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Old 27th August 2010, 02:21 PM   #21
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Originally Posted by SimontY View Post
I chucked out the old buzzing audio section transformer, and installed a much larger potted Avel Lindberg toroid in its place. Luckily it was an easy straight swap and this alone made quite a large difference to sound quality. It gives that cleaner "toroidey" sort of sound (you could say slightly anaemic by comparison), but with welcome increased dynamic snap.
Simon Hi

This is great.
I have an Alpha which I always preferred to the 5.
I too have the buzzing tx hence me fiddling on with the 5 instead - got fed up trying new tie straps and shims to shut it up.
The tx you replaced it with, is it a +24 0 -24v job ?
I have the service manual and it implies 24 volts.
What VA rating did you use please ?
looks an easy swap.

Thanks for the link to this thread !

Andrew
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Old 27th August 2010, 06:44 PM   #22
SimontY is offline SimontY  United Kingdom
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I don't know what VA rating the transformer is but from the size I'd say maybe 40 or 50. I think I have one spare if would like to part with say 9 (posted). It's a high quality potted Avel Lindberg job. I can look up specs later if you'd like to find one elsewhere. The swap is really easy and REALLY worthwhile. The sound is better and the buzzing makes the player worthless.
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Old 27th August 2010, 09:43 PM   #23
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Simon Hi

That's very kind of you and yes please, I'll have it.

Did you also complete the NOS conversion and was it worth it ?

It's a long story but I first had the Alhpa 5 plus that had already been modded to hell, SM bypass cap's on all the upgraded electrolytics, also on the TDA1541a caps and tant's and also across the 4 pin tx inlet ( that sit's on the legs from the monoboard ) NONOS using bits of straight wire across the now removed SAA7220 connecting the usual 1-18, 2-16 and 3-15 plus a link between pins 9 and 11 ....that was it. No evidence of any
other links or wire, believe me I've checked the lot.
It worked beautifully, no clicks with mutes out or de emphasis tranny's out.
I fitted 627's to I/V and Audio GD Sun's as ouput stage and finally big polyprops.
A drop in gain was noticeable compared to my other CD player but it was sounding very good.
Fitted a clock ( another step up ) and then after a few months it unexpectedly burned out some resistors and I lost some tracks around the reg's of the DAC board.
Binned, well not quite but was I unhappy ?

Then I bought the straight old Alhpa and was totally blown away by it.
How the hell could an 80's machine sound like this ?
Love affair has now started....then the buzz - how many times I tried to
shut it up I can't tell you.
Picked up an Alhpa 5 two weeks ago and pulled the DAC board to fit to my old 5 plus - it worked but sounded like sh..
A few cheap tweaks and it's smoothing out a bit but absolutely no where near as good as the stock Alpha - how bizarre is that ?.

I'm more than keen to give it some TLC and some upgrades - the transport seems better, the case is much stronger and the DAC board looks higher quality.
I'm surprised there has not been more about this machine as a modding project.
What you've done proves that it's not just me that thinks it a worthy bit of kit.
It's hard to imagine how your machine sounds with all that work you've done
there but for me in standard form it was about bass control and sound stage ..which was a real shock.
I imagine yours probably sounds like a top Naim machine maybe ?
Hope that is not an insult ?
Not meant - the good ones are extremely good, you'll know that anyway.

If your not asleep yet I'll be poring over your upgrade thread quite a lot in the hope I can understand it and finally - I'm very happy with your offer

Thanks
Andrew
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Old 29th August 2010, 10:49 PM   #24
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Simon Hi
I'd like to buy the traffo please ?
Is this one of those.........' Bump ' .....moments ?
Thanks
Andrew
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Old 29th August 2010, 11:01 PM   #25
SimontY is offline SimontY  United Kingdom
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Hi Andrew,

Apologies for the slow response, I've been out and about a lot this weekend.

I never did do a NOS conversion because people I trust advised me it was a waste of time compared to upgrading the SAA7220's supply and re-clocking all the chips, which is probably the only true high end solution with these players. The NOS trick sounds like something to do if the budget or skills and parts available are a bit restricted but if you're going all-out to make a great-sounding machine it's not the way forward.

With respect to the Arcam Alpha 5, well I've noticed it's a popular machine with a fairly naff looking front like the others in the range... and of course used the famous and desirable chipset. I always wondered how different it was inside from the Alpha and how far apart the players came chronologically and price-wise. Any light you can shed on this would be quite interesting to me.

OPA627 is a fine op-amp in my opinion, but it's still a long way off the discrete solutions. Audio-Gd stuff I've seen a bit of and it offers superb value for money. Their op-amp modules appear to be clones or at least similar to the Australian company Burson's stuff.

It's a gutting thing to have a player die on you like that, I know the feeling too well
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Old 29th August 2010, 11:10 PM   #26
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I agree with your sentiments towards the Alpha. I also wondered why it sounded so good, but the nice layout of the audio board and that being fed by a dedicated transformer shed some light on it. Then there's the use of the SAA7220P/B filter chip and the A version of the DAC. The transport is also quite highly thought of, so all in all it's not so surpising it sounds well. The op-amps may not be the best anymore but they thought to use different singles for different jobs rather than just a couple of duals. The filter caps in the output stage look to be of decent quality too. It all adds up!

Like you I'm surprised there is little interest in mods for this superb machine. Mine does sound quite good but I'd rather try not to overstate it. I've only heard a top-end Naim once and it's hard to know exactly which parts of the system were bringing what to the party so I don't want to comment. I will say, though, that my standards are pretty high and this two-box monster does make good music. The bass output is superb, the dynamics are considerable and the correctness (timbre) of vocals and other important instruments is very pleasing.

The treble output is nice but probably not first-rate. Likewise the imaging and maybe some other fine points like the overall fluidity/smoothness of the thing. I've been told that some DEM reclocking will lift things in those departments so it's not over yet. I also want to upgrade my main clock as I know there's more to be had in that department.

Needless to say it's capable of making hairs on the neck stand to attention and shaking the room with deep accurate bass with absolutely no harshness - on a good CD.

I will e-mail you about the transformer.

Simon
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Old 29th August 2010, 11:16 PM   #27
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I've found a tx. The outputs are 17.5V @ 1A - 0... x2. It also has a separate screen pin and is potted. It's a nice looking thing. I think when rectified in our house (240V or so!) it puts out about 25VDC - perfect for this job. Anyway, will e-mail about that.
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Old 30th August 2010, 10:50 AM   #28
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Have you filled in all the webbing holes of the CDM 4 base with blu-tak or similar caulking ?

I noticed quite an improvement in doing so in my Alpha Plus great for so little out lay .
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Old 30th August 2010, 10:58 AM   #29
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I've not done that! I did, however, fill in the holes in the CDM's clamp flap with hot-melt glue. I'll check out those other holes the next time I open her up. Cool tip, thanks for that.
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Old 30th August 2010, 11:00 AM   #30
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Originally Posted by SimontY View Post
I've not done that! I did, however, fill in the holes in the CDM's clamp flap with hot-melt glue. I'll check out those other holes the next time I open her up. Cool tip, thanks for that.
Pleasure
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