I'm looking at these options:
Hi-Fi RIAA Phono Preamp
(diagram inc.)
or this one:
RIAA PRO Correct Compensation Pre-Amplifier DIY Kit (Stereo) for Phono Turnable | eBay
(ad includes diagram)
or this:
Audio Stereo MM Phono RIAA Preamp Module, Kit, Based on OPA2134 SKU168005 | eBay
(diagram shown in ad)
or, don't laugh, this one:
Phono Preamp Pre Amp Amplifier 2inputs+ Volume Control | eBay
As you can tell, I'm looking for something low budget, but obviously I want the best sound possible
). I'm attracted to the last one as it's ready to go and is perhaps tweakable.. What do you think?
Hi-Fi RIAA Phono Preamp
(diagram inc.)
or this one:
RIAA PRO Correct Compensation Pre-Amplifier DIY Kit (Stereo) for Phono Turnable | eBay
(ad includes diagram)
or this:
Audio Stereo MM Phono RIAA Preamp Module, Kit, Based on OPA2134 SKU168005 | eBay
(diagram shown in ad)
or, don't laugh, this one:
Phono Preamp Pre Amp Amplifier 2inputs+ Volume Control | eBay
As you can tell, I'm looking for something low budget, but obviously I want the best sound possible
). I'm attracted to the last one as it's ready to go and is perhaps tweakable.. What do you think?
Hi,
I´d rather opt for the stage with the AD797.
The TL072 (Elliod) as well as the OPA2134 are too noisy in this application.
Also the resistance values in Elliods inputs stage are larger than it´d be good for a lownoise design. A 3-active-stages circuit like the OPA2134-circuit is unnecessary for phono-MM.
The AD797 is one of the best OPamps You could choose for a MM-input stage.
jauu
Calvin
I´d rather opt for the stage with the AD797.
The TL072 (Elliod) as well as the OPA2134 are too noisy in this application.
Also the resistance values in Elliods inputs stage are larger than it´d be good for a lownoise design. A 3-active-stages circuit like the OPA2134-circuit is unnecessary for phono-MM.
The AD797 is one of the best OPamps You could choose for a MM-input stage.
jauu
Calvin
what kind of cartridge will you be using?
generally speaking, listening with cartridges attached, you will hear lower noise with a JFET input op amp (like OPA627) for MM and with a bipolar transistor input opamp (like AD797) for MC.
btw, rod's design is fine; just replace the TL072 with a "better" part.
mlloyd1
generally speaking, listening with cartridges attached, you will hear lower noise with a JFET input op amp (like OPA627) for MM and with a bipolar transistor input opamp (like AD797) for MC.
btw, rod's design is fine; just replace the TL072 with a "better" part.
mlloyd1
Hi,
generally speaking, one couldn´t claim which is better here noisewise, JFET or bipolar. It depends on the circumstances.
Generally one can only say that JFETs show lower noisecurrent values -which dominate with high source impedances and bipolars show lower voltagenoise that dominates with lower source impedances.
The problem with MMs is that they are somewhere just on the edge.
Loaded with 47kOhms and a couple of pFs the source impedance the OPamp input ´sees´ will be around 1kOhm starting at dc and rising over ~5kOhms at 1kHz to maybe 30kohms at 20kHz. AFAIR the optimum source impedance for the NE5534 was ~2kOhm which prooves why it was used very often in Phono-stages. The AD797 is optimized for 200Ohms source impedance, so it´d be off of the best value and probabely no better than the NE5534, even though it features spectacular low voltagenoise figures. JFET input input OP amps have their optimum noise source impedance in the range of >>2kOhms and MOSFET Oamps even much higehr.
A OPA627 features very low voltagenoise figures for a JFET-input OP-amp, similar to the NE5534, but of course much better currentnoise figures. So it´ll beat the NE5534 and the AD797 noisewise. But it is costly and as all ´fast´ OPamps it requires care with the power supply. A alternative with even lower noise could be the AD743 (lower voltage noise as well as lower 1/f).
I think I read in an article by J.L.Hood that a voltagenoise figure of <5nV/sqrHz were needed for acoustic ´transparency´ noisewise. A TL072 with its 18nV and high 1/f sure doesn´t fall into that category.
jauu
Calvin
generally speaking, one couldn´t claim which is better here noisewise, JFET or bipolar. It depends on the circumstances.
Generally one can only say that JFETs show lower noisecurrent values -which dominate with high source impedances and bipolars show lower voltagenoise that dominates with lower source impedances.
The problem with MMs is that they are somewhere just on the edge.
Loaded with 47kOhms and a couple of pFs the source impedance the OPamp input ´sees´ will be around 1kOhm starting at dc and rising over ~5kOhms at 1kHz to maybe 30kohms at 20kHz. AFAIR the optimum source impedance for the NE5534 was ~2kOhm which prooves why it was used very often in Phono-stages. The AD797 is optimized for 200Ohms source impedance, so it´d be off of the best value and probabely no better than the NE5534, even though it features spectacular low voltagenoise figures. JFET input input OP amps have their optimum noise source impedance in the range of >>2kOhms and MOSFET Oamps even much higehr.
A OPA627 features very low voltagenoise figures for a JFET-input OP-amp, similar to the NE5534, but of course much better currentnoise figures. So it´ll beat the NE5534 and the AD797 noisewise. But it is costly and as all ´fast´ OPamps it requires care with the power supply. A alternative with even lower noise could be the AD743 (lower voltage noise as well as lower 1/f).
I think I read in an article by J.L.Hood that a voltagenoise figure of <5nV/sqrHz were needed for acoustic ´transparency´ noisewise. A TL072 with its 18nV and high 1/f sure doesn´t fall into that category.
jauu
Calvin
frienkly none of the above will satisfy, they will produce the sound, but far far from what is possible
I'm having a ball with my $15 Herald Electronics Disco Mixer I found at the flea market. I then put $25 in parts in it; see this thread:www.diyaudio.com/forums/analog-line-level/164102-improving-disco-mixer-mid-fi-performance.html. I'm using ST33078 op amps. I could cut the hiss even more theoretically by increasing the RIAA cap by 10X and decreasing the feedback resistor by 10x but it sounds so good those parts are gathering dust in the bins. The advantage of a mixer, you can leave the record player, CD player, and FM radio all plugged in and balanced, you don't have to fiddle with a selector switch or a master volume pot to switch from one to the other. Just turn on the input device, it plays immediately. I converted the microphone input to an FM radio input by deleting the op amp and jumpering.
Herald is Japanese, there might be some of these RA88a's in the flea market or charity resale shop in the Southern Hemisphere, since non-computer disco is now dead. Mine had great slider pots, no complaints there, most of the stupidity was in the power supply. The NJM4558 op amps weren't much either, to start with, they hiss. They were dip package so it was easy to try replacements: I did install phosphor bronze sockets in case I want to try LM4562 or something.
Peavey also made a disco mixer which might be modifiable for more fidelity, but I've never actually seen one. Peavey has great schematic diagrams. Regular mixers don't have an RIAA input. Stay away from Behringer, they have secret schematics and use SMD parts and flat cables and that means repairs/mods must be made by gnomes or elves, in my opinion. And I have tiny Native American origin hands and fingers. I'm using a Shure M97 Era IV MM cartridge at 1.5 g.
Herald is Japanese, there might be some of these RA88a's in the flea market or charity resale shop in the Southern Hemisphere, since non-computer disco is now dead. Mine had great slider pots, no complaints there, most of the stupidity was in the power supply. The NJM4558 op amps weren't much either, to start with, they hiss. They were dip package so it was easy to try replacements: I did install phosphor bronze sockets in case I want to try LM4562 or something.
Peavey also made a disco mixer which might be modifiable for more fidelity, but I've never actually seen one. Peavey has great schematic diagrams. Regular mixers don't have an RIAA input. Stay away from Behringer, they have secret schematics and use SMD parts and flat cables and that means repairs/mods must be made by gnomes or elves, in my opinion. And I have tiny Native American origin hands and fingers. I'm using a Shure M97 Era IV MM cartridge at 1.5 g.
Last edited:
I built this phono preamp Actidam MkII:
Hobby-bastleni-Aktidamp
exceptionally good sound for such simple curcuit
Than I built two other much more complicated versions, Mk III and Mk IV, while a lot more work, they obviously are better, Mk III the best.
Here is the link to Mk IV:
http://sjostromaudio.com/dudek_files/ad4.pdf
Hobby-bastleni-Aktidamp
exceptionally good sound for such simple curcuit
Than I built two other much more complicated versions, Mk III and Mk IV, while a lot more work, they obviously are better, Mk III the best.
Here is the link to Mk IV:
http://sjostromaudio.com/dudek_files/ad4.pdf
A rough but quite usable approximation is to take the cartridge impedance at 3852 Hz and optimise the noise for that impedance. With some simplifications one can prove that minimising the RIAA- and A-weighted noise is equivalent to minimising the noise at 3852 Hz, if input current and voltage noise are both white. A typical moving-magnet cartridge with an inductance of almost half a henry then has an impedance around 12 kohm. The 2 pA/sqrt(Hz) of an AD797 then has the same influence as 24 nV/sqrt(Hz) of voltage noise.
Taking into account the effect of the capacitive and resistive load, you end up at a slightly lower effective impedance, typically 10 kohm instead of 12 kohm. The 2 pA/sqrt(Hz) of an AD797 then has the same influence as 20 nV/sqrt(Hz) of voltage noise.
NE5534A, OPA627 and AD743 are indeed good choices for moving-magnet cartridges.
Here is a top quality DIY phono pre-amp project. And there's a big thread on it right here in the Pass Labs forum.
http://www.passdiy.com/pdf/PEARL 2.pdf
Graeme
http://www.passdiy.com/pdf/PEARL 2.pdf
Graeme
Hi,
Marcel, do You have a source or text that explains the theory. Why exactly 3852Hz? If I understand correct You calculate the impedance the input stage sees at 3852Hz, convert that impedance to a noise current/voltage of the input device and integrate over 20Hz-20kHz to get the effective noise voltage? Or do You do an integration with a bandwidth limit of 3852Hz?
Linsley Hood mentiones (or rather he assumed) that the effective bandwidth for noise calaculations in RIAA stages were probabely around 2kHz.
jauu
Calvin
Marcel, do You have a source or text that explains the theory. Why exactly 3852Hz? If I understand correct You calculate the impedance the input stage sees at 3852Hz, convert that impedance to a noise current/voltage of the input device and integrate over 20Hz-20kHz to get the effective noise voltage? Or do You do an integration with a bandwidth limit of 3852Hz?
Linsley Hood mentiones (or rather he assumed) that the effective bandwidth for noise calaculations in RIAA stages were probabely around 2kHz.
jauu
Calvin
Check these out:
Le Pacific JFET Phono Preamp for MM and MC Cartridges
Salas Simple Phono Stage:
http://www.diyaudio.com/forums/analogue-source/129126-simplistic-njfet-riaa.html
For latest info on Salas Phono stage, select Evolution link on first post.
Boozhound Phono Stage kit:
http://diyaudioprojects.com/Solid/JFET-Phono-Preamplifier-Kit/
Le Pacific JFET Phono Preamp for MM and MC Cartridges
Salas Simple Phono Stage:
http://www.diyaudio.com/forums/analogue-source/129126-simplistic-njfet-riaa.html
For latest info on Salas Phono stage, select Evolution link on first post.
Boozhound Phono Stage kit:
http://diyaudioprojects.com/Solid/JFET-Phono-Preamplifier-Kit/
Last edited:
Hi Calvin,
It is explained in an article written by me in the October 2003 issue of Electronics World, "Noise and moving-magnet cartridges". That 3852 Hz is the square root of a ratio of two integrals of squared magnitudes of transfer functions, as explained in the article. When you use a different type of noise weighting than the A-weigthing I used, you will get a somewhat different frequency.
By the way, it is not equal to the RIAA- and A-weighted equivalent noise bandwidth.
Best regards,
Marcel
Last edited:
G'day all, I'm a big fan of the ESP P06 having built quite a few over the years for different systems. It is my 'reference' standard. I have heard none better.
I use OPA2134 dual op amps and the P06 is a stunningly clean, dynamic yet musical sounding phono stage. I have actually used mine with the AT95E and it sounds wonderful, particularly with Classical music! Regards, Felix.
I use OPA2134 dual op amps and the P06 is a stunningly clean, dynamic yet musical sounding phono stage. I have actually used mine with the AT95E and it sounds wonderful, particularly with Classical music! Regards, Felix.
May I humbley suggest the LM4562. I've heard both. No contest. If you can switch out, try the LM4562 or other from National that's made for HiFi audio. Price is nice too. I believe it's under $5 US.
I replaced the opamps in a Vincent PHO111 phono pre with the all the '70's opamps it had installed. It was an obvious improvement.
Attached is the LM4562 specs in a jpeg. Right under the specs is the Typical Application, a RIAA phono pre.
Attachments
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.