Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: pbman1953 on April 11, 2026, 03:38:13 pm

Title: Amp getting a new OT- 4 & 8 ohm-what happens with the Negative Feedback wire?
Post by: pbman1953 on April 11, 2026, 03:38:13 pm

I'm taking out the old 4 Ohm OT and installing a new OT with 4 & 8 ohm. What happens with the negative feed back wire?


Thanks

Title: Re: Amp getting a new OT- 4 & 8 ohm-what happens with the Negative Feedback wire?
Post by: sluckey on April 11, 2026, 03:44:36 pm

Connect it to the 4Ω tap

Title: Re: Amp getting a new OT- 4 & 8 ohm-what happens with the Negative Feedback wire?
Post by: pbman1953 on April 11, 2026, 03:54:35 pm

Thank you!


 

Title: Re: Amp getting a new OT- 4 & 8 ohm-what happens with the Negative Feedback wire?
Post by: pbman1953 on April 11, 2026, 05:22:45 pm

I did a soft connect . Only ran wires to the same spots. After turning it on there's wasn't a howl so I suppose the wire were in their proper places but the sound is un-clear/ fuzzy.

Title: Re: Amp getting a new OT- 4 & 8 ohm-what happens with the Negative Feedback wire?
Post by: Esquirefreak on April 12, 2026, 01:45:44 am

What's a soft connect?

Title: Re: Amp getting a new OT- 4 & 8 ohm-what happens with the Negative Feedback wire?
Post by: pbman1953 on April 12, 2026, 05:08:35 am

. Leaving the wires long before the permanent connection

Title: Re: Amp getting a new OT- 4 & 8 ohm-what happens with the Negative Feedback wire?
Post by: sluckey on April 12, 2026, 05:43:10 am

Why did you replace the OT? Did the amp sound un-clear/ fuzzy before you replaced the OT? Does this amp have a name? Schematic? Have you done any troubleshooting? Measured any voltages? Give us some background. So far you have offered zero clues for us to guess on.

Title: Re: Amp getting a new OT- 4 & 8 ohm-what happens with the Negative Feedback wire?
Post by: pbman1953 on April 12, 2026, 07:32:24 am

ok, sorry for lack of detail , I thought this was a simple one because its been done before.

Reason for replacement - I have both 4 & 8 ohm cabs- versitility

Sound before - was fine , no issues

Amp Fender Super Twin

Voltages taken - not yet- what is first to test?

In the meantime , until I hear back, I'll look over anything to be sure there are not any bad connections

Title: Re: Amp getting a new OT- 4 & 8 ohm-what happens with the Negative Feedback wire?
Post by: sluckey on April 12, 2026, 07:54:24 am

Put the original OT back in the amp. If sound is fine, then the replacement OT was either incompatible or faulty or connected wrong. Give us the details on the replacement OT.

Title: Re: Amp getting a new OT- 4 & 8 ohm-what happens with the Negative Feedback wire?
Post by: pbman1953 on April 12, 2026, 07:56:33 am

ok, I'll do that


The new one is a Heyboer Fender 012413
-HTS 5251

Title: Re: Amp getting a new OT- 4 & 8 ohm-what happens with the Negative Feedback wire?
Post by: pbman1953 on April 12, 2026, 08:52:37 am

I found it. When I removed the main speaker jack and the extension jack I didn't reground it back to the 33k is was connected to

Title: Re: Amp getting a new OT- 4 & 8 ohm-what happens with the Negative Feedback wire?
Post by: pbman1953 on April 13, 2026, 08:33:02 am

The amp is all set and thanks for the help!