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pulsestudio
16-03-2009, 16:26
Hi all DIY bodgers
Can anyone suggest a pin compatible modern alternative to the TL072 with the following features: high slew rate/low noise/excellent CMRR , this is used as the line stage driver in an old pre-amp from the 80's, so good drive capability also a pre-requisite, any suggestions ? I had consdered either of the following: OPA2604 or LM4562 any comments about either or other suggestions for this appliication would be greatly appreciated.
cheers
Paul

leo
16-03-2009, 21:54
Just about anythings better than TLO72:)
LM4562's are decent but are not great at driving capacitive loads, OPA2604 should work ok anywhere, far from the best sounding IMO but cheap, OPA2134 or maybe OPA2132 worth a look too

The faster higher bandwidth types may cause problems depending on the circuit its used in

leo
16-03-2009, 22:02
Also OPA2107

pulsestudio
16-03-2009, 22:27
Cheers Leo, I use the AD825 in the outputs of my CDP, I auditioned many single op-amps for this and finally settled on the AD825 for its superb dynamics, scale and neutral presentation, the only problem being it is only available as a SMD device and spent ages soldering it to an 8 pin DIL socket, the Brown Dogs are too expensive, however they replaced the infamous NE5534, which is still a reasonable op-amp IMHO. I have looked to see if Analogue Devices make a dual version of the AD825 but it appears not, unless you know otherwise, as I would happily settle for a dual version in my pre-amp too :)
Thanks again for the alternatives selection you have put forward, I will check out the specs and availability, nice one ;)
Paul

leo
16-03-2009, 22:58
Yes, I'd imagine AD825's would better all those above, unfortunately I'm 90% sure there isn't a dual version.
One of my favourite duals is AD826, you have to be careful with these though, they have great drive but can go unstable in some circuits

pulsestudio
16-03-2009, 23:26
Woooow just checked out the AD826 datasheet, that is one fast device, 350V/uS ouch and 50MHz bandwidth, at only a fiver a throw, I'll order a couple anf try them, for a tenner it is worth the punt, cheers Leo, an even nicer one, although I see some bandwidth limiting may be in order by way of a cap in the feedback, we'll see, many thanks.
paul

FireFly
19-03-2009, 20:31
LT1469, LT1364, LT1361,......all three are way better than LM4562.
LT1469 is my current champ :eyebrows:

Alex Nikitin
21-03-2009, 13:59
Woooow just checked out the AD826 datasheet, that is one fast device, 350V/uS ouch and 50MHz bandwidth, at only a fiver a throw, I'll order a couple anf try them, for a tenner it is worth the punt, cheers Leo, an even nicer one, although I see some bandwidth limiting may be in order by way of a cap in the feedback, we'll see, many thanks.
paul

Paul,

be careful using AD826 as a replacement for TL072. Apart from a mentioned possible HF instability this device has very high (for an opamp) input currents - over 3 uA and that may be a problem if you replace a FET input TL072 with its pA range input currents (i.e. the difference is a million times!) . Easy and probably a trouble-free replacement would be another FET input device like OPA2132/OPA2134.

Alex

pulsestudio
21-03-2009, 22:16
Hi Alex

Thanks for the advanced warning, I have also noticed that the THD figures are not so good for audio applications, unfortunately I now have them from Farnell, however they are still in unopened packets so I wil return for either a couple of LT1469's or indeed the OPA2132/2134 as you suggest, thanks also FireFly for your suggested LT1469's, I have tried the single package version of this device in my AAA5 CDP and they did sound very open and dynamic, albeit with a little too much upper mid presence for my system and tastes, it is all good fun and quite a cheap way of adjusting to individual requirements though, cheers guys ;)

Paul

leo
21-03-2009, 22:48
Told you have to be careful ;) a circuit designed around a TLO72 may not take higher speed stuff, their sooooo slooow

What you using it in exactly? the opa2132/4 work in just about everything , I find them dark with softish bass, should be an improvement over the TL072's though and shouldn't cause any issues

Never tried the LT1469

pulsestudio
23-03-2009, 09:31
Hi Leo
Not tried the AD826 in circuit so I am not sure if it would be OK, just had second thoughts about it when I finally see the THD figures, they are not bad just not up there with some other well know devices.
The op-amp I want them to replace is in the buffer stage of an old Albarry DMP1 pre-amp, I think it is the line output driver to the power amp, I can't be 100% as I don't have the circuit but it is certainly near the tail end of the circuit, I have had suggested the NE5532 but these are quite slow by todays standards and do sound a little mediocre when compared to the AD825's, a tad too flat and less exciting IMHO.

leo
23-03-2009, 10:55
Yes, probably worth sending the AD826's back, just incase it causes problems in the circuit.

I personally do not like FET input based op-amps in a lot of circuits, they sound artificial to me, only places ok was regulation and only places they worked best was servo's

FireFly
28-03-2009, 11:57
agree with this review 110 % :)
http://www.head-fi.org/forums/f5/little-dot-mk1-opamp-rolling-304261/

Currently listening to Simple Minds, Dire Straits, Ace of Base, U2, Bruce Springsteen and Eric Clapton and LT1469 is my current champ for this music.

For Eurythmics, Blondie, Madonna, Ella Fitzgerald,...and listening to radio brodcast I prefer LT1364 over LT1469.

Primalsea
28-03-2009, 12:46
Some high speed opamps can oscillate and its not obvious unless you have a scope. If I remember correctly if you put a 10pF cap from the output to the - input it helps to quell the problem. Also the power rail decoupling caps my need upgrading. These go from as close as possible to the opamp power pins to earth and also across the +&- rails.

I first discovered this with some OPA2604's in a preamp section of an integrated amp. I turned the volume up, heard some radio skip and the zobel resisters melted as they become a dead short at high frequencies. Great amp though!! could whack out plenty of power at 1Mhz until I bandwidth limited it.

FireFly
31-03-2009, 12:53
yes, OPA2604 is prone to oscillations. As general rule, I use smallest cap to prevent oscillations, 3-5 pF or 1 cm of twisted insulated telephone wire (solid core) to create small capacitance.
LT1364 is far more stable than one mentioned above.

leo
05-04-2009, 14:54
I knocked up a differential to line out stage and currently trying out the LT1364, so far they sound ok

I did try the LT1462 but did not like those at all, they didn't handle complex music too well going too thick in the lower bass

pulsestudio
05-04-2009, 14:58
I knocked up a differential to line out stage and currently trying out the LT1364, so far they sound ok

I did try the LT1462 but did not like those at all, they didn't handle complex music too well going too thick in the lower bass

Nice one Leo, I will be very interested to learn of your evaluation of this chip, please post results ;)

just checked the data sheet on Farnell and it is one fast device 1000V/mSec, with good drive characteristics and low THD, could be the business for my line driver stage for the pre-amp, very interested to hear what you think after some burn in, and only £6.50 a pop, neat !!

cheers
Paul

FireFly
06-04-2009, 16:13
yes, LT1364 is very strong on vocals and mids + neutral highs.
Mix very well with "digital sounding sources" (dry, sterile, analitic,...sound).
Nor good for "tube sounding sources" (warm, dark, thick,...sound).

Naughty Nigel
26-12-2014, 23:39
Sorry to resurrect an old thread, but I thought I would see if there are any updates/new ideas on this subject?

I have a late model Quad 34 preamp that I bought from the devil's own internet auction site. This worked well enough for a few months (until it was too late to complain), but now the RH channel has died, and on opening it up it seems to have been seriously 'messed around with'. :(

The problem seems to be that one or more of the Op Amps has died, pulling the RH output down to just under - 3.5 volts! This I suspect may have been caused by the indiscriminate removal of coupling capacitors.

However, tracing through with a 'scope the RH signal disappears after the balance control. The voltage on the output of the balance control pot is about - 90 mV, so it seems there may be two or three inter-related problems, and possibly two or three Op Amps which need to be replaced - which brings me back to the question of which chips to use.

The preamp is currently fitted with OPA227P Op Amps, which I don't believe are original, and given the quality of work that I have found I would be doubtful that they are the best choice in any case.

Whilst on this subject, I wondered whether anyone could comment on possible replacements for the MM74HC4066N solid state switches used in these prepamps as I believe there may be better alternatives available now.

istari_knight
27-12-2014, 12:33
Best look out the classic section over on PFM Nigel, there's at least a couple of Quad restorers posting there :thumbsup:

Naughty Nigel
27-12-2014, 16:53
Best look out the classic section over on PFM Nigel, there's at least a couple of Quad restorers posting there :thumbsup:

Thanks James. But what is PFM?

I have done a couple of searches but there is nothing obvious.

Should I try the Analogue Art here?

Nigel.

Naughty Nigel
27-12-2014, 16:57
Thanks James. But what is PFM?

I have done a couple of searches but there is nothing obvious.

Should I try the Analogue Art here?

Nigel.

Sorry, found it now! :)