PLEASE HELP: SERIOUS fm radio through my patekclone

[spwal]

Hi,

This is my second clone built by a highly respectable builder. Both had this problem to the point where i returned the first one.

I hear the FM radio very prominantly thorough my speakers 97db efficiency. my friend as well as the builder can barely hear it. It is a fantastic amp except for the godforsaken radio noise.

What to do? He has suggested increasing the capacitance to solve the problem.

Others here have suggested shielding... Im not too sure that will do it, the last one was enclosed, this one is naked.

Are there more effective ways to ground than others?

When I move my speaker wires away from each other the radio noise *seems* to get softer, could be imagination.

I am using those solid core paul speltz anti-cables.

FYI: I did not have this problem with my 45 SET amps, my real Aleph 3, my Aleph Miniclone, or other amps I have owned.

This is a cost-is-no-object project and im real frustrated that it isnt working amazingly well.

I can turn the amp up and it is amazing, but at lower volumes its like a competition between the radio and my speakers.

PLEASE HELP!

The amp is on the way back to him for diagnosis.

Thanks!

Spwal

[jleaman]

Originally posted by spwal
Hi,

This is my second clone built by a highly respectable builder. Both had this problem to the point where i returned the first one.

I hear the FM radio very prominantly thorough my speakers 97db efficiency. my friend as well as the builder can barely hear it. It is a fantastic amp except for the godforsaken radio noise.

What to do? He has suggested increasing the capacitance to solve the problem.

Others here have suggested shielding... Im not too sure that will do it, the last one was enclosed, this one is naked.

Are there more effective ways to ground than others?

When I move my speaker wires away from each other the radio noise *seems* to get softer, could be imagination.

I am using those solid core paul speltz anti-cables.

FYI: I did not have this problem with my 45 SET amps, my real Aleph 3, my Aleph Miniclone, or other amps I have owned.

This is a cost-is-no-object project and im real frustrated that it isnt working amazingly well.

I can turn the amp up and it is amazing, but at lower volumes its like a competition between the radio and my speakers.

PLEASE HELP!

The amp is on the way back to him for diagnosis.

Thanks!

Spwal

You have cloned Peter Daniels design ? or you built something similar ?

Posting pictures might help, but i don't know if any one will help you after cloning his design.

[jeff mai]

What? Isn't Peter's design sort of a "clone" itself?

I suggest trying different speaker cables just to see if it changes the problem.

[BWRX]

A schematic of the amp in question would be helpful. What other equipment is in your system? What is the physical arrangement of your equipment? How is everything wired up?

[BWRX]

Originally posted by jeff mai
What? Isn't Peter's design sort of a "clone" itself?

I was thinking the same thing. It's a chip amp. The circuit probably isn't anything special, it's the way Peter packages his designs that are unique.

[jleaman]

the word PATEKCLONE is what got me, cloning peters design is what i was commenting on, not the gain clone part

J'

[john65b]

I have the same problem with my point to point Gainclone - I was having some motorboating issues and turns out it was my cellphone. Before a call would come in, putt putt putt....

Try different source input cables and/or shorten your the cables as short as you are able, and same with the speaker wires.

Also try the amp on an isolated wiring circuit (no fluorescent lamps, washing machines, TV, etc.)

[jleaman]

Originally posted by john65b
I have the same problem with my point to point Gainclone - I was having some motorboating issues and turns out it was my cellphone. Before a call would come in, putt putt putt....

Try different source input cables and/or shorten your the cables as short as you are able, and same with the speaker wires.

Also try the amp on an isolated wiring circuit (no fluorescent lamps, washing machines, TV, etc.)

You must have a GSM cellphone then, all gsm cell phones do that even mine does..

I would change the cables and also check your grounds see if you can test your mains ground too. Maybe a isolated power bar ?

[I_Forgot]

Changing cables does not solve the problem. It is at best a band-aid approach. The amp should work fine without RFI problems no matter what cables you use.

That said, it is sometimes nearly impossible to fix the problem depending on where you live- i.e. if you are in very close proximity to a commercial broadcast station, the field strength may be so high that the RF is going to leak past anything you do to stop it. My parents live in such a location.

Since you have had other amps that work fine the problem is in the construction of this particular amp. The RF can get in at the amp's input and at the output. To stop RF at the input, using shielded cable, a enclosed metal case, and proper grounding techniques (star ground, etc.) is step 1. You can try adding ferrite beads to the "hot" side of each input, and maybe a small capacitor across each input to ground.

Try installing a parallel LR in each output as shown in the application notes on the amp chip. The inductance will reduce high frequency energy getting back into the amp. It will have the added benefit of increasing the amp's stability. This network frequently gets left out by amateurs who feel the amp must sound better without it, and many of them can get away with it because they live in a low RF environment, but try connecting some odd-impedance speakers or turn the amp on near a radio broadcast tower and you have the sort of problem you are experiencing or worse.

I_F

[Peter Daniel]

If the amp is built exactly as per pictures posted here: http://audiosector.com/chassis_patek2_amp.shtml it should not create any problems.

I once had a customer who had some radio frequecy interference, and interestingly, he was also using anti-cables. Since he requested longer than usual umbilical cord and had high output connected to a subwoofer amp as well, I couldn't really be sure what was actually causing the problem. That was about the only case when someone complained about radio frequency pickup.

Beside that single case, some people commented on popping noises caused by electric switches in a house (lights, refrigerators or air conditioning), mostly in Florida area, but there was also one person in New Zealand. After that I started installing 300pf capacitor between inverting and non inverting chip input and problem was gone.

However, during a recent testing, I noticed that this capacitor slightly affects amp perfomance by putting a bit of vailing on immediacy aspect of sonic signature, so if possible I would prefer not to install it.

The reason I posted the detailed pictures on my site was actually to make it easier for people to copy that design, for personal use of course