Eico HF60 mono block amplifier bias and balance adjustment help wanted.

mcgarick

Super Member
Hello!
Just as the title says, I'm looking to find out how to properly adjust the bias and use the balance adjustment for these new to me, tube mono block amplifies. The manual is online, but I cant make heads or tales what the bias instructions are saying..
That said, I'm not a circuit guru type, but I have a meter and a willingness to learn.
If anyone would want to lend a hand, I would appreciate it.

https://www.manualslib.com/manual/887304/Eico-Hf-60.html

Thanks!
 
According to the manual, insert the probes of your meter into the meter jacks, and adjust the balance control for "0" volts, and after that, insert the + lead in one of the jacks, and connect the - lead to a screw on the chassis, and adjust the bias adjustment for .65v it is not important which jack you use.
After adjusting recheck the balance, and if readjusted, readjust the bias again
 
Awesome! Thank you Scott. Some people say these amps run the el34 a little to hard. If I used .55v would that be going the right way to lighten up on them?

Also, for the balance adj. do I use the meter probes the same as bias? Negative on the metal of the unit, and one in the meter hole slot on the side of the unit?

I wonder why they put two meter holes on the side if only one is used.





Thanks again.
 
Last edited:
Ok, I re-read what you had said for balance, to use both probe spots.


Awesome! Thank you Scott. Some people say these amps run the el34 a little to hard. If I used .55v would that be going the right way to lighten up on them?

Also, for the balance adj. do I use the meter probes the same as bias? Negative on the metal of the unit, and one in the meter hole slot on the side of the unit?

I wonder why they put two meter holes on the side if only one is used.





Thanks again.
 
Yes to both questions, running them a little lighter would save the tubes, there may be a small increase in distortion, but it will not likely be noticeable
 
Looks like plate+screen dissipation is 30.5 watts on a tube rated for 33 watts plate+screen. Backing that down some will not be bad for the tubes. Worth looking at the other voltages in there too, they are likely to be high with higher than 1960s line voltage.
 
I checked my amps and you steered me right. The volts were at .46 per tube. Amps sound terrific BTW
Thanks again.
 
Back
Top Bottom