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Old 16th May 2009, 03:32 PM   #731
udailey is online now udailey  United States
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Try a few jumpers from the output of your CDPs DAC and take that straight to some new output caps then to new RCAs and give it a try
You remove the whole analog output section from your CDP. Chances are it will be wonderful. But you have to have either the output caps of DC blockers somewhere after this mod because the DAC can put out a few volts of DC.
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Old 16th May 2009, 05:03 PM   #732
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Hi Uriah,

one of this days I'll do something similar but in my case is more complicated since the dac is a balanced current output one...

Better would be to intercept the DSD stream like in this post...

but I'm not able to design such filter...
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Old 16th May 2009, 05:22 PM   #733
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Got question regarding DC offset for any one who got the answer...

Is it necessary to have 0mv DC offset to go for DC couple in Myref? How about 1.0mv or 0.1mv for example.....????

Secondly if we combine a 'passive' preamp like the Lightspeed, would there be a DC offset problem arise....???

Thanks
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Old 16th May 2009, 05:36 PM   #734
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Quote:
Originally posted by gabanyayaya
Got question regarding DC offset for any one who got the answer...

Is it necessary to have 0mv DC offset to go for DC couple in Myref? How about 1.0mv or 0.1mv for example.....????

Secondly if we combine a 'passive' preamp like the Lightspeed, would there be a DC offset problem arise....???

Thanks
If you have output caps in you CD player and/or your pre you already have no DC offset

Same thing for the passive pre, if you have output caps in your CD player you can DC couple MyRef.

As always, pay attention to other equipments you could connect, also them must have NO DC offset.

However the answer to 'how much DC offset is safe' it depends on the gain of the amplifier.

For example if you have 1mV DC offset and the ampli has a gain of 20 the output DC offest would be 20 mV that is safe.

Someone knows the MyRef gain?
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Old 16th May 2009, 06:18 PM   #735
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Quote:
Originally posted by ClaveFremen


If you have output caps in you CD player and/or your pre you already have no DC offset

Same thing for the passive pre, if you have output caps in your CD player you can DC couple MyRef.

As always, pay attention to other equipments you could connect, also them must have NO DC offset.

However the answer to 'how much DC offset is safe' it depends on the gain of the amplifier.

For example if you have 1mV DC offset and the ampli has a gain of 20 the output DC offest would be 20 mV that is safe.

Someone knows the MyRef gain?

Output cap on CD player........!!!! I think all CDP got an output cap right...??? So there's no DC offset.....the passive pre like the Lightspeed did't have any hence no DC offset since considering the output of the CDP is protected....am I wrong here???

So Dario this mean 20mV from your example is a bad or good ?
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Old 16th May 2009, 06:34 PM   #736
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Quote:
Originally posted by gabanyayaya
Output cap on CD player........!!!! I think all CDP got an output cap right...??? So there's no DC offset.....the passive pre like the Lightspeed did't have any hence no DC offset since considering the output of the CDP is protected....am I wrong here???

So Dario this mean 20mV from your example is a bad or good ?
Yes, quite all CD players normally have output caps or DC servos but it's always safer to to measure it with a multimeter...

For Gainclones usually an output DC offset of 100mV is considered safe.
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Old 16th May 2009, 07:14 PM   #737
udailey is online now udailey  United States
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with your amp running you can measure the offset from the amps outputs. Where you connect the speakers. Just put the dmm there on ground and signal to speakers and measure. Some people have got as low as 3mV with DC couple which is awesome. I read somewhere that anything under 50mV is pretty good and you shouldnt hear it either. 100mV is probably okay to. DC will cook your speaker so thats why we want very little to none of it. In order to test this you should turn everything on and have a song playing or a tone.
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Old 17th May 2009, 03:41 PM   #738
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Quote:
Originally posted by ClaveFremen


Yes, quite all CD players normally have output caps or DC servos but it's always safer to to measure it with a multimeter...

For Gainclones usually an output DC offset of 100mV is considered safe.

thanks for the advice....



Quote:
Originally posted by udailey
with your amp running you can measure the offset from the amps outputs. Where you connect the speakers. Just put the dmm there on ground and signal to speakers and measure. Some people have got as low as 3mV with DC couple which is awesome. I read somewhere that anything under 50mV is pretty good and you shouldnt hear it either. 100mV is probably okay to. DC will cook your speaker so thats why we want very little to none of it. In order to test this you should turn everything on and have a song playing or a tone.
Uriah

Uriah, is it possible running 2 input rca in each channel....one with connection to input cap and the second one without filter cap (short wire to amp)....??? This sort of channeling the DC offset to somewhere else......if possible

I head this from your previous comments regarding DC offset in Myref......


BTW I still haven't got the bridge rectifier yet (621-GBJ804-F)....anybody care to help me with this...???
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Old 17th May 2009, 05:08 PM   #739
AndrewT is offline AndrewT  Scotland
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Hi,
tolerance to output offset is very much affected by the sensitivity of the driver and the Xmax of the driver.

Some drivers will not perform well with ~100mV of offset and others will do OK.
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Old 17th May 2009, 05:09 PM   #740
udailey is online now udailey  United States
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I am not entirely sure what you mean but I would put each RCA signal through an input cap if you measure any DC from your CDP. A poorly constructed preamp can give some DC if its active and a poorly constructed passive pre can make noise but I dont think its going to generate any DC. If you have no ouput caps on your CDP then your amp should have them. A CDP can give a few volts of it without a cap in the way of DC on each channel. This would destroy your speakers quickly. So measure then make your choice. Dont try to figure it all out first. Measure then decide.
Please email me the parts you would like again and I will order from Mouser for you today.
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