View Full Version : Carver amp and Damping factor.....what gives???


djnagle
09-02-2011, 08:44 PM
I have a blown Carver TFM45 amp and I can get it refirbed for $200. Before I do that, I started reading about the damping factor of any amp. What it means to the sound, what is an acceptable factor.....that kind of stuff. In many places, I read that the minimum damping factor for an amp is 50 but it is better to have it up into the 150 to 200 range.

So then I look at the Carver TFM45 lit. and see that amp has a damping factor of 7!!!

I don't really know about damping factor and can only tell you what I've read, but "7" seems pretty low.

Any thoughts or opinions???

Celt
09-02-2011, 08:47 PM
Damping factor is something I pay attention to when looking at amplifier specs. Very low damping factors usually means poor control of the woofer.
I prefer amps with a damping factor of 100 or greater, but 50 is acceptable. However, IMO 7 is not.

whoaru99
09-02-2011, 08:48 PM
I have a blown Carver TFM45 amp and I can get it refirbed for $200. Before I do that, I started reading about the damping factor of any amp. What it means to the sound, what is an acceptable factor.....that kind of stuff. In many places, I read that the minimum damping factor for an amp is 50 but it is better to have it up into the 150 to 200 range.

So then I look at the Carver TFM45 lit. and see that amp has a damping factor of 7!!!

I don't really know about damping factor and can only tell you what I've read, but "7" seems pretty low.

Any thoughts or opinions???

Yeah, I'd say it probably puts it right in there with some tube amps. Afaik, the unit was voiced with The Carver Silver Seven in mind, from what I've read.

Myself, I don't know the DF of my tube amp, but my ARC 100.2 has a rated DF of 20 and there is no problem with loose bass or anything like that. If pressed hard, I might even go out on a limb and opine it's the best-sounding amp I have.

djnagle
09-02-2011, 08:55 PM
Thanks. I will only be driving my woofers with this amp (or maybe not this amp) so maybe I should be looking elsewhere for an amp with a higher damping factor. I really don't have the $$$ to get it fixed only to find out that it is not what I want.

A friend of mine also tri amps and runs his woofs with a SS amp. We've A/B SS amps and tube amps on his woofs and the SS just sounds tighter than the tubes but I never understood why.

Jon_Logan
09-02-2011, 09:00 PM
Does that model amp have a "Current" output and a "Voltage" output?

Carver liked to offer that "Current" output to make solid state amplifiers sound more like tube amps. If it does have this current output, a series resistor in the output would lower the amp's intrinsic damping number.

egisjohn
09-02-2011, 10:53 PM
I dont know about the damping factor. But I run a tfm-42 (same as the 45 but with led,s) on my infinity rs-1b woofer towers. 6 8" woofers per side. all I can say is it rocks!!!!!!!

bshorey
09-02-2011, 10:58 PM
I dont know about the damping factor. But I run a tfm-42 (same as the 45 but with led,s) on my infinity rs-1b woofer towers. 6 8" woofers per side. all I can say is it rocks!!!!!!!

What he said. I'm running mine now with my Ohm F's, and it sounds just fine. I've also used it with Magnepan MGIIIa's and Ohm I's, both sounded fine to my ears.

For $200 to repair, if you find it's not to your liking you can probably sell it for more than that.

bs

Tedrick
09-03-2011, 12:48 AM
I have a blown Carver TFM45 amp and I can get it refirbed for $200. Before I do that, I started reading about the damping factor of any amp. What it means to the sound, what is an acceptable factor.....that kind of stuff. In many places, I read that the minimum damping factor for an amp is 50 but it is better to have it up into the 150 to 200 range.

So then I look at the Carver TFM45 lit. and see that amp has a damping factor of 7!!!

I don't really know about damping factor and can only tell you what I've read, but "7" seems pretty low.

Any thoughts or opinions???
This would explain why the TFM-25 I used to have did not sound very good with my Infinity RS-IIIb's. The amp just could not take control of the woofers, and the result was bass that was flabby, muddy, ill-defined, and lacked extension. It may have worked just fine with less-demanding speakers, but I don't have the Carver anymore :no:.

whoaru99
09-03-2011, 12:58 AM
Here's an interesting read on damping factor...at least I think so.

http://www.audioholics.com/education/amplifier-technology/damping-factor-effects-on-system-response

egisjohn
09-03-2011, 01:24 AM
This would explain why the TFM-25 I used to have did not sound very good with my Infinity RS-IIIb's. The amp just could not take control of the woofers, and the result was bass that was flabby, muddy, ill-defined, and lacked extension. It may have worked just fine with less-demanding speakers, but I don't have the Carver anymore :no:.

less dimanding than rs1-b? my 42 is a house thumper. bi amped elect x over. will never part with it. just my .02

motorstereo
09-03-2011, 05:40 AM
I keep my tfm45 as a backup to my Mc 2500. The 2500 is also a low df amp but neither amp has any shortcomings from low df. I have multiple drivers in my polk sda's and lots of guys say you need a high df amp to control all those woofers. Once I had the 45 hooked to the sda's though I put the importance of high df in the circular file. Same thing with the Mc2500; it controls all those woofers just fine with a low df and lets the bass through as well.

Celt
09-03-2011, 08:20 AM
Some speaker systems are such as to where the DF won't be as critical. The ones I own will easily embarrass an amp with low damping factors, making the system sound loose and flabby in the bass regions. Sorry, it's an important consideration for me.

Uncle Paul
09-03-2011, 11:54 AM
Thanks. I will only be driving my woofers with this amp (or maybe not this amp) so maybe I should be looking elsewhere for an amp with a higher damping factor. I really don't have the $$$ to get it fixed only to find out that it is not what I want.

I'd say to get it fixed, and if it doesn't meet your needs then sell it. TFM-45's are pretty desirable and easy to sell.

Now, if you want something with a high DF that can bitch slap those woofers around all day see if you can find a BGW. These are sonically very nice as well. BGW's fly nicely under the radar and can be had pretty inexpensively.

JonVH
09-03-2011, 11:58 AM
Take a woofer and quickly strike the diaphragm to set it in motion. The primary resonance will be at it's Fs and some harmonics and will sustain for several milliseconds.

Now, short the driver's wires and strike the woofer diaphragm. It comes to a stop pretty quick.

That's what a high effective damping factor does. Not every speaker will need a high damping though.

Dr Tinear
09-03-2011, 12:24 PM
I have a blown Carver TFM45 amp and I can get it refirbed for $200. Before I do that, I started reading about the damping factor of any amp. What it means to the sound, what is an acceptable factor.....that kind of stuff. In many places, I read that the minimum damping factor for an amp is 50 but it is better to have it up into the 150 to 200 range.

So then I look at the Carver TFM45 lit. and see that amp has a damping factor of 7!!!

I don't really know about damping factor and can only tell you what I've read, but "7" seems pretty low.

Any thoughts or opinions???

The TFM in the model number stands for Transfer Function Modification. Bob Carver voiced the amp to sound like a tube amp, and part of the voicing involved giving the amp a high output impedance (= low damping factor). The low DF is therefore a deliberate design choice.

bshorey
09-03-2011, 01:21 PM
Here's an interesting read on damping factor...at least I think so.

http://www.audioholics.com/education/amplifier-technology/damping-factor-effects-on-system-response

I've been spending a lot of time on that site since you posted the link previously. Lots of interesting reading there. Thanks!

bs

hwirt
09-03-2011, 02:40 PM
Here is an interesting paper on the dampening factor debate; it explains the issue without getting too technical. In the summary it draws some conclusions from the calculations and measurements:

http://www.lansingheritage.org/images/jbl/reference/technical/damping-factor/page01.jpg

http://www.lansingheritage.org/images/jbl/reference/technical/damping-factor/page02.jpg

Frank Sol
09-03-2011, 03:26 PM
Huge Damping Factor & Dynamic Headroom specs look good on paper and probably help sales. I should know... the Damping Factor on my 5500 is listed as 700 :)

Pete B
09-12-2011, 11:40 PM
The TFM in the model number stands for Transfer Function Modification. Bob Carver voiced the amp to sound like a tube amp, and part of the voicing involved giving the amp a high output impedance (= low damping factor). The low DF is therefore a deliberate design choice.

Right, and the TFM amps were the result of the "Carver Challenge" to Stereophile where he essentially won, matching the sound of the boutique tube amp that they chose for him to match:
http://carvermk2.com/Docs/Carver%20Stereophile%20Challenge.pdf


Regarding damping factor:
http://www.diyspeakers.net/Articles/Richard%20Pierce%20DAMPING%20FACTOR.pdf

qsaudio
09-13-2011, 01:05 AM
I think it has to do with Carver using the power as it needs it, controlled by tracking the signal telling the AC power to turn on more or less via a triac in the power supply.

Make sure you have a good AC outlet good new wiring from the breaker box.

Other amps use a full supply all the time, so maybe they rate it that way, but is not comparing using the same way of operation compared to conventional power supplies.

So in effect, cone control is based on how hard the amp is running, the more you turn it up, the more the amp gets power.

and that is why I don't really like when amp brands mess around feeding the amp section with variable power supplies

It should still sound good though, and my take on it may be wrong, my own theory.

whoaru99
09-13-2011, 11:05 PM
Damping factor is just a calculation based on the nominal speaker impedance divided by the output impedance of the amp. Resistance of speaker cable adds to the amp side of the equation and lowers the calculated/published damping factor. It's nothing terribly mysterious.

RichP714
11-20-2011, 09:04 PM
Here's an interesting read on damping factor...at least I think so.

http://www.audioholics.com/education/amplifier-technology/damping-factor-effects-on-system-response

That's a good article, and covers most of the salient points. Another good source of info is at: http://www.thecarversite.com/yetanotherforum/default.aspx?g=posts&m=23237#post23237

Damping is a spec that can be easily manipulated through the feedback loop to any value desired; as the above articles demonstrate, it's practically meaningless for consumer wire lengths to the speaker.

Ken Boyd
12-11-2011, 04:29 PM
I was always curious as to how amps from tube amps, autoformers with their low damping factors could control the bass drivers from souding boomy or muddy. I noticed a damping factor of 10 on the big Sansui BA 5000 amp which also uses autoformers. From a few other articles I read some people prefer the loose bass response from a very low damping factor even though that article refered it as lack of bass control, or distortion. That warm sound of tubes was they way the presented it. Either way this was an interesting thread, as it got me to checking all the damping factors on my amps and most all of them were at greater than 1000. I guess I don't have that warm sound of tubes. But that one old printed post makes it seem that by the time you add the speaker your damping factor has increased. The other article went into much more detail involving speakers feedback of EMT's which was much harder to understand for me. But it was written by Crown which sells pro audio amps for big bass drivers used in pro audio.

mhardy6647
12-11-2011, 04:55 PM
The Augspurger reprint above is excellent.

whoaru99
12-11-2011, 05:50 PM
I was always curious as to how amps from tube amps, autoformers with their low damping factors could control the bass drivers from souding boomy or muddy. I noticed a damping factor of 10 on the big Sansui BA 5000 amp which also uses autoformers. From a few other articles I read some people prefer the loose bass response from a very low damping factor even though that article refered it as lack of bass control, or distortion. That warm sound of tubes was they way the presented it. Either way this was an interesting thread, as it got me to checking all the damping factors on my amps and most all of them were at greater than 1000. I guess I don't have that warm sound of tubes. But that one old printed post makes it seem that by the time you add the speaker your damping factor has increased. The other article went into much more detail involving speakers feedback of EMT's which was much harder to understand for me. But it was written by Crown which sells pro audio amps for big bass drivers used in pro audio.


That's because it's an old wives tale about damping factor controlling the bass. Mythbuster's....BUSTED.

Published DF is at the amp's speaker terminals not figuring cable resistance. Everything from there makes published DF decrease, there is no increase beyond the published number. Your DF 1000 amps are probably DF 100-200 with speakers connected. Just the way it works...

Ken Boyd
12-11-2011, 06:45 PM
That's because it's an old wives tale about damping factor controlling the bass. Mythbuster's....BUSTED.

Published DF is at the amp's speaker terminals not figuring cable resistance. Everything from there makes published DF decrease, there is no increase beyond the published number. Your DF 1000 amps are probably DF 100-200 with speakers connected. Just the way it works...

That's funny that is exactly opposite of what I understood from the article. If that was the case then a tube amp or an amp like with an autoformers DF would only be DF 1/2 or less. In another article I was reading most people could not hear a noticeable difference in distortion due to lack of bass driver control until it reached about a DF of about 7. The article below stated that low DF on an amp didn't take into consideration of the resistance of the loudspeaker and when you include the loudspeakers resistance the DF was increased making a low DF amp not a problem because in theory with the increased resistance of the speaker and the wire to the speaker the DF would be higher than what the DF was at the amps output terminals.

TerryO
12-11-2011, 08:55 PM
That's funny that is exactly opposite of what I understood from the article. If that was the case then a tube amp or an amp like with an autoformers DF would only be DF 1/2 or less. In another article I was reading most people could not hear a noticeable difference in distortion due to lack of bass driver control until it reached about a DF of about 7. The article below stated that low DF on an amp didn't take into consideration of the resistance of the loudspeaker and when you include the loudspeakers resistance the DF was increased making a low DF amp not a problem because in theory with the increased resistance of the speaker and the wire to the speaker the DF would be higher than what the DF was at the amps output terminals.

Ken,

Regardless of how important you think DF is, your last sentence is clearly and completely erroneous.

Best Regards,
TerryO

Ken Boyd
12-11-2011, 09:54 PM
I guess i must have misunderstood the way they were trying to use the combination of the speaker and the wire to increase the resistance would somehow make a low DF amp higher in actual real DF. I guess than that the two resistances added together would then actually decrease the DF? I just was reading an several more articles regarding this and it seems that some claim that lower than 20 can be a problem with some speakers, and at the resonance point of a speaker is where a high DF could really be needed. That article basically downplayed any need for a high DF other than perhaps a very low DF or at resonace, and then claimed that the only real way to control a bass driver is by using a servo. I guess in reality it doesn't really matter to me, I was just trying to learn a bit more about all this kind of stuff. There was one article published by Crown audio which seemed to really stress the inportance of a high DF.

whoaru99
12-11-2011, 10:47 PM
That's funny that is exactly opposite of what I understood from the article. If that was the case then a tube amp or an amp like with an autoformers DF would only be DF 1/2 or less.

No, any given amount of speaker lead resistance factors more heavily against high DF than against lower DF. Sorta like the old proverbial saying, the higher you fly the farther you fall.

For example, 6ft of 12ga speaker wire takes DF 1000 down to 290, but same wire changes DF 50 to 44, and DF 20 changes only 1 point to DF 19.

Gibsonian
12-11-2011, 11:43 PM
For sure, Crown company clearly considers damping factor important, as they have for many years advertised the high df of their amplifiers.

goldear
12-11-2011, 11:57 PM
That particular amp was deliberately DESIGNED to have a low damping factor since it was designed to sound very much like a Carver Silver 7. ALL tube amps have low damping factors, and this accounts for one of the differences between tube and SS sound.

Usually a high damping factor only truly indicates that your amp has gobs and gobs of negative feedback anyways (which is not always such a great thing). Yes this can make a slight difference in the bass with very demanding speakers. But most of the time the resistance in your speaker cables is enough to render the DF essentially meaninlgess anyways.

But if you feel that you must have a high damping factor, then don't buy one of the Carver's models which was designed to sound like a tube amp.

whoaru99
12-12-2011, 12:07 AM
For sure, Crown company clearly considers damping factor important, as they have for many years advertised the high df of their amplifiers.

Everyone plays up what they sell.

TerryO
12-12-2011, 02:20 AM
That particular amp was deliberately DESIGNED to have a low damping factor since it was designed to sound very much like a Carver Silver 7. ALL tube amps have low damping factors, and this accounts for one of the differences between tube and SS sound.

Usually a high damping factor only truly indicates that your amp has gobs and gobs of negative feedback anyways (which is not always such a great thing). Yes this can make a slight difference in the bass with very demanding speakers. But most of the time the resistance in your speaker cables is enough to render the DF essentially meaninlgess anyways.

But if you feel that you must have a high damping factor, then don't buy one of the Carver's models which was designed to sound like a tube amp.

Speaker cables certainly dump the Damping. :D

TerryO
12-12-2011, 02:30 AM
That particular amp was deliberately DESIGNED to have a low damping factor since it was designed to sound very much like a Carver Silver 7. ALL tube amps have low damping factors, and this accounts for one of the differences between tube and SS sound.

Usually a high damping factor only truly indicates that your amp has gobs and gobs of negative feedback anyways (which is not always such a great thing). Yes this can make a slight difference in the bass with very demanding speakers. But most of the time the resistance in your speaker cables is enough to render the DF essentially meaninlgess anyways.

But if you feel that you must have a high damping factor, then don't buy one of the Carver's models which was designed to sound like a tube amp.

That's the logical answer.

Nelson Pass doesn't seem to worry about it very much. His commercial amps have pretty low DF, and his latest First Watt amps are very low. Mc Intosh amps have, AFAIK, never had a very high Damping Factor and I don't recall anyone finding fault with their amplifier's bass output.

Best Regards,
Terry

mhardy6647
12-12-2011, 10:13 AM
That particular amp was deliberately DESIGNED to have a low damping factor since it was designed to sound very much like a Carver Silver 7. ALL tube amps have low damping factors, and this accounts for one of the differences between tube and SS sound.

Usually a high damping factor only truly indicates that your amp has gobs and gobs of negative feedback anyways (which is not always such a great thing). Yes this can make a slight difference in the bass with very demanding speakers. But most of the time the resistance in your speaker cables is enough to render the DF essentially meaninlgess anyways.

But if you feel that you must have a high damping factor, then don't buy one of the Carver's models which was designed to sound like a tube amp.
Couldn't have said it any better myself :-)
(although, FWIW, the part about vacuum tube amps' sound that I really enjoy has nothing to do with LF performance...)

That's the logical answer.

Nelson Pass doesn't seem to worry about it very much. His commercial amps have pretty low DF, and his latest First Watt amps are very low. Mc Intosh amps have, AFAIK, never had a very high Damping Factor and I don't recall anyone finding fault with their amplifier's bass output.

Best Regards,
Terry
The autoformer-coupled SS Macs certainly have modest damping factors - dunno about the direct-coupled ones.

To me, the fixation on DF is tantamount to basing decisions on which car to buy by focusing on the maximum tire pressure ratings printed on the little tag on the drivers' door frame... it's not exactly inconsequential, but there's far more to the story in terms of understanding how the car performs.

Ken Boyd
12-12-2011, 11:44 AM
Maybe the high damping factor on Pro Audio amps is based on they usually have a long run on their speaker cables. It takes a lot of wire to run from the amp racks to the Line Arrays above a stadium.

goldear
12-12-2011, 02:48 PM
Couldn't have said it any better myself :-)
(although, FWIW, the part about vacuum tube amps' sound that I really enjoy has nothing to do with LF performance...)

I agree. DF is buy no means the only difference between the sound of SS amps vs. tube amps, nor is it even the most significant difference. But it certainly does contribute to some degree.