In the German computer magazine "c't" a simple high-class RIAA amplifier was published and is maybe of interest here.
It was mainly constructed for recording/transferring LPs to the digital world. But the design is quite capable and can be used as a good general MM-RIAA amp (very good indeed, and much better than the usual "primitive" one-opamp circuit. It is nevertheless maybe not in the class of the Pearl and other highend designs, but only very few people have the subsequent highend turntables anyway ...)
German speaking members can download more information (article, soundfiles, software) from http://www.heise.de/ct/ .
There is a good quality PCB available for 8 EURO only.
I did two amps with some modifications:
1. Input
I ommitted the 3k9 series input resistor (R1) and changed the 43k input resistor (R2) to the nominal value 47k. To get an input RF filter it seems better to me to use a 3winding ferrite bead instaed of R1. I used a 0R link.
2. Output:
I paralled the output capacitor C7 (in the first version a 10yF Philips K030, in the second version a 100yF Roderstein) with a 1yF Philips MKT-HQ capacitor. Then there is a 100k resistor to ground and a 100R series resistor, driving the cable.
3. Opamps:
Although this RIAA amp works very good with the LM833 (and the NE5532A), I personally think that the OPA2134 sounds far better, too good almost... It reveals the finest distorsions from the cartridge etc. (And nobody should tell me anymore that there is no sound difference between opamps...)
4. Gain:
I ommitted P1, because adjustments have to be permanent, I think.
I used a 27k resistor (40db gain at 100Hz ) first but found that more gain (less feedback) sounds much better. So I replaced P1 with a 47k resistor and a link.
5. Input lowpass:
I used a y33 MKP and a y47 MKT-HQ with equal success.
All resistors and capacitors are selected and measured of course; resistors are metal film from Roederstein and capacitors mostly are MKT-HQ from Philips.
The circuit is orginally constructed for the use with 2 x 9V batteries, I used (beta phase) a standard single LM317/337 psu.
The whole amp is very quiet, almost no noise and completely hum free.
good luck
Klaus
It was mainly constructed for recording/transferring LPs to the digital world. But the design is quite capable and can be used as a good general MM-RIAA amp (very good indeed, and much better than the usual "primitive" one-opamp circuit. It is nevertheless maybe not in the class of the Pearl and other highend designs, but only very few people have the subsequent highend turntables anyway ...)
German speaking members can download more information (article, soundfiles, software) from http://www.heise.de/ct/ .
There is a good quality PCB available for 8 EURO only.
I did two amps with some modifications:
1. Input
I ommitted the 3k9 series input resistor (R1) and changed the 43k input resistor (R2) to the nominal value 47k. To get an input RF filter it seems better to me to use a 3winding ferrite bead instaed of R1. I used a 0R link.
2. Output:
I paralled the output capacitor C7 (in the first version a 10yF Philips K030, in the second version a 100yF Roderstein) with a 1yF Philips MKT-HQ capacitor. Then there is a 100k resistor to ground and a 100R series resistor, driving the cable.
3. Opamps:
Although this RIAA amp works very good with the LM833 (and the NE5532A), I personally think that the OPA2134 sounds far better, too good almost... It reveals the finest distorsions from the cartridge etc. (And nobody should tell me anymore that there is no sound difference between opamps...)
4. Gain:
I ommitted P1, because adjustments have to be permanent, I think.
I used a 27k resistor (40db gain at 100Hz ) first but found that more gain (less feedback) sounds much better. So I replaced P1 with a 47k resistor and a link.
5. Input lowpass:
I used a y33 MKP and a y47 MKT-HQ with equal success.
All resistors and capacitors are selected and measured of course; resistors are metal film from Roederstein and capacitors mostly are MKT-HQ from Philips.
The circuit is orginally constructed for the use with 2 x 9V batteries, I used (beta phase) a standard single LM317/337 psu.
The whole amp is very quiet, almost no noise and completely hum free.
good luck
Klaus
Attachments
If you want to check the RIAA network accurancy I have a Excel spreadsheet.
It's a good designing pratice to not let any capacitor hanging loose the output capacitor in you case. They can pick up charge and/or won't get discharged when the amp is disconnected.
Do you have a photo over the wonder?
It's a good designing pratice to not let any capacitor hanging loose the output capacitor in you case. They can pick up charge and/or won't get discharged when the amp is disconnected.
Do you have a photo over the wonder?
peranders,
in my modfications list you will see that I changed the schematic at the output.
The output capacitor in this circuit can also be ommitted if the following amp has an input cap anyway.
I must state that I did not develop this schematic not did I calculate the component values. I trusted this c't develloper...
But this schematic - in my opinion - did get some design elements right for a simple riaa-amp:
1. active operation for the "bass" side and passive for the treble side of the riaa curve.
2. do not attempt to use just one opamp
3. do not apply the "upper part" equalisation at the output (like Rod Elliots RIAA amp)
The result is a remarkable noise and distortion free riaa-amp for little money.
I do not have a digital camera nor a scanner, so no photos here (- I am an audio man, btw.). I tested this amp in an open test setup only, but I will do a proper case in the next days ( a classic euro sized alu box I suppose).
But believe me, it is no "wonder", just a little amp with decent sound. I use it with my Systemdek I-920 / Rega250 / AT95 at the moment to test it with a basic setup. I will change the cartridge to something slightly better tomorrow (a LinnK9 from my box or a Goldring 1024). I cannot test it with my LinnLP12 because I do not have a MC step-up amp at the moment.
Klaus
in my modfications list you will see that I changed the schematic at the output.
The output capacitor in this circuit can also be ommitted if the following amp has an input cap anyway.
I must state that I did not develop this schematic not did I calculate the component values. I trusted this c't develloper...
But this schematic - in my opinion - did get some design elements right for a simple riaa-amp:
1. active operation for the "bass" side and passive for the treble side of the riaa curve.
2. do not attempt to use just one opamp
3. do not apply the "upper part" equalisation at the output (like Rod Elliots RIAA amp)
The result is a remarkable noise and distortion free riaa-amp for little money.
I do not have a digital camera nor a scanner, so no photos here (- I am an audio man, btw.). I tested this amp in an open test setup only, but I will do a proper case in the next days ( a classic euro sized alu box I suppose).
But believe me, it is no "wonder", just a little amp with decent sound. I use it with my Systemdek I-920 / Rega250 / AT95 at the moment to test it with a basic setup. I will change the cartridge to something slightly better tomorrow (a LinnK9 from my box or a Goldring 1024). I cannot test it with my LinnLP12 because I do not have a MC step-up amp at the moment.
Klaus
The whole c't article can be found here (with diagrams and photos etc.):
http://www.heise.de/ct/02/13/224/default.shtml
http://www.heise.de/ct/02/13/224/default.shtml
lohk said:
There are approx. a dozen different ways to make a RIAA amp. Each one has it's pros and cons. As alsways certain topologies are very sensitive when it comes to choosing the right parts. It's quite possible to make a MC RIAA amp with only one opamp but the amp have to have high open-loop gain and also be rather fast.
A good example of a single-opamp MC preamp is the LFD MM0/Mistral Phonostage (essentially the same thing).
It has 56dB of gain, uses one NE5534 per channel, alongside junk like 7815/7915s and even output coupling through an elcap, which incidentally is also needed for a small correction to the bass response, and guess what ... sounds quite wonderful.
It is also remarkable for its tantalum input load resistor which costs probably as much as all of the other components put together
It has 56dB of gain, uses one NE5534 per channel, alongside junk like 7815/7915s and even output coupling through an elcap, which incidentally is also needed for a small correction to the bass response, and guess what ... sounds quite wonderful.
It is also remarkable for its tantalum input load resistor which costs probably as much as all of the other components put together
Yes, Nicke, you are right, the develloper of this riaa-amp partly followed the Application note (admittely, if you can read the article, even with a link).
Werner,
yes ok. I am open to believe anything, but I like to convince myself by trial. Will you be so kind to post the schematic or a suitable link ? I never had the chance to hear a LFD MM0/Mistral Phonostage yet.
In what stage of development is your jfet preamp btw ?
Peranders, your RIAA preamp maybe much better, but it is far more complicated and surely more expensive to make. That is completely another league. But: The Highend preamps like yours have to take up the challenge by the simple ones, and they hopefully will be very much better. (otherwise...)
And isn't your preamp QSXM3 also non-inverting ?
I do not want to be envolved in a war about the 1001 possibilities of mm-riaa-preamps. I just wanted to post this amp - because I just happend to have made two.
I found the proposed design details suitable for me: I would have done it the same way anyway. I am convinced (by the article itself and the posted National Apllication Note) that getting high accuracy and low distortion is impossible with just one opamp. I have never heard an example, but I maybe wrong, I am open to anything. There are so many more possibilities...
Klaus
ps: The PCB is availlable at http:/www.emedia.de
Ordercode#0213224B for 8,- EURO
Werner,
yes ok. I am open to believe anything, but I like to convince myself by trial. Will you be so kind to post the schematic or a suitable link ? I never had the chance to hear a LFD MM0/Mistral Phonostage yet.
In what stage of development is your jfet preamp btw ?
Peranders, your RIAA preamp maybe much better, but it is far more complicated and surely more expensive to make. That is completely another league. But: The Highend preamps like yours have to take up the challenge by the simple ones, and they hopefully will be very much better. (otherwise...)
And isn't your preamp QSXM3 also non-inverting ?
I do not want to be envolved in a war about the 1001 possibilities of mm-riaa-preamps. I just wanted to post this amp - because I just happend to have made two.
I found the proposed design details suitable for me: I would have done it the same way anyway. I am convinced (by the article itself and the posted National Apllication Note) that getting high accuracy and low distortion is impossible with just one opamp. I have never heard an example, but I maybe wrong, I am open to anything. There are so many more possibilities...
Klaus
ps: The PCB is availlable at http:/www.emedia.de
Ordercode#0213224B for 8,- EURO
NE5534/NE5532
I think that for along time this opamp family was the only one available which could fulfill all the necessities for the use with audio:
1. Low noise
2. Good sound in many different applications
3. Low price
Isn't that enough ?
When I changed from a NAD amp (forget the type, with a single 5532 for two riaa channels) in the early eighties to a NAIM preamp I learned for the first time the the really mediocre sound of the turntable was partly because of the terrible preamp (the 3020 was better, sure).
Do you know how many 5534's in the mixing consoles and elsewhere your music has already passed before it got recorded to the master tape ? Better not ask...
Klaus
I think that for along time this opamp family was the only one available which could fulfill all the necessities for the use with audio:
1. Low noise
2. Good sound in many different applications
3. Low price
Isn't that enough ?
When I changed from a NAD amp (forget the type, with a single 5532 for two riaa channels) in the early eighties to a NAIM preamp I learned for the first time the the really mediocre sound of the turntable was partly because of the terrible preamp (the 3020 was better, sure).
Do you know how many 5534's in the mixing consoles and elsewhere your music has already passed before it got recorded to the master tape ? Better not ask...
Klaus
lohk said:
You could try the one I built.
One opamp and it sounds really good....
Nicke´s phono amp
Nicke
The original....
Here you can find the schematics of the original circuit on which I based my phono amp.
Thorsten Loesh´s phono amp
Here you can find the schematics of the original circuit on which I based my phono amp.
Thorsten Loesh´s phono amp
Come one, Nicke, do you know the price of one OPA637 ? And just one opamp ? What about the buffer ?
No I was talking about good and real simple (and cheap!). An opa637 (the high praise difet mega monk) is clearly beyond that. I must admit that I never heard one in a riaa amp yet, only in I/V DACout stages.
Klaus
No I was talking about good and real simple (and cheap!). An opa637 (the high praise difet mega monk) is clearly beyond that. I must admit that I never heard one in a riaa amp yet, only in I/V DACout stages.
Klaus
lohk said:
I traced the PCB of a Mistral to come to the schematic, but as it is not public domain I do not feel free to post it. It is bog-standard, though, except for the RIAA which is not the often-seen ((R//C)+(R//C)) circuit. A last hint I can give is that the opamp's supply terminals do not look directly into the voltage regulators' outputs.
I reviewed it for TNT Audio (here).
As an aside, talking a couple of years ago to a commercial designer with a proven track record for phonostages, who at the time was working on a (fairly) low-cost phonostage, he admitted that after having gone through the usual suspects, a simple 5534 still sounded best in the front-end position.
My own JFET phono then. Originally this was something to be much Pacific-like. Later I mentally tacked on a second, alternative, output stage for more gain, an OPA637. So the basic architecture is JFET (front), RIAA, then to JFET (back) or OPA637 (back).
Power supply and additional tricks around the 637 still TBD.
All got delayed as I first had to finish my linestage. That's done now.
Have a look at "Visions In Audio" - Werner's Homepage
He has some information about Phono stages here:
Also with some Schematics
http://www.angelfire.com/music4/audio_visions/design.html
Might not be the very latest of his DIY-works.
I attach one of the JFET preamps, Werner have tried.
One of the more simpler ones.
/halo
Have a look at "Visions In Audio" - Werner's Homepageperanders said:
He has some information about Phono stages here:
Also with some Schematics
http://www.angelfire.com/music4/audio_visions/design.html
Might not be the very latest of his DIY-works.
I attach one of the JFET preamps, Werner have tried.
One of the more simpler ones.
/halo
Attachments
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.