That's clear for me now. It's worth a try, this is simple to make. If it doesn't work, the parts can allways be taken for other projects. If this works well, at least with batteries, it only demands a good pair of resistances for signal and 0,1μf caps and there are two Bee Wax Jupiters available.
At this point, making and testing a UBib takes one hour. That's some training...
At this point, making and testing a UBib takes one hour. That's some training...
It will work and it will sound pleasant. Its just that the 100R gate resistor and the 50R source resistor are more suitable for source impedance of MM class. Those have ten times more signal than MC though. Such resistor values don't add to the MM source noise because smaller than the source impedance. It will simply not have the resolution of thoroughbred MC pre-pre circuits, that's all.
Hum...interesting!😀
Can we change that? I mean, I can take another circuit, but can we change those values in such a way that it will be a true MC class?
As it is, it is good for MC cartridges with high output, like the entry level Dynavector...
No we can't. The source pin resistors especially are integral to its biasing and gain setting. About the gate stopper resistors maybe you can lower their value or not, if nothing will sound weird by doing so in practice. They form an RF filter with the JFET's parasitic input capacitance essentially. For stability. The need for those filters can be integral or installation dependent. The designer knows.
Looking to your circuit (2SK170 BL MC step up amp),
There is a 7809 regulator, near the multiplier capacitor.
Why not to forget the 4700μf as raw dc and replace the 7809 reg by a UBib wiyh a very good big cap?
I finished the Jfet Phono from Booz,
JFET Phono/RIAA Preamplifier kit – Boozhound Laboratories
fed by a beautiful UBib, with a Mundorf cap. The RIAA has very nice parts and looks very very good.Can't wait to hear it.
I am tempted to one, based in your circuit, if there is no board for sale.
I would like to have a good MM, a "middle" MM/MC like yours, and a true MC.
Salas, do you have available RIAA boards?
There is a 7809 regulator, near the multiplier capacitor.
Why not to forget the 4700μf as raw dc and replace the 7809 reg by a UBib wiyh a very good big cap?
I finished the Jfet Phono from Booz,
JFET Phono/RIAA Preamplifier kit – Boozhound Laboratories
fed by a beautiful UBib, with a Mundorf cap. The RIAA has very nice parts and looks very very good.Can't wait to hear it.
I am tempted to one, based in your circuit, if there is no board for sale.
I would like to have a good MM, a "middle" MM/MC like yours, and a true MC.
Salas, do you have available RIAA boards?
You can replace the 7809 with any reg of your liking set at 9V output.
FSP boards are discontinued until I will revise that phono with modified custom Ubibs and some sensitivity settings DIP switches or jumpers. Not easy work, it will take time to reform and verify. That's not a pre pre, its a full phono preamp that you select few parts values for building it to a sensitivity. All things described in its pdf guide. No pre-pre only boards I ever issued. When deciding to go FSP its not a cheap or too easy build, mind you. Ask Tea if he was any classic FSP RIAA board left, or I may have one or two left from my personal samples. You would need him for selected genuine 2SK369s at least, if you will go that route anyway. Use PM.
I will have to move this last few posts discussion in the NJFET simplistic RIAA phono thread at a later point because its OT here.
FSP boards are discontinued until I will revise that phono with modified custom Ubibs and some sensitivity settings DIP switches or jumpers. Not easy work, it will take time to reform and verify. That's not a pre pre, its a full phono preamp that you select few parts values for building it to a sensitivity. All things described in its pdf guide. No pre-pre only boards I ever issued. When deciding to go FSP its not a cheap or too easy build, mind you. Ask Tea if he was any classic FSP RIAA board left, or I may have one or two left from my personal samples. You would need him for selected genuine 2SK369s at least, if you will go that route anyway. Use PM.
I will have to move this last few posts discussion in the NJFET simplistic RIAA phono thread at a later point because its OT here.
I have finally found some time and completed the FSP.
Only best impressions so far.
I'm currently tuning for cartridge loading and C2Y value, before I put them into chassis.
Many thanks to Salas for sharing and supporting such great designs with us and to Tea Bag for all his effort on this project.
Only best impressions so far.
I'm currently tuning for cartridge loading and C2Y value, before I put them into chassis.
Many thanks to Salas for sharing and supporting such great designs with us and to Tea Bag for all his effort on this project.
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Congratulations. Why there is a big capacitor hanging to the side, bypass? For which cartridge and turntable are you tuning for?
Hi Salas,
I have used 2X1uF output caps for each channel I had in stock, in parallel.
The cartridge is an at440mlb and the turntable is sl1210mk2.
I have settled to 47K loading with no extra C loading and C2Y:100pF
I have used 2X1uF output caps for each channel I had in stock, in parallel.
The cartridge is an at440mlb and the turntable is sl1210mk2.
I have settled to 47K loading with no extra C loading and C2Y:100pF
Yes there is enough capacitance in the TT wires and in the JFET input. Audio Technica MMs usually don't like any extra. You kept the transfer curve slightly rising also which is appropriate for most MM carts. Thus your tuning settings come across very logical.
You could maybe get by well enough with single 1uF output capacitor if your line pre-amp has high impedance input. Do try with only one at a point so if its still sounding good in your system, not overdamped, to can save your second expensive Clarity output coupling capacitor for another project. And for the assembly to become more manageable without any side hanging heavy parts.
Yes, exactly. Tonearm +interconnect parasitic capacitance measured around 80pF, plus JFET input capacitance probably around 80pF, well into recommended 100-200pF load capacitance for an at440mlb.
My pre-amp has 50K input impedance. Have just removed the second 1uF output capacitors for evaluation.
My pre-amp has 50K input impedance. Have just removed the second 1uF output capacitors for evaluation.
hello Salas and every one, the 2SK369BL and 2sk170 is very hard to find it,specially for the 2sk170GR,is there any on production part to replace them?
any comments and suggestion will be great appreciate.
Best Regards
Xiaojun
any comments and suggestion will be great appreciate.
Best Regards
Xiaojun
Thanks to Salas for a great project and to Tea Bag for the bits and pieces. Apologies for for not posting earlier, the phono pre has been singing for about 6 months. It's an industrial build as far as the caps go. NOS Panasonic PP caps from my parts bin, surplus polystyrene for C2Y. I did splurge for Vishay TX2575 for the loading resistors. 110ohm for the MC to load my Denon DL103, 47K for the MM for a yet to be listened to Garrott Bros. P77i.
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Nice builds. How do you like it with the DL103? I had usually found my DL103R better at about 200R loading but the regular DL103 maybe differs in loading preference.
I had been using the original Pearl with a pre-pre and found that I preferred the DL103 loaded at 100ohms so just went with that. Your pre was a bit bright at first but I thought I should let it run in a bit. After about 10 hours it smoothed out and I'm really enjoying it. That's why I haven't mounted the Garrott yet. The DL103 is on a Linn LP12 with the Ittok LVII. I have a Rega P3 that I'll probably setup with the Garrott.