All things G1176 - the new "repost" thread.

http://twin-x.com/groupdiy/displayimage.php?pos=-3537

FPE file

Untested, Meters are Sifam Retro Al-15 with 2-56 screws to front panel.
Tried to stuff it all in a Par-metal case, you will need to nibble the front lips in places to allow the pots and switches room to breath.

Please verify before use.

Note:
no Power Switch
Stereo link switch is provided.
You will also need to make provision for the Meter PCB as it's changed to a toggle switch
mounting of  the Ratio pcb off the switch or use a Alapha switch for All(nuke) mode.
This is semi modeled after Mnats killer 1U dual build.

Kaz

it Looks nice Kaz,
unfortunatly I can't open the link you provided.

sorry, it was late and is fixed now.

FET Question. I have the Rev J board from mnats. The FET's used are the BF245A. I just received some 2N5457 FET's from Hairball. Do the 2N5457's go in flipped around? It looks like the pins between the two FET's are opposite each other. Please correct me if Im wrong.

That's correct. The 2N5457 FET is the opposite way around from the BF245A FET.

In order to permanently enable the GR, can you simply tie pad 22 and the GRN pad on the ratio board together?

Ptownkid said:

In order to permanently enable the GR, can you simply tie pad 22 and the GRN pad on the ratio board together?

Click to expand...

Yes sir-eeeeee. May I ask why you would want to do that? Just curious.

Best,
Brandon

Hello everyone,

I'm haveing a little troubble with my rev J   in GR mode the meter reads - 1.5 db and doesn't change,
there is no gain reduction going on,
Also the spot marked -10 V I'm getting -7.33 V  on the one side of R85  and the other side I'm getting -14V
my +30 V is ok,

Mike

Does anyone have an .fpd file for the push button faceplate?
Cheers

I have one but I can't figure out how to post it to my webpage.  If I do, and you click it, it shows as a bunch of characters.

You can email me for the file.

info (at) hairballaudio (dot) com

Does anyone have the original UREI scale for the Sifam Level Meter?

Hello All,

My dual build is close to completion now. I have managed to iron out a number of issues and have both channels compressing, and passing audio adequately. Unfortunately though I cant complete the calibration procedure yet, as I am having problems with the VU metering.

When applying the 0.775mv 1k tone, in GR mode the needle responds to the 205mv provided and it sits up aroun+1, but in VU mode it is dead. Points x and y on the main board measure 0mv when input and output are turned down and measure -0.05mv when both turned up fully clockwise.

What am i missing here?

How does the meter measure the output when it is accross x and y and not referenced to ground?

Mac.

Also, a couple of additional comments.

I found that the meter was almost reading nothing at all unless I started by turning the zero adjust trimmer right up till the needle was roughly at zero when you switch GR metering on.

I have used Spectrol multi turn trimmers in all these positions.

Rechecked and double checked wiring - still no good (both channels operating identically).

Mac.

Mac,

..as mentioned several times before in this thread, you need a "real" i.e. AC-reading vu-meter for the G1176..

Jakob E.

So your unit is passing audio but not showing any voltage on the X and Y pads? The X and Y pads are directly connected to the output transformer, so unless these traces are cut there really couldn't be any audio passing. Also the meter measures the output with no ground because audio is AC. In GR mode there is no audio passing just the differences in voltage due to compression taking place. Also in GR mode your meter should read Zero. You have me stumped ??? I hope you get it figured out, but as I understand it if there is nothing on the X and Y pads there is nothing coming out of the output transformer.

Brandon

Yeah thanks guys...I am using these meters from JLM http://www.jlmaudio.com/shop/index.php?_a=viewProd&productId=20  which i understood to be "real" vu meters.

I shall ring Joe tomorrow and see if I stuffed up on this point - before going further. Maybe I can salvage my design (my whole layout is hinged on these meters now..) , and still use these meters with two of Joes VU rectifier kits.


cheers, Mac.

Or you can just buy some germanium or schottky rectifiers and wire them to the terminals as a bridge. It's easy to do.

Yes, that would be easier....I need to walk away for a bit.....have been at it for the last two days ......not thinking straight now.

Geoff, would these be OK, (only because they are the closest thing Jaycar have -avoids postage) ...  1N5819 1A 600mV Schottky Diode

http://www.jaycar.com.au/products_uploaded/ZR1020.pdf

mac

Better stiill, try ZR1141 (BAT46/48) which is a small signal shottky that will do the trick.

OK Geoff, so with these do you suggest a four diode bridge, and i suppose you would need a series resistor also?

I have seen some circuits around the traps but most of them seem to needlessly complicate matters.

Mac