TL072 swapping... yes this again

[Bang]

We have a Neotek Elite via 1988. Sounds great stock, lush and big. Swapped the main mix buss amps and monitor amps to BBs (various models). Sounds wider and opened up the top and bottom.

Now I'd like to go further. I've spoken to guys like Jim Williams who offered some things he would do to the console and that very well may be a route we will take. But I was wondering if you all could talk about chip swaps and power consumption with me for a bit.

The Neotek line input amps are TL072s. I want to change that to a faster, better sounding amp. The first we tried was the AD OP275 because it only draws one more milliamp then the TL072. But I don't like how it sounds, if we drive signal into the board kinda hot it acts weird, and the upper mids are kind of weird. Obviously you hear it more as you put it in more channels.

So I mix into only 16 channels of the board right now which to my ears is plenty to get the fat sound. It has the 800 watt power supply. Is there a TL072 swapper that might be ok to try that won't drain too much from the PSU? Like some LT amps? My other option is to get a new PSU and a new PSU distribution system from Neotek which is ofcourse big bucks. Since I like the sound of the board right now, I just want to see what improvement I can make without having to upgrade the PSU. I should also say that I don't use the auxes and only sometimes use the eq. The faders have 5532s.

[NeilTDeal]

Bang
I used to work for BB and am very familiar with their line of 72 replacements. I must say that all of their high performance opamps draw more power than the 72.(the old bias vs noise floor problem of a class AB output). I am not very sharp on Neotek consoles (the only one I ever saw was a short loaded demo board) but it would surprise me if they sized their supply near the console's nominal draw. With most consoles the supply is over sized with weakest link being filtering. Most of the consoles I have worked with can easily support more power draw from the summing amps if that is all you are swapping. The only time I had a problem was with a 16 bus soundcraft... I don't remember the model but it was new in 1987. Anyway, all that happened when we added the amps was that the rails (and therefore the whole console) got noisy.

[Bang]

If I put in 16 more power hungry BBs in the line ins, do you think the PSU will handle it? I'll obviously have our tech scope it, but even if things are fine in the scope, the PSU can burn out if the chips are drawing too much, right? Also, which BB would you recommend as a 72 replacement in a line input amp? Thanks

[NeilTDeal]

Originally Posted by Bang

If I put in 16 more power hungry BBs in the line ins, do you think the PSU will handle it?

Not knowing Neoteks I cant say but its easy to find out. Have your tech measure the current of both supply rails with all busses getting a 0db test tone. If it is under 70% of the rated power you have plenty of spare power for your summing amps.

Originally Posted by Bang

I'll obviously have our tech scope it, but even if things are fine in the scope, the PSU can burn out if the chips are drawing too much, right?

Again, it depends on the design of the power supply, but the only components that are typicaly taxed when you over-draw a brute-force supply are the transformer, the bridge rectifier and sometimes the voltage regulators. I say sometimes for the regulator because many regulator designs actually make the regulator work harder when little or no power is being drawn. However, my experience has been that the filtering caps pass audible ripple long before either of these components is stressed.

Originally Posted by Bang

Also, which BB would you recommend as a 72 replacement in a line input amp?

My favorite is still the OPA2604. Extremely low distortion, ultra low noise, and many say very musical sounding all the way up to just before it clips.

[Jim Williams]

Get;
"Optimizing Opamp Performance" by ex-BurrBrown designer Jerald Graeme.

This will help explain that smoke eminating from your gear.

The OPA2604 is NOT a direct replacement for a TL072.

Jim Williams
Audio Upgrades

[M@strongroom]

Not knowing Neoteks I cant say but its easy to find out. Have your tech measure the current of both supply rails with all busses getting a 0db test tone. If it is under 70% of the rated power you have plenty of spare power for your summing amps.

I'd say you need a lot more headroom than that. Obviously it depends what you'd describe as 0dB, but what you've got to consider is the transient when everything kicks together on the one... You need significantly more than 30% over 0VU...

And the first sign of a struggling power supply is not smoke or burning, but a struggle to reproduce the "oommph" in the bottom end.... Many people perceive it as lack of bass extension but it's actually the PSU bottoming out on the low end transients.

Mult up a Kick drum and Bass guitar playing tight on all 16 channels, and mix hot... Stick a meter across the power supply and look out for sagging.

My favorite is still the OPA2604. Extremely low distortion, ultra low noise, and many say very musical sounding all the way up to just before it clips.

As said before NOT a drop in for the TL072, but a good sounding amp if a little "soft". And the data sheet for it reads more like "audiophile weekly".

[David Kulka]

"Mult up a Kick drum and Bass guitar playing tight on all 16 channels, and mix hot... Stick a meter across the power supply and look out for sagging."

The power supply won't sag when the amplifiers that are hung off it run out of headroom. When op-amps reach the maximum output voltage (determined by the maximum specs of the device and/or the voltage of the supply) there is very little additional current demand.

The current that an opamp draws from its supply is the sum of its quiescent current and the small amount of power it delivers at a given time. Nothing special happens in terms of power supply demand as the maximum output level is approached.

To see whether an opamp circuit running out of headroom connect a scope to its output and see where the clipping point is. Generally you want to have at least 16 or 20 db of headroom over normal operating level. 20db is a 10:1 ratio, that's a lot more than 30%!

[alexstobbe]

Originally Posted by Jim Williams

Get;
"Optimizing Opamp Performance" by ex-BurrBrown designer Jerald Graeme.

This will help explain that smoke eminating from your gear.

The OPA2604 is NOT a direct replacement for a TL072.

Jim Williams
Audio Upgrades

What opamp do you recommend to replace the TL072 on the soundcraft 200B mixer.

What needs to be done if I choose to use the OPA2604.

I may purchase a couple of the following to hear how they sound:
OPA2604
OPA2134PA
OP275GP
OPA2132

Will I damage anything by straight swapping these?

I apologize if I am ignorant, I'm new to electronics.

Thanks so much!

[Jim Williams]

I just finished a 200B. I used mostly National LME49720 opamps. The groups and master are direct coupled, no capacitors in the signal path.

Many additional parts were required to make them work, local psu bypass caps, feedback phase compensation caps, rewiring the front end into trans-amps, etc. The rear of the pcb's now have lot's of parts stuck on them. It's not a plug and play design.

Jim Williams
Audio Upgrades

[alexstobbe]

Thanks so much for the reply!

Although I'd like to learn and try replacing the opamps myself, I think it makes more sense for me to leave my master section alone and send it to you to have LME49720 opamps installed. (based on my lack of experience)


I'm was planning on doing the following on all of my channel strips. (w/ sweepable mids)

Replacing the (2) 47uF/63v phantom blocking caps (C1, C2) with 2 100uF/63v Nichicon PW series.
Replacing the (2) 100uF/10v caps before the input gain pot (C3, C4) with 100uF/10v Nichicon PW series.
Replacing the Two 100uF/10v caps that are parallel (C9, C10) and attached to one leg of the trim pot with one 1000uF/10v Nichicon PW series.
Replacing the (3) 47uF/25v coupling caps (C15, C25, C29) with 220uF/35v Nichicon PW series.
Replacing the (4) 47uF/25v decoupling caps the power rails have (C16, C17, C30, C31), with 470uF/25v Panasonic FM series.
Replacing the fusing resistors (R22, R23, R61, R62) before the decoupling caps with 10 ohm, 1/2 watt 1% metal film resistors.

Should I continue with these replacements if I plan on replacing the TL072 opamps in the channels with National LME49720?

Maybe I'm better off to send you a channel strip as well. Do you mind if I send you one channel then copy it?
(shipping from Canada would not be fun for 24 channels)


I also realize that I will need to either get a new power supply or mod my existing one.

Am I best to call the number at Audio Upgrades to schedule a mod?

Thanks so much!

[dcollins]

Originally Posted by Bang

The Neotek line input amps are TL072s. I want to change that to a faster, better sounding amp.

I'm always curious where the idea that "faster" is related to "better sounding." When you look at the gear that is considered classic, the slew-rates can be measured with a calendar.

In blind tests the super slewing 3000V/us parts never fare well, and things like the 2520 with iirc, 5V/us always do better............

On that same idea, is there any highly-regarded record done with anything remotely fast?

Certainly not classic rock records.


DC

[Jim Williams]

Older Spectrasonics gear was pretty quick. The venerable Ampex ATR 102 used the LM318, a 70 v/us slew rate.

Speed of the circuit is only one factor. Sonic effects of passive components, amplifier THD, IMD, loop gain, etc, all have a place in evaluating a design.

A dirty fast opamp can be an ugly sounding thing. A clean one can be revealing.

Jim Williams
Audio Upgrades

[cathode]

Originally Posted by Jim Williams

Older Spectrasonics gear was pretty quick. The venerable Ampex ATR 102 used the LM318, a 70 v/us slew rate.

Speed of the circuit is only one factor. Sonic effects of passive components, amplifier THD, IMD, loop gain, etc, all have a place in evaluating a design.

A dirty fast opamp can be an ugly sounding thing. A clean one can be revealing.

Jim Williams
Audio Upgrades

Your examples of the ATR and Spectrasonics are well taken, Jim. No question that many fine recordings have been made on ATR's, but can you give us a list of superb sounding records done on Spectrasonics consoles? For that matter, with any consoles fitted with your tizzy, fast chips?

[Jim Williams]

I don't have time now to research all those but there are many.

A couple of rock CD's that do come to mind are 2 Yes albums produced by Billy Sherwood back in the late 1990s. This was right before Pro Tools ruined everything.

Billy had a small studio in Van Nuys by the airport. He was hired to produce a Yes CD but then was brought on as one of the band members. He had a Tascam M-600 console. It was rebuilt with all those fast "tizzy" opamps, EQ caps, etc. He tracked to a Sony APR-24 analog machine.

They loved the tracks they cut. None of the other band members saw one another, they all hate each other. Billy would record with them one at a time.

They went to the Enterprise to mix on the 80 input SSL with Ultimation moving faders, winged design, outboard forever and all that star trek stuff like the "beam up" sound when you entered.

The band bitched. They hated the SSL sound, even though they used them before. They couldn't get the punch and clarity they got on that piece of s**t lowly Tascam console loaded with all those "tizzy" opamps.

So they loaded up the car and moved to Tennesee. They rented all the outboard like 480's and mixed on that Tascam with those "tizzy" opamps.

You can hear the results yourself. The first CD is called "Open Your Eyes". It has the usual charactors, Jon Anderson (BTW, still sounds great today), Steve Howe, Chris Squire, Alan White and Billy. Kicks pretty good to me. You will also find Audio Upgrades at the top of the "special thanks" list on the inside credits.

Jim Williams
Audio Upgrades

[JohnRoberts]

Originally Posted by dcollins

I'm always curious where the idea that "faster" is related to "better sounding." When you look at the gear that is considered classic, the slew-rates can be measured with a calendar.

DC

"Faster" is code for newer. There have been adequately fast off the shelf opamps for a few decades now, and for the record the TL07x with 13v/usec is among those I consider adequately fast.

That said there are many newer parts in the decades since with better specs for other parameters like, lower input noise, stronger drive capability, etc.

As with any circuit it also depends on how used. There are probably some TL07x sockets where a modern upgrade can make an audible improvement, and others where it won't.

I appreciate that opinions vary, but if you do the math on 13v/usec it isn't slow in the context of audio. If you hear a difference I submit it is something other than speed.

JR

[Sugarnutz]

I'm a Spectrasonics guy here, have an old 1020 console, 3-band EQ, 101 cards. I always thought if I wuz gonna get a "Star Wars" automated console it would probably be a Euphonix CS3000. Aren't the CS2000 & CS3000 both chock full of TL072's?

[dcollins]

Originally Posted by JohnRoberts

I appreciate that opinions vary, but if you do the math on 13v/usec it isn't slow in the context of audio. If you hear a difference I submit it is something other than speed.

The maximum slew-rate of vinyl is something like 5V/us. I was incorrect about the 2520, the rated SR is actually 3V/us.


DC

[Aerophone]

Hi Jim.

I usually read that you consistently recommend lme49720 or lt1358's for duals. in what context do you usually prefer the LT's to the Nationals or vice-versa?

[Jim Williams]

It's all in the application and circuit design. There are several others I also use, some very new. Some have noise as low as a 300 ohm resistor, some are very fast like the 7000 v/us slew rates CFA's I used in the Mark Levensen DAC designs, some have -154db THD.

When a circuit is reworked here it's made so most of the contenders will work properly with stability. Machine sockets are installed. The User can play all day with the opamps if they like. I encourage that. It's your gear and you should be able to make it sound like you want.

Jim Williams
Audio Upgrades

[joe-electro]

Aerosmith's "Toys In The Attic" was tracked on a Spectra Sonics. Note that Spectrasonics (one word) is a different company and doesn't do old-school analog hardware.

Joe

Originally Posted by cathode

can you give us a list of superb sounding records done on Spectrasonics consoles?

[dcollins]

Originally Posted by joe-electro

Aerosmith's "Toys In The Attic" was tracked on a Spectra Sonics. Note that Spectrasonics (one word) is a different company and doesn't do old-school analog hardware.

You can't turn on the radio without hearing classic rock mixes made with TL072's.............


DC

[12Bass]

FWIW, I've found that the OPA827 (x2) is a good sounding FET replacement for the old TL072. It's more open sounding, but still warm and musical, IMO. I've found the TL072 to have a somewhat hazy/fuzzy coloration.

[joe-electro]

I think the TL072 is a good sounding chip as long as there aren't 20+ of them in the signal chain or the passive components around them are crap.

Joe

Originally Posted by 12Bass

FWIW, I've found that the OPA827 (x2) is a good sounding FET replacement for the old TL072. It's more open sounding, but still warm and musical, IMO. I've found the TL072 to have a somewhat hazy/fuzzy coloration.

[joe-electro]

True, although the SS board 'Toys In The Attic' was made on was most likely 100% discrete.

Joe

Originally Posted by dcollins

You can't turn on the radio without hearing classic rock mixes made with TL072's.............


DC

[Thee_Adleen]

Originally Posted by alexstobbe

Thanks so much for the reply!

Although I'd like to learn and try replacing the opamps myself, I think it makes more sense for me to leave my master section alone and send it to you to have LME49720 opamps installed. (based on my lack of experience)


I'm was planning on doing the following on all of my channel strips. (w/ sweepable mids)

Replacing the (2) 47uF/63v phantom blocking caps (C1, C2) with 2 100uF/63v Nichicon PW series.
Replacing the (2) 100uF/10v caps before the input gain pot (C3, C4) with 100uF/10v Nichicon PW series.
Replacing the Two 100uF/10v caps that are parallel (C9, C10) and attached to one leg of the trim pot with one 1000uF/10v Nichicon PW series.
Replacing the (3) 47uF/25v coupling caps (C15, C25, C29) with 220uF/35v Nichicon PW series.
Replacing the (4) 47uF/25v decoupling caps the power rails have (C16, C17, C30, C31), with 470uF/25v Panasonic FM series.
Replacing the fusing resistors (R22, R23, R61, R62) before the decoupling caps with 10 ohm, 1/2 watt 1% metal film resistors.

Should I continue with these replacements if I plan on replacing the TL072 opamps in the channels with National LME49720?

Maybe I'm better off to send you a channel strip as well. Do you mind if I send you one channel then copy it?
(shipping from Canada would not be fun for 24 channels)


I also realize that I will need to either get a new power supply or mod my existing one.

Am I best to call the number at Audio Upgrades to schedule a mod?

Thanks so much!

I am attempting to do the sweepable mids in my EV evt251. However I am having issues finding what component/s I need to modulate. Any advice?

[RogerFoote]

Originally Posted by Jim Williams

I don't have time now to research all those but there are many.

A couple of rock CD's that do come to mind are 2 Yes albums produced by Billy Sherwood back in the late 1990s. This was right before Pro Tools ruined everything.

Billy had a small studio in Van Nuys by the airport. He was hired to produce a Yes CD but then was brought on as one of the band members. He had a Tascam M-600 console. It was rebuilt with all those fast "tizzy" opamps, EQ caps, etc. He tracked to a Sony APR-24 analog machine.

They loved the tracks they cut. None of the other band members saw one another, they all hate each other. Billy would record with them one at a time.

They went to the Enterprise to mix on the 80 input SSL with Ultimation moving faders, winged design, outboard forever and all that star trek stuff like the "beam up" sound when you entered.

The band bitched. They hated the SSL sound, even though they used them before. They couldn't get the punch and clarity they got on that piece of s**t lowly Tascam console loaded with all those "tizzy" opamps.

So they loaded up the car and moved to Tennesee. They rented all the outboard like 480's and mixed on that Tascam with those "tizzy" opamps.

You can hear the results yourself. The first CD is called "Open Your Eyes". It has the usual charactors, Jon Anderson (BTW, still sounds great today), Steve Howe, Chris Squire, Alan White and Billy. Kicks pretty good to me. You will also find Audio Upgrades at the top of the "special thanks" list on the inside credits.

Jim Williams
Audio Upgrades

Thanks for that interesting story, Jim!
I love that album... Well, I love pretty much all Yes, but I have a special place for Billy Sherwood's contributions... Some cool stuff on the Chris/Billy Conspiracy CD, but more home studio sounding which is fine by me as well.

Anyway, the analogy the story makes speaks volumes!!!

Best
Roger

[Jim Williams]

If you post/link that EV schematic, it's probably a couple of resistors hanging off the dual sweep pot.

Thanks for the comments Roger. Those records sort of "evolved" as different stuff was tried. Billy was part player, part engineer, part producer and main shrink for the rest of the guys.

Whatever works, as they say (tizzy opamps included).

[kaiO]

I tried many chips. I think TL2072 is the best for direct replacement. I know it's a funny conclusion, but my ear told me that. (Not my head nor eyes reading the spec sheet), after I perform blind test. TL2072 still has that warm FET feel but much less cloudy.

LME4xxxx or boutique FET chips can be great (with proper mod), if you like the modernized sound, but are you looking for that sound?