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Damping factor

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Posted on January 26, 2025 at 20:10:25
elflow
Audiophile

Posts: 358
Location: Indiana
Joined: November 1, 2005
 When two identical mono tube power amps have their outputs wired in parallel, what effect does this have on the damping factor, ie does the damping factor double or remain the same? Thanks.

 

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In order to do this, posted on January 27, 2025 at 13:16:28
Ralph
Manufacturer

Posts: 5068
Location: Minnesota
Joined: April 24, 2002
 The amps must be identical and the same signal present at both inputs.

This will double the damping factor if feedback is employed. For proper matching, for an 8 Ohm speaker you would use the 16 Ohm taps.

You cannot do this with a solid state amp- they have to be bridged instead of mono-strapped else damage will occur.

 

True damping factory or the marketing one?, posted on January 27, 2025 at 15:52:58
Victor Khomenko
Manufacturer

Posts: 57229
Joined: April 5, 2000
 The true one will most likely not change much at all.

The marketing one will double... if that means anything.


 

With solid state amps it depends on topology, posted on January 27, 2025 at 15:56:15
Victor Khomenko
Manufacturer

Posts: 57229
Joined: April 5, 2000
 We parallel them all the time.


 

RE: In order to do this, posted on January 27, 2025 at 21:31:03
elflow
Audiophile

Posts: 358
Location: Indiana
Joined: November 1, 2005



Thank you for conformation, I have been using two rebuilt(Jim McShane parts) operating as mono bloc amps each driving a JBL Sovereign speaker, for many years.

 

RE: In order to do this, posted on January 28, 2025 at 06:32:27
Tre'
Industry Professional

Posts: 17896
Location: So. Cal.
Joined: February 9, 2002
 Cit 1, 2, 3 and a Empire 598? Nice!

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

+1 sweet! nt, posted on January 28, 2025 at 08:52:41
Ralph
Manufacturer

Posts: 5068
Location: Minnesota
Joined: April 24, 2002
 -

 

Don't encourage that!, posted on January 28, 2025 at 09:15:19
Ralph
Manufacturer

Posts: 5068
Location: Minnesota
Joined: April 24, 2002
 I'm sure you're aware that most solid state amps won't survive that sort of treatment.

 

We should not be making blanket statements, posted on January 28, 2025 at 11:21:22
Victor Khomenko
Manufacturer

Posts: 57229
Joined: April 5, 2000
 Some tube amps will blow up with such connection, some solid state models will run happily.

Like I said - depends on topology.


 

That's true- I'd be interested to know what tube amps? nt, posted on January 28, 2025 at 12:29:37
Ralph
Manufacturer

Posts: 5068
Location: Minnesota
Joined: April 24, 2002
 -

 

RE: In order to do this, posted on January 29, 2025 at 19:18:22
elflow
Audiophile

Posts: 358
Location: Indiana
Joined: November 1, 2005
 I am over fifty years behind time and very happy to be there!

 

Empire mods, posted on January 31, 2025 at 12:21:47
Ralph
Manufacturer

Posts: 5068
Location: Minnesota
Joined: April 24, 2002
 The Empire responds very well to mechanical damping. You'll hear the result of damping the platter right away.

I used the model 208 since it was easier to install a modern arm. I kept working on damping it and finally had a plinth machined of solid aluminum but otherwise allowed the Empire parts to be mounted. The platter was heavily damped. All these changes affected the sound of the turntable, in particular the bass impact.

 

Related: Solid State amps can "smoke" when driving a Transformer., posted on February 19, 2025 at 09:58:08
VoltSecond
Manufacturer

Posts: 2541
Location: Arizona
Joined: October 14, 2000
 Very true, two Solid State amps wired in parallel "CAN" be high risk.

I've had an amp with a "DC coupled output" smoke when an impedance matching transformer was hooked up to it. The DC offset from the amp caused a moderate DC current to flow in the transformer and thus also flow through the amp's output stage. This DC current made the amp hotter. The hotter amp's DC offset got larger thus making the amp get even hotter and eventually "Poof", a dead amplifier. In this case, the solution was to put a very large non-polar cap in series with transformer.

Two "DC coupled output" amps wired in parallel can have a similar risk. If the outputs had different "DC offsets" or different voltage gains, one amp will drive power into the other amps that is lost as heat.

There are solid state amps "made" to be used in parallel. These amps won't have this issue.

Moral of the story: Know thy circuit and carry a big soldering iron. ;-}


Play safe and play longer! Don't be an "OUCH!" casualty.
Unplug it, discharge it and measure it (twice) before you touch it.

. . .Oh!. . .Remember: Modifying things voids their warranty.

 

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