• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

S5 K-12G output trans

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I wasn't sure exactly what the primary impedance should be , but knew the 8K of the dynaco Z-565 would be close. Best to use change to fixed bias with 8K if they were used. Dave Gillespie's EFB mod (for fixed bias) would be a really low cost ($10) way to go and should give you a bit more power and improved sonics.

If you can swing the $ with the Edcors get the CXPP series for even greater bandwidth, as you will notice it especially bass and it will help the highs.

EDCOR - CXPP30-MS-10K

Randy
 
If you can swing the $ with the Edcors get the CXPP series for even greater bandwidth, as you will notice it especially bass and it will help the highs.

EDCOR - CXPP30-MS-10K

Randy

+1, Well worth spending as much as you can afford on OT's. IMHO this is where you get most sonic improvement for your dollar. Ultra linear taps give you another option to play with.

If you've been bitten by the bug and want to build something of greater power and quality then the 8k version might be the better option to go for. This would allow you to build an EL84 based amp. Lots of good designs available on this forum.
 
You can use 10K for EL84's with Cathode bias which might be better suited to. Heathkit used it on their AA-151 and others which used the same Output Transformers. Dave Gillespie mentioned this on his EFB (Enhanced fixed Bias) mod on the Tranola web site.

You will loose a bit of power , but you will gain less distortion with the higher primary impedance anyway.

Just some thoughts.

Regards,

Randy
 
I built the K502, a kit similar to the K12G from S5 and using 11BM8 tubes. I upgraded the OT'S using the Hammond 1609 (10k). Very pleased with the increase in sound quality. My next project was Gingertubes' Baby Huey using EL84's. The 1609's were removed from the K502 and did sterling service in the Baby Huey despite their 10W rating. Another happy step up in sound quality, the sort that requires a person to listen to their entire music collection all over again. :)

All the same though I wouldn't mind hearing the 30W Edcors

Regards Bill
 
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