Tube Amp Archive

Thanks I'll check for the article. It does seem to get better as it gets louder and that goes along with what you and many others have said.

I'm going to try it at a gig tonight and see how it sounds.

Thank everyone for your knowledge and help. It's much appreciated!!

I hooked up the NF wire properly and the hum is gone.

The fuzz type tone is still there. When turn up the MV all the way and crank the amp to 5, it sounds great. When I turn the amp to 5 and bring up the MV it sounds like, well, poop.

Just noticed.... As it's wired now you have no negative feedback. The purple wire needs to go to the other side of the speaker jack. If the lugs were connected like the one I worked on it would make no difference..... Better pic attached... I wondered about that. Looking at the jack, the two sides ...

Is the shield from the shielded wires connected to the blue wire/left lugs on the pot? Probably is but can't tell for sure by the pic. Yes it is. Does it still hum when loaded in the head cab? I'll try it tonight Might try moving the LarMar wires around - raise them up as high and clear of other co...

Hi, I just installed a Larmar PPIMV in an older Germino Lead 55 and have a couple issues. There is a hum when the MV is all the way up. If I touch the chassis near the pot, the hum is reduced. The pot dual pot is right over the v3 PI socket (see pic). The potentially dumb question is, could this cau...

Thanks so much for all the responses!!! PS. it might save you from this horrible addiction called amp building once you smell the smoke your lost.<G> It's too late for that! Although my tech knowledge is too light for a build for sure. I'm comfortable with the relay setup and install to switch the p...

That is sound logic. So what might be the best way to disconnect the normal channel and leave the treble channel as is so I can free up the other volume pot to use as a switchable volume for the treble channel?

Or move the volume after the mixer with a coupler. Weird! You may as well go ahead and cascade it. You'll end up there anyhow. Everyone else did. :) As I understand it, cascading introduces a lot more gain and I really don't want to change the character of the amp that way. Just looking for a singl...

Thanks for the input. Both options sound a little confusing without something to look at.

Truthfully, I really like the bright channel and could probably do without the normal channel all together. Does that make it any easier/common? Or is this something that isn't done much?

Hi, I've got a 50 watt 4 hole clone that I'd like to mod in stages. First, I'd like to combine the normal and bright channel and control with a single vol instead of two. I'm probably searching wrong but I can't find any info on combining the channels. Later I'll be using the remaining volume for a ...

Hoffman has them, http://www.hoffmanamps.com/MyStore/perlshop.cgi?ACTION=thispage&thispage=parts20.htm&ORDER_ID=184988460 scoll down to see it. Check out the Mesa Boogie schematics, they use them a lot. Thanks Jana, I'll check it out. Can you open up your plexi and copy what was done there? The mod...

drz400 wrote: Switch both in and out and do it with Vactrols, it wont pop

Thanks!

What's a Vactrol?

Can you give me a PN and maybe a sketch of how it connects?

Thanks Jana! I still have more questions but I need to get info together first. I am still curious as to why you need to have a full zero volume to max volume with each 1 meg pot. I have a 100w Marshall Plexi that has this, two master volume mod, and I really like the way it works for live work. I h...

Thanks Jana! Will this work or do I need both 470k's?

Where do I put the 10 ohm resistor that skyboltone mentioned?

I went back and looked and these pots are after the tone stack. Is that going to make a difference in the switching?

Jana wrote:The thought just crossed my mind that these 1meg pots with the mix resistors might be in the pre-amp section. Is that where you are trying to do the switching?

Yes. These pots are the pre-amp section.

To clarify, this is a home built amp, not an actual marshall.

Thanks for the help!!!!!