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A Very Compact Hybrid Amp - Page 9

post #121 of 2213
This is where I'm at. Im lovin' this thing!!

post #122 of 2213
Wow, very nice.

Having a tube and other hot stuff in there has me concerned though... Is there enough room on the back panel for a small vent fan?
post #123 of 2213
I haven't seen any temp readings, but I'd assume they aren't sky high - The tube would get warm to the touch, but I imagine the power supply and buffer doesn't dissipate too much heat. Any measurements from the proto team?

My SOHAII heats up the volume knob with a perforated top!


Quote:
Originally Posted by Moontan13 View Post
Wow, very nice.

Having a tube and other hot stuff in there has me concerned though... Is there enough room on the back panel for a small vent fan?
post #124 of 2213
How many more proto-typers are working on these?

Was 130 the price with the case for this BOM? How many different places did the parts need to come from? This project looks exactly like what I wanted when I first looked into DIY.
post #125 of 2213
Quote:
Originally Posted by Moontan13 View Post
Having a tube and other hot stuff in there has me concerned though... Is there enough room on the back panel for a small vent fan?
Gotta run but wanted to post quick info to this query... The only "hot" items of any significance in this project are the tube & LV 24V regulator.
If you look at pics of my build, the tube pokes out through a (slightly) oversize hole in the top. And there are holes on the case sides AND a bunch on the case back. Since I case-mounted the 24V reg, my whole case was getting warm (not by any means hot), so I'm drilling about a dozen 3/16" holes in the top

There is absolutely no reason for active cooling in this design. Just a somewhat perforated top & a way for cooler air to get in (side, back holes).

Our TO92 output buffer devices get "quite warm" but are not pushed near their limits, even though this amp is designed to remain in Class A while driving most headphones at sane listening levels.

Edit: Waitrob - I have a old-style outside thermometer (thermistor on a wire) that I'll use to measure within case temps after I drill those holes in the top. I'll post back with readings but expect them to be quite reasonable (case innards likely to be "warm").
post #126 of 2213
Second Impressions:

After a few more hours (8 or so..) I have settled on an Amperex Bugle Boy 6DJ8. I will compare it to my SOHA even though I dont really think its fair. With the small size, heater switch and "auto-bias" (If I can call it that???), the SOHA is no match. The SOHA is an amp for opamps, as I feel rolling opamps through it was more fun the rolling tubes, but with the jisbos that changed and so did its ability to drive high Z phones. Jisbos are made to handle low Z phones, the CTH is capable of whatever you throw at it. This amp gives me a new meaning to the word definition. Every note is clear and full. This amp drives bass in my AKG's I have never heard before. Highs shine like crystals and the mids smooth out the in between. I seriously have trouble deciding what to listen to. I hear something new in every song I turn to, from heavy metal to classical it all "fits".
I can not imagine ever wanting another head amp. This fits on my desk, I can swap tubes in a second, plug in any phones and just "be" with the music.
post #127 of 2213
Quote:
Originally Posted by cfcubed View Post

Edit: Waitrob - I have a old-style outside thermometer (thermistor on a wire) that I'll use to measure within case temps after I drill those holes in the top. I'll post back with readings but expect them to be quite reasonable (case innards likely to be "warm").
Way more advanced than the oven thermometer I pressed up 'gainst the heat sinks on the SOHAII proto! I'm curious about temps...
post #128 of 2213
Quote:
Originally Posted by forsakenrider View Post
Second Impressions:
<snip>This amp gives me a new meaning to the word definition. Every note is clear and full. This amp drives bass in my AKG's I have never heard before. Highs shine like crystals and the mids smooth out the in between. I seriously have trouble deciding what to listen to. I hear something new in every song I turn to, from heavy metal to classical it all "fits".
I can not imagine ever wanting another head amp. This fits on my desk, I can swap tubes in a second, plug in any phones and just "be" with the music.
Wanted to note that my impressions of the amp are very much like the above, but thought/think it carries more weight coming from someone else

I find it has frequency & dynamic range like no other tube amp I've heard (headphone or otherwise)... Although I've not auditioned other "high-end" headamps, like some of runeight's other designs, think its fair to say this thing will give DIY headamps costing 2X+ a run for your money.

If you've a 0.8A+ 24VAC adapter & 9-pin mini tube socket around you should be able to have a complete build (incl $15 USD case) for roughly $115 USD plus any shipping & taxes.

We've BoM (req orders from 2 vendors), build tips, zoomable PCB & silkscreen images, case hole drill guide and even closeup photos to help...
Enough said I think - It's back to the music for me
post #129 of 2213
Quote:
Originally Posted by forsakenrider View Post
I can swap tubes in a second, plug in any phones and just "be" with the music.

I love that description

Have you finished casing it up and how hot does the case get with the heatsink?

Also have you listened to it with a 12AU7 tube?


cfcubed - What tubes have you tried so far and is there much difference between them?
post #130 of 2213
All I have to do Is drill the hole for the tube and heater switch. Maybe a couple in the side but im trying to avoid as much swiss cheesing as possible. otherwise its all boxed up with no top.

I have rolled, JJ 12au7 gold pins, RCA 5814a black plates, Conn branded 12au7a Clear top, Bugle Boy 6dj8 and two other sylvania 12au7 varients (crap, what are they?). One of the sylvanias that I didnt like in my soha is much nicer in this amp. The BB 6dj8 is my favourite right now and ive been told its an amazing tube by many. Ive ordered some more variants already to play with.

rolllly rollllly rollllllllly rolllllllllly
post #131 of 2213
Thread Starter 
Gents, I believe it's time to send out the rest of the boards. Looking through the thread again, here are the folks who have indicated some interest in a board. Please PM me with contact information. There are 10 boards available.

Ludoo
MrSlim
M0b1li3e
Nsx_23
Forte
Keyid
Alfiax

Thanks.
Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #132 of 2213
Runeight.. pm sent..
post #133 of 2213
Can't believe wiatrob hasn't asked for one yet... He can always build it for me...
post #134 of 2213
Quote:
Originally Posted by HeadphoneAddict View Post
Can't believe wiatrob hasn't asked for one yet... He can always build it for me...
You haven't seen my workbench - I'm having to build a second right now! Is that a request?
post #135 of 2213
Should some of the others not have time or funds.....my bench can be cleared for this.
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