Revoicing tone controls on an amp
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LesStrat
Reining PunLowered
Re: Revoicing tone controls on an amp
First, I would suggest you call Boogie (after all, you are nearby). My friend didn't like one of the channels on his Dual Rectalfire and called the company. They told him to ship it to them, and for a nominal fee (I think about $100), they factory modified the amp to his specs, keeping the warranty intact. Of course he had to ship it to them. But you are just down the freeway from them, aren't you?
First, I would suggest you call Boogie (after all, you are nearby). My friend didn't like one of the channels on his Dual Rectalfire and called the company. They told him to ship it to them, and for a nominal fee (I think about $100), they factory modified the amp to his specs, keeping the warranty intact. Of course he had to ship it to them. But you are just down the freeway from them, aren't you?
L
Lewguitar
Guest
Re: Revoicing tone controls on an amp
I dunno what's in your tone stack now, but I replace the .047 and .1 caps in the tone stack of all my blackface Fenders with a pair of .02 caps...as used in vintage '59 5F6-A tweed Bassman amps and Marshall Plexis.
Lew
I dunno what's in your tone stack now, but I replace the .047 and .1 caps in the tone stack of all my blackface Fenders with a pair of .02 caps...as used in vintage '59 5F6-A tweed Bassman amps and Marshall Plexis.
Lew
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some_dude
Raging BB Gunologist
Re: Revoicing tone controls on an amp
Pull out the 6L6 power tubes and install some EL34's.
Marshall tone is all about EL34s.
I really don't think making a change to the tone stack in the preamp will make it sound any more like a Marshall. It might sound like a Boogie with a different tone stack in it, but it wouldn't have that EL34 crunch.
Edit: Fixed spelling to make more sense.
Pull out the 6L6 power tubes and install some EL34's.
Marshall tone is all about EL34s.
I really don't think making a change to the tone stack in the preamp will make it sound any more like a Marshall. It might sound like a Boogie with a different tone stack in it, but it wouldn't have that EL34 crunch.
Edit: Fixed spelling to make more sense.
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L
Lewguitar
Guest
Re: Revoicing tone controls on an amp
The only Boogie I've ever owned was a Mark I with reverb but no graphic EQ. It did have the .047 & .1 tone stack. I sold it pretty quickly...my own modded Fenders were much more satisfying to me. Anyway, my experience with Mesa's and Boogies is limited.
However: changing the tone stack to a pair of .02 caps will make a significant diff in the tone compared to the stock values if they are currently .047 & .1. If your present treble cap is 250 pf, you might want to try 330 pf or 500 pf for more Marshall sizzle to the treble...if it's to much go back to 250pf.
Using a silver mica cap for the treble cap and a pair of Hovland Oil 'N Foil .02 caps for the bass and mid caps would sound totally state of the art! Sprague Orange Drops, Mallory 150's or Xicons would be just fine for the .02 too as long as they're rated at 400 volts or higher.
The midrange tone control should be changed to 25K if it is currently 10K.
The resulting tone will have a lot more bass...you'll probably find yourself turning the bass control down much further than before, like most of us do with our '59 tweed Bassman or vintage Marshall.
And the you'll have alot more mids...tho they'll have a nice lively "pluck" and more open voice than usual...like a Marshall.
What you won't be able to add much of is the Marshall crunch. You'll get a little more crunch but most of that Marshall crunch comes from a circuit I doubt your amp has: a cathode follower circuit.
Lew
The only Boogie I've ever owned was a Mark I with reverb but no graphic EQ. It did have the .047 & .1 tone stack. I sold it pretty quickly...my own modded Fenders were much more satisfying to me. Anyway, my experience with Mesa's and Boogies is limited.
However: changing the tone stack to a pair of .02 caps will make a significant diff in the tone compared to the stock values if they are currently .047 & .1. If your present treble cap is 250 pf, you might want to try 330 pf or 500 pf for more Marshall sizzle to the treble...if it's to much go back to 250pf.
Using a silver mica cap for the treble cap and a pair of Hovland Oil 'N Foil .02 caps for the bass and mid caps would sound totally state of the art! Sprague Orange Drops, Mallory 150's or Xicons would be just fine for the .02 too as long as they're rated at 400 volts or higher.
The midrange tone control should be changed to 25K if it is currently 10K.
The resulting tone will have a lot more bass...you'll probably find yourself turning the bass control down much further than before, like most of us do with our '59 tweed Bassman or vintage Marshall.
And the you'll have alot more mids...tho they'll have a nice lively "pluck" and more open voice than usual...like a Marshall.
What you won't be able to add much of is the Marshall crunch. You'll get a little more crunch but most of that Marshall crunch comes from a circuit I doubt your amp has: a cathode follower circuit.
Lew
rspst14
Tone Cat
Re: Revoicing tone controls on an amp
I'm not real familiar with Mesa amps, but I did something very similar to my Classic 50. I changed the value of the bass cap, replaced the mid and treble caps with higher quality ones, lowered the slope resistor value a little bit, and changed a couple cap values to smooth out the distortion channel a bit. It doesn't sound quite like a Marshall, but it did make a noticeable difference. If you're not familiar with working on amps, you might try taking it to the Mesa factory and letting them do the work. I agree though, you'll probably need EL34's if you want to get close to Marshall territory. One trick that might work for you is installing a pot that lets you adjust the value of the slope resistor. a 100k linear pot would work well for this...turn it up to shift the tone more towards the treble frequencies, turn it down to shift it more towards the bass frequencies. Common values are between 47k and 100k.
Ryan
I'm not real familiar with Mesa amps, but I did something very similar to my Classic 50. I changed the value of the bass cap, replaced the mid and treble caps with higher quality ones, lowered the slope resistor value a little bit, and changed a couple cap values to smooth out the distortion channel a bit. It doesn't sound quite like a Marshall, but it did make a noticeable difference. If you're not familiar with working on amps, you might try taking it to the Mesa factory and letting them do the work. I agree though, you'll probably need EL34's if you want to get close to Marshall territory. One trick that might work for you is installing a pot that lets you adjust the value of the slope resistor. a 100k linear pot would work well for this...turn it up to shift the tone more towards the treble frequencies, turn it down to shift it more towards the bass frequencies. Common values are between 47k and 100k.
Ryan
Re: Revoicing tone controls on an amp
Swing the slope resistor is a good trick indeed , Marshall did it on the 800's I believe, however you still would need to change out the cap values, and the pot values to mimic the tone stage of whatever amp you are looking into mimicing (the pot tapers also), bear in mind that the coupling caps that Marshall uses are generally smaller in capacitance than the Fender/Boogs, therefore those coupling stages tend to trim down the low end a bit, and keep things tight as the gain is increased. Also Marshall is famous for using a cathode following configuration at times (lower gain, more dirt), and that has it's own set of tonal propeties beside just distortion. A 10:1 swing on the slope resistor will give you and interesting, (with the original value somewhere in the middle) will give you an expanded palette; however revoicing the caps is the heart of the matter ... as swinging the slope will revoice it, but it also effects the cut/boost range of your controls.
rspst14 said:
Swing the slope resistor is a good trick indeed , Marshall did it on the 800's I believe, however you still would need to change out the cap values, and the pot values to mimic the tone stage of whatever amp you are looking into mimicing (the pot tapers also), bear in mind that the coupling caps that Marshall uses are generally smaller in capacitance than the Fender/Boogs, therefore those coupling stages tend to trim down the low end a bit, and keep things tight as the gain is increased. Also Marshall is famous for using a cathode following configuration at times (lower gain, more dirt), and that has it's own set of tonal propeties beside just distortion. A 10:1 swing on the slope resistor will give you and interesting, (with the original value somewhere in the middle) will give you an expanded palette; however revoicing the caps is the heart of the matter ... as swinging the slope will revoice it, but it also effects the cut/boost range of your controls.
Re: Revoicing tone controls on an amp
Another thing ... If you really want your tone stack to sound like the Marshalls, the impedance of that cathode follower design is lower than the Fender/Mesa anode (plate) follower (I guess they'd call that a common cathode), so that changes the frequency centers involved. If you revoiced the caps according to the higher source impedance that the tone stage sees (around 38k for Fenders and Boogs {although Mesa has different *newer*stuff} ), then you'll get the same frequency ranges involved, mimic the pot tapers and values, and you'll have the same throw range, and pot response.
Bear in mind that the mid controls on the FVM tone stacks just control the amount of mid cut, when you boost them as you say, you actually boost the bass and treble with them; You are reducing the overall insertion loss of the tone stage. Not saying it's a bad idea, just doesn't quite work the way people think it does.mrid said:
Another thing ... If you really want your tone stack to sound like the Marshalls, the impedance of that cathode follower design is lower than the Fender/Mesa anode (plate) follower (I guess they'd call that a common cathode), so that changes the frequency centers involved. If you revoiced the caps according to the higher source impedance that the tone stage sees (around 38k for Fenders and Boogs {although Mesa has different *newer*stuff} ), then you'll get the same frequency ranges involved, mimic the pot tapers and values, and you'll have the same throw range, and pot response.
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Re: Revoicing tone controls on an amp
Petaluma, CA is about 500 miles away from Orange County, CA
But there is a Boogie store (Like and actual Boogie store, not just a dealership) in Hollywood which is not far away.
Basically what I'd like to do is re-voice the EQ to what an old JCM800 would've used. I actually had some EL34s in the amp for a little bit but the cleans didn't sound as good and the amp became too middy. The amp seems to perform best with the 6L6's. However an EQ shift may change that.
LesStrat said:
Petaluma, CA is about 500 miles away from Orange County, CA
But there is a Boogie store (Like and actual Boogie store, not just a dealership) in Hollywood which is not far away.Basically what I'd like to do is re-voice the EQ to what an old JCM800 would've used. I actually had some EL34s in the amp for a little bit but the cleans didn't sound as good and the amp became too middy. The amp seems to perform best with the 6L6's. However an EQ shift may change that.
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