Commercial Gainclone kit- building instructions - Page 49

raypalmer · 31st January 2009, 08:59 PM

Quote:

Originally posted by canadino
Hi,
My fuse blow after I connected the amp boards. When I taste the rectifier board was all ok.
What's going wrong?

There's no accounting for taste...

Sounds like you've got P's and V's mixed up?

raypalmer · 31st January 2009, 09:24 PM

Here's a Q. Whenever my TV is switched on my amp hums. I did the necessary CSI work and determined it's not sending noise through the mains. The hum is induced through the interconnects. Evidently it's passing through my Wakonda into the amp which is sensitive to it. The LK100 I've replaced wasn't vulnerable to this.

I'm guessing the TV has a poor output stage and generates noise? Would this be through the input ground? A coworker suggested the tv may produce an unnecessarily high output voltage....

Thoughts?

Sparky OR · 1st February 2009, 08:46 PM

I taste 9v batteries, was never macho enough to taste power supplies

VictoriaGuy · 1st February 2009, 09:55 PM

Quote:

Originally posted by raypalmer
Here's a Q. Whenever my TV is switched on my amp hums. I did the necessary CSI work and determined it's not sending noise through the mains. The hum is induced through the interconnects. Evidently it's passing through my Wakonda into the amp which is sensitive to it. The LK100 I've replaced wasn't vulnerable to this.

I'm guessing the TV has a poor output stage and generates noise? Would this be through the input ground? A coworker suggested the tv may produce an unnecessarily high output voltage....

Thoughts?

Ray-
My guess would be ground loop problems. Most 'pro' audio/studio equipment has 'ground lift' switches fitted to avoid such problems.
I ran into a similar thing when I was trying to mate up a networked laptop to a stereo receiver. (and didn't solve the problem completely, so abandoned that idea for the time being).

Cheers
John

AndrewT · 2nd February 2009, 07:53 AM

But be careful.
Some dangerous "ground lift" switches break the Safety Ground connection.

The "ground lift" switch should bypass the Disconnecting Network between the Safety Earth and the Audio Ground.
This arrangement is safe in either position.

audio1st · 2nd February 2009, 08:37 AM

Hi Ray, you may need to isolate the RCA's from the chassis, (can't see isolation in your pic's).
I didn't mention it earlier as you had no problem. It is the norm to have isolating washers on the RCA's..

canadino · 2nd February 2009, 11:18 AM

I don't understand very well the difference between: Ci caps, I/P caps and coupling caps. Where to install them?

Goodbye.

AndrewT · 2nd February 2009, 12:03 PM

Hi,
the input cap in series with the input connection is often called all three of these names and also referred to as the DC blocking cap and High Pass filter cap.

Ci = a cap on the input.
I/P cap = input cap.
Coupling cap = a cap to couple two stages.
DC blocking cap = a cap to block DC that might exist between two stages.
High Pass Filter cap = the series cap before Rin to ground that creates a 6dB/Octave filter that rolls off the low frequency and allows the higher frequencies to pass.

They are all the same.

kierownik · 3rd February 2009, 09:36 PM

Hi guys
Do you recommend smaller value Ci cap if the channel is going to drive mid/tweeter only and higher value for bass? (like in Peter's 4 channel amp) Or should I just stick with 1500 uF only?(LM4780 amp board in parallel)

Peter Daniel · 3rd February 2009, 09:52 PM

And which cap do you mean by Ci?

31st January 2009, 09:24 PM	#482
raypalmer diyAudio Member Join Date: Dec 2008 Location: Burlington	Here's a Q. Whenever my TV is switched on my amp hums. I did the necessary CSI work and determined it's not sending noise through the mains. The hum is induced through the interconnects. Evidently it's passing through my Wakonda into the amp which is sensitive to it. The LK100 I've replaced wasn't vulnerable to this. I'm guessing the TV has a poor output stage and generates noise? Would this be through the input ground? A coworker suggested the tv may produce an unnecessarily high output voltage.... Thoughts? __________________ Wherever you go there you are.

1st February 2009, 08:46 PM	#483
Sparky OR diyAudio Member Join Date: Jun 2003 Location: Eugene, Oregon	I taste 9v batteries, was never macho enough to taste power supplies __________________ Wish I'd studied this stuff with as much interest 30 years ago!

2nd February 2009, 11:18 AM	#487
canadino diyAudio Member Join Date: Feb 2008	Caps I don't understand very well the difference between: Ci caps, I/P caps and coupling caps. Where to install them? Goodbye.

3rd February 2009, 09:52 PM	#490
Peter Daniel diyAudio Member Join Date: Jul 2002 Location: Toronto, Canada	And which cap do you mean by Ci? __________________ www.audiosector.com “Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC

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2nd February 2009, 07:53 AM	#485
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	But be careful. Some dangerous "ground lift" switches break the Safety Ground connection. The "ground lift" switch should bypass the Disconnecting Network between the Safety Earth and the Audio Ground. This arrangement is safe in either position.

2nd February 2009, 08:37 AM	#486
audio1st diyAudio Member Join Date: May 2005 Location: Foxton, CAMBS..	Hi Ray, you may need to isolate the RCA's from the chassis, (can't see isolation in your pic's). I didn't mention it earlier as you had no problem. It is the norm to have isolating washers on the RCA's..

2nd February 2009, 12:03 PM	#488
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, the input cap in series with the input connection is often called all three of these names and also referred to as the DC blocking cap and High Pass filter cap. Ci = a cap on the input. I/P cap = input cap. Coupling cap = a cap to couple two stages. DC blocking cap = a cap to block DC that might exist between two stages. High Pass Filter cap = the series cap before Rin to ground that creates a 6dB/Octave filter that rolls off the low frequency and allows the higher frequencies to pass. They are all the same.

3rd February 2009, 09:36 PM	#489
kierownik diyAudio Member Join Date: Dec 2008 Location: New York	Hi guys Do you recommend smaller value Ci cap if the channel is going to drive mid/tweeter only and higher value for bass? (like in Peter's 4 channel amp) Or should I just stick with 1500 uF only?(LM4780 amp board in parallel)

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