Hello all
interesting thing happened today.
Decided to replace the speaker terminals with banana jacks on my Mark 3's
Amp one- all replaced , powered up and suddenly I had gain up the wazoo.
Amp 2 - all replaced, powered up and all I got was distorted sound.

When I replaced the terminal strip, I eliminated the #7 connection to
the 16 ohm tap. I removed the 680 ohm resistor from common to the 16 ohm
tap. And left the 16 ohm floating free.

Amp one had no problem with these removed. Amp 2 could not handle the load?

I connected the 16 ohm tap to wire #7, installed the 680 ohm resistor
but left the tap unconnected.

Gain dropped back to normal for amp 1. Amp 2 no longer has distortion.
Could some one explain why one worked and one did not


Thank you in advance
Mike M

You disconnected the global feedback.

--
Alan Gallacher
Born to Tinker!

"mike m" wrote in message
ink.net...
Hello all
interesting thing happened today.
Decided to replace the speaker terminals with banana jacks on my Mark 3's
Amp one- all replaced , powered up and suddenly I had gain up the wazoo.
Amp 2 - all replaced, powered up and all I got was distorted sound.

When I replaced the terminal strip, I eliminated the #7 connection to the
16 ohm tap. I removed the 680 ohm resistor from common to the 16 ohm tap.
And left the 16 ohm floating free.

Amp one had no problem with these removed. Amp 2 could not handle the
load?

I connected the 16 ohm tap to wire #7, installed the 680 ohm resistor but
left the tap unconnected.

Gain dropped back to normal for amp 1. Amp 2 no longer has distortion.
Could some one explain why one worked and one did not


Thank you in advance
Mike M

Hello all
interesting thing happened today.
Decided to replace the speaker terminals with banana jacks on my Mark 3's
Amp one- all replaced , powered up and suddenly I had gain up the wazoo.
Amp 2 - all replaced, powered up and all I got was distorted sound.
When I replaced the terminal strip, I eliminated the #7 connection to
the 16 ohm tap. I removed the 680 ohm resistor from common to the 16 ohm
tap. And left the 16 ohm floating free.
Amp one had no problem with these removed. Amp 2 could not handle the
load?
I connected the 16 ohm tap to wire #7, installed the 680 ohm resistor
but left the tap unconnected.
Gain dropped back to normal for amp 1. Amp 2 no longer has distortion.
Could some one explain why one worked and one did not
Thank you in advance
Mike M

Hello Mike,
First, when you removed the tap from the 16 ohm line, you disconnected the
global feedback (that's where it's taken from). Naturally gain will increase
with no feedback, but so will distortion. You have feedback to reduce
distortion. I sure that explains one amp. As to the other amp, you can rest
assured that your recount of the facts are not right (happens to all of us).
What you experience will happen to any non-modified Dynaco MK III. Hope this
helps you and please be careful with those exposed high voltages.
Cordially,
west

Thank you to both of you for your answers. Its explains alot.
After 7 years of rebuilding amps, I've decided to try my hand at
modifing and than finally on to building my own. So I guess I'm a
neewbie at this next phase.
Thank you
Mike M