Plate Voltage on my Asteroid/Concorde Clone

[skhan007]

Hi Guys,

Just got my asteroid/tribute/clone amp and found that she's running 507v DC plate voltage. I was really surprised to see this. Is it common knowledge that these amps run such high plate voltages?

She's biased up perfectly otherwise. EL34's are set to 65% at 32 mA each.

thanks,

Khan.

[tubedogsmith]

What's your wall voltage?

[gearhead]

Voltage seems a bit high. Believe it's supposed to run more in the 475-480 range.

[Roe]

a k60 run at 485ish with el34s and a tube rectifer. doesn't this one use the same PT? If she does, then around 500v sounds about right (depending on wall voltage and bias settings)

[Noel Grassy]

skhan007,
I'm also curious to know your VAC level! My AC supply can go as high as 125~127 volts during the day in the Summer months from heavy demands. This makes all my old tube amps weep and moan.
I wish I could offer help but I'm waiting for a NOS rectifier tube before I can kickstart my Kromet 60. You can imagine my anxiety while my "free concert" is put on hold...

Mebbe you can post the voltages before and after your rectifier?
Later,

NG.

[M Fowler]

My Komet 60 was in the 485 range but bnwitt's was at 504, 503 & 508, 506 so it can vary from builders as you can see using the same PT/OT combination.

Mark

[Roe]

both of the two k60s I've build were around 485v with el34s. but the voltage will vary with different tubes and bias settings

[M Fowler]

Anyone have an extra Komet chassis?

Mark

[skhan007]

Thanks for this info guys. I thought >500v might be on the high side, but it sounds like others have found similar readings on occasion.

Well, at the risk of sounding like a novice (which I am), if there's a safe way for me to use my digital multimeter to check my wall voltage, please let me know and I can report back.

As far as bias, the amp is biased up perfectly. I suppose if I upped the mA draw of the EL34's the PV would come down a bit, but I doubt it would go down to the ~480 range.

[Noel Grassy]

skhan007,
Here's one way to do this;
To safely check the wall voltage I'd set the meter for AC volts and stick the two probes in each vertical slot on the wall outlet. This presumes you're living in the US. I can't comment on wiring methods used any where else.

You should see a fluctuating voltage reading or a sum of averages if you've got a fancy DMM. Copy the figure on paper.

NG.

[skhan007]

Thanks Noel. OK- I am running 122 v from the wall. Given that, do you guys think I should be concerned about the amp running relatively high plate voltage? Should I up the mA draw on the power tubes? Leave it be? Overall, the amp sounds amazing.

[Noel Grassy]

Naw, nothing to worry about IMO.

I saved an old post that states, "The Komet runs at 466VDC on the EL-34 plates...". But a PDF named "Komet Voltages" shows Barry's running at 503 & 506 where Allyn's amp is running 484 on both tubes and biased at -45V.

So I'd close by saying, "Play that muthah!".
Have fun,

NG.

[Allynmey]

Those voltages are fine. A lot of them run that high.

Play it!

[Teleguy61]

Does anyone have PT and OT manufacturers and part numbers
for Komet?
Thanks-
George

[M Fowler]

Answered in other thread George.