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PostPosted: April 9th, 2017, 10:50 am 
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Joined: January 15th, 2015, 7:19 am
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Location: Baltimore MD
Maggies back in and Carvers shelved until OPA4227 chips come in to see if high pass musicality improves.
The maggies are more polite but much more musical.
laptop in foreground is RealRTA showing pink noise from 10 to 20khz


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PostPosted: April 9th, 2017, 12:09 pm 
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You might want to install a DIP socket so you can change back. On paper the the TLO74 is a much better performer. After looking at the data sheets I have to wonder why someone would recommend the the OPA4227. ??? :confusion-confused:

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PostPosted: April 9th, 2017, 4:14 pm 
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The OPA4227 is just an updated version of the OP27. It was a great OP Amp in its day and I built great MM and MC pre amps with the OP27 and OP37 a long time ago but there are better now. If you are looking at specs the LME49710 and LME49720 blow the OPA4227 away in almost every category. I am now using those in phono and line stages with great results.

Tom


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PostPosted: April 9th, 2017, 6:48 pm 
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My favorite audio op amps are the AD797 and LME49990. The AD797 can be hard to get stable depending on the circuit and the LME49990 isn't made any more. I don't believe there are any LME49990 available from an actual TI distributor. I'd be wary of sellers on eBay, especially if they happen to be located in China.


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PostPosted: April 9th, 2017, 6:58 pm 
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I'm using AD797s in my custom preamp. They work well but the new LME series have no problems with stability. If I were going to build it now I would use the LME.

Tom


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PostPosted: April 9th, 2017, 9:32 pm 
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Now I am confused. kits claims the OPA is an upgrade and charge a lot for the chips. I can get them much cheaper from Digikey, etc so that's why I got the stock TL's. So this must have been just marketing BS.
In stalled sockets when I built the boards so I can roll chips, but now I will not waste my time with the OPA , but do not have a clue of what to try


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PostPosted: April 10th, 2017, 1:33 pm 
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Bummer! I did some window shopping and the best Quad Op-amps for high-end audio are surface-mounted devices. Texas Instruments especially had some audio goodies that they inherited from Burr Brown when they bought out Burr Brown. They also are not cheap.

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PostPosted: April 10th, 2017, 1:56 pm 
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The following link may be of use for diy soldering of surface mount devices -

http://www.nutsvolts.com/magazine/artic ... _soldering


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PostPosted: April 10th, 2017, 3:43 pm 
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The problem here is that Paul's device(s) has quad op-amps in a dual-inline-plug (DIP) format. The DIP format, even though it has the same pin-out as the surface-mounted devices, is much larger.

I didn't do extensive shopping, but I did look at Analog Devices and Texas Instruments as my first go-to choices. There are numerous others such as Harris Semiconductor, Exar, Elantec, Signetics, National Semiconductor, etc.

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PostPosted: April 10th, 2017, 3:46 pm 
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SoundMods wrote:
The problem here is that Paul's device(s) has quad op-amps in a dual-inline-plug (DIP) format. The DIP format, even though it has the same pin-out as the surface-mounted devices, is much larger.


Adapters are available that you can solder the SMD to so it'll plug into the DIP socket....

Roscoe


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