Type 1272 Preamp with JLM Hotrod Mod and BA283AV (Pics)

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Greg

Well-known member
Joined
Jun 7, 2004
Messages
1,784
Location
New Orleans, LA
It's taken me a while to get this finished, but it's up and running and sounds great. Thanks to Joe for the Hotrod Mod, and a VERY special thanks to this forum for the transformers. I won these transformers in the student Thanksgiving giveaway year before last. This allowed me build a pair of fantastic preamps for a fraction of the cost.

It took me nearly two years to put these transformers into action, but at the time I knew nothing about Neve circuits... so I put them on the backburner until I got my wits together.

Some details:
- BA283AV are DIY from Fabio's boards
- Hotrod Mod circuit by JLM Audio
- Sowter I/O transformers.
- JLM Go-Betweens and DI
- Modified Fabio 312 PSU (+24VDC and +48VDC only)

1272_Angle.JPG


1272_Front.JPG


1272_Channels.JPG


1272_Top2.JPG


Fool.JPG

I Pitty Da' Fool
 
Well done, Greg. Looks great.

Does that combination make the "classic" N*eve preamp? I've never taken the time to figure out which board is which, etc.

Roddy
 
wow that looks great :thumb: I also see the JLM DI go between right? very cool.... simple clean and you could probably add another 2 channels into that case as there is much room...
 
Nice one, Greg. Neat wiring, clean layout. I'm building a pair of 1272 things using Fabio's N72 boards and plan to use Sowter in and Lynx out. I'm curious what you think of the sound of these with the Sowter in.

:guinness:
A P
 
I don't know what's better, the killer DIY handywork, or the awesome self-portraits. On both fronts, once again, well done! :green:
 
Thanks for all the compliments on the wiring... I really do like to take my time with the wiring. It always makes working on it in the future easier if something goes wrong.

@rodabod: I'm wouldn't describe my particular combination as "classic" Neve, mainly due to my choice of transformers and lytics on the Hotrod Mod board (Nichicon PW). I did use BC components lytics and polystyrene film caps on the BA283AV, but I used a modern 2N3055. It does have the Neve mushy,rich, low midrange thing going on... but it has a more extended top-end than the other Neve stuff I've heard.

@AP: I feel the Sowters extend the higher frequencies a bit, but I like it. This could be a bad thing if tracking guitars, but I love what it does on my voice in particular.

@pucho812: Yes, Go-Between with DI on Channel 'A' and Go-Between without DI on Channel 'B' ... come to think of it, I didn't test the DI yet, DOH !!!

@Tillmann: I'm only an EE by day... general audio nut by night :shock: . But most EEs (at least the ones I went to school with) absolutely hate circuits, electronics, and the like. It was quite odd. Come to think of it, most of them hated every class... but I guess most of them make decent money by now, so mission accomplished as far as they're concerned.
 
Greg that looks killer!! I have been doing the PSU's externally on my Neves for hum reasons, but I'd love to put the PSU inside (saves the $26 for a PSU box). Are you picking up any hum with this layout? Also, is that an Amveco "Mini" Toroidal? Thanks, Martin
 
No, I'm not picking up any audible hum... at least not on a set of nearfields. I'm going to run some RMAA tests soon to see what shows up on the spectrum, then perhaps hook it up to a system with a subwoofer just to see if there's anything swirling down there.

Regarding power transformer, I'm now using Avel Lindberg... exclusively. I prefer them over Amveco !
 
Hey Greg,

Looking sharp! Well done, Very neat work indeed. I'm sure you will love them. I'm enjoying my pair and thanks again for taking on the PCB layout, very neat and was a great help in completing the project.

Cheers

Matt
 
Nice Greg! Very tidy. One day I'll put mine together. It's pretty much at the back of the line. :oops: But your finished unit serves as some great inspiration.
 
Nice work. Hope mine end up even half as nice. What is the mfg number on the toroid? Would that power 4? Would I need another AC/DC from Joe? Thanks.
 
hi greg,
nice, clean build! :thumb:
hopefully i'll be able to work on my 1272 with your hotrod boards soon too. quick question(s), if you don't mind, how does that "over-the-top" heatsink work on the 2N3055? does it work as well as the old school neve heatsink platform thing?
thanks.
-grant
 
cjs2k:
www.avellindberg.com
I think I ordered the Y236105, which is 22-0-22 @ 30VA

I don't know the exact current from each channel of 1272, nor did I measure it. I don't think it would be more than 200mA per channel (probably lower), so 30VA is plenty. Assuming 200mA per channel with 4 channels, I might step it up to their next size, which I think it 50VA. If we knew the exact current draw we could nail it down.

@dissonantstring
Both heatsinks work well... no problems either way !

:guinness: :thumb:
 

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