Driving a 600R LCR RIAA stage

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shane
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#31 Re: Driving a 600R LCR RIAA stage

Post by shane »

No problem at all Mark, it's really good of you to take the trouble!
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#32 Re: Driving a 600R LCR RIAA stage

Post by Keith Haywood »

Hi All

I have been following the phono stage debates and discussions, for some time!

Having seen Dave The Bass post regarding interstage trannies, decided I ought to join up. Especially as I was thinking about building the S.Bench LR phono. Not seen much on this in recent times, can anyone comment? I particularly like the: SUT, D3a's as triodes, trannies, LR No Caps, Schottky/diode cathode bias, Slagle version (last version), I would think with this bunch you must get excellent results from LP's etc. I wondered if Paul (Barker) ever built the slagle version, and if he did what the outcome was? I realise there are no PCB's now, but I am not interested in building that way. I have not aspired to an SUT as yet, but believe it is the best (only?) way to get the maximum most satisfying results for records.

I also note that Mark has abandoned transconductance front end approach, NoSUT! But new version looks interesting (components especially so), have you decided go with the Slagle 1.5k LCR Mark?

Any/all comments would be most welcome

Keith
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#33 Re: Driving a 600R LCR RIAA stage

Post by IslandPink »

Shane - I put the circuit up on Thomas's thread, seemed more relevant to that discussion.

Hi Keith - good questions there . I would definitely encourage you to try the Bench LR , it sounded excellent at ETF 2005 ( was it ? ) . I presume Dave can still make the chokes for it. Did the second version use D3a to drive the LR bit ?
The first valve was a bit mad and probably hard to find matches.

The SUT business is a tough call. For the upper mids and treble, I couldn't so far find an approach that suited me better than a very good SUT ( eg. Tribute ) . On the other hand, in the bass, and for pace/timing on rock etc., you are always at a disadvantage with an SUT , especially so if you use high-impedance carts like the Denon 103 or 103R . Unfortunately these are the best affordable carts for midrange tone ! However, if you've used a Denon 103 with a head amp or jFet input and got rid of the time constant associated with the SUT inductance then the low bass is a revelation. Personally I still found the jFet, when used in the jFet/triode cascode, made the upper mids slightly artificial.
Any SUT will however always remove a little bit of tone and low-level information. The ultimate approach to my mind is to feed direct into a valve phono . I have never been sure if this was worth trying as many have failed , but recently I was lucky to try this exercise into Nick's 'Music First' phono with pentode front-end , and it worked ( at least for my purposes - You could only hear the hiss if you put your ear right close to the speaker cones ) . You could tell a slight veil had been removed and the reverb/space feeling had improved. I have also heard that 6C45Pi's are a good candidate for a low-noise triode input stage .

I have got the Slagle 1.5k chokes ready Keith . Maybe later this year I can get onto this job ? ha ha ha ha :confused3: I have slightly changed my plans about the circuit detail, after what Nick has done with the M.F. - but I'll let him comment as I don't want to go too far in talking about that .

Which cart are you likely to be using ?
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#34 Re: Driving a 600R LCR RIAA stage

Post by Paul Barker »

No I didn't build an LR phono stage.
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#35 Re: Driving a 600R LCR RIAA stage

Post by Keith Haywood »

Hi Mark

Thanks for comments, I was under the impression all versions of the S.Bench LR phono made it to that ETF 05? I know he was due to finish the Slagle version in time, and published all the revised components with the Slagle kit.

I currently use a Benz Micro Glider SL (in an up to date Gyrodec, with Funk FXR arm) it is getting a little tired now, but will probably go for the Wood SL next time, which is basically the same as far as the SUT is concerned, ie 560uV o/p and 12 ohms. I was hoping Dave Slagle is able to offer the trannies and inductors for the S.Benc LR phono! I would also get him to make best quality SUT's specifically to suit the whole phono system.

BTW, I currently use a ANT Kora MC Ltd Edition phono stage, this is a cherry picked jfet design. I built my own dual/LiPo 24V power supply which makes a big difference, if only it was possible with LiPo's for valve stages!

Incidently I did contact Christian Rintelen, who as you probably know built all three versions! He would still recommend the S.Bench LR, but has not used his for some years. He favoured the Sowter version over the Slagle, but used a high output Benz Micro LP!

The Slagle version used D3a in both stages with commoned diodes for cathode bias. Positive current feedback resistor on 2nd stage cathode to heater (12.6Vdc) supply. I think the Sowter version is basically the same, with revised components to achieve flat RIAA equalisation/stability. I have no experience with the D3a, but get the impression it will take some beating.

I did note that you was impressed with Nicks recent efforts. I assume this is cascode or similar no SUT?

Paul
I was under the impression, that back in 2005 you had ordered the trannies/inductors from Dave Slagle for the S.Bench LR phono (another P.Barker)?

Keith
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#36 Re: Driving a 600R LCR RIAA stage

Post by Nick »

I did note that you was impressed with Nicks recent efforts. I assume this is cascode or similar no SUT?
No, its designed as a MM stage, no jfet or cascode, its got enough gain (52dB) and is quiet enough to use directly with a 103r level MC. It depends on how picky you are about silence when not playing a record.

http://www.longdogaudio.com/project/mus ... amplifier/
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#37 Re: Phono Stage

Post by Keith Haywood »

Hi Nick

I had a quick look on the Longdog site, I presume the circuit diagram is there somewhere? I noted it is RC RIAA EQ, can you sum up the audio quality, and your experience in use so far? Was it your goal to avoid an SUT?

I read the Hifi World article (and web site info) on the £10k Ref Music First phono stage, with air cored inductors for the LCR RIAA EQ and buffer stage. I remember thinking, if I had £10k to build a phono stage, I'm sure I could do a better job O/A?

As a general observation/recommendation I think isolated valve bases on phono stages are worthwhile. Pearl ISO bases are available, but I was going to do my own with custom oversize Teflon valve bases (Luciano).

Small mistake. C.Rintelen used a Benz Micro Ebony High Output cartridge!

Has anyone built a Rod Coleman Shunt Cascode phono Stage, with PC86 or E88CC?

Keith
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#38 Re: Driving a 600R LCR RIAA stage

Post by Nick »

I read the Hifi World article (and web site info) on the £10k Ref Music First phono stage, with air cored inductors for the LCR RIAA EQ and buffer stage
The Longdog Phono stage that Mark heard is the one I make and sell via Music first. You may be thinking of the earlier jfet cascode one thats there as well. No, the circuit is not there.
I remember thinking, if I had £10k to build a phono stage, I'm sure I could do a better job O/A?
I look forward to hearing the result :-). Though remember to add on the cost of CE and EMC testing and marketing and dealer costs. Oh, and hopefully making a profit as well.
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#39 Re: Driving a 600R LCR RIAA stage

Post by izzy wizzy »

Nick wrote:I look forward to hearing the result :-). Though remember to add on the cost of CE and EMC testing and marketing and dealer costs. Oh, and hopefully making a profit as well.
A very diplomatic reply there Nick :wink:

These phono stages are a piece of piss really.
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#40 Re: Driving a 600R LCR RIAA stage

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:lol: :lol: "You guys......you guys....!"
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#41 Re: Phono Stage -General

Post by Keith Haywood »

Nick said
" I look forward to hearing the result :-). Though remember to add on the cost of CE and EMC testing and marketing and dealer costs. Oh, and hopefully making a profit as well.

No offence intended, just my thoughts after reading review etc. As I remember, it was the power supply I felt was somewhat lacking, considering the asking price. I realise a profit margin and other considerations must be considered when is business, and this is where we are able to save some cash. If you, and others, 'professionals' are willing to offer advice to enthusiastic 'DIYers', we must be grateful.

Mark
Did you get to, the ETF 2013 (Berlin)? There was a LR phono shoot out that year, I would be interested in any comments.

Keith
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#42 Re: Driving a 600R LCR RIAA stage

Post by Nick »

As I remember, it was the power supply I felt was somewhat lacking
Reviews often dont tell the whole story, the supply part that is in the smaller of the two boxes is just transformer, rectifiers and first stage regulators for B+ and heaters. The actual phono box is where the four other shunt regulators for the B+, and four series regs for the heaters live.
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#43 Re: Phono Stage -General

Post by IslandPink »

Keith Haywood wrote: Mark
Did you get to, the ETF 2013 (Berlin)? There was a LR phono shoot out that year, I would be interested in any comments.
Keith

No, sorry Keith - just 2004 and 2005.
Would have been interesting for sure. I will say though, that making fine judgements between different circuits in a big organised event like that can be misleading. I guess if you can look at the actual builds in detail too, it helps. What I mean is that parts choice ( caps/resistors ) , wiring and earthing policy could easily make as much or more difference to the sound as the differences between the circuits or the choice of LR chokes. System context will also have an effect too, as the 'house' systems at ETF have been somewhat idiosyncratic rather than 'neutral' !
Were these LR units all based on the S.Bench circuit ? - or have there been any new ideas since ?
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#44 Re: Phono Stage -General

Post by izzy wizzy »

[quote="IslandPink"What I mean is that parts choice ( caps/resistors ) , wiring and earthing policy could easily make as much or more difference to the sound as the differences between the circuits or the choice of LR chokes. System context will also have an effect too, as the 'house' systems at ETF have been somewhat idiosyncratic rather than 'neutral'[/quote]

Once I changed how I laid out the circuit on one channel using exactly the same parts. There was a worthwhile difference and I was a bit surprised by the magnitude of it. Many phonos are built on PCBs to ensure a repetitive, good layout as the variation in hard wired layouts could vary enough to cause problems.

cheers,

Stephen
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#45 Re: Driving a 600R LCR RIAA stage

Post by Keith Haywood »

"Island Pink Wrote: Were these LR units all based on the S.Bench circuit ? - or have there been any new ideas since ?

Thanks Mark for reply, fair enough.

No these were 5 or 6 varied circuits, valve and SS. Pete Millet (Texas) done a PCB Op amp based LR phono, which although said to be VERY good fell by the third stage. I was seriously considering this some time back, and PCB's were available, but decided against Op Amps/PCB's. A German Non SUT SS Jfet/Op amp circuit won! I think the info is still out there on ETF13 or Pete Millet site?

Have started collecting components for a Phono stage, must contact Dave Slagle about availability of kit for S.Bench LR phono!

Keith
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