[Eric1285]

Quote:

Originally Posted by tomb [size=medium]PIMETA Pairs[/size] A PIMETA pair designed and built with perfboarded, LM317 (TO-92) Trickle Chargers. Trickle charger is designed so that wall-power is always charging at a very low rate, with plenty of reserve to power the amp. So with batteries charged, plugged or unplugged makes no difference. Walwart is a Jameco #174861 24VDC@500ma linear, regulated wallwart through a standard 2.1mm isolated (plastic) socket in the rear. The trickle charger and battery/power leads are nestled between the batteries. Charged battery life is approx. 4-6 hours without the walwart. http://www.paintedpostcards.com/misc1/PIMETApairs1.jpg[/IG] [IMG]http://www.paintedpostcards.com/misc1/PIMETApairs3.jpg[/MG] 470uF Nichicon UPW (10x16mm shorty's) Double stacked BUF634, single on Gnd, Class A bias trannies AD8066/AD8065 in one, AD8620/AD8610 in the other Batteries are 8.4V, 250mah from the Shoreline Market on Ebay. Hammond 1455J1201 cases The design/build thread was most recently documented here: [url=http://www6.head-fi.org/forums/showthread.php?t=187592]Trickle Chargers[/url] P.S. Many thanks to Tangent and __redruM![/i] [/td] [/tr] [/table] Hey, what sorts of knobs are those? I'm getting the same enclosure and they look fantastic!

 

[xikteny]

Quote:

Originally Posted by Eric1285 Hey, what sorts of knobs are those? I'm getting the same enclosure and they look fantastic!

They look like these, from Radio Shack.

 

[tomb]

Yep - RatShack specials. I always thought they looked pretty chintzy in the store, but it seems to add the right touch with these. Thanks.

 

[saturnine]

Quote:

Originally Posted by jcx The heat sink is a Zalman Golden Orb II

That's actually a Thermaltake Golden Orb, a slight ripoff of the Zalman 7700 series

Extremely nice work though, I'm very curious as to how it would sound..

 

[flecom]

Quote:

Originally Posted by Towert7 Wow, it's not every day you see something with BNC connectors. Nice work NeilR.

hehe, real men use 7/16 DIN connectors

 

[The Monkey]

Quote:

Originally Posted by NeilR Tangent recently made LNMP boards available. I have wanted one of these tools for some time now and found it to be a fun and interesting build. Pretty much stock except I added a trim pot to the 3rd gain stage to independently calibrate the 100 and 1000x gain settings.

Neat. Thanks for including the link to the gallery. Very helpful. What kind of enclosure is that, by the way?

 

[NeilR]

Quote:

Originally Posted by flecom hehe, real men use 7/16 DIN connectors

No... real SMART men multi-task their scope probes and interconnects

 

[Towert7]

Quote:

Originally Posted by NeilR No... real SMART men multi-task their scope probes and interconnects

Tell me you don't have it connected to some medical/scientific grade oscilloscope.

^_^

 

[NeilR]

Quote:

Originally Posted by The Monkey Neat. Thanks for including the link to the gallery. Very helpful. What kind of enclosure is that, by the way?

Monkey, that is the 546-1455L1201, which is a very nice size case. I'd like to do an audio amp type project in that case some time. It was even worth a little pain and sufffering to lay out the panels and get all the tall parts packed in. I ended up just covering the entire inside top with teflon sheet rather than work out what might touch where. OneTO-220 chip is leaning backwards, for a reason

. The other I bolted to the board so that I could heat sink it without cutting off part of the top and bottom of the sink.

One mod I did do to the circuit was to use a thermistor for temp controlled backup termination. That worked out pretty well, although it is a close race as to what terminates fast charge - NDV or the thermistor because I used a very conservative value for the temp cutoff.

 

[NeilR]

Quote:

Originally Posted by Towert7 Tell me you don't have it connected to some medical/scientific grade oscilloscope. ^_^

No, just an HP 2235 and Fluke 97, but I've spent enough money and time buying and making probes and ICs

 

[jcx]

Quote:

Originally Posted by saturnine That's actually a Thermaltake Golden Orb, a slight ripoff of the Zalman 7700 series Extremely nice work though, I'm very curious as to how it would sound..

re:
http://www6.head-fi.org/forums/showp...postcount=1365

You’re right - I don’t know where I got crossed up – possibly it was hanging among the Zalman’s in the store display

I think you can see the edges of the “T” in the ThermalTake Tt logo on the steel heatsink mounting bracket in the photo below

[side view shows thermal path, 6 TPA6120 op amps with their Power Pad belly patches pressed against the Copper slug of the Golden Orb heatsink]

As for amplifier ”sound” I’m in a curious position since I really don’t believe 90+% of what I read here on op amp sound/rolling and audible differences between amplifiers can possibly be true of any decently linear, low impedance amp run within its Voltage and Current limits

One possibility is that many times the amps here are clipping and there may be differences in recovery behavior that affects the sound

Which is one motivation for building an op amp based amplifier approaching the Gilmore “Dyna” levels of output capability

Otherwise we have to conclude that most people posting here are in ignorance/denial of well established psycoacoustic testing principles such as Fletcher-Munson curves and level matching requirements, our really limited audio memory and rapid perceptual accommodation as well as the unconscious biases from our inescapable mental processing that fits sensory data to our mental perceptual framework that make blind testing an absolute requirement

 

[divie23]

Standard PPAv2 with STEPS, Class A OPA627s at 2mA.

I put a lot of work into the casing, The front panel is from FPE and was well worth the effort. Just listening to the amp right now.

 

[phergus_25]

HP stand... pardon the bad pics, i plan to get some better ones.

 

[rreynol]

Quote:

Originally Posted by divie23

It's a headfi requirement (at least it should be) that if you get a FPE panel done, that you have to get a nice clean shot of it. It's hard to even make out what you had engraved.

Very nice work!

 

[mb3k]

Quote:

Originally Posted by phergus_25 HP stand... pardon the bad pics, i plan to get some better ones.

That's a slick looking stand! I can't tell by the photo, but how tall is the stand?
I'm thinking of making one for myself too