Official Forssell Limiter Build thread

[hitchhiker]

hey Dave,

This is the original PDF schem that Fred had on his site.

http://www.forsselltech.com/SideChain.PDF

It shows a VU meter hook up. I use this on my proto and it works very well.

note: The opto is tied to grnd not + voltage.

cheers,
Lance

 

[tommytones]

C32 + C33 are not needed for the discrete input.

C29 + C30 are just that. C27 + C28 are lytics. Look at the parts list, it's all there.

As for the analog meter, if you browse through the big thread there was mention of how to get one to work. If you choose the LED path, then you have several options. You can go with individual LED's and position as you would or you can get some 10 segment arrays. Digikey has.

I hadn't noticed there wasn't any make up pot for the front panel. You'll have to add one (unless Frank catches on and updates his file). This layout is a starting point as I see it. Mod to taste.

Quick note about the make-up. For the dicrete output, there never really was any pot since I don't think the circuit was meant to be used in this area (I may be wrong). I figure that plcing a pot in the feed back (a la API gain) will do the job nicely. For the 5534 output, butta implemented the make-up pot into his circuit (RV1 on the schem and pcb).

 

[j.hall]

does the discrete output track with the gain reduction then?

i had some dbx 164's that did that.

if i smash something really hard (like 10db of GR) i want to make sure i get that 10db back on the output side. and i really want to go discrete.

 

[Bear]

Cool, I was about to ask about VU metering. The VU should make it sound warmer and everything. :wink:

Bear

 

[hitchhiker]

I noticed instant warmth and depth whith a VU. :sam:

 

[Helsing]

I drew up a schematic of what I "think" fred described as a simple way to do analog metering.

I dont have a way to post images. Perhaps someone could post it for me?

PM me.

Helsing

 

[Kev]

send to me

give me whatever you want to appear with the picture like your name and contacts and such

I'll add it to the DIY Factory page ... FFOSC

 

[Kev]

no time right now
I'll try to do better tomorrow

in the mean time here is a smaller version of Helsing's drawing.

http://www.diyfactory.com/projects/forsselllimiter/helsing_vu.jpg

 

[strangeandbouncy]

hi all,

is there any reason why i can't wire a Forssell 992 in place of a 5534 in butta's output stage, which has gain make-up?

ho hum . . . .

AndyP

 

[dramadisease]

that metering is interesting! i have a bunch of mA meters... would that diagram work into most compression circuits? i dont know a whole lot about gain reduction metering, but i find myself using it alot when i use plugin compressors.

thanks
-bryan

 

[Infernal_Death]

Since it seems that Alphastat is out of 5k neg log potis right now, Frank and I are thinking about a replacement.
So right now is it possible to buy a stereo 10k neg log poti and connect both "decks" in parallel with each other ? It should work in theory, well if i haven't missed anything (which could be very well).

Also maybe i am blind but i wasn't able to source the informations about the C43 cap on the board. Not in the parts lists (rev1 and rev2) nor in any of the schematics. Anybody know the values ?

Flo

 

[j.hall]

as posted by tk@halmi:

I have posted about three times that Newark carries them (search for "T13") for about six months. They had 372 pieces last week still and now they are all gone. If you buy some dual 10k revlogs from Joe Malone you can wire them in parallel to get 5K.

Tamas

go for it. i'll probably do the same unless some 5k rev. log pots pop up prior to me starting this project.

 

[tommytones]

C43 is electrolytic 33uF/35V or similar. It's just a small stabilizer for the +24V to the meter. I'll add it to the parts list rev3.

 

[Svart]

is there a link to the full schematic? I don't see on fred's schematic where the 2n(pn)5457 is located.. I just need to know if i can sub this with something like a 2n4392..

 

[tommytones]

Here

There you'll find all the schems and so on. The transistor is not for any of Fred's circuits though. It's for use with the 5534 output driver. Be sure to look over all the doc's before you begin stuffing. I wouldn't want anyone to have any unfortunate accidents.

 

[Svart]

ok thanks tommy!

 

[babyhead]

This kind of OT, but am I right that could make a 5k 10k or 20k rev log pot from a dual 10k RL. If this is so, the JLM pot would fit most of my Rev Log needs... :guinness:

Looking at the schematic, if we reversed a 5k audio pot for the ratio, would we end up with 1:1 on the right side? I could live with that cuz I have a line on ganged (6 elements!) Vimex 5k audio pots...

 

[tommytones]

Yup...

 

[tommytones]

Okay...I'm upset now :evil: Someone has succesfully emptied out Newark of all the 5k rev logs and 500k lin pots I was gonna use for my units! There's like a 60 day wait until they restock the 5k rev logs and 160 for the 500k's :twisted:

Luckily, I was able to find everything but the rev log (I got log for now until I can get the correct pot from Newark) at Allied for roughly the same cost.

 

[j.hall]

do you mind sharing those part numbers from newark, i'm assembling a pretty nice parts list, and i'm in no hurry for parts at this point....

thanks in advance.