Bigman80
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Post by Bigman80 on May 17, 2020 18:48:06 GMT
Sorry, should have read 3081 and 3091 I will investigate! |
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Bigman80
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Post by Bigman80 on May 22, 2020 8:01:18 GMT
The new JFET pcbs have just landed.....my word they are small lol Gonna get a pair built and plumbed in to my BB3 today and see what the crack is.    |
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Post by firebottle on May 22, 2020 8:08:48 GMT
Then you'll know what I have been banging on about  How many resistors have you got lined up, 30? |
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Bigman80
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Post by Bigman80 on May 22, 2020 8:09:24 GMT
Then you'll know what I have been banging on about How many resistors have you got lined up, 30? I have 20 I think, and I'll need 16.. Why, need some? |
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Post by firebottle on May 22, 2020 8:10:52 GMT
2:5 ratio, should just about work.  Aah, you're assembling 4 boards, bit more of a challenge. |
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Bigman80
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Post by Bigman80 on May 22, 2020 8:14:04 GMT
2:5 ratio, should just about work. Aah, you're assembling 4 boards, bit more of a challenge. Yes, possibly 3 sets!! |
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Bigman80
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Post by Bigman80 on May 22, 2020 8:44:30 GMT
Resistors on PCB1 Christ....its tense stuff this lol So far, ZERO resistors have been lost  |
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Bigman80
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Post by Bigman80 on May 22, 2020 8:52:24 GMT
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Bigman80
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Post by Bigman80 on May 22, 2020 9:13:29 GMT
Finished......nowbto lie down somewhere while my eyes recover lol 1 pair of matched multifet boards. Cool Now to fit them!  |
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Bigman80
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Post by Bigman80 on May 22, 2020 10:35:39 GMT
Look rather cool! But they aren't working..... bollocks   |
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Bigman80
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Post by Bigman80 on May 22, 2020 12:47:56 GMT
So at the moment, the left channel is out of action and theres little to no gain.
I'm now at Alan's (social distancing adhered to) who tells me I've broken my PCB lol
I'm not even nearly surprised as I've molested the life out of this PCB with experiments etc.
If we can demonstrate the PCB working with the little multifet boards, and everything measures ok, I'll end up rebuilding my phonostage AGAIN!!!!!
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Post by electronumpty on May 22, 2020 13:13:15 GMT
Finished......nowbto lie down somewhere while my eyes recover lol 1 pair of matched multifet boards. Cool Now to fit them! Are we gonna have to call you Squintman80 now? they look good hope you get them working. |
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Post by sq225917 on May 22, 2020 14:14:48 GMT
Time for some 0.3mm solder and liquid flux fella.
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Bigman80
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Post by Bigman80 on May 22, 2020 14:51:29 GMT
Its the FETs by the looks of it
The BF862 Alan uses look to be ok, but the BF861C I use do not want to play ball. Seems they don't like being paired up as they remove all the gain.
The BF862 behave differently and appear to react really well to being paired up.
This is a major pisser, as the BF862 are no longer stocked anywhere.
We're going to try some BF861A, which Alan thinks may behave like the BF862
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Deleted
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Post by Deleted on May 22, 2020 15:08:45 GMT
The "C" isn't that far from an 862 is it? Might want some "Bs" on hand if the "A" goes too far the other way  |
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Bigman80
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Post by Bigman80 on May 22, 2020 15:26:53 GMT
The "C" isn't that far from an 862 is it? Might want some "Bs" on hand if the "A" goes too far the other way Yes, great point Scotty. Alan is going to give the data sheets a once over and see what's the best match. I'm not keen on having to order Fets from China. |
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Deleted
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Post by Deleted on May 22, 2020 15:29:12 GMT
They're in stock at Farnell, it's where I got my bits from.
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Post by firebottle on May 22, 2020 16:03:04 GMT
861B's it is comparing the data sheets.
Whoever said the 861C was close to the 862 didn't look too closely at the data sheets.
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Deleted
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Post by Deleted on May 22, 2020 16:09:58 GMT
I said "isn't that far" and looked closer than the A and B variants from the quick look I did have..... But hey ho
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Bigman80
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Post by Bigman80 on May 22, 2020 16:43:10 GMT
I said "isn't that far" and looked closer than the A and B variants from the quick look I did have..... But hey ho No, originally! We swapped the 862 for 861c a year or so ago.....our fault, we should have checked... Too trusting |
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Bigman80
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Post by Bigman80 on May 22, 2020 18:46:09 GMT
It's been a long ass day.
I started about about 08:45am and i am only 1 side into a piece of vinyl at 19:33!
What started out with huge optimism, descended into despair and has finally ended in relief, that all of the pissing about today had shown another step forward.
Alan recognised that after MULTIPLE experiments around the FET setup, i had finally found the breaking point of the PCB's through holes and had a short. He then discovered that the FETS (BF861C) would not play ball if we paired them up. After 2 trips to Alan's and one trip to mine for Alan, I finally have working multifet boards.
They currently have BF862 from China in there, no doubt counterfeit as they have been discontinued for a long time now, but they sound fantastic. So the all important question was "do the boards reduce noise?"
Yes they do.....rather noticeably.
I have rebuilt my phonostage with the torroid in the same box as the PCB to save time, and i can hear a very feint hum, which 100% was not audible before. Admittedly, the 862 fets have a bit more gain than the 861C so maybe they are having an influence there.
I will order some BF861B which Alan has identified as being a closer match to the original BF862 that we used once upon a time, and try them on the Multifet board!
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Post by electronumpty on May 22, 2020 20:29:49 GMT
Got to admire your perseverance here well done. Sounds like it will make a difference too so worth the pain.
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Post by rexton on May 22, 2020 20:34:27 GMT
At least it's up and running now.
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Bigman80
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Post by Bigman80 on May 22, 2020 20:38:10 GMT
Got to admire your perseverance here well done. Sounds like it will make a difference too so worth the pain. It's a group effort! But I am a little frustrated as I am a big fan of the sound the 861c produces If Alan can get the 861B to work how we want it to, then I strongly suspect that it will have been worth all the aggravation. |
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Bigman80
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Post by Bigman80 on May 22, 2020 20:38:30 GMT
At least it's up and running now. Up and running and sounding mighty fine! |
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Post by rexton on May 23, 2020 7:30:38 GMT
At least it's up and running now. Up and running and sounding mighty fine! Oli, can you PM me some details of costings for the BB3 please. |
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Bigman80
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Post by Bigman80 on May 23, 2020 7:32:49 GMT
Up and running and sounding mighty fine! Oli, can you PM me some details of costings for the BB3 please. Sure. |
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Bigman80
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Post by Bigman80 on May 26, 2020 10:53:10 GMT
Seems my desire for a high voltage, 6 core cable cannot be realised. Oddly, its 5 or 6 core on the menu. Strange 7 core OLFLEX it is then.  |
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Deleted
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Post by Deleted on May 26, 2020 13:03:30 GMT
Is that 0.5mm per conductor and are you buying a reel of it?
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Bigman80
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Post by Bigman80 on May 26, 2020 13:06:35 GMT
Is that 0.5mm per conductor and are you buying a reel of it? No its 1m unfortunately...I'll pick a few strands out to make it fit the solder buckets. Only ordered 3m of it. Guy on ebay is doing it by the meter |
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