Bottlehead Forum

Bottlehead Kits => Legacy Kit Products => Stereomour => Topic started by: astroimage2002 on February 21, 2011, 12:33:09 PM

Title: Output transformer secondary configuration Question
Post by: astroimage2002 on February 21, 2011, 12:33:09 PM

Hi All,

Probably a dumb question... I have a new (to me) set of Zu Omen's on the way to me. The impedance of the Zu's is 12 Ohms and they are 98dB. The Stereomour can be set to 2/4/8/16. Where should I set it? I am using the Stereomour with a pair of 6 ohm / 86db speakers and it is working GREAT. The Harbeth's are louder than I can stand... Looking forward to the 12dB gain on the speakers.

Don't know if it matters but I would like to mention that the Stereomour is set up to take 45 tubes and I currently have 2a3's in it.

Any thoughts/ideas/suggestions????

Brian
 

Title: Re: Output transformer secondary configuration Question
Post by: Jim R. on February 21, 2011, 12:48:52 PM

Bryan,

If it were me, I'd try both 8 and 16 ohm configurations and see which is best.  I don't know these speakers, so don't know if they need any help in the bottom end or not, in which case I'd probably start with the 16 ohm setting, but so much depends on so many other factors, obviously including your room and personal tastes, that it would be impossible to guess which will be best.

HTH,

Jim

Title: Re: Output transformer secondary configuration Question
Post by: astroimage2002 on February 21, 2011, 12:52:53 PM

Jim

Thank you for sharing your thoughts! Impedence has the most effect on the bottom end?

Title: Re: Output transformer secondary configuration Question
Post by: Jim R. on February 21, 2011, 01:07:50 PM

Brian,

Not necessarily, just that running a speaker with a lower impedance than the tap generally results in a bit more power, but at the cost of more distortion, and that's usually experienced in the bass, though it sounds like at the levels you listen, it may not be an issue, especially if you are running 2a3s in the 45 configuration on harbeths.

Of course the opposite is also true, that running them on the 8 ohm tap would be slightly less power, but less distortion, and for the same reasoning above, maybe that would work better for you.

Without being there to hear the setup, as I said, it's difficult to make a real recommendation.

-- Jim

Title: Re: Output transformer secondary configuration Question
Post by: Paul Joppa on February 21, 2011, 03:29:30 PM

Jim pretty well nailed the situation.

Incidentally it IS possible to wire the output transformer for 12 ohms. Jumper 1 to 2, taking the positive output from 3 and the negative from 7.

Title: Re: Output transformer secondary configuration Question
Post by: astroimage2002 on February 26, 2011, 06:57:25 AM

Hi Paul,

Thank you for the information. Can the transformer be set up for 6ohms?

Brian

Title: Re: Output transformer secondary configuration Question
Post by: Paul Joppa on February 26, 2011, 07:02:23 AM

Unfortunately no, it cannot be set up for 6 ohms.