Custom M125's

I thought I'd post some pics of a pair of custom M125's I'm working on. This is a mirrored design using cherry and aluminum (from FPE) chassis. The bias meters aren't hooked up yet - haven't decided how I want to do it.

The rest of the system - phono pre, line pre, and separate PSU's for each are of the same design. I'll post pictures of those as I finish them.

The empty cavity on the face is for an etched brass piece I haven't finished yet.

What great sound from these amps! They are dead quiet also.

Beautiful Work!

Wow is right!
What a beautiful job on those 125's. Looks like maple wood chassis sides. Very thoughtful design and the workmanship is excellent. Congratulations!

Man those look great - you should definitely think about packaging it as an upgrade - I know I would be interested.

WOW!!

Exceptional build quality! Nice upgraded chassis's. A labor of love!

Sal

I would seriously buy a pair of those from you, assuming you can come up with a way to offer bias selector for the meter, and the price were right. If this is something you'd consider, drop me note. Either as a kit or assembled.

Still thinking about replacing your VRDs David?

I would trade, even money, my VRD-ST for a pair of these custom M125's. I might even contribute some extra cash.

I stop into this forum mainly hoping to see posts like this. Well done man

Wow - thanks for the kind words. Sorry I've been away - I have to get the rest of the system finished and shipped off by Monday, so I've been heads-down on that.

I haven't considered kits or selling these. Frankly, they are far to labor intensive and costly with the custom machined pieces (around $1K), and doing the aluminum inlays by hand (x-acto knife and dremel) isn't fun. Especially when you're doing 23 of them.

The entire design is based on the preamp design, which has been evolving in my head for the past six months. Hopefully that goes well and I can get some pictures up soon.

Umm, why ya building 23 of em? selling these?

23 inlays - not 23 amps. I may build another pair for me, but that'd be it.

I hope to have better pics in the next week or so, but here's what I have now. This first shot is the entire system.




This is the line preamp. The small knob on the left is the source selector, and the one on the right is mono, mute, and stereo. There are 2mm LED's for the volume indicators - these are green, orange, or red depending on the level.




And this last is the preamp power supply - completely independent supplies for each channel. The heaters use a separate transformer located in the chassis and a symmetrical supply. This is overkill, but some aspects of the system were more show than go.

To close this out, here's what this was all about: The Knittel Lounge

Nicely done!

wOw ... just ... wOw ... well worthy of a bump in case anyone missed it the first time around.

Beautiful work. One question though ... what's this then?



I figure either a filter or step down for the time delay board?

Just a relay.  I used real Bulgin non-latching switches for power and Ti's driver board for the switch: http://www.amb.org/audio/epsilon24/.  The un-insulated connections are on the LV side.  They should be insulated but I didn't have time - I built the entire system; 6 custom chassis, the design of over 30 custom metal pieces, the art on the brass memorial badges, rebuilt the turntable, etc. in 30 days.  I had the night before to debug it before I had to pack it and next day all ~500 lbs of it to Austin TX.  The speaker cabs were done outside.

No pressure  

This pair use GZ33 rectifiers so there's no need for a time delay board.  Frankly, I don't believe in time delay circuits anyway - I've never seen proof of cathode stripping on anything less than transmitter tubes running at multi-KV voltages.  This system was built as a memorial for a co-worker, so it's more show than go.  These days I use well regulated solid state supplies.

Here's an updated link to the article I wrote on it: http://blog.moodmedia.com/2012/03/sxsw-barry-knittel-lounge/



JP

Aha ... I mistook the board for the TDR that Bob provides as an option. My bad. I went with a latching switch myself, but it has the "halo" led lighting built in. That board might be an elegant option for providing power for the LED while still isolating it from the amp. I understand they can be a bit noisy.

No pressure ... right. Quite the tribute though ... I can imagine your friend tapping his foot and smiling every time somebody fires up a goodie ...

Also went wandering thru the website and it looks like you have a fun place to work. One thing caught my eye there ... "in-store media specialist that uses a mix of music, visual and scent media" ... a veritable assault on the senses! Begs the question of what all sorts of augmentation you've added to your own home system ... I've got a lot of lights (old school incandescents, LED lightbars, and the occasional laser or two), but I draw the line on smell-o-vision.

Nah, you're not going to pick up any discernible noise from LEDs, especially in a power amp. The Chinese copies of the Bulgin switches I could get my hands on felt cheap, so I went with the real deal which necessitated the driver board due to using a momentary switch.

It was a fun place to work. I left in November of last year, shortly after it was sold.

Currently I'm a bit of a purist with my system - full range speakers, 300B amps, and no preamp aside from the phono stage. I prefer low light, no distractions, and listen with my eyes closed.

I've enjoyed every piece of gear and every step on my audio journey. I'm not sure where it'll ultimately go, but this stopover works well for me for now.

jjones3318 wrote:Just a relay.  I used real Bulgin non-latching switches for power and Ti's driver board for the switch: http://www.amb.org/audio/epsilon24/.  The un-insulated connections are on the LV side.  They should be insulated but I didn't have time - I built the entire system; 6 custom chassis, the design of over 30 custom metal pieces, the art on the brass memorial badges, rebuilt the turntable, etc. in 30 days.  I had the night before to debug it before I had to pack it and next day all ~500 lbs of it to Austin TX.  The speaker cabs were done outside.

No pressure  

This pair use GZ33 rectifiers so there's no need for a time delay board.  Frankly, I don't believe in time delay circuits anyway - I've never seen proof of cathode stripping on anything less than transmitter tubes running at multi-KV voltages.  This system was built as a memorial for a co-worker, so it's more show than go.  These days I use well regulated solid state supplies.

Here's an updated link to the article I wrote on it: http://blog.moodmedia.com/2012/03/sxsw-barry-knittel-lounge/



JP

Sorry but i do not understand the circuit, is it a momentary switch , then how do one shut off the power ? ( if it's a make/break switch i get the idea)

The driver circuit here http://www.amb.org/audio/epsilon24/ drives a relay. Each momentary contact closure toggles the relay between on and off.

It's an overly-compicated solution, but was necessary when the Bulgin switches were the only game in town if one wanted that look. Today there are plenty of alternative switches that are copies of the Bulgin look.

jjones3318 wrote:The driver circuit here http://www.amb.org/audio/epsilon24/ drives a relay.  Each momentary contact closure toggles the relay between on and off.  

It's an overly-compicated solution, but was necessary when the Bulgin switches were the only game in town if one wanted that look.  Today there are plenty of alternative switches that are copies of the Bulgin look.  

It's late here ...  But i still don't get the function. The K1 relay is part of overload indicator. Is the external relay ( across D3 ) a toggle-relay ? But then the crydon D1240 has no "toggle" it will turn on at 3-24V and stay on ...
Am i missing something ?

Ahhh, i get it, Q2 and Q3 constitutes a bistable flipflop( vippa as we call it). Nice !

I once made a simular in function but used a 9V battery for "power on", holding was supplied from the amp itself. Thus i saved the constant power and associated transformer. The 9V battery lasted for years and years ...