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Old 16th November 2007, 09:46 PM   #8391
RCruz is offline RCruz  Switzerland
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Hi

Finally lost the outboard dac (sony bla bla) and understand that I just started..

Actually The digital PSU is updated and the Analog just received the raygulator treatment (with some schottkys).

The output opamps are now LM4562NA and the sound is finally on par with the sony in terms of definition.. (I still miss the lateral dimension.. the sound is a little "smaller" now) but the timing and pace is much better.... This player can relly sound good..

The sound is much more coherent now (easier to listen to).

I am building new regs for the Analog psu... can I raise the output voltage to improve dynamics ?

How much will the LM4562 take ?

Regards

Ricardo
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Old 16th November 2007, 11:07 PM   #8392
RCruz is offline RCruz  Switzerland
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Quote:
Originally posted by Pars
Does your Meridian use coupling caps or is it DC coupled? If DC coupled, 22mV, while not high by itself, will be amplified by whatever gain the preamp (and power amp, if it too is DC coupled) have. Then it would be a problem.
I do not know how it is coupled.

What should be the problem ?

Whow can I identify the simptoms ?

Regards
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Old 17th November 2007, 12:55 PM   #8393
avr300 is offline avr300  Denmark
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Quote:
Originally posted by Thomo
Thanks for your comments guys. My volume pot is a 50k Alps Black Beauty. I sorted the connections but the volume is still really low and sounds odd. There's loads of detail and separation, so I know it'll be good in the end. What it is doing right, it is doing very, very right. Thanks for a great design Ray.

I think Mappo's labeled my resistors wrong, noobs. So I'll build another one soon.

Lee.
I took a quick measuring with my scope. Mine gives 2Vpp (actually 2.4Vpp) so it's comparable with the opamp filter.

I created a set of test tones with http://sourceforge.net/projects/wavb

Burned them, checked them with EAC wav analyzer that they were at 0db, and then I did the measurement.

Don't you have a DMM so you can check the resistors values ?
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Old 17th November 2007, 01:02 PM   #8394
Thomo is offline Thomo  United Kingdom
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Quote:
Originally posted by avr300



Don't you have a DMM so you can check the resistors values ?

Erm, yes. But I kinda rushed it as time has been a little limited and it had been sat all week almost finished and impatience got the better of me. I know I should have measured them. I am going to make another set of boards and do a "proper" one with premium parts.

Cheers,
Lee.
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Old 17th November 2007, 01:56 PM   #8395
Pars is offline Pars  United States
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Quote:
Originally posted by RCruz


I do not know how it is coupled.

What should be the problem ?

Whow can I identify the simptoms ?

Regards
It appears that you have a DMM? If it were me, I might do something like check DC offset at the output of the preamp with the CD player selected and on to see what that 22mV does further down the chain
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Old 18th November 2007, 02:12 PM   #8396
RCruz is offline RCruz  Switzerland
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Quote:
Originally posted by Pars

It appears that you have a DMM? If it were me, I might do something like check DC offset at the output of the preamp with the CD player selected and on to see what that 22mV does further down the chain
I have not removed the output caps on the CD53 so this offset does not enter the preamp. I am afraid to touch the inside of the preamp because it is an old Meridian 101 (30 years allways playing) and the cables might break.

Maybe I must replace the output caps with something better... I have two ELKO Visaton 470uF 63V bipolar caps... Can you advise on this replacement ?

Best Regards
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Old 18th November 2007, 02:20 PM   #8397
Pars is offline Pars  United States
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Quote:
Originally posted by RCruz


I have not removed the output caps on the CD53 so this offset does not enter the preamp. I am afraid to touch the inside of the preamp because it is an old Meridian 101 (30 years allways playing) and the cables might break.

Maybe I must replace the output caps with something better... I have two ELKO Visaton 470uF 63V bipolar caps... Can you advise on this replacement ?

Best Regards
You have 22mV of offset on the output of the CD player, AFTER the coupling caps? Yes, I would replace them with something like 47-100uf BlackGates (6.3V or 16V) NX or K series. Or film caps, but I am not sure how low you can go in value here without affecting frequency response.
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Old 18th November 2007, 02:26 PM   #8398
RCruz is offline RCruz  Switzerland
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Quote:
Originally posted by RCruz


Thank you Ray.... I added an output cap and now I have 12v sharp.

The 10uF is still parallel to the 1k05

Note:

I just replaced the opamps and want to remove the output caps.... but I have a 0.022V dc offset.

Can this value hurt my Meridian 101 PreAmp ?
Hi Ray

I finally have the rayregs built but as I could not get the values you indicated, I chose 120 ohm for R1 and 1047 for R2.

R2 is paralleled with a tant 10uF.

To stabilyze the output, I put a cap 16uF tant betwwen ground and +-12V output.

The output is now 12.25 Volts +-.

Can this hurt the opamps ?

Regards
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Old 18th November 2007, 02:35 PM   #8399
RCruz is offline RCruz  Switzerland
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Quote:
Originally posted by Pars


You have 22mV of offset on the output of the CD player, AFTER the coupling caps? Yes, I would replace them with something like 47-100uf BlackGates (6.3V or 16V) NX or K series. Or film caps, but I am not sure how low you can go in value here without affecting frequency response.

No the ofset is before the caps to ground. I believe this caps stop the 22mV getting out of the player.

Can I not use bigger output caps than 47 - 100 uF ?

Regards
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Old 18th November 2007, 03:04 PM   #8400
6h5c is offline 6h5c  Netherlands
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Quote:
Originally posted by RCruz
The output is now 12.25 Volts +-.

Can this hurt the opamps ?
No, 12.25V is no problem. Most opamps can handle +/- 15V easily.
Only AD8610 and 8620 have a maximum of +/- 13.5V.

Quote:
Can I not use bigger output caps than 47 - 100 uF ?

Regards
Yes, you could, but it's no use in this case. The lowest frequencies are already passed through perfectly with a 47...100u cap. And a bigger BG would only be more expensive.

Regards,

Ray
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