Want Pre500 tone? Here's how to get it!

[Anonymous]

Magic Eight, you mean to say that one capacitor is the difference between tube tone and a Metal Zone pedal? :lol:

:lol: Maybe I exaggerated.

 

[clutch71]

The Pre-500 transformer myth was disproved years ago...

I'm not sure it has been disproved other than the fact that the Mark III transformers run well past the 500's into the 2200's. The primary impedance of a transformer would effect tone. I had a VTM 60 that I modded from 6L6 to EL34 but did not replace the stock OT. The mids had a rather diff quality (best description would be honky), but wasn't quite what I wanted. As an X Dual Rec user and abuser the experience was nothing like swapping El34 for 6L6 in a DR. Recently I wired in a Dagnal out of my DSL 50 into the VTM. The primary has to be right around 3.6 K. Problem solved. I believe the primary impedance of the VTM 60 transformer to be right around 4.5K, it is still used in 6505 combo to this day....same manufacturer and model #. My source for that measurement is the internet so take that for what it's worth.

Typically the winding for 6L6 is diff than for EL34. Make no mistake....I'm not trying to argue here. My electronics knowledge is relatively limited. I'm pretty confident that in order to disprove the myth of the Mark III transformers we would need to see a comparison of the primary impedance vs. the transformers that were later used. Odds are it is going to be close.

There is also a possibility that materials could be different. Those that sell transforemers will also tell you that matters.

 

[clutch71]

Liking what I am hearing here! Does anyone know if changing out the gain pot on a 3ch for a higher value would have a similar tone/gain improvement?

I'd have to say yes in theory if the gain post are 250k and if the snubbing capacitor @ V2A is .01. That's also why I'm curious on the Single Recs and the Mini which claims to be tighter BTW.

I would love to have access to a C, D, E, F, and G. The archetecture should be relatively similar. I could then trace out a schematic for each based on F-1F that's out there. It looks pretty authentic but who knows.....Differences could then be properly documented. I think Mikey83 is in Ohio but I don't remember what version he has.

Unfortunately JCDenton, Screaming Daisy's, the MagicEight, YellowJacket and I are no where near each other. I travel a lot but you guys are no where near where I go EL Pelotero and I have shared many a beer in Gainesville back in the day. His C was my favorite Recto of all time.

 

[Third Age Amps]

http://www.pedalpartsplus.com/mm5/m...ode=PPP&Product_Code=7515&Category_Code=Pot16

This place sells the 16mm 1M and 500k Audio pots for just over $1!

 

[screamingdaisy]

The Pre-500 transformer myth was disproved years ago...

I'm not sure it has been disproved other than the fact that the Mark III transformers run well past the 500's into the 2200's.

Which disproves the myth.

The original myth was that the Pre-500s sounded better, and part of the myth included that the reason was because they used leftover Mark III transformers in them with the assumption that after the first 500 they started using a different transformer. Once it was discovered that post 500 Rectos had them too it became the Pre-1000... then the Pre-2000... and now that people know that Rev C through F all contained leftover Mark III transformers it's become accepted that the Rev C sound wasn't due to it being loaded with "magic" transformers.

 

[YellowJacket]

Yes exactly. Guitarists like to believe that sprinkling holy water on their amps will magically make them better. It stands to reason that a GAIN POT and an associated cap would have a drastic effect on tone considering the importance of gain on the signal chain. Sure, there may be a few other subtle differences such as presence pot values and maybe another capacitor / resistor or two, but the preamp circuit has to be the most important part of the amp with a high gain head.

 

[screamingdaisy]

Yes exactly. Guitarists like to believe that sprinkling holy water on their amps will magically make them better.

The other thing to factor in is the exclusiveness that the original myth provided. Magic out of production transformers made the Rev C sound seem more unobtainable, and therefore desirable. Boiling the sonic change down to a simple pot and cap swap makes the amp seem much more mundane.

 

[JCDenton6]

Anyone else try this yet? And do you guys think this should be stickied?

 

[YellowJacket]

I hate to be a party pooper but I'm rather happy with my Rev F as is. It definitely has more than enough bite and gain for me. Turning up the mids and presence turns it into a metal monster!

Yes, this should be stickied!

 

[JCDenton6]

Hey R_ADKINS80, check this out. IT can be done on a 3 Ch head, thanks to TheMagicEight!
From another thread:

I would seriously suggest modding it. Change the red gain pot to 1M and add a 5nF (500+V) cap going from the D power rail to ground, and you'll have one hell of a low volume tone! Should only take a couple of mins to do, it's totally reversible, and the sound and the feel of the amp at low volumes will be fantastic. Should get close to Pre-500 tone, though I haven't yet tried this with a 3-channel.

This should help in response to your question earlier on in the thread. IF you do it, let us know how it turns out

 

[R_ADKINS80]

any clue where said capacitor is located?

 

[Anonymous]

any clue where said capacitor is located?

Nowhere on the 3-channel, so you'll just add one wherever is convenient.

 

[R_ADKINS80]

Ok, so what is the "D power rail"?

 

[kramerxxx]

One Question:

If this adds more High-Mids back in, how can I do this to my 3-Channel Dual Rec?

If I could remove some of the bass and have less of a 'scooped' mids sound, this would be my ideal amp.

thx,
Steve

 

[Anonymous]

One Question:

If this adds more High-Mids back in, how can I do this to my 3-Channel Dual Rec?

If I could remove some of the bass and have less of a 'scooped' mids sound, this would be my ideal amp.

thx,
Steve

Sounds like this would probably do the trick! The first thing to do is to change the Red gain pot to 1M audio. Transfer the cap that is on the old gain pot to the new one.

Next, get the same cap I mentioned earlier (5nF, at least 450V). Now find the D power rail. V2 pins 1 and 6 each connect to 100k resistors, and on the other side of those resistors is the D power rail. Somewhere on this rail, you'll need to connect the capacitor to ground. I'm not sure where because I haven't worked on a 3-channel amp, but I'd bet there's a spot on this rail that's physically close to a ground.

 

[Anonymous]

If anyone with a 3-channel Rectifier or otherwise is near the NW corner of CT and would like help trying this, shoot me a PM and we can meet up sometime. This way, I could take pictures and write out very easy to follow directions.

 

[R_ADKINS80]

just for reference....I have had my 3ch out of the shell many times.....there are no capacitors on ANY of the front panel pots what so ever. if there is a gain pot capacitor then it is on the pcb where the leads go or somewhere.

 

[Anonymous]

just for reference....I have had my 3ch out of the shell many times.....there are no capacitors on ANY of the front panel pots what so ever. if there is a gain pot capacitor then it is on the pcb where the leads go or somewhere.

Cool! You'd just have to change the pot then (assuming the amp matches the schematic floating around).

 

[JCDenton6]

Got a few pics of my old 3CH dual, hope this can be used for reference.

 

[Third Age Amps]

Just changed the GAIN pot on my Two-Channel to the 1M and WHAT A DIFFERENCE! Same as what has been posted before. I doubt you would notice much of a tonal difference on a recording, but in the room it has become concussive. Not flabby, mushy bass overwhelming the other tones, just much more movement of the speakers. And that is a MAJOR factor in improving recorded tone. Speaker excursion contributes to the richness and warmth of your tone more than you would think.

Read Slipperman's ramblings and you'll learn a TON about recording distorted guitars.

It's all here:

http://www.badmuckingfastard.com/sound/slipperman.html

Anyway, Three cheers for TheMagicEight's hard work at deciphering a great tone mod!

:mrgreen: