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Old 3rd January 2007, 02:12 PM   #11
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Default 6sn7 was used as a line amp but not power amp.

You'd get flea power. Enough to drive headphones only. Maybe a Lowther or a WE755. But I'm sure it would clip readily if you tried to drive any other speaker. You're looking at a 10,000 ohm primary impedance on the output transformer.
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Old 4th January 2007, 12:41 AM   #12
JandG is offline JandG  United States
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Default mmmmmm I am not running Lowther &

it drive's the B200's fine in a bi amp setup. I am also triamp capable,, but no need at this point with the B200's.
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Old 4th January 2007, 01:19 AM   #13
lndm is offline lndm  Australia
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Originally posted by grhughes You're looking at a 10,000 ohm primary impedance on the output transformer.
So if you used two 6SN7 bottles, you'd want 2k5 on the OPT and have 10W of plate dissipation. Not bad, similar to a 6V6 at 3k5 and 12W.

I can imagine some getting quite excited about this for a bedroom/office system or a truly awesome high efficiency setup.
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Old 4th January 2007, 01:32 AM   #14
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I am not a tube expert - but 6SN7 and 6DN7 looks very alike to me
The 6DN7 has the same pinout as the 6SN7 and they both were used as the vertical oscillator / output stage in TV sets, although at very different power levels. That is where the similarities end.

The 6SN7 was used in 1940's vintage TV sets with shallow deflection angles requiring low power. As TV sets got bigger, and the deflection angle got larger, more vertical amplifier power was needed. This gave us the 6BL7 and the 6BX7. These tubes are basically 6SN7's on steroids. Both triode sections are identical but capable of dissipating twice the power of a 6SN7. These were used in 1950's color TV sets up to 21 inches with a 70 degree deflection angle.

The 6DN7 (and the 6EM7, 6EA7, and 6GL7) were developed for TV sets with 90 and 110 degree deflection angles (requiring more power with linearity). The two triode sections in these tubes are NOT identical. One section is small (and similar to a 6SN7) intended for the vertical oscillator, while the other section is much larger (like a 6S4 or half of a 6BL7) intended for the vertical output stage. Similar tubes were developed that used 9 pin or compactron sockets.

All of these tubes have been succesfully used in audio applications, including the previously mentioned S.E.X. amp. All could be used to build a power amp, although the 6SN7 would be hard pressed to deliver much more than a watt. I have built amplifiers with all of the other tubes. They all sounded great, but could not deliver the sound of a TubelabSE with 45 tubes (so they were dissasembled). The tubes are however far cheaper than 45's, and could be used to build an excellent low cost amp.
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Old 4th January 2007, 01:36 AM   #15
Zen Mod is offline Zen Mod  Serbia
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I think that these Tamuras from Sony RtR are in ballpark of 5K:8E + 600E
I have one pair and they are........little wonders .
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Old 4th January 2007, 01:37 AM   #16
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Bah! I drew one a long time ago, and build something related. 12AU7s are cheaper though, and if you still think they distort, it doesn't matter in PP AB1 (AB2 ideally, but good luck squeezing much out of those high perveance 12AU7 grids).

Click the image to open in full size.

ZNFB, so SL7 isn't needed. Yeah, I know the resistor numbers don't add up. Hmm, R4 should probably be smaller, at a glance that looks odd. Instead of plate resistors, use cathode resistors -- more typical values on the order of 100 to 470 ohms, depending on how much cathode resistor (R20) you want to make individual. Also an option: eliminate R20 and use fixed bias.

The one I built:

Click the image to open in full size.

Click the image to open in full size.

Fixed bias class AB1. About 1W per 12AU7. Recommend replacing drive transformer with a 6SN7 follower... drive transformers (at least cheap ones like this) suck.

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Old 4th January 2007, 05:30 AM   #17
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Default Re: I am new to amp tube building but have

Originally posted by JandG The OT's I installed are rumourned to be Tamura from a Sony RTR. & I think are 5k -8ohm also with a 600ohm tap, which I have no clue what that is for.. line..?
TamRadio (tamura) OPTs, 5k>8 ohms. The 600 ohm tap was used to drive the heads, could be used to make the amp a pre or to feed a sub amp (while retaininf the tube amp flavour)

Excellent OPT. I've still hot 5 stashed away (sold 3 or 4 other prs)

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Old 3rd March 2007, 11:59 PM   #18
JandG is offline JandG  United States
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Default Another 6sn7 SET amp..

This one is going thru a thrash at the moment,, will see.. it is very quiet..NFB 1.5w using supposed Pilot iron.I did not build this, I picked it up from a tube freak. clean build..I got it high passed & we will see..running @ 250v I think. Doesn't seem to have a great imaging, as many of my other amps do..mmmmmmm I will just have to wait & see.also how in the heck is this guy useing what probably is PP iron..???
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Old 9th March 2010, 09:00 PM   #19
kunja is offline kunja  United States
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Default Old thread, but wanted to confirm that 6sn7 se amps are great!

I stumbled onto this old thread and wanted to put in a word or two about my se 6sn7 amp. Mine was built by Jermey Fix, and I bought it from him on eBay about a year ago (2009).

With a decently hot preamp in front of it, in my case a Minimax, this thing is amazing! Bass is slightly shy but the imaging is so good it is wonderful.

I've put it up against three 300b amps of various makes, a nice 45 amp with western electric outputs and various el-84 and t-amps and this little one watt wonder bests them all in imaging and "you are there" palpability.

Single ended 6sn7 really is worth looking at.
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Old 9th March 2010, 11:40 PM   #20
Cassiel is offline Cassiel  Libya
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I agree with you kunja. I'm using GE 6SN7GTB tubes (higher max. dissipation)
with a PP 1609 10K Hammond OT. I'm using the 4 ohm tap with an 8 ohms speaker so the tube sees 20K.

370 volts, 15 mA current. A sound I've never heard before. Problem is that it clips, needs a 100dB speaker. Better than 45's and 2a3 amps.
Best SE amp.
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