Damping Factor

[rantan]

First of all, I definitely know what damping factor is and how it works, but what is of interest to me is why different amplifiers have a high number and others quite low.

 

Are there particular advantages in a high factor and why do some amplifiers have 20-30 times more than another?

 

What is the ultimate aim when the designer decides on a particular number? Is high better than low and what are the respective consequences.?

 

I once heard an amplifier with a hugely high damping factor and it seemed to squeeze the life from the music but is this a one off or poor design or does it depend on the topography of the amplifier?

 

Thanks in advances for your insights.

 

Edit: fixed typo

Edited March 14, 2023 by rantan

[Keith_W]

The damping factor is the ratio between the output impedance of the amplifier and the nominal input impedance of the loudspeaker. In reality, the input impedance of the loudspeaker varies wildly with frequency response and voice coil heating. A high damping factor means that the amplifier has more control over the speaker cones, especially with woofers or subs because those are high mass drivers which require a bit of power to overcome its inertia and momentum. A good example are valve amps which typically have high output impedance, which means low damping factor, which in turn contributes to tubby bass and "warm" sound (which may be due to continued oscillations of the midrange driver). 

 

I am not sure what you mean by "squeezing the life out of music". If you mean low top end frequency response, or poor dynamics, those could be accounted by other design choices. 

[georgehifi]

58 minutes ago, rantan said:

Damping factor: but what is of interest to me is why different amplifiers have a high number and others quite low.

 

 

That "can be" global feedback v local feedback.

"Global feedback" can reduce the output impedance= (hi damping factor),  the same amp if it only has "local feedback" will have higher output impedance = (lower damping factor).

Don't get too carried away with very low output impedance being great for tight controlled bass. There are other parameters also that contribute to having explosive fast punchy control low tight bass, and that's continuous current drive ability into low impedances where most speakers have their worst impedances. 

EG: Look at all ME amplifiers, especially the bigger ones 750 850 1400 1500 I doubt there's an amp anywhere that can show a candle to these bass masters, and they only use "local feedback"!!! and their output impedance is nothing to write home about compared to many. It's their continuous current drive ability into low impedances that make them the bass master.

 

Cheers George  

[Hydrology]

My Hegel (as all their models do) have an absurdly high damping factor and I would never class them as "squeezing the life out of the music" what so ever. In comparison, my old Luxman Class A L550AX sounded lazy and lethargic in comparison when driving the same loudspeakers (and Luxman make bloody great amplifiers!) . In addition to the damping factor, the Hegels are very neutral so they show up more of the sonic flavour of the speaker and other ancillary components in the chain.

But as @Keith_W mentioned, there are other factors at play in everyone's system and one specific "feature" or bullet point of a product, such as damping factor, does not a great amplifier make.

[Jakeyb77_Redux]

My Holton amp that @tubularbells kindly made for me has great damping factor which I chose to pump the big 15” woofers on the JBL 4435 

 

Damping Factor At 100hz 8Ω = 1300

[LogicprObe]

3 hours ago, Keith_W said:

The damping factor is the ratio between the output impedance of the amplifier and the nominal input impedance of the loudspeaker. In reality, the input impedance of the loudspeaker varies wildly with frequency response and voice coil heating. A high damping factor means that the amplifier has more control over the speaker cones, especially with woofers or subs because those are high mass drivers which require a bit of power to overcome its inertia and momentum. A good example are valve amps which typically have high output impedance, which means low damping factor, which in turn contributes to tubby bass and "warm" sound (which may be due to continued oscillations of the midrange driver). 

 

I am not sure what you mean by "squeezing the life out of music". If you mean low top end frequency response, or poor dynamics, those could be accounted by other design choices. 

 

Yes...........I always thought that the damping factor was a measured thing at a certain frequency that made no sense at all.

In my opinion, it was only a thing in single driver, valve amps and it just carried over into solid state stuff.

More important is the power transfer function but as KW has stated frequency plays  a big part and crossover phase relationship possibly even more.

 

These days.........I reckon it's a load of dung.

(Although ,I do have a lot of old valve radios that I love)

[Keith_W]

BTW, conventional wisdom has it that a damping factor of 10 is sufficient for most amp-speaker systems. However, John Siau from Benchmark argues that a DF of 200 is more desirable. Read the article here. 

[LogicprObe]

3 minutes ago, Keith_W said:

BTW, conventional wisdom has it that a damping factor of 10 is sufficient for most amp-speaker systems. However, John Siau from Benchmark argues that a DF of 200 is more desirable. Read the article here. 

 

This is why I always prefer sealed to ported enclosures as well, Keith.

[March Audio]

Damping factor beyond a certain level (I'm not defining what level) becomes a little moot as the current flowing in the circuit is fundamentally limited by the much larger driver impedance.

 

There shouldn't be any issues with having a very high factor though.

Edited March 14, 2023 by March Audio

[rantan]

17 hours ago, Keith_W said:

I am not sure what you mean by "squeezing the life out of music". If you mean low top end frequency response, or poor dynamics, those could be accounted by other design choices. 

 

This is certainly what I experienced when I had the .......... amplifier in my system. The dynamics seemed to be constrained and the overall feeling was one lacking in timbre a tone and musicality , but as you correctly point out this could have many contributing factors

16 hours ago, Hydrology said:

comparison, my old Luxman Class A L550AX sounded lazy and lethargic in comparison when driving the same loudspeakers

As many people here would know, I have had a Luxman L550A II for about 6 years and lazy and lethargic are descriptors which I have never experienced from it and are so wide of the mark that it is almost comic, but this is just my opinion and is ,by no means, definitive.

 

To be honest I am not aware of the damping factor of my Luxman ( yes I know I could ask Dr Google ) but whatever the figure may be it seems exactly right and my joyous years of listening to it with a wide variety of speakers are proof enough for my purposes.

I also would like to thank everybody for their responses. It is appreciated and I hope there may be many more.

 

Cheers to all.

[georgehifi]

41 minutes ago, rantan said:

typo

typo

Edited March 15, 2023 by georgehifi

[rantan]

@georgehifi

 

Sorry man but that quote is not mine, although I did use the "squeezing the life out of the music" in a different context in my OP

[georgehifi]

On 14/03/2023 at 6:29 PM, Keith_W said:

I am not sure what you mean by "squeezing the life out of music"

Not sure who quoted it to make Keith ask.

Means "Compressing" to me

"If you have no quite bits you have no loud bits" It called dynamic range as you know, and it gives the music calm/breadth/depth and startle factor when the dynamics hit.

 

Squeezing/compressing makes it all sound a bit too much like Phil Spectors "Wall of Sound" recordings, where just about everything is compressed to the same dB level. That way you don't miss out on the low level stuff if there's background noise. That's why he said he evaluated all his recordings on the cars system driving around with all the background noise!!!!

This is NO good for the quiet of the man cave with a good red a mega system. That's also why you almost never see classical music compressed, you don't want the little triangle to be as loud as guy with the big crashing cymbals.

 

Cheers George

Edited March 16, 2023 by georgehifi

[Hydrology]

15 minutes ago, rantan said:

 

 

As many people here would know, I have had a Luxman L550A II for about 6 years and lazy and lethargic are descriptors which I have never experienced from it and are so wide of the mark that it is almost comic, but this is just my opinion and is ,by no means, definitive.

 

As just as many people would know I owned a 550AX MKI for almost the same time period. The keywords that need to be highlighted in my original post, which I used more than once in the same sentence was "in comparison to". This comment I made in NO WAY undermines the incredible performance of Luxman amplifiers.

It's why in my daytime job I try to take a very holistic approach to a clients questions, rather than just "I need a new amplifier, what can you sell me?". System synergy is very important for me to get right.

Ironically, had the situation been the reverse and I owned a Hegel first, I most likely wouldve replaced it with the Luxman for its wonderfully smooth, relaxed, organic signature! Such is the journey of a hifi enthusiast.

[rantan]

6 minutes ago, Hydrology said:

As just as many people would know I owned a 550AX MKI for almost the same time period. The keywords that need to be highlighted in my original post, which I used more than once in the same sentence was "in comparison to". This comment I made in NO WAY undermines the incredible performance of Luxman amplifiers.

 

It is all good and no issues mate. I know what your intent was and I always respect your opinion/s

 

I also did not intend to make this into any type of brand naming ,which is also why I did not and will not name the amplifier I described in my OP. My only intent was to better understand why damping factor varies so much and what its purpose may be.

 

Cheers.

[Hydrology]

1 minute ago, rantan said:

 

It is all good and no issues mate. I know what your intent was and I always respect your opinion/s

 

No probs mate its all constructive conversation - I still love ya!!!

 

But you are right, I love both low damping factor amps and absurdly high damping factor amps in equal amounts.

I guess for me its just about what my ears like.

[Keith_W]

1 hour ago, rantan said:

This is certainly what I experienced when I had the .......... amplifier in my system. The dynamics seemed to be constrained and the overall feeling was one lacking in timbre a tone and musicality , but as you correctly point out this could have many contributing factors

 

 

Well, one way to get a low output impedance is to increase global negative feedback. This reduces the gain of the amplifier, which might make the amp compress or clip when driven hard. If your amp has such a design it is possible that these two could be related. 

[rantan]

Just finished doing some research on my amplifier and the one which I alluded to in the OP.  "X" amplifier damping factor= >1000. Luxman =  200.

 

Given the considerable difference between the two, I wonder what the subjective and objective differences there would be in the same system, in the same room, level matched, with no other changes in equipment or cables?

[MLXXX]

7 minutes ago, rantan said:

Just finished doing some research on my amplifier and the one which I alluded to in the OP.  "X" amplifier damping factor= >1000. Luxman =  200.

 

Given the considerable difference between the two, I wonder what the subjective and objective differences there would be in the same system, in the same room, level matched, with no other changes in equipment or cables?

none

 

[barely measurable objectively, and no difference subjectively]

Edited March 15, 2023 by MLXXX

[rantan]

3 minutes ago, MLXXX said:

none

OK, fair enough, and I appreciate your definitive answer, but why was my reaction so very different in each case?

 

*******Please note, I have absolutely NO desire or intent to engage in a debate about all amplifiers sounding the same ,nor do I seek posts regarding sighted listening.********

My intent is to find why they had such a differing presentation of the music played at the time.

[Hydrology]

11 minutes ago, rantan said:

OK, fair enough, and I appreciate your definitive answer, but why was my reaction so very different in each case?

 

*******Please note, I have absolutely NO desire or intent to engage in a debate about all amplifiers sounding the same ,nor do I seek posts regarding sighted listening.********

My intent is to find why they had such a differing presentation of the music played at the time.

Amplifier topology, amplifier design, component/semiconducter choices, synergy with partnering equipment etc etc and I think we can still throw expectation bias in the mix too.

[rantan]

I should also mention that there were two other people with me at the time of auditioning and we all noted the differing presentations of both amps. I would like to think that I had no expectation bias at all and the other two people most certainly did not.

[MLXXX]

1 minute ago, rantan said:

I should also mention that there were two other people with me at the time of auditioning and we all noted the differing presentations of both amps. I would like to think that I had no expectation bias at all and the other two people most certainly did not.

 

You appear to have decided to focus on a particular amplifier spec.  And you appear to have decided it was responsible for the differences in sound you heard.

 

If amplifiers differ (and they tend to differ only slightly these days) it could be for any number of reasons.   I would look beyond "damping factor".

[Hydrology]

7 minutes ago, rantan said:

I should also mention that there were two other people with me at the time of auditioning and we all noted the differing presentations of both amps. I would like to think that I had no expectation bias at all and the other two people most certainly did not.

I think it re-enforces the idea of "try before you buy" (where possible) or at the very least listen before you buy.

There are plenty of members who do their research and buy products unheard  - some of them very happy with their decision, some not. Some of those users have more disposable income than others, so trying something unheard, not liking it and moving it on at a loss is no big deal. For some of us, we hate the idea of making a bad decision that will cost us money.

I have no problem with those who listen to products and despite the hype, don't like them. That's cool. What gets on my goat are those who believe the numbers tell us everything we need to know about how a product will perform, and based on performance, how it will sound.

Despite my personal and professional affiliation with Hegel, I found them not a great match for Wilson Audio (every model I've heard except the new pre/power) despite the specification of say, the H590, being more than cable driving a pair of Sabrina X. As I aspire to own a pair of Sasha DAW at some point, I simply know Hegel wont be part of that long-term goal for my personal system.

[Keith_W]

If you read that article I linked to earlier by John Siau, he makes a convincing argument that a damping factor > 200 is of marginal benefit. 

As for why those two amplifiers sounded different, who knows. Without knowing more about the two amps you were comparing, it is impossible to say. 

And yes, I get what you mean about people who think amps sound the same. I am engaged in a debate on another forum where someone had done a DBT and found that amps sound different (10/10 correct). It's almost like a religion among some folks who do not believe that an amp, when measured under artificial conditions, could work differently when subjected to real world conditions. 

Edited March 15, 2023 by Keith_W