EMI RS124

[DaveP]

ED,
Cool design too, Mich! Is that a real Altec meter, or a re-purposed Jewell MM2? Funny, they still make that same old meter.

The Jewell meter was from surplus sales and had a reverse scale, too hard to reverse it, so I hacked the back and fitted a 100uA movement.  Downloaded hi res picture of original off the web and printed the scale and stuck it on original faceplate.  It works fine and is just a visual indication of whats going on anyway.

I fitted the extra tube, not only for the stability, but because I didn't have the correct input TX.  According to one of CJ's tear-downs the original is a step-up of about 1:2.5 (don't quote me, read the thread) so I was going to be short of gain compared to the original.  Abbey Road must have changed it too because they used a 200 Ohm standard in their studio.
DaveP

 

[ed rees]

Cool, I got mine NOS on ebay. Jewell actually still makes this type of meter!

Here's my 124 so far. Hand drawn meter face is temporary, of course. Out of printer ink...

I'm just going to use printable decals for the faceplate labels, until I get my CNC engraver going this winter. Should look fine for now.

 

[rotheu]

Great job on the metal work!!! Did you make it from scratch?

 

[ed rees]

Thank you, Yep! Bandsaw, drillpress, vice and hammer. Making the top and bottom covers tomorrow. Also thinking about using my drillpress and a file to lathe the original style lamp housing from aluminum.

 

[meverylame]

I could be wrong. But talking to John Hinson's (temporary) partner,  had told me the RS124 has nothing to do with a 436 except the chasis, the meter and the transformers.

 

[ed rees]

The tubes and basic archetecture are also the same, just lots of changed component values, and function additions. I'm sure the people making these to sell don't want us knowing how simple they are.  

I guess the closest I'll be able to do is A/B my build with the VST plugin and see how it checks out?

 

[rotheu]

RS124 has nothing to do with a 436 except the chasis, the meter and the transformers

What really get's me is this "overhyping" of everything vintage, all this "mystery", secrecy and speculation around it. It's just a freakin PA grade cheap ass compressor with few modified components to make it more suitable for studio use, that's all it is. Yes it's a nice tool, it's sounds really good, but too slow on release times IMO, but nothing more. People, please, take it for what it is. Chassis, transformers and tubes are the same? What else is there??? 30K for Fairchild??? Genius design, beautiful sound, only three useful time constants and a lot of work to actually build it? Yes. But wouldn't 6K-8K be more realistic price for that COMPRESSOR? For 30K I will expect it to make me coffee every morning for the rest of my life and maybe give me BJs ones in a while. But that's just me, tell me if i'm wrong.

 

[shabtek]

No, you are correct; $30k for coffee and occasional BJs is considered a good bargain stateside.

 

[DaveP]

I agree too, far too much hype.
But I actually think that simple is best.
To have your audio going through just 4 tubes has got to be better than through several hundred (1000 even?) transistors in umpteen IC's.

The other point of the RS124, is that if the Beatles managed to make their sounds with it then we at least are on a level playing field using the same gear; the rest is down to talent.

As for the other services, I can personally testify that wives cost a lot more than $30k

DaveP

 

[gary o]

I also agree with with the point about the hype but have also read some recerse hype ie the 436 being PA gear many owners saying they are shite lots of peopl here have rubbished them.....but seems to me the EMI chaps thought they were worth modding so here we are...

I also believe simple is good less is more sometimes maybe the people that didnt like there 436s had knackered out of balance ones that sounded crap at the time.

Im intrigued by the 436, I built a point to point VK1 that sounds great to me, Im gonna P2P a 436 now to compare then add the maybe EMI mods and compare again

Thanks for info guys in this interesting thread

Gary O.

 

[emrr]

Let's have another perspective.

Possibly EMI bought Altec because the engineers deemed them to be the platform most easily modified, in terms of existing layout and feature set.  And distribution channels were easier too. 

Most of the other available limiters are much more packed, and not as easily stripped down for rebuilds. 

They certainly didn't pick them based on sound, especially while not having a modified unit for a listen. 

 

[fazeka]

My understanding (and I thought I read this in Recording The Beatles, but am now going off memory) was that when EMI engineers went to a visit at Capitol ca. '59, they saw Altec 436s being used there. This influenced them to purchase the 436Bs they ended up acquiring. And later when they ran them through the paces (like with everything else EMI acquired), they realized that it was not up to their standards (i.e., 200-ohm impedance, etc.) and modified them as they saw fit.

 

[pucho812]

I'm sure you guys have seen this then


http://web.me.com/huge75/Site_2/_Lisson_Grove_R-124.html

 

[emrr]

Well what do ya know, that's Aardman's name.  Surprise surprise. 

 

[fazeka]

D'oh!

 

[QUEEF BAG]

i'm havin' trouble here.  that threshold description...

 
  Quote:
This is a threshold control with a bit of a twist. Basically, the threshold is adjusted in the normal manner, i.e. the more the control is turned clockwise, the higher the ceiling or level at which compression occurs. This is quite common and fairly straightforward.

The interesting difference here is that our threshold adjustment uses the dynamically changing compressed signal as its point of reference rather than a fixed voltage. What this means is that if the control is turned more clockwise, the tone changes slightly adding a subtle sparkle. This seems to be a wonderful way to "tickle" the vocals or a mix.


isn't that sayin' "the less you compress, the more high end you get"?

 

[emrr]

That description is sayin' it works and sounds like every other vari-mu tube limiter I've ever used.  Ratio and threshold are locked together, with more signal level required to overcome the threshold bias voltage.  The tone tightens up at higher ratios/threshold, as opposed to a softer smushy sound at lower ratios. 

 

[Marcocet]

Wow. I think that describes exactly why I like vari-mu compression so much.

 

[gary o]

Iv just solder a very messy point to point version of Rotheus schematic.......& cant get it to work....its amlifies a lot but there is constant oscilation I cant get rid of.....its only an experiment...i havent made the PSU Im using a varable PSU for now but I cant get it to play ball....I been over & over my wireing......Im going to leave it alone for a while have another look later....

 

[JayDubrek]

Finished building one of these last week...sounded quite decent but tonight it's developed a high pitched tone tonight....any ideas what this could be?