Federal Limiter AM864 thread

[tk@halmi]

I would love to use one of these:
http://www.leedselect.com/images-meters/Weston3532.JPG
At $125 a piece it will just not happen. :sad:

I have one of these Calrad's left over from other projects. They are not vintage looking, but work well and cost less than twenty bucks:
http://electronicpartsdirect.com/nexternal_categories.cfm?category=147

 

[NewYorkDave]

The Calrad has an internal series resistor and rectifier. But if needed, it's easy enough to remove them for external use.

More info on Calrad 60-148, from measurements I made in April of '04.

http://electronicdave.myhosting.net/miscimages/calrad.gif

As with any rectifier-type meter, the impedance varies with level. Here's some impedance data that's a little more specific than what's on the drawing:

9.4k at -2dBM
6.2k at +4dBM
4.9k at +14dBM
Measured at 10Hz, 100Hz, 1kHz, 10kHz and 100kHz. Impedance falls
slightly at 100kHz. In light of these numbers, the figure given on the drawing must have been made at a rather low level, but I didn't note it at the time.

These figures include the internal rectifier and series resistor.

 

[bradb]

Has anyone out there put a pad on their input or output or both?


I was thinking of padding the input and output 10dB or padding just the input 20dB, mine are very hot. any recommondations or experiences?

thanks!

 

[kvintus]

Does Edcor have transformers suitable for input/output also? Would be great to get all the transformers from one place and cheaper than sowter.

/Anders

 

[bradb]

I put a 20dB 600Ohm pad in over the weekend on one of my federals, it really sounds bad.. i did the 240Ohm and 121 Ohm H-bridge (if i remember those numbers correctly)

has anyone gotten these to be less... hot?

 

[kvintus]

I was thinking about something like

XSM600/10K Matching Xformer
XSM10K/600 Matching Xformer

Or should I look for something else?


/Anders

 

[tk@halmi]

Well, depending on your requirements, the Edcor's may work. When I have all the parts I intend to try the WSM600/10k and the WSM10k/10k for the input and the XSM10k/600 for the output. I am concerned that the Edcor input transformer is not shielded, but I have no experience or expertise to say if it will have interference problems once everything is tucked away in a metal case.
NewYorkDave seem to have had good success with Edcors as ground loop isolators, and he posted about his projects a couple of weeks back. Perhaps Dave can advise on the possible success of using the WSM600/10k for a differential input in this circuit.

I am working with Edcor to trial a 15k/600 (for Altec 436C) and a 10k/600 transformer for the AM864 that use larger cores for full 1W output and to absorb a bit more current than the XSM series. The cost should be around $20. Results may be several weeks out as these will be custom winds on custom cores.

Cheers,
Tamas

 

[bradb]

Interesting ideas guys, it would be nice to see if you could "open" up the federal sound with a different input tranny.

edcor is the best...really. I wonder if they know about this forum?

 

[kvintus]

That's great, Tamas!

Keep us informed!

/Anders

 

[audioforge]

bradb
for a 25db pad before the input transformer you can try:
270R ----- 270R
!
68R
!
270R -------270R


audioforge

 

[audioforge]

grrrr.... bad editing. the 68 r is between the 2 270r upside and the 2 270r downside. H.

 

[Guest]

I have a few Federal questions.

1. What is the approximate range of the threshold control?
2. what does the "current control" pot do?
3 Is there a reason you wouldn't want these pots on the front panel if you are going to build one from scratch?

Thanks,

elco

 

[kvintus]

I think there was some talk about the controls in an other thread somewhere, but I can't find it now. Anyone?

Here's an other question for you:

I would like you to think about the way of connecting this compressor for stereo operation

Was this question ever answered? Supermagoo has asked it in at least 4 different threads but I can't find any answer. And the more I think about it, the more I want to know. So, can this compressor be linked for stereo?

/Anders

 

[tk@halmi]

Hey, I got the Edcor power transformers today!
This is the label on the box:
http://mysite.verizon.net/res75okq/sitebuildercontent/sitebuilderfiles/xpwr012_boxlabel.jpg
This is a picture of the front:
http://mysite.verizon.net/res75okq/sitebuildercontent/sitebuilderfiles/xpwr012_front.jpg
This is the bottom with the label:
http://mysite.verizon.net/res75okq/sitebuildercontent/sitebuilderfiles/xpwr012_bottom.jpg
A mistery picture. The hairy, fat, short dude is me, no mistery there. The question to USA DIY-ers: what is the signficance of the house and where is it?
(The picture of Paul Revere's house that used to be here has been removed to make room for other files on my website.)

I measured the following voltages UNLOADED:
5V tap: 5.38V
6.3V tap: 6.73V
350V tap: 378V

No time for anything else unfortunately. Starting tomorrow, I will be on vacation for the next week traveling up and down the west coast. :grin:

Cheers,
Tamas

 

[PRR]

> what is the signficance of the house and where is it?

Why don't you leave bigger clues?

That vehicle has a legible phone number. Stick that at Google, you must be near Maurizio's, 364 Hanover St, Boston, MA 02113, 617-367-1123. However a Google or Virtual Earth map showed that Maurizio's is not in a building like that. Of course of all the things that happened in Boston, one stands out. And it is just up the street from Maurizio's. http://www.paulreverehouse.org/ As you see from that picture, they closed the shutters when they saw you coming. "Tamas is coming! Tamas is coming! One LED if by car, two LEDs if by subway! Lock the gift shoppe!"

 

[CJ]

Wow!
Move over, Sherlock!

 

[jrd]

which reminds me that i must go to mikes asap. mmmm. hopefully somebody knows what i'm talking about.....

 

[tubemonkey35]

Think of the Threshold as RATIO and Current as Threshhold.
When I read the manual it was the first thing I noticed.

 

[audioforge]

hi Tubemonkey35
could it be possible you write what you think the most important things in the manual (such tubes voltages (or confirm the ones soundguy gave in his federal thread) voltage on r8 pot, meter adjustement procedure, general adjustement .... as i don t think we see one day the complete pdf manual....
this would be nice but i will understand you l find it too much boring...
and you have been yet very helpfull for this federal clone thread.
audioforge
btw a peacefull new year for all of you lab guys

 

[Svart]

why do you guys insist on doing this to me??? everytime i think I might have a handle on all my DIY you come up with another that i MUST do.. :evil: