Hi everyone,
My RIAA literally went to smoke, so my 1210 is just staring in the wall doing nothing, i thought this was the best excuse to make an attempt on building the RIAA Pacific.
I have made a very quick drawing in EAGLE based on the Boozehound JFET Phono Preamp, which i would like to receive some comments on, please be aware that this is my first serious audio circuit.
Caps:
C2, C7, C3 = MKP1837
C6 = RIFA PHE427
C4 = WIMA FKP2
C10, C9 = Nichicon Muse KZ
Schematic:
Board:
My RIAA literally went to smoke, so my 1210 is just staring in the wall doing nothing, i thought this was the best excuse to make an attempt on building the RIAA Pacific.
I have made a very quick drawing in EAGLE based on the Boozehound JFET Phono Preamp, which i would like to receive some comments on, please be aware that this is my first serious audio circuit.
Caps:
C2, C7, C3 = MKP1837
C6 = RIFA PHE427
C4 = WIMA FKP2
C10, C9 = Nichicon Muse KZ
Schematic:
Board:
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Boozhound Laboratories: JFET Phono Preamp Kit
This is a bit modified version and works very well. I have assembled it on a veroboard and it sounds great.
This is a bit modified version and works very well. I have assembled it on a veroboard and it sounds great.
I was very close to buying that kit, but i wanted to do my own attempt. Only thing that bothers me are the Russian caps that are slightly expensive. Could MCap not be a replacement? I made an update to my schematic.
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I have the Boozehound kit, and built it first w/the Russian PIO caps.
I now have a sliver mica at c4, Jantzen silver at the output, REL polystyrene at C7, Vishay 1837 at c2 and a wima at c3. The sound is much more open and aggressive. To me, the Russian PIO caps are rolled off and soft but some may find that appealing.
If I was upgrading/replacing just one cap it would be the output cap and/or the interstage coupling cap.
Also, I am running 16 AA batteries which works well but I'd like to investigate regulated power supplies in the future...batteries are kind of a pain.
I now have a sliver mica at c4, Jantzen silver at the output, REL polystyrene at C7, Vishay 1837 at c2 and a wima at c3. The sound is much more open and aggressive. To me, the Russian PIO caps are rolled off and soft but some may find that appealing.
If I was upgrading/replacing just one cap it would be the output cap and/or the interstage coupling cap.
Also, I am running 16 AA batteries which works well but I'd like to investigate regulated power supplies in the future...batteries are kind of a pain.
Have you tried any other than the Jantzen silver on the output? I see they go for 15€ from Germany and a bit higher in Denmark, even though they are made here..
Id love to hear more about that, are you thinking in terms of noise filtering a AC-DC converter output?
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Is there anything i can do to make it more "visible"?
I definitely agree with you, unfortunately i don't have the resources/luxury of testing infinite amount of capacitors.
) Although i find the performance great with the chosen.
Enjoy your creation. You need not continue to change capacitors if you like the sound of the preamp. It's always a very personal decision. Others may not approve of your capacitor selections. If the preamp sounds good to you ...... enjoy it. You are the best judge of the sound that is satisfying to your ears!
I agree with you, its without a doubt a personal reference when it comes to the ears. Although i want to avoid using batteries, is there any optimal way of using 24VDC from a converter and eventually filtering the noise, perhaps a simple LC filter circuit?
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Batteries are a pain. I'm using nothing more than a junkbox 28 volt switching supply.
Between the supply and the preamp, I've added some resistors and capacitors.
As I recall, I put a 270 ohm resistor in series with the dc+ output and another in series with the dc- output of the power supply. On the dc input of the preamp, I used a 3300uf capacitor followed by a 470 ohm resistor and another 3300uf capacitor. I added a .47uf capacitor across the dc power source at the point where it connected to the actual preamp circuitry. It's quiet.
Between the supply and the preamp, I've added some resistors and capacitors.
As I recall, I put a 270 ohm resistor in series with the dc+ output and another in series with the dc- output of the power supply. On the dc input of the preamp, I used a 3300uf capacitor followed by a 470 ohm resistor and another 3300uf capacitor. I added a .47uf capacitor across the dc power source at the point where it connected to the actual preamp circuitry. It's quiet.
Have you tried any other than the Jantzen silver on the output? I see they go for 15€ from Germany and a bit higher in Denmark, even though they are made here..
Well, I had the Jantzens left over from another project...
Here's some good web sources of cap tests...
Humble Homemade Hifi
Eric's Hi-Fi Blog: Capacitor shoot out
If it was me, I'd use as many Vishay 1837s as I could find in the right values and wima for the rest. That's a good budget set up. I'd skip the PIO russian caps unless you buy the BHL kit. I'd use a silver mica for the .001. It's basically just a bypass cap.
If you want to spend more I would look into REL polystyrene caps. They are my current favorite. Clarity cap has a nice range of affordable caps as well.
Really, at this point you are just tuning the sound of the system. Consider the wimps or 1837 as the baseline. Want darker? Go w/the russian PIOs. Want more detail or a more lively sound? Try something like a Jantzen silver.
Also, you can experiment with loading (the 47K resistor at the input). A higher value will be brighter, lower darker. Depends on your cartridge.
Also, I'd increase the 220uf power supply caps to 470 or 1000uf. The cost will be very little more.
There are two types of power supplies (other than batteries), Switching and linear. Switching supplies are the small "box-type" plastic things that plug in the wall. Adding caps and or filters may make these quieter. But its not really the best solution.
A linear PS consists of a transformer, rectifier and in this case, a regulator. It is more complex to build and requires more parts.
For this preamp, a great solution would be a linear supply with a lm317 regulator or maybe even something more exotic like a shunt reg. It could be better than batteries. I am using batteries which sound good but I'd like to be able to leave my system on all the time so I am investigating linear supplies.
I have a few LM317 laying around, this may be a fine solution i might aswell integrate
)I just increased the 220u cap.
And i added the forgotten load resistor REL Polystyrene sounds interesting, i have read about them but did not consider it for this application, perhaps i should buy a bunch anyway and test them on my breadboard before deciding on which one to go for (second thoughts).- Status
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