Diaz Amps

Tube or solid-state, this section goes to eleven!
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KHELSTROM
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Post by KHELSTROM »

Does any one have any schematics? I assume they're derived from Fender circuits but I'm still curious to see how Cesar tweaked them.

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KHELSTROM
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Post by KHELSTROM »

CD-30

Found this video gut shot on youtube. Not very clear but it's something. The owner mentioned in the comments that he planned on tracing it, I'll have to send him an email.

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KHELSTROM
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Post by KHELSTROM »

Just bumping this up since its been a while...

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Post by KindaFuzzy »

Based on the video, very fender, looks like a deluxe reverb circuit with dumble mid boost mods and no tremolo. Could use tighter heater wire twisting, and a little tidying up inside, especially for $5K+.

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tictac
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Post by tictac »

I've worked on a few Diaz amps, not really impressed with build quality. Nothing inovative or original that I can remember; it was basically a Fender with colored tolex...

TT

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teemuk
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Post by teemuk »

As far as I know, the only real catch in (some of) them was having more controls for the reverb circuit (e.g. dwell and tone control) as well as a feature to modulate the reverb's output signal with the tremolo oscillator, sort of to create a crude echo effect. The circuitry is covered in extreme detail in US Patent #5,333,203

Besides that, I think they were very basic amps.

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Post by phatt »

Hi KHELSTROM,
What Exactly are you hoping to find?
If it's that *Texas tone mojo Thang* you are chasing,, you will never find it inside amplifiers as that trick was more likely done *Externally* and has little to do with the Amps.
If that is your interest I'll post it for you?
Phil.

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Mr. SD-1
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Post by Mr. SD-1 »

phatt wrote:Hi KHELSTROM,
What Exactly are you hoping to find?
If it's that *Texas tone mojo Thang* you are chasing,, you will never find it inside amplifiers as that trick was more likely done *Externally* and has little to do with the Amps.
If that is your interest I'll post it for you?
Phil.
Yes, please post.

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mmolteratx
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Post by mmolteratx »

I'm guessing it would be like his 'Diaz mod' to BF Fender amps. An AB763 pre with the vibrato circuitry and normal channel removed. Probably a Dumble or Boogie type tone stack with the tone control switches. Big Twin type power section. At any rate, they're very likely to be Fender AB763 derivatives.

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phatt
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Post by phatt »

Mr. SD-1 wrote:
phatt wrote:Hi KHELSTROM,
What Exactly are you hoping to find?
If it's that *Texas tone mojo Thang* you are chasing,, you will never find it inside amplifiers as that trick was more likely done *Externally* and has little to do with the Amps.
If that is your interest I'll post it for you?
Phil.
Yes, please post.
Hi all, sounds like a few are interested

If you are expecting a rave about Texas Special PUP's and Tube Screamers (TS 9.999999) or a link to some holy grail Amp.
Nope, sorry that's just a handy bit of gossip often used as promotion to sell more crap so big names can make money from ignorant masses who will believe anything they are told in magazine hype.

More likely a simple R/C trick.

First note;
If the back of your Amp has more bottles than a vintage wine rack and the front panel has more switches and knobs that a 747 flight deck then it should be obvious this will not work.

On the other hand if you have a ****STOCK Amplifier*** from the era of SRV then yes you have a very good chance of success.

Though the SRV Amps where many and varied there was *ONE Common in all those Amps* the Input setups where mostly all the same configuration. that being the 68k/68k/1Meg dual input.

So whether you had a Vibrolux, a Super Reverb or a Marshall the inputs where all much the same.
This is what I belive is the KEY.
Or shall I say, **The missing link in texas tone**.

SRV Played LOUD and there is no way you can get *clean and loud* from the Amps he used without the signal turning into MUD.
Understandably people assumed he must have used highly modified equipment.

I say Bollacks; Anyone who believes that crap has only a limited view of how Amplifiers work.

The fundermental mistake (Still made by 100's of Bootweakers today) is MORE GAIN = Better Tone.

It is in fact *The Severe Loss of Gain* that gets that SRV Tone to happen.

Consider this:
At the peak of his carrier SRV had about 40 Amplifiers (often different brands and models) and if you Asked a Teck to rewire them so they ALL developed the same basic **Sonic Signature Tone Shape**? I doubt there would be many takers as Anyone seroiusly versed in Amplification design would decline such an invertation as they would know their chances of success would not be good.

Yet SRV seemed to develop the same signature tone no matter what Amp He played through or what guitar he used.
Hands maybe? Nup sorry that's not tone.
Wood? nup it's an Electric guitar for gods sakes.
TS9? Jezz come on that ones been done to death?

So How on earth was it done??? :hmmm:

Sometimes things seem extremely complex yet in truth the answer is dead simple and This is likely to be the case here.

Simlpy by implimenting **a Single Capacitor** in front of the **low input** forms a passive HiPass Filter. Any Stock Amp of that era is capable of producing the bell like tone of SRV.
This trick turns the Preamp gain *DOWN,,,Not UP* as most hot rod tricks would suggest and in the process rips off all the excess bass and Now you CAN turn All the knobs up full (or close to it) and the Amp WILL NOT Mush OUT from TOO much BASS.

You can’t get this sound any other way, without serious and mostly expensive internal modifications. Modern and Boutique Amps try and do tone tricks inside the Preamp Gain Stages which as most will testify if they are honest,, never quite cut it.

You have to do this *Passive Hi-Pass Before The preAmp circuit NOT inside an Active circuit*

This is simple EQing in the most basic sense and you can now get FULL Power From the Output stage where the power tube compression and power sag can work it's magical effect on sustaining the signal. That IMO is the most obvious way it was done.

The *actual setup* that SRV might have used may have been hidden inside his *Amp splitter box* which was nearly always present but this simple example (See Pic) negates any confusion and does the same job.

Just wire a 1nF or 1n5 cap inside the plug of a guitar cable and use the *LOW Input* on any Fender or Marshall from that era and *Don't use the bright channel on Marshalls* as you are creating your OWN New bright channel by doing this so a bright channel will render it way way to bright.

NOTE; Depending on your taste try from 1nF up to about 3nF past that something is wrong if it does not work for you.

****If you do not play LOUD Don't even bother as it will be dissapointing at low levels*****
You can't do this in any other place And LOOSE GAIN at the same time.
Remember preamp Gain only makes the Amp Distort quicker; it does not make the Amplifier much louder at full Volume.

This trick will at least double the CLEAN headroom before distortion so now the Power Amp can do its magic, This is known as Power Amp Distortion/compression/PSU Sag which is a somewhat cleaner/sweeter sound than all Preamp distortion which is now common place in most any tube Amplifier.

I have no doubt that some Modern Amps are very good but are still vastly more expensive than what
I have presented here.
Go compare the cost of some fancy Amps Claiming great tone and then compare that to the cost of a 1nF Cap and a new plug. you'll spend about $5 with my trick. Cricky a beer costs more!!

Now any half decent Stock Strat will sound like SRV and if it does not work for you it's cost you next to niks to find out.

Hint, the More Bass the Amp Has ,, the better the effect works.

Have fun, Phil.
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Mr. SD-1
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Post by Mr. SD-1 »

Just to clarify... The capacitor is wired in series with the guitar signal?

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Post by bajaman »

Just to clarify... The capacitor is wired in series with the guitar signal?
YES :thumbsup - that is what the schematic shows :roll: :wink:
nice trick :applause:
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Post by phatt »

Yes Bajamans spot on.
And forgot to mention another point that gets missed a lot,, but hey it was all a long time back when I worked it all out. :oops:

Try using 12AU7's in V1 instead of 12AX7's really turns the gain down and helps to keep the power stage super clean all the way to ten. With big amps and speaker boxes it sounds amazing.
Phil.

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Post by fosnal1950 »

Try using 12AU7's in V1 instead of 12AX7's really turns the gain down
Yeah but this could be a bit too much , I would suggest 5751 tubes as V1 . Great tubes for this position if you don't want to go too low in gain.

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Post by DougH »

Nice trick, will be fun to try.

Only thing I slightly disagree about is SRV having a "signature" sound no matter what he played through. I've got a live album of his from before he became famous where he was using a marshall and it definitely sounds like a marshall. Sounds very different than his subsequent "texas tone". Maybe that was before he developed his "signature", whatever...

Looks like a fun trick to try. Will give it a go.

Edit:

Hee-hee! :mrgreen: I just realized it's a slight modification to my "jcm800" version of the "legendary spice":

Image


:mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen:
"You have just tubescreamered or fuzzfaced yourself " -polarbearfx

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Post by phatt »

Hi Doug,
Thanks for the input but you have not stipulated if your idea plugs into the *Low* input I'm not sure what it's supposed to achieve but here's a screen shot for comparison;
Yellow trace is Your circuit through *high input*.
Then Blue trace is Yours through *Low input*.

Mine is the Green trace (through the low input). Should be obvious which has the most bass roll off.

I doubt your circuit will have enough bass roll off to run flat out without issue.
Suck it and see but it never worked for me.

That resistor would need to be 5 Meg to get close to the same effect,, even then it still flattens out.

What the casual observer might miss,, or what even the experts tend to forget :shock:
Be very aware that both the magnetic PU's in your guitar and the input of the first triode stage work from
DC (Zero Hertz).
The design worked fine back in the 50's cause PU's where generally of much lower output.


Even a stock Strat at full Volume has massive low freq response (more than previous guitars from that era) and there is way to much low freq entering the Amplifier.
So obviously by rolling off the excessive low end *Right at the input* will go a long way to fixing the issues of splatter bass at high levels.

Phil.
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Post by DougH »

:mrgreen:

My "spice" circuit was just a joke. There was a thread on here a year or so ago about the "legendary spice" pedal, which was basically 2 jacks and a piece of cloth-covered wire between them. My rendition was just a parody using the typical jcm800 peaking-filter/interstage-divider. :mrgreen:

There's a lot to be said for paying attention to the input of an amp. On pedals, input coupling caps are usually carefully tuned according to the expected sound you want out of the pedal. On amps however, we've accepted the idea of DC coupling the inputs, amplifying everything down to DC just because that's the way it was done in the 50's. Guitar amps were designed with different goals in mind back then. I've added input caps to a few of my amps to eliminate scratchy guitar pots due to (apparently) leaky input tubes. In one case it kept me from getting shocked as a particular failure mode put high voltage dc on the input tube grid. There's nothing wrong with a little DC isolation... But this is definitely a potential tuning point for the amp as well. And I agree- many times the problems are due to too much gain.
"You have just tubescreamered or fuzzfaced yourself " -polarbearfx

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Post by DougH »

Hey Phil,

All I've gotta say is WOW!!!! It really works!! :applause: :applause: :applause: :applause:


I've got a Peavey Windsor that I modified into a JCM800. Currently I'm running it at 50W with 2 EL34's. Using the stock PV Windsor 4x12 with "Celestion-style" speakers. Nothing more anti-SRV/Fender/Texas/Americana than this setup (unless you used a real Marshall JCM800). I just stuck a cap and a couple jacks on a breadboard and plugged in my stock MIM strat. No "texas" pickups, no tube screamers blah blah, just straight into the amp. I went into the low gain input and ended up maxing the preamp and the master volume. Treble/mid at 50%, Bass at 75%. Voila! Instant SRV/Texas/whatever tone! Very clear and bell-like, with a hint of grit on the top. Turn the guitar vol to 7 or 8 and it is completely clean. But no matter what, you get sweet compression, sustain, feedback out of the power amp. 1.2nf-1.7nf sounds pretty good here. I'm going to install this in a guitar cord and mark it my "SRV" cord. :wink: BTW, I'm using the attenuator on an extreme setting to keep the volume manageable because this will get LOUD.

But this sounds really great- better than any "SRV sound" I've heard from any pedal or anything else. Thanks for the suggestion! :thumbsup :thumbsup
"You have just tubescreamered or fuzzfaced yourself " -polarbearfx

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Post by phatt »

Hi Doug,
That's Wonderful news!
Yep sounds like you've found the right value caps that nails the sweet spot of your Amp and speakers.

I just quitely mention it here and there as there is much less interest in *that tone* these days and I don't wish to bore the younger generation with old stuff.
Even so SRV tone is still often used as a tone reference point and this is just so darn simple yet insanely powerful.

One tone head bloke even abused me as a nutcase for making such a claim but hey I don't mind as he spent a fortune on Amps trying to nail that tone and I spent 60 cents on a few caps.

If I had money to bet, I'd lay a bet that the splitter box is likely still around and if opened you would find something similar inside it.

We will never be told but meantime we can now all have access to the same sound and not even have to open an amplifier. :lol:

This simple trick may well be one of the best kept secrets in guitarland :secret:
Cheers, Phil.

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Post by DougH »

I put the caps inside the plug of one of my cords. Now it is the "magic SRV cord". :wink:
"You have just tubescreamered or fuzzfaced yourself " -polarbearfx

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