Getting the amplifier damping factor with speaker impedance right is important?

[Analogous]

This from an old post at Audigon: ( adjustable damping factors!)

folkfreak​

05-03-2016 at 04:44am
As the owner of a pair of VTL MB 450 III with adjustable damping factor (4 settings) I can attest to the fact that damping factor matters. Obviously it's an interaction with the rest of your system but as I got my room resonances under control I could lower the DF on my Magico Q3s and now have it at the lowest setting. The effect of lowering DF is to lose some immediate "punch" in the bass but replace it with greater air, scale and overall body which is much more preferable. My suspicion would be that too many amps (especially solid state) are over damped but that's just my preference and I'm surprised more manufacturers don't offer adjustable DF

 

[Kannan]

just to add one more perspective.......i wonder how this damping works with multiway speakers, where the amplifier sees only the crossover which is then connected to multiple speakers through a network and the outputs of the network wired to the individual speakers through additional cables, and these cables are often very thin (though length is short). So in such cases, how is the impedance of the load calculated (i.e the individual speaker impedances and their cables and the network in-between).
The again, some multiway speakers can also be biamped or triamped.......
........just pondering.....

 

[Analogous]

.....just pondering....

Interesting questions…

 

[IndianEars]

just to add one more perspective.......i wonder how this damping works with multiway speakers, where the amplifier sees only the crossover which is then connected to multiple speakers through a network and the outputs of the network wired to the individual speakers through additional cables, and these cables are often very thin (though length is short). So in such cases, how is the impedance of the load calculated (i.e the individual speaker impedances and their cables and the network in-between).
The again, some multiway speakers can also be biamped or triamped.......
........just pondering.....

Damping factor has a substantial effect even with multiway speaker with cover networks, though the effect of DF is max with single driver units.

The Xover connects each driver via a low impedance (as direct a connection as possible) at the frequencies at which that driver is operating.

Further, the LF driver is typically connected to the amplifier with very few components in its path.

The Mid Freq driver has much smaller cone excursions & the tweeter of course has miniscule excursion length, making dampening these drivers less of a concern, anyway.

This from an old post at Audigon: ( adjustable damping factors!)

folkfreak​

05-03-2016 at 04:44am
As the owner of a pair of VTL MB 450 III with adjustable damping factor (4 settings) I can attest to the fact that damping factor matters. Obviously it's an interaction with the rest of your system but as I got my room resonances under control I could lower the DF on my Magico Q3s and now have it at the lowest setting. The effect of lowering DF is to lose some immediate "punch" in the bass but replace it with greater air, scale and overall body which is much more preferable. My suspicion would be that too many amps (especially solid state) are over damped but that's just my preference and I'm surprised more manufacturers don't offer adjustable DF

A Good post on the topic.

Worth mentioning that amplifiers that provide a choice of damping factors, do this by varying the negative (usually overall negative) feedback.

The audible effects observed are also due to the amplifier's other characteristics due to reduced feedback.

So what one hears is not just the effect of reduced Damping Factor, but also reduced negative feedback.

 

[arj]

It has to do with design of drivers. Most vintage drivers manufactured by Altec, Lowther, Tannoy, JBL, etc, are designed in such a way that they prefer amps which don’t exercise much control. Which is why these speakers generally prefer tube amps.

As @IndianEars has also mentioned , what prem has written above is whats key
Start with the speaker drivers and then arrive at the right amp
I presume the kind of material used will also matter a lot eg thin treated paper etc will be very light and hence needs lower damping factors while the thicker materials like kevlar etc will need higher damping

Using a right damping ( usually greater than 100 although 20 is a significan number ) with a light driver will make the sound really tight but bass can be sharp and lacking harmonic richness and hence tiring
While the other end of the spectrum would be loose and thick sound with high colouration /sluggish presentation..

 

[Analogous]

Damping factor has a substantial effect even with multiway speaker with cover networks, though the effect of DF is max with single driver units.

The Xover connects each driver via a low impedance (as direct a connection as possible) at the frequencies at which that driver is operating.

Further, the LF driver is typically connected to the amplifier with very few components in its path.

The Mid Freq driver has much smaller cone excursions & the tweeter of course has miniscule excursion length, making dampening these drivers less of a concern, anyway.

So given all the above it would be very challenging to get all the drivers to work together coherentlly with minimal overlap of frequencies?
would it affect the timing too?

 

[Hari Iyer]

Impedance, and how it affects audio equipment

ESP - The Audio Pages. Impedance - what it is, what it does, and the effects of impedance on loudspeakers, power loss in cables and more.

sound-au.com

 

[prem]

I don’t know the theory behind all of this. Most of my comments are based on personal listening experience. In single and concentric drivers, the effect of damping factor becomes more evident. When I was searching for an amp for a Lowther driver, Nelson Pass suggested I buy his First Watt F3 amp which he said had the perfect damping factor of 8 for a Lowther driver. In his experience an amp with a higher or lower damping factor of 8 didn’t work as well with a Lowther driver.

Even when I was considering one of his amps for my JBL4343, a speaker he was very familiar with, he recommended the INT 60 which has the lowest damping factor among all his Pass Labs amps.

Even when David Berning designed an amp for me, he gave me two damping factor options because he wasn’t sure which one would work better with the Rethms.

So Analogous, since I knew Zu was a concentric driver along the lines of a Tannoy, and since I also knew the designer preferred tube amps with his speakers, I thought a Karan with such a high damping factor is unlikely to get the best from your Zu.

 

[Kannan]

So Analogous, since I knew Zu was a concentric driver along the lines of a Tannoy, and since I also knew the designer preferred tube amps with his speakers, I thought a Karan with such a high damping factor is unlikely to get the best from your Zu.

i was going through Zu recommendations, they too suggest tube amps with minimal feedback or vintage SS from Sansui AU series, Yamaha etc.

 

[arj]

Recently I was considering getting (yet another) amplifier to try with my existing speakers…. So I consulted with an experienced FM (@prem) who has been generous and patient in responding to my queries. He told me there would be a mismatch between the speaker impedance and the Amplifier damping factor.

I was curious to understand this phenomenon as I had not considered this before while selecting components. A brief exploration online I saw this. Hope it’s of use to others too.

https://eaw.com/amplifier-damping-factor-more-is-better-or-is-it/BKK

the Quicksilver amps would be great with that..I use them with my Tannoys. with a Damping of 20 they work excellently.

 

[IndianEars]

A crude DIY quick fix to lower Damping Factor of a High DF amp, is to insert a 1 Ohm 10 Watt resistor in series with the speaker....

Will bring down the Damping Factor to 8.

There will be an approx 12% loss of power ( a 100 Watt amp ... down to 88 Watts approx) but no other negative side effect on the amp.

You can lower or raise the Damping factor to your hearts content by increasing / decreasing the resistor....

Just some lateral thinking & food for thought ....

 

[Hari Iyer]

A crude DIY quick fix to lower Damping Factor of a High DF amp, is to insert a 1 Ohm 10 Watt resistor in series with the speaker....

Will bring down the Damping Factor to 8.

There will be an approx 12% loss of power ( a 100 Watt amp ... down to 88 Watts approx) but no other negative side effect on the amp.

You can lower or raise the Damping factor to your hearts content by increasing / decreasing the resistor....

Just some lateral thinking & food for thought ....

I have tried this method to increase Qts of the woofer for open baffle, but unfortunately the level drop is too much and does not improve ghe SQ meant for intended purpose.

 

[IndianEars]

I agree with you, Hari. However I feel your post is out of context of the discussion here, and could create un necessary apprehension in the minds of those not-so-well-informed.

Since we are discussing Damping Factor alone it Must be pointed out here that your experience of a significant drop in the output of an Open Baffle Woofer, when driven by a lower damping factor amp (in an effort to increase Qts), is normal and predicted. You may find the last post in this thread informative. The post points out that an OB Sub Qts of around 0.23 to 0.28 yielded a 97 tp 99 dB/watt efficiency..... But increasing the Qts to .9 - 1.5 dropped the efficiency by almost 10 dB! ( 89-92 db/watt ).

Clearly, the lost efficiency is a predicted link to the change in Damping Factor. It is Not a system mis-behaviour due to adding an external resistor.

There is really no downside to using a simple series resistor for reducing the effective damping factor of an amp + speaker combo.

 

[Hari Iyer]

In the Basta simulator you can play around with this series resistors and can actually simulate how the SPL changes and how the Qts changes by different values of this series resistor.

 

[Analogous]

I agree with you, Hari. However I feel your post is out of context of the discussion here, and could create un necessary apprehension in the minds of those not-so-well-informed.

Since we are discussing Damping Factor alone it Must be pointed out here that your experience of a significant drop in the output of an Open Baffle Woofer, when driven by a lower damping factor amp (in an effort to increase Qts), is normal and predicted. You may find the last post in this thread informative. The post points out that an OB Sub Qts of around 0.23 to 0.28 yielded a 97 tp 99 dB/watt efficiency..... But increasing the Qts to .9 - 1.5 dropped the efficiency by almost 10 dB! ( 89-92 db/watt ).

Clearly, the lost efficiency is a predicted link to the change in Damping Factor. It is Not a system mis-behaviour due to adding an external resistor.

There is really no downside to using a simple series resistor for reducing the effective damping factor of an amp + speaker combo.

These series of resistors would be in line (connected between the speaker cable and speakers?

 

[IndianEars]

These series of resistors would be in line (connected between the speaker cable and speakers?

Yes, 1 resistor per channel, in series ... Can be mounted at the speaker between the cable & the speaker termination ( either +ve or -ve termination, any one)

Or

. Can be mounted at the amplifier, between the cable & the amplifier termination ( either +ve or -ve termination, any one).

You don't need a very fancy non inductive resistor, just a regular wirewound resistor (cost less than Rs 10 each).

Can play around with the value, there is no danger to the amp or speakers, for ANY resistor value you may use.

 

[sachinchavan 15865]

A crude DIY quick fix to lower Damping Factor of a High DF amp, is to insert a 1 Ohm 10 Watt resistor in series with the speaker....

Any DIY fix to achieve the opposite - increase the damping factor of an amp? Or say, lower the impedance of the signal route starting from from the amp’s outlet? I’d think choice and contact of the connectors and cable could be one. What else?

 

[Analogous]

Yes, 1 resistor per channel, in series ... Can be mounted at the speaker between the cable & the speaker termination ( either +ve or -ve termination, any one)

Or

. Can be mounted at the amplifier, between the cable & the amplifier termination ( either +ve or -ve termination, any one).

You don't need a very fancy non inductive resistor, just a regular wirewound resistor (cost less than Rs 10 each).

Can play around with the value, there is no danger to the amp or speakers, for ANY resistor value you may use.

This is super helpful. Thank.
now to decide which speaker cable to cut (+ or -). They are factory terminated with banana plugs
You have also mentioned “

Can be mounted at the amplifier, between the cable & the amplifier termination ( either +ve or -ve termination, any one).

is there a good way of doing this?

 

[IndianEars]

Sadly, Not much that you can do to Improve Damping Factor of the system, besides what you have mentioned/. If you are using Mono blocks, then you can locate them very close to & behind the speakers. Even these changes will yield only small changes to the System Damping factor, which the damping factor of the amplifier itself will remain unchanged.....

It is almost never easy to improve a system, "deteriorating" its specification is much easier.

Improving the Damping factor requires design level changes like changing the bias of the output devices or adding overall negative feedback.

 

[Analogous]

Sadly, Not much that you can do to Improve Damping Factor of the system, besides what you have mentioned/. If you are using Mono blocks, then you can locate them very close to & behind the speakers. Even these changes will yield only small changes to the System Damping factor, which the damping factor of the amplifier itself will remain unchanged.....

It is almost never easy to improve a system, "deteriorating" its specification is much easier.

Improving the Damping factor requires design level changes like changing the bias of the output devices or adding overall negative feedback.

In that case I will wait for a braver FM to try and report on th audible effects of adding resistors in series.
There are definitely rare occasional benefits of following the herd.