CD player with distortion. laser?

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#201
Right I have had the bonnet open again and the two chips are as follows:

On the little board: M37BA LF 353N
On the main board underneath: PMI OP275GP T9423 N19188

the other half is actually happy, as now I wont just keep buying new hifi every five minutes, but mod this one now and then, everyones happy.
 
#203
This is the data sheet for the single OPA604... NOT the one you want, yours is the dual 2604 but it's an identical opamp.
With the "don't believe all you read" have a look at the last section under "sound quality".

http://www.datasheetcatalog.org/datasheet2/2/04hz8dw0dwzt7ethry7uh4td04fy.pdf

To me, having tried several different types over the years, I still like this one as to me it's in some ways the most "coloured" having a really musical presentation... the most "analogue" if you like.

And remember these differences are subtle... you have to fit the parts and really listen for a while because it's so easy to have huge expectations or be biased into thinking this or that is better... and the only sure way to know is too listen to a wide variety of stuff.
 
#204
I understand completely what you are saying, having built many loudspeakers from cheap £100 ones to some that cost me £3000!! differences can be hard to explain. How I see it (or hear it of course) is the emotional level it takes me. I often sit down for hours on end in the dark with my music on and only appreciate the difference after a few hours, that instant difference is the "saleable" sound that manufacturers want you to hear at demos, its rubbish to me, all I care about is, does it sound 'real' and that takes extensive listening. If the vocalist singing would sound harsh if she were in your living room, I want it to sound harsh from my speakers.

So there are two opamps in the player then. What is the cap for then, and I take it that you mean to put it across the + and - points on the chip.

This is now getting exciting. I really want to get this tried out soon as.
 
#205
would you say the 2604 is the better for my tastes, sounds like ours are the same, I love the analogue sound, and would love a vinyl player (cant really afford one at the moment) I used to have a Roksan DP1 (the top loader) and that had a lovely analogue sound to it.
 
#206
"Exptensive" 🙂 Bit of both I think 😉

Two opamps... if that's all you can see then yes. Sounds right number anyway.

The cap... are you a neat solderer... 'cos the way I do it is to carefully bend the legs on the cap to be a neat short fit over pins 4 and 8 on the IC and solder direct to the chip. Done neatly it won't affect it's ability to go in a socket.
 
#207
You are going to have to try the 2604 for yourself... and it's worth getting the others as you can "mix and match" fitiing one of each in either position to really try and get the best sonics. I use an OPA604 (singles) and an AD845 in my Micromega and that works really well for me.
In my amp I use OPA2604.
 
#208
I am quite neat, yea. I see what you are saying, think that I can do that.
What does the cap do then?
Yea the speakers were designed by me and made by a very good cabinet maker in burr maple, using bandor drivers (bandor lady is a very good friend of mine still) I started a high end loudspeaker company, but unfortunately fell through due to finance (the guy funding it, his own business went belly up) but got some very good feedback from three of the best reviewers in the business, Paul Messenger being one. this was way back in 2001
Sorry drifted off topic then.
 
#210
The cap maintains a low impedance supply (no hf noise etc) right across the IC pins. Many high performance opamps (high speed) can be unstable if decoupling is poor. That's unlikely to be an issue here even without the caps... but they only do good. Connecting across the supply rather than supplies to ground stops that noise being injected into the signal grounds.

Many many years since I hmmm dad ! built speakers. They were Peerless 3 way system from Badger Audio... wonder what happened to them. They were big.
Currently use B&W 703's... magic.
 
#213
Caps... most important thing really is to get ones that physically fit. Nothing worse than oversized stuff with wires etc extended out, and actually that negates a lot of the benefit.

Radial caps have the leads coming out the same end, axials are a wire each end. Philips used to use axials a lot.

So look what's fitted, make a list of value and voltage and then look to decide. Go for 105 degree rating rather than 85 and stick to good names. The "pitch" refers to the lead spacing on radials, usually 2.5 mm for liitle 'uns and 5 mm for medium values but check them all and order appropriately.
 
#217
ordered some nice elna silmic II's for the replacement caps, and going to start with just the OP2604 for the op amps, just got the replacement caps for the PS at the mo, as the elna's are not cheap, but no point making a slight improvment, might as well go the whole hog.
 
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