Review and Measurements of u-turn Pluto and ART DJPRE II Phono Preamps

[amirm]

What kind of battery?

 

[P_M]

Any kind. But mostly I have seen people use the smallest sla they can find. I have this pre and currently I am just temporarily using my own experimental apparatus of a 9V battery with 2 AAs in series, which I am going to soon make it more permanent with something like this -
https://www.amazon.com/gp/product/B07HFPCX9V/ref=ox_sc_saved_title_1?smid=A1NE7EP7NCJCJH&psc=1
or this
https://www.amazon.com/gp/product/B07NSQB41B/ref=ox_sc_saved_title_2?smid=A1U5UA161KZZJJ&psc=1

 

[audiopile]

I've tried 12V SLA batteries compared to wall worts on the ART DJ Pre II - never measured -but don't hear any difference. I've given away a bunch of these - they rate the cheapskate evil grin award- way better than the 50 bucks I've spent on them. They are reasonably quiet and revealing enough that I have no problem hearing the difference between my various MM/IM carts. Not perfection - just really good -amazingly good for 50 bucks. I think the bright blue light just shows it's pro-audio origins - any of us who have done live sound live in fear of the unplugged anything . So -ya can't miss the lights on the ART DJ pre II - guess it's lit up ugly- but you can tell if it's on or clipping from across the room and that's probably not accidental.

 

[P_M]

@amirm Can your test equipment do IMD tests ? If so it would be great to see IMD tests of any amp (phono, headphone, power, pre) , especially over a frequency range.

 

[amirm]

@amirm Can your test equipment do IMD tests ? If so it would be great to see IMD tests of any amp (phono, headphone, power, pre) , especially over a frequency range.

Sure. I will add it to future tests.

 

[Deacon Blues]

Is there a way to get the pluto power bleed out? Is there a replacement supply that I can get for it that will perform better? Or is money better spent on a better phono preamp? If so, which has the highest SINAD?

 

[audiopile]

BTW- the really remarkably cheap price of the ART DJ Pre-II (BTW- has it now -after many years- gone up to $65 ? - tariff increased price probably ?) makes it reasonable to compare whatever mod turns your crank on one unit with a stock unit -without depending on the always questionable "audio memory" . I've never used one with a SUT -but suspect that the clipping indicator/gain level pot feature would be very useful in detecting and dealing with one of the potential pitfalls of SUT use - overdriving MM inputs (which sounds REALLY nasty).

 

[oldmanhifi]

I bought one of these to give it a try and have been very impressed! I also had a 12V 7ah SLA sitting around that I use to power a go-to telescope mount. The cable from the battery to that mount included a plug compatible with the DJ Pre II. I have it powering the DJ Pre II and it is dead silent. The DJ Pre II got rid of the 100-200 "hump" that was very evident when using my Vincent PHO-8 with my AT VM95ML cartridge. That hump warmed up some thin sounding carts, but just "muddied" the sound of the AT. Measuring sound levels of pink noise (HiFi News and RR test record) at the listening position with my iphone (with FFT app) shows a remarkably flat in-room response. I have it set for 100 pf capacitance and the "rumble" filter on. I think the filter effect above 19khz also has an impact on reducing the perceived level of "clicks and pops" as well by attenuating the HF portion.

 

[hyperplanar]

I have an ART DJPRE II that I bought used because of this review. Is running it at the lowest possible gain level worth it in terms of the tradeoff of SNR for increased headroom to accommodate clicks/pops without clipping? Or will it clip anyways at the input stage before the gain is applied? Does the clipping indicator light up if the input stage clips, or only the output stage?

The output level is not of any concern to me, I have it connected to a Babyface Pro so I can simply apply digital gain, and the Babyface's input SNR is much better than the phono preamp anyways. Just interested in extracting the maximum possible performance out of this unit.

 

[P_M]

In the first post of the thread Aamir tested it with 5mv input, gain at "0" (center), and measured 22mv clipping. Thats pretty pathetic in my opinion. Its unclear whether the indicator turned red as well or not at that point. Because the mfg spec says max input level is 40mv.
So my guess is the indicator turns red when its already too late and if you hope to avoid compression even on quick short spikes you should set the gain below 0 - maybe at the -1 or -2 setting.

 

[Jim85IROC]

Is there a reason this shows a "no" in the Recommended column in Amir's review list? Based on the review here, it appears that it is recommended.

 

[P_M]

Good question. My guess is due to the anamolies in low frequency response , and low headroom(22mv).

 

[twozeroseven]

Looks like U-Turn has a second generation Pluto ("Pluto 2", conveniently). Among other changes, they list a "redesigned power supply" that may have solved the power supply noise Amir identified. Given I prefer the aesthetics of the Pluto 2, I think I'll give it a go.

https://uturnaudio.com/pages/introducing-pluto-2-phono-preamp

 

[Jim85IROC]

My ART DJPRE arrived yesterday. I haven't listened to anything that I'm actually familiar with, but so far I'm satisfied. Right now I'm listening to a very poorly recorded live Fleetwood Mac concert with a massive noise floor on a very dirty, warped record.

 

[ArtDJ]

Not really understanding the phase shift issue. Can someone please explain it and describe how it affects what you hear?

 

[P_M]

if I am not wrong, unwanted phase shifts cause nulls and peaks in the listening space. It would sound like a certain frequency or range of frequencies are sucked out or over emphasized. In bass it could be too boomy or lack of bass. It also destroys depth soundstage and imaging although for low frequencies (<100hz) that shouldn't matter much.

 

[pozz]

Is there a reason this shows a "no" in the Recommended column in Amir's review list? Based on the review here, it appears that it is recommended.

I put together the review database for electronics. When Amir and I discussed how to list entries for reviews, he said that anything which isn't an unhedged or unqualified yes should be a no. The only time this has changed is when he started adding his EQ decisions to the recommendations, so a second column was added to the headphone review index.

But if you see other weird stuff like that, please message me. I'm sure I've made the occasional mistake.

 

[Dimitrie94]

Conclusions
The ART DJPRE II is a great bargain here. Other than some strange phase shift at low frequencies and lower input dynamic range, it actually beats the more expensive u-turn Pluto in the rest of the measurements.

The main fault I see with the Pluto is the power supply noise. A bit more attention there could have easily landed it on top.

Both are great bargains from what I can see. Personally I find the DJPRE II a more flexible unit so if I had to buy one, it would be that if I could hide it some place.

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As always, questions, comments, corrections, etc. are all welcome.

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Hello from Romania,
I used the frequency sweep from the Hi-Fi News Test LP and scanned the sweep with the Analyse plot tool in Audacity and found no significant high cut, also checked with the Phase analysis tool in Adobe Audition 2017 and found no obvious anomalies with the phase. So what other software can I use to analyse and expose such deficiencies ?

Do you believe that Schiit Mani is vastly superior to the ART DJ Pre II, like stated by HiVinyws channel ?

In the following video I couldn't see the difference, can you highlight it for me ?

 

[Lttlwing16]

I've tried 12V SLA batteries compared to wall worts on the ART DJ Pre II - never measured -but don't hear any difference. I've given away a bunch of these - they rate the cheapskate evil grin award- way better than the 50 bucks I've spent on them. They are reasonably quiet and revealing enough that I have no problem hearing the difference between my various MM/IM carts. Not perfection - just really good -amazingly good for 50 bucks. I think the bright blue light just shows it's pro-audio origins - any of us who have done live sound live in fear of the unplugged anything . So -ya can't miss the lights on the ART DJ pre II - guess it's lit up ugly- but you can tell if it's on or clipping from across the room and that's probably not accidental.

I own the Art DJ PreII as well, and with the very recent purchase of the THX 789, AEON RT's and GRACE BALANCED DAC, I was considering if I need to upgrade my preamp/cartridge to come up to the fidelity of the previously mentioned. I briefly owned a 789 (had to return it d/t volume pot issues) and it had a noticeable ground loop with the DJ Pre II when I had it connected via RCA.

That said, I was doing some research and some said the Schiit Mani with (http://www.swagmanlab.com/Product_PSU?product_id=670) linear power supply was a great combo. Then I looked into using a linear supply with the ART Dj PREII to help quelch the ground loop, and came across the discussion here and a post on reddit where the guy used a $22 bench power supply from parts-express, with some adapters. Not sure the fidelity of a bench power supply?? All that said, I'd assume the ground loop would disappear with a better power source than the included wall wart. As far as the sound, I'm relatively pleased with the ART/AT3600L combination on my SL-23 and not sure I want go down the rabbit hole of chasing marginally better sound.

However, if the alternate power source would help, I'd be open to even considering one of the one's from swagman.

 

[audiopile]

What exactly are the issues with a ground loop you are having ? I have decades of experience chasing/cursing ground loops in analog systems - but classic trouble shooting for ground loops in phono systems involves both removing or adding grounding until the hum goes away. How do you know the hum/loop is being caused by the power supply on the ART ? Not trying to attack you-but lots of us have dedicated large chunks of our life to attacking this issue from the wrong end- no matter how often you do it -it 's not a "boy-can't wait to do that again" experience. Tell us what you are using and what you have tried to reduce the hum ? Personally-doubt a power supply will make adifference on the ART DJ Pre II ?