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55xx vs TLO7x: forget Iraq lets have a chip war Other Modular Audio Processors
Old 6th February 2003
  #1
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sammygee's Avatar
 

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55xx vs TLO7x: forget Iraq lets have a chip war

A few years back when I found myself significantly more nomadic I noticed something about all the different consoles I was working on. They fell into two camps: ones that used the various TLOxx op amps vs those that used 553x chips. Time after time I found I much prefererred the sound of the 553x equipped desks the TLO boards. Essentially Neve, MCI vs Amek,Neotek,Trident. I brought this up with a friend of mine who had spent a lot of time behind Neoteks but also loved his 3m tape machines(M56) and was a bit of a builder of stuff for his personal and a few other folks use. He concurred. We both seemed to think that the 553x was more forgiving and that when pushed into distortion seemed to behave in more pleasing and less harsh fashion. The TLO equipped stuff on the other hand seemed to get clippy and really sharp sounding when pushed hard (trident especially) and that the eqs(Amek Apc 1000(their SSL killer-whoops), Neotek Series 2 vs mostly a Neve 8128) were much less grainy and cool sounding in the 553x neve. Even the owners of the amek(post full refurbishment) commented on how much more they like the sound of the neve eq. So tell me am I smoking crack? I know it is more complex than the chip alone but is there anything to it? I haven't been exposed to the analog devices "upgraded tlo" so is it the stock TIs. Anyone?
Old 7th February 2003
  #2
Smart Research
 

I'm with you....just forget TLOXX. Noisier, no faster, and unable to drive a wet paper bag. After 20+ odd years, still nothing has quite beaten the 5534 on all factors simultaneously. You can get an improvement in one or two factors, only with losses in others, and my guess is that it's the physics of chip construction, allied to interest from manufacturers to solve problems for more analogue audio sales. You will find lower noise chips, but with lower supply voltages. Higher slew rate chips, but with higher offset etc. etc.

So where too....the main thing to try to improve in the 5534 for me is slew rate. Unless you go wholly discrete, I feel for an opamp solution the OP275 combined with transistor outputs beats the 5534 on several fronts, though noise is still similar, (but better for higher source impedances). Start designing in critical areas like mic preamps though, and you must go to mostly discrete devices to still be in the running...though there is one (only !) opamp you can use to cancel output offsets and allow for dc-servo circuitry that doesnt thump..

Al.
Old 9th February 2003
  #3
Gear addict
 

Okay, I've been waiting for years to rechip my board. TL072's with the odd 5532 are the stock chips. Are you saying that just replacing the chips with OP275's nets nothing over the 5532's without transistors helping each stage? Maybe to up the ante on the TLO72 stages without increasing the current draw? (I'm going to upgrade the power supply regardless.)

I'm probably going to end up socketing a couple channels, taste testing, and repeating, but it'd probably help if I had a better clue what the hell I was doing instead of semi-randomly doing replacements, especially with the potential for oscillations. Where do I read up on using monolithics, from the basics?

Bear
Old 9th February 2003
  #4
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subspace's Avatar
Quote:
Originally posted by Gone Fission
Okay, I've been waiting for years to rechip my board. TL072's with the odd 5532 are the stock chips. Are you saying that just replacing the chips with OP275's nets nothing over the 5532's without transistors helping each stage? Maybe to up the ante on the TLO72 stages without increasing the current draw? (I'm going to upgrade the power supply regardless.)
You ain't askin' me, but I'll take a shot anyway. He's saying nothing really beats the 5532 on all fronts, but there are quite a few better performing chips in certain areas. So it's not as simple as what chip is better than a 5532, it's more what chip is the best compromise of attributes for a given application.

Quote:
Originally posted by Gone Fission
I'm probably going to end up socketing a couple channels, taste testing, and repeating, but it'd probably help if I had a better clue what the hell I was doing instead of semi-randomly doing replacements, especially with the potential for oscillations. Where do I read up on using monolithics, from the basics?

Bear
The manufacturer's data sheets are a good place to start, they've got plenty of applications notes with attached circuit diagrams. Since you're replacing TL072s and 5532s, I'd go to TI.com for the original's data sheets, and compare them to some of the Burr-Brown replacements available through them as well. Check out the my.TI feature to get yourself some free samples of the pricier B-B chips. HTH
Old 9th February 2003
  #5
Gear addict
 

I've already got some BB and Analog Devices samples. Anyone know if they monitor double dipping? If I could rechip with just freebies, it'd be pretty nice . . .

Bear
Old 10th February 2003
  #6
Smart Research
 

Quote:
Originally posted by subspace
nothing really beats the 5532 on all fronts, but there are quite a few better performing chips in certain areas. So it's not as simple as what chip is better than a 5532, it's more what chip is the best compromise of attributes for a given application.
spot on, though I would guess the OP275 would likely be better in spots not driving less than 1k ohms, and improve on all TL072's. The taste testing's the best way to go....(get a Hakko 474 desolder station first!) but I'd check all changed chip outputs liberally with a scope for signs of oscillation....patching/switching/power spikes may all cause it to start, or not till youve changed more than two channels worth, etc etc. so it can be intermittant, frustrating, and not immediately audible.

Seems we have two chip threads going....and theres good chip info appearing on both.....

Al.
Old 10th February 2003
  #7
Smart Research
 

Quote:
Originally posted by Gone Fission
I've already got some BB and Analog Devices samples. Anyone know if they monitor double dipping? If I could rechip with just freebies, it'd be pretty nice . . .

Bear
dont tell them I said so....

you could try asking each of the AD or BB distributors if they had a couple of samples in turn....but you could well spend more on the calls !

Anon.
Old 10th February 2003
  #8
Gear addict
 

Okay, how do I easily determine what load the chip is driving? The channel strips are on their own cards, accessed by flipping the mixer, taking off the bottom pannel, and removing the molex connectors. (A&H CMC series.) Do I need voltage in the circuit to determine the load? I should spring for the service manual, I suppose, in hopes that it might say, as well as giving me tips on troubleshooting the dead channel (16 of 16, not a problem yet with my 8 track machine).

Bear
Old 11th February 2003
  #9
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You're mainly concerned with the chips used as line drivers on the console's outputs. If they use a TL072 as an output driver for the insert sends or direct outs, you're just looking at the input impedence of the device you're plugging it into. Trying to drive a 600 ohm balanced input, like a Manley Vari-Mu, from a TL072 output stage is really driving uphill.
My Trident had TL071s driving every output in stock form, which wasn't really up to the task of driving wire, let alone a low impedence balanced input. I swapped all the output drivers with B-B OPA134s, and was alot happier with the desk's headroom and clarity. HTH
Old 12th February 2003
  #10
Smart Research
 

Yes, worry first about any chip connected to the patch or outputs. The circuits tell you everything else.......and a good scope.....and ideally an AP.....

I hadnt come across the OPA134, thanks !. Looking at the datasheet, being a fet opamp it looks definately like a good upgrade for TLOXX. Though, comparing with a 5534 the output drive is not as good, and noise will be worse in low impedance (<10k) input circuitry. You'd get better chip distortion, and double the slew rate though.

Al.
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