TDA1549 - Marantz CD48 - diyAudio
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Old 29th March 2015, 01:13 AM   #1
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Join Date: Jun 2008
Default TDA1549 - Marantz CD48

Hello !

I've been out of this a long long time but have been listening to and enjoying my home built stuff with a sense of pride...that it all still works !
That said, I've been getting itchy feet recently but too afraid of disturbing my successful Arcam Alpha CD with a shed load of mods I decided to do a bit of reading to see what else was out there that I could cheaply muck around with.

Not sure what you lot think but..I like the Lampizator site and the narrative sometimes makes me laugh out loud and Fikus always attempts to tell the truth...as he sees it anyway..lol

Anyway he seems to rate any TDA1549 based CD Player as pretty much ' up there ' with some expensive ones as you probably know already and it really fired me up once I'd taken a look at the simplicity of them.

So I got hooked on the teachings of TDA1549 in the Phillips and Marantz machines and bought two CD48 players for 50 ( for both )

I downloaded everything, read the lot and finally stripped the horrible thing down to a single green main board.
The 1549 DAC chip is the V out type ( as opposed to current out ) which means we can use the clean signal of the output legs ( no 4 and 7 ) of the chip straight to the rca's via a couple of coupling caps.
OK....so this is nothing new and you clever ones knew this already maybe but today I actually got round to doing it - including removing the op amp. I really enjoyed removing the op amp for a change instead of ' rolling ' them. God knows how I've wasted money on that hobby...

I have listened to the player for quite a while and was surprised and impressed by the mids and treble initially but eventually found it a little forward and fatiguing compared to my very liquid and analogue sounding Alpha.

I'm pleased to say that this VERY simple mod ( 15 minutes - ish ) has jettisoned this player forward massively and so I've decided to apply several other changes to see how far I can take it.
I'll also be posting pics soon and some explanations of what I'm doing or trying to do if anyone is interested.

After all - this is how my Arcam Alpha came to be from reading the ' Arcam Alpha Mods ' thread from years back.

Please note : I'm no engineer, mathematician or clever sh... but have sufficient skills to implement additional improvements.

So, currently the CD48 has lost almost all of it's hf glare and a lot of the hardness in sound which I'm putting down to losing completely it's entire output stage of some 40 odd parts plus the crap dual op amp....
No loss in output either....same volume settings.
It sounds much better and is already matching my other machine in some if not many areas - no real analogue liquidity yet but I reckon I'll find it soon.

Next up is the diodes, all the caps, independent power to the DAC chip, improving the main but cheap 05 regulator which once powered the whole machine, eventually the clock and anything else I can think of...or you can think of if you have any advice.

If you've done one already please give me a steer....I reckon I'm on to something - and it's going to be cheap too !

Rgds

Andrew
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Old 29th March 2015, 10:44 AM   #2
Chivvyp is offline Chivvyp  United Kingdom
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Hi,

I did one a while back, used a flea to power the TDA1549 and uprated the caps in that area, seems the cap on the vref pin is an important one to do. Also tried to clean up the power supplies to other chips. I didn't bypass the opamp as you did but put another one in.

It was all sounding quite pleasant until i tried to fit a new clock during which it all stopped working, I destroyed 2 that way, odd as I've never had an issue fittingnew clocks in other players.

I've done similar with a CD5000 which uses the same chip (didn't bother doing the clock with that one) and used it as my main player for a log while until the tx that poers the flea broke (I have to get round to fixing it soon).

I may have a list of the changes that I made on my work PC, if I find it I'll post them on here.

Regards

Pete
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Old 29th March 2015, 12:03 PM   #3
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Quote:
Originally Posted by Chivvyp View Post
Hi,

I did one a while back, used a flea to power the TDA1549 and uprated the caps in that area, seems the cap on the vref pin is an important one to do. Also tried to clean up the power supplies to other chips. I didn't bypass the opamp as you did but put another one in.

It was all sounding quite pleasant until i tried to fit a new clock during which it all stopped working, I destroyed 2 that way, odd as I've never had an issue fittingnew clocks in other players.

I've done similar with a CD5000 which uses the same chip (didn't bother doing the clock with that one) and used it as my main player for a log while until the tx that poers the flea broke (I have to get round to fixing it soon).

I may have a list of the changes that I made on my work PC, if I find it I'll post them on here.

Regards

Pete
Yes Please Pete - that'd be a great help !!

If it was in your main system for a while you must have liked it then....I am really quite surprised by what it's doing already and also why this 1549 chip never got the attention the 1541A got - I love this old chip btw.
Your clock issue is rather worrying though - I've seen your posts for years and you know your ' stuff '
Did you ever work that mystery out ?

Hey, thanks for the reply

Andrew

Last edited by AndrewGM; 29th March 2015 at 12:05 PM. Reason: spelling
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Old 30th March 2015, 08:18 AM   #4
Chivvyp is offline Chivvyp  United Kingdom
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Join Date: Apr 2006
Location: London
Here you go

New 5v supply to dac chip
Disconnect link 9117 and add new supply nearest to 2337
Consider removing 3 fusible resistors
Replace 2331 digital with Oscon
Replace 2333 analog, 2335 opamp with better
Possibly replace 2310 with something better
As such pay attention to whatever cap is fitted on pin 8 - which filters the internal voltage reference. Marantzx have probably used a cheap electrolytic. Replacing this with a good small film cap (Wima MKS2, 3.3-10uF ) or Sanyo Oscon again, 10uF or so would be a very good idea... it'll clean things up no end.

Dac to outputs
Replace 2302, 2303 with BGs
Replace opamp
Replace opamp power caps 2337 and 2339 with better
Remove 2308/9 output filter caps
Remove 3376/3377, 3366/3367, 3364/3365, 7364/7365, 7362/7363 disables the headphones and mute circuit if you don't need - check dc output though.

Replace 2100 2n2, 2101 47p with better, I used Vishay MKP1837

Main supply
Replace 7805 voltage reg with superrayreg
Replace 2536 with 8200uf, bypass with 47uf
Replace 2538 with 4700uf, bypass with 47uf
Replace Diodes 6535 > 6538 with Schottky

Over time I also did various other small mods (like replaced the various bypass caps on the 5v feeds to the main chips with some bigger electrolytics placed under the board) but I didn't make a record of those.


Hope it helps.

Never got to the end of the clock problem, it may be that I had a faulty clock. After I removed all the clock related parts and attached the new clock it didn't work, when I replaced all the original clock parts it still didn't work, could be I broke something else unrelated during the work but I gave up on it then. TBH I never found any information on anyone who did replace the clock so I really don't know if it would have improved things with this player or not.

Regards

Pete
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Old 30th March 2015, 08:42 AM   #5
Chivvyp is offline Chivvyp  United Kingdom
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also, the tx in the CD48 is very weedy (IIRC).

On my cd5000 I added a small tx for the flea that powers the dac and added a bigger 10v toroid for the main supply. The original tx is just used for powering the display now.
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Old 31st March 2015, 12:33 AM   #6
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Thanks Pete - excellent list.
There's plenty to think about there - in fact there's loads of stuff I never thought about too.
No wonder your machine sounded good !

Better start taking some photos now before it becomes unrecognisable

Much appreciated

Andrew
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Old 31st March 2015, 07:56 AM   #7
Chivvyp is offline Chivvyp  United Kingdom
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Join Date: Apr 2006
Location: London
Good luck,

I'll be interested to hear how you get on and how you find the sound quality as you go. With my 5000 I didn't find that it shone or was weak in any particular area, it was just very pleasant to listen to.

The TDA1549 seems to have been very short lived and not used in many original machines for some reason, maybe one of the reasons that more people haven't played with it.

Pete
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Old 2nd April 2015, 08:55 AM   #8
Chivvyp is offline Chivvyp  United Kingdom
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BTW Andrew, what are you using as coupling caps?

Regards

Pete
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Old 2nd April 2015, 09:50 AM   #9
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Hi Pete

At the moment I have 2.2 uf Clarity Caps in place but have some better spec Auricaps to try and some copper clad Obbligato's I've had for years I might have a go with.

Just waiting for 11DQ10's, oscons and main ps caps to arrive before I can get on with the work but having two CD48's means I can play and listen at the same time..! The half modded machine sounds great....I can still hardly believe what's happening already. If I can eek some extra oomph out of it in the bass and calm the hf down just a tad it may well take top spot in the main system.

When I think about the 6 month labour of love my Arcam was then consider what the CD48 is doing after a 15 - 20 minute bodge job it's all rather embarrassing !

Don't you just love this hobby
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Old 4th April 2015, 12:44 PM   #10
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Think I've attached a pic of main board so far.

Few Oscons in place plus Pan FC. I've lifted the legs of the .1uf caps around the dac chip which are to be replaced with some tin foils. The original little caps used in this player look like tiny resistors - never seen anything like it before. Where did they come from ? Odd indeed.

I've also a few 3r3 Shinkoh resistors left from another ' over the top ' idea from years back so I'll put them in as the 3 x 5v carriers to the dac chip after the LM317 regulator is in - for the dac power.
Bigger main ps caps and fast / soft diodes not here yet - frustrating - got some tants to put in, another ps for the 7350 and I'll be close.

Bit of case damping - plank of wood glued to the base ( done nicely btw ! ) and it should be pretty decent.

I've a pic of my other CD48 playing away to itself that has the dual op amp removed and the signal straight off the Dac chip to rca's to load next.

Still staggered by the performance of this - even with original horrible bits still in place - like nothing else done to it.

Post that later....
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