Super valve technology

Hi

Here's some pics of my SVT bass amp project.

http://img217.imageshack.us/img217/7479/hpim09876zn.jpg
http://img217.imageshack.us/img217/8760/hpim09797pj.jpg
http://img72.imageshack.us/img72/840/hpim0988small2yv.jpg
http://img72.imageshack.us/img72/2934/svt…minen2073mr.jpg
http://img331.imageshack.us/img331/9374/sv…095small0gs.jpg
http://img114.imageshack.us/img114/5273/sv…minen2080we.jpg

Yours Okabass

Re: Super valve technology

Zitat von Kippekiller

Very nice, is it that heavy it looks like, and does it sound that way?

Thanks!
It weights c. 29 kg. The sound is what you can expect from 300 W tube amp: nothing to add, nothing to take away. Very nice indeed.

Re: Super valve technology

Zitat von MAD

Hi Okabass,
looks good, what PT are you using, custom made? What are the voltages of the PT? I have a 1650W and a custom made PT (with some taps for 450V-600V B+) laying around in my lab, but have no time to build the amp
Regards,
Martin

Vielen dank!

PT is custom made (Muuntosähkö OY, Finland). Voltages are: 6,3 VAC, 27 VAC, 4 x 160 VAC . It is orginally made for 200 W "Voima"-type amp (Circlotron or PPP). I used it for bass about three years.

The amp has appr. 685 V for anodes (three x 160 VAC ) and 450 V for screengrids (two x 160 VAC). The cathode follower -12BH7- has -150 V biassupply (one 160 VAC).

The heaters for 6550 are in series: The 27VAC is rectified to 38 VDC (38/6= 6,3). The 6,3 VAC is for preamp and driver tubes.

The OP trafo is 1650W.

Re: Super valve technology

Zitat von MAD

heater in series? Have you measured the voltage at each 6550? It's common sense, that tubes have variations regarding thr resistance of the heater circuit, so you could get pretty different voltages at each tube, when connected in series. What's your experience?
Regards,
Martin

Hi

I measured the heater voltages. No problem. The difference between the tubeheaters max and min voltage is 1,8 %. The tubes are EH 6550 (Russian). The filament resistances seem to be amazingly close each other. However, the median voltage is on the low side: 5.97 VAC (still in the specs), The 27 VAC feed is a bit too "small".

Naturally,I dont recommend to use series feed. But in my case the option has been a new 6,3 V / 10 A trafo.

It doesn't (at least in theory) matter how you heat the filament. You can use for example open fire, a gastorch ;). I think the important thing is to heat the filament to get the right cathode-emission (what ever that might be). I strongly feel that ± 5% tolerance for filament voltage is best.

Re: Super valve technology

Zitat von bluesbrother

Very nice amp!Do you have a schematic and a layout for this amp?

HI

Thanks!

Sorry, I haven't drawn complete schema or layout. I have dealt with the tubes enough, that I don't really need an exact schema, and make component changes (if needed) mostly by ear.

Offcourse, there are some "building blocks" that I don't (allmost ever) change: those circuits, that you -in my oppinion- can't make sound or last any better.

The poweramp has 6550 tubes and 12BH7 cathodefollower with -150 bias (just like the Ampeg).
The PI is normal 7ender or Marshall type.
The preamp is combination of the original and my own design.

I like to add, that the mid control includes that toroid coil (selfmade), and I feel the Ampegs LCR-filter is the best mid control for bassguitar.

Re: Super valve technology

HI, Again!

Here's some pics of the completed SVT. It's ready to rock!

http://img205.imageshack.us/img205/4317/hpim1067fc2.jpg
http://img291.imageshack.us/img291/6258/hpim1071dx7.jpg
http://img291.imageshack.us/img291/3874/hpim1079it5.jpg
http://img291.imageshack.us/img291/4613/hpim1072cr2.jpg
http://img291.imageshack.us/img291/3746/hpim1078lx1.jpg

Re: Super valve technology

Zitat von Vogul

hey what's the use of this counter?

HI

It counts the wrong notes per piece. 37 per a piece, not bad ?

Really: it counts hours.