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Author Topic: IC upgrades  (Read 6296 times)

Danrisen

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IC upgrades
« on: August 14, 2010, 10:30:09 PM »

Has anyone found a pin to pin IC upgrade for the LM301's and the LF356 in the 462 eq's?

Also, when recapping these eq's what caps need replaced?  Just the 4 Panasonic on the 4-111 boards?


Thanks
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Warren Beck

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Re: IC upgrades
« Reply #1 on: August 15, 2010, 03:29:48 PM »

Hello.

Why re-cap them?  Have the caps blown?

LM301 are still available, The LF356 are more challenging to locate - http://www.taydaelectronics.com/servlet/the-291/LF356N-LF356-356-IC/Detail
Some have gone to a Burr Brown op-amps with the belief that they improve the circuit.  HOWEVER if you up-grade the op-amps you will definitely experience a lower noise floor from the units, as more modern manufacturing techniques has worked in our favour.

Regards,
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Regards,

Wb!

Anthony P. Kuzub

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Re: IC upgrades
« Reply #3 on: August 16, 2010, 02:43:36 AM »

I'm a total nut for recapping all electrolytics on anything with a serial number that starts with 89 or less  (I stock 22uf / 25V by the thousand) As I've shown in the past, these modules are (in some cases) on for 24 hours a day over a period of 10 years in tight spaces with little air moving around in them.  They do dry up.

It's less than 10 cents / cap...  I'll always gladly invest 60 cents per module for peace of mind.  As for the tantalum caps, they "almost never go" and if they do, replace as needed.. but a blanket of them is pointless as they don't ever dry up, they just fail.   

as for Opamps, the LF356 is a great alternative, and the OPA stuff is rather amazing as well.  One day I'll have to modify a whole "slew" of modules with different ICS and have a good listen.

Who's in?
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Tristan.Miller

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Re: IC upgrades
« Reply #4 on: August 21, 2010, 07:26:24 PM »

It's been a while since I've been inside the W/B toys...

When i was fixing up a bunch of modules, I dropped in TL071's in place of the single channel opamps that I suspected to be faulty... the pins are the same, minus 1,5 and 8... sometimes I would bend those pins up from the new IC, so that they didn't connect in the sockets.
the originals used them for frequency compensation, while the 071's used them to set the Off-Set...
(This is all from memory, so double check the pin-out if you try it!)

If the pin-out of a new op-amp lines up... it will work!


Also, while cleaning up a console filled with M480c's, one of the channels had a blown Pre-Amp...  one of the transistors went dead.
I didn't have a direct replacement, so I put in a Low-Noise BC549...  I built my "the british Ward-Beck" clones out of them...

The channel worked... and at max gain, with the fader all the way up... it was more than 4 times quieter than the stock channel strips!
I'm talking about very little Hiss and Pops and Crackling!

I couldn't leave one channel that clean... so I ended up replacing every preamp transistor in every other channel!

Did it affect the tone?  I didn't really test... I told the owner what I did, and to let me know what he thought...
The only word back I got was: 'These pre's sound f-ing sick!'

I remember a post somewhere on Geoff Tanner's forum... I think he put up a story, where the owner of a "the british Ward-Beck" console asked him if he did a phase-check on the entire console...
His response to the guy was 'Does it sound good?'
'Well, yea.'
'Then use it!'

And thats my rant!  Time for an other pint!
(You know I'm in a good mood when I ramble!)
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Danrisen

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Re: IC upgrades
« Reply #5 on: August 22, 2010, 11:22:57 AM »

Ok, so the moral of the story so far... no one has a direct IC upgrade for these babies.  I know the design is amazing and I thought with the advances in IC design over the years we would have been able to find a straight chip upgrade.  Let me know if there is a straight chip to chip or if the daughter board things turns into anything. 

Thanks
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Tristan.Miller

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Re: IC upgrades
« Reply #6 on: August 23, 2010, 09:20:46 AM »

301, 356, TL071, NE5534, OPA627, 741's....  All are single-amplifier opamps.
and that's just naming a few.
(That OPA-627 is a $20 opamp...!!!!  I kind of want to try one now....)

Look at the data-sheets of opamps for the Pin-Outs.... if it looks something like this:
"http://www.bitsbox.co.uk/images/ebaypics/741opamp.jpg"

then it will work.

It will fit into the same socket, and it will all amplify/operate/filter/do what ever the originals do.

The only thing to watch out for, are pins 1, 5, and 8.  Some single channel op-amps use them for internal frequency compensation, of off-set level calibration, or nothing.

If those pins cause problems, just break them off of the new IC's, as those functions are most likely not needed.
new IC's are usually compensated internally,  and the design of this era of WB gear doesn't care too much about a little bit of DC Off-Set.



Will it be an upgrade?  That is up to you to decide.

But there are hundreds of possibilities for you to try out.
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Tristan.Miller

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Re: IC upgrades
« Reply #7 on: August 23, 2010, 09:22:57 AM »

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Danrisen

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Re: IC upgrades
« Reply #8 on: August 23, 2010, 04:45:38 PM »

Tristan how would an OPA604 work?   They seem a little cheaper then the OPA627?  Anyone tried those?  I would try them but I don't have a desoldering iron yet so its not gonna be very easy to test them out.  I want to socket them and just rebuild them all. 

Tony have you tried the OPA604? 
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Danrisen

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Re: IC upgrades
« Reply #9 on: August 23, 2010, 11:19:35 PM »

the OPA604 looks pretty similar.

PIN1 is Offset trim
PIN2 is -IN
PIN3 is +IN
PIN4 is -VS (this is different, you sheet said VEE)
PIN5 is Offset trim
PIN6 is OUTPUT
PIN7 is +VS (this is different, you sheet said VCC)
PIN8 is NO INTERNAL CONNECTION

It is also unity gain stable.  Not sure if that is helpful or not.
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Tristan.Miller

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Re: IC upgrades
« Reply #10 on: August 24, 2010, 06:15:15 AM »

Just different labels.

VEE means the negative voltage supply.
-Vs means the negative voltage supply.

VCC means the positive voltage supply.
+VS means the positive voltage supply.

It's that simple.  All op-amps do the same thing... they just do it differently, which gives them different characteristics.
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Danrisen

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Re: IC upgrades
« Reply #11 on: August 24, 2010, 07:01:42 PM »

So a OPA604 should be a straight pin to pin upgrade then.  Is this correct?  I noticed on the 301an's datasheet it said:

Pin1 is Balance/Compensation
Pin5 is Balance
Pin8 is Compensation

So those are the same as Offset trim?  Or it doesn't matter either way because the OPA604 doesn't need balancing because it is internally balanced.  Sorry to ask so many questions.  I just am trying to learn a few things.

Thanks guys.
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Tristan.Miller

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Re: IC upgrades
« Reply #12 on: August 25, 2010, 07:20:51 AM »

Like I said a couple times earlier:

Only pins 1, 5, and 8 may cause problems.


Compensation/Balance was used on old op-amps to help stabilize the frequency response,
New op-amps have these circuits built inside of them, so they do not need to be Compensated or Balanced.

Newer op-amps usually have these pins labeled as Off-Set Trim.  This is used to add a constant DC voltage to the output of the amplifier.
This is something that is not needed in Ward-Beck amps.

You should be able to just put a new op-amp in.  The Compensation parts usually don't affect the off-set voltage.
But:
If it does cause problems, like if your new chip starts oscillating, or making weird tones or buzzes...
Then:
Remove the chip, bend pins 1, 5, and 8 upwards, so they don't connect to the circuit board, and put the new chip back in.


This is why it is always best to put in a Socket, if there is not one already there.

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Danrisen

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Re: IC upgrades
« Reply #13 on: August 25, 2010, 09:00:57 AM »

Thanks Tristan. I thought I understood you correctly but I just wanted to make sure.  Now the question is do I change the IC's on just the main board or do I change the IC's on the 4-126 daughter board as well?
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Tristan.Miller

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Re: IC upgrades
« Reply #14 on: August 26, 2010, 01:02:54 AM »

I'm not experienced with the 462...  but from looking at the schematic... i can tell you that it has a lot of chips!

The bulk of the signal passes through the main board... but the daughter board also processes the signal!

If you want to completely upgrade the module, you will have to change every chip...

but I think you should experiment!  Try just the main board in one, try the daughter board in another, and try everything in the next!


When I changed the IC's in some LA-4's, I changed the ones that the sound past through... and left the compression-processing ones alone.
The output is clear, without the normal dark-sound that you'd expect....
but the way that it compresses still has a dark vibe to it...


when you get into changing chips, it really is simply a matter of personal preference!
Don't follow someone else's suggestions just because they say it's amazing!
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