[BillB]

I completed my point to point 6T9 amp today...it had been shelved for a long time and I finally got to busting butt on it this week.

For those who don't know the 6T9 is a compactron that has a triode and a 12w Pentode in one tube. The amp is available as a PCB but I wanted to try point to point.

Transformers are Edcor's Power-105 for power and the GSXE-5k=15-6. PSU has 880uf of capacitance and I used a chip resistor in the RC circuit.

The front box has a carbon fiber plate and the back is a painted black piece of Lexan.

I put a switch in for UL and Pentode mode as well.

Sound is nice, real mellow and laid back but decent detail and a huge soundstage. A lot of bass output for a few watts too (specs list 4.6w but it is said only 2 or so are clean). I was able to get 85dB at my chair out of my Rocket 760s.

[Niteshade]

That's sweet!    Like the separate power supply.

[vinylkid58]

Nice work, the amp looks great.

I'm planning to build a 6LU8 se amp. Wish me luck.

Jeff

[BillB]

Best of luck!

300B is my next one...go for broke I guess.

I am itching to build an EL84 preamp though...for some reason it intrigues me.

[Freo-1]

Very nice, Bill!   

[JoshK]

Very cool.  I love the looks of compactrons.  I have a nice one here that I was thinking of using for a janus regulator. 

Where did you get the carbon fiber plate?

Couple quick points.  1) the GSXE OPTx is technically for guitar amps, how is the bass and the highs? 2) Watch out that noone touches those terminals on your OPTs as they have HV on them.

Nicely done man!

Josh

[vinylkid58]

Best of luck!

300B is my next one...go for broke I guess.

I am itching to build an EL84 preamp though...for some reason it intrigues me.

Thanks Bill.

The compactron/tv tubes intrigue me, possibly in the same way the EL84 beguiles you. Would the amp be SE or PP triode?

Jeff

[BillB]

I lust after the Audio-Note 300B interstage monoblocks.

There are a ton of compactrons out there...most not so useful.

Here are the insides:

Amp side:

Power side:

[f2a]

Nice 'and one question  : how a but rectifier? 

[BillB]

Haven't gone down that rabbit hole yet...

[f2a]

It seems tube rectifier like gz32 from mullard is best chose  for  your project . also so beautiful … 

[BillB]

Missed this question:

"Couple quick points.  1) the GSXE OPTx is technically for guitar amps, how is the bass and the highs? 2) Watch out that noone touches those terminals on your OPTs as they have HV on them."

The GXSE is rated lower in the bass region and the same in the highs, the guys at Edcor are actually thinking about replacing the XSE series altogether.

And yes, the terminals are insulated.

[BillB]

Added a NFB switch, I now have 3 options to choose from. 

[f2a]

Added a NFB switch, I now have 3 options to choose from. 

Good idea    but Is it   useful for listening music ? do you remember  with famous model  of  hi fi tube amps  not guitar amps ?
With this switch user  can control  treble and
low frequency   and mid ?  how we can find the  best condition ? maybe the optimize point  is between of switch step .

[BillB]

I have found it slightly useful so far. It really makes the amp range from forward to downright dark. Using it in dark-mode could seriously help a bright recording and using it all the way in the other direction makes acoustic music sparkle. Middle setting is "stock".