Faulty Arcam Alpha 5 (help needed)

Today I collected a totally standard Arcam Alpha 5 CD player which I intended to keep as a spare for my other Alpha 5 which has received a number of modifications (see my thread in DIY section).

The player powers up fine but won't read any discs. The turntable motor spins but it won't recognise the disc and after a little while an ERR message comes up on the display.

Since I have another Alpha 5 I swapped the DAC boards over and the DAC board from the faulty player works perfectly in my other one so I can be sure that the fault is somewhere with the main board or laser/transport assembly.

Any suggestions? I have a copy of the service manual if anyone needs to see it.

Many thanks, Mike

 

Sounds exactly like a faulty transport mechanism.

 

Last night I finished transplanting the laser/transport assembly from the 'faulty' player into my 'known good' player. This eliminating the other variables.

This confirmed my fears and the laser/transport doesn't work when used with the main board and dac board from my good player.

So it looks like the fault is with the laser/transport somewhere.

I suppose I now need a spare player for my spare player......

 

In the end I took the gamble and purchased one of the 'reconditioned' lasers being sold by various China and Hong Kong based ebay sellers.

I just finished fitting it and it works perfectly. I'm one very happy bunny.

For anyone interested the ebay seller I used is zhzy5500

The only problem now is that I have a totally standard Alpha 5 to compare against my highly modified one. I'll soon find out if all that effort was worthwhile or not!! There's no hiding.

 

Excellent - a noble experiment.

 

I look forward to your impressions. Make sure you connect. Both to your pure at the same time and then you can switch between them instantly.

 

I've been doing quite a bit of back to back listening comparisons between my modified Alpha 5 and the stock Creek CD60 which I recently acquired.
Once I've had a decent amount of listening time with the standard Alpha 5 I'll post some listening comparisons.

My plan is to connect all three players simultaneously to my pre-amp. I'll then burn three identical copies of the same album so that I can start all players at the same time and switch between them at will (see remote controls are a good thing). I think I've even got three identical audioquest interconnects too.

I'm hoping to get a friend over for a second opinion and perhaps to enable me to do blind tests.

It should make for an interesting comparison. It might take me a week or so to get some quality listening time in. I'll let you know how it goes.

 

The Creek may have a different output level, even if just slightly so it might not be a fair comparison. Hopefully the two Arcam players will have the same level. You didn't change any resistor value on the output stage did you?

 

I've now had some time to do a bit of A/B/C comparative listening between the three players.

Before I get into the specifics of the listening comparisons here's a summary of the three players:

Arcam Alpha 5. Totally standard and unmodified. TDA1541A DAC chip, SAA7220 P/B digital filter chip (4x oversampling), Philips CDM 9/44 transport mech.

Arcam Alpha 5. Highly modified with NET audio super non-oversampling conversion, upgraded electrolytic capacitors throughout, dedicated clock PSU, Dexa technologies discrete op-amps and numerous other little tweaks (see thread in DIY section for details).

Creek CD60. Totally standard. TDA1541A S1 (single crown) DAC chip, SAA7220 P/B filter chip. Philips CDM 4/14 mech. This player has a higher specification than the A5 with a better power supplies etc.

I have been listening with all three players connected to my pre-amp at the same time. My pre-amp has remote control allowing me to switch between the players at will. I made multiple copies of some of my favourite albums (WAV files) allowing me to have the same tracks playing simultaneously on all three machines.

Subjectively the output level of all three machines is very similar with perhaps the modified A5 sounding slightly louder. I tried to compensate for this by reducing the volume very slightly when switching to this player.

Conveniently the remote controls seem to be universal between all three players.

I haven't been able to do any blind testing yet so this was a 'sighted' comparison.

 

The first things that is obvious is that all three players sound very good indeed to my ears. I'm really starting to become a fan of the TDA1541 DAC chip. There is already been a huge amount written about this chip so I won't bore you by going into it any further. All I'll say is that the TDA1541 does sound different to many modern DAC chips and if you get an opportunity to listen to a well implemented TDA1541 set up I can recommend you give it a try.

These old CD players from the 90's also seem to be very well made in my opinion, particularly the transport mechs which are often much more solidly engineered than the ones you get in modern players.

Anyway back to the listening...

After just a few minutes of A/B/C listening comparisons it becomes clear that two of these players sound very similar with the third having quite a different presentation. What might be surprising at first is that it is the std A5 and the CD60 which sound very similar to each other and not the two A5's.

Whilst at first glance this might seem counter-intuitive it actually makes perfect sense when you think about it. The two A5's might share the same front panel and look similar but really when you get to the guts of the music reproduction the CD60 and std A5 have more in common. Both use the same DAC chip (albeit with the CD60 having a 'graded' version) and both players use the SAA filter chip with 4x digital oversampling and both use conventional IC op amps and electrolytic DC blocking caps etc.

The modified A5 has obviously has quite a different style of presentation to the other two players.

To begin with I want to start by comparing the std A5 to the CD60. As already stated these two payers seem to reproduce music in a very similar style with only subtle differences between the two.

The best way I describe it is that the CD60 sounds like a more polished, more refined version of the A5. The sound-stage seems to have marginally quieter background, there is also slightly more detail and the bass is slightly tighter.

If anything the A5 has a slightly bolder character, a little more up front and punchy perhaps than the CD60 which possibly some listeners might prefer. To me though the CD60 is the more accomplished player. Fine details are more clearly audible on the CD60 and there is a greater depth to the sound-stage with better separation between instruments.
Fundamentally however the A5 and CD60 sound very similar to each other. Think of a CD60 as an Alpha 5 de-luxe and you get the idea.

The fact that you can pick up an Alpha 5 for less than £100 nowadays makes them a real bargain.

 

A two horse race.

For the sake of simplicity I'm going to eliminate the standard A5 from the listening comparisons at this point. I've already established that the standard A5 and CD60 do things in a similar way with the CD60 coming out on top in that particular battle.

There is however a much greater disparity between the modified A5 and the CD60. Again, both sound excellent to my ears but they do have markedly different sonic signatures.

Switching between the CD60 and A5 it becomes apparent that the CD60 sounds the more analytical of the two and the A5 sounds more 'open'.

If I look at my listening notes for the CD60 I find lots comments like these:

Clean sounding, precise, excellent micro details, superbly solid bass texture, greater separation between instruments and harmonies, sharp highs, powerful sounding.

And if I look at the same notes for the A5 I see lots of notes like this:

More relaxing, draws you into the music more, better sense of 'real' and 'live'. Less fatiguing, very analogue, warmer, better flow.

The above may be rather clumsy descriptions but I think they get the message across.

Overall the modified Alpha 5 would be a good CD player for people who do not usually like CD players. It sounds wonderfully analogue and really excels at long listening sessions were it never sounds fatiguing and has a real knack for drawing you into the music and getting your toes tapping.
Compared to the CD60 the A5 has a slightly more 'warts 'n' all' sort of presentation. The CD60 in comparison never sounds anything short of composed and excellently resolved. Indeed the CD60 unquestionably does some things better than the Arcam, it reveals more micro level details and puts more space and separation between instruments and harmonies. Complex percussion comes over particularly well on the CD60 and bass lines often come across with better solidity making the A5 sound a little fluffy in comparison. However the CD60 does sound a bit shut-in and overly polite when coming to it from the Alpha 5.

If I had pick one player out of the three it would have to be the modified Arcam Alpha 5. Simply put it just sounds effortless and pleasant to listen to. It connects you more emotionally with the music in a way which is very satisfying in the long term.

If I was to start again from scratch there would be a very compelling argument for just sticking with a bog standard Alpha 5. For the money it's an astonishingly good player and you'll probably derive more listening pleasure by spending your money elsewhere, preferably on CD's.

The Creek CD60 is the trickiest for me. It's a beautifully well engineered player and was almost certainly a much more expensive player when new. It does some things better than the modified Alpha 5 yet can't quite match the latter for sheer listening pleasure. I hate to say it but I think the only way forward is to spend some money on the CD60 to find out what it is really capable of. I've a sneaking suspicion it might really shine with a bit of careful jitter reduction by re-clocking the SAA7220. Keep an eye on the DIY section for the start of another slippery slope of modifications.

 

I recently acquired a spare DAC board for my Alpha 5 off ebay.

The previous owner had replaced the DAC chip (upgrading to an S1) after failed and had not tested the board since carrying out the repair.

I tested the board today and the output is heavily distorted. Any ideas where to start?

Thanks, Mike

 

The following test voltages are all OK:

5v on Pin 27 and 28 of TDA1541A

+15/-15v on pins 4 and 7 of OP-27 (both channels)

+15/-15v on pins 4 and 7 of NE5534N (both channels)

The TDA1541A seems pretty warm, I think too warm.

 

There should be -15v on the tda1541 around pin 15 too ( check datasheet for pinout!)

ETA: it is pin15:

 

Hi Felix,

-14.8v on pin 15 which according to the service manual is fine.

-5v on pin 26

+5v on pin 27 and 28

 

I'd then check all the solder joints very carefully.

After that - whats the voltage (dc) on the output of the OP27s, pin 6 on each? I've got a cope of of the service manual somewhere, I'll have to have a look at the schematic. IIRC Arcam inject a bit of current to set the offset close to 0v here; if somethings awry and the dac sees too much voltage eone way or another on its outputs (more than +/-25mV on pins 6 and 25 relative to 0v) then gross distortion will result.

 

Pin 6 on the OP27's

L channel 0.77v

R channel 0.67v

Bad news?

 

What voltage do you see on pin 2 of the OP27 to 0v at the dac (should be 0.00v), and what voltage do you see across R2 for example..?

I've got one of these players somewhere, I'm going to dig it out this weekend to cross-check....

 

The voltage across R2 is 6.96v.

If I measure from pin 2 of the OP27s to pin 5 (analogue ground) of the DAC I get 0.00v

I have a working DAC board here as well if you need me to take any comparative readings.

Thanks for the help.

 

OK, that's good. The current through R2 and the current through R4 come to -2.0mA flowing into the dac's output pin as they should at digital zero (no signal idle). That's a very good sign for the dac, essentially it means all the internal bit current sources are present and working correctly, as is the I/V stage at DC.

Could be time to start looking hard at the output stage rather than the dac itself...