[planet10]

in the real world 8000 is no different than 100.

R_out = 0.001Ω (damp = 8000)
R_out = 0.08Ω (damp = 100)

Add 0.02Ω of speaker wire and it becomes 0.021, vrs 0.1. both still way less than 0. And there is a very good chance the damping factor comes from the marketing department than the engineering department.

It is unlikely, very unlikely, that the damping is actually doing what is being expressed.

dave

[RDavidson]

Agree. Damping factor is only one parameter of an amplifier's performance, but clearly not the only one. The train of thought that damping factor is a primary contributor to audible performance is drawing a conclusion based on incomplete information. While I'm sure that Devialet amps (and other well engineered class D amps) sound great and exhibit excellent bass tone and control, I think this is perhaps more of a product of their design and THD+N moreso than their damping factor alone. Really, the same can be said of any well designed and engineered amplifier irrespective of type or class.

[NoahH]

Purifi Class D monoblocks with huge LPS (1500VA, 134,000uF for each monoblock)

Um - come again? Is this a custom job? Are there photos? I am intrigued. How exactly did those compare to the XA60.8s? I have heavily wondered what something like that would sound like.

[Jaytor]

Um - come again? Is this a custom job? Are there photos? I am intrigued. How exactly did those compare to the XA60.8s? I have heavily wondered what something like that would sound like.

Yes, they are DIY. Check out this post https://www.audiocircle.com/index.php?topic=171798.msg1844352#msg1844352.  These photos show the build (for one channel) with the Neurochrome input buffers. I currently have the VTV tube input buffers (shown later in the thread) installed.

Initially, I wasn't that happy with the VTV buffers, but I recently tried these amps again after I changed the room acoustics and installed ATS Acoustics QRD diffusers. These amps are a much better match to the livelier sound of the room now.

I haven't compared them head-to-head with the Pass amps in quite a while, and not since I added the diffusers, so I hesitate to make direct comparisons. When I got the Pass amps, I had been using the Purifi amps with the VTV buffers, and I thought the Pass amps were an improvement - more richness to the sound, particularly male vocals, and longer decay of notes.

The Pass amps have been boxed up for a while and are big and heavy so not easy to move in and out of my system. I haven't decided whether I am going to keep them since I am enjoying my 300B amps. I pulled out REW and my measurement mic yesterday and fine-tuned the subwoofers. I also hooked up the amps without a high-pass series capacitor, and the sound of my system with the 300Bs is now really sounding great. I think the series cap adds too much phase shift to the lower few octaves. Removing the cap and doing a better job blending the subs has really improved weightiness of the upper bass.

[mkrawcz]

Jaytor, are you going to be getting around to building your Folsom amp soon? I am curious to hear your input on how they compare to your pass amps.

[NoahH]

Jaytor - you are a man after my own heart. That is a serious supply.

I saw all the notes in there about the regulated supplies to the inputs and such, but for clarity, is the ultimate output stage of the Purifis regulated or unregulated?

[Jaytor]

Jaytor, are you going to be getting around to building your Folsom amp soon? I am curious to hear your input on how they compare to your pass amps.

I think I have most of the parts (other than power supply and chassis), but I've got a couple of other projects in mind that I will likely do first.

Jaytor - you are a man after my own heart. That is a serious supply.

I saw all the notes in there about the regulated supplies to the inputs and such, but for clarity, is the ultimate output stage of the Purifis regulated or unregulated?

The +/- 65v supply is just heavily filtered (CRC). The low voltage supplies are all regulated.

[Freo-1]

Agree. Damping factor is only one parameter of an amplifier's performance, but clearly not the only one. The train of thought that damping factor is a primary contributor to audible performance is drawing a conclusion based on incomplete information. While I'm sure that Devialet amps (and other well engineered class D amps) sound great and exhibit excellent bass tone and control, I think this is perhaps more of a product of their design and THD+N moreso than their damping factor alone. Really, the same can be said of any well designed and engineered amplifier irrespective of type or class.

Agreed. Damping factor seems to primarily impact the bass region.   When I had ESL speakers,  damping wasn't much of a concern.  Didn't pay much attention to damping until obtaining a Devialet with SAM configured for a pair of Dynaudio Focus 360 speakers.  The difference with the bass region was quite significant.  This was coming from McIntosh and Pass Labs amps. 

[opnly bafld]

Agreed. Damping factor seems to primarily impact the bass region.   When I had ESL speakers,  damping wasn't much of a concern.  Didn't pay much attention to damping until obtaining a Devialet with SAM configured for a pair of Dynaudio Focus 360 speakers.  The difference with the bass region was quite significant.  This was coming from McIntosh and Pass Labs amps.

DSP, not DF?

Obviously McIntosh and Pass Labs are not very good amp designers or else they would have a much higher DF.

[I.Greyhound Fan]

DSP, not DF?

Obviously McIntosh and Pass Labs are not very good amp designers or else they would have a much higher DF.

It is a matter of taste.  I have read quite a few posts of people who felt that the bass on some Pass gear is too slow.  I personally like a little slower bass.  I find it more pleasing, musical and natural but others certainly do not feel the same as tastes are different.  When I go to concerts, I find that bass is not usually very fast and tight.

[Freo-1]

DSP, not DF?

Obviously McIntosh and Pass Labs are not very good amp designers or else they would have a much higher DF.

You obviously didn't read the earlier post regarding Pass Labs. 

[opnly bafld]

You obviously didn't read the earlier post regarding Pass Labs.

Maybe I just didn't agree with it.

[Tyson]

Problem with highly damped amps is they often sound constipated in the midrange.  For me, I'd rather have slightly less tight bass for a much better sounding midrange.

And this is the catch-22 of our hobby.  Those amps that sound best in the bass, are almost never the amps that sound best in the mids/highs.  So you have to compromise something.  Some people choose tighter, punchier bass, other people choose a better midrange. 

This is why I tend to buy speakers that have self-powered bass sections.  That way a highly damped SS amp can drive the bass like a fiend, and I can use a more beautiful sounding amp on the mids/highs. 

If you have a fully passive full range speaker, it is VERY difficult to find a single amp to drive it that has brute force grunt down low and any kind of finesse higher up.  It's possible but my experience has been that those amps are both very rare and very expensive. 

[planet10]

Damping factor seems to primarily impact the bass region.

That is what we talk about, but it, or rather the R_out, can affect how things work out if the loudspeaker has an “ugly” impedance.

If you have a SET that big whoop a the XO point (a generic broadly true, but with many exceptions) will be heard. Whether to the good or the bad depends on the combination.

dave

[Freo-1]

Problem with highly damped amps is they often sound constipated in the midrange.  For me, I'd rather have slightly less tight bass for a much better sounding midrange.

And this is the catch-22 of our hobby.  Those amps that sound best in the bass, are almost never the amps that sound best in the mids/highs.  So you have to compromise something.  Some people choose tighter, punchier bass, other people choose a better midrange. 

This is why I tend to buy speakers that have self-powered bass sections.  That way a highly damped SS amp can drive the bass like a fiend, and I can use a more beautiful sounding amp on the mids/highs. 

If you have a fully passive full range speaker, it is VERY difficult to find a single amp to drive it that has brute force grunt down low and any kind of finesse higher up.  It's possible but my experience has been that those amps are both very rare and very expensive.

Funny you mention this.  For example, I have found that McIntosh amps, which tend to have low to moderate damping,  sound as if the midrange has been attenuated to some degree.  Granted,  they sound very clear,  but still not quite right.  Guess it's the old "Horses For Courses " argument. 


Interesting approach regarding speakers.  A good friend of mine has a pair of full range speakers, where the bass is powered via an internal amp, while the mids are powered via a restored Fisher KX-200.   Sounds very good!


FWIW, the Devialet Expert Pro 250 fits the description you described.

[dnhs-trey74]

Problem with highly damped amps is they often sound constipated in the midrange.  For me, I'd rather have slightly less tight bass for a much better sounding midrange.

Old Crown Macro Tech amps has extrordinarily high damping factors and just sounded broken.

Tubes or Class A for this bloke!