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

[YellowJacket]

Man, this thread is incredible; There's nothing like dispelling myths that have no business existing.
So, of COURSE it is the capacitor and potentiometer value affecting tone so drastically. When I changed the pots on my Les Paul to 500k pots, it drastically changed the tone of the guitar. I'm assuming the 300k tone pots were sucking out high end. Now, rolling back the tone pots leaves more midrange which gives a warm woody tone instead of a dull, sterile, and boomy one.
With an amplifier, it stands to reason that the gain pot, of all things, would have a HUGE impact on tone. So for my Rev F recto, I'd only have to swap out the gain pot for the red channel for Pre-500 tone? Mesa has stated that rectos are all capable of the same tones with different pot settings. Personally, I find turning up the mids (and presence) does a lot to tighten up the sound of my recto. It adds a lot of heaviness, cut, and aggression. This would explain why. I'd assume turning up the mids adds back at least a portion of the frequencies that the 1000k gain pot lets through.

Something else to think about. I have noticed that the Red channel on the Recto cannot be dialed back to provide a good clean tone, only the Orange channel can. I'm guessing something else in the Orange channel circuit contributes to the cleans as well as the pots. At any rate, it makes sense that Mesa chose the lower value gain pot allow for lower gain / rock tones. This makes for a more versatile amp, which is better for an amplifier company.

 

[clutch71]

The stock cap (.01uF) code reads SBE 715P (400V) 502K 9821
The new cap (.0047uF) reads SBE 715P (600V) 472J 1112

Thanks that makes sense. .0047 would allow less bass and low mids to pass.

Measuring the primary impedance should only be done by someone with the knowledge, skill, and experience to do it. Since that's not me, I wonder if any techs here have done it?

Anyone ever question why VIB is not present? Noticed that on Rev F-1F schem and the 3 channel I found.

So by the logic of what has been identified so far
1) A rev G can be modded to pre500 lore.
2) these points could be modded to switch between "Rev G" and "pre500" for those that like both....how cool is that?
3) Let's look @ the Single Rec, Rectoverb, and Mini Rect and see what those pots are and the value of the snubbing capacitor @ V2A.

Man...makes me want to pick up a Rev G!

 

[Third Age Amps]

I have a RevG for sale in the classifieds! I modified it in a different way but it's easy enough to perform "TheMagicEight Mod" to it.

 

[R_ADKINS80]

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?

 

[screamingdaisy]

Years ago pre500 lore was kept solely to the transformers. This post is the first I've seen that challenges that, and I've been around for a while. Everything I've read in the past is that the transformers for the early Duals were from the MarkIII's used until that supply. Once it ran out Mesa needed a replacment. I'll push it further with something I've never seen about the pre500 transformers....any one ever measured the primary impedance of a pre500 transformer? I'd like to see a comparison of the primary impedance of a pre500 vs a later model. If they are wound the same, in theory this might elimanates the transformer as the fabled back bone of the pre500 tone.

The Pre-500 transformer myth was disproved years ago. They kept using the Mark III transformers until somewhere around serial number 2200, which is in the Rev F series. People have compared two Rev Fs with different transformers and said they sounded pretty much the same.

I've owned a Rev G and was never happy with it. I had the peasure of playing many Rev C, D, and F and always liked them better than my G.

Yes, the pre 500s did use the earlier transformer. However, it has been confirmed that lo and behold, so did Rev. F, and so did early Rev. G. Perhaps they sound better - they certainly sound different - but this is not the only change between revisions, and I'll point to the "Rev. F" schematic floating around to demonstrate my point.

I have a RevG for sale in the classifieds! I modified it in a different way but it's easy enough to perform "TheMagicEight Mod" to it.

I think I like this name better than calling it a "Pre-500 mod". Unless we've determined that these two components are the only two that need to be changed to bring a Rev D through G back to Rev C specs?


On a side note, there used to be a member on here (forget his name, but he's the dude who kept buying and selling early Rectos to test all these myths out) and he claimed that you could make a Rev G sound like a Rev C by pretty much diming the presence knob. Any chance anyone can test this theory against an amp with the MagicEight mod?

 

[Anonymous]

On a side note, there used to be a member on here (forget his name, but he's the dude who kept buying and selling early Rectos to test all these myths out) and he claimed that you could make a Rev G sound like a Rev C by pretty much diming the presence knob. Any chance anyone can test this theory against an amp with the MagicEight mod?

Rev. C may have used a different resistor in conjunction with the presence knob, and this could contribute to additional brightness that Rev. C is known for vs. Rev. D. The ONLY knob that will change the feel of the preamp is the gain knob. Everything else shapes tone after distortion, and while it can still change the feel of the amp once the power section starts to breathe, your ears would have to be pretty bad to mistake a Rev. G for Rev. C.

 

[screamingdaisy]

Rev. C may have used a different resistor in conjunction with the presence knob, and this could contribute to additional brightness that Rev. C is known for vs. Rev. D. The ONLY knob that will change the feel of the preamp is the gain knob. Everything else shapes tone after distortion, and while it can still change the feel of the amp once the power section starts to breathe, your ears would have to be pretty bad to mistake a Rev. G for Rev. C.

Cool. Just wondering as I have a bright and tight early Rev F and a Roadster. I found I can make the Roadster sound pretty much identical to the Rev F with the FX loops bypassed and some adjusting of the bass and presence knobs.

What I haven't been able to do is get the Roadster to produce the elastic response of the Rev F has in the orange channel, nor can I get the Rev F to produce the "huge" sound of the Roadster.

 

[YellowJacket]

Rev. C may have used a different resistor in conjunction with the presence knob, and this could contribute to additional brightness that Rev. C is known for vs. Rev. D. The ONLY knob that will change the feel of the preamp is the gain knob. Everything else shapes tone after distortion, and while it can still change the feel of the amp once the power section starts to breathe, your ears would have to be pretty bad to mistake a Rev. G for Rev. C.

Cool. Just wondering as I have a bright and tight early Rev F and a Roadster. I found I can make the Roadster sound pretty much identical to the Rev F with the FX loops bypassed and some adjusting of the bass and presence knobs.

What I haven't been able to do is get the Roadster to produce the elastic response of the Rev F has in the orange channel, nor can I get the Rev F to produce the "huge" sound of the Roadster.

Interesting. I get a very aggressive tone with my Recto when I roll back the treble and turn up the mids and presence. The gain gets way more focused and the attack become urgent, tight, and aggressive. The amp begins to sag a lot less and track much faster.

 

[screamingdaisy]

The gain gets way more focused and the attack become urgent, tight, and aggressive. The amp begins to sag a lot less and track much faster.

That's how I'd describe it too.

 

[Anonymous]

The gain gets way more focused and the attack become urgent, tight, and aggressive. The amp begins to sag a lot less and track much faster.

That's how I'd describe it too.

Even at bedroom levels?

 

[YellowJacket]

The gain gets way more focused and the attack become urgent, tight, and aggressive. The amp begins to sag a lot less and track much faster.

That's how I'd describe it too.

Ya. Turning down the mids and presence begins to give those super scooped, wide, and saggy numetal tones. They're great tones but for people who complain rectos don't have enough gain, turn up the mids!! I find that I use the same EQ settings for whatever I'm doing on the Recto; simply rolling off the volume knob on my guitar gives me a nice thick soft clip crunch that is really musical and sounds great. It kinda bridges the territory between Vintage Hi on the Electra Dyne and my heavy tones on the Recto. Both these amps could definitely live together in the same rig!

 

[JCDenton6]

:lol: You can call it what you like, but it's correct! And this would be going to Rev. D, not C.

Rev. C may have used a different resistor in conjunction with the presence knob, and this could contribute to additional brightness that Rev. C is known for vs. Rev. D. The ONLY knob that will change the feel of the preamp is the gain knob. Everything else shapes tone after distortion, and while it can still change the feel of the amp once the power section starts to breathe, your ears would have to be pretty bad to mistake a Rev. G for Rev. C.

I might be thinking outside the box but I wonder if Rev C used a capacitor even lower than .0047uF :shock:
I noticed the difference in the amp after I was done with the mods (and even more so when I changed my V1 tube out)

I wonder what Silverwulf (that's the person you were referring to screamingdaisy) would think of this thread, and boogiebabies and Elpelotero as well.
I know they all have owned countless revisions of rectos and would want to know there thoughts on this mod and the clips we've put up.

 

[JCDenton6]

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 remember reading this earlier on in this thread.

Essentially, this cap is the difference between the two and (non reborn) 3 channel Rectifiers, although instead of 5nF as with the Rev. C and D, the 3 channel Rectifiers don't have anything. Personally, I prefer the 10nF cap with the stock gain pots.

It still might be possible but if it can be done, you would have to find out which capacitor on the 3 channel head limits the flow of high end into the gain stages.

 

[Elpelotero]

Kudos to all of you willing to keep digging into this pre500 stuff and taking these risks with your gear.

I did all the research I possibly could on this subject 4 years ago, and you guys have taken it a step further. I am very glad to see how much the general public has learned about these amps. So many myths have been stripped. It's plain to see even on ebay, where one can assume the average seller does not read the Boogie Board.

I hope one day one of you has enough smarts/education to decode these differences exactly. I know nothing about electronics, but from what it seems, you guys are getting close.


On another note, I still have the Dreamweaver files for the Boogie Archives, and own the domain name. If any of you know how to create/upload websites, etc., I'm all ears. It's obvious with this thread people are still interested in the history of these amps.

In regards to the clips, I've heard them several times and to be honest, I can't pick up the tonal differences. It's very hard to record these amps without professional expertise. I've tried recording mine with protools and quality mics but have gotten terrible results that sound nothing like the amp. I believe though that this mod does something to the amp's tone. I'm just not tech savvy enough to know if this is "the mod."

 

[Anonymous]

I might be thinking outside the box but I wonder if Rev C used a capacitor even lower than .0047uF :shock:
I noticed the difference in the amp after I was done with the mods (and even more so when I changed my V1 tube out)

That's an interesting thought! I actually did try no cap there, and really didn't like the results, but maybe a smaller one would do the trick. I'll have to try 33nF or even 22nF at some point. No cap there was too much though (with the 1M pots). The gain became shrill and VERY fizzy. It was tight, but more like a scraping kind of tight than something with depth; much closer to a cheap distortion pedal than nice tube saturation IMO.

I guess the reason I think it's more to do with the presence circuit is because I've heard over and over that D is just a darker version of C; that their character is the same, and that different presence settings get you the same thing.

 

[JCDenton6]

^ Thanks for chiming in though, it's because of this board and this awesome thread and I started to become further educated in amplifier electronics and further my quest for awesome tone.
I see what you mean about the presence being the difference with Rev C and D, I wish I could've had the chance to play on either of those so I could have more or less of an idea of the difference.

I'm all for reviving the boogie archives, I'm going to talk to a few friends who have developed websites and see what can be done.

 

[Elpelotero]

I live in Manhattan, NY and frequently travel to DC, Chicago, Philly, and Connecticut is a train ride away. If any of you have some modded amps, I'd love to come try one! My amps are in storage at home in Miami. I can't play them in my NY apartment.

 

[JCDenton6]

^ Sounds like a good deal. I always wanted to be a part of an ampfest in the past but was always stuck somewhere. If your ever in the Chicago area, feel free to PM me and we'll jam and grab a few brews 8)

 

[YellowJacket]

Wait, YOU'RE in chicago? I was there last summer to pick up my Electra Dyne!!!

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

 

[JCDenton6]

Wait, YOU'RE in chicago? I was there last summer to pick up my Electra Dyne!!!

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

Yep Think I missed the thread when you bought the ED from cradlefish and you were on a roadtrip to pick the amp up.