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Allen And Heath System 8 Modifications
Old 28th October 2011 | Show parent
  #121
Lives for gear
 
2N1305's Avatar
 

hey NoHatNoSwim:
that's a super looking place! I reall ylike the lighting and piano. Your desk, albeit really old, looks so modern the way you set it up! Is this in your basement?

wicked, I love shots of studios that look like this. I makes you want to work there.
Old 29th October 2011 | Show parent
  #122
Best thing to do, is do it all at once.
Come up with a plan, have everything together, and go for it.
The AD8512 are very nice and clean. Work well in this set up. Bigger caps help too. The buss bars just plain suck and are a hassle.
Good luck to you!
Your studio looks awesome!
Quote:
Originally Posted by NoHatNoSwim View Post
@ The Convicted !
if you did what I think you did with your desk - that is incredible !!!! Lol ! Cracked me up - super job. You did turn the main desk into a standalone EX8 on steroids by the looks of things ;p

I'm sooooo delighted I found this thread. Bought my Mk1 24:8:2 about 3-4 years ago. Since then, I've dreamed about modding it.

I use the desk reguarly, so downtime is a big thing for me. I had thought about pulling a few channels at a time, and working on them, but by the looks of it those rails and some other soldering makes pulling out and putting in channels a complete pain in the ass.

I have an electronic engineer who does fixes for me - so I'll be illiciting help from him as we've talked about working on this desk for a few years now.

He recently recapped the Power Supply for me, so that's one thing out of the way.

I also re-did the VU lights, as all mine were out. Interestingly, they seem to be grouped into 2 groups - 1,3,5,7,MasterL on one group and the others together. It turned out that one dodgy bulb on a group, disabled the whole group so if your lights are out, it may be only 2 bulbs that are causing all 10 to be out !

Excellent - this is on.........great stuff guys - I feel like I'm falling in love with this desk again and am inspired to stop making music altogether and get the soldering Iron out lol........hang on a second,....that's not right ?!!!

But seriously, I need to figure out how to do this bit by bit, without taking the desk completely out of action for a long time.......The connector mod looks like a 50/50 thing here - and my god that would make my plan work easier, but hmmmm....more noise ?!!!

Great stuff guys - wonderful to see - made my day this has.....

Al.

Here's my desk in the old studio (just moved into a new space a few weeks ago - glamour shots on the way soon).


https://www.gearslutz.com/board/attac...-desktop-4.jpg
Old 29th October 2011 | Show parent
  #123
ITS up for sale in the Classifieds, if interested.
Old 29th October 2011 | Show parent
  #124
Gear Maniac
 
neil.johnson's Avatar
Umm, if I'm not mistaken you have a Mk I as I can't see the EQ bypass switches up next to the HF switch.
Old 30th October 2011 | Show parent
  #125
Its an MKII, EQ Bypass is there.
Old 30th October 2011 | Show parent
  #126
Gear Addict
 

Are you sure? on the channels you sent me there's no bypass switch. I have a mk2 w/ eq bypass switches, but the mk1 channel should work fine
Old 30th October 2011 | Show parent
  #127
Quote:
Originally Posted by MrMegaEli View Post
Are you sure? on the channels you sent me there's no bypass switch. I have a mk2 w/ eq bypass switches, but the mk1 channel should work fine
Hmm, I guess I was wrong!
I was thinking of my dynamix board, it has the EQ bypass.
Old 1st November 2011 | Show parent
  #128
Gear Nut
 

Quote:
Originally Posted by 2N1305 View Post
hey NoHatNoSwim:
that's a super looking place! I reall ylike the lighting and piano. Your desk, albeit really old, looks so modern the way you set it up! Is this in your basement?

wicked, I love shots of studios that look like this. I makes you want to work there.
Thanks ;-) It's been evolving over the years - and I've been getting better at building desks / furniture too ;p

The last studio was in the sitting room of the house we were renting !

Lighting is absolutely Key to the mood in the room, and ergonomics are hugely important aswell to inspiring you to work - so I pay a lot of attention to that ;-)

New pics of the new place will be up soon - but here's a taster photo from my phone during a session we did this past weekend ! The new studio is set up in the upstairs of a 200 year old barn.
Attached Thumbnails
Allen And Heath System 8 Modifications-newstudiosetupcompositephoneshot-1.jpg  
Old 1st November 2011 | Show parent
  #129
Gear Nut
 

Quote:
Originally Posted by The Convicted View Post
Best thing to do, is do it all at once.
Come up with a plan, have everything together, and go for it.
The AD8512 are very nice and clean. Work well in this set up. Bigger caps help too. The buss bars just plain suck and are a hassle.
Good luck to you!
Your studio looks awesome!
Hey Convicted !

Wow - one go - sounds like downtime central !

How many IC's are there per channel ?

Is it a case of literally snipping the bus bars and then resoldering them once everything goes back in ? Leaving 8 strip pieces of bus bar attached to each channel and then 8 solders to get them back in ?

Also, that custom 8 channel you made has me very interested - did you do anything to channels 3 - 8 ? When you say they have direct outs, where did you wire them up to - the bottom row ?

Al.
Old 1st November 2011 | Show parent
  #130
Lives for gear
 

I've got a lot of AD8512 as well as other quality op amps left over from all my modding projecs for sale, anyone interested shoot me a PM.
Old 7th November 2011 | Show parent
  #131
Gear Nut
 

Cool !

Did I also see someone saying they had spare parts sitting around for this desk - might have been from the Convicted's hacked desk (by parts I mean knobs and caps etc).
Old 7th November 2011 | Show parent
  #132
There were already direct outputs, but I had to relocate them to the buss outputs, I think. Channels 3-8 I left stock but recapped and cleaned the pots.
I had some channels that were not working at first, but I found that I missed a few solder joints on the buss bars. Now they work perfect.
There are 3 ICs per input. The bussing I cant remember, but I think it was there as well. The master had 12 I beleive.
You sould snip the buss barr in sections like that, but I removed all the bussbarrs and ran newtinned copper wire originally.
Quote:
Originally Posted by NoHatNoSwim View Post
Hey Convicted !

Wow - one go - sounds like downtime central !

How many IC's are there per channel ?

Is it a case of literally snipping the bus bars and then resoldering them once everything goes back in ? Leaving 8 strip pieces of bus bar attached to each channel and then 8 solders to get them back in ?

Also, that custom 8 channel you made has me very interested - did you do anything to channels 3 - 8 ? When you say they have direct outs, where did you wire them up to - the bottom row ?

Al.
Old 6th March 2012 | Show parent
  #133
Gear Nut
 

Hi All !

A few months of silence in here - so I thought I'd update on what I've been up to.

My Desk : I have a 24:8:2 MK1

So, I'm currently in the middle of a full re-cap.

I've replaced caps as follows:

10uF 16v -> 47uF 16v
47uF 25v -> 100uF 25v
27uF 50v -> 82uF 50v
100uF 25v -> 220uF 25v
220uF 10v -> 470uF 10v

All caps are panasonic FC's.

I've actually been able to do all this recapping without cutting the bus bars !

I've figured out a way of doing it and getting in there without the need.

I did have to take the sides off and the centre support bracket bar at the master channel out to get access to Channels 1, Buss8, and the Master L.

Overall I'm really enjoying this right now. I'll have the capping completed by Thursday this week, so labour only will have taken me about 30-40 hours for.

I also have some OP amps for the channel 1&2, master L&R, and bus 1&2 - so that I can see what the difference is before making final opamp selection.

I've decided (with the aid and guidance of my engineer who I can't praise enough for his help and knowledge ) to replace IC1 & 2, but leave IC3.

We're focusing on the input circut, and once the OPAmps IC1's are done, there's also a transistor mod happening aswell. All working on the Inputs.

I'm not planning on going as far as the resistor changes , and don't plan to at all either.

On the Mark 1, the IC1 chip actually covers not only the input, but also the High, and Bass of the EQ. IC2 is fully dedicated to the Mid EQ, IC3 is at the fader end of the board where it seems to be at minimal impact so the decision is to leave 3 where it is, and replace the other 2.

Then, there is a final mod that we have planned. We're going to install switchable transformer outputs on the master bus. We've picked 2 smallish transformers with a view to seeing how they saturate. That will be a bit of an experiment, but could result in something quite special if we manage to get something that works well in there. Thus, it's switchable until the switch needs to be left on full time ;-)

So that's me,.........enjoying the hell out of this and really looking forward to finishing the caps, and getting the desk back in there asap to start doing some AB's on mixes, versus mixes from a few weeks ago, and then also A:B'ing the Recap&OpAmp channels versus the RecapOnly channels.

Then, finish OP Amps completely, and Transistors,

Then, transformers,

Bedtime, solder will be ready in the morning ;-)

~:Al:~
Old 6th March 2012 | Show parent
  #134
Gear Maniac
 
neil.johnson's Avatar
Quote:
Originally Posted by NoHatNoSwim View Post
Hi All !

A few months of silence in here - so I thought I'd update on what I've been up to.
Thanks!

For those folllowing along, schematics are available on the AHB support page for the System8:

System 8 | ALLEN & HEATH // WORLD CLASS MIXING

Quote:
Originally Posted by NoHatNoSwim View Post
My Desk : I have a 24:8:2 MK1

So, I'm currently in the middle of a full re-cap.

I've replaced caps as follows:

10uF 16v -> 47uF 16v
47uF 25v -> 100uF 25v
27uF 50v -> 82uF 50v
100uF 25v -> 220uF 25v
220uF 10v -> 470uF 10v

All caps are panasonic FC's.
I think you mean "47uF 50V -> 82uF 50V"

Also, the 47/50 caps on the mic input are rather close to the rated voltage when phantom power (48V) is turned on. I'm going to use 63V rated caps here on my Mk.II.

Quote:
Originally Posted by NoHatNoSwim View Post
I've actually been able to do all this recapping without cutting the bus bars !
Are you a key-hole surgeon by any chance?

Quote:
Originally Posted by NoHatNoSwim View Post
I also have some OP amps for the channel 1&2, master L&R, and bus 1&2 - so that I can see what the difference is before making final opamp selection.

I've decided (with the aid and guidance of my engineer who I can't praise enough for his help and knowledge ) to replace IC1 & 2, but leave IC3.
I think on the input channels the only choice is to go with FET op-amps without recourse to major circuit redesign. I plan on using OPA2134, which has less than half the noise voltage of the TL072 without going to above $2.

Quote:
Originally Posted by NoHatNoSwim View Post
We're focusing on the input circut, and once the OPAmps IC1's are done, there's also a transistor mod happening aswell. All working on the Inputs.
I'm interested in your transistor mod. I looked at using Toshiba ones (forget the part now), but the different pinout would mean some leggy gymnastics unless there was significant benefit.

Quote:
Originally Posted by NoHatNoSwim View Post
I'm not planning on going as far as the resistor changes , and don't plan to at all either.
That's something I plan on investigating. I've got an audio analyser so I'll be able to take some real measurements, together with some SPICE analysis to get an estimate of any benefits of resistor value changes.

Although I would suggest upgrading the mic input phantom power resistors to a tighter tolerance - 2% is a bit sloppy these days.

Quote:
Originally Posted by NoHatNoSwim View Post
On the Mark 1, the IC1 chip actually covers not only the input, but also the High, and Bass of the EQ. IC2 is fully dedicated to the Mid EQ, IC3 is at the fader end of the board where it seems to be at minimal impact so the decision is to leave 3 where it is, and replace the other 2.
Actually, I'd say the opposite: IC1 in the pre-amp is just acting as a buffer, no gain (that's handled by the transistors). The op-amps in the EQ are surrounded by filter capacitors, so again a so-so op-amp like the TL072 can do reasonably well here. The op-amp driving the peak LED is non-critical. Leaving the 2nd half of IC3 in the role of post-fade amp with a gain of 10dB. THAT, IMHO, is the critical op-amp in this design.

But I'm happy to be corrected!

Quote:
Originally Posted by NoHatNoSwim View Post
Then, there is a final mod that we have planned. We're going to install switchable transformer outputs on the master bus. We've picked 2 smallish transformers with a view to seeing how they saturate. That will be a bit of an experiment, but could result in something quite special if we manage to get something that works well in there. Thus, it's switchable until the switch needs to be left on full time ;-)
Make sure its a big switch, preferably a rotary. With a large black bakelite knob, that makes a nice clunk sound when switched. And don't forget the mad-scientist cackling sound whenever you need to "srow zee svitch Igor!"....

Quote:
Originally Posted by NoHatNoSwim View Post
So that's me,.........enjoying the hell out of this and really looking forward to finishing the caps, and getting the desk back in there asap to start doing some AB's on mixes, versus mixes from a few weeks ago, and then also A:B'ing the Recap&OpAmp channels versus the RecapOnly channels.

Then, finish OP Amps completely, and Transistors,

Then, transformers,
Fun times ahead!

Quote:
Originally Posted by NoHatNoSwim View Post
Bedtime, solder will be ready in the morning ;-)
Sweet dreams!

Cheers,
Neil
Old 29th April 2012 | Show parent
  #135
Here for the gear
 

I just bought a System 8 mark 3. Very interested in hearing about the mods you guys have done. Can you comment on the overall sonic improvements these mods made?

Also, with the mark 3, how much of a task would it be to convert the VUs to read the direct outputs on 1-16 as opposed to the tape returns?
Old 3rd May 2013
  #136
Gear Head
 

Hey everyone, I have a System 8 mark II 16x8 board that I've had for about 10 years. I really like it and it suits my purposes. My pots have gotten 'really' scratchy, esp the monitor volume control, so I have to tend to it.
I bought this from a really cool dude in Houston who was the original owner. It's in really good shape, but needs attention. My buddy tells me that leaky and old caps can be responisble for what we think are scratchy pots. In any case, I'm ready to embark on an restoration project, and possibly throw in some upgrading too. I have at least two sticky meters, and all the lights are out. I want to go LED (but with an incandescent color temp).

I'm really glad I found this thread, because I will surely need some help. I'm very interested in any tips and tricks you've learned along the way, and am happy posting my progress. I would like to have everything done by September or sooner.
Old 11th June 2013 | Show parent
  #137
Gear Nut
 

Quote:
Originally Posted by tvanderbrook View Post
Hey everyone, I have a System 8 mark II 16x8 board that I've had for about 10 years. I really like it and it suits my purposes. My pots have gotten 'really' scratchy, esp the monitor volume control, so I have to tend to it.
I bought this from a really cool dude in Houston who was the original owner. It's in really good shape, but needs attention. My buddy tells me that leaky and old caps can be responisble for what we think are scratchy pots. In any case, I'm ready to embark on an restoration project, and possibly throw in some upgrading too. I have at least two sticky meters, and all the lights are out. I want to go LED (but with an incandescent color temp).

I'm really glad I found this thread, because I will surely need some help. I'm very interested in any tips and tricks you've learned along the way, and am happy posting my progress. I would like to have everything done by September or sooner.
Hi There !

I dont think caps can cause scratchy pots - thats just scratchy pots. Try working them and see what happens. By working, that could mean 50 full turns side to side but that may rescue some of them - works for me !

The bulbs are wires in series so its quite possible that only 2 of them are gone. If you blew say 7 and 8, then non would work. If you blew only 7, then 1, 3 and 5 would also be gone.

Ive actually got a mix of original bulb and led installed. theres no doubt the bulbs look warmer than the leds - im considering getting the replacement bulbs and a few spares and reinstalling full bulbs.

Im also thinking of getting some more vu meters so as to make a monster vu panel for all channels aswell lol

First thing you should do is recap. They are early 80's so the caps are ready to come out at this stage. I did mine and then havent moddes since. Next up I have fairchild transistors ready to go into it :-)
Old 14th May 2017 | Show parent
  #138
Here for the gear
 

[QUOTE=NoHatNoSwim;7637927]

10uF 16v -> 47uF 16v
47uF 25v -> 100uF 25v
27uF 50v -> 82uF 50v
100uF 25v -> 220uF 25v
220uF 10v -> 470uF 10v

Are these value upgrades worthwhile?
Recapping the console now and need to order parts.
Any other suggestions?

(Oops meant to start new topic)
Your knowledge is much appreciated
Thank you.

Last edited by AS74; 14th May 2017 at 02:55 PM.. Reason: Meant to start new topic.
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