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Thread: Stageline phono stage and regulated linear psu

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    Default Stageline phono stage and regulated linear psu

    I make no apologies for my love of Naim phono stages. The phono stage in the downstairs system is made up from two Naim 323 cards in separate boxes with regulated supplies. These cards are usually fitted in Naim preamps such as my 42 etc. These cards give the diyer the opportunity to build a good phono stage for peanuts. There's different cards for MM or MC so they're truly dedicated to the task.
    For my office system I wanted something ready made and nice looking so I bought a Stageline which is basically the same circuit as a pair of 323 cards but built on one board with a common ground. The Stageline would have drawn its power from the preamp or a stand alone psu but my intention at the time was to use batteries. I modified the unit to run from a pair of 12 volt SLA's but after several years of enjoyment I got the itch to investigate regulated linear supplies again so out came the iron.
    Originally I had fitted an on/off switch in the back left hand corner and modded the input socket so the switch could break the supply.



    Ok, so now I've removed the pcb mounted socket and switch and installed a new 5 pin din socket and two Avondale regs. Ideally the regs need to be as close as poss to the phono stage and luckily there's just enough room at the front of the enclosure. The phono stage will now be switched on and off from the psu.



    Here's the linear supply. The regs were originally in here but I moved them to the phono stage and that will allow me to fit the six caps instead of just the original two. This psu will give me two separate 24 volt supplies and I'm going to use one for the left channel and the other for the right.



    Lots of this info is available over on PFM in the diy section. There's also Martin Clarke's Acoustica site that's worth a visit for most things Naim and with lots of info about regulated supplies etc and a host of other stuff.

    More later when the other parts have arrived.
    Si.

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    Very similar to what I'm running Si, so I can vouch for them providing a great VFM phono stage.

    Were you aware that the 323 cards each have an on board simple zener/transistor/resistor regulator that limits voltage to about 21V? If not, best to remove these components and insert a link search Neil Mcbrides Naim mods site for his mod..

    Does the Stageline also have this on board simple reg?

    I'm using MBR 20/200 ultratfast schotky diodes with Les' transformers, Kendeil caps and his TPR 2 regs mounted local to the phono stage boards - it all sounds pretty good to my ears anyhow.

    Good luck and happy fiddling - infectious innit?


    Regards.

    John R.

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    Hi John, yes I'm aware of the on board voltage reg. When running on batteries I leave it as is but when using stand alone regs I remove R11, R26 and Q4 which effectively removes the on board reg. The other components can be left in but a link must be put in across the points that were occupied by the emitter/collector of Q4. Some put a link in where R26 used to be so that C8 is still across the supply but I only do that if there's any instability problems. The same voltage reg is used on the Stageline too so the same rules apply.
    The psu I'm using was donated by Hugh and I'm assuming it's an Avondale unit built by someone else as Hugh bought it to use with some of his gear but wasn't happy with it. I remounted the transformer and pulled out the regs as they really need to be as close as poss to the phono stage. The Cap6 board is a better thing altogether than those rectifier boards and two Kendeils but as I can't get the board in I'll hardwire the six caps. Done this way the phono stage only sees the last cap so you could use two cheap caps up front and a decent one on the end. You'll see what I mean when I get it finished. I hope it works after I've done all this lol. My other phono stage uses a HackerCap board which is the same difference as the Cap6 I suppose. A vestatile board indeed and and every diyer should have half a dozen in the spares box.
    Hugh and I have also invested in Neil's motherboard and 323 cards for this winters project so I'm hoping for another step to audio nirvana maybe

    Si.

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    Yes all great stuff you got going on there Si.


    It certainly looks like one of Les' Avondale power supplies but I think you'd perhaps be better off using an Avondale TPX board rather than the Minicap6 or Cap 6 board as I think they are power amp supplies? Although I'm not au fait with the Hacker cap board you refer to.

    Im also keen to hear what you think of Neil's mother board -- Neil Jadman ?

    I use just one Kendeil 10,000uf capacitor per rail, (probably far bigger than necessary) with the TPR2 regs in the phone stage itself. I'll post some pics of my set up on the W/E.

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    Hi John, you can use the Cap6 and the minicap to power anything you want. The output voltage is decided by the transformer. The C-L-C-L-C of the Cap6 etc gives a much cleaner output to the regulator than just one big smoothing cap. The HackerCap looks just like a Cap6, just a bit shorter. Reminds me I must give Les a call. I need some Cap6 boards for the Napa boards I bought from Malcolm.
    Yes Neil Jadmans MB and 323 cards. I think there'll be some spare boards knocking around soon when some of us decide we've got too much on. Snap a set up if you get the chance. Some built up cards went for fifty notes in the classifieds the other day. Bargain.
    Si.

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    The psu is finished. With the regulators banished to the phono stage there's room to fit the six caps and four inductors. I'm no electronics expert, I just go with the flow and doing it this way gives the best results I've had from a linear psu.

    Here's a pic of the psu with the six caps glued into the sled and the 10mH inductors between each pair of caps. I've also replaced the input caps in the phono stage for something a bit better. Well they sound better to my ears.



    Here's the view from t'other end. You can see how I mounted the transformer with bolts through the front face of the case. Not elegant I'm afraid but the transformer is mechanically silent mounted like this.



    That's it for the moment. Initial listening impressions are very favourable and some of you will get to hear this phono stage for yourselves
    Si.

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    Nice one Si lookin good there, i recon the 4 boltheads look fine, how about stainless steel ones though? that might be classier.

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    They are stainless lol! I must admit I'm not anal about aesthetics but I was thinking of replacing them with black ones or even painting them.
    Si.

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    Strewth they look dull for stainless lol

    If you paint them it wid look like you had covered them up but you'd still see them. How about making a feature of em, four brass knobs on em

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    They look functional Si but I'd personally fit small CSK screws instead and fit a thin black styrene cover plate with double sided tape - easily trimmed this suff is and it'll add a really professional touch I can send you an A5 sheet if you'd like.

    Regards

    John R

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    It looks very functional Si as noted by John, and quite industrial looking, in fact rather than try and hide them, I would be more inclined to simply fix 4 more similar cap heads to the Phono stage casework even if they were fixed to nowt, just to echo the connection between the two items.
    Garrard 301 with SME 3012, Garrard 401 with PU7 both in slate plinths, Puresound P10, Highphonics SUT, Glasshouse TVC Passive Pre, Bel Canto Set 40 (845 power amp), Tannoy GRF Memory`s

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    Quote Originally Posted by Andy831 View Post
    It looks very functional Si as noted by John, and quite industrial looking, in fact rather than try and hide them, I would be more inclined to simply fix 4 more similar cap heads to the Phono stage casework even if they were fixed to nowt, just to echo the connection between the two items.

    Ooh no Andy. If anything I think I'd machine a billet front for the psu similar to that on the Stageline. It'll be a good test putting a curve on it lol.
    Si.

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    Its all down to taste at the end of the day and we are all different
    Garrard 301 with SME 3012, Garrard 401 with PU7 both in slate plinths, Puresound P10, Highphonics SUT, Glasshouse TVC Passive Pre, Bel Canto Set 40 (845 power amp), Tannoy GRF Memory`s

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