Arcam Alpha mods

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Great power!!

Simon
The mega power supply looks great. I doubt there ever has been a CD that has had more attention to good power than yours. I am willing to bet that it is truely reference grade. I can't imagine any stock CD at any price beating your sound quality.

You have me reading about super regulators. I can imagine that this is the one biggy that I have yet to experience.
Walter
 
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I made a simple change tonight that may not apply to others, but in my rig it was significant.

I ran a ground wire from the center tap of the audio board transformer to the earth ground on the IEC plug.

I had been reading about power supply design for my amp. I kept seeing references to grounding the center tap to create a balanced power source for the +/- dual supply in audio. And it hit me that since I replaced the DAC transformer there was no reference to earth ground on the center tap. It is supposed to drain eddy currents in the transformer before they can create noise that pollutes the supply and the circuit it supplies.

Well in my case it was pretty important. Like so many other changes before it just increased dynamics, sound stage, air around everything. Lots easy natural extension at both ends.

Again, I don't run the full CD, so I don't know if this will somehow have a negative impact on grounding in the alpha that still looks like an alpha.

I am literally rediscovering all the music yet again. What a great machine this ARCAM is.
 
It is a fine machine. I'll think about that mod.

There are others with equal and even better supplies than mine, though they are few and far between. I don't know how my player would now stack up vs a top dollar machine. It would do ok I think but I doubt it would surpass the very finest, but should be close.
 
Thx to all contributors to this experience, i'm actually modding slitly an alpha 5+ , less space to fit any F&T or Bhc on the psu, but with somes nice nichiconzz and panazz Fc all is nice, + mmk for the sound board this arcam gear takes another dimension , next stage i plan to swap 317 337 combozz with linear tech quieter regs + somes heat sink to cooling the dac and Sa bugs!

Bravo to Simon to share your "extrem" experience


P,
 
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The Alpha 5+ looks like a fairly decent player from what I've read. Probably better than the original Alpha I would guess but not had a really detailed look.

I've had another play this evening.. I just can't help myself, I keep wanting more! First, as per Walter's advice, I decided to try connecting the signal ground (from the centre of the DAC PSU transformer) to the safety ground. I did it via a 2.2uF film cap so as to not cause an earth loop. I didn't listen to this mod in isolation as it was just a bonus whilst I had the player on the operating table.
 

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After that little tweak I went to work adding more filtering to my output stage (Pass D1 class A thing) supplies, which are off-board so there's plenty of room to play in. The PSU consisted of a 100VA 25-0 25-0 toroid into a big bridge and 2x 10,000uF F&T caps.

I made this CRLC by adding 2 x 33R 1/2W resistors in series and then an 8mH (or thereabouts) coil. This was followed by some more used Silmics: 1000u/50V, 470u/50V & 47u/63V in parallel per rail. I initially just connected the coil but they only have 1R of DC resistance, which was barely dropping the voltage. I wanted more voltage drop to give the S Power regulators an easier time as they were working with +-37-38V going into them. I tried various resistors till I got the rails down to +-34~35V. I calculated they were only dissipating something like 0.1W each, so quite safe and cool-running.

It's too late to play at test levels but it does sound very smooth, pleasant and with more tonal information than I usually notice. :drool:

I want to upload a couple more pics but it's not working right now! 😡
 

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thx Simon,

just tested op627 to the place of the NE in ouput, pants!

this remove all the analogic raw sound, don't like it!

fitted the Linear Technology 4 regs, and it gets more air between instruments, this regs are really less noisy!
yellojackets have recovered their wings!

next stage? don't know yet, i would stay tuned on Pundits endevouring adavntures!

have a great week!
 
the 5534 gets me full satisfaction, a friend gets me op27 to test, i'll try! but at least i think Arcam was right on this analyse!

don't like analytic tones ..
 
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Those old op-amps sound pretty grey and gritty, not very smooth. I do also appreciate the dynamic rhythmic nature of them.

About ten leagues away from a nice output stage though... like that Pass D1. It does everything right, so very right!
 
Maybe so, to a point. To keep the pedant perfectionists happy I should've said it does all musicality aspects so very well, and concentrates less on the superfluous hi-fi traits that are not an intrinsic part of enjoyment of good music. If an instrument or voice sounds full and lifelike, that is the biggest battle won IMO.
 
SimontY said:
Maybe so, to a point. To keep the pedant perfectionists happy I should've said it does all musicality aspects so very well, and concentrates less on the superfluous hi-fi traits that are not an intrinsic part of enjoyment of good music. If an instrument or voice sounds full and lifelike, that is the biggest battle won IMO.
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+1

thx alot Simon
 
SimontY said:
Maybe so, to a point. To keep the pedant perfectionists happy I should've said it does all musicality aspects so very well, and concentrates less on the superfluous hi-fi traits that are not an intrinsic part of enjoyment of good music. If an instrument or voice sounds full and lifelike, that is the biggest battle won IMO.
Click to expand...

Oooh, steady on there. Was just my opinion, lol.

I just meant that I missed a lot of detail with that output stage, but yes I agree it does have a very relaxing and musical quality to it.

Lee.
 
Not having a go at you chief, just getting my priorities down for all to see.

A tad more detail would alwsys be appreciated, as long as it doesn't come at the expense of those other things. I know you will keep searching, and so you should.
 
No offence taken Simon.

You tried the CCS on the D1 yet? I found it really opened the sound up and allowed a lot more detail through. It was also still far from sterile sounding.

Lee.
 
Not tried it yet and my draw now isn't closing so I need to go in there today ideally. Perhaps I'll do the mod at the same time. Only issue is I'm working on my speakers so knowing what mods did what is not going to be so intuitive.
 
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