hi all, been enjoying this preamp very much for about a year now. The only problem i have been having is it blows fuses pretty regularly. I went through 5 in the last year so i was hoping I could get something that still protects me but doesn't blow all the time. I am currently using 2.5A 250VAC fuses and my transformer is a Y23 250VA, Secondary 35 + 35V, Secondary 3.57A. Do you have any recommendations for me? Should I just go to a 3A fuse?
Its the 250VA toroidal transformer building up magnetic momentum. Are you using normal or time delay (slow blow) primary side fuse?
Thanks for the quick reply. This is the fuse I am currently using from digikey. I do believe they are slow blow. I am in the US on 120 mains.
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Yes its slow blow (Time-lag, type T). Says so also if you click on its product series documentation. I think you need 3A slow blow for not breaking without having an upstream fault but also being closely fused.
Great thanks for the confirmation. I will go with the same type of fuse but at 3A. I really appreciate the advice.
Salas!
I'm having serious build withdrawal from this project. It's an incredible preamp. I've listened to it against a few other pres I had kicking around—now for sale. LOL. Also played with the treble trim and C3.
It's fantastic. Really.
Pics of the SUT implementation since the last posts. It's pretty quiet actually—in MC mode—Just listening to the output with headphones. I need to finish up the wiring after experimenting with the quietest grounding arrangement. The center taps (orange/yellow) should really be short—but doing that will kinda lock me in to a 1:10 ratio—which will likely rule out most all Denon MC options—from my reading/research they like 1:20—I could get fancy and try to switch that...but it's getting tight in there.... I don't currently own any MC carts.... so there's that.
I'm having serious build withdrawal from this project. It's an incredible preamp. I've listened to it against a few other pres I had kicking around—now for sale. LOL. Also played with the treble trim and C3.
It's fantastic. Really.
Pics of the SUT implementation since the last posts. It's pretty quiet actually—in MC mode—Just listening to the output with headphones. I need to finish up the wiring after experimenting with the quietest grounding arrangement. The center taps (orange/yellow) should really be short—but doing that will kinda lock me in to a 1:10 ratio—which will likely rule out most all Denon MC options—from my reading/research they like 1:20—I could get fancy and try to switch that...but it's getting tight in there.... I don't currently own any MC carts.... so there's that.
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Looks very nice including the SUTs now and I am happy that you are enjoying it. Congrats 
Your tables and carts we saw in post #17646. What is the rest of your amplification system?

Your tables and carts we saw in post #17646. What is the rest of your amplification system?
Great thanks for the confirmation. I will go with the same type of fuse but at 3A. I really appreciate the advice.
Its an approximation, various 250VA toroid models differ in exact spec, but I think there is a good chance it should be OK. Get a 3.15A Time-Lag fuse also if available just in case 3A proves borderline.
Looks very nice including the SUTs now and I am happy that you are enjoying it. Congrats
Your tables and carts we saw in post #17646. What is the rest of your amplification system?
HI Salas,
Sources/
1. Turntables as you mentioned—shown earlier, the final "answer" being the SP-10MKII—already upgraded internally—I need to make a plinth (See pic). (Carts: Grado wood bodies: Statement and Reference [Soundsmith retip], AT VM540ML. I also have a Infinity Black Widow with a seriously lightweight ADC cart)
2. Hi-res digital (Tidal) into DAC (Schitt Bifrost, and Denafrips Ares II)
--> Wayne's BA18 Pre (with Mezmerize style input board BTW!) --> Aleph J or F5 --> Omega Super 3 HO monitors (CT, USA small speaker builder)
Also working on ZenMod's Iron Pre SE, and M2X, and Probably BA-3, and certainly SissySIT and definitely Cordell/3886 chip amp! LOL. I'll end up building them all looking for even more nirvana and fun. Considering some other speakers for a second system in the same room...(Tekton Compact Enzo)
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I finished my MM version of the FS NJFET preamp. After I got over the initial thrill of having it play music from both channels at the same time, I spent the next four hours listening. Every couple of songs, I would stop working just to listen, I was surprised at how it kept pulling my attention to the music and not the work I was doing.
It really caught my attention when Lou Reed's New Sensation was playing. A love story of a man and his Kawasakit GPZ motorcycle, the guitar chords were so pleasant to listen to. That is my initial impression, how pleasant!
At the end of the session, I heard more hum than I heard when first started, could be my work area stereo or the "reference quality" turntable I use in the work room.
It really caught my attention when Lou Reed's New Sensation was playing. A love story of a man and his Kawasakit GPZ motorcycle, the guitar chords were so pleasant to listen to. That is my initial impression, how pleasant!
At the end of the session, I heard more hum than I heard when first started, could be my work area stereo or the "reference quality" turntable I use in the work room.
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I finished my MM version of the FS NJFET preamp. After I got over the initial thrill of having it play music from both channels at the same time, I spent the next four hours listening. Every couple of songs, I would stop working just to listen, I was surprised at how it kept pulling my attention to the music and not the work I was doing.
It really caught my attention when Lou Reed's New Sensation was playing. A love story of a man and his Kawasakit GPZ motorcycle, the guitar chords were so pleasant to listen to. That is my initial impression, how pleasant!
At the end of the session, I heard more hum than I heard when first started, could be my work area stereo or the "reference quality" turntable I use in the work room.
Can't be sure form the photos, but the PSU box must also be linked to the mains protective earth if not, I can see the RAW DC board is linked, also check there is proper electrical continuity between all the phono box panels and the TT lug where the boards signal earth connects. Painted or anodized surfaces can remain isolated if screws aren't making the continuity. Some surface scratching at points of contact between panels or non anodized screws can do the trick if so. I read that the SL-5 can be noisy at times depending on its state of contacts but inspect the above about the boxes earthing status anyway.
OK. The umbilical power chord's shield is good to be connected with the PSU chassis too I forgot to mention. But left unconnected on its other end to the phono chassis. By the way, what value C2Y you used?
150 pF ROHM polystyrene supplied by Teabag in the kit. He also included a WIMA 250 pF, which I did not use, yet.
The umbilical cord has the shield connected to the P/S, but not the preamp.
The umbilical cord has the shield connected to the P/S, but not the preamp.
All well then. If the treble amount seems natural in your system don't try another C2Y value. But keep the WIMA to can try in case of a bright cart or speakers in the future.
Hello Salas - I found the cause of the hum, I did not have a connection to the chassis from the mains safety ground. I had the mains safety ground connected to the power supply board, but not the chassis, small wire from safety ground to chassis and all is quiet.
In regards to C2Y, increased capacitor value decreases the treble?
So if I was to remove the 150 pF C2Y, then the preamp would be brighter sounding?
I want to be sure about C2Y so I can add the info to my notes for the future.
In regards to C2Y, increased capacitor value decreases the treble?
So if I was to remove the 150 pF C2Y, then the preamp would be brighter sounding?
I want to be sure about C2Y so I can add the info to my notes for the future.
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