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AUDIO FORUMS >> D.I.Y. >> Glassware Phono pre Project
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Message started by 4krow on 09/01/21 at 11:52:45

Title: Glassware Phono pre Project
Post by 4krow on 09/01/21 at 11:52:45

Some time ago, I started the phono pre project which was designed by Pete Millett. It was an LR design, and I was curious as to what it might sound like. Unfortunately, the key inductors were not available for months, so the decision was made to start a mew phono pre project by John Broskie. It is much more expensive and uses 2 power transformers, 8 EC81 tubes, and takes up a lot of space, requiring a full sized chassis. Here is what I have so far. The boards are very sturdy and thick. The parts are not skimped anywhere. In a couple of weeks I will have the chassis drilled and ready to go.https://ibb.co/GQ6sC1j
https://ibb.co/hMbxB6v

Title: Re: Glassware Phono pre Project
Post by EdwardT on 09/01/21 at 12:44:29

Is that massive power supply FET regulated?

Title: Re: Glassware Phono pre Project
Post by 4krow on 09/17/21 at 02:49:08

What I do know is that the power supply uses 4 LD1085 voltage regulators (I think FET?), and an IXCP 10M45S High voltage constant current source. The 8 tube filaments use a bunch of current (240ma), whereas the high voltage supply (240 VDC) only needs about 45-50 ma.

Title: Re: Glassware Phono pre Project
Post by Dana on 09/17/21 at 16:24:17

That's beautiful. How does it sound?

Title: Re: Glassware Phono pre Project
Post by 4krow on 09/17/21 at 20:36:32

Thanks. Dude, I am gritting my teeth awaiting the last parts to arrive today! Got just a bit more drilling to do on the rear panel and then the final AC work can begin. The power supply is fine and the tubes light up, so there is that. I just want to get all the ducks in a row before takeoff.

FWIW, Mr. Broskie's designs are simply great. Only point to point wiring and a tube based rectifier would help.

Title: Re: Glassware Phono pre Project
Post by Stefan on 09/18/21 at 05:24:06

Looks great! Looking to upgrade my phono preamp soon as well, this looks interesting… how much are the parts roughly?
And looking forward to hear how it sounds!

Title: Re: Glassware Phono pre Project
Post by EdwardT on 09/18/21 at 16:43:19

Very nice, those LD1085s have a reputation of being very consistent and that’s exactly what you want for a phono preamp.

Title: Re: Glassware Phono pre Project
Post by 4krow on 09/18/21 at 21:04:05

Stephan, I may finish today. Always waiting for epoxy to cure or glue to dry, or paint to look good. I will assemble in a minute or two and then send along photos.
FWIW, look to spend about 1k$ for a project like this. I didn't want to go that deep, but my previous phono project just couldn't happen when the parts got scarce. It was kind of a cruel joke that those parts arrived two days after I ordered this kit! Ended up trading the first phono project to a friend, and built this one.
Ed, Yes Mr. Broskie has it together all the way with his products. My only concern is when I don't fully understand which part to choose when it comes to custom application.

Title: Re: Glassware Phono pre Project
Post by 4krow on 09/18/21 at 21:36:19

Ok so, here is the idea of this build. Why are the inputs on the side? Because it creates a much shorter path away from other electronics. Why are there two ground posts? Because I don't know yet. I will find out when the build is being tested. What would I do different? Damned good question. TBD after use.
https://ibb.co/DtM5QKb
https://ibb.co/gvcTsv1

Title: Re: Glassware Phono pre Project
Post by Stefan on 09/19/21 at 22:56:56

Thanks for the infos 4krow! Looks very professional. I hope it sounds as good too :)

Title: Re: Glassware Phono pre Project
Post by 4krow on 09/19/21 at 23:18:08

Stephan thanks, it was more work than I normally put into a unit. AND well, one channel sounds good, but there is a bad hum in the other. Yup, something that I did somewhere concerning a grounding issue. That is one thing that I appreciate about stereo, and that is you may have a reference if the trouble is only in one channel.

Title: Re: Glassware Phono pre Project
Post by 4krow on 11/10/21 at 19:53:46

I'll be short and say that this pre went to a really good tech for repair probably due to a mistake that I could not find. So far, neither can he. crap. In the meantime, I was successful at building a phono preamp designed by Pete Millett. It also had issues at first but they have been straightened out. FWIW, the sound is quite superior to the Vincent PHO8 that I was using before. Man, this TT stuff has taken forever to get right. I am still convinced that the cartridge or maybe connection of tonearm cable is not optimal. Who knows, someday I will have the TT sounding as it should. I am about 70% of the way there so far.
Got a shot of the PM phono board here:

https://ibb.co/rQDKW2N

Title: Re: Glassware Phono pre Project
Post by Stefan on 11/14/21 at 04:57:44

DIY is fun, but always full of pitfalls, very rarely my projects work out perfectly in the first try...
Hope you will get all the issues strengthen out and get your sound from 70% there to 110% ;)

Title: Re: Glassware Phono pre Project
Post by 4krow on 01/11/22 at 04:39:42

This build was in honor of my father's contribution to music. It Finally turned out stupendous. No noise, no hum, but just the finest sounding Phono pre that I have heard out of the 5 that I have owned.

Thanks, dad, for the music.

https://ibb.co/12WHhJt

Title: Re: Glassware Phono pre Project
Post by DA6469 on 01/11/22 at 17:31:14

4krow,

Nice work!