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Old 13th November 2007, 12:08 AM   #1
amc184 is online now amc184  New Zealand
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Default Arcam Alpha Plus

Hi guys,
Just got my fist decent CDP, an Arcam Alpha Plus. I bought this player with the intention of immediately modifying it, so I have already cracked it open to take a look. This CDP seems to have been made to be easy to mod, the whole DAC section is separate from the digital filter, etc. and lifts straight out on it's own board.

I've already had a look through the CD63 modification thread (parts of it anyway), and had some mods in mind already. However, most things I would of change are already done factory. There is no muting transistors (it has a mute relay), the coupling caps are Blackgate F, the TDA1541A seems to be well decoupled, and the power supply looks good (separate from digital supply, LM317/337 regulated, even has a separate transformer from the digital section). The only thing I can think of is to upgrade the I/V stage opamps. It currently uses two OP27's and two NE5534's (yes, both single opamps, excellent). I am thinking of removing these, installing sockets, and trying some of the new LME49710's that I have already.

Do any of you guys have other suggestions, on the type of opamp, or on other possible upgrades.

Another thing: this CDP is 15 years old, should I be looking at replacing the electrolytic caps (barring the BGs, which according to some should have only just worn in)?

I will post a photo of the DAC board soon.
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Old 13th November 2007, 03:46 AM   #2
amc184 is online now amc184  New Zealand
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Here is a picture of the DAC board. It seems to be down stream of a SAA7020 filter, which is located on the main board with the crystal, servos etc.
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File Type: jpg arcam alpha plus dac board.jpg (91.2 KB, 623 views)
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Old 13th November 2007, 12:03 PM   #3
zanash is offline zanash  United Kingdom
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you should be able to do better than the factory fit decoupling caps ....try pio's [paper in oil]

Also check out what diodes are fitted .....

The age of the unit normally means a psu cap change is a good idea I used pannasonic fc

you can't damp the case too much either
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Old 14th November 2007, 01:58 PM   #4
MJW is offline MJW  United Kingdom
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Default Arcam

Lots you can do to this player. It is a good machine actually the ouput stage is pretty much the same as some big name/budget players of the past.
As Zanash said, all the standard lytic caps could be replaced but don't go mad. It's a nigh on 15-20 yr old machine.
The Pana's are good for PS
I'd change the diodes for shotkey or HexFRED's what ever is cheap
Oscons for the Digital but ensure there's a little track length to the load they like a bit of inductance or elna cerafine or rubycon FZ or FL
By-pass the lytics with wima mkp or similar (read cheaper) not the BG tho unless its thier own BG Nx Hi Q which are Fab actually (well I like them) remember I'm on decouple here not coupling, by- passing on couplig caps I think is for the turds or do I mean nurds, forget it, its rubbish. All the little Evox Rifa's are nice anyway leave them.
A cheap master clock 11.289mhz I think, make seperate PSupply for it with little tranny 2.5va. Dont't pay much for it!!! Not aNAME one in other words.
The OP27 are actually ok but you could try OPA627BP dIL OR the version 627AU SOIC 8066? 4562lm? cant' remember the precise designation, sorry. De-couple right on the op-amps, real tight. 0.1uf Tant on BG HIQ or mkp.
Use Buson Audio's (in Oz actually) discrete op-amp for the buffer, those are much better than all of the usual suspects
Blackgate N for the output or you could try Zanash's pio or Elna SilmicII in the analogue-genrally
Trace the circuit path back from the RCA and pick out the key signal path resistors-lots of choices, personal preferance, mine here is Vishay, Bennic. Just don't spend too much.
Damping is V important as is shielding. you could get great results cheaply by using your noddle and think small heat sinks for ram chips in PC's. that aluminium tr ay you just ate your curry from, some rubbery goop from the hardware store. Little pieces of plywood stuck to goop makes V effective damping. The reciever servo board radiate a lot of RF-well box em in, don't short anything and remember don't leave big thin slots. the RF will go through it na bother, little holes-fine, big slots no.
Hard wire your interconnect-you know thwe one you made your self. You can get some nice cable glands. Easy and worth it.
Same with you power cable. Make your own. 5 insulated conductors 1-1.5 mm per pole.bunch them together, end-on they look like a dice showing the number 5. Twist, then secure at both ends. heatshrink (polyolefin please). So centre is earth/gnd and opposite pairs are live and neutral. I use this config for everything. Only difference, with mine the four outer poles are made of double foil, double braid Ethernet 2mm core. The earth picks up the shields' ends at the wall plug and drains down to GND. Shield are not connected at the equipment end (obviously-floating).
Try that. It's good. It's V cheap, and it will upset your friends when they realise they wasted money on boutique PWR cables. This one's 10
You get the impression I hope that your imagination and patience to read and discover is the only limting factor. Don't get carried away with spending tons of cash. IF YOU DO, SPEND IT ON THINGS YOU CAN RECYCLE Opps not shouting into a future project. If decide to keep it (the CD player) look for a doner machine. CDM 4/19 transport I think-its quite good.
Have fun
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Old 14th November 2007, 08:36 PM   #5
amc184 is online now amc184  New Zealand
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Thanks for the replies, especially that very detailed post MJW. I definitely have a starting point now. From your post MJW I understand that the OP27s are the for the I/V, the NE5532s are buffers, right?

From this the first mods I am looking at doing are:
- Replacing all the electrolytics. The main reservoir/filter caps, the 1000uF ones, I will replace with basic Nichicon VRs or similar. The smaller ones I will replace with panasonic FCs or FMs, wichever is cheaper.
- Socketing the buffer opamps, and using LME49710 in this position. These are the single version of the LME49720, which seems to be similar or slightly better than the LM4562. I haven't heard much about the LME49710 yet, but all I have heard is good.
- For the output coupling caps, I think I will try it as it is (Blackgate F)for a while, then maybe try a pair of 1uF polycarbonates I already have.

As far as supply decoupling goes, I am more or less satisfied with what it already has (evox MKPs for the opamps, evox MKTs for the TDA1541A), so I will leave this area for the moment.

For damping: I will certainly experiment with this, as it looks like a cheap and easy upgrade. This player is actually not too bad already. I have a cheaper, modern yamaha CDP already, and that thing is made out of paper thin steel, and must vibrate like a drum! However, this arcam has extruded aluminium sides and back, a 2mm plate bottom and front, only the roof is sheetmetal, and it is already foamed where it meets the chassis. So I'll probably just damp that for a start.
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Old 17th January 2008, 11:02 AM   #6
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Hi amc.
Have you done any of the mods ?
Just a note to say that I think the ne5532 is a dual device, and the single is the ne5534. I have used lm4562 in a delta 70 to great effect.
All the best.
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Old 17th January 2008, 06:01 PM   #7
amc184 is online now amc184  New Zealand
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Yes, I have done most of the mods talked about above. What I did was:
- Replaced the NE5334 opamps (NE5332 was a typo) with LME49710 (much the same as an LM4562).
- Replaced all of the power supply electrolytic capacitors with low ESR types.

I have some 1uF polycarbonate capacitors which I am about to use to replace the Blackgate N electrolytics in the ac coupling position. I am mainly replacing these as I am not sure the will be performing well due to their age.

The mods I have done have made a good improvement to the player.
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