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Deltec / DPA

Copperjacket said:
Wow! I didn’t see that coming. Did one amp have a damaged channel? What speakers are you using with them?
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At the point I was interested and had landed a mint pre/power combo, a second power amp popped-up; so I nabbed it - first thought was as a spare; too many people saying - oh that stuff is brilliant - but unfixable.

After a while inner curiosity won: what, how, why - oh, how far can we push such a thing..? (ans: a long way to my taste ... esp once I fixed the one minor weakness in PSRR in the power amps)

I've used the 50S set with all sorts of speakers, DIY and many others; but long term - Impulse H2 horns which I've owned just as long, over 15yrs now, for which they were the finest amps I've tried or heard, valve and many other; and also - and most of the time these last couple of years - serviced Quad 989 ESLs ( I had ELS57s for a few years early on in DPA ownership; loved them.)


I love the lot. 989s currently in rotation, but I'll never let the H2s go. The difference between them are really, really minor ones of presentation, 'you are there' vs 'they are here', in short. Both excel in timing, expression, and musical communication.


Here's my last post in the 'system pics 2020 ' thread if interested:
https://pinkfishmedia.net/forum/threads/system-pics-2020.235557/page-6#post-3869954
- there's a mint late FM4 now in rotation/in place of the FM3.

[ I can & have serviced & rebuilt Deltec 50S and all the related power amps from experience, surface-mount bits and all -by reverse eng. the layout etc. I've even serviced & fixed some for others this way, but since I consider myself an amateur - not a job I seek or offer to undertake, IYSWIM.

On which point - one variant I cannot recommend is the late-90s half-shoebox DPA200 amps: an utter-nightmare to work on, and once done, the cost-cutting/ esp lack of heatsink capacity ensures even once fixed, they'll blow-up again. A shame, really. ]
 
Thank you for that. I had seriously considered the H2’s that were for sale prior to Christmas but unfortunately couldn’t collect.
 
Thank you Martin for your answer. Out of curiosity, I replaced NE5534 with OPA627. I measured with an oscilloscope and nothing bad is happening. I have to listen even longer ... After this rehearsal, I will probably come back to the original. I am just wondering why they did not give any capacitors in the power supply at NE5534, only decoupling 100nF ...
Tomasz
 
I had the lid of PDM one series 2 recently. This Philips bitstream dac sounds really big and powerful.

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Cool, it would be interesting to contrast and compare with the PDM3 (which I’m still really happy with).

That Philips bitstream chipset initially made CD palatable to me as a Naim user back in the late 80s. I’d borrowed a couple of low-end multi-bit/oversampling players (Philips CD160 & some budget Sony) and just didn’t get in with them in my admittedly ultra flat-earth vinyl Naim rig (Xerxes, 62, HiCap, 140, Kans), but the Rotel RCD965BX worked. It didn’t have the glare/edge I hated about the other (admittedly budget) players I’d had the opportunity to try. I’ve had a couple of 965BX pass through over the years and it still stands up as a very nice easy to live with player IMO. I also had a Marantz CD17KI for a while, and that was another very decent player. My systems have changed beyond any recognition over the years so sounds fine with pretty much any decent digital source and both systems are now multi-bit/oversampling (aforementioned PDM3 downstairs & Marantz SA8005 upstairs).
 
It's my favorite DPA-dac. On good recordings it's stunning. And it show that it's possible to make engaging sounding dacs without using multibit chips.
Some pages form a group test by NK in Hi-Fi Review September 1990, the Deltec PDM here used Philips SAA7320 or SAA7321 devices.

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Interesting, I didn't realise that DPA was still active in 2011...

When I was still a teenager I used to hang out at a dealer's lot. He was the national distributor for Audiolab, DPA, Monitor Audio and Roksan.
I got to listen to some of their early DACs a few times.
 
I’ve just come across a serviced DPM 1.3 at about the same price as I paid for a Rega DAC-R not long ago.

I was planning not to mess with the system for a good while, and the Rega is good, but the DPM DACs seem to have a stellar reputation.

Would the Deltec be an upgrade?
 
If you feel your Rega DAC sounds a little 'sterile' or 'thin' then I'd be tempted - otherwise no. I've had many DPA DACs and really liked the PDM series.
 
NeilK said:
If you feel your Rega DAC sounds a little 'sterile' or 'thin' then I'd be tempted - otherwise no. I've had many DPA DACs and really liked the PDM series.
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Thanks Neil. I wouldn’t say the Rega is thin, no. I’d imagined the Deltec might have a bit more precision or focus, given the level of engineering...

Sounds like a DPM2/3 or Bigger Bit might suit me better.
 
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Chaps, I need a hand diagnosing a fault on a newly acquired PDM 1 series 3 DAC.

It's fine when cold but after a couple of hours of warming up there is a 'sizzle' on the left channel. It's only there when the music is playing and is very apparent on quiet acoustic tracks.

The DAC has been poorly serviced with badly soldered and quite cheap Taiwanese caps on the analogue output side and there appears to be only a single original cap on the digital input PSU.

I seem to remember reading somewhere that hiss/ sizzle on a single channel is a sign of a dying tda1547 or tda1541. It would be very sad to write this one off as other than that it sounds gorgeous.

Thanks
 
Judging from a quick look at eBay those chips can still be found. Not cheap at £50 or so, but well worth doing if you are fairly sure of the diagnosis. They are DIPs too so even I can desolder/solder them (i.e. no need for a hot air station). Martin is one to ask though, he really knows these things.

PS My instinct, FWIW, would be to un-botch it, clean it up, recap neatly with decent components and see whether that moves things forwards. If the problem persists at least you’ve ruled out the past botch-job and can diagnose from there.
 
Tony L said:
Judging from a quick look at eBay those chips can still be found. Not cheap at £50 or so, but well worth doing if you are fairly sure of the diagnosis. They are DIPs too so even I can desolder/solder them (i.e. no need for a hot air station). Martin is one to ask though, he really knows these things.

PS My instinct, FWIW, would be to un-botch it, clean it up, recap neatly with decent components and see whether that moves things forwards. If the problem persists at least you’ve ruled out the past botch-job and can diagnose from there.
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Thanks Tony, I'm in total agreement

I'm not sure if those chips will be quite the same as a Philips original, more advice needed there.

Yes this is the ebay one from Suffolk, a calculated risk
 
PDM 1.3 uses a single Philips' SAA7350 ('DAC7') bitream DAC/decoder.
Look at the PSU caps and any botched decoupling caps for the source fo the sizzle first.
 
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