Best Master Volume Mod for a JCM800???

[AmpliFIRE]

Ok, here's the deal. I absolutely love my stock JCM800 2204 with a pedal. but I need to tame the volume. What is the best master volume mod that still retains the tone of the amp at lower levels? I don't think I want an attenuator hot plate as I've been down that road a few times.

Also, I really want something that can be cleanly reversed if I don't like it...

 

[PlinytheWelder]

The Metroamp Lar/Mar PPIMV. http://metroamp.com/store/index.php?main_page=product_info&cPath=78&products_id=498
I have one in my Laney GH-100L and my Express clone and it's the best MV out there IMO.
There's an 80 page thread on it here... http://forum.metroamp.com/viewtopic.php?f=4&t=4390

 

[JerryP]

Nothing. I used a PPIV master in my 2204 for years and I remember how much better it sounded once I took it out. Just my opinion based on experience

+1
I hate PPIMV's in higher gain amps. If you need more control than you get with the stock master a HotPlate is your best option IMO.
Jerry

 

[ke2]

Hey, Paige! I thought the 2204 had a master?

Or are you thinking about a 2nd one that`ll work as a hot plate?

A very good friend of mine has a 50 watt 800, and I`ve tried it out with my ESP with emgs and a ts-9.

I could go from guns n roses clean to master of puppets, just with the pickup switch and the tube screamer.

It`s a great amp, have you tried boosting it?

 

[Nico]

Nothing. I used a PPIV master in my 2204 for years and I remember how much better it sounded once I took it out. Just my opinion based on experience

+1
I hate PPIMV's in higher gain amps. If you need more control than you get with the stock master a HotPlate is your best option IMO.
Jerry

I modded my JCM 800 with a PPIMV and I hated it after that, it won't give you the sounds you want because you wont have power amp distorsion. Just get an attenuator...

 

[jlbaxe]

I use a THD hot plate but I have to tweak both the THD and JMP100 to find the sweet spot. It doesnt sound right to me when I crank the amp and adjust the hotplate to the desired volume. I have to find the right balance, Same when I use it with my Mesa MKIII.

 

[yngzaklynch]

I'm with Jerry on this one. My Vintage Modern has a PPIMV but I wonder if a really good attenuator isn't the best bet.

 

[PlinytheWelder]

With respect, all I can say is that all PPIMV's are not alike...

 

[Vrad]

I'm with Dave on this. I converted my super lead to a 2203 and it has a regular pre mv and it sounds better to me than it did with a post pi mv.

 

[JerryP]

With respect, all I can say is that all PPIMV's are not alike...

Not all the same, but the results are very similar. No matter which one you use it still drives the PI harder and give you the sound I don't like.

My way of using a HotPlate is to get the amp set to a tone you like and then use the HP to knock the volume down only as needed. I don't use the HP to allow me to crank the amp louder. That method works with a low gain amp like a plexi that needs the power section to distort.
Jerry

 

[paolojm]

Inserting a 120k resistor between the existing MV wiper and PI coupling cap maintains the low end response at low volumes.
The preamp can easily be modded for a touch more gain.
Together this = win.

 

[duesentrieb]

a) add a 470k between the treble (middle) and the master. this will give you better control over the tonestack and decrease the volume. Sounds fatter too.

b) add a 220k after the master (middle) to the PI (as already said), but keep in mind that this is also a bit like an antenna and the master set to 0 may cause still some signal to come though. Solder the 220k to the PI's 22nF - and NOT to the master vol.

c) if thats still not enough, locate the 470R at the PI's tail. Increase its value (step by step) - even up to several k-Ohms (the 2205 uses 10k here if I remember correctly). Drops volume a lot.

 

[jabberwocker]

a) add a 470k between the treble (middle) and the master. this will give you better control over the tonestack and decrease the volume. Sounds fatter too.

b) add a 220k after the master (middle) to the PI (as already said), but keep in mind that this is also a bit like an antenna and the master set to 0 may cause still some signal to come though. Solder the 220k to the PI's 22nF - and NOT to the master vol.

c) if thats still not enough, locate the 470R at the PI's tail. Increase its value (step by step) - even up to several k-Ohms (the 2205 uses 10k here if I remember correctly). Drops volume a lot.

I'd like to thank you for that tip in A . That 470k resistor really makes a difference. Didn't try the other ones on the list as the MV works great already. I just installed it in a '68 marshall PA that I first restored but then hacked up with four of the inputs converted to bass spec, and with the extra inputs cascaded. Lotsa fun