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  #1  
Old 24th February 2006, 08:21 AM
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Toppsy Toppsy is offline
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Default Valved Phono Stage v Solid state for MC cartridges

Hi All,
my first posting on the new forum!

My WAD PHONOII is playing up and I'm experiencing drifting of the soundstage to one channel. I have isolated the problem to two things. A dodgy valve base and a couple of tracks that have lifted off the PCB as a result of numerous component changes.

I had intended to rebuild but hard wire everything and use tighter tolleranced audio grade components (0.1% Metal oxide resistors and better Capacitors) and wire with 0.5mm dia solid silver. However, having read latest issue of HiFi world on one article Noel Keywood commented that Valved phono stages are not recommended for use with low output MC cartridges because they are too noisy! So I am contemplating building a White Noise phono stage and Cascade Power Supply.

My question is do you guys have any views on this or experience of the White Noise Audio grade phono stage?

At the forthcoming PHONO SHOOTOUT will there be SS and Valve phono stages to compare? If so I may hold off and attend the meet to get a more subjective listen.

Thanks for your time guys.

Toppsy

PS. My front end setup is: Nottingham Analogue Spacedeck (heavy platter) with Mitchell Technoarm 'a' and Rondo Bronze MC.
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Old 24th February 2006, 08:59 AM
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andrew ivimey andrew ivimey is offline
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Default Re: Valved Phono Stage v Solid state for MC cartridges

Hello Toppsy, I think JamesD has promissed a solid state phono stage. I too can bring one; a Michell Iso HR with Lithos PSU hand built by Tom Evans himself as the story goes. I need to put it in a decent cabinet though and the clock is ticking... fast
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Old 24th February 2006, 11:22 AM
James D James D is offline
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Default Re: Valved Phono Stage v Solid state for MC cartridges

Yes, I will have my version of the VSPS (Very Simple Phono Stage) - I use completely different opamps to everyone else, different RIAA schema and a different approach to ground schema and signal layout... And I run it from batteries. Apart from that it is exactly the same as on the web

It's quite good but a good valve stage should bury it... One day I'll finish my valve phono experiements and build a proper unit

James
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Old 24th February 2006, 11:45 AM
buddam buddam is offline
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Default Re: Valved Phono Stage v Solid state for MC cartridges

Colin

I have a WAD PhonoII, with t/xs fed by a Dynavector 20 low o/p. No noise at all.

Adrian
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  #5  
Old 24th February 2006, 12:22 PM
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Default Re: Valved Phono Stage v Solid state for MC cartridges

Adrain,

the noise Noel keywood is talking about is not audible ( as I understand it) but a consequence of the valves and circuit and the need for step up transformers, I think. Talking to a colleague he says this will blank out small detail from the recording so you do not hear all that is in the groove. I get no audible noise from my PhonoII either. I find the sound very good but my mate who has the White Noise Solid State kit swears by it. Noel also conmmented in the article that SS was the ONLY way to go for MC cartridges. Hence my posting.
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Old 24th February 2006, 01:44 PM
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Default Re: Valved Phono Stage v Solid state for MC cartridges

Colin

in which case I'd better make sure I get to the phono shoot-out
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Old 24th February 2006, 01:48 PM
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NealG NealG is offline
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Default Re: Valved Phono Stage v Solid state for MC cartridges

Colin, I think you are reading Noel out of context, to quote:

"...Finally, valve phono stages release a sound from LP that is unmatched for soundstaging. However, valves are too noisy for moving coil cartridges. Either a simple (x10gain) transistor gain stage must be used or a step up transformer..."

This implys a stepup device is need, as we know. It dosen't make sense for anybody to use an low o/p MC cart straight into a valve phono stage without a step up of some sort. Unless the MC cart is a high output variant.

The old KLPP1 did not have step ups and was fine with high output MC's..
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Old 24th February 2006, 01:57 PM
Ianm2 Ianm2 is offline
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Default Re: Valved Phono Stage v. Solid state for MC cartridges

there have been a few efforts at valve amplification to step up the moving coil signal.

essentially, you have a number of options.

1. transformer
2. solid state, either chip or discrete transistors.
3. cascOding your valve stage, this turns a triode into a pentode without the noise apparently, as in wads original pre, which may not make enough gain

or 4. the valve head amp

examples are conrad johnson 6, used nuvistas,

croft made one, not sure of the valve, ecc82 variant possibly,

and 2 other companies both 6922 valves, can't recall who precisely, also audio innovations used an ecc83 in the s200 preamp as a pre moving magnet stage to boost the moving coil signal.

it has been done, whether its any good? I do hope to try one day.Noel knows more than I, but I think it is possible if you do it well.

best route I have found so far is transformers, I had a very well regarded i.c. step up that was fine, but at 10x the cost of my transformers, and not as good, I dind't keep it, there is also a unit on ebay that uses discrete transistors for a good price that I may try, but I don't have huge expectations.

Actually, I have just realised, my basie amp is ripe for converting into a valve phono head amplifier, so if I don't like the latest incarnation, there is room for an active preamp and also a head amp, I had no success with an riaa stage as it was too messy hardiwring all those caps to valve sockets, but the head amp is a poss., will report.

Last edited by Ianm2; 24th February 2006 at 02:21 PM.
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  #9  
Old 24th February 2006, 08:47 PM
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Default Re: Valved Phono Stage v Solid state for MC cartridges

Hi Colin,

Good to hear from you. I thought you were lost

I think Neal is right on his interpretation of Noels column. By example, I'm using an early Ortofon MC30 nos. Output is specified as >0.08mV and infact mine is individually factory tested at channel L, 0.096mV and R, 0.093mV. Consequently my Lundahl step-ups are set at ratio 1:20.

Certainly with Phono II there is phono roar, but it's no more than I had with a higher output MC into a sand phono.

I'm attending Phono-shoot out in the hope of finding an ultimate phono option although recognise that could change the next day James is bringing his Tricord Dino (Hi-Fi Answers 2004 award......not that it means alot). I think you should come as well, even if it's just for the get together, the beer and of course, ripping the mickey out of Paul Barker

Best wishes,

Greg
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Old 25th February 2006, 02:40 PM
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Default Re: Valved Phono Stage v Solid state for MC cartridges

Hi Greg,

You have sold me the ticket. I will now definitely come along to the shootout. I'll keep up with this thread. I might even be tempted to by the White Noise phono stage kit and buuild it before the meet. I should have time if the kits are in stock.

I have been absent from the BB postings lately and this is amiss of me. I have been building some new electrostatics that have been posted me from OZ. These are stacked pairs and promise very good things. Unfortunatley they will not be ready for the phonostage shootout as we are experiencing some quality control issues with asian sourced mylar for the panels. I am awaiting some proper Dupont mylar soon and a new translucent conductive coating to try out before they are publically aired.

So I'll hope to renew friendshipos and meet up with you all in April and have the blag with Paul.

Regards

Toppsy
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