My amp's too quiet!

[chrisjedijane]

I bought this amp a while ago -



It's a kit that some guy made, and it sounds lovely. The only problem is that it's not really loud enough, and there's next to no headroom out of it. I mean, I use my 6W Champ with Heliopause with the volume at about 4 for every show and practice, and it's still clean. On the couple of occasions that I've used this for practice (running it into the pictured cab's twin brother, a 2x12 with a pair of Vintage 30s in it) it's breaking up at about 2 on the volume control and it's really driven by the time it's at the same volume as the Champ - in fact, I'd say it's quieter than the champ. The head has 2 ECC83s and 2 EL84s, so I should be getting about 18-20W if it's class A, right? It does sound great with that drive on it, but I really need a little more headroom and volume. We're not even a loud band; it's me, an acoustic guitarist and a drummer who plays with brushes most of the time.

I have no idea when the amp was re-valved last. I stuck the 12AX7s from my Blues Deluxe into it to see what happened and I got a little more headroom but there wasn't any overall increase in volume. Help!

[OnlyVees]

Are you sure the impedence is a match? You might want to try that head through a single 10 or 12" speaker, that should give you more headroom.

[chrisjedijane]

Yep, the cab is 8 ohms so it's fine. Putting it through a single speaker won't give me more headroom (in fact, shouldn't a 2x12 be marginally louder?) - it's not the speaker that's the problem. The problem lies in the amp.

[OnlyVees]

I probably fall into the "knows just enough to be dangerous" catagory, but from reading Dave Hunter's wonderful book, The Guitar Amp Handbook, "you might discover that injecting your 15W Orange AD15 through the studio's in-house closed-back 4x12 pulls off an impressive JTM-45 impersonation- while distorting a lot quicker and sweeter..."

It seems your low-power amp is working a lot harder pushing two 12's than it might be running a single 10 or 12" speaker. Hopefully this makes sense, and I'm not an idiot.

[chrisjedijane]

That's generally not how it works - as long as the impedance is correct your amp will have no problems driving the speakers, and won't have a hard time at all. The reason why an AD15 distorts at lower volumes than a JTM45 is that the the JTM is higher wattage, and has to be turned up louder for distortion. This all happens in the amp itself, and isn't anything to do with the speakers (as long as the speakers aren't breaking up, which is another issue entirely). This head has the same lack of headroom through the 2x12 (120W total handling) as with the speaker in my Blues Deluxe (60w into 8ohms, if I remember correctly).

[øøøøøøø]

Here is a list of things to check:

http://www.geofex.com/ampdbug/lowpower.htm

[chrisjedijane]

Thanks! I haven't had the chance to try the amp with new power tubes in it as I don't have any EL84s lying around, but I'll have to give it a go. I guess it's probably due a re-valve anyway.

[OnlyVees]

I'm gonna just sit here in the corner- with my amp book- and be quiet from now on. 

[øøøøøøø]

Thanks! I haven't had the chance to try the amp with new power tubes in it as I don't have any EL84s lying around, but I'll have to give it a go. I guess it's probably due a re-valve anyway.

Worth a try, but from what you describe, I'd first check the preamp tubes and phase inverter.

After all tubes checked, then look into the other stuff.

Since it was made by 'some guy' from a kit, that is a red flag.  I wouldn't be at all surprised if something in there was amiss.

[chrisjedijane]

I'm gonna just sit here in the corner- with my amp book- and be quiet from now on. 

Don't worry, we're all learning here!

Thanks for the help, Brad. I think I'll leave it into the tech to get it checked out.

[øøøøøøø]

I'm gonna just sit here in the corner- with my amp book- and be quiet from now on. 

Don't worry, we're all learning here!

Thanks for the help, Brad. I think I'll leave it into the tech to get it checked out.

probably a good idea!

[TheodorJ]

Maybe you should try adding more speakers? A 4x12 maybe...