Muse phono stage

[djb]

An easy access compendium for all Muse phono stage related posts so I can find them currently they are too dispersed under non relevant headers and I tire of redirecting ppl who PM me. This is not a commercial build there are only 3 of them! V1 was never built.

Perhaps Andrew could begin us with a few key documents before others chime in.

Edited August 18, 2013 by djb

[cheekyboy]

Will be watching with interest, David....................hope this is not taken as a chime!

[Willco]

Yes Indeed I have been following the Andy's thread with interest also-- the Skeletal LP12 is looking and I believe  sounding excellent

 

Likewise I'd be interested to hear the glowing reports of the Muse Phono stage--only 4 in existence I see.

 

Willco

Edited August 18, 2013 by Willco

[metal beat]

I have heard Andy's MM battery phono stage.      

 

Despite my reservations about the dynamics with battery phono stages, it sounded excellent   and did not seem to be shy in dynamics.    

 

 For me at the time was a little low in output for my 1.2mv mm.  That low output is unusual and not the norm and is perfectly fine for the normal 3mv and above mm's.  I would like to hear it again at some stage coupled with an active head amp or SUT.

[andyr]

I have heard Andy's MM battery phono stage.      

 

Despite my reservations about the dynamics with battery phono stages, it sounded excellent   and did not seem to be shy in dynamics.    

 

 For me at the time was a little low in output for my 1.2mv mm.  That low output is unusual and not the norm and is perfectly fine for the normal 3mv and above mm's.  I would like to hear it again at some stage coupled with an active head amp or SUT.

 

Hi Shane,

 

Yes, that one (which djb owns now) was 'normal' 40dB MM gain.  With this latest one, I was able to get more gain by changing the make-up of the gain stages and using different JFETs.  So it has 55.5dB gain - which copes fine with my 0.28mV Benz LP (so will certainly deal with your 1.2mV MM without the need for a step-up  ).

 

 

Regards,

 

Andy

Edited August 18, 2013 by andyr

[Batty]

56dB is a good number, I found with my hagerman bugle 2 (a different league I know) that 60dB was way too much and 50dB too low for my VdH DDT-II which is 0.65 mV at 5cm/sec

[andyr]

Yes Indeed I have been following the Andy's thread with interest also-- the Skeletal LP12 is looking and I believe  sounding excellent

 

Likewise I'd be interested to hear the glowing reports of the Muse Phono stage--only 4 in existence I see.

 

In my case I own two of these Stages--there are only 6 in the world 2 are 230V

 

Willco

 

 

Googling it, Wilco, I see that although it is a John Curl design ... it appears to incorporate at least one opamp in the circuit?  As such, I believe its sound quality may very well be able to be surpassed. 

 

Re. your comment "I see there are only 4 (Muses) in existence" - not quite.  v4 (the one in Tasmania) is the latest version.  This has a couple of changes over v3 - which djb owns.  v3 had a couple of changes over v2 ... v2 was the first one I built that I considered was "acceptable" - and Graham ('gamve', in Tasmania) bought this from me 3 years ago.  Graham supplied me with the circuit (which originally came out of an 80s electronics magazine) 4 years ago but when I built this original circuit (ie. v1), I found it had an unacceptably rolled-off RIAA response.  So I spent the next 12 months researching the equations which govern RIAA and then produced v2.

 

So there are only 3 Muses in existence, so far.

 

 

Regards,

 

Andy

[andyr]

An easy access compendium for all Muse phono stage related posts so I can find them currently they are too dispersed under non relevant headers and I tire of redirecting ppl who PM me. This is not a commercial build there are only4 of them!

Perhaps Andrew could begin us with a few key documents before others chime in.

 

Thank you David,

 

The background and basic specs of the 'Muse' phono stage are as follows:

 

Background:

 

This circuit uses the classic tube phono stage configuration of a passive composite RIAA network sandwiched between 2 gain stages – except that, in this case, the gain stages are JFETs not tubes.

 

Being battery powered, it is extremely quiet; the 55dB gain makes it suitable for LOMCs from 0.28mV (eg. Benz Ebony LP) as well as HOMMs (eg. Grado Reference Reference1).

 

The circuit concept was originally put forward in the late ‘80s (the “Pacific RIAA Preâ€), however, 4 years of R & D – including the addition of Allen Wright’s 50KHz RIAA boost – has turned the original circuit into something quite different.

 

 

Specifications:

• Battery powered (2 x 12v, 1.3AH SLAs per channel).
• Hand matched, discrete JFETs & transistors.
• Dual mono construction.
• Point to point wiring, using a Teflon “circuit board†to hold the components in place.
• Ground plane earthing.
• 55dB gain
• Single-ended, class A, zero global NFB.
• Passive RIAA (1% resistors and hand matched polystyrene caps in RIAA circuit).
• Output impedance approx 25 ohms.
• 100K input load resistance (use load plugs with an 89K res installed to reduce this to 47K).
• 110pF input load capacitance.
• 2 pairs of parallel input RCA sockets, for simultaneous ‘R’ and ‘C’ load setting.

 

Some pics are attached.

 

 

Regards,

 

Andy

[metal beat]

Andy

 

That is a BIG knob you have there 

 

It has changed a bit for V4 

[gamve]

Googling it, Wilco, I see that although it is a John Curl design ... it appears to incorporate at least one opamp in the circuit?  As such, I believe its sound quality may very well be able to be surpassed. 

 

Re. your comment "I see there are only 4 (Muses) in existence" - not quite.  v4 (the one in Tasmania) is the latest version.  This has a couple of changes over v3 - which djb owns.  v3 had a couple of changes over v2 ... v2 was the first one I built that I considered was "acceptable" - and Graham ('gamve', in Tasmania) bought this from me 3 years ago.  Graham supplied me with the circuit (which originally came out of an 80s electronics magazine) 4 years ago but when I built this original circuit (ie. v1), I found it had an unacceptably rolled-off RIAA response.  So I spent the next 12 months researching the equations which govern RIAA and then produced v2.

 

So there are only 3 Muses in existence, so far.

 

 

Regards,

 

Andy

 

So There are only 3 Muses in existence so far. Sorry Andy had to chuckle at this as have 3 three of them are here in my stereo room as I type this..This

includes my original build, so the only one I have not heard is V3.

 

Chris and I spent yesterday afternoon swapping and listening to the Muse V4 against his Herron phono stage. We were time limited and did not play with

the loading plugs on the V4. My comments relate to this quick and nasty first impression listening with little set-up and optimising. The turntable was my

old trusty and highly underrated Pioneer PLC590 with a FR54 arm and a ZYX Airy III. I will set up the Muse V2 with the ZYX CPP step up later this week and compare

this unit against the V4. I will also retrieve my ZYX Artisan out on loan to a friend and run this as well. 

 

Must say Andy that the new case is very nice. I love the battery check sockets on the front where they are easy to get at. The switching arrangement is very nice

to use, certainty makes the Muse V2 look and feel a bit clunky   The rear is  intuitive and beautifully set out with everything nicely spaced and positioned.

The extra gain is a most welcome addition for MC users. Can the new circuit still cater for MM cartridges with easy modification? Personally I would think it would be a

shame to lose the MM capability.

 

I hooked The V4 up earlier last week for an initial quick listen. I charged it for a few hours first but noticed the voltages were still below Andy's advised 24V. Still had a quick listen then hooked up the charger to charge overnight. After charging overnight I sat down for a good listen. I played a variety of music from classical, folk, jazz and rock. My first impressions are that the Muse 4 is one very capable and very refined phono stage.

 

As I mentioned Chris and I spent a very wet and windy Saturday afternoon listing to a variety of music styles using both the Herron and the Muse V4 stages. My personal preference was for the Muse V4 as I felt it sounded alive and lit up with great tone, nice frequency extension, appropriate pace/timing and dynamics. I

also liked the Herron with the FET input stage and the valve amplification stage. I did think the Herron was a bit dark and recessed sounding with a touch too much

bloom which I found a bit artificial. I think Chris basically agreed with my assessment of the sound quality but being used to the sound of his machine he was happy

with the more tube type sound. 

 

I'm not sure what Andy's plans are for this unit and if he is indeed interested in making these for others. I did here a figure somewhere and If the figure I heard is

correct then the Muse V4 should achieve great things.

 

Andy deserves the highest praise for developing this fine unit. I know he has spent countless hours sorting out issues with the circuit design and turning a basic rough working design into a refined world class unit. 

[andyr]

Andy

 

That is a BIG knob you have there 

 

It has changed a bit for V4 

 

Haha, yes Shane.  That is a beautiful ebony knob made by Duc (lovetube).     When Vince listened to v3 (after you sent it up to him, last year), he liked it but said he would only take one if I improved the aesthetics:

• changing the toggle switches on the front to a rotary switch with a knob, and
• putting it into a smaller case.

So this I was able to do; wiring the rotary switch (for charging the batteries & 'play') was a bugger ... but eventually I got it done!

 

 

Regards,

 

Andy

[andyr]

 

 

Thanks for this preliminary review, Graham - I have interspersed some comments amongst your text:

 

So There are only 3 Muses in existence so far. Sorry Andy had to chuckle at this as have 3 three of them are here in my stereo room as I type this. This

includes my original build, so the only one I have not heard is V3.

 

Ah, yes, I excluded that one as I didn't build it.   v3, as auditioned by a number of people, sounds better than your v2 ... but not as good as v4.

 

Chris and I spent yesterday afternoon swapping and listening to the Muse V4 against his Herron phono stage. We were time limited and did not play with

the loading plugs on the V4. My comments relate to this quick and nasty first impression listening with little set-up and optimising. The turntable was my

old trusty and highly underrated Pioneer PLC590 with a FR54 arm and a ZYX Airy III. I will set up the Muse V2 with the ZYX CPP step up later this week and compare

this unit against the V4. I will also retrieve my ZYX Artisan out on loan to a friend and run this as well.

 

I look forward to hearing your comments - also, I hope, a comparison against your Vitus,  

 

Must say Andy that the new case is very nice. I love the battery check sockets on the front where they are easy to get at. The switching arrangement is very nice

to use, certainty makes the Muse V2 look and feel a bit clunky   The rear is  intuitive and beautifully set out with everything nicely spaced and positioned.

The extra gain is a most welcome addition for MC users. Can the new circuit still cater for MM cartridges with easy modification? Personally I would think it would be a

shame to lose the MM capability.

 

Yes, I have used it with both my 0.28 Benz and my 4mV Grado.  You just have to turn the preamp volume control down a bit, when using an MM.

 

I hooked The V4 up earlier last week for an initial quick listen. I charged it for a few hours first but noticed the voltages were still below Andy's advised 24V. Still had a quick listen then hooked up the charger to charge overnight. After charging overnight I sat down for a good listen. I played a variety of music from classical, folk, jazz and rock. My first impressions are that the Muse 4 is one very capable and very refined phono stage.

 

As I mentioned Chris and I spent a very wet and windy Saturday afternoon listing to a variety of music styles using both the Herron and the Muse V4 stages. My personal preference was for the Muse V4 as I felt it sounded alive and lit up with great tone, nice frequency extension, appropriate pace/timing and dynamics.  I also liked the Herron with the FET input stage and the valve amplification stage. I did think the Herron was a bit dark and recessed sounding with a touch too much bloom which I found a bit artificial. I think Chris basically agreed with my assessment of the sound quality but being used to the sound of his machine he was happy with the more tube type sound. 

 

I'm not sure what Andy's plans are for this unit and if he is indeed interested in making these for others. I did here a figure somewhere and If the figure I heard is correct then the Muse V4 should achieve great things.

 

Andy deserves the highest praise for developing this fine unit. I know he has spent countless hours sorting out issues with the circuit design and turning a basic rough working design into a refined world class unit.

 

Thank you, Graham.  I certainly didn't anticipate when you sent me the original circuit that it would condemn me to several years of R&D! :lol: 

 

Regards,

 

Andy

Edited August 18, 2013 by andyr

[Willco]

Sounds an Exciting product indeed!

 

You mentioned the 80's design basis-- The finest Phono stage I've ever encountered was a listening session with the "Trinidad Connection" Lionel Seemungal and Walter Yips Passive RIAA  unit in the late 70's/early80's.

 

Good Luck  and keep up the great work

 

Willco

Edited August 18, 2013 by Willco

[Willco]

Googling it, Wilco, I see that although it is a John Curl design ... it appears to incorporate at least one opamp in the circuit?  As such, I believe its sound quality may very well be able to be surpassed. 

 

Regards,

 

Andy

 

Morning Andy, 

 

I asked John Curl for his comments

 

A --On where his Opamp was situated  and its purpose  plus for his views on your Phono.

 

Well Boyo take a Bow!--his exact words were  " The phono preamp described is a very good one"--Kudos from the Legend himself--Woooo!

 

B; His explanation re the Opamp-- "However, the OP's used in the Vendetta are SERVO (or DC offset control) only, and work exclusively below 1HZ The SCP-2T is both Direct Coupled and Complementary J's"

 

He added that your RIAA may have a tendency for a more "brighter" sonic presentation  over the Vendetta with your RIAA modification. Great Compliments --- I'd luv to hear it sometime!

 

Congrats from me

 

Willco

 

[djb]

OK wilco

but exactly who is John Curl?

[Willco]

OK wilco

but exactly who is John Curl?

 

 

Hmmm- Well I presume you are not looking to lop the head of a Poppy so I'll go along with that request-- This is'll bring the Naysayers out of the woodwork --mark my words

 

Willco

 

http://www.stereophile.com/phonopreamps/640/

 

http://avmax.in/2013/07/02/designer-profile-john-curl/

 

http://www.zoominfo.com/p/John-Curl/30903442

[andyr]

OK wilco

but exactly who is John Curl?

 

C'mon, Tumby - John Curl's da man!

 

Andy

[andyr]

 

Morning Andy, 

 

I asked John Curl for his comments

 

A --On where his Opamp was situated  and its purpose  plus for his views on your Phono.

 

Well Boyo take a Bow!--his exact words were  " The phono preamp described is a very good one"--Kudos from the Legend himself--Woooo!

 

B; His explanation re the Opamp-- "However, the OP's used in the Vendetta are SERVO (or DC offset control) only, and work exclusively below 1HZ The SCP-2T is both Direct Coupled and Complementary J's"

 

He added that your RIAA may have a tendency for a more "brighter" sonic presentation  over the Vendetta with your RIAA modification. Great Compliments --- I'd luv to hear it sometime!

 

Congrats from me

 

Willco

 

 

 

Haha well, Willco, who would've believed you could have gotten a direct comment from the man himself!

 

That is a very interesting feature (using the opamp for DC offset control).  I would presume the SCP-2T has no output coupling cap, as a result?

 

And yes, Allen Wright's 50KHz RIAA mod would tend to make the Muse sound brighter than circuits without it.  Certainly, some mfrs have valid arguments why they choose not to implement it ... but I believe in Allen's theory and think his cutter-head-roll-off correction is a good thing.

 

Thanks,

 

Andy

Edited August 19, 2013 by andyr

[Willco]

Hi Again Andy,--That's OK Djb has spent the last 25 years in a Monastary in Mongolia learning throat syncing

 

Nah I'm a good friend of JC's -he and I talk often--he usually stays away from commenting on products but yours piqued his interest-- he doesn't suffer idle banter but tends to say it as it is--much to the chagrin of his detractors.

 

Yes I have full endorsement  in the late Allen Wrights projects-- we are both from Wgton NZ--I knew him as perfect gentleman and a fine Audio Designer you can go his way with confidence.

 

His Wright AM Tuner is still regarded as the AM benchmark.

 

Keep posting your developments-- unless they are Classified!  -JC I'm sure would like to hear a report of your product in full fruition.

 

Good luck

 

Willco

[djb]

Wilco was not trolling

I will read with interest

old monk can learn new tricks

Edit read the articles now much better educated on the nature of Curl.

Edited August 19, 2013 by djb

[A J]

Wellingtonians hmm - shakey lot

[Willco]

Wellingtonians hmm - shakey lot

Worse--Hutt Valley actually !

 

Willco

[Warren M.]

Haha well, Willco, who would've believed you could have gotten a direct comment from the man himself!

 

That is a very interesting feature (using the opamp for DC offset control).  I would presume the SCP-2T has no output coupling cap, as a result?

 

And yes, Allen Wright's 50KHz RIAA mod would tend to make the Muse sound brighter than circuits without it.  Certainly, some mfrs have valid arguments why they choose not to implement it ... but I believe in Allen's theory and think his cutter-head-roll-off correction is a good thing.

 

Thanks,

 

Andy

 

The enhanced RIAA equalisation is not Allen Wright's invention, though he championed it for a long time when it was largely ignored by a lot of other amplifier builders.  Today many top-end phono preamp builders use a modified RIAA curve to compensate for the Neumann cutting lathe's frequency response curve which extends well above 20KHz.

 

Cheers

Warren

[lovetube]

The enhanced RIAA equalisation is not Allen Wright's invention, though he championed it for a long time when it was largely ignored by a lot of other amplifier builders.  Today many top-end phono preamp builders use a modified RIAA curve to compensate for the Neumann cutting lathe's frequency response curve which extends well above 20KHz.

 

Cheers

Warren

Hi Warren.

are you talking about the Neumann time constant ? lot of poeple apply this to their phono stage lately.

cheers

Duc

[andyr]

The enhanced RIAA equalisation is not Allen Wright's invention, though he championed it for a long time when it was largely ignored by a lot of other amplifier builders.  Today many top-end phono preamp builders use a modified RIAA curve to compensate for the Neumann cutting lathe's frequency response curve which extends well above 20KHz.

 

Cheers

Warren

 

Mmmm, Warren, you seem to have a different understanding of what Allen "championed"?   The gist of what he said, AFAIAC, is:

• lathe operators deliberately introduce a roll-off at 50KHz (which is not part of the classic "RIAA" compensation curve  :eek: ), in order to prevent their cutting heads burning out.
• hence, they are not actually implementing the RIAA compensation correctly!
• thus, recordings will sound rolled-off ... compared to how they should sound, with "classic theory" RIAA equalisation.
• hence, there needs to be a 50Khz boost in the RIAA equalisation, to compensate for the roll-off introduced by the lathe operators.

Allen's introduction of an extra resistor in the RIAA network, provides this boost.

 

 

Regards,

 

Andy