An amplifier can have a high damping factor but length of cable run and wire gauge can easily knock it down which lessens the amount of control the amp has overs the drivers, mainly the woofers. Crown Audio used to include a chart in its owner manuals for determining what gauge wire needed to be used for a given run length to maintain the damping factor of its amps. Here is a good explanation of damping factor and how it influences speaker performance: http://www.crownaudio.com/media/pdf/amps/damping_factor.pdf A factor of 640 is good, but even less expensive pro and consumer amps can have a higher measured damping factor. An interesting topic would be how exotic speaker cable construction influences damping factor and subsequent driver control.
The link doesn’t seem to work, so you can google “understanding damping factor” and the top link will be to the pdf.
Alekz said
Does that mean that the damping factor does not matter for speakers with active subwoofers, like Martin Logan Summit?
BHK here: Sure it does! Damping factor is a measure of output impedance of an amplifier and is usually expressed as Zo = 8/DF the number 8 being an assumed 8 Ohm typical speaker impedance and a long time standard for the DF calculation, it itself being DF = 8/Zo. Now, speakers with an active woofer usually have a high pass crossover filter that cuts out the low frequencies from the rest of the speakers drivers and start to act somewhere around 50-150 Hz. My Genesis Advanced Technologies 6/1 speakers are like this. The consequence of this is that the input impedance to the speaker starts to rise as frequency lowers in this frequency range. Now with an amplifier that has a high damping factor, the output of the amplifier won't change as the speaker's input impedance rises as frequency goes lower with the result that the overall tonal balance of the speaker will be as intended. BUT with an amplifier with a low damping factor, say 8 of a typical tube amp, the output voltage will rise in the bass range because as the impedance of the speaker rises, so will it's output voltage and resultant acoustic output. Bottom line, there will be some tonality imbalance that mostly can be fixed by the bass level control on the speaker's bass section.
Interesting, beyond the result itself, once confirmed, as it may play into the Parallel amplification line of inquiry that seems to be Paul’s hunch on why the Mono amaze him.
@BHK: I'm dying to know if you confirmed that damping factor measurement on retest. 640 would be off the charts...
BHK Here: On that damping factor comment that I posted earlier on the Sig 300, it was a measurement error and the value is just about twice that of the Sig 250 as one would expect. the Sig 250 is about 140 and the Sig 300 is about 280.
The last I heard was that we are waiting on BHK to finish testing the one Mono amp he was given. Once that is done, then they can be built and shipped out. Earlier this week we were told hopefully by the end of this week. Now I am not so sure.
I other day I got an email from Fedex with a shipment from PS Audio. Unfortunately it was only a envelope. It must be the demo disk coming today. At least we are getting closer.
Alan W said
The last I heard was that we are waiting on BHK to finish testing the one Mono amp he was given. Once that is done, then they can be built and shipped out. Earlier this week we were told hopefully by the end of this week. Now I am not so sure.
I other day I got an email from Fedex with a shipment from PS Audio. Unfortunately it was only a envelope. It must be the demo disk coming today. At least we are getting closer.
it is a demo disk, manual, and some instructions Alan. I got mine yesterday. Some really good tracks, some i was familiar with and others never had heard. I listened through them on my current system last night but plan on trying to do a little bit more critical listening today in advance of the mono’s arrival to familiarize myself with them better.
incidentally scott mentioned to me that BHK had given the ok for production, but that since it’s getting squeezed into the schedule with personnel assembling P10’s etc., that it may be pushed until the first of next week before we see shipping notices…perhaps scott can update us again here at some point.
Just got my envelope today in the mail. I will listen over the weekend. I’ll be busy watching the Cavs playoff basketball game tonight and heading to the home game Sunday night in Cleveland.
Guys - Paul attempted to use Class D designs including the NCores, but they failed to meet his lofty goals to achieve the highest level of sonic performance which the BHK apparently does. Credit should be given to Paul for not settling for anything less, and then going out to hire one of the most experienced and well thought of amplifier designers around to create the true amplifier of his dreams. It sounds like we are all be the beneficiaries of his plan’s execution.
I never meant to imply the 400 or even the 1200 was as good as the BHK, I haven’t heard either of these, was only adding to mark-d’s comment that the NCore D’s are exceptional.
I’m curious if any of the usual reviewer suspects (TAS, Stereophile, etc) have picked up an amplifier yet, Stereo or Monos, for review? Are you allowed to say or/and if so, any idea when these review(s) will be published?
(Edit): It looks like JVS has posted some very positive initial feedback from Munich notwithstanding the room’s acoustical challenges. Makes me all the more excited for the monos to arrive…
audio.bill said
Credit should be given to Paul for not settling for anything less
Yes, as a newcomer to PS Audio, I was very, very impressed to learn that Paul had engaged in such a public process, then canned it - publicly, acknowledging that he had found a better way forward.
No doubt a little frustrating for the delay, but really, who wouldn’t be grateful that the amp they get to buy (if they were buying) is considered by all involved to be so much better.
As I understand BHK, it is a no-compromises design that comes in with a market leading price, for the performance level. Paul’s currently detailing the benefits of “parallel processing”, “analog style” - none of which is going to come with a power-efficient, fast switching, class d amplifier design.
If you want Class D amps, maybe try the baby Kharma monoblocks, great footprint, nice sound (with Kharma speakers) & reasonable cost. No doubt very low power. Given the sound quality I heard, no doubt based on good class-d amps. Or the myriad of others that must soon be on the market using these standardised, non-differentiated building blocks. Hope they get cheap enough to power multi-room solutions, that would be cool.
But, not BHK cool, going by Alekz’s latest beta report, which is not even the parallel Mono’s Paul loves even more than BHK’s stereo.
In reply to Streets Still Works (But even Hypex admits the NCore 400’s aren’t as good as the 1200’s and amps using the latter cost more than the BHK . . . .) You are partially right They are more expensive than the Stereo version of the BHK’s but are cheaper than the mono version. Case in point The Merrill Audio Veritas monos cost $12000/ pair and the BHK monos cost $15000/ pair.
I thought there was going to be a comparison done soon on the BHK’s and other either newer like the Merrills or against the other amp mentioned in the video? Is this ever going to happen? I believe that the BHK’s are VERY good amp or amps but I have nothing to compare them to.
As these amps find their way into people’s home plenty of comparisons will be posted. So far, the stereo has already beaten a few much pricier incumbents. I personally will put a pair of monos up against the highly acclaimed Spectral 360 MKII monos, and report my findings.
