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A Very Compact Hybrid Amp - Page 11

post #151 of 2203
2/5/09 at 1:07am
I couldn't resist. My hat's in the ring too.

20mA before falling out of class A? What are the clipping points into low-Z?
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post #152 of 2203
2/5/09 at 12:47pm
Quote:
Originally Posted by holland View Post
I couldn't resist. My hat's in the ring too.
20mA before falling out of class A? What are the clipping points into low-Z?
Great, glad to have you on board... We must be getting close to 10 prototypers by now...

> 20mA before falling out of class A? What are the clipping points into low-Z?

Runeight will have to answer this when he takes a break from other things Seems to me we aren't driving the BC3X7s too hard using the current BoM comps (don't need the TO92 heatsinks that may appear on it). Think he's slowly putting together something on his site about this amp...

Since you guys should be getting parts & PCBs soon, here's my personal build tips:
  • Alps RK097 series pots have 6mm shafts. I used heatshrink on it to use 1/4" shaft knob Mouser 450-6016 (can use straw)
  • Proto PCB & BoM may req tilting in C5P & C10P slightly to fit board in case.
  • about a dozen side & top holes may suffice.. I staggered side holes because it's hard for hacks like me to make straight even spaced holes
  • BoM heater slide sw was smallest I could find (other than the RadioShack 275-406 submini I used). See pic below - can also see my bottom mounted LV reg (again don't need to do that)
  • Since tube amps like to be on for a while I didn't use a pwr switch... Used fuse instead to protect my wallwart.
  • If a part is out or has silly min qty consider finding alternate of same type, value, rating & size.
  • Be careful if probing around the PCB when powered on - its quite tight in there!

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post #153 of 2203
2/5/09 at 2:51pm
Thread Starter 
Here are a few additions to cfcubed's build tips.
  • I'll be building out a section of the CA website soon so you'll have a reference for information
  • The C5P and C10P in the BoM are smaller diameter than the originals, but they have smaller lead spacing. The should fit without tilting if mounted on the inside pad towards the center of the board
  • DON'T, DO NOT substitute transistors unless you really know what you're doing. The BoM calls for specific gain classes ("25" and "C"). Don't mix gain classes. If you do, the buffers are likely not to be able to zero properly.

Boards are starting to go out to the next group of prototypers.
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post #154 of 2203
2/5/09 at 4:56pm
Well, I'm pretty psyched. I just put my orders for components in, so given a small amount of luck with the postal system everything should be in place to start my prototype some time next week. I have a small range of slightly more 'unusual' dual triodes lying around which might work well in this circuit-- if any seem to work well I'll report in...
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post #155 of 2203
2/5/09 at 11:07pm
Quote:
Originally Posted by gore.rubicon View Post
if the price is right, sign me up, im a starving student, and the tubes used in this amp (to me) seem a bit more available compared to the 19j6s
Maybe you meant to put a smiley at the end of the understatement?

An ebay - Vintage Elect/Tubes search for the list of tubes that should work in this amp:
(12au7, ecc82, 6680, 6189, 5963, 7316, 5814, 6922, 6dj8, 8614, 6n1p, 12bh7)
yields about 600 hits (600X # of 19j6 listings) ATM.

And although you only need one tube for this amp, you'll want to try others... Although a dozen or so brands/varieties may rise to the top of heap, they all tend to have their own distinct qualities. Lots of people will probably have their own favorites in this amp. I liked my EH 12AU7 that I dismissed in my SOHAs. And reading forsakenrider's review I'll be picking up a BB 6dj8 for sure

Alfiax - Well, I'm pretty psyched.
Cool... Let us know how it goes.
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post #156 of 2203
2/5/09 at 11:42pm
did I miss the bom post? If not, I'll start piecing parts off the schematic.
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post #157 of 2203
2/6/09 at 12:09am
Quote:
Originally Posted by holland View Post
did I miss the bom post? If not, I'll start piecing parts off the schematic.
If runeight has a PCB for you then drop him a PM or something with your email addr & he'll send the BoM.
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post #158 of 2203
2/6/09 at 1:00am
Are we assuming the wallwart will be scrounged? I did some snooping in my giant stash of power bricks - 24V 1+ amps are a bit hard to come by (I found none.)

I sourced one with my Mouser order for about $10.00 - should we just include this in the Bom?
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post #159 of 2203
2/6/09 at 1:19am
Thread Starter 
I guess we were assuming that they were so ubiquitous that everyone would have easy access to one.

Mouser does have one as you discovered and we can include it in the BoM. Probably a good idea.
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post #160 of 2203
2/6/09 at 1:28am
I couldnt find one at mouser almost ordered from Jameco, part number please
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post #161 of 2203
2/6/09 at 1:37am
507-XR-2440LED


Should work. It looks like it's the only one (that's not 'medical grade' - that's optional for the power cord crew!
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post #162 of 2203
2/6/09 at 1:37am
Thread Starter 
I see that I am wrong. I could swear that I found one when we were doing the prototyping, but I don't see one now.
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post #163 of 2203
2/6/09 at 1:38am
CRossed posts - look again, it hides...
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post #164 of 2203
2/6/09 at 1:50am
Thread Starter 
Wow, that's not the one that I thought I found. It's current rating is a bit high, but it should work. Does it have a 2.5mm plug?
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post #165 of 2203
2/6/09 at 2:14am
There is also 20va 24vac version .8amps
507-XT2420
a couple dollars cheaper.

But theres no end plugs.
http://www.mouser.com/catalog/637/1948.pdf
there is two tabs for the power wire. Im thinking of permanently attaching the adapter to the amp.
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