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A Very Compact Hybrid Amp - Page 7

post #91 of 2203
1/27/09 at 10:57pm

Red means stop, green means go

OK, before boxing the baby up thought I'd shoot a couple more pics.

I encourage those interested in the amp to read this whole thread (ha ha, hey at least 1st 2 pages) and if a DIYer & interested (not afraid of a couple parts orders & drilling a few holes) contact runeight... But here's a quick run-down of features:
  • Compact Tube Hybrid fitting on a 75mm X 120mm board (targeting Hammond 78mm X 120mm X 43mm case: http://www.hammondmfg.com/pdf/1455K1202.pdf)
  • No trimpots in frontend. Rolling 12au7 class tubes consists of turning off amp, pulling one tube & inserting another. Can be 6922 class tubes too (switch for 6.3V / 12.6V heated tubes). Other tube types may also work. SM heater regulator needs no heatsink & only gets about hand-warm.
  • Runs tubes at about twice plate voltage of some other hybrids such as the SOHA (75V, may change 2 resistors in BoM for 80V)
  • Uses discrete output buffers, rail splitter.. Driving most types of cans (very) nicely.
  • Implements AMB's e12 muting delay & offset protection (& red and green LEDs)
  • Completed build w/case & 24VAC 0.8A+ A/C adapter should come in about Edit: $150 USD plus any shipping & taxes (before any group buys or such)
  • See my posts for my initial impressions... We have another build on the way & room for more
OK, now for the LEDs. During the minute or so muting delay while waiting for tube & buffer to settle in we have the RED of bicolor LED on:

Or in the unlikely event that the e12 goes into protection mode (about 100mv offset or more). Uses direct-coupled output stage (the best kind of output capacitor - none, so this protects your cans in the event of build error or (unlikely) part failure.

After the minute or so warm up we have the GREEN of bicolor LED on.


This should satisfy your wallet, some audiophile needs and perhaps those of your SO... Maybe even getting some "Oh, that's sooo cute!"s out of the deal.
Oh, for you lady builders, maybe some "Oh, I'll take that!"s
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post #92 of 2203
1/28/09 at 4:44am
Quote:
Originally Posted by cfcubed View Post
Oh, for you lady builders, maybe some "Oh, I'll take that!"s
Er, who are these lady builders.
I thought there was only one girl on this entire forum lol...
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post #93 of 2203
1/28/09 at 6:49pm
Thread Starter 
Quote:
Originally Posted by Forte View Post
Looks very impressive, never seen such a tight layout...

What tube types can be used in this amp?
Forte, the heater supply will accomodate 12.6V and 6.3V tubes running anywhere from 150mA to 600mA. The front end servo will accomodate many types of tubes. Its design center, however, is around the 12au7 type.

These are the types that I think you can roll:

12au7 variants
ecc82
6680
6189
5963
7316
5814

6922
6dj8
8614 (12.6V 6922)

6n1p

12bh7

12at7 (may or may not work)

any other tube that has the same pinout as 12au7 and an operating point that is not terribly different.

There may be more than I have listed.

Furthermore, because the front end uses a nice servo mechanism you don't have to adjust any trimpots when you swap tubes. The only adjustment will be the slide switch for the heater supply that will select between 6.3V and 12.6V.
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post #94 of 2203
1/28/09 at 11:09pm
Is 600mA the limit for the heater circuit, or could a feller mod that to go up to 900 something?


Bravo and hats off to cfcubed for all the info and pics, thanks a bunch.
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post #95 of 2203
1/28/09 at 11:11pm
im interested in getting a board and the updated BOM as they become available.
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post #96 of 2203
1/29/09 at 12:02am
Quote:
Originally Posted by runeight View Post
These are the types that I think you can roll:
Thanks for that. Have 5 or 6 of the tubes you listed already.

Am now very interested in one of these boards to build this amp.
Is posting interest here OK or should we PM or E-mail you?
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post #97 of 2203
1/29/09 at 12:05am
Thread Starter 
Posting here is ok for now. Thanks for the interest from those of you who have said so.

Forsakenrider has his board and parts. Maybe even working on the amp now while cfcubed is working on casing.

It shouldn't be much longer. Just don't want to have anyone else spend time and $$ until we are very sure of two builds.

And, I guess I'm going to have to build one too.
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post #98 of 2203
1/29/09 at 12:12am
gotta resist ....resist ........ aaaaaaah ..dB
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post #99 of 2203
1/29/09 at 1:08am
Thread Starter 
I thought I should troll the list and PMs for those who have expressed interest. Just so that the boards are not over-promised. These are the folks who have expressed interest in the proto boards.

Ludoo
MrSlim
M0b1li3e
Nsx_23
Forte
Keyid
Alfiax

Please let me know if you are on the list but should not be or vice versa.

I have 10 boards. There won't be any kits for this distribution, but I'll supply a BoM and I will try to build out this portion of the Cavalli Audio website so you won't have to constantly look through this thread.
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post #100 of 2203
1/29/09 at 1:47am

Green means go... Build one yourself:)

Quote:
Originally Posted by dBel84 View Post
gotta resist ....resist ........ aaaaaaah ..dB
Now you know that won't be possible...



Got all casework done & boxed it up tonight in about 4 hours... It really seemed a bit too easy. I have done a couple SOHAs before as a warm up PCB itself took me something like 6-8 hrs build time (slow & careful) not including time to use the right/specified BC560s

Tools included sharpie, rule, patience, large Greenlee step drill bit, drill index, small file and $60 HF drill press (Nemo says he uses hand drill.. Must be steady hands)

She's been working & sounding fine for over an hour now. Case gets a bit warm as I've case bottom mounted the only part needing a heatsink - the 24V LV reg. Can see myself drilling a nice ring of holes around that chrome tube ring and maybe some more on the sides...

Changed from EH ECC82 to Raytheon CK5814A last night, tonight RCA 5814a then back to EH ECC82 which I'm liking. Yes, about 8 secs to change tubes makes that fun

When it gets warmer outside I'll use that gray vinyl dye on the end plates to make it even more sexy

Here's a shot just before boxup... Gotta say, runeight did a great job on the PCB layout, esp. for a 1st proto run:


Here it is with cans & ipod for size perspective...


Here's the back w/fuse, heater 6V/12V slide switch & A/C in... Went w/o power switch cause its easy to use the rear plug..


Guys - you are going to like this thing.
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post #101 of 2203
1/29/09 at 2:05am
Quote:
Originally Posted by dBel84 View Post
gotta resist ....resist ........ aaaaaaah ..dB
Too....many....projects!!! But that is soooo sweet looking...
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post #102 of 2203
1/29/09 at 4:24am
no kidding

congrats all , this has truly turned out to be a very cool project ..dB
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post #103 of 2203
1/29/09 at 5:51am
cfcubed, that looks awesome. For sure I am building one of these. Will have to see if there is any interest in an Aussie group buy once it is officially available.
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post #104 of 2203
1/29/09 at 6:27am
Quote:
Originally Posted by cfcubed View Post

Here's a shot just before boxup... Gotta say, runeight did a great job on the PCB layout, esp. for a 1st proto run:

Fantastic job cramming everything into such a small enclosure. Initial impressions sound VERY promising.

All we need now is to hear from the second prototyper.................
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post #105 of 2203
1/29/09 at 7:53am
That looks fantastic! I hope its not too difficult for somebody stepping up from a CMOY....
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