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Proprius / Tannoy Stirling TW Speakers

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jwatson View Drop Down
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    Posted: 31 Oct 2017 at 6:16am
Hello All,

Does anyone have any experience driving Tannoy Stirling TW Speakers with Proprius amplifiers?  Maybe someone involved in the loaner program has heard some feedback from other users?

Tannoy recommends an amplifier in the range 30-150W but I used to drive them quite happily with a couple of flea powered SET amplifiers that I made.  A house move at around the time that I was losing interest in valve amplification meant that they've never been set up again.  I've been happy with the Solo Ultra-Linear DE headphone amplifier and prefer headphones for a lot of music.  However, for some of the more acoustic-based music, it would be nice to be able to play on speakers occasionally.


"I bought some more old vinyl today 'cos old vinyl won't ever let you down"
Majestic DAC -> Solo UL -> HD650
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 31 Oct 2017 at 8:05am
I'll let others comment on the sound but I can do the workings out for you.

Nominal impedance is 8 Ohms dipping to 5.5 Ohms. Therefore the Proprius can drive them.

At 8 Ohms the maximum output will be 25 RMS watts. This gives a raise in SPL (sound pressure level) of 14dB.

The sensitivity is quoted as being 93dB (for 2.83 volts which is 1 watt into 8 Ohms). Add the 14dB giving 107dB at 1 metre in front of each speaker.

Add 3dB because there are two speakers, makes 110dB at 1 metre.

If your speakers are set apart by the accepted 2 - 2.5 metres for stereo imaging, you will be sat at the third point on an (imaginary) equilateral triangle, and so will be 2 - 2.5 metres away. Let's set that at 2.5 metres.

Sound pressure loss is 6dB per doubling of distance, so at 2.5 metres the loss is 8dB.

Therefore you will experience 110dB - 8dB = 102dB SPL at full Proprius output. That is very loud for most people.

If the Proprius is turned down to 1 watt output, the rated sensitivity (again) is 93dB plus 3dB because there are two, making 96dB. The output at your seated position would therefore be (96dB - 8dB) 88dB - a realistic volume.

Speaker manufacturers quote minimum power to minimise the possibility of clipping which damages drive units. A low powered amp when called upon to deliver a high output will try to exceed its power supply voltage if pushed that hard. It is that which is called clipping.

If operated near to 88dB (you can get a sound pressure level app for your phone) then on 14dB transient peaks which are common in music, the Proprius will be (just) below clipping.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jwatson Quote  Post ReplyReply Direct Link To This Post Posted: 31 Oct 2017 at 1:07pm
Hello Graham,

Thanks for such a detailed response.  I'm not too worried about getting sufficient volume from the speakers as I'll probably be using them for acoustic-based Irish traditional music at reasonable levels and they worked very well with a small SET amplifier that I made a number years ago.  They sounded great but the valve amplifiers made everything sound equally warm and cosy.  I've heard stories about a Tannoy 'honk' that can manifest itself with certain amp/speaker combinations.  I've never had a problem with the speakers themselves so can't describe it further but was just wondering if anyone had reported problems with Proprius amps.  The speakers are wonderful and it seems a bit of a shame to have them sitting idle apart a bit of a waxing now and again to keep the wood seasoned in the very dry climate here.
"I bought some more old vinyl today 'cos old vinyl won't ever let you down"
Majestic DAC -> Solo UL -> HD650
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 31 Oct 2017 at 5:30pm
See "Returns Under Distance Trading Regulations" at https://www.hifisystemcomponents.com/services/returns.html
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Post Options Post Options   Thanks (1) Thanks(1)   Quote morris_minor Quote  Post ReplyReply Direct Link To This Post Posted: 31 Oct 2017 at 7:28pm
I use my Proprii in a music/AV system powering some PMC Gb1i speakers (87dB @ 1w/1m) and they go plenty loud enough for the biggest orchestral climax or blockbuster explosion. They've never missed a beat, and with Graham's Spatia speaker cables (and links) sound stunning. Who needs megawatt amps anyway except those who boast about the numbers? 
Bob

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
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jwatson Quote  Post ReplyReply Direct Link To This Post Posted: 01 Nov 2017 at 12:00pm
Hello Bob,

Thanks for the advice.  I'm not particularly worried about reaching acceptable volume levels as the SET amplifiers I made were around 7W maximum output and they were perfectly loud enough for my small lounge.  For some types of music (particularly electronic/industrial) I prefer headphones as I'm not seeking to reproduce a real instrument - the 'instruments' are abstract and don't exist outside of a computer; the 'inside the head' phenomenon can often add to the listening experience.  However, for acoustic and Irish Traditional music I'm more interested in faithfully reproducing the sound of a real instrument so am looking to dig out the speakers again.

I've seen occasional references to a Tannoy 'honk' when the speakers are used with some amplifiers, I've never heard it myself so am unable to describe it directly.  However, given Graham's reputation, I'm sure that this won't be a problem but it seemed sensible to ask the advice of people that may have been involved in the loaner program and maybe have some anecdotal reports from people that have tried the amplifiers with the Tannoys.

I'm ok for cables and have some van Den Hul SCS-4 cables that were custom made in the factory for someone unable to use a tape measure and for whom the phrase 'bend radius' meant nothing.  I happened to be in the shop as he was trying to return them and took them off his hands for a fraction of what he's paid for them a month earlier :-) For the interconnects I'll make my own if I can source decent connectors locally or otherwise spring for the Librans.  

It looks like I'll be placing an order in the next couple of days...
"I bought some more old vinyl today 'cos old vinyl won't ever let you down"
Majestic DAC -> Solo UL -> HD650
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