Orange Drop Caps vs. Ceramic Disk?

[Steve Conner]

Chuck hangs out with Dan Torres and Dean Markley! Soon he'll be opening a crack house

I always wondered what dielectric the old ceramic discs are made of. Pretty sure the 100s of pF values are NP0/C0G, but what about the bigger ones?

[Steve A.]

g40v_mod.pdf

But of course my mind is open, I'd *love* to see some original, classic circuit and then some, say, "[insert Guru name here] Mod" which makes it sound better.
Preferrably 3 or 4 examples, so as to show that 1 was not just a lucky chance.
I'm all ears

For starters there was the Dan Torres "Triple Killer" mod for the BF/SF amps. The cathode of the first stage had a center-off SPDT mini-toggle switch for different values of Ck- 22uF/no cap/0.68uF to switch between BF, super clean and Marshall-like sound. I posted the specifics several times on AMPAGE. I don't think that trick was very widely known or used back then (15+ years ago.) I liked it better with some capacitance in the center off position so it was more like 22uF/.068uF/2uF. I also used a DPDT switch to change the Rk resistors as well.

He showed how wire up power tubes with triode/pentode and cathode biased/fixed bias switching which wasn't anything revolutionary, and how to convert AC heater voltage to DC and to add bias adjustment pots to amps that didn't have them. I used all of those tricks in my mods for the Pignose G40V in 2000:

g40v_mod.pdf

He had a lot of mods which I didn't try like his "Prince Tone" mod for the Princeton Reverb amps which I believe was original with him. He lists a much simpler mod on his site called the "Perfect Prince" which adds a bias adjustment pot among other things.

As for his errors in understanding electronics he was taken to task for his definition of Class A- he said that cathode bias made an amp Class A. But other than that there weren't that many big glaring mistakes in his writings. Back then there were certain people who would attack Dan on-line whenever his name was brought up- and even when it wasn't. It seemed like a few people had a personal vendetta against him. I must admit that there was work that came out of his shop that didn't look very professional and people would upload pictures of them. (He has had assistants who did a lot of the work but I think that the general feeling was that no one was going to pull out the chassis anyway so what the heck...)

If nothing else Dan got a lot of people interested in modding and building guitar amps.

Steve Ahola

P.S. His articles in Vintage Guitar- I don't believe any (or most) of the VG columnists were paid for their articles. Instead of money they would receive a stack of magazines that they could sell in their shop. That is my own theory based on the observation that he usually had a stack of the current issue on his counter- the only magazine that he sold. But the biggest benefit of his VG articles was the publicity.

[dai h.]

Chuck hangs out with Dan Torres and Dean Markley! Soon he'll be opening a crack house

I always wondered what dielectric the old ceramic discs are made of. Pretty sure the 100s of pF values are NP0/C0G, but what about the bigger ones?

these days it seems you can buy larger value (10nF to about 100nF) temp. compensating ones (esp. in SMT package) easily (RS components, etc.), but I seriously doubt the big (10s of nF range) ones in old amps were temp. compensating types. The smaller ones, I think they could be either (at least for Marshalls) with the size giving a big hint even if there are no specific markings (smaller = probably non-temp compensating).

[J M Fahey]

Dear Steve.
First of all, I'm not personally dissing Dan Torres at all; as you can clearly see I cut and copied that line from Chuck H's post #9 .
2) As of the "triple killer mod" I don't see him contributing much more than a cool name; using a .68uF cap (meaning "let's cut some bass to improve distortion") instead of 10uF ("let's pass all, anyway this amp will be used clean"), in due justice should be called "the Jim Marshall mod" (or maybe "the Ken Bron mod", who knows?).
So it turns a widely known and respected classic amp into another widely known and respected classic amp. Which is the news, actually?
3) same about switching between fixed bias and and cathode bias.
4) In fact, in this particular case, I recognize "Dan Torres mods" to sound good, *because* they simply go from one

original, classic circuit

to another.
Where to boot the second one is historically a derivation from the first .

I *do* recognize that there are good, revolutionary "mods" .... only I always find them in classic commercial amps, go figure.
Such as when Marshall turned a Tweed into ... a Marshall.
When Marshall cascaded 2 gain stages (previously used in parallel) and gave us JCM800.
When Mike Soldano turned a JCM800 into an SLO 100
When Randall Smith added an extra triode and turned a Twin into a Mark1
and so on.
Sorry if I fail to find similar originality *and* good sound in guru mods.
Generally it's either one ... or the other.
Oh well, maybe 43 years doing this turned me into a cynic .... or should I say a realist?
Anyway, never there was intention to despise anybody, not my style anyway, amd if something I said sounds so to somebody, my apologies.

[Chuck H]

When Randall Smith added an extra triode and turned a Twin into a Mark1

FWIW Dan was actually doing this at about the same time as Randall. The hi/low input jacs were replaced with switching jacks. Plug into one and you had the standard Fender vibrato/reverb channel. Plug into the other and you had an extra triode stacked in front. Later on (in 1989) he started calling it the "Hot Fender" mod. It was one of his first.

Dan got's a few things a little wrong. He's even published circuits that have been operationally questionable from a technical standpoint (though they all worked). But Steve makes the best point on the issue. Dan was introducing stuff to the public that previously was only available from select shops. He's a bit pontificant too. Which doesn't help. If your going to strut like a rooster someone is bound to get up in your grill. But Dan deserves his kudos for being one of the original players. He was schooling guys on how to improve their amps thirty years ago!!! Way ahead of the trend. And as I said before... You can scoff at the details (and even "I" do) but for the most part his circuits work to help players get the sounds they want. He's been doing it as long or longer than any of us, and with way more light on him. Sure, at this point even "I" could look at some of his circuits and say "That shouldn't be like that" or whatever. But there haven't been any glaring problems that I know of. But there have always been a couple of things about his promotion jibe that always troubled me...

The most memorable one being that he used to advertise his Torres "patended midrage control". Now, that was so long ago that the patent would be over by now. But the fact is that the circuit was almost identical to one used by Gibson ten years earlier! Of course, he never said it was HIS patent on the circuit. He just said it was patented.?.

P.S. Steve C, my association with anyone noteworthy is almost strictly a result of the fact that I came up in the San Francisco Bay Area. Which enjoyed it's greatest pop/rock music contributing era when I was in the game. So it's just a matter of sheer exposure. Could have happened to anyone in my shoes. And probably should have. But crack could be a good investment right now. I'll consider it.

[soundmasterg]

Chuck hangs out with Dan Torres and Dean Markley! Soon he'll be opening a crack house

I always wondered what dielectric the old ceramic discs are made of. Pretty sure the 100s of pF values are NP0/C0G, but what about the bigger ones?

Most of the Valco amps like the Supro T-bolt used those big old ceramic discs as coupling caps, and they sound great. A lot of the raw grittiness to their tone can be traced to those caps. They do sort of make the amp a one trick pony though. I've heard that the old, larger ceramic caps sound better than new manufacture but have not tried anything yet....partly because I am still trying to get enough of the old ones at surplus places to try out in an amp.

Greg

[J M Fahey]

FWIW Dan was actually doing this at about the same time as Randall.

Cool. Nice to know.
By the way, I am a firm believer in "parallel" discovery or invention, meaning same thing being almost simultaneously developed in far away places, without the least connection between them.

[Steve A.]

Dear Steve.
First of all, I'm not personally dissing Dan Torres at all; as you can clearly see I cut and copied that line from Chuck H's post #9 .
2) As of the "triple killer mod" I don't see him contributing much more than a cool name; using a .68uF cap (meaning "let's cut some bass to improve distortion") instead of 10uF ("let's pass all, anyway this amp will be used clean"), in due justice should be called "the Jim Marshall mod" (or maybe "the Ken Bron mod", who knows?).

When Dan introduced that mod I don't think that any of the amp mfgs were doing that trick- using a switch to toggle between Fender values, Marshall values and a lower gain value. Is there anything really new under the sun? Good amp techs knew a lot of tricks like that but they worked for pros not the common folk. Back then amp techs were almost like the guild of magicians who would excommunicate you if you gave away any of their secrets. If you kept your tricks to yourself they would be more valuable to you.

Torres and Weber in their books gave away some of those amp tech tricks that everyone had been so tight-lipped about before. Times have changed and ALL sorts of information about guitar amps and mods are readily available on-line but it wasn't like that before.

Almost every time I'd go into Dan's shop he'd show me some new design or mod that he was working on. Nothing earth-shattering but then again how often do we see features in new amps which rock your world? Good amp techs knew how to wire up fixed/cathode bias switches but it couldn't have been that well known since Sal Trentino was able to patent it in 1995:

Patent US5546046 - Output tube bias selection apparatus for tone alteration in a tube-type ... - Google Patents

Steve

[Bruce / Mission Amps]

....

Almost every time I'd go into Dan's shop he'd show me some new design or mod that he was working on. Nothing earth-shattering but then again how often do we see features in new amps which rock your world? Good amp techs knew how to wire up fixed/cathode bias switches but it couldn't have been that well known since Sal Trentino was able to patent it in 1995:

Patent US5546046 - Output tube bias selection apparatus for tone alteration in a tube-type ... - Google Patents

Steve

Sal Trentino was a pretty cool guy and when I talked to him about this patent back in the mid late 90's, he told me it would only be annoying him if the big amp companies used it with out his permission... he said he didn't care at all about us little folks and the home brewers.... more power to them.
God rest his soul...

[Chuck H]

No disrespect intended... But what's patent-able about a fixed/cathode bias switch. I think that mod has been discovered repeatedly by tweaks that never saw a working example before and I'm pretty certain a prior art could be found to defeat any such patent. Maybe I should run to the patent office and try to lock up the notion of a NFB lift switch!?! Just sayin'.

[kleuck]

To us (Europeans) it often seems that in the US there's always someone to patent everything in the world, from the human DNA to the name of ancient native populations, would be hilarious, but it seems there is always someone to accept these stupid patents. Follow the link, a patent for a PPMV ! Do someone have a patent for the guitar pick ?

[Steve A.]

Sal Trentino was a pretty cool guy and when I talked to him about this patent back in the mid late 90's, he told me it would only be annoying him if the big amp companies used it with out his permission... he said he didn't care at all about us little folks and the home brewers.... more power to them.
God rest his soul...

I learned about his patent right after I had written up all of Torres-inspired mods for the Pignose G40V including the fixed/cathode bias switch. So I sent him an email asking if he wanted me to delete that section from the article and like you said had no problem with the little folks like us. Very cool guy!

Steve