Post pics of your builds.... - Page 274

Transformers to balance unbalanced inputs.

thanks for the kind words.

I will write-up some kind of tutorial; its been long overdue. I'd like to share the 'secrets' I've picked up over the years on product photography.

the summary, though:

- tripod and self timer to avoid shake

- preview the image to verify the depth-of-field (stop down view or live-view)

- use the largest number f-stop you can but try not to go past '3/4' of your total range (larger f-stop number is 'more front/back in focus' but also you lose sharpness due to 'diffraction' with TOO much stop-down).

- try to get 5-10 seconds of exposure (long, not short). this will happen when you use a large f-stop and you may still need to use a ND (neutral density) filter to slow things down even more. or maybe a polarizer.

- when the camera goes off on self-timer, you have that 5-10 secs to do my 'flying lights' trick, as I call it. take a flashlight and wave it around, keeping it in motion, trying to hit the subject with light from 'many angles'. this is a poor man's 'soft box' but do this on a SOLID floor as any bounce on the floor will cause the tripod to shake and lose sharpness.

that's the main idea on the shoot. there is about half (more) in technique in PP (post processing). I'll cover that in my more formal write-up (short hint: the 'shadow/highlight' tool is worth its weight in gold in 'fixing' a lot of unbalanced lighting. no, it does not convert from single end to balanced - lol). another hint is to always work on the image at full size (1:1 pixels) and ONLY resize down at the FINAL step before you are about to 'print' or save-for-web. and right after you resize, THAT is when you do your single sharpening pass (unsharp mask).

hth a little. I'll write a bit more later on the whole process with screen shots of photoshop, etc.

oh darn...

well, I still have something to work on for this, then. too bad, since the offboard connectors were so nice and happy there

btw, I have low voltage going into the pimeta and this board (not even 20v, more like 17v). should I change the zener out - or do I have to do more to make this circuit run at that lower voltage?

doh!

sigh. yes, I missed this. thanks for both of you catching it!

I'll 'edit' the circuit board underneath. the silkscreening is something I want the user to 'trust' when debugging this years from now

Just swapping the zener isn't enough. The relay is a 12VDC unit, and we have the power supply split in half to run it (24V / 2 = 12V). You can't run this circuit at anything less than 24V unless you change to a lower voltage relay in addition to changing the zener.

I didn't catch this detail.

perhaps I'll re-do my PS (yet again) and try for something closer to 24v. I am betting the relay will latch in at 10v (maybe?) and so if I'm at least 20v I'm hopeful it will work. but I will try for a 'full' 24 if I can.

also, since my source stage is a pimeta with its own (single) rail splitter, would it actually be better to tap into this as my zero-point instead of splitting it 'yet again' in the epsilon board? I wonder if, in this case and config, using the definitive/actual 0v point from the pimeta would be simpler and actually more accurate? the 2 splitters could actually be 'arguing' about who has a better idea of (x/2), so to speak

The ε12 was designed to be adaptable to many classes of amps, from those with real dual rails, split-rail virtual-ground, single-rail amps, passive or active output ground, unbalanced and balanced, etc., thus it cannot rely on the topology of any one of them. Hence the design to make its own virtual ground that's adjustable.

Btw, since this is a "Post pics" thread, we've gone way off-topic. Please continue any similar discussion in the official ε12 thread at headwize.

MiniMAX X2

I finished my two MiniMAXes over the New Year's holiday.

Thank you Colin and Tom for making these wonderful amps available to us DIYers.

an external power supply was needed, so I hacked one together from mostly spare parts:



the pc board is tangentsoft TREAD. the transformer was from the hk/ebay noodle-dac (as it seems to be called). the ugly mess on the right is a lead-supported (lol) lm7805 for my utility 5v supply (IR receiver board, local DAC, even motorized pots). the TREAD gives me a cleaner 20-24v for just the amp section (oh, and the e12 too, I guess) the rear has an IEC power connector and line filter combo (might actually help and can't hurt). the case was a spare switching supply that I removed and discarded.

nice. you even matched colors on details.

I have my minimax box and I'm planning on building one, soon, too

Wow !
I was a bit sceptical about LEDs under the tubes, but the blue LED and the black case look HOT !!!!

Can't wait for my gear to arrive !!!!

I'm looking forward to your excellent photos of your fine craftsmanship. I'm sure you will enjoy the Mini.

As a stuck-up tube purist, I didn't use tube LED's on my earlier MAX Hybrids. However, for the MiniMAX I decided it was time to move into the 21st century and gave it a try. I'm glad I did!

They look awesome

@ WilCox,

Nice work and coupled w/some nice headphones I see. Makes me wish I would've got in on the build.

Very professional,

Matt

Ooh, I want that millet. Badly.