|
Vintage Asylum Classic gear from yesteryear; vintage audio standing the test of time. |
|
|
|
Vintage Asylum Classic gear from yesteryear; vintage audio standing the test of time. |
|
In Reply to: RE: Trusty McShaned Eico HF87 posted by elflow on August 15, 2016 at 09:46:15:
Keep in mind that the cathode biased HF87 makes as much or more power than the Dynaco ST70 with fixed bias..This is because the HF87 is running a higher B+ potential, between the plate and cathode of the output tubes.You then have a far superior driver/phase-splitter,and voltage amp,then the 7199 offers.You have two sections of the 6SN7 in each channel along with the voltage gain of the 12AX7. Once the McShane upgrades are done,this amp takes off and flies around the room.I have never gotten the dynamics,depth,or bottom end in an ST70,that I have gotten out of HF87 even with cathode bias.Even the iron as you say,is so much better in the HF87.
What the fixed bias will do is give me more power because now you will have full plate voltage running across the output tubes.I will also be able to run KT88s,KT66s,and 6L6gcs as well..
The original cathode bias resistor was 235 ohms at 10 watts..The other side was a 165 ohm in series with the 12AX7 filament to make up the bias resistnce on the other side.I used a 250 ohm on both sides and then put 6.3vac on the filament of the 12AX7 between 4,5,and 9.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
Edits: 08/15/16 08/15/16
This post is made possible by the generous support of people like you and our sponsors:
Follow Ups
- RE: Trusty McShaned Eico HF87 - Michael Samra 14:00:56 08/15/16 (0)
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2024, Audio Asylum, all rights reserved ]
