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PMA-NC252MP power amplifier

pkane

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It is measured by a 2-channel method, both amplitude and phase error of the soundcard are compensated by comparing a measured channel with a reference channel. This is more difficult to make properly in REW, which asks for impulse response delay compensation and time shift, otherwise REW gives improper results in phase response.
Given enough motivation (and I didn't have much to do the phase curve for PA5 :) ), I'd do this with DeltaWave. You can even use your two-channel method and compute delta phase between the two channels. But even without it, DW can remove any delays between two recordings.
 

maty

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So this is what I am listening to now, the newest piece in my music collection. And yes, I like physical sound recording media.

View attachment 175746

Rattle, Berliner P - Beethoven Symphonies 1-9 (2016), Vinyl x10, Berliner Philharmoniker Recordings, Germany
Front.jpg



DR Peak RMS Duration Track
--------------------------------------------------------------------------------
DR14 -2.39 dB -21.91 dB 8:37 01-Symphony No. 1: 1. Adagio molto - Allegro con brio
DR14 -6.66 dB -25.64 dB 7:16 02-Symphony No. 1: 2. Andante cantabile con moto
DR12 -2.67 dB -20.92 dB 3:24 03-Symphony No. 1: 3. Menuetto: Allegro molto e vivace - Trio
DR14 -1.48 dB -20.97 dB 5:25 04-Symphony No. 1: 4. Finale: Adagio - Allegro molto e vivace
DR14 -1.89 dB -20.04 dB 11:33 05-Symphony No. 2: 1. Adagio - Allegro con brio
DR14 -4.00 dB -24.62 dB 9:53 06-Symphony No. 2: 2. Larghetto
DR16 -2.13 dB -22.64 dB 3:24 07-Symphony No. 2: 3. Scherzo: Allegro - Trio
DR14 -0.57 dB -20.06 dB 6:00 08-Symphony No. 2: 4. Finale: Allegro molto
DR14 -0.51 dB -19.78 dB 16:20 09-Symphony No. 3: 1. Allegro con brio
DR15 -0.51 dB -21.61 dB 15:17 10-Symphony No. 3: 2. Marcia funebre: Adagio assai
DR14 -0.51 dB -20.75 dB 5:50 11-Symphony No. 3: 3. Scherzo: Allegro vivace - Trio
DR14 -0.51 dB -19.85 dB 11:42 12-Symphony No. 3: 4. Finale: Allegro molto - Poco andante - Presto
DR14 -0.51 dB -19.78 dB 11:36 13-Symphony No. 4: 1. Adagio - Allegro vivace
DR16 -0.51 dB -22.89 dB 9:45 14-Symphony No. 4: 2. Adagio
DR13 -2.64 dB -21.64 dB 5:30 15-Symphony No. 4: 3. Allegro molto e vivace - Trio: Un poco meno allegro - Tempo I - Un poco meno allegro
DR13 -0.71 dB -19.48 dB 6:37 16-Symphony No. 4: 4. Allegro ma non troppo
DR13 -0.51 dB -18.11 dB 6:59 17-Symphony No. 5: 1. Allegro con brio
DR14 -0.51 dB -21.44 dB 9:03 18-Symphony No. 5: 2. Andante con moto
DR14 -0.59 dB -21.97 dB 4:35 19-Symphony No. 5: 3. Allegro
DR12 -0.51 dB -16.10 dB 9:55 20-Symphony No. 5: 4. Allegro - Presto
DR13 -3.61 dB -22.56 dB 12:00 21-Symphony No. 6: 1. Angenehme, heitere Empfindungen, welche bei der Ankunft auf dem Lande im Menschen erwachen: Allegro ma non troppo
DR13 -7.31 dB -25.86 dB 11:56 22-Symphony No. 6: 2. Szene am Bach: Andante molto mosso
DR12 -3.89 dB -20.76 dB 5:05 23-Symphony No. 6: 3. Lustiges Zusammensein der Landleute: Allegro
DR12 -0.51 dB -17.37 dB 3:52 24-Symphony No. 6: 4. Donner Sturm: Allegro
DR13 -2.30 dB -20.57 dB 9:42 25-Symphony No. 6: 5. Hirtengesang Wohltätige, mit Dank an die Gottheit verbundene Gefühle nach dem Sturm: Allegretto
DR14 -0.51 dB -18.45 dB 13:45 26-Symphony No. 7: 1. Poco sostenuto - Vivace
DR15 -0.51 dB -23.08 dB 8:42 27-Symphony No. 7: 2. Allegretto
DR13 -0.51 dB -19.54 dB 8:27 28-Symphony No. 7: 3. Presto - Trio I und II: Assai meno presto
DR11 -0.51 dB -15.86 dB 8:17 29-Symphony No. 7: 4. Allegro con brio
DR14 -0.51 dB -18.83 dB 9:11 30-Symphony No. 8: 1. Allegro vivace e con brio
DR14 -4.41 dB -25.67 dB 3:53 31-Symphony No. 8: 2. Allegretto scherzando
DR14 -2.97 dB -21.58 dB 4:39 32-Symphony No. 8: 3. Tempo di Menuetto - Trio
DR14 -0.51 dB -19.20 dB 7:26 33-Symphony No. 8: 4. Allegro vivace
DR13 -0.51 dB -18.28 dB 15:20 34-Symphony No. 9: 1. Allegro ma non troppo e un poco maestoso
DR15 -0.51 dB -20.40 dB 13:33 35-Symphony No. 9: 2. Molto vivace - Presto - Molto vivace - Presto
DR18 -1.75 dB -25.30 dB 15:55 36-Symphony No. 9: 3. Adagio molto e cantabile
DR14 -0.51 dB -20.25 dB 6:06 37-Symphony No. 9: 4a. Presto
DR10 -0.50 dB -15.09 dB 16:58 38-Symphony No. 9: 4b. Presto - Recitativo »O Freunde, nicht diese Töne«
--------------------------------------------------------------------------------

Number of tracks: 38
Official DR value: DR14
 
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sarumbear

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This is a photo for you ;).

View attachment 174059
According to the HYPEX datasheet the module's combined efficient at 500W is around 82%, which means the heath generated at that maximum output is less than 90W. That looks to be well within the capacity of one heatsink you use. I realise that you buy in the cases but isn't it a an overkill to have two heatsinks and leave one unused?

Also, may I ask why you have used two different gauge speaker cables and have to clamp them together, instead of using a single cable from the module to the speaker terminals?
 
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pma

pma

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According to the HYPEX datasheet the module's combined efficient at 500W is around 82%, which means the heath generated at that maximum output is less than 90W. That looks to be well within the capacity of one heatsink you use. I realise that you buy in the cases but isn't it a an overkill to have two heatsinks and leave one unused?

Also, may I ask why you have used two different gauge speaker cables and have to clamp them together, instead of using a single cable from the module to the speaker terminals?

I already have had the box here left from another amplifier project, so it was convenient for me to use it. The cable solution was just to make it quickly, as I have mentioned, this is just a functional sample. The cable with 4-pin Molex to fit into the module was a part of Hypex NCxxxMP eval board delivery (same for XLR input cables /they are perfectly shielded/ and the power cable which I have provided with second insulation. I have measured no issues. I do not think that this cable thing is important.
 

sarumbear

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I already have had the box here left from another amplifier project, so it was convenient for me to use it. The cable solution was just to make it quickly, as I have mentioned, this is just a functional sample. The cable with 4-pin Molex to fit into the module was a part of Hypex NCxxxMP eval board delivery (same for XLR input cables /they are perfectly shielded/ and the power cable which I have provided with second insulation. I have measured no issues. I do not think that this cable thing is important.
Thank you for the explanation.
 

CDMC

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This product will be a dismal failure. Have the case anodized champagne colored, put some magic wires in, a fancy faceplace, and have some steel plates added to bring it up to 75 pounds and you should be able to sell as many as you want for $6,000 a piece. I would suggest also selling a monoblock version with only one channel used in each case so the power supply isn't taxed. You could sell those for $5,000 each. ;)
 

Larry B. Larabee

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This product will be a dismal failure. Have the case anodized champagne colored, put some magic wires in, a fancy faceplace, and have some steel plates added to bring it up to 75 pounds and you should be able to sell as many as you want for $6,000 a piece. I would suggest also selling a monoblock version with only one channel used in each case so the power supply isn't taxed. You could sell those for $5,000 each. ;)
Have to agree.
If I were you I would milk this for what it's worth, one of the few sota class d amps available deserves well executed high profile marketing and a web site, a presence in the underground and saturation in the professional review pages. Then, you need a new name for the amp, a price double what you estimated (caché) and to stop assembling them on your kitchen table because, of course, demand will be through the roof. Just sell me mine for the 2k you figured for retail before you go through with this (LOL). Hell, make that an introductory offer for all ASR members while you get retooled for the onslaught.

Speaking of caché, an ASR 'name the amp' contest gets one for free (the winner pays shipping).

Opportunity is knocking.
 

Matias

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Can you test multitone in 4 ohms, multiple power levels? I am curious. Thanks in advance.
 
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pma

pma

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Better idea with 4 Ohms
Post #1 of this thread :). It was the 8 ohm measurement that was missing and has been done today (I had to re-configure the load resistors).

BTW, to summarize:
2 x 250W/4ohm at 1% THD
2 x 150W/8ohm at 1% THD
SINAD 98.15dB/5W/4ohm/1kHz
This just confirms Hypex datasheet parameters.

2x200W/4ohm and 2x100W/8ohm below the "knee" of THD plot that indicates to start of clipping.
 
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pma

pma

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Can you test multitone in 4 ohms, multiple power levels? I am curious. Thanks in advance.

Hello Matias, regarding your request, I have some troubles when measuring the multitone and HF distortion - my "main" soundcard has too high HF distortion and I must use another one, which is not supported by ASIO so I cannot use REW, as it runs only in 16-bit resolution in JAVA mode.

Anyway, below is a multitone measurement in ARTA, at 5.9W/4ohm and 48kHz BW. No input LC filter used. The LF rise of noise floor is a problem of the soundcard used as well as the 250Hz spurious line. Anyway we can see that the amp does not HF linearity issues and other than mains related lines are between -110 to -120 dBr. Peak to peak amplitude of this multitone test was >41Vpp at the amplifier output.

PMA-NC252MP_4R_multitone_6W.png


PMA-NC252MP_4R_multitone_6W_wide.png


The bottom graph shows enhanced frequency range up to 45kHz. We can clearly see "noise shaping" or rather increasing ultrasound noise of the class D amplifier.
 

Matias

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Still very nice thanks!
 
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DSJR

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Better idea with 4 Ohms
I'm old fashioned - 8 ohm first as per traditional convention and then the potential increase available at 4 and maybe 2 ohms after...
 
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pma

pma

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Anyway we can see that the amp does not HF linearity issues

However, as I used to be repeating, the multitone test is not much demanding regarding amplifier HF linearity, because the individual spectral components have low amplitude. THD vs. frequency tells more and at 65W/4ohm the amp's HF linearity is not that stellar.

PMA-NC252MP_thdfreq_65W_@48kHz.png
 
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pma

pma

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I'm old fashioned - 8 ohm first as per traditional convention and then the potential increase available at 4 and maybe 2 ohms after...

I do not like the 8ohm resistive test at all because no real speaker makes such light load, because of its complex impedance. And if we go to EPDR, equivalent peak dissipation resistance, then even the speakers that seem to have reasonable magnitude curve fall below 3 ohm. The 8 ohm resistor test is IMO good only to make nice plots, and this is really not my intention. The DUT has to be pushed to the limits.
 

KSTR

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The DUT has to be pushed to the limits
Yes, 8 ohm resistive load is useless as a pushing load, and even 4 ohm isn't really that hard.

The rule of thumb (as established eg by Bob Cordell) for worst-case is that an amp should be capable of driving a current equivalent to full output voltage into 1/3rd of the rated impedance of a speaker, for transients (as that current peak can only appear for a short time). Which means a 1.3 ohm test load for 4 ohm speaker!
For class-D amps this equivalent load can be used as is (as phase angle doesn't matter for class-D) but for linear amps this ohmic load may not be enough for proper testing as any SOA protection which factors in voltage and current might actually trigger with reactive load while it doesn't with ohmic loads.

I'm aware that you know this, Pavel, this is meant as info for other members.
 

peng

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I do not like the 8ohm resistive test at all because no real speaker makes such light load, because of its complex impedance. And if we go to EPDR, equivalent peak dissipation resistance, then even the speakers that seem to have reasonable magnitude curve fall below 3 ohm. The 8 ohm resistor test is IMO good only to make nice plots, and this is really not my intention. The DUT has to be pushed to the limits.

I agree with you completely, except just want to note that the dissipation equivalency is just for heat dissipation equivalence (and I know you know that obviously:)), while useful for sure, but I think the way it had been portraited by users such as JA (Stereophile), and probably JC (re: the Benchmark article) could potentially mislead people that an amp may not be adequate to push current during the low impedance dips (example: below 4 ohms) of a loudspeaker based on the test results using such method, when in fact current may not always be the problem for the said amp (because current still = V/|Z|, |Z| is the absolute value of the complex impedance, so 4 ohms is still 4 ohms complex or not), but heat is.
 

Savi

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Hi. I am planning on building a 6 Ch AMP (I already have 3 module nc252mp but I will probably only use 2 + something else because the nc252mp is overkill for tweeters ;)). Regarding thermal dissipation do you think this kind of copper plate (for GPU) could be useful or its a waste of money (30 euros each with 5mm thickness) ?
 

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