Monitor Audio PL100-3G 'nominal impedance' vs 'minimum impedance'

[epping4est]

I agree, "It does not work that way.", but I'm confident that the M23 can deal with the PL100-3G's 4-ohm dips. There's a lot of music within those 4-ohm dips, but also a lot of music outside those dips. [My original concern was that the PL100-3G's 'nominal' impedance could fall below 4 ohms.]

An alternative to bridging the M23 is to bi-amp the M23 -- e.g. Plan-B. The PL100-3G's crossover point is 2850Hz -- i.e. not identical to the 1G's. The impedance curve above 2850Hz will be pretty much 10 ohms or more. So if horizontal bi-amping, then the HF M23 would see mostly 10 ohms while the LF M23 would see mostly 4 ohms -- 175W at the HF and 400W at the LF. Might sound fine, but might not. I intend to try all options.

 

[Vladimir Filevski]

So if horizontal bi-amping, then the HF M23 would see mostly 10 ohms ... -- 175W at the HF

Edit:
Addendum
Average, nominal and minimum loudspeaker impedance may confuse some audiophiles. So let calculate with the respect to the voltage only:
PL100 has 85dB/2.83V/1m sensitivity.
M23 has maximum 400 W output at 4 ohm load. That is at least 40 V clean output voltage irrespective of the load value - equal or higher than 4 ohms. (including 10 ohms)
PL100 with 40 V clean input (should) have 106.5 dB/1m output. But, PL100 will distort heavily at that level.

 

[epping4est]

I agree that "It does not work that way." i.e. The PL100-3G's 'nominal impedance' is indeed 4 ohms, but never less than 4 ohms -- which was my original concern. In fact, the vast majority of the curve lies above 8 ohms. Both the bridged M23 and its connected PL100-3G will be fine.

I think I disagree with the 'Addendum' ...

Monitor Audio employs a crossover at 2850Hz on the PL100-3G. If I bi-amp a PL100-3G, then the LF impedance will (often) be 4 ohms, while the HF impedance will (mostly) be 10 ohms. It seems unlikely that both the LF M23 and the HF M23 would deliver the same power.

 

[DonH56]

Musical recording with 20 dB peaks over average are few and far between. Very good (excellent!) classical music recordingс have 15 dB peaks, pop and rock usually less.

I checked but no longer have the data I took from long ago. I have a few orchestra pieces that hit the 20 dB range, though 15~17 dB is more like it, but interestingly the most dynamic are a number of small-group recordings that have very high peaks due mainly to the drums coming on top of the other instruments (acoustic bass, guitar, piano IIRC for one old RTF or Chick Corea piece).

Agree with your post.

 

[epping4est]

Try 'Penguins' from Lyle Lovett's 'I Love Everybody' album; fabulous dynamics on the snare [trap?] drum. Ditto on 'Ghetto of My Mind' from Rickie Lee Jones' 'Flying Cowboys' album. I don't have the 'dB' numbers handy, but I've read that they're quite high.

Edit:
According to the Dynamic Range DB (DB = database; not dB )

1. Rickie Lee Jones' Flying Cowboys album, Ghetto of My Mind has a dynamic range of 24dB
2. Lyle Lovett's I Love Everybody album, Penguins has a dynamic range of 16dB

The same website allows the album list to be sorted by maximum DR, which indicates that some CDs have DRs up to 34dB. e.g. On YT is this (4-hands/2-piano) piano piece, Abenlied by Schumann, as performed by Katia & Marielle Labèque. The Dynamic Range DB says that the piece (from the duo's Encore! album) has a DR of 32dB.

 

[Vladimir Filevski]

the LF impedance will (often) be 4 ohms, while the HF impedance will (mostly) be 10 ohms. It seems unlikely that both the LF M23 and the HF M23 would deliver the same power.

... but delivered maximum voltage will be at least 40 V, both for LF and MF, asking from PL100 output of SPL=106.5 dB/1m, both at LF and HF. At such high output PL100 will distort. Whether it will survive, is a different question. However, civilized use (not at the maximum!) will be OK.

I think I disagree with the 'Addendum' ...

I give up, again...

 

[epping4est]

I give up, again...

Don't do that!

Let's get back to known facts rather than theoretics ... Even as I type this reply I'm listening to my PL100-3Gs being driven by a Moon W5 rated at 380W into 4 ohms. The unqualified prediction [e.g. amp input sensitivity] was that the speakers would destruct at 300W let alone at 380W of power. Of course, both are fine.

Of course, I do not listen at the Moon W5's full rated output power. The amp doesn't have 'View' meters, but I suspect that the W5 is not working hard at all -- likely much less than 1W of output power. Likewise, I do not intend to listen to the NAD M23s at their full rated output power -- regardless of the amp and loudspeaker configurations. I anticipate better-than-satisfactory sound with bridged M23s and I anticipate that neither the bridged amp nor the loudspeaker will be troubled by the configuration.

If I find that horizontal [vertical] bi-amping sounds just as good, then I'll bi-amp; there would be no audible benefit to bridged amplification.

 

[Vladimir Filevski]

Of course, I do not listen at the Moon W5's full rated output power...
Likewise, I do not intend to listen to the NAD M23s at their full rated output power

answer before you asked:

civilized use (not at the maximum!) will be OK.

Let's get back to known facts rather than theoretics

My friend have service business for more than 30 years. Shelves in his workshop are full of broken amplifiers and loudspeakers - painful consequence of clashing "theoretics" with known facts.

W5 is not working hard at all -- likely much less than 1W of output power.

Which raises important question - why on earth you need 400W amplifier? Or 700 W biamping?

 

[epping4est]

Ah, so we were in violent agreement all along.

 

[Vladimir Filevski]

I don't understand your point. But I am aware my English is not good enough, so...
Enough of this, I am out.

 

[epping4est]

@Vladimir Filevski - Check out 'violent agreement'.

I also noticed that you altered [added to] your post after I made my reply. There's an annoying delay between the time you post [or edit your post] and the time your post reaches this forum's web page.

Summary: I accept your viewpoint.

 

[epping4est]

Subjective listening ...
I have since listened for several hours to all three of the above configurations and bridged sounds best. I was mistaken to have even considered horizontal bi-amping as an option because the L/R channels of an M23 share a single power supply. Vertical bi-amping predictably proved to have better sound, with deeper bass and superior channel separation. The two M23s operating in bridged mode proved even better than the same two vertically bi-amped M23s. In bridged mode, the M23s expanded the soundstage while delivering even more textured bass and exceptional imaging. I was particularly impressed by the depth of the bass on London Grammar's Hey Now and by its improved texture on Crash Test Dummies' Keep a Lid on Things. The imaging on Eric Clapton's Malted Milk [live; 'Unplugged'] is noteworthy. My listening room is rather small -- maybe 3m x 4m -- so the bridged M23s are not at all stressed to drive my PL100s to [even uncomfortably] loud SPLs.

See also: NAD M23 Amplifier Review by Audioholics

 

[Beave]

Next, set up a way to try those various configurations without knowing which you're listening to, and watch as all those subjective impressions (like widened soundstage) become unreproducible.

 

[epping4est]

The two salient configurations are 1) Vertical Bi-Amp; and 2) Dual-Mono Amp:

Bi-wiring a bridged M23 requires that the amp-ends of the speaker cables are able to span the 20cm distance between the M23's right-negative and left-positive terminals. My cables cannot span that distance, so I employed a very short pair of female-to-male banana cables [not shown]. I will eventually move the M23s to the floor beside the speakers and replace the current 10-foot speaker cables with much shorter cables.

Addendum:
I should mention that I also have a pair of subwoofers requiring a full-range signal from the pre-amp [to which the subs apply a low-pass filter]. Initially I split an XLR feed from each of the pre-amp's XLR outputs, but that strategy resulted in poor sound -- perhaps because I introduced too many splits -- e.g. one at the pre-amp's left (right) XLR output and another at the sub's left and right XLR inputs, plus the already employed split at the vertically bi-amped M23. Instead, I used the pre-amp's left (right) RCA output into an RCA-to-XLR buffer [Aphex 124A level matcher], and then XLR to a splitter at the sub.

 

[pogo]

I have since listened for several hours to all three of the above configurations and bridged sounds best.

The Dali Kore have an impedance minimum of 3.3Ohms at 65Hz. Considering that these are usually driven with four bridged NAD M23, that's quite a feat for any Purifi module. In bridge mode this impedance is halved for the Purifis, i.e. 1.65ohm and seems to work well in real life.

Here are my listening impressions of the Epikore 11 with bridged Purifis: Link

Btw, the M33 V2 and M23 V2 have been announced for August and may be able to achieve even better sound quality with the 2nd gen Purifis in bridge-mode.

 

[MatrixS2000]

There are no musical recordings with 30 dB musical peaks!

 

[Vladimir Filevski]

@MatrixS2000

Actually, there are only 2 known musical recordings in the existence with over 26 dB peaks.

Congratulations, you found the third one!
Or maybe it is one of those two I mentioned?
Wait a minute... what am I seeing? What is the average level of your recording? Is average level above 12 dB? With those absolute level 30 dB peaks, then it is 30 - 12 = 18 dB peak over average level. Only 18 dB above average level? Am I reading wrong your measurements?

 

[epping4est]

The Dynamic Range DB represents a very small fraction of all recordings, but anyway lists quite a few recordings having a DR of more than 26 dB -- including many having a DR of 30 dB or more.

 

[MatrixS2000]

Am I reading wrong your measurements?

Yes.

 

[Vladimir Filevski]

The Dynamic Range DB represents a very small fraction of all recordings, but anyway lists quite a few recordings having a DR of more than 26 dB -- including many having a DR of 30 dB or more.

Dynamic Range DB strongly disagrees with you:

As far as I can see, in this database there are only 2 albums with DR higher than 26 dB. Two (2) is not "quite a few" nor "many".
Of course Dynamic Range DB do not contain all recordings in the existence, but they analyzed 185162 albums (!), so if only 2 albums out of 185,162 have DR over 26 dB, then we can safely conclude: albums with DR range higher than 26 dB are very, very rare.
Or maybe your record collection consist of albums with DR>26dB exclusively? Indeed, how many albums do you have in your collection with DR>26 (30) dB?