2204 with 1 tube?

[wavenator]

i've just finished my ceriatone 2204 jcm 800
sounds great but there is a problem
in the high channel , the gain is much toooooo high
i mean tooooo much high, like a metal amp
and thats not the end, there is no sustain, and the sound isnt clean

well i thought it is a lead dress, i checked all the wires, rewired things, shielded what needed, and still the same problem

now , the amp is a push pull, and i had a problem , and i am using only 1 el34 tube
is that ok? lol , can it cause the distortion?
i mean i have only 1 el34 instead of 2
when i mean distortion i mean my amo sounds like a mesa boogie + without any sustain
thx guys

[Derringer]

why would you run it with only one EL34?

If it's push pull then your power section is only able to amplify about half of the signal

put the other tube in there, bias, and hope that there's no damage to your output tranny

[petemoore]

If it's push pull then your power section is only able to amplify about half of the signal
  More specifically either the + or - excursions, that means, depending on which socket is left empty] the amp is only pushing, or only pulling, so it'd be push..pause..push.., instead of push'pull'push'pull'.
  You definitely need the other tube in there for push pull amplifier.

[wavenator]

i know i need another el34
i am going to buy 1 tommorow
i just wanted to know if it causes the high gain distortion?

[slacker]

Yeah it will cause distortion and the gated effect you've mentioned. I'm not an expert on tube amps but running it with one tube I think you're basically clipping half the signal, so that's where some of the distortion is coming from.

[Zben3129]

Running with missing output tubes only works when the amp has 4 output tubes (octal). Then, you can remove a certain 2 and get half wattage.

You may have done some damage to your OT. I would think it would be fine, but theres always a chance. Don't run it anymore without the other tube, and once you get the other tube see how it runs.

Other major do not is running the amp without a speaker.

Zach

[wavenator]

i never run the amp without a speaker connected, thats known

i think(i wish) i havent done any dmg to the OT

btw
whats tube is better
electro harmonix platinum pair el34eh
or
jj el34l

[Zben3129]

I think the general feeling is that JJ's are the best new production tubes. Also, I don't think electro harmonix have a great rep.(could be wrong on that one)

I personally use JJ's in ALL my amps 


PS - I think your OT should be fine, theres just a small possibility that it was hurt. If you didn't smell anything or release the mysterious blue smoke then your probably fine.

Zach

[eleanor296]

I like my Shuguangs (spelling?) 
IMO really good for I think around 30 for a matched pair.

~Andy

[teletroy]

if you want to only run one power tube to lower the output power you can ground the input of the other el84 (pin 2) - the amp will sound much better than not having the other tube in there You do need two of them in there though, cuz yeah, it probably doesn't sound good with just one tube in there.   quasi se

[d95err]

It should be ok to run a PP amp on one tube (even in a 4-powertube amp). However, if you remove tubes, the voltages in the amp will rise. So, check that the anode voltage does not exceed the rating of the filter caps, and check bias so the tube isn't running too hot. The suggestion to ground the input of the unused tube is safer. That also keeps the hum-canceling of the p-p poweramp going.

What volume are you playing at? Pushing the single-tube hard could perhaps result in unwanted distortion types. If the problem occurs at low volume, it's not the poweramp.

[wavenator]

i have high gain distortion (with no hums or background sound) even in low levels, i mean the preamp is on 11 and master on1
are you sure it is not because i use only 1 el34?
cause 'i've just orders 2 el34

[d95err]

If the problem occurs at low levels it seems likely that the preamp is the problem (no guarantees though). I'm guessing a bad preamp tube, bad solder joint or the wrong component value somewhere.

Good luck!

[DougH]

I guess I don't understand why there is so much interest in solving this err...ummm.. "problem" when the solution is simple- just run the amp as it was designed- with 2 tubes.

[drewl]

Exactly, I fixed many amps that were running on one output tube and the bad sound is exactly how you described.

[wavenator]

ok, ive just put in 2 el34 tubes
the same high gain distortion is there
ill check all joints, all tubes
any other guess what can causes this distortion?

[DougH]

Have you checked with Ceriatone? Do they offer troubleshooting support for their kits? I would check with them first.

[wavenator]

i checked with ceriatone
nik said its a lead dress
well , i rewired all the amp, the same problem

[DougH]

You probably have a wiring problem or cold solder joint somewhere. Check around your 470k/470k attenuators in the circuit. Make sure the tone stack is wired properly- it's a source of loss in a preamp and if it's bypassed somehow you will get a lot hotter signal coming out of the preamp. Double check all resistor values with a meter. Etc...

[Zben3129]

If the preamp is on 11 (is this 11 o'clock or like 11 /12?) then you might be getting preamp distortion? With a MV amp you can get lots of OD with the volume on 1 but the preamp up.

Zach