Tape Project Forum
Tape Machines => Tape Tech => Topic started by: Ki Choi on April 26, 2010, 04:14:21 PM
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The 5532 opamp is considered to be very low noise and good sounding opamp (as the opamps go..., I guess). It is used widely in Studer A810 and A820's (and other models as well) from tape head pre-preamp module in the headstack down the entire signal chain.
I was talking to a very knowledgeable studio person, and he thought finding a replacement opamp for 5532 would improve the sound drastically (but he couldn't remember the new opamp number...)
Any comments and suggestions would be much appreciated.
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Linear LT1469. Last time I checked they were about $9 each, and that was probably from Digi-Key.
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Yeah, I kinda researched the 5532 a while back. Some postings where folks were hating them dated way, way back and I had to wonder why manufacturers of some pretty high class gear were still using them.
One of the arguments (and the only one that stuck in my mind) was that guys that do a lot of multi tracking prefer the way they sound (or rather, they don't like the way other op amps sound) when the tracks are layered pretty thickly.
I could see how a sound that's real rich could get muddy pretty quickly if you overdubbed so maybe it's better to err on the lean side with some pro gear.
I don't know if that's the real reason but it did strike me as a consideration that end users might not consider.
Of course, that doesn't really apply to the 810/820 but a lot of water has gone under the op amp bridge since they were produced.
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Been there - done some of that.
The Burr Brown OPA2604 is pin for pin compatible and sounds better to me. Then there are the whole "new" series of products from National - among them the LM4562 and others just released - even better!
As Opamps have "improved", their distortion, current draw and perhaps most importantly offset voltages have gone way down. A lot of the pro machines used cascaded opamps with a number of reasonably large (5 - 10ufd) electrolytic coupling caps necessary between them to isolate offset voltages - which otherwise could get "multiplied" by amplifying devices further down the chain. If you have the ability and time you could go through the tape electronics, replace the older op amps with new and potentially eliminate a number of those caps - which probably affect the sound more than anything.
If you want to go numb or into overload quickly - peruse some of the websites like DIYaudio.com and search for "best opamps".
Better yet - don't! Load a TP tape and relax with a ......
Charles
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Load a TP tape and relax with a ......
With a what??? With a what??? Charles???
Jay
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Thanks guys for your input.
After posting the question, I thought to myself - I may have opened a can of worms - talking about replacing opamps...
The audio section of A810 and A820 have (from my memory - that's fading fast) five 5532s in Record Amp, four in Repro Amp, three in Line Amp, and one in Repro pre-amp, etc. So, it would take at least 26 new-and-improved opamps per machine... I guess it's relatively low cost for obtaining any improvement in pure audiophile (madness) terms... but made me think about the cost and benefits aspect.
I think Chalres meant for me to stop pondering about the opamps and chill with a cup of Starbucks (yes, it's raining in Seattle) or was it supposed to be a glass of stiff one?
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Hello,
One approach is to consider the discrete opamps made by Burson Audio. These are circuit boards made from individual transistors, caps and resistors made to fit where the IC plugs in.
Regards, Ken
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I would suggest that if one is going to change to op amps without other changes to the circuit that they consider the operating point that the original chip is running at. The chip I recommended is an actual drop in replacement, that is looking for the same range of op points as a 5532. Other op amps may want different operating conditions to sound their best.
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Hello Ki,
I agree with Stellavox that the best resuts could be achieved if along with the opamp upgrade you would be able to reduce the values of the so many 47uF L'ytics so that you can fit film caps inthere. I am still contemplating around that (lost in calculations). So far I have successfully used AD8066 (with smd adaptors) in several A810 machines and RevoxPR99. Those are for me the best cost-effective replacements.
Let us know how it goes,
Tod
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Close Jay and Ki - I was thinking about a cold drink / or warm companion / or both...
Or then again maybe "silence" and contemplation.... How do you folks listen / connect ???...
Somewhat OT - I'm hoping to take a trip cross country in July to "deliver" my daughter to a camp at Crater Lake OR, then take the rest of the time to work my way back East camping on "the Northern route". if this works out I'd like to visit some of you'se Pacific NW tapesters; enjoy a listen - and a cold one!
Charles
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Thanks guys for your input.
After posting the question, I thought to myself - I may have opened a can of worms - talking about replacing opamps...
The audio section of A810 and A820 have (from my memory - that's fading fast) five 5532s in Record Amp, four in Repro Amp, three in Line Amp, and one in Repro pre-amp, etc. So, it would take at least 26 new-and-improved opamps per machine... I guess it's relatively low cost for obtaining any improvement in pure audiophile (madness) terms... but made me think about the cost and benefits aspect.
I think Chalres meant for me to stop pondering about the opamps and chill with a cup of Starbucks (yes, it's raining in Seattle) or was it supposed to be a glass of stiff one?
Ki isn't always raining in Seattle??? LOL!!!
Jay
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Hi Tod,
Does AD8066 preserve vocal qualities of RC4559 in your testing? No other changes but IC swap? This is very good result a must try!
Best
ANdrew
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Hi Charles:
We have high concentration of tapeheads in NW area. You might need to allocate more than few days to visit all of us.
It would be great to have you visit my tape pasture and check out the herd - listen to choice TP tapes with some cold drinks I would provide. However, you will have to bring your own warm companion.
Ki
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Hi Dan,
Can I ask you what ICs you are using in the ATR 100 used to record the Tapeproject tapes? They sound great!
Regards
Francisco
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Hello Ki,
I agree with Stellavox that the best resuts could be achieved if along with the opamp upgrade you would be able to reduce the values of the so many 47uF L'ytics so that you can fit film caps inthere. I am still contemplating around that (lost in calculations). So far I have successfully used AD8066 (with smd adaptors) in several A810 machines and RevoxPR99. Those are for me the best cost-effective replacements.
Let us know how it goes,
Tod
Hi Tod:
thanks for your posts. From top of my head, I would associate the 47uF caps being mostly seen in the A80 audio cards but haven't spent too much time finding it in other models. The AD8066 is available only in surface mounting form in Digikey site. Let me know if you have more info on the SMD adaptors you had mentioned for A810.
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Hi Ki,
You can find information about the AD8066 and SMD sockets here:
http://www.soundlabsgroup.com.au/p/IC-Module-AD8066/IC+Module+AD8066
You should be very cautious using this IC - it has a very wide bandwidth and circuit layout and power supply decoupling can be critical, otherwise you can turn your board in an high frequency oscillator! I doubt that these precautions were taken in the layout of old tape recorder pcbs. The LT1469 seems more "stable".
Some time ago I had to design and build a ultra low noise, low drift preamplifier for the measurements of in the pA zone for a photodiode and it needed a lot of additional decoupling capacitors in the power supply.
Regards
Francisco
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Indeed, the AD8066 is wideband and may require the addition of a small cap (100p) in some cases. So far I have it on the preamp in the headblock and it works great, no tweaks needed. As the opamps are on sockets, it is easy to test the change and detect eventual oscillations.
Ki, there is a small forest of 47uF l'ytics (solid aluminium) on the signal path. If someone is qualified to calculate how low we can go there (10uf?) it will be a Major improvement to use film caps, at least WIMA or better (Siemens stacked polyester caps). Otherwise I use Nichicon NP with film bypass.
Andrew, the vocals sound amazing with the AD8066.
Tod
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Oh yeh 145MHz 180v/uS this is wide and high.
And it is not internally compensated so all those caramic 150pF/47pF caps will stay (PR99 just input board) or will have to added on other boards.
What is important is that it needs (datasheet) local PS decaupling and quite high 4u7 on each rail. If you missed that It will make it sound more pronouced and snappier and thinner, this AD chip has a tad of BB house sound. So that works for us in this case, but at the expense of distortions.
I went up to AD843 34MHz which likes ~2uF of decaupling and it makes substantial difference in distortions and percived fullness of sound just by ear.
AD843 is internally compensated so half what studer lists in comp. pF loops is good to keep it stable, (never had any problems here) and extends bandwidth over 100kHz. I settled on AD823/AD8610/AD843 mix across different boards. That RC4559 is a w@#e to sub.
AD8620/8610 was in your hands? It has a nerve and snap, quite close to RC but more refined.
Best
ANdrew
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I have used this opamp in a few projects. There were different versions from different manufacturers if I remember. The National Semiconductor NE5532-A was the special low noise version and spec'd out better then the Texas instrument piece. For what it's worth.
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Hi Crowner
Thanks for your info.
Is there a link for ap notes?
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That's way to much $ for a smd adapter. Look at the Brown Dog stuff, many varieties and attractive prices. Have used them for quite a few cases. http://cimarrontechnology.com/
The 5532 may be old but is still amazingly good, and very robust. The 5534 is better, but it is not unity gain stable.
For my money today, the LME series from National is a significant step forward in fidelity. There are things that have to be paid attention to in implementation, like it doesn't like very capacitive loads so may not be as useful in some applications. But it sounds great and is *very* quiet. It also has very low offset, allowing you to often change to the best cap ever, none. And they are unity gain stable.
Alan
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Hi Alan:
thanks for your expert comment on the 5532. I've come to the same conclusion that 5532 might be old but it is probably "good enough" for the R2R repro applications, and there are other areas for possible bigger sonic improvements.
Did a quick search on Mouser and Digikey sites and couldn't locate the National Semiconductor LME series Opamps. Can you tell us the source for the LME series Opamps?
Thanks,
Ki
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here is the link to the national semiconductor data pages, on there they have world wide stocking data, ie who's got what. (under the order tab)
<http://www.national.com/pf/LM/LME49720.html#Overview> this is the dual, comes in single and quad too, also a higher voltage version, LME4860 I think is the number.
Digikey has 1500 some odd and Arrow has 389, Arrow usually has better prices if you buy enough.
You can even get it in a TO99 can if you're willing to pay.
There is also a new TI/BurrBrown chip that is very good, but I don't know the number. 16something I think.
Alan
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Has there been any updates to preferable updates to the NE5532? The LME49720NA looks really good. The LM4562 seems like pretty much the same thing but without auto-shutdown, and the OPA2604 is quite similar but with a lower GBW (20Mhz vs 55Mhz).
Anyone with recent experience with these or other possible contenders in an A810/A820?
--Bill
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Bill,
I've done a LOT of work/listening with the LME 49xxx chips and they are fantastic. Can't tell the difference between most of them and the OP627's - and that is saying a lot
Charles
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Thanks Charles.
Is additional compensation for stability necessary or are they pretty much plug 'n play?
--Bill
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Bill,
There are maybe a dozen "new" chips - singles / duals / higher voltage (+/- 22V) versions and they come in different package styles. Only a few like the LME49710 (single) come in a DIP package and I think will directly replace the 5534 (do get that mixed up with the 32 which I believe is the dual). Some are available in an 8pin can which "purists" say is the best BUT is maybe 5 times more expensive. Regarding stability, I believe they are unity gain stable but please check the spec sheet. Have had to add a small compensating cap (200pf or so) between the output and inverting input on sopme designs but this may already be there if you are replacing op ampe in an existing circuit. Should look at the output with a scope after any new amp changeout to see if it is oscillating / stable.
Douglas Self still LOVES the 5532/4 and his evidence in his new low noise circuit book is pretty convincing. Also some great discussion of parts including capacitor selection.
Yea early Spring (here anyway) !!
Charles
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Charles, the LME49720NA is a dual inline package that will plug-in directly to the 5532 sockets in the Studer. The SOIC version which you could use with a SOIC->dip adapter, if desired, is the LME48720MA. There's even a TO-99 version, LME49720HA.
The app sheet has several circuit examples, including even, an NAB tape head preamp.
The 49720 has a little overshoot shown in a small-signal transient response graph, but no indication of large-signal transient response. Bandwidth and phase response are excellent, though. Looks like it might benefit with a little additional decoupling at the rails for each IC.
I do believe I'm going to try some of these.
--Bill
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Thanks Bill,
Good luck with your "play time", and be sure to look at the output with a scope.
To not tie up this thread with what others might consider minutiae, feel free to contact me - [email protected]
Charles
Forgot - a friend had problems with the tape pre circuit in the National app note