Smashup Voltage [resolved]

[1026mind]

floor noise

 

[Paul Birkeland]

What amplifier are you using and what speakers are you using? (or alternatively how much gain does your power amp have any how sensitive are your speakers?)

 

[1026mind]

Cambridge Audio 851N one per channel and Klipsch La Scala clones that I build.

 

[Paul Birkeland]

Yeah, I figured you either had a ton of amplifier gain (20+dB) or highly sensitive speakers, and you have both!  I would use some Harrison Labs -12dB attenuators at the input of each amplifier to reduce sensitivity a bit, or consider a lower gain/lower power amplifier.

 

[1026mind]

Long time ago I purchased the last two suductor amps kits that you sold, would this work along with a Thorens turntable and the Eros that I build already?
t

 

[Paul Birkeland]

The Seductor will knock the noise down by about 12dB.  You may prefer the Seductor and some -12dB attenuators to really knock things down. 

 

[1026mind]

Got it, parts express have the atenuators they are 12db not -12db

 

[1026mind]

I went from 2 amps to 1 and the noise went down a little but I noticed that there is noise even without the smash powered up. its that normal?

 

[Paul Birkeland]

That is a bit abnormal.  You could try this mod:

https://forum.bottlehead.com/index.php?topic=11676.0

 

[1026mind]

Huge improvement, about 75% of the noise gone, the La Scala's really came to life!!!
Thank you very much!

 

[Paul Birkeland]

In your build where does the power supply connect to the chassis?

 

[1026mind]

everything goes to a grounding post.

 

[Paul Birkeland]

You have umbilicals in your build, so is each chassis plate connected through the umbilical?

 

[1026mind]

they are two umbilicals, one for the filament of the 4p1l's that is two wires and the other has 3 , one is ground and the other two are both 150v, one for each channel .

 

[Paul Birkeland]

so you have each chassis plate connected through the audio ground?

 

[1026mind]

yes Sir

 

[Paul Birkeland]

That is a potential source of noise.  Ideally you would have the chassis plates connected together through their own wire in the umbilical and that would be hard grounded to the E lug on the IEC power entry module, then the audio/power supply ground would run separately and you would put the antiphase diodes in the amp section between the audio ground and the chassis.

 

[1026mind]

audio ground would be the part where the RCA are connected to the ground?

 

[1026mind]

never mind my last comment

 

[1026mind]

just finished and its still a little buzz