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A Very Compact Hybrid Amp - Page 94

post #1396 of 2201
5/22/09 at 11:12am
Quote:
Originally Posted by Forte View Post
Have only had a short listen today but the 6CG7 sounds fantastic, one of my favorite tubes already.
Yes, a very nice tube.


RDS- Nice looking! I am considering including that switch as part of the next round (Holland has suggested a smaller one as well), as stocking issues will force a kit part change most likely...
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post #1397 of 2201
5/22/09 at 5:07pm
Quote:
Originally Posted by Forte View Post
Talking of underheated tubes, got what was supposed to be two 6FQ7/6CG7 tubes from eBay today. One is fine, but the second is a 8FQ7/8CG7(8.4V heater), was going to return it for a refund but after reading your post plugged it in and it sounds great even at only 6.3V!

Have only had a short listen today but the 6CG7 sounds fantastic, one of my favorite tubes already.
They are my tube of choice for many an amp.
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post #1398 of 2201
5/22/09 at 6:25pm
There was a reason stax chose them (6FQ7 at least) and I have to agree, they are by far my favourite tube ..dB
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post #1399 of 2201
5/23/09 at 4:31pm
This might seem like a silly question, but when do I use the 12.6 V setting and 6.3 V setting.
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post #1400 of 2201
5/23/09 at 5:13pm
Quote:
Originally Posted by lgn View Post
This might seem like a silly question, but when do I use the 12.6 V setting and 6.3 V setting.
Ditto, it's not like the tubes come with instructions. I would have no idea myself.
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post #1401 of 2201
5/23/09 at 5:56pm
Quote:
Originally Posted by lgn View Post
This might seem like a silly question, but when do I use the 12.6 V setting and 6.3 V setting.
Mostly from this old post to this thread

12.6v heater:
12au7 variants
ecc82
6680
6189
5963
7316
5814
12bh7
8416 (12.6V 6922)

6.3v heater:
6922
6dj8
6n1p (a bit much draw?)

And some are running 7v/8v tubes @ 6.3v as just posted & there may be a couple more tubes than this list.

A way to confirm is to search for the tube's datasheet (e.g. 12bh7 pdf) - series heater voltage. There are some tube info repository sites too...
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post #1402 of 2201
5/23/09 at 5:59pm
Thread Starter 
In general, and obviously so, tubes that start with 12 should use the 12.6V setting. Tubes that start with 6 use the 6.3V setting.

But then we get into the European labeling system with the ECC types and you just have to look them up.

Then there are the pure numbers. These are frequently military or specialized versions of the normal tubes. Some are made more rugged for example, or low noise.

You'll have to look these up too.

Try this website:

Frank's Tubes

It has nearly everything that's ever been produced.
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post #1403 of 2201
5/23/09 at 10:39pm
I am done the amp now but it seems that the led starts off as green, red never shows up. Also it seems that the amp on full volume doesn't seem to be very loud on my k702. I haven't tested the voltages yet and I will get to that asap, but any suggestions before that?

Thanks
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post #1404 of 2201
5/24/09 at 12:22am
Thread Starter 
Ign, there isn't much else to do but to start measuring voltages.

First question is, are the green and red LEDs in the right places? If so, you're saying that the red LED never lights up and that the green comes on immediately?

If you could please measure OG with respect to SG and then OL and OR with respect to SG this will get us started.

Thanks.
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post #1405 of 2201
5/24/09 at 5:25pm




more pics in build gallery
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post #1406 of 2201
5/24/09 at 6:16pm
Quote:
Originally Posted by zkool448 View Post




more pics in build gallery
ABSOLUTELY STUNNING! yes, i was yelling.

Ummm, would be better if the HP jack was in front, ya think?
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post #1407 of 2201
5/24/09 at 6:29pm
Very pretty zk, as always

Alex, thanks for the tube info/tips.
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post #1408 of 2201
5/24/09 at 9:05pm
nice work, zk. you have too many tools, and obviously too large a workspace.
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post #1409 of 2201
5/24/09 at 9:44pm
Quote:
Originally Posted by zkool448 View Post
more pics in build gallery
Very, very nice!

How's it sound?
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post #1410 of 2201
5/25/09 at 12:06am
Thanks guys! This little guy is a really really nice amp and I can't wait to get this setup at the office tomorrow.

Been following the tube/tweak thread and gathered few ideas on which tubes to try. Good tube reviews except strangely, I can only relate particularly to adamus' tube impressions -- will likely go with his recommendations in terms of tube selections

headphoneaddict, the hp jack would've been good in front, sadly that huge honkin knob took up all the real estate.

I do like the RK097 pot with the on/off switch built-in, saved me from drilling an extra hole. I thought I'd get some hum when I ran an ac wire to the front (one side of board) but fortunately did not introduce any negative effects whatsoever.
cheers.
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