Harpo

Re: The best noise gate?
« Reply #20 on: December 28, 2018, 12:09:57 PM »
That's for a 202 - what is the difference from 201?

Jakob E.
DS201 schematic attached...
A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.  -Douglas Adams


abbey road d enfer

Re: The best noise gate?
« Reply #21 on: December 29, 2018, 04:54:40 AM »
from the base of the first 2N3704 down to gnd?
That one is probably AOT; it must be so that the FET is off without signal.

Quote
and after the third 3704 connecting to the release pot?
According to specs, the relase time is adjustable from 30ms to 5s. 2Megohms for 5s imply 12kohm for 30ms. There is already about 2 kohm (10k//2.7k) at the foot of the pot. I would vouch for 10k.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

abbey road d enfer

Re: The best noise gate?
« Reply #22 on: December 29, 2018, 05:04:20 AM »
Anyone have any thoughts on this and a schematic for the kepex?
http://www.analogrules.com/manuals/outboard1.html
That's the complete files with all versions (neon and LED meter)
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

Spencerleehorton

Re: The best noise gate?
« Reply #23 on: December 29, 2018, 08:34:03 AM »
Ah ok, so the second resistor i'll try a 10k, thanks, don't understand the AOT for the first one sorry? not good with acronyms!!!!
website: www.mohawkstudios.co.uk
email: [email protected]

If it hisses its probably the wrong impedance!!!

Rob Flinn

Re: The best noise gate?
« Reply #24 on: December 29, 2018, 09:06:37 AM »
Ah ok, so the second resistor i'll try a 10k, thanks, don't understand the AOT for the first one sorry? not good with acronyms!!!!

AOT = Adjust On Test.  i.e probably selected for the particular unit.
regards Rob

Spencerleehorton

Re: The best noise gate?
« Reply #25 on: December 29, 2018, 10:30:18 AM »
ah ok, i understand now, so would 50k trim be too much in here or does that sound about right? or should i go 500k?
website: www.mohawkstudios.co.uk
email: [email protected]

If it hisses its probably the wrong impedance!!!

Rob Flinn

Re: The best noise gate?
« Reply #26 on: December 29, 2018, 11:52:54 AM »
I would be surprised if you need 500K but I'm no expert.
regards Rob

abbey road d enfer

Re: The best noise gate?
« Reply #27 on: December 29, 2018, 01:11:30 PM »
ah ok, i understand now, so would 50k trim be too much in here or does that sound about right? or should i go 500k?
My simulation shows very little difference between 50k and open circuit. I would suggest a 500k trimmer with a 50k padding.
BTW I think there are some errors (or red herrings) regarding the values of some resistors; the 33k in the collector of the 4th transistor (3704) seems a tad high, and the 3.3k across e-b of same transistor should be increased. With the values on the schemo, the voltage at the collector of the 5th transistor (across the 0.47uF cap) never gets negative enough to open the FET.
I know that sim is not the real world, but this needs to be investigated.

On another subject, I think that EQing the side-chain is vital in any noise-gate; the second product I put on the market was a noise-gate I co-designed with an ex-Dolby guy. The gate in itself was nothing fancy - unashamedly inspired by MXR (!), but the filters (2nd-order Sallen & Key) made a difference. It was an instant hit. There was nothing comparable on the market at the time.
« Last Edit: December 29, 2018, 01:22:03 PM by abbey road d enfer »
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

Spencerleehorton

Re: The best noise gate?
« Reply #28 on: December 29, 2018, 01:42:35 PM »
All great info thanks, I will put this together first and put trimmers in those places so it can be tweaked!
Once done and working I think the next step is putting something in the circuit for sidechain eq’ing for better gate response.

Any thoughts on how to implement the sidechain with eq?
website: www.mohawkstudios.co.uk
email: [email protected]

If it hisses its probably the wrong impedance!!!

JohnRoberts

Re: The best noise gate?
« Reply #29 on: December 29, 2018, 02:05:50 PM »
All great info thanks, I will put this together first and put trimmers in those places so it can be tweaked!
Once done and working I think the next step is putting something in the circuit for sidechain eq’ing for better gate response.

Any thoughts on how to implement the sidechain with eq?
I have already posted about that, perhaps more than once..

#1 Easy and most powerful is an insert jack that allows you to patch in a powerful external EQ for problem tracks.
#2 2- knob Baxandal type shelving treble/bass tone control Eq
#3  1-Knob tilt EQ

A classic concern when putting multiple gates with side chain EQ inside a single chassis is front panel space for all those knobs, not to mention gate threshold, (optional) hold time, (optional) attenuation depth, etc.

Pick your poison. (I've used door #1 and #3 before).

JR
John Roberts
http://circularscience.com
Tune it, or don't play it...


Rob Flinn

Re: The best noise gate?
« Reply #30 on: December 29, 2018, 03:09:53 PM »
#1 Easy and most powerful is an insert jack that allows you to patch in a powerful external EQ for problem tracks.

 I would debate that this is easy because you either need to tie up an eq or need to build some eq's to insert.    If you happen to have a bunch of patchable eq's that you don't use then  maybe it is easy.
regards Rob

JohnRoberts

Re: The best noise gate?
« Reply #31 on: December 29, 2018, 05:16:14 PM »
I would debate that this is easy because you either need to tie up an eq or need to build some eq's to insert.    If you happen to have a bunch of patchable eq's that you don't use then  maybe it is easy.
Easy from a design perspective...

I ASSume this is a recording interest so tracks are not all happening in real time, all at same time.

Like I said pick your poison. Don't argue with only one option when I offer multiple choice.  8)

JR
John Roberts
http://circularscience.com
Tune it, or don't play it...

Spencerleehorton

Re: The best noise gate?
« Reply #32 on: December 29, 2018, 05:18:12 PM »
Funnily enough I have a 2524 eq project on the shelf which I still haven’t done anything with, it’s the api 3 band eq which I’m sure could help this project, space wise I think i could get 4 x rm68 and 4 x api eq in a 2U with Psu space hopefully.
Front panel design would be tight, but defo possible I reckon!!
website: www.mohawkstudios.co.uk
email: [email protected]

If it hisses its probably the wrong impedance!!!

abbey road d enfer

Re: The best noise gate?
« Reply #33 on: December 29, 2018, 05:18:38 PM »
Any thoughts on how to implement the sidechain with eq?
My personal take is a High-pass and a Low-pass, à la DS201. I've used EQ's, both parametric and graphic, in insert; I've not found it was any better.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

Spencerleehorton

Re: The best noise gate?
« Reply #34 on: December 29, 2018, 05:20:53 PM »
Ok so high pass a slow pass sounds good, could we have some docs attached so I can see how and where to implement please.
website: www.mohawkstudios.co.uk
email: [email protected]

If it hisses its probably the wrong impedance!!!

Rob Flinn

Re: The best noise gate?
« Reply #35 on: December 29, 2018, 06:07:28 PM »
Ok so high pass a slow pass sounds good, could we have some docs attached so I can see how and where to implement please.

You could look at the Drawmer Ds201 3 page pdf.   The first page has the filters between where it says "keysource" & "threshold".
regards Rob

Re: The best noise gate?
« Reply #36 on: December 29, 2018, 06:20:19 PM »
Mostly you want to pick a narrow range of frequencies to trigger your gate , LFcontrol  on the ds201 goes all the way from 25 hz upto 4khz and the Hf control is from 250hz upto 35khz so you can really narrow down the range if needs be ,this really helps the gate to open and shut smoothly and when you want it too . If say your gating a tom , you want to minimise any spill in the control signal so that the gate doesnt trigger falsely , the key filter on the Ds201 is near perfect for this job .

For me theres two distinct reasons for gating , one a simple noise gate , very much like used in basic guitar stomp boxes and to some extent large console gating, its on or off with a miniumum of artifacts   , then you have  gating with manual settings for threshold ,attack, hold, release and range ,this is a different beast completely and its usage goes far beyond noise control .

Sorry .Png wont post for some reason ,
Its all included in the link to the service manual I put up

« Last Edit: December 29, 2018, 06:26:48 PM by Tubetec »

Re: The best noise gate?
« Reply #37 on: December 29, 2018, 06:43:04 PM »
Just had a quick look at my Ds 201 , sure enough its unbalanced ,with only the ground  and tip of the plug connecting on both input and output jack.
The spec sheet quotes 10k unbal 20k balanced  ,but the unbalanced version must be more like 1 meg instrument input .


Spencerleehorton

Re: The best noise gate?
« Reply #38 on: December 30, 2018, 03:06:01 AM »
Still not quite sure which 3.3k resistor you mean to be bigger?

Is it the one attached to the collector of the 4th transistor or the base of the fifth?
website: www.mohawkstudios.co.uk
email: [email protected]

If it hisses its probably the wrong impedance!!!

abbey road d enfer

Re: The best noise gate?
« Reply #39 on: December 30, 2018, 04:29:50 AM »
Still not quite sure which 3.3k resistor you mean to be bigger?

Is it the one attached to the collector of the 4th transistor
That one.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.


 

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