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December 12, 2019, 06:46:58 PM

Author Topic: Balanced outputs for Stereomour?  (Read 1390 times)

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Offline Jim R.

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Balanced outputs for Stereomour?
« on: November 06, 2011, 05:44:42 AM »
I just re-read this thread:

http://www.bottlehead.com/smf/index.php/topic,2227.0.html

And have to wonder if the Stereomour OPTs can also be configured for balanced output?  Any downside to this arrangement if it is possible?  Especially thinking of any issues with connecting a sub amp to speaker level inputs.

Dan, also wondering if you've tried the paramounts in balanced config with speakers yet?  I'm assuming that with getting the Smack manual done, that you haven't, but thought I'd ask anyway.

Thanks,

Jim
« Last Edit: November 06, 2011, 08:46:43 AM by jrebman »
Jim Rebman -- recovering audiophile

Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).

s.e.x. 2.1 under construction.  Want list: Stereomour II

All ICs homemade (speaker and power next)

Offline Doc B.

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Re: Balanced Balanced outputs for Stereomour?
« Reply #1 on: November 06, 2011, 06:19:52 AM »
Hey Jim,

I was indeed cranking on the Smack manual exclusively last week. Just about done, should have wrapped it up tomorrow. However Shawn had some time in his schedule after the Smack build to finish up a pair of Paramounts that are part of our long term project to get the reference system back up to the 18 amps it was designed around. We have been running a shunt regulated 45 amp on each of the 96 dB ribbons, a pair of Paramounts wired in parallel on each 90 dB midrange and a single Paramount on each channel's four woofer, 96 dB series parallel wired array. Though the sensitivity numbers may suggest otherwise, the new pair of amps was subjectively deemed most needed on the woofer array. So Shawn rewired the Paramount OTs of the now four woofer amps for 4 ohms and created a "virtual center tap" using 60 ohm resistors from each end of the secondary to ground (rather than the stock arrangement of connecting the cold leg of the OT secondary to ground). The speakers are wired in parallel pairs for a 4 ohm load.

The result from listening briefly is better (punchier and deeper) bass. However, too many other things changed at once - speaker wiring configuration and max power level along with the center tap setup - to be able to say with certainty that the balanced configuration was solely responsible for it. It is however a pretty easy thing to try and I would encourage others to try it and report your results. Remember, it doesn't seem to make any sense, and it may just all be in my head.

Regarding Stereomour, yes, the neat little switching board that PJ designed for Smack OTs should work with the Stereomour (and S.E.X.) too and allow for balanced output (nope, hole spacing is too small to mount the board under the Paramount trans). That is one of several kit upgrade products we are trying to get done in the next few weeks, along with S.E.X. 2.1 C4S, S.E.X. 1.0 OT-2 upgrade, Otari MX-5050 tape path upgrade, and maybe a couple others.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline Jim R.

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Re: Balanced outputs for Stereomour?
« Reply #2 on: November 06, 2011, 08:52:28 AM »
Dan,

Sounds good, and I'll be keeping an eye on the iron upgrade for the s.e.x. 20 as well.

-- Jim
Jim Rebman -- recovering audiophile

Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).

s.e.x. 2.1 under construction.  Want list: Stereomour II

All ICs homemade (speaker and power next)