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Old 29th March 2003, 03:39 PM   #61
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Default The new amp....

Hi Gauthier!!

Nice to ear from you!!
Quote:
I have tried the modifications you have proposed. I mean : Pot at the input C2 Shorted and R5 supressed.
Quote:
The result is clearly better. No saturation due to high input level anymore. The sound is sharper also, i thing.
Quote:
Well done, you where right.
I feel happy for yours results....
Maybe you can send a email for the company that produces this wonderfull piece of high end telling your experiences...and your solutions!


Quote:
I still have a quite high 50Hz noise in the speaker, but dificult to determine the reason why. Probably, this is generated (amplified) by the first stage, and now that i have no attenuation before the second one... I can hear it...
I strongly fell that this hum is a grounding problem...but just in case try to disconect C3 temporarily that goes to the magic eye and see if it desapear...
Quote:
Another question also is the quite low curent in the first stage (89v-86v)/1.5k=2mA this is low for such a tube is'n it ?
I haven't find any specs of the 2C51 tube in my tube manual...(a rarity tube !!)...but i think that 2mA don't look to bad!
Quote:
Anyway, it's better, and thank you.
Thank you to ...because you have trust me...
Many voices here donīt see any problem in the pot position!

Regards

And looking forward for more news from you!
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Old 29th March 2003, 04:03 PM   #62
Foes is offline Foes  Belgium
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Hi Jorge,
Happy to read you again

About the noise, I already have removed C3 because his max voltage was 40V or something else. I alse have remove the EM80, and is a bit better.
It could be indeed a groung loop or something like that but its quite difficult to fix sich a think on a PCB.
Also, the heaters of V3 and V4 are feeded in AC. As the power comes in 5 wires in the same harness, the is maybe a cross talk also...
About the input tube or other exotic tubes, can i siggest you the use of TDSL :
http://www.duncanamps.com/tdslpe/
Finaly, i don't agree with the idea to send a mail to Dared. They are stupid, they can go to hell.
Rgrds and thanks again,

Gauthier
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Old 29th March 2003, 04:37 PM   #63
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Default The hum...that comes from East...

Hi Gauthier...

Try to disconect the input (from CD) cables...and see if the hum desapear!!


Quote:
Also, the heaters of V3 and V4 are feeded in AC.
This is normal...no problem there!!
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Old 29th March 2003, 05:09 PM   #64
Foes is offline Foes  Belgium
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Default Impressed !

Hi Jorge,

I'm very impressed,

You 'are right, when i disconect the cables or even if i connect the inputs together with a cable, it bigins to produce this f... Noise...
I guess that the solution is to avoid to connect a source on the amplifier...
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Old 29th March 2003, 05:19 PM   #65
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Default the monobloc saga...

That's the reason i don't like monoblocs...

See you have to grounds in each monobloc conected together at the power suply...so when you conect the interconects as the CD as a comum ground...you build a hum loop...

Try to disconect the ground side of one of the interconects at one channel only...and see (listen) what hapen!!
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Old 29th March 2003, 11:49 PM   #66
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Default RE:the monobloc saga...

Hi,

Quote:
That's the reason i don't like monoblocs...
What's not to like about monoblocks?

They offer superior stereo separation amongst other things, I use and have built for cistomers many monoblock designs, poweramps, preamps in separate chassis, dual mono PSus you name it.

Not a single customer ever experienced a hum problem....

To the best of my knowledge, there's not a single reason why a monoblock or dual mono design would be the cause of any hum.

Naturally some knowledge on grounding schemes helps, in fact proper grounding is one of the key factors in good design.

Cheers,
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Old 31st March 2003, 03:28 PM   #67
Foes is offline Foes  Belgium
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Hi you all,

I don't really know if monoblocs are best or not. Personaly, i just see that it cause problems to me. It's indeed better whe interupting on of both groung in the cinch...
The is still a hum when i increase the volume, but lower. To investigate again.
THanks to Jorge for his advice...
Gauthier
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Old 6th April 2003, 05:26 PM   #68
Foes is offline Foes  Belgium
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Smile Happy !

Hi !

I have done the following modifications :
*interupted de ground on the input of one chanel
*moved the ground power supply connection from the top edge to a point near the preamp where all the grounds seem to be connected in star

The result is incredibly better in comparision to the begining.
Thanks to all,

Gauthier
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Old 6th April 2003, 05:30 PM   #69
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Default Happy end!!!

Hi Gauthier!!!

Cheers!!
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Old 14th April 2003, 05:40 AM   #70
holm is offline holm  Germany
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Default Volume Pot

... maybe the designer had some gain preset
device in Mind, not a volume control.

Holm
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