Some time ago I posted a thread where I asked if anybody had any opamp based riaa design to recomend. I got a few answers and paulb gave me the following webadress:
http://www.national.com/an/AN/AN-346.pdf
I decided to use the design described in this application note. This design is a two stage riaa phono preamplifier.
Currently I use BB opa 37 in the first gainstge an BB opa 606 in the second gainstage. The result is shown in the following pictures.
http://www.national.com/an/AN/AN-346.pdf
I decided to use the design described in this application note. This design is a two stage riaa phono preamplifier.
Currently I use BB opa 37 in the first gainstge an BB opa 606 in the second gainstage. The result is shown in the following pictures.
Attachments
The sound is nice. Good soundstage, relaxed but dynamic..
However it has a somewhat enhanced s-sound. I wonder why ?😕
However it has a somewhat enhanced s-sound. I wonder why ?😕
Hi Cobra2
I`m not using any DC blocking caps. There is no DC at the outputs.
Could it be the load capacitance ? 🙄
I`m not using any DC blocking caps. There is no DC at the outputs.
Could it be the load capacitance ? 🙄
Chris said:
Have you been able to eliminate the vinyl itself? Is it the new amp or is it the LP?
Have you checked the input capacitance? Maybe you need a trim? Some pickups needs up to 400 pF.
peranders said:
Hi 🙂
The pickup i use (ortofon om 10) should be loaded with about 100 - 200pF. I have tried both values with no real improvment IMHO. Currently I have no load capacitance and it`s better I think.
Could it be that the cable I use introduce enough capacitance ?
Normal TT cable has approx. 100 pF per meter and must of course be included.
If you connect the TT to an another RIAA amp, do you get the same S-sounds?
I salute you also to your achievement (I can feel the joy you feel) but unfortunately your wiring doesn't get any high score. NEMKO had
their heads. Think tidyness. Separate 230 volts from the rest. NO unisolated parts!
Which circiut have you built? The last one in the application note?
If you connect the TT to an another RIAA amp, do you get the same S-sounds?
I salute you also to your achievement (I can feel the joy you feel) but unfortunately your wiring doesn't get any high score. NEMKO had
their heads. Think tidyness. Separate 230 volts from the rest. NO unisolated parts!Which circiut have you built? The last one in the application note?
Hi Peranders
Yes Nemko would most certainly their heads if they could see
the wiring. Thats why I`m in the process of making it better right now...
No more unisolated parts !!!
Yes Nemko would most certainly
their heads if they could seethe wiring. Thats why I`m in the process of making it better right now...
No more unisolated parts !!!
Does it work yet?Arne, do you have DC-servo PLUS capacitor? Either one fat mama or DC-servo. Check carefully how you choose between "Linear Tech original" and "P-A original" feedback network.Check here and the part about DC-servo.
Note also parts for optional compensation.
We had a diy party when we used my monster QSXM2 together with a homemade TT with tangential arm. Look at the painting of the TT! I thought it was plastic imitation.
We hadn't time to REALLY listen to the amp or TT but it didn't sound bad anyway. The power came from two norwegian Mascot lab PS, not very high tech.
http://www.hififorum.nu/topic.asp?TOPIC_ID=14408
Yes, it works
Even being a bit "over-stuffed" !
Have to verify the parts-count again...too many options...
BTW, may I also have a few more dB (4-5) gain on MM?
And how much gain is it set up for on MC?
Arne K
Even being a bit "over-stuffed" !
Have to verify the parts-count again...too many options...
BTW, may I also have a few more dB (4-5) gain on MM?
And how much gain is it set up for on MC?
Arne K
I suggest that you make the DC-servo working as intended, remove the C11, C12, C13. Use not R5, R23.
You may otherwise get the "golden ears" haunting you. You must achieve accurancy below 0.1 dB! 😉
More gain:
MM R6, MC R4. Half the value double gain = 6 dB
MC has 20 dB more gain. Note the differnce between R6 and R4.
You may otherwise get the "golden ears" haunting you. You must achieve accurancy below 0.1 dB! 😉
More gain:
MM R6, MC R4. Half the value double gain = 6 dB
MC has 20 dB more gain. Note the differnce between R6 and R4.
Chris said:
The Ortofon OM10 is a bit sibilant, that's almost certainly the cause of your "enhanced s-sound." I had an OM10 in an SME3009 S2, and had the same problem, so I changed the stylus for an OM30 stylus (the bodies are identical), and the problem went away.
Re: QSXM3
Will do, PerAnders, have not listened to it yet, more than confirming that it works, and is very quiet 🙂
Arne K
Will do, PerAnders, have not listened to it yet, more than confirming that it works, and is very quiet 🙂
Arne K
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