bassman with an added gain stage that can be switched on for some Marshall-like sounds. If I can get that design off the ground, it will be one KILLER amp: BF Super tones (ala Mike Bloomfield) on the Clean channel, tweed bassman tones (ala Albert King) on the basic OD channel, and some mildly-distorted Marshall sounds (ala Eric Clapton/BluesBreaker) on the boosted OD channel. I already have several switching options for the output section (cathode/fixed bias and pentode/triode) which should work well with the different preamp modes. While I may have some mixed feelings about the SuperTexan mod, I have to say that Dan is a walking encyclopedia of tube amp mods! Steve Ahola

1/7/1998 12:49 AM

Steve A.

Stephen:

>>> Opinion seems to be er...divided
:-)

<<<

    That's a tactful way of putting it! Compared to the other amps I have owned, I _was_ very impressed with the SuperTexan mod I did last year and finally got around to putting in silver mica caps last weekend. I had done a lot of tweaks to his circuit and thought I better look them over to see exactly what I had done. I also tried out several combinations of tubes to see what effect they would have.

    Bottom line? The SuperTexan Clean channel is very nice (especially with a touch of reverb), although you don't want to crank it up much more than 7 or 8. (The Clean channel is virtually identical to his Reverb King amp that was reviewed in the Guitar Player roundup of boutique amps last February.) The OD channel has some nice smooth "dirty" overdriven tones, but it just doesn't have the CLEANER overdriven tones that I've been able to get out of a Peavy Classic 30 that I just modded.
    While I may experiment around with Dan's circuit a little bit more to see if I can clean it up to my own personal tastes, I think what I will eventually do is a total redesign of the OD channel, basing it on a '59 Bassman with an added gain stage that can be switched on for some Marshall-like sounds. If I can get that design off the ground, it will be one KILLER amp: BF Super tones (ala Mike Bloomfield) on the Clean channel, tweed bassman tones (ala Albert King) on the basic OD channel, and some mildly-distorted Marshall sounds (ala Eric Clapton/BluesBreaker) on the boosted OD channel. I already have several switching options for the output section (cathode/fixed bias and pentode/triode) which should work well with the different preamp modes.

    While I may have some mixed feelings about the SuperTexan mod, I have to say that Dan is a walking encyclopedia of tube amp mods!

Steve Ahola

1/7/1998 7:26 AM
Bob K.	My two cents about the Super Texan mod: I did the mod on an 80's channel switching Fender Concert but only the OD channel mod. The clean channel, reverb, driver and power amp section is stock AB763. I did not add the effects loop. I did change the parts and values in the ST OD channel to "stock" Fender values. My impression of the mod? It works for me. It does what I wanted it to: gave me a BF clean (and stays clean) channel and a "Hellcasters" type sound OD channel. It works and it sounds great for the music I play. I am working on one more modification though. I love the clean and OD channels as they are right now. They sound great and are very useful. What I am missing is a higher gain, more sustain (ala Boogie)sound. I am presently working on adding this sound to become the 3rd channel. "Tone" is subjective. The ST mod will not suit everyone's taste or style. It does suit mine though.......at least for now. Bob

1/7/1998 7:26 AM

Bob K.

My two cents about the Super Texan mod:

I did the mod on an 80's channel switching Fender Concert but only the OD channel mod. The clean channel, reverb, driver and power amp section is stock AB763. I did not add the effects loop. I did change the parts and values in the ST OD channel to "stock" Fender values.

My impression of the mod? It works for me. It does what I wanted it to: gave me a BF clean (and stays clean) channel and a "Hellcasters" type sound OD channel. It works and it sounds great for the music I play.

I am working on one more modification though. I love the clean and OD channels as they are right now. They sound great and are very useful. What I am missing is a higher gain, more sustain (ala Boogie)sound. I am presently working on adding this sound to become the 3rd channel.

"Tone" is subjective. The ST mod will not suit everyone's taste or style. It does suit mine though.......at least for now.

Bob

1/8/1998 3:49 AM
Steve Ahola	Bob: >>> I did change the parts and values in the ST OD channel to "stock" Fender values.<<< >>>What I am missing is a higher gain, more sustain (ala Boogie)sound.<<< Do you remember which parts you changed? Like the tone caps and coupling caps? (Super Reverbs used a 250pf treble, a 0.1uf bass and a 0.022uf mid cap which sounds really nice in the ST clean channel.) Or the grid load resistors, too? (He uses 220k for the 3 stages in the OD channel, Fender used 100k.) As for the 3rd gain stage in the OD channel, did you change any parts there? (the BF Fenders never had that 3rd "Boogie"-style stage so I'm wondering what mods you did to it). >>>What I am missing is a higher gain, more sustain (ala Boogie)sound.<<< With the ST OD channel as designed (at least the version I got in 9/96), there is perhaps too much gain and sustain for my own tastes and I'm trying to tone it down a bit. It's not that I don't like the Boogie sound, I'd just rather have a more authentic overdriven Fender sound- if I could have both options (as you suggest for a 3 channel amp) it'd be even better. >>>I did not add the effects loop.<<< Maybe you got a different version of the ST than I did, because the tube-buffered effects loop is part of the preamp gain circuit in the ST mod for the version that I got. Or did you hook the tube up and just omitted the jacks? I'd like to eliminate the FX loop and tube stages, too, but there would be a substantial gain loss. Bob, if you remember how you modded the ST OD channel, let me know as I am in the process of reworking the OD channel for less gain. Steve Ahola

1/8/1998 3:49 AM

Steve Ahola

Bob:

>>> I did change the parts and values in the
ST OD channel to "stock" Fender values.<<<
>>>What I am missing is a higher gain, more sustain (ala Boogie)sound.<<<

Do you remember which parts you changed? Like the tone caps and coupling caps? (Super Reverbs used a 250pf treble, a 0.1uf bass and a 0.022uf mid cap which sounds really nice in the ST clean channel.) Or the grid load resistors, too? (He uses 220k for the 3 stages in the OD channel, Fender used 100k.) As for the 3rd gain stage in the OD channel, did you change any parts there? (the BF Fenders never had that 3rd "Boogie"-style stage so I'm wondering what mods you did to it).

>>>What I am missing is a higher gain, more sustain (ala Boogie)sound.<<<

With the ST OD channel as designed (at least the version I got in 9/96), there is perhaps too much gain and sustain for my own tastes and I'm trying to tone it down a bit. It's not that I don't like the Boogie sound, I'd just rather have a more authentic overdriven Fender sound- if I could have both options (as you suggest for a 3 channel amp) it'd be even better.

>>>I did not add the effects loop.<<<

Maybe you got a different version of the ST than I did, because the tube-buffered effects loop is part of the preamp gain circuit in the ST mod for the version that I got. Or did you hook the tube up and just omitted the jacks? I'd like to eliminate the FX loop and tube stages, too, but there would be a substantial gain loss.

Bob, if you remember how you modded the ST OD channel, let me know as I am in the process of reworking the OD channel for less gain.

Steve Ahola

1/8/1998 7:22 AM
Bob K.	Steve, True story: About 3 years ago I bought a used RI Twin Reverb. After reading about the Torres mods I called and asked if he could do a ST in a RI Twin. He told me that while he had never done one on a RI before he could pull everything (the PC board) and, starting from scratch, rebuild the amp. It took a while, and many phone converstions)to get the amp back but I finally did. He told me that his experience about converting a RI Fender from PC board to pt-to-pt wiring would be good source material for his column in VG Magazine. He did right the article. Mine RI was the first one he ever put and ST mod into. Why do I mention this? Because I really didn't like that ST mod at all and eventually sold the amp. In May '97 I had occasion to be out in San Francisco area (I live in Connecticut) and made it a point to stop in to Torres' shop. I introduced myself. He actually did remember me. Anyway at that time ehe told me that he had made many changes to the ST mod and it was completely different that the ST mod he put in my amp way back when. That's why I gave the mod a second try and it does sound different and, to me, much better. I don't know what "version" of the ST mod you have. But to answer your questions: The tone stack is 250pf, .1, .047 with a 100K slope resistor. The anode resistors are all 220k (no change). The cathode resistors are: 2.2k with a 22mfd bypass cap, 2.2k with a .47 bypass cap (Torres calls for a 4.7mfd cap), 2.2k with a .68mfd connected to a 10k which is connected to ground. The Effects loop: Fender uses 1/2 of a 12AX7 to "mix" the dry and reverb signals back together prior to the driver. Torres changes a couple of values around but essentially he uses this 1/2 as an effects send, uses another 1/2 of a 12AX7 as the return buffer and then send the signal to the driver. I kept this "mixing" stage before the driver stock and never added the return buffer. If you want to swap copies of ST schematics let me know and give me a fax number. I can send you an original and one marked up with the changes I made or didn't make. If you know anyone who has a copy of the Torres "Texas Boogie" schematic and wants to swap schematics let me know. I am curious to see what the circuit differences are. Be good. Bob

1/8/1998 7:22 AM

Bob K.

Steve,

True story: About 3 years ago I bought a used RI Twin Reverb. After reading about the Torres mods I called and asked if he could do a ST in a RI Twin. He told me that while he had never done one on a RI before he could pull everything (the PC board) and, starting from scratch, rebuild the amp. It took a while, and many phone converstions)to get the amp back but I finally did. He told me that his experience about converting a RI Fender from PC board to pt-to-pt wiring would be good source material for his column in VG Magazine. He did right the article. Mine RI was the first one he ever put and ST mod into.

Why do I mention this? Because I really didn't like that ST mod at all and eventually sold the amp.

In May '97 I had occasion to be out in San Francisco area (I live in Connecticut) and made it a point to stop in to Torres' shop. I introduced myself. He actually did remember me. Anyway at that time ehe told me that he had made many changes to the ST mod and it was completely different that the ST mod he put in my amp way back when. That's why I gave the mod a second try and it does sound different and, to me, much better.

I don't know what "version" of the ST mod you have. But to answer your questions:

The tone stack is 250pf, .1, .047 with a 100K slope resistor.

The anode resistors are all 220k (no change).

The cathode resistors are: 2.2k with a 22mfd bypass cap, 2.2k with a .47 bypass cap (Torres calls for a 4.7mfd cap), 2.2k with a .68mfd connected to a 10k which is connected to ground.

The Effects loop: Fender uses 1/2 of a 12AX7 to "mix" the dry and reverb signals back together prior to the driver. Torres changes a couple of values around but essentially he uses this 1/2 as an effects send, uses another 1/2 of a 12AX7 as the return buffer and then send the signal to the driver. I kept this "mixing" stage before the driver stock and never added the return buffer.

If you want to swap copies of ST schematics let me know and give me a fax number. I can send you an original and one marked up with the changes I made or didn't make.

If you know anyone who has a copy of the Torres "Texas Boogie" schematic and wants to swap schematics let me know. I am curious to see what the circuit differences are.

Be good.

Bob

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