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Author Topic: Stereomour Output Transformers  (Read 1609 times)

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Offline M42

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Stereomour Output Transformers
« on: December 26, 2013, 06:05:24 AM »
Hi All,


I'm seeking some advice as to how I should wire the output transformers on my Stereomour. I was under the assumption that if you were using 8 ohm speakers, the transformers should be wired accordingly. I had read a previous post which seemed to indicate this was not necessarily the case. I can't seem to find that post to refer back to, but it seemed to indicate if you were using 8 ohm speakers and wired for 4 ohms you would sacrifice some volume (gain??) for a lower noise floor. I was wondering what the general consensus might be on this subject. I'm using NST Super Zero speakers until such time as I get my Orcas.

Kind regards,

Jeff
Jeff Hullin

Stereomour(2A3), Eros, Crack/Speedball, Thorens TD160 MKII, Grace F9E, Sennheiser HD600's, Frugelhorn 3's, DIY 8" Subs.

If at first, the idea is not absurd, then there is no hope for it.

Offline fullheadofnothing

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Re: Stereomour Output Transformers
« Reply #1 on: December 26, 2013, 06:41:05 AM »
Wire them for 4Ω. 8Ω is a nominal impedance, most speakers have dips well below their nominal (and, in your case, your manufacturer is actually nice enough to list a minimum of 5.5Ω).
Joshua Harris

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Offline Paul Joppa

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Re: Stereomour Output Transformers
« Reply #2 on: December 26, 2013, 08:23:51 AM »
for broader guidance, I'd say that matching the X ohm wiring to an X ohm speaker provides optimum power transfer. But SET amps have a very broad optimum, and there are other considerations beyond just power. Using the lower impedance wiring improves the damping factor for example, as well as reducing gain, peak power and noise voltage. Experimenting is always the most accurate test in any specific situation.
Paul Joppa

Offline M42

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Re: Stereomour Output Transformers
« Reply #3 on: December 27, 2013, 03:01:28 AM »
Hi Josh and Paul,

Thanks for your advice, I've re-wired the transformers to 4 ohms.

Regards,

Jeff
Jeff Hullin

Stereomour(2A3), Eros, Crack/Speedball, Thorens TD160 MKII, Grace F9E, Sennheiser HD600's, Frugelhorn 3's, DIY 8" Subs.

If at first, the idea is not absurd, then there is no hope for it.

Offline Moot

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Re: Stereomour Output Transformers
« Reply #4 on: December 30, 2013, 04:39:46 PM »
M42 - do you hear any difference now that you're wired for 4 Ohms?

Offline M42

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Re: Stereomour Output Transformers
« Reply #5 on: December 31, 2013, 02:15:19 PM »
Hi Moot,

I wish I could answer your question...I'm still waiting for my replacement power transformer to arrive. I've only completed the mechanical assembly of the kit in the meantime. I decided to work ahead in the manual and had read the comments of others regarding wiring options for the output transformers. I asked the question and have deferred to the advice of the very knowledgeable folks here on the forum. It's not likely that if /when I get the amp up and running I'd risk trying to rewire it for eight ohms.That said, if I muster up the nerve I'll post my impressions of the change.

Regards,

Jeff
Jeff Hullin

Stereomour(2A3), Eros, Crack/Speedball, Thorens TD160 MKII, Grace F9E, Sennheiser HD600's, Frugelhorn 3's, DIY 8" Subs.

If at first, the idea is not absurd, then there is no hope for it.