Damping Factor

Altecboy · 2088

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Offline Altecboy

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on: May 04, 2024, 01:44:49 AM
My Monamours drive my Altec Model 19 clones easily.  My drivers are 16 ohms.  I note that the bass is a bit loose.  Will I get more damping if I change from the 16 ohm configuration to say 8 ohms?

thanks for all replies.



Offline Paul Joppa

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Reply #1 on: May 04, 2024, 04:19:10 AM
Yes, you will nearly double the damping factor by using the 8 ohm  output to drive a 16 ohm speaker.

You will also get about 80% as much power, and about half the distortion.

[edited to add] You may also want to experiment with a smaller parafeeed cap, 1/4 to 1/2  the stock value.
« Last Edit: May 04, 2024, 04:27:24 AM by Paul Joppa »

Paul Joppa


Offline Altecboy

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Reply #2 on: May 04, 2024, 10:57:47 PM
thanks Paul.



Offline Altecboy

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Reply #3 on: May 05, 2024, 12:24:24 AM
BTW, is there a spec on the what the damping factor of the Monamour is?
thanks.



Offline Gerry E.

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Reply #4 on: May 05, 2024, 04:59:08 AM
Yes, you will nearly double the damping factor by using the 8 ohm  output to drive a 16 ohm speaker.

You will also get about 80% as much power, and about half the distortion.

Hi PJ:

Do those damping factor, power and distortion figures hold true when running 8-ohm speakers from a 4-ohm tap?  If yes, any other potential downsides, other than the approx. 20% reduction in power, when configured like this?  Thanks!

Gerry     



Offline Paul Joppa

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Reply #5 on: May 05, 2024, 05:45:52 AM
Yes, the effect works the same when driving a 16-ohm speaker from the 8-ohm wiring, or driving an 8 ohm speaker from the 4-ohm wiring, or driving a 4-ohm speaker from the 2-ohm wiring.

These are the main effects. There will be some minor changes in the extreme frequency response of the output transformer. I'd have to run the design calculations to be sure, but in general there will be more extended highs and less extended bass. I doubt either would be audible. The vagaries of speaker impedance in the deepest bass and highest treble are probably bigger than these effects.

Incidentally, many transformers have (slightly) inferior response at the lower impedance taps. That's not the case with the OT-2 or the OT-5 used in the Kaiju and the MonAmour. That's the reason these transformers don't have simple impedance taps but require re-wiring to change the load impedance.

Paul Joppa


Offline Paul Birkeland

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Reply #6 on: May 05, 2024, 06:52:37 AM
BTW, is there a spec on the what the damping factor of the Monamour is?
Without making calculations or measuring one, I would expect the damping factor to be approximately 3.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man