Hi Myles. I'm brain-picking again. I've seen feedback circuits in a lot of amp schemos but this one, for an Ampeg V4, adds a .001 cap in parallel with the traditional limiting resistor. This is the only amp I've seen it on, and am wondering why Ampeg might have included it. Speculations appreciated. Thanks.



Best, Paul

Hi Myles,
I bought a Gibson GA-5, Les Paul Junior amp on closeout at MF. I love the way it sounds, but has a low level hum that is always present, but does not get louder with volume. Have you had any expierience with these guys? I've been a Valve Junior guy for a while and the head version is silent. The Gibson is not dark like the VJ and I really like the sound. Just wondering about that hum.
Thanks
Anthony

Thanks Myles, I'll start with the tube.
Anthony

Hi Myles,

I am looking into getting a little Fender Champ, If I wanted to run a US valve amp set for 110v in the UK at 240v, what would be the best thing to do? An external transformer or mod it, etc? Do you know if this changes the tone of the amp?

Thanks

Lee

Thanks for the info, Myles. I will look into the new reproductions, I had intially been looking for an old blackface champ, but they are hard to come by!

Myles, I had questions about Shuguang 12AX7 tubes in amps with DC heaters.

1) Do you know if there are any problems using the 8th & 9th Gen Shuguang 12ax7s in these type amps?

2) Do you know the current draw of the Shuguang 12ax7s (is it in the normal range for 12ax7s?).

Hi Myles,
I solved my GA-5 hum problem. I use a different outlet! Now it is almost dead silent. I'm going to connect an 8 ohm 12 inch cab to the little monster and was wondering what I will lose in sound quality going from the 4 ohm output to an 8 ohm cab. There is an 8 ohm wire coming from the transformer, but I'd rather not install an additional jack right now.
Thank You
Anthony

Thanks Myles. How about that 4 ohm output to the 8 ohm cab?
Thanks
Anthony

Thanks Myles.

Hi Myles,
Hoping you can help me.

I have a 1993 Marshall 1987x reissue that originally came with 5881 valves.
I'v been using a set of JJ e34L's for around a year now at the reccomendation of bob@eurotubes and its been great until recently when my amp went down while playing it cranked.

So I took it to a tech who says I shouldn't be using el34 types in my amp as it has different value screen resistors (among other things) to accomodate the 5881's and i was lucky my amp wasnt fried.

I emailed the Bob@eurotubes again who reassured me It should be fine with the e34l's. I trust bob's judgement generally but that sound control tech has me paranoid so I wanted to gather a third opinion.

Cheers,
Rich

Yeah the tech told me it had the marshall mods to run 5881's and that the e34l's i was using were going to be problematic.

I probably didnt give bob enough information when i discussed it with him. But I didnt want to harass the guy with emails about specifics i'd perhaps neglected. He's always been on the ball previously.

Can you reccomend me a set of valves to use in my situation?

Howdy Myles

This might already have been dealt with in this thread, but at 140-some-odd pages I'm going to take the lazy man's way out.

Over at the bass player side of this forum we're wrestling with the safety issues involved with low level amp repair, tube replacement, and the like. Some say that it's a job best left to The Tech's (more of these folks live across the pond in 240 volt land), others (like me) are DIY'ers to the bone. Can you refer us to a web page of safety tips that can remove some of the electrical Voo-Doo from the equation? Most of these issues appear to be involving electrical charges that is still stored in capacitors after the unit has been powered down.

Thanks!
Paul K

Thanks myles!
Sorry to keep bugging you but do you think i'd be able to use kt88's?

Looks like i'll go with the 6L6CHP's then!
Thanks myles.
I appreciate the advice.

Hi again Myles.

I have another question. I hope you dont mind.

So I got a set of matched JJ 6l6gc's. I looked around for the ones you mentioned but they were a fair bit more expensive than the JJ's so I just opted to go for them.

So they arrived this morning and after trying them out I'v noticed something...

Whenever I play a note at decent volume they give a high pitched rattle sound that sort of squeaks. The more I push the amp the worse it gets.
This only happens for a second as soon as the note is played but after all the trouble i'v been through with my amp its got me concerned.

I did wonder if it was perhaps that the valves were not broken in yet or perhaps i'v biased them too hot but I thought it best to ask a trusted opinion before i do anything else, just incase.

I am running the amp with an attenuator (tube cube) if that matters.

Thanks again!
Rich