Bias reading = dc offset?

rockdrummer · 376

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Offline rockdrummer

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on: July 04, 2024, 05:06:33 AM
Hi everyone.  I’ve done some searching and not finding this exact topic.  I’m running a dvd player as a source, into a Moreplay into a Stereomour 1. Everything is stock, and I have servo subs and planar two-ways (91db at 8ohms) on stands from GR Research. The stereomour is volume up while I control with the preamp.

I have a bad right tweeter, and already replaced a bad tweeter on the same channel a couple years ago because it didn’t work from the beginning. Drivers came up bad pretty often in those early batches.

A couple days ago, I had the rig running, maybe 2 minutes, then upped the volume to about 60% which is actually higher than I ever listen. Right tweeter started cutting in and out during that song, then nothing. I posted on the GR forum knowing about tweeter issues but the replacement I got has been working quite a while now.

All I can do is follow directions so I don’t know much about down-and-dirty details about electronics.

——Does checking the stereomour bias equal dc offset of a solid state amp?

——Second rookie question, does bias change even though I haven’t changed tubes?

——Third rookie question, does higher volume raise chances of damaging drivers and are tweeters first to go? My mid planar drivers work fine.

Thanks for reading.
Ben
« Last Edit: July 04, 2024, 05:20:13 AM by rockdrummer »



Offline Doc B.

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Reply #1 on: July 04, 2024, 06:16:19 AM
Stereomour is a cathode bias circuit. It adjusts itself. It is also a parallel feed transformer output circuit. Not only is the transformer output secondary isolated from DC, the cap coupled primary is as well. So there is no DC voltage offset at the output of a properly constructed and functioning amp. You could of course verify this by measuring DC volts across the output of the amp.

You would probably get better info from the tweeter manufacturer than from us regarding its reliability and power handling. The stereomour only puts out about 3 or 4 watts max.if you are running it hard into clipping it might put out a bit more.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline Paul Birkeland

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Reply #2 on: July 04, 2024, 08:54:27 AM
A couple days ago, I had the rig running, maybe 2 minutes, then upped the volume to about 60% which is actually higher than I ever listen. Right tweeter started cutting in and out during that song, then nothing.
I would be looking really hard at both the crossover design for what you're using and what's actually built into the crossover.  This could easily be something like a cap value that's off or some kind of crossover error that just isn't all that obvious when you listen but is enough to cause damage to the tweeter.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man