Possible mods for Mk1 Boogie?

[mark]

I have recently been getting inside my Boogie (SOB loosely converted to a Mark 1 reissue.)

My amp does have many of Gil Arans mods, but that isn't quite the sound I'm after at the moment, and I'm wondering if anyone can recommend mods they have tried.

The sort of thing I'm wary of is how Mesa have increased the third stage grid leak resistor to 470K. If your amp doesn't have reverb like mine, the tone of the amp changes and the amp sounds very middle-y when it is turned up.

Anyway, I look forward to hearing from you.

Yours Sincerely

Mark Abbott

[ayan]

I
My amp does have many of Gil Arans mods, but that isn't quite the sound I'm after at the moment, and I'm wondering if anyone can recommend mods they have tried.

G'day, mate! Haven't changed my last name yet, Mark.... it's still Ayan.

Regarding the old Mk I mods, at that time I was heavily into the Boogie sound and tried to make the Mk IR sound more like a Boogie. Over the last maybe 6 or 7 years, or however long it's been since then, I've been more and more into "open sounding," as opposed to midrangey amps. I would probably approach moddying a Mark I differently at this point, but I sold mine back in Y2K and haven't felt the urge to get another one since then.

Cheers,

Gil

[mark]

Sorry about that chief!

Dear Gil

It has been some time since we've spoke and I couldn't remember whether it was an "r" or a "y". I spelt your name as I pronouce it, which is probably incorrect too, but to my own defence, I've yet to meet someone else with your surname. Yeah, I know I should get out more.

Gil, I pretty much wired my SOB as a reissue Mark 1 (minus reverb and the effects loop) with some of your mods incorporated. Stuff like the 1000pF on the input of input two didn't really work out for me. Though I did use the mods to the gain stage.

On the reissue amp there is a 470K grid leak resistor on the third stage in place of the 220K resistor that was there in previous circuits. As my amp doesn't have reverb, it did alter the sound a bit, but the full effect wasn't really noticeable until the amp was turned up. The effect was the treble seemed to compress and the mids were overpowering the tone of the amp in a really bad way.

One thing that I tried was putting 33K resistors in the grids of the first valve. It is one of those things that have been in and out of vogue. As we all know, at the time the Mark 1 was made by Randall Smith, he was into building a Fender amp with all the currents mods incorporated. Removing the grid stopper resistors was one of these mods.

As I previously mentioned in the past few years, having the grid stopper resistor attached to the pins on the valve has been in vogue, so I thought I'd give it a try. I haven't done any sort of a/b testing, but my initial thoughts were that input two sounded more Fender like and the glassy top end that had been present with my amp seemed to disappear. Which I wasn't too fond of, input one had a similar effect, but it worked for that channel.

I have found that I get quite a bit of noise when I'm using a guitar with a 500K volume pot into input two of my amp when it is dimed.
Using a guitar with a 250K and 100K pots offer less noise (hum) and when there is no lead plugged into the amp and it is on ten it is at it's noisiest.

I think this was one of the reasons that Randall Smith chose to use a 220K resistor across the input of the second stage.

Anyway, I could go on for a while over this circuit, these are some of the things that I am currently looking at with this amp.

Just out of curiousity Gil, what amp are you using these days?
I know you built a couple of beautiful Dumble clones sometime ago.

Good to talk with you again Gil.

Yours Sincerely

Mark Abbott

[ayan]

Dear Gil

It has been some time since we've spoke and I couldn't remember whether it was an "r" or a "y". I spelt your name as I pronouce it, which is probably incorrect too, but to my own defence, I've yet to meet someone else with your surname. Yeah, I know I should get out more.

Gil, I pretty much wired my SOB as a reissue Mark 1 (minus reverb and the effects loop) with some of your mods incorporated. Stuff like the 1000pF on the input of input two didn't really work out for me. Though I did use the mods to the gain stage.

On the reissue amp there is a 470K grid leak resistor on the third stage in place of the 220K resistor that was there in previous circuits. As my amp doesn't have reverb, it did alter the sound a bit, but the full effect wasn't really noticeable until the amp was turned up. The effect was the treble seemed to compress and the mids were overpowering the tone of the amp in a really bad way.

One thing that I tried was putting 33K resistors in the grids of the first valve. It is one of those things that have been in and out of vogue. As we all know, at the time the Mark 1 was made by Randall Smith, he was into building a Fender amp with all the currents mods incorporated. Removing the grid stopper resistors was one of these mods.

As I previously mentioned in the past few years, having the grid stopper resistor attached to the pins on the valve has been in vogue, so I thought I'd give it a try. I haven't done any sort of a/b testing, but my initial thoughts were that input two sounded more Fender like and the glassy top end that had been present with my amp seemed to disappear. Which I wasn't too fond of, input one had a similar effect, but it worked for that channel.

I have found that I get quite a bit of noise when I'm using a guitar with a 500K volume pot into input two of my amp when it is dimed.
Using a guitar with a 250K and 100K pots offer less noise (hum) and when there is no lead plugged into the amp and it is on ten it is at it's noisiest.

I think this was one of the reasons that Randall Smith chose to use a 220K resistor across the input of the second stage.

Anyway, I could go on for a while over this circuit, these are some of the things that I am currently looking at with this amp.

Just out of curiousity Gil, what amp are you using these days?
I know you built a couple of beautiful Dumble clones sometime ago.

Good to talk with you again Gil.

Yours Sincerely

Mark Abbott

Hi Mark,

Yes, long time no talk! As for my name, no worries I was joking, but if you want to know how it's pronounced most often, thing of the letters "A-N" and that's pretty much it.

In terms of amps, yes, I stuck to the D-clones I built over the years, and I ended building many of them. In the end, I kept two for myself and only very recently acquired a Music Man R-50, which is a small, portable amp w/rerverb that I like quite a bit. Now, I bought it as a "grab-n-go" amp and I hope it works well with a Zendrive pedal that I should be receiving pretty soon. I tried the Zendrive at NAMM earlier this year and like it a lot, so I thought I could have asimilar sound to that of my amps with the pedal and the little amp.

Nothing wrong with my amps, but they are bigger, require a rack for reverb/delay, so I thought I wouldn't mind having a little amp for some stuff -- as I get older, I am less and less fond of carrying too much around sometimes. The MM by itself has a great bluesy tone, BTW.

Anyway Mark, didn't mean to hijack your thread, but it's been great to have a chance to say hello again.

Cheers,

Gil

[BobW]

Any MM suggestions?

Hi Gil,

I like the compactness of the MM but found my RD-50 was too bright, no matter how it was set. I recently posted a mod, in the mods section, but was wondering if you may have comments or anything to add to my suggestions? BTW, I appreciate all of your input over at the "garage". thanks Bob

[ayan]

Hi Gil,

I like the compactness of the MM but found my RD-50 was too bright, no matter how it was set. I recently posted a mod, in the mods section, but was wondering if you may have comments or anything to add to my suggestions? BTW, I appreciate all of your input over at the "garage". thanks Bob

Hi Bob,

To be honest with you, I have not played with the MM too much. It is a bit on the bright side witht my Strat, for example, but that -- to me -- just means that I run the bass up at about 6 and the treble at about 3. I understand there are some cool mods for these amps, but mine is mint and I don't believe I will be attempting any mods on it. It's really just a grab-and-go amp for me, so it doesn't even have to sound "great." Just make some noise.

Cheers,

Gil

[BobW]

Hi Gil, I completely understand, your concerns about a mint RD-50. I also play a strat and found the middle/bridge and bridge PU positions to be too bright which is why I added the mod. Mine is in great condition too, and saved the original parts whenever/if I ever decide to sell it (doubt it) A great little amp that packs a punch. Thanks for the reply. :-)
Cheers
BobW

[Joe N]

Dear Gil

It has been some time since we've spoke and I couldn't remember whether it was an "r" or a "y". I spelt your name as I pronouce it, which is probably incorrect too, but to my own defence, I've yet to meet someone else with your surname. Yeah, I know I should get out more.

Gil, I pretty much wired my SOB as a reissue Mark 1 (minus reverb and the effects loop) with some of your mods incorporated. Stuff like the 1000pF on the input of input two didn't really work out for me. Though I did use the mods to the gain stage.

On the reissue amp there is a 470K grid leak resistor on the third stage in place of the 220K resistor that was there in previous circuits. As my amp doesn't have reverb, it did alter the sound a bit, but the full effect wasn't really noticeable until the amp was turned up. The effect was the treble seemed to compress and the mids were overpowering the tone of the amp in a really bad way.

One thing that I tried was putting 33K resistors in the grids of the first valve. It is one of those things that have been in and out of vogue. As we all know, at the time the Mark 1 was made by Randall Smith, he was into building a Fender amp with all the currents mods incorporated. Removing the grid stopper resistors was one of these mods.

As I previously mentioned in the past few years, having the grid stopper resistor attached to the pins on the valve has been in vogue, so I thought I'd give it a try. I haven't done any sort of a/b testing, but my initial thoughts were that input two sounded more Fender like and the glassy top end that had been present with my amp seemed to disappear. Which I wasn't too fond of, input one had a similar effect, but it worked for that channel.

I have found that I get quite a bit of noise when I'm using a guitar with a 500K volume pot into input two of my amp when it is dimed.
Using a guitar with a 250K and 100K pots offer less noise (hum) and when there is no lead plugged into the amp and it is on ten it is at it's noisiest.

I think this was one of the reasons that Randall Smith chose to use a 220K resistor across the input of the second stage.

Anyway, I could go on for a while over this circuit, these are some of the things that I am currently looking at with this amp.

Just out of curiousity Gil, what amp are you using these days?
I know you built a couple of beautiful Dumble clones sometime ago.

Good to talk with you again Gil.

Yours Sincerely

Mark Abbott

If you want to keep the gain that the 470K gives you, but like the tone of the 220K. you have to change that coupling cap before it from .047 to .022. you will then have the same cutoff freq. as before with the 220K grid leak. what are you trying to make it sound like? also putting in those grid stoppers really shouldn't do much to the tone as they are rolling off freq. that are way outside of the range that most guitar speakers reproduce. guitar speakers usually have a range between 75hz-6Khz, and a 68K grid stopper starts to roll off at 15Khz IIRC.
Joe N.