Search found 1018 matches
- Mon Feb 20, 2023 5:56 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 58544
Re: It's time I built a D3a -> 5687 phonostage
So post-RIAA I go a bit off-piste: https://user.fm/files/v2-9fe738e8842bcf5d04640679e3bb6961/Screenshot%202023-02-20%20at%2017.48.33.png I was looking at the output stage of Stephen's (izzy-wizzy) circuit and couldn't help noticing a similarity to Lynn Olson's Raven . This is a version of that, with...
- Mon Feb 20, 2023 2:48 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 58544
Re: It's time I built a D3a -> 5687 phonostage
Fixed it! Found a model on https://www.diyaudio.com/community/threads/xys-ixtp08n50d2-and-ixtp08n100d2-ltspice-model.307318/ which makes use of the VDMOS model, pasted it into standard.mos and I was able to pick it as a transistor. Sim seems to work now, I get about 44dB gain before it hits the RIAA...
- Mon Feb 20, 2023 2:20 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 58544
Re: It's time I built a D3a -> 5687 phonostage
What you have missed is the line that says that the depletion mosfets are IXTP08N100's I just used the 740 models as they have the same pinout. The mosfet that's driving the d3a g2 is a STU3N45K3, but most high voltage N chan will be fine there I just wanted one with a low Cgs Ahhhhh... like footpr...
- Mon Feb 20, 2023 1:18 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 58544
Re: It's time I built a D3a -> 5687 phonostage
Thanks Nick. Well, this is frustrating. I've laid out the first stage in Spice so that I can study the circuit and work out what's going on. Unfortunately, I'm getting next to no gain (in fact it's a loss), there's almost nothing on the 5687 cathode. The current going through the first two MOSFETS i...
- Sun Feb 19, 2023 7:45 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 58544
Re: It's time I built a D3a -> 5687 phonostage
My search foo is good today! Though I see some battles with Spice on the horizon... Thanks Mark - that image is a bit clearer. The only thing I still cannot make out is the value of the two caps in parallel going to the three pin connector from the 5687 cathode (which I presume is the interface to t...
- Sun Feb 19, 2023 2:55 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 58544
Re: It's time I built a D3a -> 5687 phonostage
Found it: Link
Wow... that's interesting...
Yeah, that looks DIY-feasible. How hard can it be?
Time to knock up a Spice sim...
Wow... that's interesting...
Yeah, that looks DIY-feasible. How hard can it be?
Time to knock up a Spice sim...
- Sat Feb 18, 2023 6:17 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 58544
Re: It's time I built a D3a -> 5687 phonostage
This was what I had in mind for stage 1:
To the right of the RIAA, probably an interstage?
Will hunt around for Nick’s arrangement too.
To the right of the RIAA, probably an interstage?
Will hunt around for Nick’s arrangement too.
- Sat Feb 18, 2023 3:10 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 58544
Re: It's time I built a D3a -> 5687 phonostage
Seems to me that one obvious way to get around the low impedance input to the RIAA is to use a step-down interstage in front of it. Though if I were to go for a hybrid solution, an op-amp may be much cheaper. Have you considered Nick's method and rejected it ? I'm just a bit concerned about transpa...
- Sat Feb 18, 2023 12:02 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 58544
Re: It's time I built a D3a -> 5687 phonostage
I thought you had cinemag lcr units in the one you built, could you not take those out instead of shelling out for the sowters? The s&b ones in my cole are 600r ones iirc, are there different impedance ones available? I always wondered why 600r which seems a little bit of a strange value, but i...
- Fri Feb 17, 2023 10:09 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 58544
Re: It's time I built a D3a -> 5687 phonostage
Right then. I've decided to be ambitious. So Sowter make the 1280 RIAA 600 Ohm EQ Unit - an off-the-shelf RIAA EQ similar to the classic Tango units. I'm keen to design a circuit around that. Ha! as if I know anything about phono stage design. But I really like what the Pete Millett LR does, so I wa...
- Wed Feb 15, 2023 4:12 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 58544
Re: It's time I built a D3a -> 5687 phonostage
I've had to go back to the Whest stage for the moment whilst I try and get the LR stage fixed. Whilst I can hear its full bandwidth, I immediately missed what the LR stage was doing in the midrange (as heard at Owston) despite its response anomalies. The Whest just isn't as good. I don't know how mu...
- Wed Feb 15, 2023 12:15 am
- Forum: Everyones Projects
- Topic: AMB linestage rebuild
- Replies: 68
- Views: 40489
Re: AMB linestage rebuild
Well Dave, obviously, as you are aware, it takes a great deal of blood, sweat and tears to produce work of such incredible shoddiness. :D I wouldn’t know where to start with that stuff. Thanks Steve - over a year's worth of blood, sweat and tears in fact, looks like I started this thread last Janua...
- Tue Feb 14, 2023 4:27 pm
- Forum: Everyones Projects
- Topic: AMB linestage rebuild
- Replies: 68
- Views: 40489
Re: AMB linestage rebuild
OK, it's done. That was quite possibly the hardest thing I've ever designed. Interior picture before the lid went on: https://user.fm/files/v2-b5cc1e6d69b2421c5d52cb89db835b93/completed_interior.jpg Front panel (getting the blackout film stuck on behind the perspex was a lark): https://user.fm/files...
- Thu Feb 09, 2023 7:21 pm
- Forum: Everyones Projects
- Topic: It's time I built a D3a -> 5687 phonostage
- Replies: 78
- Views: 58544
It's time I built a D3a -> 5687 phonostage
I have a hankering to try a good valve phonostage again, and having read through several threads here, and on Hi-Fi Haven, we seem to quite regularly come back to the D3a for stage 1, and more often than not a 5687 for the second stage, to get really good results. Yesterday I impulse bought a couple...
- Mon Feb 06, 2023 8:04 pm
- Forum: Valves
- Topic: What are the oldest affordable valves you can still buy?
- Replies: 13
- Views: 8856
Re: What are the oldest affordable valves you can still buy?
Yes, that’s part of it.IslandPink wrote: ↑Mon Feb 06, 2023 5:56 pm Do you need to look into different equalisation curves ?