Mark Hammer's Forty Niner sounds gated...

[gigimarga]

Hello,

I've built a Forty-Niner tonight (thx Mark Hammer - it sounds very well!) and i had the same problem as here: http://www.diystompboxes.com/smfforum/index.php?topic=68652.0, a strong ticking.

After modding it as Mark wrote in the post, the ticking had stopped, but when i engage Anderton's booster the sound becomes very farty and gated...and as i can hear the on-off-on switch of the booster have a very subtle effect.

I am very angry of this problem, because i like it a lot...the last solution is to eliminate Anderton's booster and to use without it!

Thx a lot!

[R.G.]

Whenever someone says " xxxxxxx sounds gated (or farty)" the problem is always a biasing problem where the signal has to overcome some bias problem to be heard.

[gigimarga]

Thx for your reply R.G., but i know only to bias transistors, so, if you're kindly, here are my voltages (using a 9.10V battery):

IC1 (MC1458P) - SW1 on/SW1 off (boost switch)

01 - 4.58/4.58         08 - 9.10/9.10
02 - 4.58/4.58         07 - 8.35/4.51
03 - 4.42/4.42         06 - 4.18/4.53
04 - 0.00/0.00         05 - 4.18/4.53

IC2 (HCF4049UBE)

01 - NC           16 - 7.78
02 - 3.00         15 - NC
03 - 3.00         14 - 0.00
04 - NC           13 - NC
05 - NC           12 - 0.00
06 - 0.00         11 - NC
07 - 3.00         10 - 0.00
08 - 3.00         09 - 0.00

I'd built it using this PCB: http://gaussmarkov.net/layouts/49r/49r-project.pdf

Thx a lot!

[R.G.]

OK.

First - is it an etched PCB or perfboard?

IC1 is being driven into cutoff (pin 7 ->8.35V) when the boost switch is on. I don't know whether the schematic allows that or not, but that would cause gating.

IC2 is supposed to have power supply on pin 1, not pin 16. So pin 1 should be 9.1V. Pin 16 is a NC inside the 4049, so why it's at 7.78V is not clear. Pin 3 and pin7 of IC2 are tied to ground, but you show them at 3.0V. Something is wrong there. Likewise, pins 9/10 and 14/15 are used for active amplification. However, pins 9/10 are at 0V, and pins 14/15 show 0V and NC.

So your voltages do not match the layout in major ways.

[Lurco]

he says he used GMs PCB & he seems to count the pins the wrong way `round:
IC2s Pin#1 is the lower left on GMs layout pdf!

[R.G.]

In that case - which way is the chip really pointing? IC1 seems to be right, judging from the pin8/pin4 pair.

[gigimarga]

Something is strange here...i relooked on gaussmarkov's layout and it's very clear that the IC2 has the power supply on pin 1 and pin 16 is not connected

Anyway, if i don't use the booster it sounds ok, something like a Red Llama, so i think that the problem isn't here 

[gigimarga]

My apologies...on IC2 i count the pins in a wrong way...so the voltages are:

IC2 (HCF4049UBE)

01 - 7.78         16 - NC           
02 - NC           15 - 3.00         
03 - 0.00         14 - 3.00         
04 - NC           13 - NC           
05 - 0.00         12 - NC           
06 - NC           11 - 0.00         
07 - 0.00         10 - 3.00         
08 - 0.00         09 - 3.00         

[gigimarga]

Anyway, what can i do to prevent the cutoff of IC1?
I think that is something wrong with it on the powering...

[frankclarke]

Is R5 really 10k and really connected between pin 1 an 5 on IC1? Hard to believe such a big voltage drop across R5.

[R.G.]

I'm not sure what is causing it, but you are somehow getting a DC connection through the Sw1 section. When you put boost on, it causes the DC to be amplified and makes pin 7 go to the full supply voltage. I suspect the switch wiring.

You can test this theory by inserting a 1uF capacitor between SW2 and R7. That should stop the change in DC level on pin7.

[dschwartz]

why dont you just leave it like that and call it "Farty"-niner



sorry, i love jokes...

[gigimarga]

Thx a lot all for your answers...i will try them tomorrow and i will tell you the results...

[gigimarga]

For dschwartz: it's impossible to do what you said because i have only 3 another farty pedals, so i must to wait until i will another 5 

[gigimarga]

Mark Hammer built it some time ago and had put some clips with it on hammer.ampage.org...so, almost sure the problem is from the layout.

[gigimarga]

The Anderton's original schematic

http://www.diystompboxes.com/smfforum/index.php?topic=65585.0

http://www.diyguitarist.com/PDF_Files/FreqBooster.pdf

[gigimarga]

 

[gigimarga]

 

[gigimarga]

 

[gigimarga]

still not working well