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

[LesPaul70]

Here you can find link to the clips:

http://www.tonefinder.com/index.php?section=user&value=shemham

Wow, that sounds good. Especially the 50W channel 2 Vintage sound, awesome tightness, it's pure hot-rodded Marshall from hell! :twisted: The 100W samples aren't bad either, just a little mushier.

The samples are pretty close to what my C sounds like, esp. the tightness of the 50W sample. The main audible difference I can discern is the different top-end character - the highs of your modded Rec sound more saturated, or somewhat "wetter" (for the lack of a better word). I guess the different transformer might play a role in this. But otherwise, it (again, especially the 50W sample) is very close. You can consider your mods a success - and I believe that the EL34s help also in the tightness department.

 

[Shemham]

Thanks for the comments.

Hi,
What does this do to the sound/feel of the amp?

I've done the 100 ohm resister jumpers, that made the amp more present.

Installing the 5M5ohm resistor parallel to the 680Kohm resistor equals to removing the 2M2ohm/82pf circuit and replacing the 680Kohm with a 470Kohm resistor except it does not influence Raw mode at all. 82pf cap is so small that it should be insignificant with the 0.0022uf cap there.

Tone/feel wise the change is quite subtle. I get more gain, with more mids and lows. In other words, it makes the tone a bit fuller and I find it useful for leads. It's still something pretty minor. If you have changed the gain pot value, that will yield much bigger change and makes the change even less noticable. I didn't like the higher value gain pot and deciced to stick with standard Rev C/D specs.

Alternative method is to change the 2M2ohm resistor with a 1M5ohm which will give same resistance as Rev C/D in Vintage and Modern modes while adding more gain to Raw mode.

Wow, that sounds good. Especially the 50W channel 2 Vintage sound, awesome tightness, it's pure hot-rodded Marshall from hell! :twisted: The 100W samples aren't bad either, just a little mushier.

The samples are pretty close to what my C sounds like, esp. the tightness of the 50W sample. The main audible difference I can discern is the different top-end character - the highs of your modded Rec sound more saturated, or somewhat "wetter" (for the lack of a better word). I guess the different transformer might play a role in this. But otherwise, it (again, especially the 50W sample) is very close. You can consider your mods a success - and I believe that the EL34s help also in the tightness department.

Haha! Thanks. Yeah, it's kinda Marshallesque. It's what I use for both my rhythm and leads normally.

I actually tried 250kohm presence pot with Modern mode once. It (at least seemingly) tightened the lowend even further as you're likely to dial your presence higher, but that was way overkill and made the mode a bit too brittle IMO. But yeah, some of the differences with the highs might be related to different output transformer, although you already confirmed that Rev G does not sound like Rev F through Rev C's power section so there's likely something else going on with Rev F's preamp.

 

[JCDenton6]

I finally got around to make some clips of my modified Multi-Watt DR.

nearly two years ago I made the following changes: 1) jumped the 100 ohm resistors 2) added 5M5ohm Resistor in parallel to the 680k resistor in the first filter section to drop the total resistance to Rev C/D values.

Here you can find link to the clips:

http://www.tonefinder.com/index.php?section=user&value=shemham

I cannot believe I was such a slacker I never got around to uploading a recording.

This is a scratch track I made for my drummer to lay his tracks down to. Forgive the beep as It is hard coded in the mp3 for him.

https://soundcloud.com/lasanche/hell-correct

That sounds really good guys!

These clips are pretty much nailing the tone on Rev C clip:

https://dl.dropboxusercontent.com/u/47381724/PRE500-6L6.mp3

 

[user 38435]

That sounds really good guys!

These clips are pretty much nailing the tone on Rev C clip:

https://dl.dropboxusercontent.com/u/47381724/PRE500-6L6.mp3

wow - awesome tone.
what amp version do you use, and what mods have you done?
as far as I have read here in this board, you have tried some different mods. so - which mods are responsible for this tone?

 

[JCDenton6]

Thanks, I'll PM the mods to you.

 

[JCDenton6]

I found more anomalies that I have previously overlooked: R503(?) and R361-R362(100 ohm) , which I didn't find on the schematics and is soldered in Rev C, D, E, F and up into the early serials of Rev G.

I didn't see this on later Rev G's...

Might have to download for full size pics.

Rev C: https://www.dropbox.com/s/hglqdm9uiiek2qv/IMG_5324.jpg?dl=0
https://www.dropbox.com/s/1eglwvt1py492dz/IMG_5344.jpg?dl=0

Early Rev G: https://www.dropbox.com/s/yr7ozypwv6bdvry/revg3.jpg?dl=0

My Rev G Triple without R503 and R361-R362: https://www.dropbox.com/s/ixsx9v8x9xefquq/SDC10123.JPG?dl=0
https://www.dropbox.com/s/z12xmcnqe8ddnzg/SDC10127.JPG?dl=0

EDIT: Finally found the full 2 ch schematic, So apparently R503 is a 220 ohm 5w wire round resistor that was used in the LDR power supply in early models.
R361-R362: They were used to reduce hum when the tap off of the PT was soldered in a different place in the older amps, the Rev G's setup like mine have a tap running of the PT and is soldered right before the LDR power supply, nothing to do with tonality.

 

[mat.corona]

I've revamped the Lasse & Mago DI after the pre 500 mod. Sounds Huge in my opinion. What do you think? https://www.youtube.com/watch?v=yi7Gwa7PosA

 

[JCDenton6]

It sounds great, you can hear the characteristics of the pre 500 rectos in the clip.

 

[Shemham]

Yeah, that does sound huge no question. I'd still like to hear the amp without the OD-808 slamming the front end.

 

[wolf]

hey guys...I just recorded another short clip of my modded recto...

https://soundcloud.com/wolfernus/sd-livewire-metal-mesa-dual-recto-test

 

[JCDenton6]

Nice!

 

[afu]

hey guys...I just recorded another short clip of my modded recto...

https://soundcloud.com/wolfernus/sd-livewire-metal-mesa-dual-recto-test

That's SICK!!!! Nice.

 

[HughMan]

Hi everyone,

my apologies for resurrecting an old thread, but could anyone please help me in obtaining the Rev C schematic mentioned in:

http://forum.grailtone.com/viewtopic.php?f=24&t=58838&start=120

The link mentioned on that page appears to be no longer available (https://docs.google.com/open?id=0B3ypbi1bfywVYjEwc2VRWHdMek0).
I was wondering if anyone still has it and could PM me the details to obtain it?

Many Thanks in advance.

Cheers,
Hugh.

 

[JCDenton6]

Here you go

https://drive.google.com/open?id=1WgRRHrsXM9ekmQ-oXbAQtt_X5jNUQuxY

 

[HughMan]

Here you go

https://drive.google.com/open?id=1WgRRHrsXM9ekmQ-oXbAQtt_X5jNUQuxY

Fantastic! Thank you very much for this.
Very interesting to see that the V1 tube is completely switched out of the circuit (via LDRs) for the Orange clean setting, in this revision.

I have a Rev D which is obviously much closer to the Rev C than the Rev F (for which the most common schematic is floating on the net).
My guess is that the changes from Rev C to Rev D are minimal.

Cheers,
Hugh.

 

[Shemham]

I have a Rev D which is obviously much closer to the Rev C than the Rev F (for which the most common schematic is floating on the net).
My guess is that the changes from Rev C to Rev D are minimal.

Cheers,
Hugh.

I think you're right that the Rev C and D circuits are nearly identical. Many have reported that Rev D is slightly darker compared to Rev C. You could measure the resistance of the presence pot on the Red channel to see if it's 220k or 100k ohms. This could be one possible difference between the two. Another forum member also claimed that the loop on Rev C does not function properly as Mesa had accidentally drawn the PCB with reverse polarity for the loop bypass relay coils.

 

[HughMan]

I think you're right that the Rev C and D circuits are nearly identical. Many have reported that Rev D is slightly darker compared to Rev C. You could measure the resistance of the presence pot on the Red channel to see if it's 220k or 100k ohms. This could be one possible difference between the two. Another forum member also claimed that the loop on Rev C does not function properly as Mesa had accidentally drawn the PCB with reverse polarity for the loop bypass relay coils.

I just took a look inside the chassis and upon measurement, I can confirm that the presence pot values on a Rev D Dual Recto are:
Orange Channel: 22K
Red Channel: 220K

i.e., as per the RevC schematic supplied.

However, my curiosity got the better of me this time and since I was always puzzled as to what a certain bit of "goop" was for, I removed said "goop" and saw the following:

https://ibb.co/kjhxEx

My apologies if this has been discussed before and is common knowledge, but what on earth is going on here? There's a bit of wire (thick, single conductor) from pin 9 of the V2 preamp tube (heater centre tap), that is just floating (i.e., not soldered anywhere else) and I'm not seeing this anywhere else in the preamp section. It is close to a resistor (the 475K V2A input grid resistor on the LDR side not the tube side), but not touching it, and a bit of "goop" was used to secure it there and I gather to prevent it from touching the resistor.

Does anyone know why this is there? It is rather strange.

Thank you .

Cheers,
Hugh.

 

[APEMAN]

-

 

[JCDenton6]

I could've sworn that wire was there to reduce microphonics and other noise from V3 in the earlier Rectos IIRC :|

 

[HughMan]

Does anyone know why this is there? It is rather strange.

... yes it is, could be a previous owner cut out a cap???

Yeah, my initial reaction was also that someone had soldered a wire in the wrong place (this is the centre tap of the heater after all) and then just cut it. But, (a) they could have cut it shorter and (b) the non-soldered end was fixed in place with neutral cure (I hope) silicone rubber (you can still see traces of that, I haven't removed all of it).

So it looks kinda intentional, but the fact that one end is floating has me puzzled.