ARC SP-6 Warmup time

I owned a couple different versions of this preamp. The 6B and later did have a "timer mute" circuit, but I remember it only took a minute or two at most to unmute. It was a long time ago,so maybe I've forgotten.

Here is an excerpt from a 6B owner's manual:

http://www.arcdb.ws/SP6/ARC_SP6B_flyer4.jpg

The SP-6C-1 was my favorite, followed by the 6E.

Nope, it's not normal. I would recommend calling Audio Research. It sounds like you will be sending it in for repair. I hope you didn't pay too much for it. This is why a 9/10 rating on these older units is not accurate. The faceplate may be free of scratches, however, the electronics is 30 years old and failing. Also, if you want your preamp restored to original and sound the way it's supposed do not send it to anyone except Audio Research. It may cost a little more, but it is well worth it.

The mute time should not be more then 3.25 minutes. After that the LED should glow bright and the signal should be un-muted. If this is a B, or C version its usually caused by a leaky capacitor in the timer circuit and or a bad opto-coupler. If the unit hasn't been in for service, now would be a good time to do it. The B/C versions has multiple regulated supplies. A bad cap in any of them could cause a domino effect and take out the other regulators.

The '6B and later versions mute for one minute upon turnon.
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I own a modded 6-B which never took more than a minute or so. When I first glanced at the topic, I thought No the tone of my ARC 6-B was always on the colder, analytic side, and couldn't be warmed up by my usual tube rolls LOL!