Federal Limiter AM864 thread

[Kid Squid]

Dave,
What I was refering to is,

While the unit is 'on' move around wiring (gently ), with a chopstick, or similarly insulated material, and see if this reduces hum in any way (you'd be surprised :wink: )

Worked for me a few times ! :grin:

Steve :thumb:

 

[cannikin]

NO luck with the chopstick

 

[Kid Squid]

Howz the earth continuity around the case, eg front panel to main panel, to earth etc ?

Dave, got me a Federal sitting here with the covers off :grin: , do you want me to take some pics of the wiring layout for you ?

Steve :thumb:

 

[cannikin]

I would love if you could...

I think my PS design is not good

Also how you laid out the rest of the Puppy thanks!

 

[Kid Squid]

I'm on the case Dave,

She's an original, (real nice), But it needs a bit of TLC :grin:

some ' unauthorised ' mods have been done to it, and a friend has asked me to have a look at it for him.

I'll up the pics as soon as they are done.

hope this can help youse :thumb:

 

[cannikin]

Thanks a bunch

 

[Kid Squid]

Hiya Dai,

Took me a while to get the pics on, but here they are :grin:

Full size images are at
http://www.twin-x.com/groupdiy/thumbnails.php?album=75

click on the pics to get the full size pics.

If you need any more, Ill sort 'em out for you, It'll be a few hours, as I got my daughter for a couple of hours . :thumb:

speak to you soon :thumb:

 

[Viitalahde]

[quote author="Kid Squid"]Took me a while to get the pics on, but here they are :grin: [/quote]

NICE! Inspires me in my Analag compressor build.. :thumb:

 

[Kid Squid]

Hiya Jaakko,

Yep, I hope to get one started when , and if , :wink: , Analag lets the cat out of the bag :grin: ....................

:thumb:

 

[cannikin]

What cat is in the bag? :grin: :grin: :grin:

 

[Kid Squid]

:shock:




:wink: :thumb:

 

[cannikin]

do you think a 600:20K input would be OK for the federal or will I be seeing an increase in distortion because of the step-up?

 

[emrr]

that is almost no noticeable step-up amount from the 600:10K; check the math.

 

[cannikin]

thanks Doug -- much appreciated. I didn't think so but wanted to check with the experts.
:sam: :guinness:

 

[emrr]

Cheers!

:guinness: :guinness: :sam: :sam: :guinness: :thumb:

 

[abby normal]

David, here's some more photos for you. This one's all stock. I hope it helps.

 

[tardishead]

anybody finish a clone of this yet??? comments on sound - any modifications.
Can the release time be made faster??

 

[emrr]

you can always make the release faster. You can make it too fast also; then the cap can't ever charge and it never compresses.

 

[Curtis]

I built one a year or so ago. There were some mods I incorporated into the unit as suggested by somebody here, but I can't find the list at the moment. I think all I did was add some extra filtering to the node feeding the wiper of the Current Control pot and used 1N4007 diodes instead of the 5Y3 rectifier. Otherwise the unit was stock. Input/output transformers were Edcor 600:10K. Power transformer was something I had lying around at the time which gave me roughly the right HT supply voltage. I remember I grappled with the unit for a while because of hum problems.

Sounds good on vocals and bass, although the unit has waaaay too much gain for most applications - I can only use it with the input level pot barely off minimum. I think some people here suggested changing the input transformer to 10K:10K for a more usable level, or fitting the output with some kind of pad, but I've yet to try this myself. It's a little bit noisy too, but not enough to worry me in the middle of a full mix.

Just looking at the schematic now, I think making the 1u capacitor (C1) on the cathodes of the 6SK7 smaller will yeild a shorter release time but will also decrease the attack time aswell. Increasing the 47K resistor (R11) feeding the top of the capacitor will compensate to a degree, but there will always be some interaction between attack and release times.

 

[tardishead]

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.

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?

I have not been disappointed so far with anything I have that contains octal tubes. I think I will definitely try building this one.

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.

There is an old AWA limiter with 4 6SK7 and a PP 6SN7 output. That looks cool aswell.