Anyone interested to build a TG1 clone ?

[strangeandbouncy]

Dear Tom,

i personally don't find much similarity between TG and 33609! Neve is extremely flexible and can be relatively subtle and transparent. TG is a very different beast. Subtlety is not really in it's vocabulary. i regularly use both. I have also used original TG console many times. I fond that the original channel comps are a bit more subtle than the chandler, but not a lot! These puppies REALLY suck, and i say that with the utmost of respect! I do find the EMI to be a bit of a one trick pony to be honest, but WHAT a one trick pony! Awesome on guitars, bass, acoustic, etc, etc. Somewhat uncontrolable on a sub-group/mix-bus imho, unlesss you want that "Effecty" sound. Rather like the SSL channel comps, they are great as a bit of compression in addition to whatever else you fancy when mixing on a TG Console. I am NOT comparing them to the SSL channel comps, tho!

Suck 'em and see!

Andy P

 

[Rob Flinn]

Also, please forgive my ignorance, but what exactly are the things immediately to the right of the bit that says "VT13 and VT14 to be matched according to item list" on the bottom of page 1 of Colonel/Professor Winston O'Boogies fabtastic schemo? Is it a transformer?

They look like 4 different wafers in a rotary switch to me. Just a weird way of drawing them maybe.

 

[soundguy]

hi andy-

Ive never measured the transformers in the chandler box. It would be interesting to see what was used originally though.


[quote author="TomWaterman"]
would like to have a play with a 33609 / TG1 type comp at some point, I have a sneaking suspicion that they'd be great on drums/room etc. For some reason I was led to believe that the TG1 was a fair bit dirtier than the 33609(?)[/quote]

the emi limiter is definitely way dirtier than the 33609 and it will suck quite a bit more of the room out as well, but so far as a general comparison goes, those two boxes do a very similar thing. For instance, I think the emi and the 33609 have a lot more in common sonically than the 33609 does with a 2254 and all three are diode bridge limiters. Much of the sound of the 33609 is the opamps crapping out. That box gets really poofy where the emi gets really distorted. Ive always used both of mine somewhat interchangably. They both suck for not having an attack control, thats for sure. This would be a nice feature to add if anyone is keeping score.

Its amazing that two of the worlds most reknown buss limiters dont have an attack control...

dave

 

[JLM Audio]

The EMI & NEVE are completely different compression elements that work on different principles.

The Neve diode bridge compressors use the diodes to clamp the signal down forming a variable pad.

The EMI uses the fact that as the current in the zener diodes is increased the Tranconductance (resistance) becomes less giving less gain in the differential pair.

VT13 & VT14 are BC109 or BC184 that have to have there gain matched to keep the compression symmetrical on positive and negative going audio waves.

To add adjustable attack in EMI change R47 to 2.2k in series with lin 100k pot.

Joe

www.jlmaudio.com

a Mu compressor is a VCA compressor

 

[TomWaterman]

Ahh thanks guys!

Joe - you rock!! Great info.

Does that mean a possible reason the TG sounds dirtier is because of the transconductance in the diff.pair causing slightly asymmetrical gain change = distortion?

-Tom

 

[soundguy]

[quote author="TomWaterman"]
Does that mean a possible reason the TG sounds dirtier is because of the transconductance in the diff.pair causing slightly asymmetrical gain change = distortion?
[/quote]

that certainly makes a ton of sense to me.

After having used this thing for a year or so, I think when I build one that jensens on the output at least would really be a benefit. Carnhills are really a lousy choice. I feel like they take an already inefficient design and make it even less efficient. I suppose if you dont have any neve stuff its a total non issue, but changing the transformers to a cleaner sounding output would benefit the box in a good way from whats currently available.

dave

 

[strangeandbouncy]

Soundguy,

Many relatively unknown fabulous compressors have no attack controls. My Pyes and BBC6/17's, Valley fx, Decca's, Altec1620, (and their direct descendants the DAV), NTP's etc etc etc are bereft of suchlike . . . . .


Andy P

 

[strangeandbouncy]

Rob Flinn,


Thanks for the reply. Notso sure myself . . . . for one thing all the controls in an EMI are accounted for without those thingies(Comp/lim, hold, recovery, and output).


Anyone else fill me in?


Andy P

 

[soundguy]

[quote author="strangeandbouncy"]Soundguy,

Many relatively unknown fabulous compressors have no attack controls. My Pyes and BBC6/17's, Valley fx, Decca's, Altec1620, (and their direct descendants the DAV), NTP's etc etc etc are bereft of suchlike . . . . .


Andy P[/quote]

I know. they could all benefit from the addition of an attack control too. For something to work in series on a buss, an attack control is really really important. I wind up using all these boxes with fixed attack on parallel busses alot of the time just because of that.

dave

 

[fazeka]

Found this deep within my harddrive from ages back. Cannot remember where I got it. Maybe y'all'll find it useful? Usual disclaimers. YMMV.

Some notes on the use of a Zener Diode Limiter

1.1 A novel feature of this limiter is that the quiescent gain, which is indicated by the limiter meter, can be set to any value between 0 and 20 dB by the Hold control. This arrangement provides better signal/noise ratios to be realized than are possible with a conventional limiter capable of 20 dB of limiting.

1.2 To obtain the best signal/noise ratio the quiescent gain should only be sufficient to allow the desired degree of limiting. This condition will be found by adjusting the Input Level Control so that the limiter meter occasionally peaks just into the upper red band and then the Hold control so that the desired degree of limiting occurs.

1.3 The gain ? v ? level characteristics are similar to those obtained from Fairchild 660 Limiters and Altec ???24 Compressors particularly if the quiescent gain is set between 15 and 20.

1.4 The quiescent gain should not be set higher than 20 dB as there would then be a risk of distortion.

1.5 The upper red band on the limiter meter represents the first 3 dB of an 8 dB overload region. In this region distortion (of 1 kHz tone) is usually about ½% total harmonic distortion but above this region violent clipping will occur. The meter together with its driving circuit is a peak level indicator to facilitate avoiding overload.

1.6 Distortion, using any limiter must increase as the programme frequency falls and as the recovery rate increases because the gain will then vary significantly throughout each cycle of the programme waveform so altering that waveform. Positions 1 to 6 of the Recovery control provide recovery time constants of 50 ms to 2 s in approximately equal steps each of 2 : 1. Position 2 (100 ms) is about the same time constant as that of a Fairchild limiter set to Recovery position 1.

1.7 When a large safety factor (to cope with artists who produce inconsistent peak levels) is of major importance the Hold control should be set to give a large quiescent gain of say 20 dB (quiescent meter indication of "20") and the input level correspondingly reduced. Then for normal programme peaks on which say 5 dB of limiting is obtained the meter will swing from "20" to "15". Exceptional peaks may be 15 dB higher before the meter will reach the red region and there is a further range of 8 dB "in the red" where distortion will be only about ½%. Using the limiter in this fashion will produce a peak output level only 1 or 2 dB lower than that obtained when using as described in para. 1.2. If used as a compressor however the peak level would be substantially lowered.

1.8 For normal "Pop" working a compromise between paras. 1.2 and 1.7 is recommended ? say Hold set to "10".

[unquote]

 

[strangeandbouncy]

Dear Soundguy,

If you use them in series, I find that it depends where in the chain you put them . . . i do accept that that sometimes you just can't use, say, a Pye, that you'd LIKE to use for it's sound, and it's action is just too fast . . . then I put it later in the chain, and let something more flexible take the "choking" outta it first! More often or not, they sit on stereo busses before the mix-bus, just waiting for something to be dropped into them . . . I couldn;t work without ;em!

Andy P

 

[strangeandbouncy]

Dear All,

i am still hoping someone can tell me what transformers are used in/out of these, i read here of Carnhill and Jensen. Someone told me that originals are Gardners. Cool! - but what impedences/stock no.s? Are they 1:1/600Ohm or what?


Thanks as ever, Guys!


ANdy P

 

[Rob Flinn]

Thanks for the reply. Notso sure myself . . . . for one thing all the controls in an EMI are accounted for without those thingies(Comp/lim, hold, recovery, and output).

The reason I say it looks like a rotary switch is that if you compare each of the 4 things your talking about to the other rotary switches on this diagram they are the same format & also there is evidence that they are ganged together.

 

[strangeandbouncy]

Dear Rob,

Please forgive me, I did not mean to be off-hand . . . . i shall open up the next chandler i comes across and ascertain! I concur that they apppear to be ganged, (as i said originally), but cannot for the life of me make 'em out! for one thing, what would they be switching? Ho hum!

All the best,

Andy P

 

[Rob Flinn]

Andy

There was no offence taken.

I agree with you that its not easy to work out what it does , but I just can`t see that its anything else but a switch. If you get the chance to open one up I`d be very interested to know more about this box. Would there be any chance of taking some pictures ??

 

[soundguy]

[quote author="strangeandbouncy"]i am still hoping someone can tell me what transformers are used in/out of these, i read here of Carnhill and Jensen. Someone told me that originals are Gardners. Cool! - but what impedences/stock no.s? Are they 1:1/600Ohm or what?[/quote]

andy-

I think the original used gardners. The chandler thing definitley uses carnhill. Next time I open it up I'll try to measure some stuff, thats not going to be any time soon though. I remember reading the last time this came up someone mentioning a 10468 on the input. The line amp doesnt seem to require a gapped core, so for the time the thing was developed I would be suprised if it used a step up greater than 1:2. My chandler has a more than reasonable amount of gain, if the OT is wired 1:2 I bet you could get away with a 1:1. I have photos of the chandler but despite my frustration with it, out of respect for the guy's currently in production product Im reluctant to post photos here...

dave

 

[strangeandbouncy]

Soundguy,

Many thanks for info. I have a few 10468's already! i have some big-old Gardeners too. 10k bridging and perhaps some 600/600. We'll see!

Andy P

 

[ToobieSnack]

plz post or e-mail me some pics please.
BTW: as far as I know you can build anthing you want as long as it's for experimental/educational purposes.
i know I could learn some things building one of these....
thanks
TS

 

[Tekay]

Andy & Dave!
The output transformer is wired as 1:3.46 / 50:600ohm that's +10dB.

Also noticed that the 180p was missing over the 10468 sec, and that the transformer feeds the 10k holdpot without any more resistor as load, normaly the 10468 needs 4k8/180p to be flat.

 

[leigh]

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