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mpc 19th August 2012 11:52 PM

Some q after finishing SSE
 
Hello!

Finally after, I don't know - 3 years or more, I managed to overpower my laziness and finished wiring SSE to test how it sounds. It was a great "IT LIVES!" moment, but still I have some questions as I have no idea what is what.

So I adjusted the currents for 12AT7 tube - 10.5 mA in each half. But my question is - how important is to match currents in the output tubes? I am using some old soviet 6П3С (6L6 I guess) tubes which are not a matched pair. I am using 820 Ohm cathode resistor for this, which gives 44 mA and 39 mA Ik respectively. Is this OK? Also at this current the power dissipation on cathode resistors should be only around 1.3W but those resistors are hot like hell - 90 degC. In case it is important the B+ is around 392 V.

As I was not sure how to wire the cathode feedback I just grounded the cathode feedback capacitor. The output transformer (Edcor GXSE15-8-5k) has yellow (8 Ohm) and white (Common) wires - which one goes to CFB :blush: ?

So I have been listening to this for more than 6 hours (I am still listening as I type) - yes I have a low sensetivity not so splendid quality pair of speakers, and I have noticed the sound feels like someone has played with the equalizer to bring out the lower end more ( I guess what I am trying to say - the sound is not crisp - piano sounds like crap, voices are dull? [can I describe it like that?]) What might be the cause for this - can I do something to improve this?

Thanks!

cjkpkg 23rd August 2012 01:56 AM

I would try without feedback first. Jumper the output terminals on the board and hook the OPT secondaries directly to the speaker terminals. Edcor is good iron so you may not need the feedback.

What coupling caps are you using? I think you want nice caps here but no reason to go boutique here.
Jantzen silver z are in my amp now and they are my favorite so far.
Auricaps
Solen
Russian k40y-9

To name some others that are proven.

What value coupling caps?
I would recommend .33-.47uF with at least 600v rating.

As far as balance you are not that far off so I suspect that is not causing any negative sonics.

The SSE is one of my favorite sounding amps I have built so suspect a faulty or non ideal value component based upon what you describe.

cjkpkg 23rd August 2012 02:05 AM

Also are you running triode or UL?

lastly many folks have had optimal results with el34 and kt88 tubes with the corresponding cathode resistor.

mpc 23rd August 2012 09:09 AM

I have hooked it in UL mode - haven't tried the triode yet (but I will). First I listened without feedback, and then I managed to to poke around and get the feedback going. I think that with FB it sounds better (pretty much I like it).
For coupling I use K73-9 0.22 uF, I might look for the paper ones...if you say they are that much better.
I will try EL34s later - now I want to get things going with 6P3S (they are so cheap - like $2.50/ piece).

cjkpkg 23rd August 2012 12:27 PM

What I can tell you is that getting the voltage and current up on this amplifier it really sings, FB, no FB, UL, Triode, Pentode all then become personal taste.

I would definitely try the PIO, they are cheap and good.

I run mine at about 450V and around 90mA per tube and it really rocks.

Davec113 9th September 2012 03:15 PM

Could just be your speakers.... they don't sound ideal for the SSE and low-eff, hard to drive speakers can sound like poo with a SET amp...


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