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Super Champ Build - not loud enough?

1/24/2004 3:51 PM
Mark S	Super Champ Build - not loud enough? Well, I think I finally completed my first amp build but I have some questions that hopefully someone can clarify for me. The amp is not nearly as loud as I expected. It is basically a super champ - a champ with an extra 6V6GT wired in parallel. I assumed this would give me a 12 watt amp (6 watts per tube), but I don't think it's nearly that loud. Here are the specs on the amp: Hammond 270CAX PT 5Y3GT rectifier tube made by Sovtek 12AX7WA preamp tube made by Sovtek 2 6V6GT tubes made by Electro-Harmonix (Sovtek) Hammond 125J OT Jensen Special Design C12R (cheap speaker, but money's tight) The kit I built is a "head" and not a combo, but I plan on building a cabinet and making a combo out of it. So currently the speaker is not housed in any type of cabinet (it's just sitting on my desk). So I'm sure that has something to do with the lack of volume, not to mention bass (though it still sounds surprisingly good IMO). One thing I'm not certain about is the wiring of the output transformer secondary. The speaker is 8 ohms. It took me a while to figure out how to wire up the speaker output jack (a switchcraft), and the documentation I have isn't real clear to me. Here's how I wired the output jack: Ring lug: Green wire from OT; ground wire from star ground lug; jumper from ring to shorting lug Shorting lug: jumper coming from Ring lug Tip: white wire from OT, and yellow feedback wire (coming from a 22k resistor on the wiring board). The wiring data for the OT is located here: http://www.hammondmfg.com/125J.html Could one of you experienced guys look at this and tell me if I did something wrong? I played through the amp for about a half hour, and nothing blew up or smoked or anything. What shocked me the most is that there is absolutely no hum or noise from the amp. And the sustain is the best I've ever heard from a clean amp (I haven't been able to turn it all the way up and play full out yet but will do that tomorrow; that said, I did turn it up all the way and hit a few notes to check the volume and as I said earlier in the post it doesn't seem like 12 tube watts loud - my only reference being a Fender Pro Jr I used to have a few years ago that I couldn't turn up past 1 or 2 on the dial or it was too loud for the apartment I had at the time). As for voltages, I think I'm running a little high on those. After first completing the amp and quadruple checking everything, I inserted just the rectifier tube and then checked the voltage between the first 6V6 socket Pin #3 and ground. I got 391vdc. My spec sheet says that 375 is the max tolerance, but I'm thinking (probably incorrectly) that my higher voltage is because of the beefed up PT I have? Then, with the rectifier tube still in, and this time one of the 6V6 tubes, I got 321vdc between pin#3 and ground, so it did drop as expected, but is still slightly above what my instructions say is within tolerance (maximum of 315vdc). Any ideas?

1/24/2004 3:51 PM

Mark S

Super Champ Build - not loud enough?

Well, I think I finally completed my first amp build but I have some
questions that hopefully someone can clarify for me.

The amp is not nearly as loud as I expected. It is basically a super champ -
a champ with an extra 6V6GT wired in parallel. I assumed this would give me
a 12 watt amp (6 watts per tube), but I don't think it's nearly that loud.

Here are the specs on the amp:

Hammond 270CAX PT
5Y3GT rectifier tube made by Sovtek
12AX7WA preamp tube made by Sovtek
2 6V6GT tubes made by Electro-Harmonix (Sovtek)
Hammond 125J OT
Jensen Special Design C12R (cheap speaker, but money's tight)

The kit I built is a "head" and not a combo, but I plan on building a
cabinet and making a combo out of it. So currently the speaker is not housed
in any type of cabinet (it's just sitting on my desk). So I'm sure that has
something to do with the lack of volume, not to mention bass (though it
still sounds surprisingly good IMO).

One thing I'm not certain about is the wiring of the output transformer
secondary. The speaker is 8 ohms. It took me a while to figure out how to
wire up the speaker output jack (a switchcraft), and the documentation I
have isn't real clear to me. Here's how I wired the output jack:

Ring lug: Green wire from OT; ground wire from star ground lug; jumper from
ring to shorting lug
Shorting lug: jumper coming from Ring lug
Tip: white wire from OT, and yellow feedback wire (coming from a 22k
resistor on the wiring board).

The wiring data for the OT is located here:
http://www.hammondmfg.com/125J.html

Could one of you experienced guys look at this and tell me if I did
something wrong?

I played through the amp for about a half hour, and nothing blew up or
smoked or anything. What shocked me the most is that there is absolutely no
hum or noise from the amp. And the sustain is the best I've ever heard from
a clean amp (I haven't been able to turn it all the way up and play full out
yet but will do that tomorrow; that said, I did turn it up all the way and
hit a few notes to check the volume and as I said earlier in the post it
doesn't seem like 12 tube watts loud - my only reference being a Fender Pro
Jr I used to have a few years ago that I couldn't turn up past 1 or 2 on the
dial or it was too loud for the apartment I had at the time).

As for voltages, I think I'm running a little high on those. After first
completing the amp and quadruple checking everything, I inserted just the
rectifier tube and then checked the voltage between the first 6V6 socket Pin
#3 and ground. I got 391vdc. My spec sheet says that 375 is the max
tolerance, but I'm thinking (probably incorrectly) that my higher voltage is
because of the beefed up PT I have?

Then, with the rectifier tube still in, and this time one of the 6V6 tubes,
I got 321vdc between pin#3 and ground, so it did drop as expected, but is
still slightly above what my instructions say is within tolerance (maximum
of 315vdc). Any ideas?

1/24/2004 9:51 PM
Don Symes	The thing to keep in mind about power is that 2x the watts is a pretty small increase in loudness - about 3dB - with the same speaker/cabinet. A more effcient speaker can make a much bigger difference. Try a few different cabs if you have the opportunity.

2/29/2004 3:15 AM
bd	The speaker wthout a cab isn't going to work too well!!!!! Also that speaker is not too a good a choice. If you can build a bigger cab like the size of a deluxe (non-reverb)and a semi-opened back with a better speaker, I mean a higher SPL like a webervst. You will be surprized how loud it will be then.

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