Auditronics 501

Hello all!

I have been dragging around an Auditronics 501 I got on the cheap from a client back when we used to edit with razor blades and you actually needed the band in the control room for the mix just for the "automation"... ahh the good ol' days!
Anyway, I saw a couple of posts on this desk in this forum as I am fixin' to get to work on the old girl so I can hook her up to my motu/g5 thingamajig.

I'd be interested in everyones experience with the 501 in particular mods and upgrades and so on and so forth...

Also, any history relating to what recordings they were used on and any other interesting tidbits... oh yeah, who's got one now?

Cheers!

George

 

George, I currently have a pair! That is, all of the modules for a pair of 501's. I recently discarded both frames and the built-in TT patch bays. Sorry. I Still have the manuals, power supplies, knowledge and history, updates, etc.

Which version you got? The one with the left and right monitor buttons? Or the one with the left, center & right buttons?

Silver microphone transformer? Or yellow/beige color transformer?

14 pin LM 709 IC chips? Or retrofitted 8 pin DIP with 5534's, sitting in 14 pin sockets?

Coffee proof Auditronics faders with round or square knobs? Or maybe even Penney & Giles conductive plastics?

Jensen output transformer is with the gray cardboard? Or something else?

What else would you like to know?
Ms. Remy Ann David

 

Hi Remy:
I haven't unboxed the modules yet from the last time I had it set up, but from memory:
left, right, center... I believe silver mic transformers .. 5534s... mixed bag of some crazy auditronics faders, eight or ten Duncan conductive plastic, and I think just four P&G.
I'll have to get back to you on the output transformers.
I lost the original PS and manual from a storage unit. :/ Had to pay $100 for a copy from lighthouse electronics that doesn't include a legible "centerfold" block diagram. Seems they couldn't unfold it!
I have a pile of other PSs here I am trying to match up but I'm having trouble with the +24vdc for the logic part.... thinking about adapting a canakit. Thnk 1a will carry the logic? I have a pretty clean Wheatstone for the +15 and 50vdc.

So, just tell me everything you know 'bout 'em! I got plenty of time!

Talk to you soon!
George

 

Hi George,

Fellow 501 owner, here. I'm less than a year into owning my console and I love it.

I'l dive right in with a comment about the +/-24vdc for the logic circuit; you'll find that all of the lamps are also on these rails and thus will want a bit more than 1a of current. I think I'm running a bi-polar PS at 2.4a and it still runs slightly warm (the PS).

Also, according to many 501 stalwarts, the stock power supply never really seemed to provide the +/-15vdc audio rail juice that a loaded 26 channel desk wanted to see. Make sure your Wheatstones are able to jump up to at least 4-6 amps when you've got the desk filled up with program. I'm actually thinking of picking up a nice Acopian Gold Box supply sometime for my audio rails. They're great power supplies and provide full crowbar protection if either rail goes out of regulation. Considering they're less than $400 - not a terrible investment.

Do you have a molex connection to your power rails on the console, or barrier strip connections? I have the barrier strip and with no manual at all I had to trace everything down before I made all the PS connections and threw the power switch - that was a tense moment. If you need help with your PS connections - I can help. But it sounds like you have some semblance of a manual.

I have to jump off - but I'm always keen to talk about this desk .. I'll catch up with you shortly and am happy to brainstorm right along with you. And - of course, Remy seems like a really great asset for all of us Auditronics folk.

Marc

 

Hi Marc!
Thanks for the response!
I currently have 20 channels which I wouldn't mind expanding to 24 if Remy can be talked out of a few of hers... BTW, Remy your hair really looks nice that way! ;-)
Like I said I have several power supplies here including a large Tangent (which is currently blowing fuses) which I might adapt to do the job. That or find an Auditronics PS somewhere... Remy? ;-)
When I first got the console I did have the PS and although it was literally falling apart, I pieced it together, tested it and fired up the board.
To my surprise, because it was really dirty and neglected looking, I was able to pass a tone though most sections of most modules and the logic worked fine.
I have since cleaned it up nice and after getting at least a temporary PS solution going I will need to look toward caps and chips which brings me to the next big question: What would you think would make the best upgrade for the 5534 for use in this desk?

I'll be painting my new temporary control room (spare bedroom) and setting up the board in it hopefully this week. With a little luck I can get started soldering and have a few modules running soon.

Talk to y'all soon!

George

 

I have the modules you want to fill out your console. Thanks, my hair looked nice that day. Did you say you want some modules?

If you have the left, center, right monitor buttons, that's a type I, 501. That version had the factory made microphone transformer originally and is a puke yellow color. The console may have been upgraded with the Jensen JE110KE microphone transformer which appeared on the later type I I 501 consoles and later 110 series Grandson consoles. I have 26 of the type I and 20 of the type I I. I'm asking for $400 per complete input Channel. Which is fader, I/O module, 16 Channel switcher. Prices are negotiable. Get them before eBay does.

I have original 501 and 110 series manuals that I will soon scan and make available to those who may need them.

Quadra-phonic? What's that? A Quadra-phony.

Of course, I think it was genius that they called the console a 501 . It wasn't quite 5.1. I guess it was 5.01 way back in 1970?
Ms. Remy Ann David

 

http://www.diyfactory.com/data.htm
Auditronics 501 - Son of Grand
Draft 1 - A draft copy of the re-typed, main text section of the manual
Draft 2 - Section 6 - just a short list of the main schematics

http://www.diyfactory.com/data/A501draft_text_only.pdf
http://www.diyfactory.com/data/A501draft_section_6_short_list.pdf

one day I might pull the finger out and complete that 501 manuals project
but for now that should be enough

I loved my 501 desks
... had one of each
... the left, right, front and back
... and the left, centre, right, rear version

modded with 5534 opamps
and
the new owner has built his own design power supply

had enough channels for 26 but chose to run only 24

when running a Tascam 38 and synths , I changed the gain structure of the line inputs to better make use of headroom
... later reverted back to standard when the ProTools and 888 and 888/24 units were purchased.

I now just do things ITB these days
:shock:
well actually
that's not quite true
the HD system remains unused with the new ... (now old)... computer (dual 2.3) still in the box
:roll:
I just surf these days ... that's in the water and not the net

 

Actually Remy, are both of your PSUs still pretty much working? I might have more immediate use for one or both of them.
Too bad the rest of the two consoles got trashed... I guess that's the way it goes - worth more in pieces :/
Anyway, it's my poor-mans-api.

Thank all of you guys (and gals) for the help... I'll post again when I've got her standing and can look her over again.

Cheers!

George

 

ready to power-up my 501!

Hello all!

I finally unpacked the console and set it up in the spare bedroom.
I found a homemade power supply on ebay for the logic, +/- 24vdc @ 3a per rail. I'll use the audio arts supply for the audio for now until I can see about fixing a rather large tangent psu I found a while back which blows fuses. If I can get it working it's rated at 4a per rail for the +/- 15 and also has +50vdc for phantom power.

Marc,
I need your help on the psu connections at the console. While I'm glad not to have the molex connectors at that part of the board, I have no idea how the 20 screw terminals are assigned. None of the prints I have provide that info -- molex only.

Also, as for the other molex connectors on the console, do you know of a source for new females and pins for these? I saw some molex connectors on ebay including 12 pin females but on closer examination of the photos they appear to be of a different type. What do you think?

Other things I'd like some feedback on include:

1) Whos 5534s do you like best and are some of the newer hi-fi versions going to need further mods to use in these circuits? I have 301s and 709s and also have the upgrade instructions from auditronics ,Thanks to Kev, but am wondering if there are significant differences with these newer chips install-wise.

2) Where would you start recapping-wise? Silver (electrolytics) coupling caps found throughout the board? What do you like for replacements? Any specific types of Film and foil? What about small bypass caps in addition to replacing what's there?

3) Where can I find replacement bulbs for the meters?

Thank you all for your help!

George

 

change meter lamps to LEDs
experiment with ones with a yellow tone as it looks more retro

as the bulbs blow the other bulbs run hotter
beware of melting on the plastic of the meters

change to LEDs

ALL of the newer IC will probably draw more current ... it all adds up and may put strain on

the PS

must use NE5534AN ... I think mine were Signetics ... don't quote me there
standard or fake 5534 just won't cut it

the newer BurBrown and similar may offer something but you will have to experiment as they

all have a different sound
...
some people don't like the very high speed sound ... dry , brittle

Electros
again experiment and get quality Audio caps
105 degrees ... low leak ... low ESR
ask Joe at JLMaudio what he is using at the moment as these seem to work fine
I've used many brands in the past and it's more about the model and batch than just manufacturer

when you say bypass
do you mean adding a resistor/cap for each power leg of the IC's ?
nice
big job
lots of track mod

the more you do this the less it is an Auditronics 501
this mod/improve verses restore is an issue common with restoring OLD cars
OLD cars with electronic ignition is cool for economy and everyday use but it's not retro
OLD cars with electric windows is well ..... ?

same goes for old desks
do you want retro
do you want collector
....
do you want everyday use

???


I think to lose the 301 and 709 is OK ... a must really
I did the NE5534AN and it wasn't too much of a departure from the A-501 - Son of Grand
use quality machined IC sockets


keep asking questions

 

Re: ready to power-up my 501!

I used the signetics 5534an, they sound good to me.

i replaced all the electrolytic coupling caps and all of the tantalum bypass caps with low esr electrolytics. each IC has a .1uf ceramic bypass cap in addition to the 10uf bypass, so i think you're in good shape there. i used nichicon PWs for the bypass caps and vishay bc axials for the coupling.

also, you might want to try replacing the tants in the EQ with something else. improved the sound a lot to my ears...can't remember what i used though.

 

Mouser has a NE5534ANG in stock - think they'll work? They are made by "ON Semiconductors" who I've never heard of. Anyone know anything about them?

When I mentioned bypass caps what I meant to call them was SHUNT caps, apparently used across electrolytics to make them sound more transparent. I read about this a couple of years back in a reprinted 1980 Audio Magazine article about Picking Capacitors although it was a bit over my head and I have no idea how to calculate what value and type of cap to use as a shunt for the hundreds of 300uf 10v coupling electrolytics throughout the console. The article also suggests that ceramic caps, while stable and long lived produce considerable distortion when used in the audio path. Any specific locations in the IM circuits where you think a better cap might make a significant improvement?

I expect I'll power it up as it is and see where I stand and then start with four to six of the input modules upgrading all of the ICs and changing out the old electrolytics and then I can experiment with film and foil caps for the eq and maybe a pair of paper/oil/foil caps in the mic pre just for fun!

Meanwhile, I am still in need of a motherboard print for the version that uses screw terminals to connect the power supply(s). It has twenty screw terminals labeled only 1 - 20. BTW, neither of the PSUs I have have an over voltage "Sense" function like the original had... do I need to put in a couple of jumpers? Later on I can make a latching relay to make use of the on/off buttons.

I have lots more questions!

Thanks so much for your help!

George

 

are you saying you want to bypass the 'sense' voltage ?

the shunt caps is a personal preference thing
as is the Tant in the signal path

some people like it and some don't

you will have to try these things ands decide for yourself

DON"T get stuck into the EQ section
leave it as is until you know the desk
the Auditronics Simple EQ is the best bit !!! inductors !

chips and power supply and power supply caps is an easy choice

then the audio coupling caps
this needs experimenting as NEW caps might negate some of the ideas in the 'Picking Capacitors'
we luv Walter G. Jung
in many (most) respects the fundamentals haven't changed

but leave the EQ/ timming caps much much later
perhaps never change them

 

Kev asked:

I don't know. I no longer have the original power supply (vanished from storage) and am using, or will be using, two separate PSUs - one for logic, the other for audio and phantom - neither of which have any provisions for "sense voltage". In the original PSU, wasn't that an over voltage protection circuit? Is the actual sense part of it contained in the console where I could still use it to trip off a latching power relay, or was that all in the Auditronics PSU?

Earlier in the string Marc, aka modularlife said he had the screw terminal layout but he hasn't checked in yet...

Marrrrc, where are you???

I'm really itchin' to hook these PSUs up and switch it on and neeeed to know what terminals to hook what up to!

BTW Kev, I love your idea about the LEDs... I will do that after I have the input modules all up and running - even if with the old chips. I'll take your advice and go slow and deliberate on the cap changes, particularly in the eq section.

 

yup.

i've never heard much of a difference with a shunt/bypass cap across a quality 'lytic in the signal path...if i were you, i'd get enough of a few different quality caps, maybe nichicon PWs and vishay BCs and maybe one other type, and do three pairs of channels and see what you like best, then go back and do the rest.

i'd also replace the tants at each IC for the power filtering. I had a few that shorted and burnt and messed up a couple of the routing modules.

i have the screw terminals on my board, but for some reason the documentation is all for the molex type. i have some down time next week, i can probably trace it out for you while archiving some old sessions.

 

My Desks were set up as sense voltages
not just over voltage

for testing purposes ... and perhaps perminantly
there is no harm in set and forget
except
IF
there is a big change in voltage as the modules are removed

when I was testing my supply had enough grunt to NOT notice

the danger is that when 26 modules are in then the volts are normal +/-15 volts ...
I don't remember what I had ... 16 to 17 volts I seem to remember

anyway
as you remove module the volts might climb
22 to 24 ... more
this might be too much and the 5534s will go
as might other things

YES to the high quality nichicon and vishay components ( from catastrophic )

THAT SCREW LAYOUT should be on my site
in the draft manual section
???
I can't find it
:shock:

a very hard to read damaged piece of paper

YOU MUST DOUBLE CHECK THIS INFO
could be for a Molex Connector
1 +15v
2 15v common
3 -15v
4 + sense
5 common sense
6 - sense
7 +34v
8 24v common
9 -24v VDC
10 +50v VDC
11 50v common
12 SPK change over logic
13 auto tape logic
14 +24v VDC
15 24v common

Better Info
from a sheet of one of my power supplies
but again
hard to read

1 +15V (ORG)
2 15V COM (BLK)
3 -15 (BLU)
4 +15 sense (WHT/ORG)
5 SENSE COM (WHT/BLK)
6 -15 SENSE (WHT/VIO)
7 +24 VDC (RED)
8 24V COM (BLK)
9 -24 VDC (PUR)
10 remote on/off (WHT/PUR)
11 remote on/off (GRN)
12 see note 4 (RED)
13 see note 4 (YEL)
14 +50
15 COM
16 see note 2 (GRN) ... capacitor and 100 ohms earth magic
17 see note 2 another earth ... chassis I think
18 (BARE) and another earth

note 2
in some installations the jumper (terminals 16 & 17)
must be removed to prevent ground loop

note 4
remove strapping (terminals 12 & 13 )
for remote "on-off" operation

notes 1 and 2 are about capacitor and resistor values

I can add more IF you need it
8)

 

Thanks Kev!
I'll give it a try over the weekend... :::crossing:fingers:::

I've got some TT patch cables on the way and have a couple of snakes around here, what I'd like to find is a source for the old style 12pin molex connectors, or at least the proper pins for them - I have most of the old females still attached with chopped off wires sticking out of them -- it'd just be nice to start fresh on the connections.

Talk to y'all soon!
George

 

Hey Guys:
I got sidetracked over the weekend but I'll try and get the PSUs connected this week. I have some connectors and things coming in the next few days.
Meanwhile, I've been looking at caps.

Kev says:

And Marc says:

Think these will work? VISHAY BC 330uf 10vdc — Aluminum Electrolytic The temp is only 85 C, but that's pretty hot, yes?
(Here's the PDF)
By the way, the module itself has 300uf 10v silver coloured electros but the print (I think) indicates 330uf. Think it's close enough?
If y'all think they'll do for a start I'll order enough for 16 or so channels and also get a handful of cheapo (but audio rated) panasonic and rubycon electros to play with along with some polypropylene films for the opamp bypass circuits. I wont be messing with those 'till I get the others going but I'd like to have them onhand.

Talk to y'all later!

George

 

gut feeling
???

ordinary
not enough volts
+85 C

I haven't got something better to show you but I'm sure you can do better

these don't look like low ESR
...
note low ESR is not a prerequisite for an audio coupling cap

there are BiPolar Audio caps out there
you may want to try

 

the vishay BCs are probably quite similar to the caps that are in there (when they were new). I used them in my console, can't remember which series. a more "hifi" cap might sound a little "better" depending on what you're looking for.

all in all, the differences to me are not that night and day. more important things like mic placement will certainly make a bigger difference over which cap of decent quality is in the audio path. it also depends on the circuit and all of the other surrounding components. thats why i suggested you get enough of a few types and try a few pairs of channels, and pick which you like if you can even hear a difference. you may or may not. but if you're just going to pick a cap and run with it (i'm assuming you're talking about the coupling caps in the audio path) the vishay BCs are not a bad cap, i'd maybe up the size to 470uf, and maybe the 105 degree series as well.