my new old tube amp--help!

Hey toobmasta, you guessed right, my amp is a Harmony H303A.

So I cranked up the amp to max volume today. F-R-EA-K-I-N-G A-W-E-S-O-M-E. I absolutely love it! I usually play very quiet so I was very self-conscious of my playing but at the same time... how exhilarating! The overdrive was really really awesome so now I have to get an attenuator as soon as possible. What do you guys recommend? I read some posts about smoking dog's attenuator as well as Weber's attenuators. I wouldn't mind building one, I think it'd be a cool project. Does smoking dog's attenuator work well? Does it change the tone at all or not? What about Weber's? I'd like something cheap, preferably.

I'm so happy!!

:o

Oops! I'm responsible for the error. He did clearly say 12AU6, but somehow I had the 12AV6 in mind. I'll be 51 tomorrow, and the old mind's fading fast.

Here's the 12AV6: http://www.nj7p.org/Tube4.php?tube=12AV6

Here's the 12AU6: http://www.nj7p.org/Tube4.php?tube=12AU6

The comments about the series power supply still apply.

I'll be 51 tomorrow, and the old mind's fading fast.

Congratulations and happy birthday! By prevailing GN trend, you should buy a Squier '51 to celeberate :lol:

"She" did clearly say 12AU6, "SHE" :wink:

Thanks for that link Ricochet, I'll try those alternative tubes if I'm ever bored and need to try something new hehe.

About that power supply thing... I'm really ignorant about electronics, could you explain what the problem is in more detail?

Ah, SHE! Sorry!

An AC/DC amp, radio, whatever, doesn't use a transformer on the input to the power supply, so it's hooked directly to the power line. There are two wires coming to the socket in your house. One is a "neutral" wire that stays close to "ground" or "earth" voltage. The other one is a "hot" wire that runs at around 120-125 volts AC, in the U.S. and Canada. (It's around 240V in much of the rest of the world.) To make a complete circuit in your equipment, one side of the socket has to be connected to the chassis, which also is the "ground" for your guitar's signal cable. The metal parts of your guitar are all grounded to the outer shield of your guitar cable, too, so will be at the same voltage as the amp's chassis. It's a direct connection. If the plug on the amp's cord happens to be hooked to the "hot" side of the socket when it's plugged in, your guitar's metal parts are hooked straight to your house current supply. If it's hooked to the neutral, you're OK. But unless the amp has a polarized plug that can only plug in the right way, it's a 50/50 chance which way you get it plugged in.

Another well known amp that's AC/DC is the guitar case amp that Danelectro made and Sears sold.

She? Well, since there wasn't any indication of gender, I too, assumed you were male. Guitar chicks are way cool, but way rare, so whooda thunk.

there are lots of different ways to make an attenuator, but they ALL affect the tone. The better ones can get very pricey. Your amp is a toy. A really neat toy, but still a toy. No point in investing major bucks for a hot-plate. I've used an L-pad before and been quite happy with it on small amps like this. Here's a link to one that's similar to what i used to have. It won't break the bank, and won't go up in smoke driven by your Harmony. Just be sure to mount it somewhere that the heat won't cause any problem. It should get about as hot as a bathroom night-light.
http://www.madisound.com/cgi-bin/index.cgi?cart_id=3D%25&pid=1605

Whoa there Ricochet, you posted while i was typing this.

As i said previously, the H-303A has a power transformer. No shock hazard like an AC/DC radio. The chassis is NOT connected to the neutral of the line. You can convert this to a 3 wire grounded cord, and that's probably a good idea.

OK, you know the amp. I've never seen one using those 50C5 and 35W4 tubes that wasn't AC/DC. Half wave rectification's unusual with a power transformer. Just because I haven't seen it done certainly doesn't mean it hasn't been done, obviously.

My guess is the H-303 originally was AC/DC, but never found it's way to market. Unlike a radio, even if you have the chassis unaccessable to the user, plastic knobs and all that jazz, the guitar is still connected to the chassis. Some guy testing the prototype probably got knocked on his butt, and it was hold everything! That's probably where the "A" comes in. Strange thing is, instead of just putting in a 1 to 1 isolation transformer, they had a 48 volt secondary to feed the heaters. Another secondary provided the B+. But both secondaries shared a common lead leaving the transformer, that was connected to the chassis.

Once they realized they couldn't get by, (cheap) without a power transformer, they stuck to "normal" tube sets with 5 and 6 volt heaters for later designs.

That scenario makes sense. Hey, welcome to GN, BTW! :D

I have an old Alamo amp from the early 60's that I picked up, I had an amp guy look at it after the sound started cutting out on it, before that it had such killer sound, instant ZZ top, nice and small, weighed about 10 lbs. I had an amp guy, one of the few around here, look at it he said took part of it apart. then told me it would need a major over haul and he did'nt have time atm. So I got it back from him and set it aside for a couple of weeks, then took the back off and saw he kept the tubes.

That amp had a great sound and I might get it fixed sometime, needless to say he won't be touching it, I'm still a bit agitated about the whole thing.

Scott

Man, that was dirty! Did you tell him you want your tubes back? If he doesn't cough 'em up I'd make sure it got known around the community.

He's looking for them, heh.

I'm thinking about stripping the chasis and using it to build a 1 watter from a kit, have to do some reading before I tackle that, maybe next winter, I have to weld new floor boards in my Duster this winter :)

I have a Epi Valve Special to play with til then.

Scott

Thanks Ricochet and toobmasta for your very intelligible explanations!

I'll look into that attenuator of yours toobmasta (if they sell it in Canada, that is). But I think I'll try to build one too... could be fun. Who knows, one day I could be building amps. Might as well start somewhere!

hey Scott, is that Alamo a Capri? That has the same tubes as A.K.s Harmony. You guys can start a club.

A Duster! There's a classic!

Here's my 'Vette:

:lol: