Federal AM864/u mods and MAXSON Dept. of commerce

I have two Federal AM864/u limiters in near mint condition. Does anyone else here have one these units? These are great and have the original tubes; these look like they virtually came right out of the box.

I have a manual for them and I was thinking about possible mods (output control, attack and release). Has anyone modded these?

I have MAXSON Dept. of commerce too nad I understand that it can be modded to open up the bandwitdh etc... Does anyone have any thought's on this unit?

The schematic is here AM-864
Nice simple design.
A friend says it is a very colored design though.
I measured one real quick for a friend I think the transformers may limit
the sonics.

Let the group digest this and I know they will have some mods.

They made two versions. One version was bandwidth for speech like 300hz to 10khz or so. The other was full range. 30 or 40 hz to 15 khz.

I had the speech model. It was great for guitars but required some major shelving after it.

I love the way they sound, Killer for Bass and Vocals sound real cool through it. I don't think these are the speech versions. They sound fat!!!

The Maxson is more limited in freq range and most likely needs some mods to widen it to be more useful.

Michale Brauer used the Maxson on Aimee Mann's vocals for her Lost in Space album, it's a real signature; his was modded range wise.

The Federal's are the "Magic Box" as my buddy says. We recorded a Modulus 6 string bass through it and then into a silver faced 1176 to a RADAR; It was outstanding.

If the DIY group comes up with anything, that would be great.

Bump:

Anyone come up with anything on the Maxson?

Hey
I jusy got a good copy of the Federal complete manual 40 pages or so.
I will get it scanned and hosted somewhere in the next several weeks!

Cool, I have the manual too; no scanner though.

Well well then.
Why did I just spend my hard earned money on the manual?.........
because I thought you guys here did not have one.

Bummer

OK OK in the DIY spirit all is well.

Will have it done soon.

We have a networked digital copier at work.
8 seconds per page right into my graphics program.
Thank you Mr TWAIN
De-spot the image and rotate
and converet to PDF it is getting better all the time!

Sorry dude, In my original post I wrote the I had a manual. I wanted to know if anyone had modded them in any way or had experience with them.

I love my units, however the MAXSON ca1589 is the one that really needs to have it freq range widened to be more useful for other things.

The Federal AM 864/U is unreal on Bass and Vocals.

Hiya Tubemonkey for what it might be worth iv just DIYed myself a AM864 from bits & bobs I had laying about as bit of an experiment really, spent no money I borrowed the input & output trans from a recently finnished DIY BA6A, they are Sowter transformers 1:4 in & 9:1 OP I think I have no idea what the real AM864s have in them but this thing sounds fantastic on vocals to my humble ears, its as useful as my BA6A,it just seems to make the voice just sit right in the mix, im so glad I did the experiment

Try it on Bass gtr

Hey ,
I need the am864 manual.
did it get scanned and converted to pdf?
please post or e-mail it to me
thanks
ts

I would love to have a copy also...

I think adrianh made a copy.

OK I am slow.

But I am still working on it, all 66 pages.

I will get it done. Yes everyone can have a copy, when I am done.

I will kick myself and see if it gets done faster.

much thanks
ts

bumping this thread here

IS there a manual anywhere (yet!!)

cheers for ALL the great info on this board!

I would like you to think about the way of connecting this compressor for stereo operation. I'm looking at the circuit and seems pretty interesting. I think it will fit great for mastering.
I've read a lot of about this compressor but nobody says much about the way it sounds/ works.
Thanks.

There's another Maxson thread somewhere.   

The Maxson with Langevin transformers is one of those pieces where the freq printed on most of the iron is accurate (300-5K?).  The repeat coil on the output is the only one that is flat on the bottom.  The input and output do not do low end.  Or high end, for that matter.    The input could be replaced, the output is specialized and really can't be.    You will get some more lows raising the value of the coupling caps, but I was not able to go far before it turned into a motorboating bitch, and raising filter cap values/adding more filter stages didn't help.    A tailored feedback mod could counteract the roll-off in the iron; haven't tried it.  Would have to knock the overall gain down quite a bit too.  I imagine with the phase displacements of the iron that you would run into positive feedback instability if a tailored feedback network went very far at all.  I could be wrong on that.

It is a voice freq piece; best celebrated as such.  Easier and cheaper to build something else.  Replacing anything in it would make it not be the special effects box it is, so there's not much point, IMO.   It might have when they were $300 or less, but not anymore.