Marantz CD63 & CD67 mods list

[higlander]

Originally Posted by Ben Hanke

....., then it might be time to think about getting a scope.

Right, get one and you can see where is the problem. I am using this one, cheap but serves the purpose well
ARM DSO203 Aluminium Nano 4 Channel Mini V2/Quad Pocket Digital Oscillo?scope.UK | eBay

[Ben Hanke]

Originally Posted by bull041161

Ok done it this is whats been done i have only upgraded the opamps rest was done when i bought the player. Detail is not bad but trebble is harsh and bass is not as deep as i would like the midrange is not so good eather. I have had a moded 67se before and i know what thay can sound like but this one does not do it

The most obvious thing I can see is that the wires for your output stage smoothing caps are far too long! Even worse, one twisted pair is running right past the transformer while the other goes over your output wires. I'd start by moving those caps right back to where they belong.

Secondly, your HDAMs are bypassed but not much else has been improved. I'm not sure of the correct order here but you'll definitely want to look at improving op-amp power and output stage filter caps. Check for DC on your output too.

Look to upgrade servo PSU and 5v pre-reg cap to bring back some bass... The list is endless though...

Oh, one last thing: Make sure your HA op-amps are the genuine article and not the all-too-common Chinese rip-offs.

Ben

[Ben Hanke]

Oh yeah, you also might want to sanity check that output stage PSU. Is it feeding the correct voltage and is it good quality and beefy enough for the job.

Thanks for the tip, Brent. Do you think it was interference between the transformers themselves or the effects of them being wired to the PCB together? I still have longish wires on my servo transformers so can move it away and see if it helps. The output tx is mounted to the original KI bracket.

[Fidelity Audio]

I think it is the diodes / regs etc being too close to what ever tx you have fitted in that area.

Brent

[bull041161]

Originally Posted by Ben Hanke

The most obvious thing I can see is that the wires for your output stage smoothing caps are far too long! Even worse, one twisted pair is running right past the transformer while the other goes over your output wires. I'd start by moving those caps right back to where they belong.

Secondly, your HDAMs are bypassed but not much else has been improved. I'm not sure of the correct order here but you'll definitely want to look at improving op-amp power and output stage filter caps. Check for DC on your output too.

Look to upgrade servo PSU and 5v pre-reg cap to bring back some bass... The list is endless though...

Oh, one last thing: Make sure your HA op-amps are the genuine article and not the all-too-common Chinese rip-offs.

Ben

Thanks ben im up to changeing a few caps and shortening them wires on the power supply caps but not really any good at this sort a thing. Did you notice the wires comeing from one of the input sockets on back as that is were another power supply is pluged in not sure what it poweres but its cb 14v dc power supply im useing

[Ben Hanke]

I noticed them. I'm assuming they're for the output stage. What power supply are you using exactly?

Also, this is probably obvious, but make sure those caps are wired the right way round. I imagine you would've had one pop by now if they were wrong, but that pink twisted pair carrying DC is an accident waiting to happen.

[bull041161]

Originally Posted by Ben Hanke

I noticed them. I'm assuming they're for the output stage. What power supply are you using exactly?

Also, this is probably obvious, but make sure those caps are wired the right way round. I imagine you would've had one pop by now if they were wrong, but that pink twisted pair carrying DC is an accident waiting to happen.

Hi ben its cb 14v dc 5 amp power supply. Im going to sort the power supply caps tommorow but i will let you know the value and make as thay might not be best for the job

[Ben Hanke]

CB as in radio? If so then I'd say it's very likely not up to the job. You want a good quality dual linear regulated power supply with a high VA rating. The original 7812/7912 regs have been removed from your player, so your op-amps are entirely at the mercy of whatever noise and ripple is present on that external supply. Brent sells some very nice looking, well spec'd external PSUs.

Alternatively you could go back in the box, but you're at a disadvantage there with everything being ripped out already so I wouldn't recommend it personally. If you've already broken out the box then I'd say roll with it.

[bull041161]

Originally Posted by Ben Hanke

CB as in radio? If so then I'd say it's very likely not up to the job. You want a good quality dual linear regulated power supply with a high VA rating. The original 7812/7912 regs have been removed from your player, so your op-amps are entirely at the mercy of whatever noise and ripple is present on that external supply. Brent sells some very nice looking, well spec'd external PSUs.

Alternatively you could go back in the box, but you're at a disadvantage there with everything being ripped out already so I wouldn't recommend it personally. If you've already broken out the box then I'd say roll with it.

Hi ben yes its a cb radio power supply. Whats cheapest but fairly decent one ben. Could you post me a link to any on ebay please

[Ben Hanke]

I've actually got no idea where to get a cheap one that is good.
Personally I would probably just build one myself on veroboard from good components, as the basic circuit is fairly simple and can easily be found online. You'd need something in the order of some board + stand-off mounts, a decent toroid (e.g. Nuvotem brand from RS), a case, +/- regs, smoothing caps, an LED + resistor, switch, sockets, cables, fuse, rectifier/diodes. You can usually get pre-made bare PCBs on eBay to make it a bit easier.
If I wasn't confident to do that then I'd probably save up my pennies for something off the shelf like one of Brent's supplies, because it would at least be built with hi-fi audio in mind. Brent's are a bit more pricey but include low noise regs rather than your standard 78xx/79xx jobbies.