Amp Tech Thread / Ask a tech Q

[Wesogkan]

Oi...trying to narrow down the best preamp to copy (will be used with a Sunn 2000s AND/OR an Ampeg V4 that will have plug ins for it). Either a Matamp or Orange gain...donno what sounds best circuit-wise.

[Hemisaurus]

That's kind of like asking someone what your favourite flavour of ice cream should be, I'm out 

[hayseed]

Sunn Cab is rewired and happy for now. Fender Cab is as dead it can get....time to walk away for a bit!

[Wesogkan]

That's kind of like asking someone what your favourite flavour of ice cream should be, I'm out 

I know...arghhhh.

[hayseed]

who does cheap  re cones or is it cheaper to re cone my 15's myself? OR is it cheaper to just buy new speakers?

I am researching this stuff right now. Seems like re cones go about $75 -90 by someone else or $60- 75 for a kit. Not sure if i am checking the correct places.

I did find Eminence Alpha 15A's for $57.99. I realize they are not the best speaker BUT are they worth it to buy them instead of repairing what i have?

[Hemisaurus]

Since I've never found a source for generic cones and voice coils on this continent, I've found unless it's some kind of special vintage speaker, or a really high powered woofer, it's cheaper to replace.

You can always keep the old ones, and recone them at a later date.

Yeah, I have a stack of speakers to recone, if I ever find a source of nice cheap generic parts

[VOLVO)))]

I use the Eminence Delta 15Bs in my bass cab, and they're fucking quality. I don't care what people say. They have survived two-ish years of being SLAMMED with square waves.

[TheWolf IsLoose]

I just got 2 Eminence CA 154 15" speakers for an old gutted Ampeg B25-B cab $50.99/ea. Not sure how they sound yet, one of them arrived with about 1" of the foam glued on wrong where it meets the speaker rim, had to send it back. Waiting for replacement...*sigh*

[Hemisaurus]

Seeing as we're talking speakers, has anyone tried the Carvin Neo's?

I was thinking about redoing my 4x10 with them, back when I was using it for gigging, they have 12, 15 and 18"s in the Neodyium as well, very reasonable, like Carvin usually is, they're standard drivers are pretty bulletproof.

[hayseed]

I'm not sure what i am gonna do with my speaker problem yet. I may just try to sell the blown stuff to a local guy and sell the Bassman cab for WAY less than what i bought it for. I am gonna clean up my Sunn 2x15 and sell it as well i think. I just bought a Peavey 1510 T-Fest and i am picking it up this weekend. Very cool cabinet- 2x15, 2x10 and 3 tweeters! Can't find any info on the thing on the internet at all but it just so damn cool!

OR... i may try a re-cone on some of the speakers just to learn how to do it for myself. Why not? Plus i feel a little guilty for trashing 2 perfectly good SRO's that sounded fine where they were in the first place.

[Hemisaurus]

The why not might be that an EV recone kit, the cheapest I can find is $60, well on eBay there's one for $40 + $10 shipping.

You might be able to piece something together cheaper from Mat Electronics they now seem to be carrying a generic 2" voice coil, so maybe there's hope for my broken speaker stack yet.

Ah bollocks, no, I need a 2.5" voice coil , anyone know a source

[hayseed]

Can u explain how i can do "mated ratings' if i changed out the speakers on the 1510. It has 2x15 , 2x10 and 3 tweeters. I am not entirely sure as to how to wire it or what wattage or ohm speakers i should be looking for.

[Hemisaurus]

Can u explain how i can do "mated ratings' if i changed out the speakers on the 1510. It has 2x15 , 2x10 and 3 tweeters. I am not entirely sure as to how to wire it or what wattage or ohm speakers i should be looking for.

Never heard that term before. I'd guess it maybe means make sure you don't get two different 15's or 10's or three different tweeters, keep them the same sensitivity as each other.

You're going way beyond what I can explain on a forum, without seeing it, maybe someone else will have a go.

[hayseed]

Thanks Hemi. I know it is best to have the speakers matched but in cab with 2 different sized speakers, how does one match it all up?  For example if the 15's are rated at 300 watt, should the 10's also be rated at 300 watt?

[Hemisaurus]

If it's just like an instrument cab, with no crossover, then yes you match them, or use the cab at the rating of the weakest link, if you had a standard 4 driver cab, all drivers 8 ohms, and you had 2 200W 15's a 400W 10 and a 100W 10, the weakest link is the 100W 10", as the cab is series/parallel wired, and the drivers all have the same impedance, each driver is getting an equal share of the power, so the maximum power you can run is 4 x the weakest link, so 4 x 100W so you have a 400W cab.

If you have a crossover, then it's all way more complicated, as different frequency ranges require different power levels, basically your bass drivers need to be big, but you mid-range less so, and your tweets even less. Go with the ratings of what was originally in the cab, you can't go over the power rating of the crossover anyway, as you will blow the crossover itself.

Seeing as Google just returns your request on multiple forums, go call Peavey and ask them what they put in it. 1-877-732-8391

[hayseed]

i did. They have no info documented due its age. They said it was one of the first Peavey cabs built! The only info they had was it used CTS speakers and Piezo tweeters,4 ohms, and that i shouldn't be pushing more than a 100watts through it again due to the age. The guy i am getting it from uses the same head i do and said there is no  problems(Sunn Coli 300) which leads me to believe that it may not have orig speakers in it. He is sending me more pics of it tonite. I will forward them on.

Thanks for the wiring info btw.

[Hemisaurus]

i did. They have no info documented due its age. They said it was one of the first Peavey cabs built! The only info they had was it used CTS speakers and Piezo tweeters,4 ohms, and that i shouldn't be pushing more than a 100watss through it agian due to the age. The guy i am getting it from uses the same head i do and said there is no  problems(Sunn Coli 300) which leads me to believe that it may not have orig speakers in it. He is sending me more pics of it tonite. I will forward them on.

Thanks for the wiring info btw.

PM they guy called paul on the Peavey forum, he seems to have stuff they don't.

[Instant Dan]

Help me amp wizards!

Plugged in tonight and noticed a very loud hum with some popping when adjusting the preamp volume on my 2204. The hum is loud in the lo-input and louder in the hi-input. Normally, I decided to fiddle around with the preamp tubes, put in a spare EHX tube in the V2 slot and sure enough it drastically reduced the hum to almost zero. Then after a few minutes it came back along with the popping in the preamp volume.

I noticed when I would touch my guitar cord on the lo-input the hum would stop and then start as soon as I took my hand off it. On the hi-input it would just buzz endlessly. I am guessing some grounding issues with the amp?

Also when turning my amp off I noticed a clicking noise as if the tubes were being 'pinged' at.


What is going on?

EDIT: Decided to reinsert the power tubes to see if that was the problem. Turned it on and there was a loud screeching hum. Turned it off.

Turned it on again, no sound, dead.

[VOLVO)))]

Tubes. Replace them all. Check bias.

Neither of the fuses blew?

[Instant Dan]

It turns back on and all three preamp tubes light up. One of the power tubes do not. I am guessing it is the tubes and it is the end of their life.

[VOLVO)))]

It turns back on and all three preamp tubes light up. One of the power tubes do not. I am guessing it is the tubes and it is the end of their life.

EL34s? If that buzz went away when you touched anything involving the strings, there is also a ground issue. Report in when new valves are in place...

[Hemisaurus]

Little odd that you replaced v2 not v1

If the buzz is louder on the hi than the low, it's going to either be in the very first tube stage, or outside the amp entirely. Did you have pedals in line? Were they connected to a power adapter?

Does sound like it's toasted now, if one of the power heaters has gone. Did youi try swapping them over see if the problem followed the tube? With the amp in standby, only the heaters should be on, so you don't risk toasting anything else, so go ahead and try it, if you like.

[Instant Dan]

Yes EL34's, Ruby's to be exact.

Yeah I had pedals in line connected to a power adapter but even when i plugged straight in, it didn't do anything good, still lots of hum.

I didn't change tubes while in standby if that is what you mean, too scared after all the horror stories amp techs tell you of being electrocuted to death.

I hope you don't mean toasted in the sense I blew something other than the tubes.

[Instant Dan]

Well I guess that is what I get for messing with the tubes again late at night and tired. I was trying the switch around method that hemi recommended and I somehow (even with being ever so gentle) managed to snap off the main male plug of the EL34 tube into the tube socket (pic for reference)


Now I am just going to leave this to the professionals and try and find a tube doctor in Houston and honestly there are none.

[Hemisaurus]

Geez, don't change tubes with the power on

Never work on your amp with the power on, unless you really know what you are doing.

I meant that you only need turn the amp onto standby, after you had swapped the tubes, you didn't need to turn it all the way on.