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NAD PP 2 Review (Analog Phono Preamplifier)

Langston Holland

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Introduction
This is actually a review of a old phono preamp that I bought off eBay for about $40 and put into use after replacing the electrolytics. The problem with this review is that it includes a short story (that you can skip!).

Short Story
I confess that I'm human. I know, I know - I need to join one of those groups where you sit in a big circle and confess it to everyone else, but I'm just not ready for that kind of commitment. Anyway, due to my problem I gave into the vinyl thing a few years ago. Briefly. For about a week. I'm so embarrassed.

What genuinely amazed me was how good a record player could sound with a good recording after only 2 months of study, spending about a grand, and a couple of dozen measurements to make it work as well as possible. The stuff: Denon DP-300F, Ortofon 2M Blue cartridge, NAD PP 2 phono preamp, and a few dozen supporting actors that don't scroll in the credits.

This included
1. Adjust Stylus headshell overhang and alignment
2. VTF Vertical Tracking Force (gauge is best)
3. VTA Vertical Tracking Angle (flat tonearm when in groove)
4. Azimuth (headshell twist results in L/R bias)
5. Anti Skate (set to same quantity as VTF)
6. Level and vibration free surface for turntable

Using
1. VTF gauge
2. Turntable protractor
3. Bubble level
4. Test records
5. Disc cleaning tools
6. Oh yeah, I do have (1) record with music instead of test signals on it

All with the glorious promise of continual maintenance, cleaning, adjusting, and replacing expensive stuff that wears quickly. I certainly understand the attraction this playback format has engendered recently. : )

Review
NAD still offers a PP 2"e" phono preamp that appears to be the same thing as the discontinued PP 2 shown in these measurements. Amir's PP 4 review demonstrated that the company can update the design in the same form factor, at a higher price and increased feature set, while significantly degrading its performance. Shame on them. Assuming the currently available PP 2e is the same design as the original PP 2, I highly recommend it at its approx. $170 street price. It beats the pants off the $2,500 item that Amir measured a few days ago. Caveat emptor.

A ground wire was attached between the PP 2 and Analyzer for all measurements. It reduced the power supply noise slightly.

Internal OEM
NAD PP-2 OEM 5.JPG


Internal Recapped
NAD PP-2 MOD 1.JPG


Moving Magnet Dashboard (5.0mV Generator Voltage)
MM Dashboard 5.0mV.PNG


Moving Coil Dashboard (0.5mV Generator Voltage)
MC Dashboard 0.5mV.PNG


PP 2 RIAA Corrected THD+N and THD vs. Generator Level at 1kHz
NAD THD+N THD 1kHz.png


PP 2 RIAA Corrected Max Output vs. THD
NAD PP2 Max Level vs THD.png


PP 2 RIAA Corrected Gain vs. Phase
NAD PP2 Gain vs Phase.png


God bless you and your precious family - Langston
 
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Phorize

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Nice, pretty solid performance.
 

JeffS7444

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Do typical record pops and tics come anywhere near to overloading the preamp?
 

USER

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Thanks for this. It brings back some good memories. This model was my first phono stage that I bought to put together my first real system. (Along with the exceptionally good and ASR reviewed NAD C320 BEE.)

Soon thereafter I got very much into the nonsense of audiophilia and replaced it with a Conrad Johnson Motif preamp that was touted as having the "greatest phono stage imaginable" or whatever. It was an early solid state model that emulated the CJ tube sound people thought was the bee's knees back then. (I also got a gigantic Forte/Threshold 50W amp). I know now that in both counts I fucked it up and switched to a worse system. Live and learn.

Again, thanks. This made my morning.
 

Rottmannash

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I wonder if this is the same circuit as in my old NAD 3140.
 
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Langston Holland

Langston Holland

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Do typical record pops and tics come anywhere near to overloading the preamp?

Someone like Amir would have to answer that - I'm a committed vinyl newbie.

BUT. I have some thoughts..

1. I'm convinced you're right to connect pops and clicks annoyance to phono preamp headroom. When clipping occurs in the analog domain (digital is worse and another topic), we perceive it as louder. Heavily clipped material can sound about 10dB louder in my experience. Generally, 9dB is considered twice as loud.

2. Nothing is free in audio. Current technology's circuit designs at a given price point afford a given signal to noise (S/N) ratio. If the phono preamp is designed to accept higher voltage levels before clipping, its noise floor will likewise increase due to the immutable no-free-lunch law. The vinyl record format has a high intrinsic noise level to begin with, so competent phono preamp designers do have a good amount of room to work with if mgt. cares about the product.

3a. Now the designer has to figure out approx. how much voltage his phono preamp will see from a "typical" MM or MC cartridge, both the average (RMS) and peak levels (momentary). The difference between these two levels is called the crest factor. I do not know the typical RMS output of a MC cartridge, but 5mV is considered typical for the MM type. You'll notice that several of Amir's measurements use a 5mV RMS generator voltage for that reason.

3b. With the PP 2, the MM max input voltage before clipping is 89.7mV. That gives the PP 2 25dB (20log(89.7/5)) of headroom, which is huge and should be more than satisfactory. The MC section clips at one-tenth that level, which is 20dB lower. Interestingly, the PP 2's gain for the MC section is 20dB higher. This tells me that the typical RMS output of a MC cartridge was expected by the designer to be 0.5mV*, and if he was right, the MC section also has 25dB of headroom.

So I'd expect the answer to your question to be "no"; pops and clicks will be reproduced cleanly.

What a crazy thing to have to design for. : )

God bless you and your precious family - Langston

* Edit: a few hours after making this post I surveyed the current Ortofon MM and MC cartridges and found that the 5.0mV and 0.5mV RMS voltages, respectively, are indeed reasonable assumptions of typical output levels. NAD's PP 2 designer knew what he was doing.
 
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JeffS7444

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So I'd expect the answer to your question to be "no"; pops and ticks will be reproduced cleanly.
Thanks for the detailed reply; it seems you got a heck of a deal on that NAD! Aside from the inconvenience, noise, expense and distortion, what's not to love about vinyl playback :p
 
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Langston Holland

Langston Holland

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I wonder if this is the same circuit as in my old NAD 3140.

Nope. I just looked. Found a service manual for your unit from a Croatian service center. The Internet is amazing..

Your unit apparently handles MM cartridges only*, but it also looks like a better circuit than the PP 2. The only way to be sure of course is to measure it, but it looks like a very good design.

NAD 3140 Phono Circuit Block Diagram
NAD 3140 Block Diagram.png


NAD 3140 Phono Circuit Schematic (ugly, but folks into this stuff can figure it out)
NAD 3140 Schematic.png


NAD PP 2 Phono Circuit Schematic (reverse engineered by a diyAudio guy, so there may be errors)
NAD PP 2 Schematic.gif


God bless you and your precious family - Langston

* Edit: this is right or wrong depending on the manual version you read. One says that the 10dB hotter PH 1 input will support "high-output" MC cartridges, but requires external amplification with "low-output" types, the other simply states external amplification (such as a MC step-up transformer) is needed.
 
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Rottmannash

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Nope. I just looked. Found a service manual for your unit from a Croatian service center. The Internet is amazing..

Your unit apparently handles MM cartridges only, but it also looks like a better circuit than the PP 2. The only way to be sure of course is to measure it, but it looks like a very good design.

NAD 3140 Phono Circuit Block Diagram
View attachment 155573

NAD 3140 Phono Circuit Schematic (ugly, but folks into this stuff can figure it out)
View attachment 155574

NAD PP 2 Phono Circuit Schematic (reverse engineered by a diyAudio guy, but it looks right)
View attachment 155575

God bless you and your precious family - Langston
It has 2 inputs- one for MM and one for MC as well as a slide switch for capacitance.
 
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Langston Holland

Langston Holland

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It has 2 inputs- one for MM and one for MC as well as a slide switch for capacitance.

I just found a manual for your unit and something unusual happened. I was right. Kinda. There's at least two manuals, one says no MC the other says high-output MC only. Whatever. : ) See the edit to my post on the NAD 3140 above.
 

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  • NAD 3140 Service Manual.pdf
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Rottmannash

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Cool. Ironically that page in my ancient manual has been torn out so that's helpful.
 

badboygolf16v

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Thanks for this review @Langston Holland, exactly what I need to go with my recently acquired Technics SL-7. Performance is good enough and is very reasonably priced. I got the PP2e.
 

BadAudioAdvice

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Thanks for this review @Langston Holland, exactly what I need to go with my recently acquired Technics SL-7. Performance is good enough and is very reasonably priced. I got the PP2e.

@badboygolf16v What cartridge are you using with your SL-7?

I bought an Audio-Technica AT85EP and it has been very problematic with my SL-7 - if there is static on the record, it creates *terrible* loud pops.

I haven't had time to do a deep investigation, but either I got a bad batch (I actually bought 2 AT85EPs at the same time - the other for my SL-10 - same problem), or there is a compatibility issue with the Technics SL-7/10 design.
 

badboygolf16v

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Mine came with a nearly new Ortofon OMP 5E.

From my limited research I think perhaps it may not be fully to T4P spec regarding tracking force, in that it requires more than the spec. I think recommended tracking force is 1.75g for my cart and T4P spec is not higher than 1.5g. I'm probably talking rubbish and any correction will be gratefully received.

Anyway, regardless, I've had no issues whatsoever with the handful of discs I've played so far. They were all in good nick, no warps and pretty well centered so yet to torture test it.

None of the issues you describe as yet.
 
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Hi, I wanted to know if in your opinion it is better to connect this phono preamplifier that I have (NAD pp2) or is it better to use the phono preamplifier integrated in my Technics SU C800?
the Nad pp2 has an 80dB snr ratio and the Technics 76dB
WhatsApp Image 2023-02-13 at 12.25.23 (2).jpeg

20230107_121859.jpg
 
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Salve ieri ho collegato il NAD pp2 con il nuovo alimentatore (sempre switching ma più potente 1 A) preso su amazon in quanto l'originale 0.1 A non funzionava molto bene causa presa deformata, nonostante questo non ho notato nuovamente grandi miglioramenti al preamplificatore phono integratore del preamplificatore Technics Su c800,for the connections I used homemade Mogami 2534 neglafex Quad cables, they should have capacity 97 pf/m

20230215_220209.jpg
 
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