[dBel84]

Thought I would post some images of my latest successful project. This is a tube based unity gain buffer which uses a 6922 tube. As Runeight described it" a unity gain low Zi high Zo switchbox capable of driving long cable runs" It has been a long time in the making as I kept allowing myself to be distracted. The disadvantage of it taking such a long time is that the final design evolved but I had already collected many of the parts and thus continued on the earlier version of the design. The design is one of Runeight's over at headwize http://headwize.com/ubb/showpost.php...=55702&fpage=1 . I have had it running for 2 days and it works like a gem. Not quite finished but good enough to get a taste as to what it sounds like..dB

 

[amb]

Quote:

Originally Posted by dBel84 /img/forum/go_quote.gif a unity gain low Zi high Zo switchbox capable of driving long cable runs

I think you got it backwards... it's high Zi low Zo. Otherwise it would be a bad load to the volume pot and can't drive a long cable...

 

[dBel84]

indeed

, thanks AMB..dB

should have been:
" Occasionally we need a buffer between source and amplifier that has unity gain with a volume control and/or a source selector switch. People often use passive attenuators for this, but passive attenuators have problems because they generally have a high output impedance.

What is needed in this situation is an "active attenuator" that has high Zi, low Zo, and unity gain. We want this buffer to have as little THD as possible and it has to be able to drive cables of reasonable length."

 

[gates_2]

A new pimeta- just finished up last night

Panasonic fm rail caps
OPA 637/627 combo
2x stacked smd BUF 634's
All vishay RN55
Trickle charger(LM317) based on Tomb's thread
2x 8.4V rechargable batts


How does it sound? Awesome. Fitting in a pocket=even better.
I think I've found my new favorite portable amp.

As for battery life, haven't done much testing yet, but it should be enough to last through the day with moderate use.

 

[tomb]

Quote:

Originally Posted by gates_2 /img/forum/go_quote.gif A new pimeta- just finished up last night Panasonic fm rail caps OPA 637/627 combo 2x stacked smd BUF 634's All vishay RN55 Trickle charger(LM317) based on Tomb's thread 2x 8.4V rechargable batts How does it sound? Awesome. Fitting in a pocket=even better. I think I've found my new favorite portable amp. As for battery life, haven't done much testing yet, but it should be enough to last through the day with moderate use.

Hey! That looks familiar. Great job!

 

[tomb]

My recent work - Cetoole's new take on the familiar Millett Hybrid. The Millett Hybrid Max:

 

[rsaavedra]

Just finished improving the heatsink extension for my Dynahi.

Here's the one I had built before:

In that first version I used a folded-over copper sheet to connect the right front main heatsink to the extension.

With that setup the two front heatsinks would get really really hot, while the extension would get just warm to the touch. A better heat-communicating path was needed, and that's why now I did this:

Believe it or not, those copper "belts" you see now connecting the two main heatsinks with the extension are (were) gas pipes. Got 3/4" diameter copper pipes from the hardware store (couldn't find larger), hammered the pipes down till they were flattened completely, and used them as shown.

This new approach not only provides a better heat conducting path, it also connects both front heatsinks to the extension, so the heat will be spread more uniformly overall.

 

[seroxatmad]

Hi all

@Tomb

Can you direct me to a link/website where i can get info on your Millet Max and Pimita?

John

 

[pheonix991]

Quote:

Originally Posted by seroxatmad /img/forum/go_quote.gif Hi all @Tomb Can you direct me to a link/website where i can get info on your Millet Max and Pimita? John

http://www.google.com/firefox
http://www.head-fi.org/forums/search.php

 

[tomb]

Quote:

Originally Posted by seroxatmad /img/forum/go_quote.gif Hi all @Tomb Can you direct me to a link/website where i can get info on your Millet Max and Pimita? John

Millet Hybrid Max:
http://www.diyforums.org/phpBB2/viewtopic.php?t=292

The PIMETA is actually described in a thread I posted on Trickle Chargers

 

[khbaur330162]

rsaavedra: That's a really cool mod. My Dynahi runs pretty dang hot after about an hour of listening. I've got a big fan on it currently. Maybe some modding is in order.

Thanks for the ideas!

 

[RedBeardatXM]

Quote:

Originally Posted by drewd /img/forum/go_quote.gif Work sounds so good!

I love the enclosure, what was that extrusion for originally?

Dan

 

[amb]

Quote:

Originally Posted by RedBeardatXM /img/forum/go_quote.gif I love the enclosure, what was that extrusion for originally? Dan

If you're talking about this one, I believe it's an old HeadRoom amp case:

 

[Tsappis]

I made a simple switch box yesterday (3 in 1 out).
Hammond case, Alps switch, some cheap-ish connectors and teflon insulated silver plaited stranded copper wire.
A classic combination, as one might say

 

[digi01]

some work of last year.