Hammond in SSE

[Pilsern]

I will use Hammond transformers in my SSE and I have acquired the 374BX power transformer but not yet decided on output transformers.

What would be the "best" Hammond output transformer for my SSE - 1629SE, 1628SEA.... other ?

I am planning to use KT88 tubes in the amp.

Thanks in advance,

[boywonder]

Have a look at the "tubes & transformers" tables at Tubelab's website. Specifically the table for KT88.

Here is the link:

Tubes & Transformers

The Load Z column is the output transformer primary impedance; the table gives you power out, distortion, tube power dissipation etc based on a given B+ voltage and current. The tube dissipation numbers in red are exceeding the dissipation rating of the tubes........if you like to push the envelope a little, these values will probably work although it somewhat varies depending on how robust your KT88's are.

[Pilsern]

Originally Posted by boywonder

Have a look at the "tubes & transformers" tables at Tubelab's website. Specifically the table for KT88.

Here is the link:

Tubes & Transformers

The Load Z column is the output transformer primary impedance; the table gives you power out, distortion, tube power dissipation etc based on a given B+ voltage and current. The tube dissipation numbers in red are exceeding the dissipation rating of the tubes........if you like to push the envelope a little, these values will probably work although it somewhat varies depending on how robust your KT88's are.

Thanks,
So if I have understood the "tubes & transformers" tables right a Hammond 1627ESE (3K prim. imp.) will be the best option if I want to get the most power out of the KT88's ?

[boywonder]

Originally Posted by Pilsern

Thanks,
So if I have understood the "tubes & transformers" tables right a Hammond 1627ESE (3K prim. imp.) will be the best option if I want to get the most power out of the KT88's ?

Correct. 3K with a 500V B+ and an idle current around 70-80ma gets the most power out without going overboard on the tube dissipation. Higher tube dissipation=shorter life.

Typical primary Z for KT88's is 3K-4K ohms.

A couple of things to keep in mind......a 500V B+ may push the voltage rating of 500V rated PS caps at start-up. Maybe not too bad with a slow warm up 5AR4 vac regulator. With solid state rectification, it's highly likely that the cap voltage rating will be exceeded at start up (most low ESR 500V rated electrolytics are rated for 550V surge).

One watt one way or the other won't make that much audible difference. As a general rule-of-thumb, using a higher primary impedance output transformer will yield less power out and less distortion than a lower impedance.

[rmyauck]

5K primary is pretty popular as you get a good balance of power and lower distortion. I read where George likes that primary impedance himself .

Randy