Mad Professor Forest Green Compressor

ShortScaleMike · Post by **ShortScaleMike** » 12 Jan 2012, 08:51

Anyone aware of any decent sub suggestions for the AD797?

I'm guessing a 741 would be quite junky - what about a TL081? TL071?

pedalgrinder · Post by **pedalgrinder** » 12 Jan 2012, 10:29

you could try a ne5534 that would be fine. I like the lf351 i reckon they sound great my thats just my opinion others might think they sound ratshit. but theres a couple of options you could look or even check out the datasheets on.

ShortScaleMike · Post by **ShortScaleMike** » 12 Jan 2012, 11:13

Mnay thanks, I can get hold of the NE5534 so I'll give that a shot.

deltafred · Post by **deltafred** » 12 Jan 2012, 12:00

It is a low noise low distortion jfet opamp so I would have thought that any jfet opamp would be suitable.

I read on one of the the hifi forums that it is not a very good opamp because according to one guy the oboe solo on a particular classical piece seemed to be played faster when using this opamap in a preamp as opposed to some other cork sniffery opamp.

Now that would be a pretty neat pedal to build if it works for guitar as well.

mictester · Post by **mictester** » 12 Jan 2012, 12:29

deltafred wrote:according to one guy the oboe solo on a particular classical piece seemed to be played faster when using this opamap in a preamp as opposed to some other cork sniffery opamp.
.

Do these idiots ever actually consider what they're posting? I have seen more stupidity and blinkered bias in a single page of a "hi-fi" forum than I've seen in the whole of FSB!

The funniest thing is that no matter how pure the output of your amplifier (and it's trivially easy to build really good semiconductor amplifiers), the loudspeaker will add (typcically) 5 - 10% distortion. These hi-fi morons claim to be able to hear the difference between 0.001% and 0.0001% THD....

pedalgrinder · Post by **pedalgrinder** » 12 Jan 2012, 12:33

you just have to stick a pen in one ear and pat your tummy while jumping up and down you should know that mictester

deltafred · Post by **deltafred** » 12 Jan 2012, 13:02

mictester wrote:Do these idiots ever actually consider what they're posting? I have seen more stupidity and blinkered bias in a single page of a "hi-fi" forum than I've seen in the whole of FSB!

+1

I couldn't stand reading the drivel on there for long, certain opamps "leaving space around the notes", I soon pressed the back button and found the spec sheet.

A good friend of mine used to waste obscene amounts of money on hifi gear, he still has a very good system but has not updated it for a number of years as his current wife has put a stop to his hifi spending.

He was trying to tell me the other day that my new DIY bass cab would have had a better bass response if it was heavier, and that I did right building the 15" version rather than the 12 as the 12 would not go as low. He wasn't even listening when I was explaining that it was the driver spec and cabinet design that governed the low frequency capability, not mass or speaker size, I think I lost him on mass.

pedalgrinder · Post by **pedalgrinder** » 12 Jan 2012, 13:15

i think your going to have to purchase him a pen to stick in his ear to practice jumping up and down and patting his belly at the same time. Thats how some of these audiophiles get there fantastic results. There are other orifice he could shove it and may even get better results depending how deep it is inserted while the whole jumping up and down process happens.

briggs · Post by **briggs** » 19 Jan 2012, 12:22

ShortScaleMike wrote:Mnay thanks, I can get hold of the NE5534 so I'll give that a shot.

How did the build go Mike? I wanna give this one a try too, I love compressors!

pedalgrinder · Post by **pedalgrinder** » 19 Jan 2012, 15:08

i dare say this one would be cool but as usual lacks a release option on it. But i would also like to know how the build went. Cheers

ShortScaleMike · Post by **ShortScaleMike** » 19 Jan 2012, 16:26

briggs wrote:
ShortScaleMike wrote:Mnay thanks, I can get hold of the NE5534 so I'll give that a shot.
How did the build go Mike? I wanna give this one a try too, I love compressors!

Found some errors in my layout - this should work. It sounds nice.

pedalgrinder · Post by **pedalgrinder** » 19 Jan 2012, 16:36

so your saying this layout is verified yes?????? cheers

ShortScaleMike · Post by **ShortScaleMike** » 19 Jan 2012, 22:39

Yes 0.93 should be all good

pedalgrinder · Post by **pedalgrinder** » 19 Jan 2012, 22:56

is yours working? what is the 0.07? what makes you say that much or where should i be looking cause 0.07 is enough to have dead pedal.

briggs · Post by **briggs** » 20 Jan 2012, 00:55

ShortScaleMike wrote:Yes 0.93 should be all good

I'll grab the schematic tomorrow and have a double check Mike - though it all looks good to me you never know, a fresh pair of eyes and all! How many vero layouts you done now Mike? I've seen a ton from you? You must have a huge collection of DIY pedals!

ShortScaleMike · Post by **ShortScaleMike** » 20 Jan 2012, 08:23

pedalgrinder wrote:is yours working? what is the 0.07? what makes you say that much or where should i be looking cause 0.07 is enough to have dead pedal.

I meant version 0.93 should be fine. See the image, not that it is 7% wrong (seriously, wtf?)

ShortScaleMike · Post by **ShortScaleMike** » 20 Jan 2012, 08:25

briggs wrote:
ShortScaleMike wrote:Yes 0.93 should be all good
I'll grab the schematic tomorrow and have a double check Mike - though it all looks good to me you never know, a fresh pair of eyes and all! How many vero layouts you done now Mike? I've seen a ton from you? You must have a huge collection of DIY pedals!

Thanks, I know I missed off the leading resistor, but I'm not sure what effect that has other than padding down the signal and I don't get distortion.

I've lost count of the layouts I've done, I just started when I started wanting to build pedals really and it got out of hand.

I wish I had a huge collection - half the layouts I've designed I've never built as I did them on the back of requests, and the others were for people ordering them so I don't own them and never did. But if other people can get use out of them too it makes me happy.

I'm not in the league of others though, Ivark, Hbo etc spring to mind.

iltamyrsky · Post by **iltamyrsky** » 21 May 2012, 20:58

Anyone got this working? Mine puts out very loud distorted sound on sustain side of the switch when turn up the compression pot.
On the compression mode it compresses a bit but the compression pot doesn't seem to effect at all, volume and tone are working.
I changed the r10 to 147k instead of 47k based on the schematic and the gutshots on earlier pages, don't know if that did anything to the sound though.
In mikes vero layout stands 34 cuts, I found only 33 in the picture(maybe a typo), verolayout seems to be right as far as I understand it, maybe I've burnt some cap or something.

josepqr · Post by **josepqr** » 31 May 2012, 08:53

Hi all,
took several hours reviewing this circuit, (does not work), and after review and revise the layout, I see several failuresreally .
I'd like to share with you, and give me your opinion.
Following the scheme and interpreting the layout, there are several things to clarify:

'in Really ;;
R17 is R16 really .
R3 is_ R16 really .
D2 is D3 really .
D4, is D3 realy
D1 is D4 really.

(... but this is not too important , typographical errors are only ....)

but if this is important:

Resistance "true" R3 (5K6) is not in the layout, and would have to put it between the C17 and R2.

And finally, all Q2, Q3, Q4 and Q5 are drawn backwards. Because the look and layout must always be interpreted from the top (because that's where the components are stuck).

Took many hours spent on this pedal, still not work for me, and every time I look at meeting some new faultreally .

... I will continue testing.

regards

ShortScaleMike · Post by **ShortScaleMike** » 31 May 2012, 13:55

Looks like I used a standard 2n5088 style CBE top to bottom when straight edge is facing right for transistor orientation. I didn't use BC550cs on mine so I didn't realise they had a reversed pinout.

I built a pedal with this layout. It worked fine.

Maybe design a layout yourself from scratch.

Mad Professor Forest Green Compressor [traced]