[boroson]

I am wiring up an Ultimate 70 on an amp I tore apart 15 yrs ago. In wiring the output transformers with a single pair of output jacks, I intend to use the 8ohm leads (orange). Should I connect the wire from connection #8 to the left orange (speaker +) and #11 to the right? Or do these wires only connect to the 16ohm (yellow) lead?

[boroson]

Thanks for the help.

[Tom Alverson]

Keep the connections to 8 and 11 on the 16 ohm taps.  Connecting them to the 8 ohm taps will change the feedback and increase the gain of the amp a little.

[avahifi]

Sorry for the delay in answering, hugely busy around here right now.

Anyway,  output transformer wiring:

Yellow is 16 ohm tap
Orange is 8 ohm tap
Brown is 4 ohm tap
Black is ground.

The feedback wires must always be connected from eyelets 8 and 11 on the audio board to the 16 ohm taps (yellow), whether or not these are being used.

If you are only wiring in a single output tap, the unused taps need to be connected to isolated from ground and eachother terminal strips installed inside the chassis near the output jacks and the feedback wires then must be connect to the 16 ohm taps, isolated from ground.

I hope this helps.

Regards,

Frank Van Alstine

[boroson]

I got the amp fired up and adjusted the bias to 1.48v across a 15ohm resistor since I did not have a 15.6. The amp is stable, however the output is very low in both channels.

My output trans wires were very short and faded. I am using one set of output jacks. I used the orange wires for the speaker + then changed to the brown to see if this solved the problem and it did not. Where should I look for a problem. (Bad output xfmrs?) .

Thanks
Bryan Oroson

[avahifi]

Make sure the feedback wires to the circuit board are attached to the Yellow (16 ohm) taps.

If the output is identically low in both channels, then the issue is probably not an output transformer, as that would affect one channel only unless both transformers had identical faults (highly unlikely).

The issue may very well be an assembly error.  Parts swapped, wrong value parts in some places, etc.  The only way we can provide further help is if you ship the amp here for us to test, evaluate, and repair.  Call us first before doing that.  651-330-9871

Frank Van Alstine