[BUILD] 1176LN Rev D DIY

[Randyman...]

I find I need a "light touch" with my Rev A's.  Even with my input gain around 9 O'Clock, I can still bury the GR needle in certain scenarios - and they can get "farty" in the lows if pushed really hard.  How much GR are you getting with the input driven where it was for that example clip?

The desirable distortion/bite in this box (more the Rev A, but still applies AFAIK) will come from the fast attack/release and make-up gain stage, not from overdriving the input tranny and input stage.  Crank the input down to a sensible GR range, and give the output some more juice.  If you want/need some overdrive then get that from the preamp, not your compressor IMO...

8)

 

[tazman]

The needle was basically buried. Attack and Release at their fastest (I need to check on that, I forgot to write it down).

BTW, where did you attach the ea-5002 transformer ground strands that are soldered to its side?

Thanks,

Rob

 

[Randyman...]

The needle was basically buried. Attack and Release at their fastest (I need to check on that, I forgot to write it down).

Yeah - sounds like gain staging to me.  Back off the input and it should sound fine.  You can usually bury the needle in GR well before you hit the front-end that hard...

BTW, where did you attach the ea-5002 transformer ground strands that are soldered to its side?

Thanks,

Rob

No prob - I ask so much from this place - it's nice to be able to help for a change!  ;D  I put mine on the XLR output Pin 1 - making well sure the entire chassis/EA5002/CM3837/IEC grounds were well-tied and as close to 0 Ohms as possible.  I believe most people chop it off and run the XLR Out Pin 1 to the Star Ground.

Rock on 8)

 

[tazman]

deleted.

 

[Randyman...]

I'm a dummy when it comes to this stuff - but I like to make sure anything that is attached to the chassis is done so with a clean galvanic connection.  My input XLR's have Pin 1 tied to the XLR Screw/nut that attaches them to the chassis - and I made sure there was continuity (0 Ohms) to the XLR shell as well.  Same with the output transformer and output XLR's.  I can measure any piece of metal to any other piece of metal and basically get 0 Ohms - front-panel pots, top plate, side of the chassis, input transformer shell, IEC ground, etc.  She's quiet as can be 

 

[tazman]

Yeah, I agree.  I thought I had a good connection, but I didn't.  I just finished scraping paint off and now I have good ground everywhere...

 

[tazman]

deleted

 

[MPCNYC]

Hi, new to the forum. I'm trying to figure out if the 3708 install in the 3 oval pads provided or the extra circular pad is used. Some, of course just have the 3 oval pads some have the extra round pad.  Checked schematic and forum......still a little confused about this and want to get it right. I have the latest rev d board.

Thanks in advance.

 

[mitsos]

Hey all,

finally getting around to building mine.. I'm using the FET matching jig here:
http://www.nrgrecording.de/html/fetmachting.html

How close do we need to match Ugs? Also, I have a few BF245 and 2N5457 that are close.. Would mixing these between two units be acceptable for "stereo" use?



@MPCNYC, I think the extra pad on some transistors is in case people use alternate transitors (2N5088 I believe). Purple uses those on the MC76/77.

cheers!

 

[blackwaterstudios]

I just finished my 4th rev-d 1176 and fried R32 (39 ohm resistor) and did some reading here and found out I had the output xformer wired wrong.  I corrected that and placed a working unit beside it to double check and I see no other stuff blatantly wrong but I'm still trying to fry R32 when I power on!

Any ideas what I'm missing?  I built 3 more of these just fine and they all work great - stumped on this one...

 

[blackwaterstudios]

No one?  Anyone?

 

[mitsos]

check the rest of the components in the "signal line amp", especially everything around R32. Check the transistors in case any have failed short (you can check with a diode checker function on a DMM, google for instructions).  Check the output trafo in case it was damaged.
good luck

 

[Hank Dussen]

a lot of people had problems with R32.
Search this comlete threat (print version: http://www.groupdiy.com/index.php?action=printpage;topic=20058.0)

 

[baadc0de]

Hi,

my rev d passes signal, seems to compress alright, all the controls are cool, except for the meter in GR mode that just sits at -infinity and doesn't budge. Probably a wiring error? The meter works cool at +4. It's a rotary version. I have successfully adjusted the q bias, but not the meter because neither the 0 set and zero adjust move the needle from -inf.

Also, because I couldn't get the correct rotary switch for the ratio board and the replacement I got didn't work with my front panel, I decided to use a simple lorlin 2x6 limited to 2x4 and add a DPDT switch to do the "ALL" mode. Basically I just connect both the poles of the rotary switch and connect the DPDT so that when slam is "enabled" it also "pushes in" the 4:1 button? so when the rotary is on 20:1 and I engage the "slam enable" DPDT, it will be like if you pressed 20:1 and 4:1 at the same time.

 

[tazman]

I did some more testing with my Rev D.  I get noticeable distortion if I have the Release set to fast and especially if the attack is set to slow.  Otherwise it seems ok.  Where should I start looking for the problem?

Thanks,

 

[baadc0de]

My error for GR not working were swapped meter wires

can aynone comment on the slam dpdt?

Also, I can't do the meter calibration #3, with the tracking adjust trimmer in, I can't get the -10dB point in GR mode, because the trimmer's range is too small (or so it seems) so it shows more like -14dB. Could I install a larger trimmer?

For the distortion trim, I have another PCB that I don't seem to have a trimmer for, could I just use two 50ohm resistors and wire them up temporarily instead of the trimmer, so, two resistors meet on the "wiper" and one goes to ccw, other cw holes.

Thanks,B.

 

[tazman]

Here are samples of the distortion:

Attack Slow, Release Slow, Input to get -20 db compression (basically over compressed, but needle is not buried, it moves a bit).

http://www.robertocerini.com/test1176-slow%20slow%20-20.mp3


Here's one with slow attack, fast release and inout set for the needle to dance around with a max compression of -10db.


http://www.robertocerini.com/test1176-slow%20Fast%20-10-Audio%201.mp3


Any thoughts or suggestions?

Thanks,

Rob

 

[MicDaddy]

tazman links are not working

 

[tazman]

Fixed the links.  Sorry

 

[tazman]

Deleted.