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Buffer pop

PostPosted: 28 Apr 2009, 21:56
by fastfrets
Hi, I built this buffer sounds great, but now all my true bypass pedals after it pop when switched! Why is this?

Thanks

Re: Buffer pop

PostPosted: 28 Apr 2009, 22:28
by Fuzzer
The 10 [uF] capacitor might be leaking current, put a 1M resistor from the output to ground.

Re: Buffer pop

PostPosted: 01 May 2009, 23:24
by mdaudet
Hi.

I've experienced the same issue as you. A big resistor as a "pull down" would not fix the problem (eg. 1M, 2M2, etc). The POP is in other TBP pedals after de buffer, a LOUD pop.

What I did?

Simply put a SMALL resistor as the same way you put a "pull down" one, In my case, a 1K resistor fixed my problem. No more pops in my TBP pedals. The thing is that you don't want to keep the capacitor charged all the time, so a small flux of electrons must find a way down to ground. The Small resistor does it.

You could try a Pot, e. 10K, wired as a variable resistor to ground and find the sweet spot (in order to keep the output impedance low). When your other pedals stop popping, set the resistance and replace it with a fixed one. If you don't want to do that, just put a 1K in that place.

Tell us your results.

cheers.

Matt

Re: Buffer pop

PostPosted: 01 May 2009, 23:28
by lolbou
But you create a filter with the output cap that way? No sound issue?

Re: Buffer pop

PostPosted: 02 May 2009, 00:28
by Fuzzer
mdaudet wrote:Hi.

I've experienced the same issue as you. A big resistor as a "pull down" would not fix the problem (eg. 1M, 2M2, etc). The POP is in other TBP pedals after de buffer, a LOUD pop.

What I did?

Simply put a SMALL resistor as the same way you put a "pull down" one, In my case, a 1K resistor fixed my problem. No more pops in my TBP pedals. The thing is that you don't want to keep the capacitor charged all the time, so a small flux of electrons must find a way down to ground. The Small resistor does it.

You could try a Pot, e. 10K, wired as a variable resistor to ground and find the sweet spot (in order to keep the output impedance low). When your other pedals stop popping, set the resistance and replace it with a fixed one. If you don't want to do that, just put a 1K in that place.

Tell us your results.

cheers.

Matt


The reason why your problem wasn't solved with the 1M resistor was because the capacitor was very leaky, it was very wasted.

With a 10k resistor, you're screwing up the input impedance of the next effect.

Re: Buffer pop

PostPosted: 02 May 2009, 17:40
by mdaudet
Fuzzer wrote:The reason why your problem wasn't solved with the 1M resistor was because the capacitor was very leaky, it was very wasted.

With a 10k resistor, you're screwing up the input impedance of the next effect.


Tried with different caps with the same result. No matter the value, material (tantalum, electrolitic,etc), or if they're new or old, its always the same problem. To fix that, I added a small resistor. I know it affects somehow the impedance, but the main goal was to keep the highs through the cables and effects, in other words, to have more current (current gain = buffer) to help the signal flows through the cables. It works for me in a pleassent way.

Doing what I did, the difference between being connected directly to the amp or passing through a lot of effects (I got at least 8 TBP effects in my line, others are in the FX loop) is minimal. The primary goal was reached.

Course, if you have some ideas to fix the problem with an other perspective, believe me that I would be grateful. Thanks.

Cheers.

Matt

Re: Buffer pop

PostPosted: 02 May 2009, 18:05
by Fuzzer
Hmmm, weird stuff...

If it is working for you, well then it's fine. You're right, he Buffer gives more current drive, to keep from loading, but didn't you feel a volume loss compared to the scheme without the small resistor (with the pop happening)?.

Re: Buffer pop

PostPosted: 02 May 2009, 18:30
by mdaudet
Hi.

No, no volume loss or anything strange. This is not the first buffer I built that has the POP problem. Built the Super Buffer from Jack Orman, some simple buffers from GGG, another buffer ideas from me, etc. All those buffers needed a small resistor at the end to avoid pop in the rest of the TBP effects.

I guess with no TBP effects the output capacitor of the buffer is enough, because the input buffers of the fet switching effects (Boss, etc) blocks any DC coming from the buffer I've build.

Tried the buffer with the small resistor and bypassing it in order to test the effectiveness of the built buffer. The only thing I hear is that I recover the high loss when the buffer is ON, no volume loss or missmatch impedances.

I'd contact Jack Orman and he told me the same thing I came up with first (you too), the Pull Down resistor. In my experience with the buffer, the higher the value of the pull down, the higher the pop was. So, i think "backwards" with this principle: "If the PD Resistor is blocking the discharge of the capacitor on the signal, maybe I should let some discharging happens ir order to eliminate the excesive ammount of electrons keept in the capacitor". Very odd thinking, but it works. Because the current is flowing higher, no voltage increasing, the 10K resistor does not act like an "output level". I guess thats your question about.

Strange? Weird? yes, it is. Hopefully I fixed the problem and haven't experienced unwanted behaviour, only sparkle clean and a big smile in front of a mirror. Lot of pedals and cables, the same sacred TONE. hehehe

Cheers.

Matt

Re: Buffer pop

PostPosted: 03 May 2009, 04:00
by Fuzzer
mdaudet wrote:"If the PD Resistor is blocking the discharge of the capacitor on the signal, maybe I should let some discharging happens ir order to eliminate the excesive ammount of electrons keept in the capacitor". Very odd thinking, but it works.


Not odd, that's the way it works, the pulldown's purpose is to allow the discharge for every case, even if it's 1M.

Re: Buffer pop

PostPosted: 07 May 2009, 09:07
by distortion_gfx1
I have the same problem with my phase90 clone.. I've tried changing the value of the pull down resistor but still there's a popping sound.. then I change the 3pdt to 2pdt footswitch then suddenly the pop is gone... i just dont know why :?: :roll:

Re: Buffer pop

PostPosted: 07 May 2009, 09:42
by RnFR
distortion_gfx1 wrote:I have the same problem with my phase90 clone.. I've tried changing the value of the pull down resistor but still there's a popping sound.. then I change the 3pdt to 2pdt footswitch then suddenly the pop is gone... i just dont know why :?: :roll:

sounds like you might have an LED problem. i know it's written up on the AMZ site. you can find it on this page-
http://www.muzique.com/lab/main.htm

Re: Buffer pop

PostPosted: 24 Jun 2009, 07:07
by distortion_gfx1
RnFR wrote:
distortion_gfx1 wrote:I have the same problem with my phase90 clone.. I've tried changing the value of the pull down resistor but still there's a popping sound.. then I change the 3pdt to 2pdt footswitch then suddenly the pop is gone... i just dont know why :?: :roll:

sounds like you might have an LED problem. i know it's written up on the AMZ site. you can find it on this page-
http://www.muzique.com/lab/main.htm



tnx.. dude! :thumbsup

Re: Buffer pop

PostPosted: 24 Oct 2011, 06:32
by davidmochen
HI there,

I take it that you would add the 1K pulldown at the output, i.e., after the 10 uF cap, is this correct? I am trying to fix the same problem with the AMZ super buffer, which gives me huge pops when toggling it on/off and also when on, in the TBP pedals after it.

thanks

David

Re: Buffer pop

PostPosted: 27 Oct 2011, 03:57
by davidmochen
The 1K resistor at the output of my AMZ Super Buffer got 95% rid of the pop when engaging/disengaging the buffer. Just a very small click now. Haven't tried TBP pedals after it yet but I am pretty confident the popping will be reduced as well. This Super Buffer is impressive. I did some extrme tests such as using two long and crappy cables joined just with non shielded wire, even touching the "live" tip of the junction with my hand, and NO LOSS/NO NOISE at all. Impressive!!!

Re: Buffer pop

PostPosted: 25 Jun 2014, 15:54
by sgret612
davidmochen wrote:The 1K resistor at the output of my AMZ Super Buffer got 95% rid of the pop when engaging/disengaging the buffer. Just a very small click now. Haven't tried TBP pedals after it yet but I am pretty confident the popping will be reduced as well. This Super Buffer is impressive. I did some extrme tests such as using two long and crappy cables joined just with non shielded wire, even touching the "live" tip of the junction with my hand, and NO LOSS/NO NOISE at all. Impressive!!!


Hello!!!

Does it mean you added 1k resistor after output then connected to ground?

thanks.