Would this mean my measuremant at RCA jack is faulty? Otherwise, yes, like Formosawest I am showing a few Mv....If I am not measuring offset correctly, please advise. I assumed what is on the output jack is what would matter.
Is this safe to hook up? I wish I could be more certain of the mosfet, I hate to mess up board with desoldering, especially not knowing what blew them!
concerned about DC at output, if I am measuring correctly...
Russellc
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Tried it with Ortofon, music come out undistorted, but loud hum. I know this is fixable at least. To tired tonight, will post pics tomorrow. I do have BA-3 pre right next to it, but this sounds like something isnt grounded.
Last experiment tonight is moving preamp further away...dont think thats it.
Pics tomorrow.
Russellc
Last experiment tonight is moving preamp further away...dont think thats it.
Pics tomorrow.
Russellc
Well I will be dipped if it wasnt the close proximity of the BA-3 pre. Playing wonderfully now.
6L6, tell me, would the blank hole for C22 be a good place for the snubber?
Its small but it looks on the schematic to be in the correct place.
Listening before bed!
Oh, and it is DEAD quiet
Russellc
6L6, tell me, would the blank hole for C22 be a good place for the snubber?
Its small but it looks on the schematic to be in the correct place.
Listening before bed!
Oh, and it is DEAD quiet
Russellc
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Hi Russellc,
Can you comment on this? How far was the BA-3 from the Pearl2 when
you had the hum and how far you eventually moved it for the hum
to go away?
I'm wondering if it means one might have problem stacking
components.
Thanks,
Dennis
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Mine is in a DIY store chassis. I think some parts are steel, some aluminum. They were so close they may have been touching. This morning I played with it a little, and it is working quietly beside, but about 8-10 inches from the BA-3...it is also in a DIYstore chassis. This thing is dead quiet. No hiss, no hum, dead quiet. I have not tried it with my more efficient speakers, but I heard nothing even with ear right to speaker.
This thing is WAY sensitive (in terms of offset) to any air currents, breath, even through vents. My regulators (at least when I tried them after a few mins. of play were just warm, so I blocked off the vents...I will recheck today after extended play for temp. If it stays like it was, I may seek a non-vented "lid".
Note: dont try to adjust it under a ceiling fan like I did, you will get nowhere except freaked out.
When it was too close, there was a very pronounced HUM. You could hear music underneath, but buried by hum. I figured just a ground problem I would solve later today. I moved it on a lark before bed, and dead silence...which lead to me staying up way later than I should have!
Russellc
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Ha - Sounds like the first time I tried setting offset on my Aleph-X amps. Or repairing an old tube radio under a set of fluorescent light bulbs ....
..which lead to me staying up way later than I should have!
A sure sign of a well-executed project! Glad to hear the solution was so "simple."
Long story made short - if you want a Pearl or Pearl 2 truly, genuinely quiet, it has to be at least 3 feet (1M) away from any transformer.
This has also been true with every phonostage I've built. (5)
That's good to keep in mind. And to follow up on Eric's point, I too am
wondering if a steel chassis might be better in this application.
I do wonder, how does something like the XP-15 do it? I wonder what
kind of shielding techniques are used.
How long an umbilical would be too long? Can one get away with 2m?
For some strange reason, these issues being mentioned are getting
me even more interested in building this now...
Dennis
I have a noise microscope -- it's called a pair of efficient headphones and the O2 headphone amp. With the gain full open on the O2 there's no perceivable noise. Plug it into a phonostage and you can hear everything... much more noise/hum/etc. than just ear to speaker.
To get induced hum completely inaudible, (assuming it's wired correctly) quiet down to where you only hear the popcorn noise of the input Jfets, you need to have it 3ft from any transformer.
To get induced hum completely inaudible, (assuming it's wired correctly) quiet down to where you only hear the popcorn noise of the input Jfets, you need to have it 3ft from any transformer.
That's good to keep in mind. And to follow up on Eric's point, I too am
wondering if a steel chassis might be better in this application.
I do wonder, how does something like the XP-15 do it? I wonder what
kind of shielding techniques are used.
How long an umbilical would be too long? Can one get away with 2m?
For some strange reason, these issues being mentioned are getting
me even more interested in building this now...
Dennis
My umbilical is just a smidge longer than 5 feet.
Russellc
I've just started a Pearl 2 build - and this thread has helped quite a bit. Couple of questions that I'm hoping you all might be able to help me out with. This project will be only my second DIY electronics adventure, so please bear with me.
1) It looks as though there are several components where onemay want to swap values depending on the cartridge being used. In various threads I've seen suggestions for using "sockets," DIP switches, or rotary switches to allow for this swapping. I don't plan to change cartridges with great frequency, but I would like to be able to make a change without having to desolder things. The DIP/rotary switches are more advanced than I would like to attempt at this point in my DIY career - I just want to get things working before complicating things. So can anyone give me any guidance (pictures, Mouser parts numbers, etc.) on what I should use to be able to swap out resistors/capacitors? Can I just use a female header (I guess i would have to clip some of the pins so that it would fit on the board?) like you find on the Arduino? I think the pin spacing would work ...
Or would something else work better?
2) What are the components that I might want to tweak? Based on the threads I've read, the following all seem like candidates:
R14 --> alter gain
R19 --> cartridge loading
R20 --> cartridge loading
C12 --> reduce subsonic roll off
C22 --> change capacitance for cartridge
Any others?
1) It looks as though there are several components where onemay want to swap values depending on the cartridge being used. In various threads I've seen suggestions for using "sockets," DIP switches, or rotary switches to allow for this swapping. I don't plan to change cartridges with great frequency, but I would like to be able to make a change without having to desolder things. The DIP/rotary switches are more advanced than I would like to attempt at this point in my DIY career - I just want to get things working before complicating things. So can anyone give me any guidance (pictures, Mouser parts numbers, etc.) on what I should use to be able to swap out resistors/capacitors? Can I just use a female header (I guess i would have to clip some of the pins so that it would fit on the board?) like you find on the Arduino? I think the pin spacing would work ...
Or would something else work better?
2) What are the components that I might want to tweak? Based on the threads I've read, the following all seem like candidates:
R14 --> alter gain
R19 --> cartridge loading
R20 --> cartridge loading
C12 --> reduce subsonic roll off
C22 --> change capacitance for cartridge
Any others?
I've just started a Pearl 2 build - and this thread has helped quite a bit. Couple of questions that I'm hoping you all might be able to help me out with. This project will be only my second DIY electronics adventure, so please bear with me.
1) It looks as though there are several components where onemay want to swap values depending on the cartridge being used. In various threads I've seen suggestions for using "sockets," DIP switches, or rotary switches to allow for this swapping. I don't plan to change cartridges with great frequency, but I would like to be able to make a change without having to desolder things. The DIP/rotary switches are more advanced than I would like to attempt at this point in my DIY career - I just want to get things working before complicating things. So can anyone give me any guidance (pictures, Mouser parts numbers, etc.) on what I should use to be able to swap out resistors/capacitors? Can I just use a female header (I guess i would have to clip some of the pins so that it would fit on the board?) like you find on the Arduino? I think the pin spacing would work ...
.
Or would something else work better?
2) What are the components that I might want to tweak? Based on the threads I've read, the following all seem like candidates:
R14 --> alter gain
R19 --> cartridge loading
R20 --> cartridge loading
C12 --> reduce subsonic roll off
C22 --> change capacitance for cartridge
Any others?
I would have no idea. But the builds with the most trouble seem to be where members build outside the standard plan. For me, and I can only speak for myself, I would build it as designed and getting it working first, then try all these esoteric switching ideas. If you have problems with the build, you have a lot more possibilities for causing them. If you build standard and it works, its just a matter of adding the ideas you have. Then if there is a problem, you know it concerns the addition, not the basic circuit. Just my 2 cents, your experience level my be far beyond mine and you are perfectly comfortable going full tilt with all that switching and so forth.
Russellc
The short answer is that I've currently got some MM cartridges designed for DJ use, but I will probably be switching to an MC cartridge (Denon DL-103) or to a "fancier" MM cart.
The long answer:
I've got a Technics 1200 M3D (two of them, actually) with a variety of Ortofon and Shure cartridges that I picked up during my DJ days - Ortofon Concorde Nightclub, Shure Whitelabel, etc. All this stuff has been in storage for years during a major home renovation. And I hadn't really seriously listened to vinyl for a few years before that. I had pretty much switched entirely over to the digital domain - the one other DIY project I've done is the Buffalo IIISE DAC. But in the course of unpacking I found my records and turntables and thought I'd give the analog world another shot.
My first thought was to "upgrade" to a VPI Classic, but I decided it was worth giving my 1200s a chance first. That got me looking for mods and I found a thread you (6L6) wrote about rewiring a Technics. That rewire is in progress (forgot to order the tonearm cables when I ordered the RCA cables and PCB). I was then planning to upgrade the cartridge on one of the tables to a Denon DL103, an Ortofon 2M Blue, or an Audio-Technica 440MLa (or others - am open to suggestions).
Reading your post on rewiring the Technics led me to the Pearl 2. The plan is to then tackle the B1 (maybe adding in AMB's d1/d2/LCDuino in front of the B1 for volume control and source switching, if I'm feeling really ambitious).