Steel String Singer 150w Transformers

[kutless84]

Does anyone have any leads where to find a power transformer for 150w KT88 SSS build? If not, what specs I should send to a transformer company?

Thank you!
Jay K.

[WhopperPlate]

Hammond makes a 290s2z sunn 2000 replacement transformer . 780 vct @ 400ma HT. 8amp heater current . -55 bias tap 5v 4amp tap. Those amps were conservatively rated at 120w clean. If I recall correctly 4x6550 sss have been measured around 135w clean output. Someone else who knows better should be able to chime in and confirm or deny

[kutless84]

That’ll definitely get me in the ballpark! Thank you!!

[Roe]

Output transformer should be 2k2, with a good frequency reponse like a dynaco a451

[didit]

Hello --

Another solid (perhaps better) option from the Hammond catalog is the 378CX; with slightly higher secondary, bunch more current, and no winding wasted on 5V rectifier.

..

[Colossal]

Output transformer should be 2k2, with a good frequency reponse like a dynaco a451

I had Heyboer wind one for me for a bass amp. Sounded fantastic. It was nearly 11kg!

[didit]

Output transformer should be 2k2, with a good frequency reponse like a dynaco a451

I had Heyboer wind one for me for a bass amp. Sounded fantastic. It was nearly 11kg!

Did they "can" it for you like the Dynaco originals?

..

[Colossal]

Output transformer should be 2k2, with a good frequency reponse like a dynaco a451

I had Heyboer wind one for me for a bass amp. Sounded fantastic. It was nearly 11kg!

Did they "can" it for you like the Dynaco originals?

..

No, but I didn't ask them to. It was a massive transformer, as was the power transformer that went along with the build. The PT was also close to 11kg.

[kutless84]

I had Heyboer wind one for me for a bass amp. Sounded fantastic. It was nearly 11kg!

Did they "can" it for you like the Dynaco originals?

..

No, but I didn't ask them to. It was a massive transformer, as was the power transformer that went along with the build. The PT was also close to 11kg.

Were the specs the same as the Dynaco?

Also, thank you all for the suggestions and input! Greatly appreciated!

[WhopperPlate]

Hello --

Another solid (perhaps better) option from the Hammond catalog is the 378CX; with slightly higher secondary, bunch more current, and no winding wasted on 5V rectifier.

..

Nice . Bias winding is only 6A instead of 8A…probably works fine still , we all know 183 Twin PT can handle the extra cutrent draw from EL34….conservative ratings

[didit]

Hello --

Another solid (perhaps better) option from the Hammond catalog is the 378CX; with slightly higher secondary, bunch more current, and no winding wasted on 5V rectifier.

..

Nice . Bias winding is only 6A instead of 8A…probably works fine still , we all know 183 Twin PT can handle the extra cutrent draw from EL34….conservative ratings

Filament and yes, it's a bit less than desirable, but likely cool regardless due to Hammond's rating over spec. As spec'ed a touch overloaded and nothing really left for preamp and PI assuming a quad of larger KT series heaters. Suggest KT77 would work well, or 6CA7EH; both are pretty robust. A few minutes doing some sums are in order before putting out any purchase orders.

..

[WhopperPlate]

Hello --

Another solid (perhaps better) option from the Hammond catalog is the 378CX; with slightly higher secondary, bunch more current, and no winding wasted on 5V rectifier.

..

Nice . Bias winding is only 6A instead of 8A…probably works fine still , we all know 183 Twin PT can handle the extra cutrent draw from EL34….conservative ratings

Filament and yes, it's a bit less than desirable, but likely cool regardless due to Hammond's rating over spec. As spec'ed a touch overloaded and nothing really left for preamp and PI assuming a quad of larger KT series heaters. Suggest KT77 would work well, or 6CA7EH; both are pretty robust. A few minutes doing some sums are in order before putting out any purchase orders.

..

Precisely, meant to say filament , thanks for correcting

[Roe]

How about this PT: https://www.tube-town.net/ttstore/en/to ... h100r.html

Pri: 230 V (blau-rot/blue-red)
Sec 1: 330 V @ 0,5 A (rot-rot / red-red)
Sec 2: 15 V @ 1,5 A (weiss-schwarz / white - black)
Sec 3: 15 V @ 1,5 A ( schwarz - weiss ( black - white)
Sec 4: 3,4 V @ 9 A ( blau - grau / blue - grey)
Sec 5: 3,4 V @ 9,0 A (grau - blau / grey - blue)
Sec 6: 100 V @ 0,01 A (orange - orange)

330+15+15VAC=360VAC

This should give 500VDC at idle (my experience with another of their PTs in this series is that unloaded voltages read higher than the spec'ed nominal voltages. 330VAC gives me 460VDC+ at idle (with a 75ma current draw roughly)