Arcam Delta 170 + Blackbox

[firestorm]

I have procured a 170 transport and black box dac. It works fine mechanically and sounds ok.

From what I have found on this forum and others is that the dac employs a custom clock recovery circuit.

Can any body tell me how effective this is ?

Is it worth perservering with or is it better to get hold of an Arcam Delta 70.2 instead ? Which I guess will mean it shouldn't have to go through spdif ?

I plan to change the clock and improve the psu. There are 7805 and 7815 regs on board, which I'll replace by two stage LM317 regs. I can't justify putting in superregs in there just yet. There are also 16 year old lytics made by rubycon which can be easily replaced by sanyo oscons, panasonic fc, stargets etc. Then I'll be looking at the clock with independent psu.

I have already changed the clock on my Arcam Alpha and have had very pleasing results from that. I'm hoping that the Delta will be a step or two better once fettled.

Thanks

[firestorm]

any one any comments ?

[tubenut]

The fancy clock recovery with the additional toslink cable is only done on later models I think. Black box 50 and 500.
If you have Mk 1 versions of both units the mods mentioned will make a large difference. Do not forget some soft recovery diodes.
Be careful, I think the 70.2 could be bitstream although I may be confusing it with the 270, bitstream units will give a very different sound to the black box. In fact I preferrd BB2 over BB3 by far for this reason...

Guillaume

[firestorm]

Tubenut, thanks for that. Arcam emailed me their workshop manuals, I'l summarise the info I have on the DAC used :

Alpha TDA1541A
Alpha+ TDA1541A
Alpha 5 TDA1541A
Alpha 6,7 hybrid / bitstream
Alpha 8,9 dCS
FMJ23, 23T dCS

Delta 70 TDA1541A
Delta 70.2 TDA1541A
Delta 70.3 hybrid / bitstream

Delta 170
Delta 170.2
Delta Blackbox TDA1541A
Delta Blackbox 2 TDA1541A
Delta Blackbox 3 hybrid / bitstream
Delta BB 50 hybrid / bitstream
Delta BB 500 hybrid / bitstream

My main consideration is whether the Delta 70.2 single box cdp would be a better foundation for clock and psu upgrades rather than the transport and DAC Delta 170 + Delta Blackbox (original) as the transport to DAC connection is much shorter, much more direct and doesn't use spdif, so should one less jitter component.

You're right about the BB 50 and 500 having separate clock sync line, I was sure the earlier BB had a non standard clock recovery scheme or non standard chip doing it.

Yep soft recovery diodes all round. There seems to be a lot of circuitry in the transport, otherwise I would have considered putting the contents from the DAC to the transport with the psu bits moved to the newly vacated DAC box.

Errors and omissions are all my own ;-)

[jean-paul]

Originally posted by firestorm


My main consideration is whether the Delta 70.2 single box cdp would be a better foundation for clock and psu upgrades rather than the transport and DAC Delta 170 + Delta Blackbox (original) as the transport to DAC connection is much shorter, much more direct and doesn't use spdif, so should one less jitter component.

Well thought, go for the 70.2. Or fit a DIY multibit DAC section in your 170, high DIY content !

BTW, did Arcam send you these manuals as well ? :

Delta Blackbox TDA1541A
Delta Blackbox 2 TDA1541A
Delta Blackbox 3 hybrid / bitstream
Delta BB 50 hybrid / bitstream
Delta BB 500 hybrid / bitstream

If possible I would like to have a copy of those.

[tubenut]

It is all standard Philips fare, you could probably link it all via I2S quite easily anyway or go completely separate.

My main fear with your propsed project is longevity, those lasers are getting old and the DAC could be used with other drives in the future.....

I do probably agree with JP, getting SPDIF right is hard and many of the advantages of separate DAC and transport probably had more to do with PSU separation and more dedication to getting things right on the DAC side then anything else.


Guillaume

PS: JP off topic, do you have an easily mailed set up guide/manual for CDM4 laser based units like Philips 624/850 etc.
A friend of mine in Nigeria is fitting a new laser to his CD850 and would like a service manual.
Any help is welcome.

[jean-paul]

You've got mail.

[firestorm]

Guillaume
the transport is old but if its good I'll hang on to it till it falls apart, I can get a spare laser assembly in the UK without too much effort.

Is it a practical proposition to use I2S for the CD-DAC link ? I wonder if it'll work properly without a driver/buffer ? I remembered reading somewhere that the commercial implementations of I2S for DACs was fundamentally flawed, can't remember where or who said it though.

I would like to stick with my 170 + BB as it means I won't have to go through the hassle of selling it to allow me to buy another gadget .....

I had considered putting the contents from the DAC to the transport with the psu bits moved to the newly vacated DAC box, but there isn't much room. I'll post some photos later.

DIY DAC ? Too much complexity for me to get right, I've studied it for a little while, but getting the decoupling, groundplanes, earthing right is what differentiates a working implementation between a great sounding one. It is beyond my knowledge and budget. I have dabbled in RF and have experienced oscillators that didn't and amplifiers that did ! If I was to do it, I'll have to base it on something that has been proven to work, a well designed multilayer board perhaps with the option to screen certain sensitive components.

So in summary, the next step for me would be to investigate the praticalities for bypassing spdif and toslink by using I2S. I'll search the board before asking more questions on this.

JP ------------
PM me with your email address I'll send the BB pdf manuals to you.

Cheers

[tubenut]

If anyone of you could help me with the service manual for the Delta 70.3 I would be very grateful.

[Fin]

Originally posted by tubenut
If anyone of you could help me with the service manual for the Delta 70.3 I would be very grateful.

Send me a PM with your email address - and you shall have it :-)

Then we can discuss some ideas that are common to the 70.3 and my lekker 70.2....