Another Simple SE builder

[Ty_Bower]

Took this photo last night... I thought it was neat.

[Tam Shaun]

Please post the schematic.

[tigrine]

Go to George's website.

tubelab.com

[Zap]

Ty,

How do you like the sound of the 6CA7s? I have a pair, but I found them to be less pleasing (more dull?) than the EH KT88s I have and use most of the time.

What value are you using for the bias resistor?

Thanks

[chrish]

My favourites are EL34 in this. Have tried JJE34L and 'wing C' EL34, both nice. To me, in my setup, the EL34s sounded more detailed than the JJ KT88s I have. Have also tried 6P3S-E (Russian 6L6), not too bad either, almost as good as the EL34s.

[w5jag]

Great job!

After you have some time to listen, please share your views on how the Transcendars sound with/without cathode feedback.

I had both 3K and 5K Transcendars on mine and never felt the need to apply cathode feedback to them. I have Hammond 125ESE mounted up right now, and they definitely benefit from cathode feedback.

Not sure that a Simple SE should hiss; mine is tomb quiet.

Win W5JAG

[Ty_Bower]

Thanks to all for the compliments!

Originally posted by Tam Shaun
Please post the schematic.

Here's a link to the George's site:
http://tubelab.com/AssemblyManualSim...ematic_SSE.htm

Originally posted by Zap
How do you like the sound of the 6CA7s?

What value are you using for the bias resistor?

So far, I like the 6CA7-EH. I haven't tried anything else for comparison, though. I've got the New Sensor KT88 (seen in post #7) and some old WWII era 6L6GA (post #12 & 13). I intend to try the KT88, but I don't dare stick in the 6L6GA with the kinds of B+ I've got right now.

Originally posted by chrish
Have also tried 6P3S-E (Russian 6L6), not too bad either, almost as good as the EL34s.

I've thought about them, but again I'm worried the B+ from the Hammond is too hot. Of course, for $30 a quad, do I mind roasting a couple to find out?

Originally posted by w5jag
After you have some time to listen, please share your views on how the Transcendars sound with/without cathode feedback.

Not sure that a Simple SE should hiss; mine is tomb quiet.

My initial impression is that the Transcendars sound fantastic. Easily worth the $100 I spent on the pair. I did ask Gery to add the UL tap, and that's how I have them hooked up. The power tubes have screen grids, so why strap them as triodes? Figuring that's going to impact their damping, I went ahead and connected the cathode feedback too. I didn't install switches, but it's easy enough to rewire it without UL and feedback. Sooner or later, I'll get around to trying it that way. As they are now, the bottom end is very satisfying - no complaints here.

The hiss is nothing major, and not something you'd notice from the listening chair. You have to walk up to the speaker and put your ear to the tweeter to hear it. Regardless, it is there and it's noisier than my ST35. Perhaps I should try a different 12AT7? I've got a HP labelled GE in there now. Somewhere around here I've got a Telefunken. I guess I ought to go look for it. The overall high gain of the amp still seems a little weird to me, though. I can't help but wonder if I somehow swapped a set of resistors or something.

[chrish]

I have a three position switch for selectable cathode resistors. KT88, EL34, 6L6. The 6P3S-E are fine, the 6P3S show signs of red plate in the amp.

Cheers,

Chris

[tubelab.com]

I had dummy 8 ohm loads connected during feedback testing, and I was surprised the music was so audible.

I never heard much music come from a tube (heating, crackling and poping, yes) but the OPT's WILL sing to you. Some are louder than others. You don't notice it with speakers kooked up because they are much louder.

Perhaps I should try a different 12AT7?

That is the first place that I would look. The second place would be a noisy resistor. I have not had an amp hiss at me yet. Does the hiss change with the volume control? If so disconnect your input cables. If not, remove the 12AT7. If the hiss goes away the problem is in the 12AT7 circuit.

[Ty_Bower]

It could be the output transformers. I assumed it was the tubes.

I tripled checked every resistor, and they are all correct. I swapped out the GE 12AT7 for another GE. The results are pretty much the same. I noticed that at least two thirds of the hiss is coming from my Adcom preamp. If I switch it off, things are quieter. I hadn't noticed with my ST35 since it doesn't have as much gain as the Simple SE.

In all seriousness, I'm being fanatically picky about the hiss. I've been told I have ears like a dog, and I can hear a computer monitor that's been left turned on in another room across the house.

I'll try pulling the 12AT7 and power up the amp, but at this point I think there's not really a problem here. I might try to rig up a simple fixed voltage divider at the input to attenuate the input signal.