Federal Limiter AM864 thread

[Curtis]

Thanks for that. You dont seem that enamoured with your unit.
Get yourself a Daven for the unit - it definitely will help you using it.
I have them on almost all my tube stuff.
You are probably not really driivng the unit for much compression having the input down so low. With a pad you can really drive the input and hear more of the character of the unit.

Hehe, sorry if I came across a bit down on the unit, certainly wasn't intended. Must've just had a case of Monday-itis :razz: On the contrary, I quite like the unit despite it's foibles. It's pretty much permanently patched into one channel of my G9 for bass DI duties when laying down demos and such.

Surely the 1uf cap can be kept and the 2M resistor can be made smaller to make the release time shorter? Or am I missing something?

Making the 2 meg resistor too small will mess with the biasing and gain control of the input stage. It needs to be large to prevent loading the sidechain with the input stage. Experiment and see what you can get away with.

Did you end up winding the heaters with a balanced configuration / centre tap to ground like most other units? There seems no reason why it should be wired unbalanced.

I think the power transformer I used had a centre-tapped heater winding (3.15-0-3.15), so I just earthed the centre tap. Although from memory I don't think it made much difference to the hum level if I ran the CT earthed or not.

 

[tardishead]

what kind of chassis did you use for the unit. I was thinking of trying to squeeze everything into a 2u rack chassis - unless you can think of a major issue with that.
cheers

 

[Curtis]

Rolled my own 2u chassis - had a bit of 1.5mm Aluminium sheet and a 2u blanking panel lying around and just bent, pop-rivetted and screwed it all together. Pretty shallow case, about 120mm deep, but it all fits inside nicely. Power transformer and valves poke out the back, input/ouput transformers mounted inside. If I get a chance I can take some photos if you like?

 

[tardishead]

that would be helpful.
Yeh I think I will build mine in a 2u chassis 110mm deep.

 

[inputoutput]

Here's my original AM684. Drilled a few holes, and moved the controls to the front, but haven't done any modding. No need...,it sounds fantastic as it is! I often sneak it in in the center of the mix, in the middle, --after I'm done mixing the overall levels.

I got the rotary number-plates from Farnell. Just glued them on. The unit doesn't seem to get especially hot, so a 2U box will probably work fine.

Let me know if anyone needs some info, and I'll see what I can find out.

 

[Curtis]

Happy snaps:

...and a few more here:

http://i153.photobucket.com/albums/s222/ac1176/P9030219.jpg
http://i153.photobucket.com/albums/s222/ac1176/P9030220.jpg
http://i153.photobucket.com/albums/s222/ac1176/P9030221.jpg
http://i153.photobucket.com/albums/s222/ac1176/P9030222.jpg

 

[inputoutput]

looks good! and "HARDNESS" sounds like an appropriate name for the pot! :thumb:

 

[Kamel]

Hi all, maybe someone can give me specifications of the vu meter, there is no value in the manual

 

[cannikin]

I believe the VU is 1fs... but can't remember... I'll look when I get home

Its posted somewhere in this thread.

Here my units:

 

[Kamel]

thank you, your clones had beautifull look

 

[tardishead]

Cannikin those chassis are great where did you get them from???

 

[Viitalahde]

[quote author="cannikin"]

[/quote]

So sweet.. :thumb:

 

[tardishead]

Also those jewel/bezel yellow things. They are sick.

 

[cannikin]

thanks guys...

they are series 14 chassis from Par Metal
part number: 14-19062A
lamps jewels are these NOS, I picked up a while ago.

the meters are original

 

[user 10827]

Hi all,

EDIT
I just fired up my FED!!

its working! but loads of clipping and distortion, need to work ut what part of the circuit is distorting.

if i was to pad the input, could i change the circuit to lower the threshold??

my worry is if i lower the input to much it will fall out of range of the compressor..

any advice would be welcome.

best

pete

 

[user 10827]

here they are...

I had to load the output with a 600ohm resister, change R3 & R4 to 12K from 47K, also added a switch to half the release time.

there is a little hum on the release of compression, can live with that.

really enjoyed the build, great unique piece of gear, loving it!

thanks to kidsquid who had the mains transformers made. :guinness:


http://www.sinestarproject.com/fed1

http://www.sinestarproject.com/fed2

http://www.sinestarproject.com/fed3

 

[cannikin]

Wow really nice work!!!!!!!!!!!

where did you get those plates made like the original... that say federal Am?

 

[user 10827]

thanks you sir!

yes i made the panels my self, and the labels,

here you are, i made a quick PDF for any one that wants it..

http://www.sinestarproject.com/fedplate


Ill have to check but I think I have two sticky labels left if any one wants them..

cheers

Pete

 

[cannikin]

Awesome thanks So Much... really I love your build better than mine.
What transformers did you use

 

[user 10827]

don't be silly, you're a legend round these parts! your stuff is way cooler..id like to try your 1954 some day..

i just copy the original designs, were is the creativity in that! but i do get a kick of doing that..bit like a counterfeiter!!

transformers i used Edcors 600/10k and 10k/600, sounds really quite good, im quite surprised.

there is some low end boost, every thing sounds really warm and fat through it...not sure it that is normal? and a small little hum only when it is releasing from compression...but its not there at idle.. its fine as its subtle but i would like to know what is is..

pete