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Forum: General Discussion

Topic: Anyone still using Rotary Mixers ? - Page: 2

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pern wrote :
cstoll wrote :

Here is a link to the reborn 1620LE from Soundcraft -http://www.ureidj.com/product_1620LE.aspx

Unfortunately it died off very quickly because the demand just was not there and it didn't exhibit the same level of warmth in the sound that the classic UREI 1620 does.


This is very interesting. Do you like the sound of the Original 1620 ? Do you remember what people didn't like about the sound in detail of 1620LE ? I have been looking at the schematics of the "old" UREI 1620 and it's a very simple and clean design, and from what i can figure out the LE version have just used newer components and skipped the transformer on the output.


The Soundcraft UREI 1620LE was produced as a Limited Edition (LE) to see if demand would be there for long term production. The problem is that it wasn't and production was stopped. Never hear the LE and how it sounded, so can't comment.

The original UREI has a very very warm sound to it. Most mixers are either typically heavier in the Low-Mid or Mid-Hi so most always tend to have to compensate through EQs on the mixer or external. With the UREI you can run at zero on the Treble or Bass knobs and you just experience the warm and full sound from Hi to Low. The mixer is one of the most balanced mixers I have ever worked with.

As I said I have worked with the XONE:V6 and it was very close to the UREI except if I was to compare the to like a summer day - you knew you were standing in the sun with the V6 -- it still had the warmth but it was a bit brighter in a uniform way.

Here is a document (if you hadn't found it) that you may want to download -
http://www.jblproservice.com/pdf/Vintage%20JBL-UREI%20Electronics/UREI-1620%20manual.pdf


And to answer your PM ... I don't know the dimensions ... but I know you can find 'replacement' knob kits out there.
 
Thanks for the info, just trying to find out exactly what components in 1620 that gives that specific sound. But i think i know what it is now.

Yes, i have that manual already and i have found spare knobs, but not for the faders yet. But i'm still looking.
 
pern wrote :
Yes, i have that manual already and i have found spare knobs, but not for the faders yet. But i'm still looking.


Faders? There are no faders on the mixer.
 
cstoll wrote :
pern wrote :
Yes, i have that manual already and i have found spare knobs, but not for the faders yet. But i'm still looking.


Faders? There are no faders on the mixer.



True, in a rotary mixer they would be potentiometer. Also known as a three terminal resistor.

In the late 80s I worked one place the crossfader was verticle...took a while to get used to it...
 
cstoll wrote :
pern wrote :
Yes, i have that manual already and i have found spare knobs, but not for the faders yet. But i'm still looking.


Faders? There are no faders on the mixer.



Sorry , typo from me. Input Channel Volume Rotary Potentiometers ;-)
 
* 1st step, build a reference mixer. *
--------------------------------------


Since i cant get my hands on an original UREI 1620 but really want to hear myself how it sounds etc, i will build one and have as a sound reference for the others.

It will be built from the original schematics but with some minor changes:

- Built in a 19" 1U box
- Added CUE - MIX function
- Added mono LED VU meter. Might be stereo, not sure yet.
- Added Effect send for Mic
- Removed EQ

Each channel have a 2 input select swich. So available inputs are:

- 1 Mic
- 2 Phono
- 3 Line


This is how it will look like (But all LEDs will be blue ones) :
 
* Rotary Reference mixer. Part 2 *


After googling a lot i have learned that the UREI EQ affects the sound even when it's in "0" position. So i have to add that, and then i will add the balance funtion and source select also to get a 98% TRUE 1620. But this can't fit in a 1U box and at the moment i don't want to do a 2U.

So i have decided to do a small desktop version of it since i actually need one. This will also be MUCH cheaper to do. The dimensions are 160 * 220 * 50 mm.

This is how it will look:



(* HP Vol is located on the front)


And this is the box i will use:



Now it's time to start up the PCB CAD ;-)
 
pern wrote :




Nice pern. I do like this simple layout mate.

I might be interested in one mate, if the price is right ;)
 
Looks like it will be a nice unit. Interesting to hear the results.
 
The only issue i have now when selected a smaller box is the output stages.

The are 3 options here:

- Unbalanced
- Balanced, No transformer
- Balanced using transformer

From a design view i would prefer one of these.

- Unbalanced
- Balanced, No transformer

But i haven't decided yet but at the moment i thinkit will be - Balanced, No transformer
 
Can you implement a flip switch for using or not using the transformer on the balance output ?
 
What would be a nice touch on a later model (mk2 maybe) is replacing the Led's, with 2 old fashioned looking meters.

Then that would make it look really nice, but I guess I'm jumpin' the gun here abit, lol
 
No,

- Balanced, No transformer
- Balanced using transformer

Are 2 complete different designs. I have to choose one of them.
 
jimmy b wrote :
What would be a nice touch on a later model (mk2 maybe) is replacing the Led's, with 2 old fashioned looking meters.

Then that would make it look really nice, but I guess I'm jumpin' the gun here abit, lol



The LED Meter is a separate PCB so that is possible, the problem is to find a small, good and cheap VU - meter.

 
pern wrote :

The LED Meter is a separate PCB so that is possible, the problem is to find a small, good and cheap VU - meter.



Good point
 
pern wrote :
No,

- Balanced, No transformer
- Balanced using transformer

Are 2 complete different designs. I have to choose one of them.


Hmmm ... If going for the more authentic sound I would say 'transformer'.

If you look at the schematics the booth output is unbalanced. So couldn't you have Balanced (Transformer and no Transformer) for House output and if you need unbalanced use the Booth output?

Not an electronics engineer ... that's your area ... just tossing ideas.
 
In this test version the BOOTH output will be 100% as the original schematic, so no balanced output there. For HOUSE i will do 2 different PCB designs, with and without trafo. I'm not just thinking of my own testing purpose, also if anyone else want to use the design but doesn't want the transformers. 2 HQ transformers is about $ 125. about $ 110 more in material cost than the version without it. And a HQ transformer doesn't affect the sound. A bad one does affect the treble a little bit.

But when i build the 19" 3U rotary mixer after this one, everything will be in modules. Then you can pick and choose whatever you want. Including mods/extensions that will also work with both 1620 and 1620 LE.
 
 

Very Nice Chris

I'm loving the mixers now, Very cool
 
jimmy b wrote :

Very Nice Chris

I'm loving the mixers now, Very cool




Welcome to the darkside.......
 
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