For anyone who might be interested: Nelson Pass-designed ACA amplifier kit "back in stock" :)

mhardy6647

Some of you ("us") have an interest in low power, high performance amplification. Designer-guru extraordinaire Nelson Pass has been an enabler for those willing to turn to the soiled solid state in pursuit of fleapower Nirvana.

Some years back, Pass helped design and develop a simple Class A stereo solid state amplifier on a PC board. The design was turned into a kit designed to teach folks to build and appreciate such an amplifier at "Amp camps" -- thus, the Amp Camp Amplifier (ACA) came to be!

The ACA kit is commercially available but has been out of stock for a while. Overnight I received an e-mail announcing that an updated version of the kit was now back in stock!

https://diyaudiostore.com/products/amp-camp-amp-kit?utm_source=ACA+Back+in+Stock+Notification+List&utm_campaign=0411d3ac9e-EMAIL_CAMPAIGN_2018_03_26&utm_medium=email&utm_term=0_72286d7b2a-0411d3ac9e-261238033&mc_cid=0411d3ac9e&mc_eid=93022bf314



Just thought it worthy of mention.

Rock on with your respective bad things

________________
* Disclosure: thanks to the mad skilz of this forum's ALL212 and the generous beneficence of another Forum member (who will remain anonymous unless he cares to reveal himself), a fancier morph of the original incarnation of this amp is 'in residence' at the Hardy household in the wilds of northern NH. This is a very cool little amplifier for those who can work with ca. 5 watts per channel.

vcwatkins

Thanks @mhardy6647! Placed an order.

maxward

Thanks! Ever since I retired I’ve been itching to build or modify something. I have some Dynaco kits under my belt, but that was a very long time ago. Nelson Pass spoke to an audio club I belonged to in Portland and I always wanted one of his designs.

mhardy6647

Nelson is a clever fellow who knows good sound and is skillful enough to get to it. Best of all, he shares his talent, skill and enthusiasm with the DIY community -- and doesn't look down his nose at those who cannot afford the top-dollar hardware.

Can't say enough good things about the guy based on what I know of him.

I mean, anyone responsible for the El Pipe-O subwoofers is my kinda guy.



http://www.firstwatt.com/pdf/art_elpipeo.pdf

Clipdat

Interesting:

"Power per channel 5 Watts per channel (That's 92 decibels coming out of your speakers, assuming you're listening from 10 feet away with 91db efficiency speakers. More than 2 hours at this volume level exceeds occupational safety limits, is more than adequate to annoy your neighbors, and certainly enough to enjoy your music at normal listening levels)"

mhardy6647

The daily driver at my house is 3.5 wpc, you know?
The loudspeakers are on the order of 102 dB SPL sensitivity at 1 meter for 1 watt input power.

There are different pathways to Nirvana.

Viking64

mhardy6647 wrote: »

There are different pathways to Nirvana.

You should have ended this comment with: "Boot to the head."

maxward

Currently sold out! Snooze you lose.

Tony M

And I was going to order one too.

mhardy6647

already?!

maybe the website itself hasn't been updated(?!?)

maybe...

Clipdat

Earlier it was accepting orders, now it's listed as sold out.

mhardy6647 wrote: »

already?!

maybe the website itself hasn't been updated(?!?)

maybe...

heiney9

All sold out again!

Dammit, I wanted to build this.

mhardy6647

dang! sorry, folks

heiney9

Not your fault.....they sold out fast! I put my email out there for the next batch. Very cool kit and chassis.

kharp1

Clipdat wrote: »

Interesting:

"Power per channel 5 Watts per channel (That's 92 decibels coming out of your speakers, assuming you're listening from 10 feet away with 91db efficiency speakers. More than 2 hours at this volume level exceeds occupational safety limits, is more than adequate to annoy your neighbors, and certainly enough to enjoy your music at normal listening levels)"

Screw 'em, they shouldn't have moved in next to me!

voltz

These would have been great with my Full range Speakers that are 94 dbl.

My Omega Super 7 Monitor MK2's

mrbiron

Scat....I would have ordered immediately because I can't find time to drive North...

mhardy6647

mrbiron wrote: »

Scat....I would have ordered immediately because I can't find time to drive North...

I've noticed that -- I may have to avail myself of the United States Postal Service. I gots mad packing skilz...

mrbiron

I know I know...
I'm a tease with the likes of "yeah, let's set something up for this fall" or "put a date on a calendar and I'll make it work"...

Is retirement at 33 an option?

mhardy6647

Depends on whether spending one's golden years livin' in a cardboard box under the freeway is an appealing lifestyle choice. I'm speculating here. I mean, I reckon it's a realistic choice for, say, that Zuckerberg guy. In fact, perhaps he's considering retirement these days...

mrbiron

Sounds fun. Now I just have to find a bridge worth dwelling under.

verb

@mhardy6647 are these a SE design?

mhardy6647

verb wrote: »

@mhardy6647 are these a SE design?

Yes.

http://www.firstwatt.com/pdf/art_amp_camp_1.pdf

verb

Aw man! I snoozed and I loozed! gonna get on the notification list now!

Clipdat

Sorry bro, I would've ordered one for you had I known you wanted one. I was going to order one but I don't own a soldering iron, and also my testicular fortitude is low.

I didn't have the balls to attempt it.

verb wrote: »

Aw man! I snoozed and I loozed! gonna get on the notification list now!

verb

Thanks man. I hear ya. I’m intrigued by the SE or SET amp discussion. Nice way to dip the toes in. Soldering is not that bad BTW. Pretty easy in fact once you get some practice.

mhardy6647

no triodes in an Amp Camp Amp
Three "elements" in a transistor, but it just ain't quite the same thing

If you want to dip your metaphorical toes into the SET water, here're a couple of nice options. L'il pricier, though.

https://bottlehead.com/product/single-ended-experimenters-kit-3-for-headphones-sensitive-speakers/


(Compactrons, baby!)

https://bottlehead.com/product/stereomour-ii-stereo-single-ended-integrated-2a3-amp/

mhardy6647

PS Yeah, soldering is not difficult at all. Just wear pants when you're soldering -- that stuff gets hot.

A PC board based kit like the ACA is particularly easy; point to point requires a little more manual and mechanical dexterity.

There are some PC board based SET amp kits, but they're more like semi-kits* (i.e., not all components supplied), so they require a little bit more of the buyer/builder.

Here's an example, FWIW (and since we're -- sort of -- on this subject!).

http://store.triodestore.com/diytubegetsetgo.html
http://www.diyaudioblog.com/2012/03/diytube-getsetgo-single-ended-amplifier.html

This is sort of a hybrid between PC board and point to point construction. The 6B4 output tubes used by this amp are a "modern" variant of the classic, venerable 2A3 direct heated triode. The 6B4 differes from the 2A3 "only" in its base configuration (octal vs. 4 pin) and requiring a "modern" 6.3 volt filament voltage (vs. the 2.5 volt filament of the 2A3). It's still a gen-u-ine direct-heated filament triode, though.



Current (or at least recent) production Russian 6B4s are still available, too -- though not necessarily very inexpensive. https://www.tubesandmore.com/products/6b4g-sovtek

_____________________
* EDIT There might be full kit SET amps available with all of the guts on a PC board... but offhand I cannot think of any.

FestYboy

Wish I had the editing software to make an instructional video for the forum. The key is tinning the pieces to be soldered and heat control, especially when working with PCBs.

mhardy6647

FestYboy wrote: »

Wish I had the editing software to make an instructional video for the forum. The key is tinning the pieces to be soldered and heat control, especially when working with PCBs.

I wish you did too

... and to use very good quality solder and a good soldering iron.

The soldering instructions that will be found in the instruction manuals for old Heathkit or EICO kits are good. Yeah, a video would be better, but they are good.

The trick, I'd opine, is to work (fairly) hot and fast (as fast as possible, that is) for best results, and to hold the joint nice and steady when/while the solder cools. OK I guess that's two tricks. One of the pitfalls IME is to accidentally jiggle the joint when it's still hot; this causes nasty 'cold solder' crystals (or whatever) to form.

I do agree that temp controlled is the way to go for any serious work.

Some components (particularly transistors, diodes and ICs) will benefit from heat sinking while soldering, too.

heathkit howtosolder by Mark Hardy, on Flickreico solder joints by Mark Hardy, on Flickr

Like anything else, the best way to learn to do it is to find a mentor and learn at his or her feet (so to speak). Failing that, trial and error (sometimes referred to as trial and success) is also a valid approach. Remember, anything that does not kill one makes one stronger.

EDIT:
PS Soldering irons aren't the best for certain applications (e.g., soldering down multisection "can" caps, soldering ground busses, and - to some extent - for cable construction, too). At times like that, it is still (IMO) hard to beat the good old time soldering gun.

verb

mhardy6647 wrote: »

no triodes in an Amp Camp Amp
Three "elements" in a transistor, but it just ain't quite the same thing

If you want to dip your metaphorical toes into the SET water, here're a couple of nice options. L'il pricier, though.

https://bottlehead.com/product/single-ended-experimenters-kit-3-for-headphones-sensitive-speakers/


(Compactrons, baby!)

https://bottlehead.com/product/stereomour-ii-stereo-single-ended-integrated-2a3-amp/

Yep. I was intrigued by that amp mentioned by you on another thread. And equally touched by your story as to how the kids put it together. Good memories! I'm sure every time you play it you reminisce. Very heartwarming!