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A Very Compact Hybrid Amp - Page 8

post #106 of 2213
Thanks for the kudos everyone...

Runeight & I worked long & hard to make this headamp a winner... Mostly runeight's grey matter & my hands Been a great dev experience... Runeight patiently explaining how things work, why certain approaches are better, etc. but always fully considering others input. The way it should be.
For example, when I thought opamp buffer & trimpots were o.k. he patiently steered the project away from them. Again, always trying avoiding compromise while still meeting project goals (single PCB, target case, through-hole construction). OK, enough don't want to embarrass him too much

So loving the amp this AM @ work... I'll be re-discovering my 12AU7 collection in this baby & maybe checking out some 6.3Vers too. Now some answers:

Ventilation - WRT my bottom-mounting the 24V LV reg... The good - it uses case as heatsink, the bad - its uses case as heatsink (unfair to other components in there). So some ventilation holes in the top (or use that nice perforated alum) are headed my way.

> Is 600mA the limit for the heater circuit -

Yes, it leaves us the desired 25% current headroom (LM2595 = 1A continuous part, we've used 0.8A parts in BoM). And National's tools say the LM2595 needs no heatsink at these operating points.

> I hope its not too difficult for somebody stepping up from a CMOY....

For 1st / 10 proto PCBs would like a bit more experienced builders I should think... But if you've other experience & are somewhat meticulous no problem.
Imagine going from a 4x4 - 16 piece jigsaw puzzle (CMOY) to a 13x13 - 169 piece one in a space that is about 2X-3X a CMOY. The pieces are numbered tho

> I've used "cute" in reference to this amp....

True, but it is kinda like saying Tokyo is a nice, quaint town. In fact my son said the completed PCB reminded him of a miniature NYC. Lots of great things happening on this board... Perhaps too many to call it "cute".
post #107 of 2213
Uh oh, Im hearing lots of reference to that "second prototyper". The plan is to have it done by saturday. here we are so far, All the resistors have been mounted. A large print out of the silkscreen image is an absolute MUST.

post #108 of 2213
This amp definitely seems worthwhile building, hopefully someone who has been around this forum long enough will step up to make a aussie groupbuy when the final release boards are out.

Meanwhile looking at that pic, it seems that a few resistors are mounted perpendicular to the board while the rest are flat against it. Is there any chance in making the board even smaller by converting all the horizontal resistors to be perpendicular?

I know such a drastic change would be a pita for you designers, but for those people who plan to make their own custom enclosures, the smaller it gets without compromising the ease of build of through-hole components, would definitely make this amp shine more then it already has.

Also out of curiosity why is uhh.. D3E crooked :P
post #109 of 2213
lots more progress this morning, only caps remain!!! Sheesh I might even get it finished tonight!..... we'll see.

post #110 of 2213
Thread Starter 
Quote:
Originally Posted by Bismar View Post
This amp definitely seems worthwhile building, hopefully someone who has been around this forum long enough will step up to make a aussie groupbuy when the final release boards are out.

Meanwhile looking at that pic, it seems that a few resistors are mounted perpendicular to the board while the rest are flat against it. Is there any chance in making the board even smaller by converting all the horizontal resistors to be perpendicular?

I know such a drastic change would be a pita for you designers, but for those people who plan to make their own custom enclosures, the smaller it gets without compromising the ease of build of through-hole components, would definitely make this amp shine more then it already has.

Also out of curiosity why is uhh.. D3E crooked :P
Bismar, this could be done. The main reason not to is that stuffing the board is already complex and the silkscreen part labels can easily be mixed up because everything is so close together.

Tombstoning all of the resistors would pack everything even closer together and it may be impossible to put proper part labels next to each part legibly.

As for D3E I refer you to the PDF of the board provided on the very first post of this thread.
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 #111 of 2213
This project looks good, congrats on the progress!
post #112 of 2213
Quote:
Uh oh, Im hearing lots of reference to that "second prototyper".
Sorry, No pressure. Great to see your build progressing.
post #113 of 2213
Just wondering, would it be possible to bottom mount the taller components to lift the board up in the case to expose more of the tube?

And how large a heatsink would be needed if you didn't want to use the case to heatsink the 24v reg?
post #114 of 2213
Thread Starter 
Forte, I don't think bottom mounting can work. The two large electrolytics will prevent this because they are as tall as the inside of the case. If they are bottom mounted then the tube socket itself will have to protrude through the top.

A small wrap-around finned heatsink that can attach to the regulator should work. The board was designed with room for this heatsink to stick its fins towards the inside of the box. It may be necessary, however, to provide ventilation above the heatsink to let the heat out.

I think that forsakenrider is building the amp in this fashion to test this.
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 #115 of 2213
I just bought a bunch of 12AU7s for this project. I'm not sure if I should just ask for a board now or wait until a kit comes out... depends on how much time and money I have. I definitely do intend to build one at some point in time, though, so I'll be continuing to view this thread with interest.
post #116 of 2213
Quote:
Originally Posted by runeight View Post
I think that forsakenrider is building the amp in this fashion to test this.
ACTUALLY, this is the one part Im undecided about. The board is completely populated now EXCEPT that 24v reg. I will dig through my box and see what kind of heat sinks I can find and get back to that idea.

Im HOPING my teflon silver wire will be in my mail box tonight so I can complete this... If its not there I will use something else and swap it out later.
post #117 of 2213
So intriguing ... That's a beauty.
Seeing One proto finished and read about it, I'm salivating :P must resisted indeed.
Lucky me, my job is quite busy right now. If it isn't so, I might already begin to build one myself.

cfcubed, that's a very neat AMP. I like the Chrome ring. Where did you get it and how much?
I like to have a couple of that ring as well.

If I were in the US. I would love to join
the proto group as well. pity me ):
post #118 of 2213
I have good news my friends!
Second proto is pleasing my ears as I type with ZERO hic-ups.

First impressions: Definition. Someone asked for me to compare to My soha+jisbos.... There is one big difference. this amp drives my 32ohm cans and my 600ohm akgs with no problems. the soha doesnt like the akgs.


More to come....
post #119 of 2213
> forsakenrider :I have good news my friends!
Second proto is pleasing my ears as I type with ZERO hic-ups.

First impressions: Definition. Someone asked for me to compare to My soha+jisbos.... There is one big difference. this amp drives my 32ohm cans and my 600ohm akgs with no problems. the soha doesnt like the akgs.


GREAT! Maybe some pix after a bit...

> dracoV:So intriguing ... That's a beauty.
cfcubed, that's a very neat AMP. I like the Chrome ring. Where did you get it and how much?
I like to have a couple of that ring as well.


Thanks! WRT tube protectors see this post
post #120 of 2213
Quote:
Originally Posted by cfcubed View Post
Thanks! WRT tube protectors see this post
Is a "set" just all the parts to make one tube protector?
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