"EL CHEAPO" mm/mc riaa preamp
The Analog Addicts Phono Preamp
By Thorsten Loesch
It is also called "El Cheapo" (low price)
Hope noone will hang me, if I provide a schematic.
I have changed the size a bit, to fit DiyAudio.com.
Best is to read the whole article, that Thorsten Loesch have written.
See Link in post above!
/halo
The Analog Addicts Phono Preamp
By Thorsten Loesch
It is also called "El Cheapo" (low price)
Hope noone will hang me, if I provide a schematic.
I have changed the size a bit, to fit DiyAudio.com.
Best is to read the whole article, that Thorsten Loesch have written.
See Link in post above!
/halo
Attachments
Mad_K said:
i'll be keen to hear what you think of it when its done!
Ive been meaning to build all of these simple phono circuits and do a comparison of each to mark the differences for future reference..
Hi,
Speak of the Evil one....
Not much to say about this thing really. I started fafelling about with Selfs "Precision Preamp" Phonocircuit. It sounded BAD. So I messed about a lot and tried many things.
Doing this circuit with lead acid battery power, OPA637A and a 10k Pot (later an unusual active linestage with a FET Buffered LM6181 and Volume control with a 1k Shunt Pot and a 150 Ohm output resistor) sounded rather decent for solid state. Acrylic case BTW, mixture of hardwiring and PCB.
Still, I like valves and transformers better. Butafter you put don the long green for a pair of S&B TX-103 MC Steups and the same amount for the LCR RIAA EQ Module and shelled out the green for a PSU using 8pcs 10H chokes and 6pcs 120uF Film Capacitors you appreciate just how good this little job is for the money, how simple to build.
And the price of a pair of OPA637 plus a pair of 2SK147 and four 12V/2.1AH Lead acid batteries is not THAT outrageous. Hell, my current RIAA Stage clocks in at near £ 1,000 in materials uses near unobtanium NOS Valves and it is NOT ten times better than the little ugly duckling solid state stepchild. In wood, netal and all it looks a lot better though.
Sayonara
Speak of the Evil one....
Not much to say about this thing really. I started fafelling about with Selfs "Precision Preamp" Phonocircuit. It sounded BAD. So I messed about a lot and tried many things.
Doing this circuit with lead acid battery power, OPA637A and a 10k Pot (later an unusual active linestage with a FET Buffered LM6181 and Volume control with a 1k Shunt Pot and a 150 Ohm output resistor) sounded rather decent for solid state. Acrylic case BTW, mixture of hardwiring and PCB.
Still, I like valves and transformers better. Butafter you put don the long green for a pair of S&B TX-103 MC Steups and the same amount for the LCR RIAA EQ Module and shelled out the green for a PSU using 8pcs 10H chokes and 6pcs 120uF Film Capacitors you appreciate just how good this little job is for the money, how simple to build.
And the price of a pair of OPA637 plus a pair of 2SK147 and four 12V/2.1AH Lead acid batteries is not THAT outrageous. Hell, my current RIAA Stage clocks in at near £ 1,000 in materials uses near unobtanium NOS Valves and it is NOT ten times better than the little ugly duckling solid state stepchild. In wood, netal and all it looks a lot better though.
Sayonara
And here's how it turned out...
As I've changed the circuit somewhat I'm not allowed to say it's Thorsten's, but I think it is close enough.
Changes:
1. Only MM stage.
2. Not rechargeable batteries.
3. None of the specified components (brands) are used, except for the OPA637BP.
3. Supply filtering changed: Elna RJH 1000uF + 100nF Rifa MMK.
4. RIAA caps are WIMA FKP2, 2,5% but matched to exact value.
5. Outputcaps are Elna RJH 330uf (arranged as descibed) bypassed with 0,47uF SCR.
So, here comes the pics; board:
As I've changed the circuit somewhat I'm not allowed to say it's Thorsten's, but I think it is close enough.
Changes:
1. Only MM stage.
2. Not rechargeable batteries.
3. None of the specified components (brands) are used, except for the OPA637BP.
3. Supply filtering changed: Elna RJH 1000uF + 100nF Rifa MMK.
4. RIAA caps are WIMA FKP2, 2,5% but matched to exact value.
5. Outputcaps are Elna RJH 330uf (arranged as descibed) bypassed with 0,47uF SCR.
So, here comes the pics; board:
Attachments
Maybe, you are wondering about the sound?
The answer is I don't really know yet, but it seems very promising; neutral, especially in the critical midband. A little relaxed, dark-sounding maybe. Very precise and accurate. Bass is solid, and treble is excellent. I've tried (and listened to) some of the other simple RIAA pre's, but always found something that I didn't like about them. Noise is as low as one can expect. I have to turn the volume all the way up and put my ear near the speaker to hear anything. Surface noise is also very low. Previously, I have always had a problem with static jumping through when changing records. Somehow it's gone now...?
This is the one for me, thank you very much
BTW, it worked very well with the OPA604 also
The answer is I don't really know yet, but it seems very promising; neutral, especially in the critical midband. A little relaxed, dark-sounding maybe. Very precise and accurate. Bass is solid, and treble is excellent. I've tried (and listened to) some of the other simple RIAA pre's, but always found something that I didn't like about them. Noise is as low as one can expect. I have to turn the volume all the way up and put my ear near the speaker to hear anything. Surface noise is also very low. Previously, I have always had a problem with static jumping through when changing records. Somehow it's gone now...?
This is the one for me, thank you very much
BTW, it worked very well with the OPA604 also
Balanced Input moving Coil-Cartridge Preamplifier
Hi ,
For a very good sounding prepre see:
http://db.audioasylum.com/cgi/m.pl?forum=tweaks&n=50205&highlight=elso+cartridge&r=&session=)
Hi ,
For a very good sounding prepre see:
http://db.audioasylum.com/cgi/m.pl?forum=tweaks&n=50205&highlight=elso+cartridge&r=&session=)
Re: And here's how it turned out...
Hi,
Nice job. And good to hear you like the results. Some comments on sound later....
As you say, it's close enough. You can call it "Thorstens" if you like, though I think it is actually Mad_k's RIAA Pre and a nice one too.
Using Alcali batteries is still a battery supply, it qualifies too...
Hi,
Nice job. And good to hear you like the results. Some comments on sound later....
As you say, it's close enough. You can call it "Thorstens" if you like, though I think it is actually Mad_k's RIAA Pre and a nice one too.
Using Alcali batteries is still a battery supply, it qualifies too...
Thanks for your comments Kuei Yang Wang!
As I am (was?) in the progress of testing different MM phono-pre's I did them all with the same type of components (more or less). I think you are right about the WIMA's, but I kind of like it..
Later, I will build this circuit one more time with different (better) components, and take your advices with me, and maybe implement the MC-part also.
Now it's time to do some serious listening
As I am (was?) in the progress of testing different MM phono-pre's I did them all with the same type of components (more or less). I think you are right about the WIMA's, but I kind of like it..
Later, I will build this circuit one more time with different (better) components, and take your advices with me, and maybe implement the MC-part also.
Now it's time to do some serious listening
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