Huss style 6v6 Plexi

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zaphod_phil
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Post by zaphod_phil »

Sure, that would also work fine. Like I said there are plenty of 1987 Plexi layouts kicking around the net.....
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Post by markh »

I recently built a 4 x 6V6 high gain amp (Soldano-ish preamp) that sounds killer. I love the 6V6, it's a great little tube AND there are still NOS deals to be found.

--mark
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redwood
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Post by redwood »

redwood wrote:Is there any reason not to take the ceriatone layout for the 1987 and use it but with 6v6's in place of the el34's? for this amp?Will you still get the sparklingshimmeryliquid clears and layers and layers of rich creamy harmonics?
Built this way it's gonna be running a bit hot ,probably about 430v.Thats a bit much for NOS tubes isn't it?I was thinkin new JJ's would be in order.What do you suggest Mark?
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Bulatovic
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Post by Bulatovic »

if voltages are high on 6v6s is it possible just to add a couple of zenners like 30V or so to get the voltage down a bit? Isn't 430 a bit too much close to the JJ 6V6's maximum of 450?

Thanks
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redwood
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Post by redwood »

I think Mark was running right at 435 on his 6v6 plexi,its up there though.
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Post by phsyconoodler »

Just use good 6V6GT's and the voltage is not a problem.If the amp is set up for EL34's the 6V6's sound a little different with 1k screen resistors and 5.6k grid stoppers.But leave them alone so you can pop in EL34's if you want.The volume level will not be dramatically different.I prefer EL34's overall to 6V6's but there is something about 6V6's that sound better with single coils.I find that I don't have to change anything to get the bias right.Just use a 50k bias adjust pot.
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Post by martinw »

My 6V6 October (very similar to the Huss Plexi) runs lower B+ (around 390 IIRC) and sounds truly wonderful.
Maybe I lose a little volume and headroom? Not really an issue to me.
I do like having the "Ali" option on the October though. Worth considering for the sake of a switch and a couple of components.
Check it out: 6V6 October
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Fredaxis
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Post by Fredaxis »

Very nice October Martin :wink:

Waiting for my chassis, I prepared some other parts today, and found on the web the schematic of the Motorola console from which I got the PT and OT.

Let's go for the newby questions :)

- The schem tells the voltage right after the 5y3 is 320V. From that I guess the PT is about 290/0/290, that should give me about 400V on the plate with the SS rectification. Am I right with the math?

- The heater side of the PT is not center taped, Guess I'll go with the 100k/100K pseudo center?

- On Mark's schem, there is a 470nF cap in parallel with the 1st PSU 50uF cap. What is the purpose?

- My chassis has room for 3 cap can, I end up with one more 50uF section than needed. Would it worth to parallel the 2 sections of the 1st one in the PSU to make it 100uF as in the 1987?

Thanks in advance for your answers
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Bulatovic
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Post by Bulatovic »

No, you want 100R for an artificial center tap.
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Fredaxis
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Post by Fredaxis »

Ouch!! You are right! typo, thanks for correcting 8O
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Post by Fredaxis »

Anyone on my voltage and caps? :roll:
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Post by morcey2 »

Fred,

On the can caps, paralleling one to give you a 100u cap would be good. With the 290-0-290, you'll probably end up with just under 400V under load. The tranny I have for mine is 300-0-300, so it will be awefully close to what you've got.

As for the 470n cap in the PSU, I think that's to better filter some of the higher frequencies that the electrolytic caps don't do as well, but that's just a guess.

Matt
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Fredaxis
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Post by Fredaxis »

Thanks a lot Matt.

So it is a go for the 100uF.

290/0/290 is only a guess I made based on the 320V with the 5y3 in the circuit. Anyway, about 400v should be OK for the plexi.

Thanks for the idea on the 470n. Mark is asking for a metal film here. He will may be confirm.
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Post by martinw »

Fredaxis wrote:Very nice October Martin :wink:
Merci!
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