Damping Factor

[YiannisK]

Hi James and many thanks for the kind words

My experience matches what you wrote. More specifically, the B&Ws sounded a lot better when driven by the Rega Elicit as compared to the Naim 5si and NaimV1+Nap 250DR. The Arcam A29 also kind of struggles with the B&Ws. This 'struggle' is expressed as bass boom and bass overhang. I observed this both in my own living room (more pronounced) but also during the audition (much larger room with acoustic damping all around). The acoustic damping in the audition room helped contain the bass boom but my own living room does not benefit from any such treatment. I did some furtner research and it does appear that the B&W CM1 S2 has impedance lows that reach below 4ohms. Even more interesting that these impedance lows are around the 50 - 150 Hz area of the frequency spectrum. Maybe this all explains a bit why Arcam and Naim are described as not a good match with B&W speakers. It also might explain what some people describe as a full, soft characted from Arcam Amps. A bit curious though how a low DF translates as a (widely reported) superior PRAT by Naim amps. Maybe there is something else that is not measured (yet) and which influences the perception of the Naim sound.

I hope all the above does not come across as a criticism of any amp... I am merely curious after finding it difficult to match amps and speakers.

Cheers

Interesting post Yiannis, and nothing wrong I think with resurrecting a thread like this that deals with a specific, important element of music-making that is rarely discussed. I have come to think that damping factor is a really important element in amp-speaker synergy - there is no right answer here to what the damping factor should be (contrary to some suggestions that the higher the damping factor the better); rather it is a matter of system matching and some speakers, many modern speakers in fact, including the B + W you were listening to, seem to respond best to amps with a higher DF, while others (Triangle, Magnepan) seem to be better suited to amps with a lower DF. Spec sheets can help point in the right direction in terms of putting together an auditioning short-list, but as always listening is the key, and this is where your own findings are interesting.

 

[Ashley James]

You can hear the effect of the Amp's output impedance on active speakers, but Martin got hold of a sixties Heathkit valve amp, went right through it and optimised it for the lowest possible distortion etc so that we could compare it with modern soldid state on good passives The result was that we struggled to hear any difference.

What we did find was that if the amp had a high output value impedance, it affects the crossover. It raises the bass crossover point and lowers the tweeter one, so you get more overlap and in theory the speakers should have sounded harsher. Passives sound harsher than actives and we could say it was audible.

 

[YiannisK]

Interesting!

Lack of bass control was indeed what I heared when I auditioned the Naim 5si paired with B&W but also when I tried the Kef R100s. Bass overhang and boom.

Maybe this low DF will be an asset if the Naim is paired with PMC? I remember trying them with Rega amps and the bass sounded so tight that it was missing fullness. Could be that the famed NAIM + PMC synergy is partly explained by this?

I once tried the following system at home: Naim Dac V1 + Naim Nap 200 (non DR version) driving a pair of Monitor Audio RX1 speakers. Really bad sound. Super dry, chopped vocals, start-stop sound, harsh highs (really uncomfortable), non existant bass. I would have expected the low DF in that system to result into a fullsome bass but that was not the case. The Arcam A19 on the other hand was a good match with these speakers.

Too many questions I 'm afraid and sorry for the lengthy brainstorm.

Best

Yiannis

Back in the day, I am thinking 'olive' series Naim here, their damping factor was so low and their control at low frequencies so poor that they sounded slow and 'ploddy' with virtually any speakers with an extended bass response.

Naturally Naim blamed this on the speakers, accusing them of being 'out of tune' or lacking 'prat', thus consigning a whole generation of perfectly decent speakers to oblivion, as of course, it was the lack of control from their amplifier that was the real issue.

 

[YiannisK]

Many thanks for sharing this Ashley. So it does seem more is at play when it comes to the DF effect on speaker behaviour. I had a suspicion this was more complex .

Overall and assuming other THD and S/N figures are good, would you suggest that a higher DF is better than a low DF? If an amp manages a really really high DF, would that be a bad thing if matched with some speakers?

Best

Yiannis

You can hear the effect of the Amp's output impedance on active speakers, but Martin got hold of a sixties Heathkit valve amp, went right through it and optimised it for the lowest possible distortion etc so that we could compare it with modern soldid state on good passives The result was that we struggled to hear any difference.

What we did find was that if the amp had a high output value impedance, it affects the crossover. It raises the bass crossover point and lowers the tweeter one, so you get more overlap and in theory the speakers should have sounded harsher. Passives sound harsher than actives and we could say it was audible.