finally got my tube amp kit up and running!

[muttonchopsrule]

i bought a p1 extreme kit from AX84.com back in november, and just got the thing working now. whenever i powered it up, i would get sound (not good sound though, it was just barely passing any signal), but the volume and gain controls didn't function at all, and there was still sound coming from the speaker when the master volume was turned all the way down.

since november, i thought i must have had something wired wrong, and tore the thing apart and rebuilt it from the ground up TWICE, and it still did the exact same thing. i became discouraged and it ended up sitting on top of my dresser until last week. i decided to troubleshoot it further, and came to realize that the volume and gain pots weren't functioning as they should. so i got new ones, and a problem that ended up taking me that long to realize took less than 5 minutes to actually fix :smack:

but it sounds pretty killer. since i got it working properly i've added an additional gain stage. it has enough gain to keep up with a marshall or a mesa or anything really, and the tone ain't too shabby! it sounds pretty killer through the marshall 4x12, especially when it's dimed. and it's a pretty loud 7 (or so) watts!

here's a couple pics:

the pics are a little outdated, as it now has another 12AX7 in the empty slot. but that's the jist of it.

i want to build a channel-switcher now

 

[stevie_bees]

Re: finally got my tube amp kit up and running!

Cool. I'd like to give something like that a go. Something else to add to the list of things to do. Congrats.

 

[muttonchopsrule]

Re: finally got my tube amp kit up and running!

Cool. I'd like to give something like that a go. Something else to add to the list of things to do. Congrats.

thanks man. i definitely recommend it. as long as you're good with a soldering iron and can follow a schematic, you should have no problem being successful with it...provided that none of the components in the kit are defective . i think there's a possibility that those volume and gain pots were bad out of the box, although there is a chance that i toasted them with the soldering iron. they did send me a wrong resistor too, which isn't a hige deal, but i like saying that the reason the amp didn't work at first was due to the pots being defective, that way i'm not to blame

building your own amp is for sure a fun and rewarding experience though.

 

[stevie_bees]

Re: finally got my tube amp kit up and running!

thanks man. i definitely recommend it. as long as you're good with a soldering iron and can follow a schematic, you should have no problem being successful with it...provided that none of the components in the kit are defective . i think there's a possibility that those volume and gain pots were bad out of the box, although there is a chance that i toasted them with the soldering iron. they did send me a wrong resistor too, which isn't a hige deal, but i like saying that the reason the amp didn't work at first was due to the pots being defective, that way i'm not to blame

building your own amp is for sure a fun and rewarding experience though.

I'm an electronics tech in the RAF, so I have got a soldering iron attachment that I can swap for my hand! Glad you were able to find the problem, it can get REALLY frustrating sometimes.

 

[More-Gear-Than-Skill]

Re: finally got my tube amp kit up and running!

Well done man! Strange enough, i had the exact problem with my P1. I eventually made a little "probe" out of a headphone, coming out of an old tapedeck, which alowed me to "inject" a signal. I traced the problem to a cooked volume pot also. After 2 rebuilds, and frustration! I built from scratch, using an old gorrilla chassis.

For those interested, below is an sound example of how sweet this little thing is. I plugged straight in, with a tele, and recorded a 1x12 cab with a joe meek mic. The guitar volume is the distor controller. Oh, and i opted for the EL84 power valve...

And it's loud man! I'm still surprised how cool it sounds, for such a simple thing.

Listen... . . .
http://s23.photobucket.com/albums/b366/moregear/?action=view&current=P1Noodles.flv

see guts

 

[stevie_bees]

Re: finally got my tube amp kit up and running!

Very cool tones.

 

[muttonchopsrule]

Re: finally got my tube amp kit up and running!

Well done man! Strange enough, i had the exact problem with my P1. I eventually made a little "probe" out of a headphone, coming out of an old tapedeck, which alowed me to "inject" a signal. I traced the problem to a cooked volume pot also. After 2 rebuilds, and frustration! I built from scratch, using an old gorrilla chassis.

For those interested, below is an sound example of how sweet this little thing is. I plugged straight in, with a tele, and recorded a 1x12 cab with a joe meek mic. The guitar volume is the distor controller. Oh, and i opted for the EL84 power valve...

And it's loud man! I'm still surprised how cool it sounds, for such a simple thing.

Listen... . . .
http://s23.photobucket.com/albums/b366/moregear/?action=view&current=P1Noodles.flv

see guts

good stuff man! the clip sounds great.
so you got bats pots too, eh? what a pain in the arse!!!

 

[MattPete]

Re: finally got my tube amp kit up and running!

I added a second channel to mine. The first channel is stock. A footswitch routes (Weber relay) routes the output from the 1st stage to either the stock 2nd stage or the second channel. The second channel consists of two stages, both with 800k cathode resistors and .68u bypass caps.

I had to add a 200k/200k voltage divider between stages 2 and 3, otherwise the 2nd stage would blast the 3rd stage into oblivion. I also had a bit of parasitic oscillation, so I jumpered a 100pf cap from the anode/plate of the 3rd stage to it's grid.

I also added a switchable tone stack that goes from the stock 500pf treble 100k slope resistor, to 350pf/56k and 250pf/33k. I got the idea from here (but I used a 3-way switch).

I also added a Hammond steel chassis cover.

Overall, it's a killer little amp.

 

[More-Gear-Than-Skill]

Re: finally got my tube amp kit up and running!

MattPete, that is some serious mod activity! To be honest, i did mine as a bit of a colour by numbers thing, and then when searching for the fault, i grew to understand the tube functions more...

As for the bad pots, yeah... but i am guessing it was cooked by me and my hot solder. I bought all my bits from the general electronics store here in town. Except the iron, the output is the hammond prescribed one, and the PT is a lucky find/butcher, from a military radar thingie...