I wanted to post a couple of pics of my latest build. I also wanted to extend a big thank you to salas who is unbelievably generous with his time and knowledge. I will box this up in two chassis this weekend. Even sitting in the open and picking up some hum this sounds great. I thought I might need a bigger output cap, but listening I'm not sure I do. Every question I had was already asked and answered in the thread. OK enough wasted time...back to listening and making dinner for the family...
Thanks again, Evan
Thanks again, Evan
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A small hint. Try put a finger on the metal enclosed FT caps. If hum plays up when doing that, ground their cans to the PSU ground return point on the phono board. Maybe only the 47n ones and 0.1u inter-stages can suffer fields due to they couple a low signal still. CAT-5 single strands touching each Alu can are enough to connect them to ground efficiently and make them shields to their foils.
Thanks for the advice...will do. My chassis will be here tomorrow. I have gotten away with wooden enclosures on my other pieces of equipment, but the phono preamp is much more sensitive. This circuit was my first DIY build, and I am learning that experience building goes a long way towards sound quality, even if I am a far from the level of knowledge floating around here.
Even in the metal chassis (which must be grounded to PSU level GND also), you will find that referencing the metal cans or even closing the lid will reduce hum. There is nothing more sensitive to make for such nuisances than MC phono or studio mic preamp in audio. What is your gain and cart again? I see it can play recordable CDs also in your pic, you evolved it too far in tech.
Gain is only 43db. I have an old adcom cross coil cart. I believe it is 2.3mv output. My old build had a slight hum only noticeable with the needle off the record and the volume turned all the way up. I am hoping to do better this time. As it stands this unit already betters the old one. The homemade cd is a relic from some bit torrenting we did for a while...until we got called out by disney for downloading/uploading a movie for the kids, but that is another story.
Hi ,
How about low noise and high yfs JFET 2SK3557 from Sanyo as close replacement for 2SK170.
http://www.onsemi.com/pub/Collateral/2SK3557-D.PDF
How about low noise and high yfs JFET 2SK3557 from Sanyo as close replacement for 2SK170.
http://www.onsemi.com/pub/Collateral/2SK3557-D.PDF
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Thanxz Salas,
Soldering smd is fun.
These are ready available and low cost alternatives.
Russian PIO for output
Anyone have experimented this kind of capacitors for output decoupling ?
http://i.ebayimg.com/t/OMBG-2-Paper-PIO-capacitor-1uF-200V-10-Lot-12-/23/!BphCRrQBGk~$(KGrHqQOKjYEuhMkfm-IBLryeZH6cQ~~_3.JPG
Anyone have experimented this kind of capacitors for output decoupling ?
http://i.ebayimg.com/t/OMBG-2-Paper-PIO-capacitor-1uF-200V-10-Lot-12-/23/!BphCRrQBGk~$(KGrHqQOKjYEuhMkfm-IBLryeZH6cQ~~_3.JPG
circular holes are good.
The frequencies that leak through have wavelengths comparable or shorter than the hole diameter.
Slots are the big problem in leaking lower frequencies.
A lid that is not tightly closed can leave a long slot for medium frequencies to leak in.
