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Old 1st December 2006, 08:18 AM   #4901
poynton is offline poynton  United Kingdom
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Quote:
Originally posted by rowemeister


Some people beleive very firmly in attenuating the cd output.

'How do I cure that hard ‘CD’ sound?'

Quote:
Originally posted by AndrewT

this sounds more like a better matched set of input/output impedances rather than better with a preamp.

Passive attenuator is difficult to get performing well if the source and receive impedances are dancing all over as you adjust volume.

The pre-amp if designed correctly is basically a buffered volume control and a switch.
Hi.

The RA advert is really 'snake oil' to solve a proble which is not there !!!

How many modern amps/pre-amps have an Aux / CD input with a sensitivity of 150mV ?? Even my long-departed Quad33 had adjustable sensitivity.


I agree entirely with AndrewT.

If there is an input/output mismatch, you will never get good sound.

Andy

Edit :- I use an Alps Blue to control the volume of my system.
OK for the moment but will probably replace when funds permit with a stepped attenuator. Rebuilding the Garage/workshop takes priority.
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Old 1st December 2006, 08:28 AM   #4902
poynton is offline poynton  United Kingdom
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Default Re: cd6000 not so good anymore

Quote:
Originally posted by Luke


Since all this work has been done the player now skips.


Is there any way of testing the laser or adjusting the voltage.

Hi.

I am sure nobody was deliberately ignoring your pleas for help. I go away for a day and there are so many new posts, it is easy to overlook one.

I have repaired a couple of CD6000s. The HF board under the CDM causes a lot of problems - chip failure.

There is no way to adjust the laser but as you have a CD67, you could swap over the mechs to see if the situation improves (obviously not the HF boards) Also check the HF connector for a good contact - swap ends.

EDIT :- Also clean all the grease off the rails of the CDM. It sometimes goes a little hard and 'sticky' preventing free movement of the mech. Do not regrease.

Andy
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Old 1st December 2006, 08:31 AM   #4903
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1) My Marantz KI amp is 150mV (my nad at work is 165mV)

2) I do have better sound with the attenuator fitted. Much more dynamic and open with no loss from the sound I had previous (if it did it would be removed)

3) I am also experimenting with the correct values to use (lowest res value without affecting the cd output)

4) Try it!

Brent
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Old 1st December 2006, 08:56 AM   #4904
Luke is offline Luke  New Zealand
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Thanks Andy:-)
Its bedtime here, so will try your suggestions this weekend.

arthur
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Old 1st December 2006, 08:58 AM   #4905
SimontY is offline SimontY  United Kingdom
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Quote:
Originally posted by Will

Hi Simon,
Have you tried a TVC before ? It'll change your mind about active preamps forever....

cheers..
Hi Will,

No I have not tried one, yet. I have often heard it's one of the best ways to go, so I am curious, but put off by the cost.


Quote:
Originally posted by AndrewT

Simon, this sounds more like a better matched set of input/output impedances rather than better with a preamp.

Passive attenuator is difficult to get performing well if the source and receive impedances are dancing all over as you adjust volume. But, it is possible with certain combinations.

Adding buffers before and/or after the volume help tremendously at correcting the required impedances.
Hi Andrew,

Yes, I'm aware that you need a buffer, which is virtually a preamp anyway, just with a little gain! It's still an extra stage to pass the signal through. I do not use loads of gain, but I also need the preamp/gain functionality for at least one other input (soundcard).


Quote:

Will,
what's a TVC?
I believe it stands for Transformer Volume Control, but I could be mistaken! I think the advantage is that it takes care of impedances without introducing additional stages ie. it gives the best of "both" worlds.

Simon
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Old 1st December 2006, 09:29 AM   #4906
Will is offline Will  Malaysia
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Quote:
Originally posted by SimontY


Hi Will,

No I have not tried one, yet. I have often heard it's one of the best ways to go, so I am curious, but put off by the cost.




Hi Andrew,

Yes, I'm aware that you need a buffer, which is virtually a preamp anyway, just with a little gain! It's still an extra stage to pass the signal through. I do not use loads of gain, but I also need the preamp/gain functionality for at least one other input (soundcard).




I believe it stands for Transformer Volume Control, but I could be mistaken! I think the advantage is that it takes care of impedances without introducing additional stages ie. it gives the best of "both" worlds.

Simon

Hi Simon,
It's not that expensive if you purchase from here:

http://www.promitheusaudio.com/tvc.htm

Trust me, it's one of the things you won't regret. I have 1 and it is a revelation. This TVC has killed many so called hi-end preamps.


Hi Andrew,
Yes it's short for Transformer Volume Control. Basically it minimises losses in energy unlike resistive based volume control. Reduction in voltage gains are converted to current, so even though at low volumes, there is still a considerable amount of body in the music - instead of being thin.


cheers..
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Old 1st December 2006, 10:12 AM   #4907
SimontY is offline SimontY  United Kingdom
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Quote:
Originally posted by Will
Hi Simon,
It's not that expensive if you purchase from here:

http://www.promitheusaudio.com/tvc.htm

Trust me, it's one of the things you won't regret. I have 1 and it is a revelation. This TVC has killed many so called hi-end preamps.
Will,

Thanks for the link, it looks like a product born out of a love of music. I don't really want a whole product though, I'd like to make my own "preamp". I will be looking into a TVC at some point down the road. I don't need any more convincing

Back to the topic at hand, isn't it interesting that Audiocom's top CD63KI mods package comes with output transformers??
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Old 1st December 2006, 10:32 AM   #4908
awpagan is offline awpagan  Australia
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Quote:
Originally posted by SimontY


Will,

Thanks for the link, it looks like a product born out of a love of music. I don't really want a whole product though, I'd like to make my own "preamp". I will be looking into a TVC at some point down the road. I don't need any more convincing

Back to the topic at hand, isn't it interesting that Audiocom's top CD63KI mods package comes with output transformers??

I need convincing.

transformers can be wound fairly tolorance.
specially made for specific tolarances to match certain impedances at very high prices.

change the input(source) or output(amp)
and the transformer is just a hunk of iron.

allan
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Old 1st December 2006, 12:30 PM   #4909
poynton is offline poynton  United Kingdom
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Quote:
Originally posted by SimontY


Back to the topic at hand, isn't it interesting that Audiocom's top CD63KI mods package comes with output transformers??
I haven't seen that, Simon.
Is it a new ad. ??

Andy
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Old 1st December 2006, 12:33 PM   #4910
AndrewT is offline AndrewT  Scotland
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Hi Rowe,
Quote:
which is best but there seemed to be more favour towards the 'T' over the 'L'. Some amp inputs did not like the resistor to gnd.
I am surprised you came to this conclusion.
Source impedance is one of the main factors in screwing up the carefully selected filters built into most amplifiers.

Similarly, unbuffered volume controls also screw up the impedance matches needed for those input filters, but even worse than a high source resistance.

Can I suggest you try just the Lpad and tell us which suits your system/ears.
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