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1176 Slow Attack Mod Dynamics Processors (HW)
Old 7th August 2014
  #1
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1176 Slow Attack Mod

1176 too fast? Want a full 10ms attack time? Here's how....

Essentially you add a switch paralleled with a 220k resistor (metal film type preferably) in series with the clockwise lug of the attack knob. When the switch is closed, the unit will behave completely normally. When the switch is opened the attack time will go to about 10ms and the attack knob will have little/no effect. Disconnect the CLOCKWISE lug of the attack knob from whatever wires/pcb connection it has. Connect as per the schematic below. It's possible to reconfigure the "Gain reduction off" switch in the pot to do this (like the 1176 A/E), I may post some hints on how to do this if people ask.

This mod is applicable to 1176 revision D and although I haven't tested, should be applicable to other revisions, especially A and F. I should also mention I did this on a MNATS type clone, although I don't see why you couldn't do this to a stock unit.

If you don't know what you are doing with a soldering iron and don't have a modest understanding of what resistors are and whatnot, don't try this. This isn't a difficult mod, but please don't ruin your 1176.

Attached is the schematic:
Attached Thumbnails
1176 Slow Attack Mod-1176-slow-schematic.jpg  
Old 7th August 2014
  #2
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Here's some waveforms of the mod in action. I just had a sine wave jump up in volume for a period of time and recorded the results in cubase.

Track 1: No gain reduction (compressor off)
Track 2: Normal mode, attack all the way right (fast)
Track 3: Normal mode, attack all the way left (slow)
Track 4: Slow attack mode

Release is set all the way fast in all four.

It's interesting to note the slower attack slightly changes the threshold, so the audio is a bit less compressed with the slow attack enabled. Maybe I'll look at adding a threshold adjustment to this switch as well.
Attached Thumbnails
1176 Slow Attack Mod-1176-time-constants.jpg   1176 Slow Attack Mod-1176-time-constants-zoom.jpg  

Last edited by FearLabs; 7th August 2014 at 10:42 AM.. Reason: Correction
Old 7th August 2014
  #3
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Drumsound's Avatar
Isn't the whole point of an 1176 is that its fast and grabby?
Old 8th August 2014
  #4
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Quote:
Originally Posted by Drumsound View Post
Isn't the whole point of an 1176 is that its fast and grabby?
For some, sure! It does that well. It also has other positive attributes to it's sound that have nothing to do with that. The distressor is basically a heavily modified 1176-style fet compressor with more versatility (like long attack times amongst other things). Having an extra thing you can do with your nice tools can't be a bad thing. If you never want a slower attack time than what it comes with stock, then by all means don't do this. It's not for you, obviously.

Also I should say this is an attempt to do part of what UA did with a special release of the 1176, the 1176 A/E. That unit was a hybrid of the rev. A and the low noise circuits of the rev. E. Also had 2:1 ratio, and a 10ms attack mod.

Last edited by FearLabs; 8th August 2014 at 12:53 AM.. Reason: more info
Old 8th August 2014
  #5
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After playing with this new sound, I should mention that since the attack is slower and the threshold is slightly raised, you will need to push the input harder to get more compression. When you do this it's easy to get overdriving internally. Not gonna hurt anything, but it's tough to get a super slammed sound with a slow attack without trashing it up a bit.

To address this I am looking into an addition to this mod that lowers the threshold to allow for more punishing and pounding if you so desire. I'll post something here in the next week or two once I find the time.

With gentler, more sane compression this mod works with no issues.

Last edited by FearLabs; 8th August 2014 at 12:43 AM.. Reason: grammar
Old 8th August 2014
  #6
I've always wanted one with a slow attack. There is much more to an 1176 than its speed IMHO. Although 30ms would be better so I could use a pair on two bus.
Old 8th August 2014
  #7
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Red Black's Avatar
Quote:
Originally Posted by FearLabs View Post
After playing with this new sound, I should mention that since the attack is slower and the threshold is slightly raised, you will need to push the input harder to get more compression. When you do this it's easy to get overdriving internally. Not gonna hurt anything, but it's tough to get a super slammed sound with a slow attack without trashing it up a bit.

To address this I am looking into an addition to this mod that lowers the threshold to allow for more punishing and pounding if you so desire. I'll post something here in the next week or two once I find the time.

With gentler, more sane compression this mod works with no issues.
Fantastic! This thread is awesome...
Old 1st March 2016
  #8
Great thread, thank you!

looking at your schematic, it seems that this will also affect the release time, am I correct?

Is the threshold affected because the Q Bias point (R59) is also wired in series in this part of the circuit?
Old 2nd March 2016
  #9
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Why not just replace the 25K attack potentiometer with a 100K or even 250K, giving you a much larger usable range without affecting the fastest times?

Jakob E.
Old 2nd March 2016
  #10
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lordward's Avatar
Quote:
Originally Posted by gyraf View Post
Why not just replace the 25K attack potentiometer with a 100K or even 250K, giving you a much larger usable range without affecting the fastest times?

Jakob E.
That's what I was thinking.
Old 20th April 2016
  #11
Quote:
Originally Posted by FearLabs View Post

It's possible to reconfigure the "Gain reduction off" switch in the pot to do this (like the 1176 A/E), I may post some hints on how to do this if people ask.

Attached is the schematic:
that would be great! cheers
Old 23rd April 2016
  #12
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Quote:
Originally Posted by gyraf View Post
Why not just replace the 25K attack potentiometer with a 100K or even 250K, giving you a much larger usable range without affecting the fastest times?

Jakob E.
I agree. I've done this for customers. Way easier than adding a switch to the front panel and you don't lose your fastest attack times. If you add a toggle switch, that hole in the front panel is there forever. Swapping out the pot allows the mod to be reversible if you ever want to go back to stock.
Old 26th April 2016
  #13
Quote:
Originally Posted by mexicola View Post
I agree. I've done this for customers. Way easier than adding a switch to the front panel and you don't lose your fastest attack times. If you add a toggle switch, that hole in the front panel is there forever. Swapping out the pot allows the mod to be reversible if you ever want to go back to stock.

I think i'll do this aswell, If the poti has a spdt switch incorporated then the GR OFF function should still be working aswell right?
Old 26th April 2016
  #14
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Quote:
Originally Posted by juleselipse View Post
I think i'll do this aswell, If the poti has a spdt switch incorporated then the GR OFF function should still be working aswell right?
Yeah. I can't remember the part number, but Alpha should make one with an SPDT switch that's 100k ohms. Not sure if they make one that's 250k or not. I know the 25k ohms one that Hairball sells is made by Alpha. You should be able to find it with some searching on Mouser.
Old 27th April 2016
  #15
Quote:
Originally Posted by mexicola View Post
If you add a toggle switch, that hole in the front panel is there forever. Swapping out the pot allows the mod to be reversible if you ever want to go back to stock.

I'm doing a whole on the front panel though, but for side chain purposes.

see here: 1176 Rev A - external sidechain using a DPDT Switch

instead of wiring the ccw lug straight to the ratio board I insert a DPDT switch allowing me to choose between internal and external side chain. I'm just not sure if I should process the external side chain signal before it reaches the switch (run it through a filter first)
Old 27th April 2016
  #16
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Without seeing a schematic of what you're doing, I can't really answer your question. I'm not really clear on what you mean by "process the external signal before it reaches the switch".

But take a look at this, schematics on the last two pages. Specifically the "insert loop drive" and "insert loop return". Note their location in the circuit, as well as the driver and return amps themselves. It should give you some ideas.

http://www.purpleaudio.com/product/PurpleMC77v34.pdf
Old 27th April 2016
  #17
Quote:
Originally Posted by mexicola View Post
Without seeing a schematic of what you're doing, I can't really answer your question. I'm not really clear on what you mean by "process the external signal before it reaches the switch".

But take a look at this, schematics on the last two pages. Specifically the "insert loop drive" and "insert loop return". Note their location in the circuit, as well as the driver and return amps themselves. It should give you some ideas.

http://www.purpleaudio.com/product/PurpleMC77v34.pdf
Yes, the MC76 insert loop drive was the basis of my build basically.

imagine a DPDT switch between point 15 and R78 on this schematic: that's what I'm doing. http://mnats.net/files/1176REVA_125_VOLTAGES.pdf

pole 1 dpdt: point 15 from output CCW lug
pole 2 dpdt: Hot wire from external side chain XLR
Throw 1 dpdt: to R78

I'm just thinking about adding a HPF before the switch on the external side chain path in order to have a bit more precise compression.
Old 25th May 2016
  #18
Why Would the GR OFF function not work when adding the resistor in // ? It should work normally right?
Old 25th May 2016
  #19
I'm thinking of adding one of these instead of the resistor in parallel:

http://www.tme.eu/de/Document/953303...78904/3310.pdf

this way I can still have a fully normal attack time, and control the attack time when in slow mode.

What do you think?
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