A few more DIY Tube amp Questions

Discussion in 'DIY' started by H713, Feb 12, 2018.

  1. H713

    H713 New Member

    After a bit of pondering after my last post, I've got two designs in mind. I'd prefer not to spend the $250 on a pair of ST-70 output transformers. I'd like to keep the output transformers under 200. I'm trying to decide between building an "ST-70" with Edcor transformers (probably have to be a 5k or 6.6K) or building this design, also with Edcor transformers:

    Alternatively, I could scrap the EL34/6L6 idea, buy a pair of ST-35 transformers and build a 6BQ5 amp. I'd really prefer the extra power of the EL34, but I'd be open to that idea if it would sound significantly better. My speakers are 87db efficiency if I remember, so I think a 17W amp would be pretty small.

    Unrelated, anyone know the power transformer or B+ voltages in a Conrad Johnson PV10?

    Thanks guys, I'm still a little new to this. Sorry if this post is a bit redundant to my last thread.


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  2. Shadowdog

    Shadowdog Super Member

    Flin Flon, Manitoba
    ST-35 used the Z-565 transformers which are said to be better than the ST-70 transformers by many and the ST-70 are better than Edcors PP from lots of reading. It's about the interleaving when winding a transformer and the ST-35's Z-565 has the most, which improves the high & low frequencies along with lower distortion. It takes more time to do it properly so the cost is higher for the ST-70 verse the lower priced Edcor ones.

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