Search found 1018 matches
- Sat Mar 04, 2023 4:04 pm
- Forum: Assorted Stuff
- Topic: Nothing In Particular
- Replies: 16489
- Views: 4856126
Re: Nothing In Particular
Downloaded and installed KiCad 7 to my desktop and getting it sorted out so that it's ready to go for the next project. I have to say, much as I love it, the library management protocol is terrible, especially if you are trying to configure it to be usable with a cloud drive across more than one dev...
- Mon Feb 27, 2023 8:02 am
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 59826
Re: It's time I built a D3a -> 5687 phonostage
That's rather adventurous. The paradise was a bjt version of the same idea and certainly sounds good. I think PCB layout will be a big part of the work. I do note that the article suggests that the first stage can drive <600 but that's far from saying that it should. They then load it with a 20k ne...
- Sun Feb 26, 2023 1:40 pm
- Forum: Everyones Projects
- Topic: Pete Millett LR phono preamp
- Replies: 39
- Views: 23749
Re: Pete Millett LR phono preamp
Well, I've managed to get the response a lot flatter than before. I got my Spice sim of the circuit up and started to experiment to see if dropping any of the resistor values would act to bring up the missing top end. Practically, this would mean I'd only need to solder an additional resistor in par...
- Sun Feb 26, 2023 9:41 am
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 59826
Re: It's time I built a D3a -> 5687 phonostage
Okay, so after much pondering I've decided to take a chance and go down the current-input route with the Proteus circuit (Erno Borbely and Sigurd Ruschkowski, Linear Audio Vol 6, Sept 2013), but with LCR RIAA lovelyness in the middle. From the research I've done, it has a very good chance of working...
- Sat Feb 25, 2023 8:22 am
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 59826
Re: It's time I built a D3a -> 5687 phonostage
Depends on the cartridge. It's not a totally universal solution and only for MCs. A bunch of commercial stages do this. I think my current cartridge is about 16 ohms coil impedance, but the one I'm buying this year has a coil impedance of about 3 ohms. Seems ideal to me. Naturally I'm doing lots of...
- Fri Feb 24, 2023 11:47 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 59826
Re: It's time I built a D3a -> 5687 phonostage
Not discounting any design options at this stage (cos I still effectively have a clean sheet) I'm currently studying a Linear Audio article I purchased a couple of years ago with a current input design for MC cartridges, where you get around the need for a step-up transformer by taking advantage of ...
- Fri Feb 24, 2023 8:20 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 59826
Re: It's time I built a D3a -> 5687 phonostage
I feel that as the availability of a lot of these things tends to zero many of the traditional choices and designs will become impractical. This is why I'm still periodically getting cold feet over this - I don't want to put a whole heap of effort and expense into something that I can't use after 5...
- Fri Feb 24, 2023 3:19 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 59826
Re: It's time I built a D3a -> 5687 phonostage
Forget the number but there is a Russian high GM pentode that works as well. But I remember measuring some and finding two sets of curves as if there were two construction types. Yeah, the 6J52P - I think I saw a post from Kevin of K&K Audio mentioning those, that he also found them all over th...
- Thu Feb 23, 2023 10:21 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 59826
Re: It's time I built a D3a -> 5687 phonostage
Rated to something like 10k hours IIRC?
- Thu Feb 23, 2023 1:34 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 59826
Re: It's time I built a D3a -> 5687 phonostage
Ha ! How about £25 each nowadays ? I should have bought more :roll: More than that, at least the two I've bought were. And this is a perennial worry because I didn't get in when they were cheap. I found some NOS Siemens for sale from a Netherlands supplier at a reasonable price that seemed perfect,...
- Thu Feb 23, 2023 1:14 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 59826
- Thu Feb 23, 2023 1:20 am
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 59826
Re: It's time I built a D3a -> 5687 phonostage
I don't think I'm going to lose too much sleep over the cap coupling - the Spice model is suggesting that whilst the LF rolloff will occur earlier, it's still tolerable. I still have 4 big 47uF Obbligato film caps kicking around from an abandoned project years ago, I might press those into service. ...
- Wed Feb 22, 2023 10:14 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 59826
Re: It's time I built a D3a -> 5687 phonostage
I guess you could use a interstage, but again I think you are assuming the problem exists that needs a solution. I guess you could use a small cap into a high impedance buffer such as a op amp with voltage protection clamps on its inputs. Now there's an idea, I think the OPA161x series that I used ...
- Wed Feb 22, 2023 7:23 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 59826
Re: It's time I built a D3a -> 5687 phonostage
I guess you could use a interstage, but again I think you are assuming the problem exists that needs a solution. I guess you could use a small cap into a high impedance buffer such as a op amp with voltage protection clamps on its inputs. Now there's an idea, I think the OPA161x series that I used ...
- Wed Feb 22, 2023 5:32 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 59826
Re: It's time I built a D3a -> 5687 phonostage
So with a 600R termination it looks like those values need to go up a bit.IslandPink wrote: ↑Tue Feb 21, 2023 6:38 pm Yes, of course, i asked you similar questions when I first saw the circuit.
So that's the reason for the 2 x 33uF caps from the 5687 CF - to get a low time constant with the 1.5K termination.