Pro-Ject Phono Box DS3 B Review

[beeface]

I wonder when we'll see a product beat the Cambridge Solo on the SINAD chart?

I don't see how this gets the same rating as the Mani 2. So far as I can see, we have higher headroom at 45, pretty close at 60, higher headroom at all frequencies, lower sinad by a hair overall. Yet, this is $799 vs $149 for which you get some useful features, for some people. But 90% won't care about balanced and will set and forget the settings so the bottom facing adjustments aren't as big an issue either )).

I wouldn't get too wound up about the panther tbh, it's just a bit of fun

On that note, I just looked at Stereophile's recommended list out of curiosity. You have to scroll quite a bit before you find something in the three figure range

 

[PoorishDecision]

a waste of a balanced input, probably get better quality audio running 192k mps from the 3.5 jack from your phone. vinyl has always mystified me honestly

 

[AaronJ]

Not sure this can be compared to Schiit Mani because it’s a different beast. But can it justify costing twice the Schiit Skoll? Absolutely not. I considered one of these for a little while and have generally felt that Project gear is marked up around an additional 100% from where it should be. They make 39 different turntables not including the dozen or so special editions. Feels like IKEA of the turntable world.

 

[AaronJ]

a waste of a balanced input, probably get better quality audio running 192k mps from the 3.5 jack from your phone. vinyl has always mystified me honestly

People’s reasoning for writing these kind of posts will always mystify me to be honest.

 

[restorer-john]

Has anyone shown that high fidelity reproduction of pops and clicks, with all their high frequency energy, is audibly superior to clipping them at a lower amplitude? Passing a 100mV click @ 40dB gain is a 10V output from the pre-amp - that's going to be bloody loud if the power amp can pass it along unclipped to the speakers. 26dB louder than the recorded material at 5mV level. And there is a good chance of clipping in the power amp instead, depending on the listening level.

It's not a-priori obvious to me that a click of that magnitude wouldn't sound better if clipped to a lower amplitude, say 5V.

When you clip a phono stage, the result can be benign or dreadful, depending on how the stage reacts and/or recovers. Basically, the stage can no longer control via feedback the swing you ask it to deliver and it may latch-up, oscillate or take considerable time to stabilize after the overload event.

It's always better to have a huge overload margin in a phono stage. Most of the stages @amirm has tested are atrocious in that regard.

And how do you propose clipping the cartridge signal at a "lower amplitude" in the analogue domain without amplifying it first?

 

[PoorishDecision]

People’s reasoning for writing these kind of posts will always mystify me to be honest.

because this source device could get by using bluetooth or fm with no bottleneck at all, why waste a balanced input on this that could be used for a better source?

 

[Zapper]

When you clip a phono stage, the result can be benign or dreadful, depending on how the stage reacts and/or recovers. Basically, the stage can no longer control via feedback the swing you ask it to deliver and it may latch-up, oscillate or take considerable time to stabilize after the overload event.

Right. So let's say the amp is designed properly and recovers quickly and stably - not a particularly hard thing to design. Then why is that worse than an unclipped transient of enormous amplitude?

This has the flavor of a design preference based on an outdated concern. Once upon the time, op-amps exhibited the poor overload behaviors that you mentioned. It made sense to provide those amps with a lot of margin to keep them out of trouble. But now that there are amps with good recovery behavior, such margin may be unnecessary.

It's always better to have a huge overload margin in a phono stage. Most of the stages @amirm has tested are atrocious in that regard

Why is it better to have a huge overload margin? A huge overload margin means huge output transients are possible during pops and clicks. That seems to be a bad thing.

And how do you propose clipping the cartridge signal at a "lower amplitude" in the analogue domain without amplifying it first?

Who said anything about not amplifying it first? Not me.

 

[restorer-john]

Right. So let's say the amp is designed properly and recovers quickly and stably - not a particularly hard thing to design. Then why is that worse than an unclipped transient of enormous amplitude?

Why is it better to have a huge overload margin? A huge overload margin means huge transients are possible during pops and clicks. That seems to be a bad thing.

Who said anything about not amplifying it first? Not me.

This is a review thread, not a discussion of phono preamplifier design/topologies. By all means start a separate thread.

 

[Zapper]

This is a review thread, not a discussion of phono preamplifier design/topologies. By all means start a separate thread.

Makes sense. I'll do so tomorrow.

 

[audio_tony]

Why is it better to have a huge overload margin? A huge overload margin means huge output transients are possible during pops and clicks. That seems to be a bad thing.

Scratches etc. on the record create large transients, often much higher in level than the recorded music, which result in clipping in the phono stage resulting in distortion (the entire signal will be distorted once the stage clips).

Therefore, a good overload margin ensures that scratches etc. won't cause the phono amp to overload.

Additionally, the additional headroom and resultant lack of clipping means that the noises produced by scratches are less pronounced, as the phono amp is no longer being driven into clipping.

 

[JSmith]

Not too bad at all... thanks for the review @amirm.

Let's take a peek under the hood;

JSmith

 

[Zapper]

Scratches etc. on the record create large transients, often much higher in level than the recorded music, which result in clipping in the phono stage resulting in distortion (the entire signal will be distorted once the stage clips).

Therefore, a good overload margin ensures that scratches etc. won't cause the phono amp to overload.

Additionally, the additional headroom and resultant lack of clipping means that the noises produced by scratches are less pronounced, as the phono amp is no longer being driven into clipping.

You're begging the question - you are simply assuming the answer, which is that clipping is bad. I'm asking for evidence that a clipped pop or click signal of reduced magnitude sounds worse than a non-clipped signal of enormous 26dB+ magnitude (assuming the pre-amp overload recovery is fast and stable).

That's assuming that the rest of the chain has 26dB+ of headroom and won't clip either. If not, then clipping occurs in the power amp, which is likely worse than the pre-amp.

 

[Chagall]

because this source device could get by using bluetooth or fm with no bottleneck at all, why waste a balanced input on this that could be used for a better source?

To get rid of ground loops...and how is using input a waste if that is the source you need?

 

[audio_tony]

You're begging the question - you are simply assuming the answer, which is that clipping is bad. I'm asking for evidence that a clipped pop or click signal of reduced magnitude sounds worse than a non-clipped signal of enormous 26dB+ magnitude (assuming the pre-amp overload recovery is fast and stable).

That's assuming that the rest of the chain has 26dB+ of headroom and won't clip either. If not, then clipping occurs in the power amp, which is likely worse than the pre-amp.

At the risk of taking this review thread off topic...

Visualise a typical 'pop' or 'click' as a waveform. Without clipping, it's just a brief spike and the resulting sound is less obnoxious than the clipped (square wave) signal.

With regard to the rest of the chain and headroom, it will obviously depend on the listening levels, preamp input sensitivity etc.

But typically, a high overload margin in the phono preamp definitely leads to the pops and clicks being less offensive, regardless of the rest of the chain (within reason).

 

[Michael Fidler]

It looks quite good to me in terms of its RIAA performance, although it's a pity to see the HF response drooping. I have voted it FINE in recognition of the progress the company is making.

This graph characteristic is a classic sign of passive RIAA equalisation causing premature clipping. An overload margin of 10dB (3 times nominal 5mV level) at 20kHz really isn't going to cut it...

In my view, a balanced phono input is of limited use in practice, and not very sound from an engineering point of view. As the cartridge is a floating source, there is no possibility of creating a ground loop unless the turntable wiring is faulty. Adding a differential amplifier input increases the noise by 3dB at the very minimum compared to the single-ended variety. When you connect it to a generator you see an absence of hum, compared to a single-ended input where there may be a loop through the generator. In this case we see an MC SINAD of 60dB... It's a very nice marketing story, but further investigation reveals that it can hurt considerably more than it helps. There are a few more reasons, and I should really compile these into an article with considerably harsher analysis.

 

[AaronJ]

because this source device could get by using bluetooth or fm with no bottleneck at all, why waste a balanced input on this that could be used for a better source?

Because people like to listen to vinyl. Your type of post exists in basically every thread in this sub forum. Are those reading your post supposed to say to themselves, “Shucks this guy is right I never thought about it that way”? All you’ve done is attempted to derail a thread (successfully I’ll add) and exposed your own insecurity and discomfort about people liking something you don’t.

 

[Michael Fidler]

When you clip a phono stage, the result can be benign or dreadful, depending on how the stage reacts and/or recovers. Basically, the stage can no longer control via feedback the swing you ask it to deliver and it may latch-up, oscillate or take considerable time to stabilize after the overload event.

It's always better to have a huge overload margin in a phono stage. Most of the stages @amirm has tested are atrocious in that regard.

And how do you propose clipping the cartridge signal at a "lower amplitude" in the analogue domain without amplifying it first?

Schottky diodes with positive bias perhaps? The effect will be much the same! In this case, the clipping will most likely be occurring in the first stage before RIAA equalisation. So intermodulation products from clipping at 20kHz due to surface defects are going to be boosted up by 20dB at 1kHz, and 33dB at 100Hz. These assymetrical artefacts (see how a click/pop waveform contains HF content in one direction) will create far more noticeable artefacts where we will actually hear them as a result...

This is why passive RIAA equalisation is such a poor choice. If an active network clips, then the distortion products don't get equalised as the amplifier output that clips has already undergone equalisation.

 

[Zapper]

When you connect it to a generator you see an absence of hum, compared to a single-ended input where there may be a loop through the generator. In this case we see an MC SINAD of 60dB... It's a very nice marketing story,

Good point, but in addition to marketing it's also an example of design-to-test. The designer is graded by how well the pre-amp performs on the audio analyzer. We see Amir's tests of phono pre-amps often show mains hum - hum that in many cases might go away with a floating cartridge on the input - and Amir and his audience rates such devices poorly. The diff amp helps it test well on the analyzer and get a better panther rating.

 

[Michael Fidler]

Good point, but in addition to marketing it's also an example of design-to-test. The designer is graded by how well the pre-amp performs on the audio analyzer. We see Amir's tests of phono pre-amps often show mains hum - hum that in many cases might go away with a floating cartridge on the input - and Amir and his audience rates such devices poorly. The diff amp helps it test well on the analyzer and get a better panther rating.

Unfortunately you're quite correct. It's very difficult to exclude hum when measuring some 60dB at 50Hz with an analyser... For this reason I prefer to make noise measurements with a floating cartridge load box (with ground wire isolated, but going to the enclosure screening) to simulate the performance with a real TT. Based on the voltage noise only (low impedance analyser input) SINAD of this product, we might expect a practical SNR as low as 75dB with an MM input.

That and my current analyser being near useless for efficient development!

 

[aagstn]

I still occasionally buy a record and I don't even have a player. Usually buy straight through the artist's own shop. I don't listen to it, but I like the artwork and supporting the artist.

I have a few indie bands I support on Bandcamp. I like that you get the digital files in FLAC as well, so using the vinyl record is optional. Some small artists have stopped even offering a CD option so records are it if you want something physical.