Wyn Palmer Phono Pre Build
- Thread starter mr_rye89
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All opamps, all used in the phono preamp. I opted to not use the preamp/buffer circuit (I don't think I need it). the first opamps are OPA1641AIDs, second set are OPA1611AIDRs, the DIP opamp is a TL052.
More details here: https://www.dropbox.com/sh/4iwr55ql8ynmfnx/AADX2-izp3fJig0ZrnkxcJwTa?dl=0
an there's a big Audiokarma thread too. you use different Opamps/resistors/capacitors depending on the gain you need.
More details here: https://www.dropbox.com/sh/4iwr55ql8ynmfnx/AADX2-izp3fJig0ZrnkxcJwTa?dl=0
an there's a big Audiokarma thread too. you use different Opamps/resistors/capacitors depending on the gain you need.
There are two versions one for MM and the other for MC. Rather than simply altering gain, the higher gain MM version uses parallel op amps to reduce distortion further. The entire circuit is optimized for the particular cartridge type.
The accuracy of the RIAA correction is about an order of magnitude better than 98% of the others out there. First time I saw the term mdB used…
The accuracy of the RIAA correction is about an order of magnitude better than 98% of the others out there. First time I saw the term mdB used…
From https://www.eenewseurope.com/en/op-...g-the-right-op-amp-jfet-input-types-reviewed/
The TL052 from Texas Instruments was designed to be an enhancement of the TL072, and so is naturally compared with it. Most of the improvements are in the DC specifications. The offset voltage is 0.65 mV typical, 1.5 mV max, compared with the TL072’s 3 mV typical, 10 mV max. It has half the bias current of the TL072. This is very praiseworthy, but rarely of much relevance to audio.
The distortion, however, is important, and this is worse rather than better. THD performance is rather disappointing at 19 nV/√Hz . As usual, practical distortion depends very much on how heavily the output is loaded, it deteriorates badly for loads of less than 4k7.
The slew rate is higher than for the TL072 (18 against 13 V/µs) but the lower figure is more than adequate for a full-range output at 20 kHz, so this enhancement is of limited interest. The power consumption is higher, typically 2.3 mA per op-amp section, which is almost twice that of the TL072. Like the TL072, the TL052 is relatively relaxed about supply-rail decoupling. At the time of writing (2009) the TL052 costs at least twice as much as the TL072.
The OPA2134 is a Burr-Brown product, the dual version of the OPA134. The manufacturer claims it has superior sound quality, due to its JFET input stage.
The input noise voltage is 8 nV/√Hz, better than half that of the TL052. The slew rate is typically ±20 V/µs, which is ample. The OPA2134 does not appear to be optimized for DC precision, but the typical offset voltage being ±1 mV, it is more consistent than the TL052, this is unusually good for audio work.
The OPA2134 does not show phase reversal anywhere in the common-mode range, which immediately marks it as superior to the TL052.
Just saying... This is why we use Texas Instruments SoundPlus™ OPA134 Series Audio Operational Amplifiers in our WOPLs.
The TL052 from Texas Instruments was designed to be an enhancement of the TL072, and so is naturally compared with it. Most of the improvements are in the DC specifications. The offset voltage is 0.65 mV typical, 1.5 mV max, compared with the TL072’s 3 mV typical, 10 mV max. It has half the bias current of the TL072. This is very praiseworthy, but rarely of much relevance to audio.
The distortion, however, is important, and this is worse rather than better. THD performance is rather disappointing at 19 nV/√Hz . As usual, practical distortion depends very much on how heavily the output is loaded, it deteriorates badly for loads of less than 4k7.
The slew rate is higher than for the TL072 (18 against 13 V/µs) but the lower figure is more than adequate for a full-range output at 20 kHz, so this enhancement is of limited interest. The power consumption is higher, typically 2.3 mA per op-amp section, which is almost twice that of the TL072. Like the TL072, the TL052 is relatively relaxed about supply-rail decoupling. At the time of writing (2009) the TL052 costs at least twice as much as the TL072.
The OPA2134 is a Burr-Brown product, the dual version of the OPA134. The manufacturer claims it has superior sound quality, due to its JFET input stage.
The input noise voltage is 8 nV/√Hz, better than half that of the TL052. The slew rate is typically ±20 V/µs, which is ample. The OPA2134 does not appear to be optimized for DC precision, but the typical offset voltage being ±1 mV, it is more consistent than the TL052, this is unusually good for audio work.
The OPA2134 does not show phase reversal anywhere in the common-mode range, which immediately marks it as superior to the TL052.
Just saying... This is why we use Texas Instruments SoundPlus™ OPA134 Series Audio Operational Amplifiers in our WOPLs.
If Wyn drops in you'll have to ask him why use the TL052 over an OPA2134 in this circuit, gotta be a reason......
EDIT: the TL052 seems to be in some kind of feedback loop with the OPA1611, the dropbox link has the skizmo.....
EDIT AGAIN: the TL052s are for DC feedback amps, whatever the hell that means...
https://audiokarma.org/forums/index...d-preamp-for-low-output-mc-cartridges.879145/
EDIT: the TL052 seems to be in some kind of feedback loop with the OPA1611, the dropbox link has the skizmo.....
EDIT AGAIN: the TL052s are for DC feedback amps, whatever the hell that means...
https://audiokarma.org/forums/index...d-preamp-for-low-output-mc-cartridges.879145/
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Looking for enclosures, the description of this one is real reassuring...
https://www.amazon.com/Aluminum-Enc...4716&sprefix=aluminum+amplif,aps,209&sr=8-101
https://www.amazon.com/Aluminum-Enc...4716&sprefix=aluminum+amplif,aps,209&sr=8-101
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I think this is the one I used for my phono preamp.
https://www.ebay.com/itm/3250861100...ghMdnSkybVnc6/1gi21w6xZDbBy4|tkp:BFBM9MfQ4pxj
I used the power button (new switch) and the right-most knob for the fine balance. Other knob is hidden under a quarter-inch of copper.
https://www.ebay.com/itm/3250861100...ghMdnSkybVnc6/1gi21w6xZDbBy4|tkp:BFBM9MfQ4pxj
I used the power button (new switch) and the right-most knob for the fine balance. Other knob is hidden under a quarter-inch of copper.
