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Proprius Amp with Harbeth M30.1

Printed From: Graham Slee at Hifi System Components
Category: And the rest
Forum Name: Amplification
Forum Description: Share your interests or views on amplifiers, preamps, etc
Printed Date: 11 Jul 2020 at 6:15am
Software Version: Web Wiz Forums 12.01 -

Topic: Proprius Amp with Harbeth M30.1
Posted By: joe-siow
Subject: Proprius Amp with Harbeth M30.1
Date Posted: 20 Sep 2019 at 6:53am
Hi everyone, I am currently amp shopping and would love the advice of the fine members here.
My room size is around 3 meters by 4 meters and I am currently running a digital streaming setup with the SoTM SMS200 streamer to Chord Qutest DAC, speakers is Harbeth M30.1. If I do go for the Proprius, I will have to use RCA to XLR adapters as the Qutest DAC only has RCA output.
I previously had the Leben CS300XS tube amp but the 15 push/ pull watts was simply not sufficient to drive the 30.1.
I understand that Graham designed the Proprius with the Harbeth 20.1 as one of his tuning speakers. Is anyone currently using the Proprius with the 30.1? Do you feel that the 30.1 is too hungry for the Proprius?
Thanks for any feedback!

Posted By: Graham Slee
Date Posted: 20 Sep 2019 at 8:02am
It depends on their use. For "normal" listening where the speakers and you are positioned for optimum stereo - speakers set 2m - 2.5m apart - then you'll be on the "first watt" most of the time, and the remaining 24 watts are there for effortless transients.

But the M30.1 is 6 ohms so the Proprius will deliver more than 25 watts, nearer 32 watts, which the 125 watt power supply is quite capable of.

Harbeth's own amplifier recommendation is "suggested from 25W", and here you have 32.

For hotel reception room use one customer uses a pair with high sensitivity speakers, so John C went along out of curiosity. When I asked if they were loud enough, he said "loud? When I left I could still hear the music in the car park across the street"

It looks like your source is fixed line output. Hopefully it can be set to a reasonable voltage? I read it outputs 3V which is rather high, and although the Proprius balanced input stage has good latitude, 3V uses up 14dB of its headroom. It would be sensible to operate it nearer its 575mV sensitivity.

With 0dBFS adjusted for 575mV on its input, the Proprius volume control fully clockwise, full power is delivered to the speakers, and there should be no clipping. I would not recommend using it like this unless you're in a sound proofed room and want disco levels.

Remember, the Proprius volume controls aren't like regular hi-fi amplifier volume controls which are set for maximum out at 12 0'clock (seems like cheating to me). The Proprius volume controls use their full span.

Not simple enough for Google-Bot to understand...

Posted By: joe-siow
Date Posted: 21 Sep 2019 at 4:05am

Appreciate the advice Graham! It is extremely helpful.

I can select the voltage output of the Qutest DAC; 1, 2 or 3V.
The Qutest DAC only has RCA output, so I will have to use RCA interconnect. My other question is: Would it be a degradation to sound quality should I use a RCA to XLR adapter below? -

Posted By: Graham Slee
Date Posted: 21 Sep 2019 at 7:39am
I'd have expected more replies for you but I guess there are a lot of distractions going on in the world right now keeping our members otherwise occupied.

The 1 volt output will be fine. Adjust the Proprius volume controls accordingly.

The adaptor will work...

...interesting marketing claims: I wouldn't consider brass to be eutectic as zinc melts at a lower temperature than the brass alloy; it looks to be a Neutrik NC3MX which has a black chromium finish over the diecast zinc shell; the phono socket looks just like the Maplin ones I used to buy; and if so, we made one just like it but I didn't like all the wire it takes inside to take up the twist of screwing the modified "strain relief" on... -

(nice bit of printed heatshrink though)

We also make unbalanced interconnects available with a choice of plugs including the same Neutrik plug. - -

Not simple enough for Google-Bot to understand...

Posted By: Aussie Mick
Date Posted: 21 Sep 2019 at 9:44am
Hi Joe,
   There are many members here who can attest to the effectiveness of Slee cables. I’ve had a few “high end” brands and they do not work as well as the Spatia and Lautus cables made for me by this wonderful company. Furthermore, they will make exactly the cable you need, to the exact lengths you need, without fuss.
Anyone else care to weight in?

Rega RP8/Ortofon 2M Black/Rega Apheta 2 - Reflex M/Elevator EXP - C.E.C. TL5 CD Transport - MacBook Pro/Roon - Majestic DAC - Solo ULDE (Focal Elear) - Proprius - PMC Twenty5.22

Posted By: Fatmangolf
Date Posted: 21 Sep 2019 at 3:25pm
GSP/HFC are the best cables I have heard and cheaper than several I sold on from well reviewed brands.

My Proprius amps have worked well in a similar sized room at the listening distances Graham noted. Sounded great and able to go very loud with different sensitivity speakers from 83dB to 91dB per watt. Hope that helps.


Open mind and ears, whilst owning GSP Genera, Accession, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.

Posted By: BackinBlack
Date Posted: 21 Sep 2019 at 5:10pm
I would recommend either CuSat or Lautus interconnects rather than an adaptor. When ordering you can request RCA to XLR terminations tailored to suit the Proprius input.

Mention should also be made of the Loan Scheme which allows you to listen to all Grahams products in the comfort of your own home for a week or so.

Happy Listening

Just listen, if it sounds good to you, enjoy it.

Posted By: morris_minor
Date Posted: 22 Sep 2019 at 7:51am
My two-pennies worth - I have Proprius amps driving PMC floorstanders: plenty loud enough for any music and blockbusting movies. Connected with Spatia cables, and with Graham's interconnects in the system too. Couldn't want for more!


Majestic DAC/pre-amp
Accession MC/Enigma, Accession MM, Reflex M, Elevator EXP, Era Gold V
Solo ULDE, Novo, Lautus USB and digital, Libran balanced, CuSat50
2 x Proprius + Spatia/Spatia Links

Posted By: Ash
Date Posted: 22 Sep 2019 at 8:07am
If in doubt, loan it out.

You only pay outward and return postage.

Posted By: joe-siow
Date Posted: 22 Sep 2019 at 9:10am
Many thanks to everyone for the advice. Very lovely to see you guys share your opinions

A home loan would not be quite possible at this point as I am in Singapore

Shall do more reading as I try to make a decision soon

Thanks all!

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