Quality of Hammond 1600 series transformers and a question about loading.

[G]

Hi all. I was wondering if anyone has had any experience with the "improved" versions of the Hammond 1600 series output transformers. Has their quality control improved? I know that a few years ago there were complaints about mismatched performance between any two transformers when spectrum analysis was done. They unfortunately do not give you the DCR specs on their site so can I use the formula I squared R to figure out the DRC or will that not work in this case?

Also I wanted to ask about the ratio of load to a given plate resistance on a SE power stage. Is four times the plate resistance acceptable?

[Brett]

Look at the WE 300B data, esp graphs 2 and 3 and you'll get an idea of distortion and power trends for SE triodes. You can extrapololate the trends loosely to other triodes.
http://www.westernelectric.com/produ...0b_graphs.html

For a more exact answer, you need to specify the tune and op point. 2x Ra gives most power. 4x will gives less power but less distortion.

Tubecad, Steve Bench and Patrick Turner (www.turneraudio.com.au - educational and DIY section) all have explanations of loadlines on their sites. Turner is especially good for power tubes and Tubedacd Grounded Cathode primer is the best I've read. MJ's Valve Amplifiers is well worth the money if you want to learn about tubes, and especially how to apply that step by step into a finished design.

[kstagger]

I have a pair of 1627SEA OTs that I will be using for a SE EL156 amp - I'll let you know how they turn out (if I ever get a chance to finish that project!).