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
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
Member
Joined 2002
spwal said:
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.
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.
I suggest trying different speaker cables just to see if it changes the problem.
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?
jeff mai said:
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.
Member
Joined 2002
the word PATEKCLONE is what got me, cloning peters design is what i was commenting on, not the gain clone part 😀
J'
J'
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.)
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.)
Member
Joined 2002
john65b said:
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 ?
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
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
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 😉
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 😉
It looks like the DC power input cableis another way for RF to get into the amp.
In RF amplifiers where there is a strong desire to prevent RF from either entering or leaving the enclosure the power supply inputs are bypassed directly to the grounded metal enclosure using something called a feed-thru cap. See here:
http://www.surplussales.com/Feedthrus/FTsolder2.html
These caps are mounted in holes in the enclosure. The outer metal part of the cap is soldered directly to the enclosure (easiest to do with steel enclosure, but not impossible with aluminum).
If you can't easily add this type of cap, I would try to achieve the effect by connecting a cap, maybe 200-1000 pF, to each power lead coming into the enclosure, including the ground lead, to the enclosure. Put the caps as close as you can to the point where the power lead enters the enclosure and keep the leads as short as possible. Use ceramic or silver-mica caps.
It won't look pretty, but an amp that works always sounds better than one that doesn't.
You might want to check out a copy of the Radio Amateur's Handbook from your local public library. You'll find lots of useful info about minimizing the effects of RFI.
I_F
In RF amplifiers where there is a strong desire to prevent RF from either entering or leaving the enclosure the power supply inputs are bypassed directly to the grounded metal enclosure using something called a feed-thru cap. See here:
http://www.surplussales.com/Feedthrus/FTsolder2.html
These caps are mounted in holes in the enclosure. The outer metal part of the cap is soldered directly to the enclosure (easiest to do with steel enclosure, but not impossible with aluminum).
If you can't easily add this type of cap, I would try to achieve the effect by connecting a cap, maybe 200-1000 pF, to each power lead coming into the enclosure, including the ground lead, to the enclosure. Put the caps as close as you can to the point where the power lead enters the enclosure and keep the leads as short as possible. Use ceramic or silver-mica caps.
It won't look pretty, but an amp that works always sounds better than one that doesn't.
You might want to check out a copy of the Radio Amateur's Handbook from your local public library. You'll find lots of useful info about minimizing the effects of RFI.
I_F
Hi.
Had the same problems with my premium-kit after moving to a new flat (suddenly russian, german and french radio in my horns
).
Peter gave me a hint to install 300pf capacitor between inverting and non inverting chip input and as he says: problems are gone !
Michael
Had the same problems with my premium-kit after moving to a new flat (suddenly russian, german and french radio in my horns
).Peter gave me a hint to install 300pf capacitor between inverting and non inverting chip input and as he says: problems are gone !
Michael
You guys are unbelieveably helpful.
Thank you all so much. The builder has been silently following the thread and I hope that there is enough knowledge here to solve the problem.
What would we do without these wonderful international forums?
Thanks,
spwal
Thank you all so much. The builder has been silently following the thread and I hope that there is enough knowledge here to solve the problem.
What would we do without these wonderful international forums?
Thanks,
spwal
Hi,
My problem is not with a patek clone, but with a home made gainclone using the audio sector premium kit. I also have a radio noise. I will try the possible "patches" listed above, but I want to understand the cause of this radio noise to "solve" it.
Here is my setup.
Cambridge audio 540c v2 as transport
Monica 2 with the solid state gain stage
Passive preamp (serie shunt, with 10k as serie)
gainclone (no substitution or addition in the audiosector kit)
fostex design BLH fe103e
If I short the input of my gainclone I don't get any radio noise. Does this information help?
My rca cables are short approx 6 inches.
Here are some pictures: http://geocities.com/spacemen12/gainclone/
Also how does the radio get amplifier there? Is it AM or FM I am curious.
Thanks
My problem is not with a patek clone, but with a home made gainclone using the audio sector premium kit. I also have a radio noise. I will try the possible "patches" listed above, but I want to understand the cause of this radio noise to "solve" it.
Here is my setup.
Cambridge audio 540c v2 as transport
Monica 2 with the solid state gain stage
Passive preamp (serie shunt, with 10k as serie)
gainclone (no substitution or addition in the audiosector kit)
fostex design BLH fe103e
If I short the input of my gainclone I don't get any radio noise. Does this information help?
My rca cables are short approx 6 inches.
Here are some pictures: http://geocities.com/spacemen12/gainclone/
Also how does the radio get amplifier there? Is it AM or FM I am curious.
Thanks
Well, I tested mine at point blank range to 20w fm transmitter, a 500mw wifi unit, an open keyed CB radio, a microwave oven boiling water, and a GSM phone.
And, then I tried these:
Feedback: 22k 1/8w metal film
Inverting input: 680R 1/2w carbon film or Caddock carbon
Non-inverting input: 680R 1/4w carbon
Input impedance: From 10k to 22k 1/8w metal film (value depends on other factors, such as DC offset, layout, etc. . .)
A "speaker output zobel" located at the speaker jack--its unnecessary to have it effective during the audio band, as a "too small" zobel is better than none at all.
An additional load a the RCA jack, such as a small 100pF ceramic + 3R // 250k metal film, or just add a simple capacitor (load) of a size that has no effect on the audio band.
Whenever a capacitor, such as "input filter capacitor" has in-series resistance exceeding 470R, then add an additional small load.
47nF 100V Mylar capacitors, one each for V+ and V- (if audio effect is heard, then simply use a smaller value of mylar capacitor)
An RC for the secondary windings of the toroid transformer, or substitute a dual-bobbin EI core transformer (Either case its because you don't need every signal present on the power line).
And,
No accidental antennas present. . . Check out one of the popular antenna calculators here: http://bfn.org/~bn589/antenna.html
Its easy to dial in the frequencies in question, for instance, centerpoint of the FM band. Then you can use this to make sure that none of your cables are efficient antennas (inspire a little bit of inefficiency on the offending frequencies by making the cables the wrong length for an antenna). For instance, at 31" x 2 cables, I didn't receive a thing, but 28.5" x 2 cables tuned in the FM (so don't do that unless its a radio).
An FM tuner may (depending on design) promote radio into your amplifier if your pre/power amp cables are close to the radio's antenna.
EDIT: Its possible to use 3 conductor "outdoor extension cord" for speaker cables, so you can ground the woofer frame (that 3rd conductor).
Well, I hope some of that was helpful. I'm not so good in math, and while the ideas do work, please adjust the figures to suit your own application. 😉
And, then I tried these:
Feedback: 22k 1/8w metal film
Inverting input: 680R 1/2w carbon film or Caddock carbon
Non-inverting input: 680R 1/4w carbon
Input impedance: From 10k to 22k 1/8w metal film (value depends on other factors, such as DC offset, layout, etc. . .)
A "speaker output zobel" located at the speaker jack--its unnecessary to have it effective during the audio band, as a "too small" zobel is better than none at all.
An additional load a the RCA jack, such as a small 100pF ceramic + 3R // 250k metal film, or just add a simple capacitor (load) of a size that has no effect on the audio band.
Whenever a capacitor, such as "input filter capacitor" has in-series resistance exceeding 470R, then add an additional small load.
47nF 100V Mylar capacitors, one each for V+ and V- (if audio effect is heard, then simply use a smaller value of mylar capacitor)
An RC for the secondary windings of the toroid transformer, or substitute a dual-bobbin EI core transformer (Either case its because you don't need every signal present on the power line).
And,
No accidental antennas present. . . Check out one of the popular antenna calculators here: http://bfn.org/~bn589/antenna.html
Its easy to dial in the frequencies in question, for instance, centerpoint of the FM band. Then you can use this to make sure that none of your cables are efficient antennas (inspire a little bit of inefficiency on the offending frequencies by making the cables the wrong length for an antenna). For instance, at 31" x 2 cables, I didn't receive a thing, but 28.5" x 2 cables tuned in the FM (so don't do that unless its a radio).
An FM tuner may (depending on design) promote radio into your amplifier if your pre/power amp cables are close to the radio's antenna.
EDIT: Its possible to use 3 conductor "outdoor extension cord" for speaker cables, so you can ground the woofer frame (that 3rd conductor).
Well, I hope some of that was helpful. I'm not so good in math, and while the ideas do work, please adjust the figures to suit your own application. 😉
Thanks danielwritesbac,
Unfortunately, my technical knowledge prevent me to appreciate your explanations. Are you adding or they are substitution? Did you have the same problem before and it required all those "things" to get rid of this noise?
A zobel didn't solve my problem.
My noise come from near 96.9 MHz FM. There is no radio plug in the path. The only radio plug is on the same ac, but in another system.
The noise is not loud, I need to be really close to the driver to hear it.
Unfortunately, my technical knowledge prevent me to appreciate your explanations. Are you adding or they are substitution? Did you have the same problem before and it required all those "things" to get rid of this noise?
A zobel didn't solve my problem.
My noise come from near 96.9 MHz FM. There is no radio plug in the path. The only radio plug is on the same ac, but in another system.
The noise is not loud, I need to be really close to the driver to hear it.
Perhaps a small value capacitor, such as 100pF or 220pF, from + to - (a load) and located at the RCA jack (power amp input).
MiWi said:Hi.
Had the same problems with my premium-kit after moving to a new flat (suddenly russian, german and french radio in my horns
Peter gave me a hint to install 300pf capacitor between inverting and non inverting chip input and as he says: problems are gone !
Michael
Hi,
I will try the cap between the RCA hot and ground at the input. Also with this other solution cited above, which pins are the inverting and non inverting on this picture ( http://www.national.com/images/pf/LM3875/01144902.pdf ) ?
Thanks
It's been explained here how to fix it: http://www.diyaudio.com/forums/showthread.php?postid=1516522#post1516522
spacemen12 said:
This is the same approach either way. The 330pF cap directly across both of the chip's inputs (both inverting and non inverting inputs are marked on the PDF you've referenced) is a more effective solution. However, the 220pF positioned as a load (signal + to signal ground) at the RCA jack is an easier solution.
I had chosen a smaller value because, although its less effective, it has less effect on the audio band as well. Choose whichever size suits your needs. The most effective position is directly at the chip's pins.
Not every op amp has an RCA jack on the input. For instance, your CD player connects dac to onboard op amp directly on the circuit board. My suggestion will not work on this because there's no "jack" between the CD player's DAC and its output op amp. Yet, your source's onboard amp may be something you'd like to check out. Its easier to stop interference before it gets amplified.
However, Peter's suggestion works on op amps of all sizes.
So, consider it really worth your time to discover the input+ and input- pins for each op amp in your system (including your LM3875).
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