Doug Self Preamp from Linear Audio #5

Hello Jeff, It is nice to see you here.

In this case i was referring to the phono blocks that I provide in the PCB kits. The LEFT/ RIGHT balance control assumes 'RED is RIGHT' and 'WHITE is the LEFT' channel.

Thank you, Carl. That is crystal clear. And leaves me puzzled why several chassis layouts, employing the I/O board and your phono blocks, are labeled incorrectly. Minor detail and just my OCD, does not affect function!

BK
 
Some pics below of the "finished" product. I went with a 16x12x2" alodine par-metal enclosure to match with some other projects on my rack. Neglected to account for the larger shaft nut on the Lorlin and stole some larger black knobs for now. The front/rear panels are temporary until I get something from FPE with labeling, but this allowed me to exactly confirm the layout. Grounded xlr pin1 to the chassis with short wires. Needed a tantalum cap on the I/O board to get 12V. Added a rotary mute switch (the inner black knob) - heck, had to do something with the minimum order qty 5 Lorlin switches!

BK
 

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Par-Metal . AMB’s website has details about how to order them to get that look. Essentially, you ask for front panels front and rear, but without the panels themselves. Then order 4mm panels from Front Panel Express.

Yes, that's it, although what I show is with the default par-metal front/back panel that I drilled myself to verify my pattern. 16x12x2 is not a standard size, but it shipped within a day or so and is very reasonably priced. Just email them for a quote. My other project with this enclosure is the AMB gamma-3 DAC.

BK
 
Setup in my system today. All functions appear to be working correctly and it sounds good fed from the gamma-3 DAC via xlr.

My perception is that the "HI FREQ" far right pot functions in the opposite direction of the labeling. I read another report of this in the thread.

No glamour shots here - just a tower of DIY gear (excluding the 14 projects stacked in the garage, lol).

BK
 

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Setup in my system today. All functions appear to be working correctly and it sounds good fed from the gamma-3 DAC via xlr.

My perception is that the "HI FREQ" far right pot functions in the opposite direction of the labeling. I read another report of this in the thread.

No glamour shots here - just a tower of DIY gear (excluding the 14 projects stacked in the garage, lol).

BK


Would you introduce these guys to us?
 
Would you introduce these guys to us?

DIY gear? On top is a Whammy setup as a preamp, B1 Korg preamp, AMB Gamma-3 DAC and PS, and of course the newest addition the Self/Huff preamp on top of the Oppo. The big DIY amps mostly out of vew are FW M2 and FW VFET. Speakers are SEAS A26. For casual listening I stream a lot of USB digital from the dedicated MacBook Air out to the Gamma-3. Turntable is a Technics 1210GR with AT 740ML MM cartridge and setup on a very solid 15" Rythmik subwoofer (disconnected a long time ago, strictly 2ch now, makes a great table @ 100+ pounds!).

BK
 
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One basic question to Carl specifically (because he designed the I/O board), and others:

Is it necessary for the designer to decide that inputs 1 and 2 will be balanced, 3 and 4 will be unbalanced, at the time of design? Can't all analog inputs have both balanced and unbalanced sockets, for an amp which has balanced input circuitry? (I understand that this will mean that the relay count will increase, because you'll have to make provisions for double the number of signal lines even for those inputs which the user may have never decided to use balanced.)

But from the point of view of audio quality and just PCB design, is there a problem if we do this? I am seeing a lot of good commercial products which seem to provide both types of connectors on the same inputs, and I'm pretty sure there are no sensors or switches internally which, say, re-route any signal depending on the plug you connect.
 
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