Amp Camp Amp Kit 1.6/1.8

[astromo]

Mark, for your chunky resistors, you might find this gear handy:
CER-3 Essentra - Spacers, Standoffs - Distributors, Price Comparison, and Datasheets | Octopart component search
Haven't used them myself yet but it's there in the back of my mind.

 

[Puma Cat]

Puma,

Yes, you can convert the amp to mono but it is by simply flipping the new 3-way switch. Take a look at the wiring diagram pdf in the new build guide here:
1.8 Build Guide

Also, if you use a balanced connector, you will get mono (as long as you have the switch in the correct spot.) No internal work needed.

For power supply, there were some mentioned in the build thread. The only one I remember by name is the SLB (Smooth Like Butta) but I imagine there are many more. It's a long read but well worth it.

Hi bhjazz,
Thank you very much for the information and for the link to the PS thread.

This community is great...thank you!

 

[Puma Cat]

The current PSU available in the complete kit (and separately) is a 24v Meanwell SMPS PSU which is a rather significant upgrade over the original 19v generic PSU, being much quieter electrically, and gives a bit more muscle to the ACA, while unfortunately adding to the cost significantly when it was introduced in the 1.6 version.

Thanks, Variac, for the info.

I plan to use the supplied Meanwell SMPS for my ACA in the interim, but over the longer term, I'd like to obtain or build a nice clean LPS for it. Primarily because SMPS are insidious for putting out high-source impedance AC leakage currents into any system they are connected to, and this leakage current causes increased jitter and most notably, increased clock phase noise for digital streaming systems. Given all the work I've done for my digital streaming front end, including using audiophile-grade FMCs and optical fiber to stream from the music server 40 feet away, using a SMPS kinda defeats all that.

I'm getting pretty far off-topic here, but that is why I inquired about an LPS for the ACA 18.

 

[ranshdow]

Hi, new to the board and returning to hobby electronics after maybe 30 years. I just finished building the ACA 1.8 (it took me two full days) and I've been listening to it in my system for the past couple hours. I'm very impressed by the stereo separation and sound stage in comparison to my Rega Brio. One question- the entire chassis is hot to the point that I can only touch any part of it for less than a second (faceplate, top plate, heatsink fins). I'm using the Meanwell 24V power supply and my input is not at full volume. Is this amount of heat normal?

 

[Mooly]

Heat is very subjective but yes, its normal for it to run HOT. This is assuming you have used the recommended case and heatsink (the full kit).

Each channel dissipates over 35 watts (so 70+ watts in total).

The amp will actually run cooler the louder you play it, although with normal music you probably wouldn't notice, but that's the way it is... welcome to Class A

 

[ranshdow]

Thanks Mooly. Yes I'm using the full kit with the Italian chassis.

 

[Mooly]

All good then

A good analogy is to think of a fairly powerful mains soldering iron of say 40 watts and then imagine a couple of those clamped to the case... how hot is that going to get after a few minutes... pretty HOT!

 

[motospark]

Wow, thanks.

Mark, for your chunky resistors, you might find this gear handy:
CER-3 Essentra - Spacers, Standoffs - Distributors, Price Comparison, and Datasheets | Octopart component search
Haven't used them myself yet but it's there in the back of my mind.

I will order a few and check them out, thanks for the suggestion.

Mark

 

[lt_texan]

The heatsink metal right at the transistor's edge is measuring 45C.

That's after 10 minutes warm up with an infrared gun.

I think I'm okay with these smaller heatsinks.

Dan

I found a meat thermometer works good too. At ten seconds you’re probably around 60C -140F. If this is at the transistor itself I would say you’re running at what most people do in the forum.

Keep in mind that although most of the heatsink will be at the same temperature, the transistor case is noticeable hotter since the interface with the heatsink has poor conductivity even with paste and mica which are quite a bit better than silicone pads. And then the transistor die itself would be even hotter because it’s conductivity to the base plate is also not great.

150C is the maximum temperature of the die. If you look in the data sheet you’ll see a chart of the maximum casing allowable temperature per current being drained. You see that the hotter the die is, the cooler the casing must be kept at. That’s because heat takes time to transfer and the die is hotter than the case.

 

[astromo]

You'll probably get a more reliable read after an hour (of course with the lid on). I wouldn't be surprised if the temp increased 5 °C (or so) from the measurement you're reporting.

 

[Steve Luck]

You need to consider the room temperature. Right now in NZ winter and poorly insulated NZ house the surrounding air is pretty cool and the whole setup feels much cooler than it did in the summer. One of those USB powered fans to get the air moving in summer is a consideration.

 

[phomchick]

I have a pair of 1.6 boards built up and lying around. To finish the project, I need the chassis and the chassis hardware. I think I saw a post with instructions on how to get a chassis, and a BOM for the hardware. If that was not my imagination, any pointers?


Thanks!

 

[astromo]

phomchick, did you check the store?

 

[Alan4411]

The heatsink metal right at the transistor's edge is measuring 45C.
That's after 10 minutes warm up with an infrared gun.
I think I'm okay with these smaller heatsinks.
Dan

10 minutes is not long enough for this test. Leave it on for an hour, then measure your temps again. You need to get to the point where the heatsinks get to their maximum stable temperature. If you are going to fit a bottom and a lid that will increase the temperature too.

I still think you will need a bit more heat sinking or fan...

 

[phomchick]

phomchick, did you check the store?

Aha! That is where I originally saw the break downs, but I didn't scroll down far enough the last time I looked. Thanks.

 

[Variac]

One question- the entire chassis is hot to the point that I can only touch any part of it for less than a second (faceplate, top plate, heatsink fins).....Is this amount of heat normal?

So that seems a bit hotter than I'm used to seeing. Of course I lived in SF, not further south where it could be quite a bit hotter. People tend to forget that ambient temps vary CONSIDERABLY throughout the world.Think of the guy from Mumbai who wrote once..

My experience was with a friend who hosted the original Amp Camp in Santa Rosa. It gets pretty hot there at that time but the completed amps being tested in the shade weren't excessively so. However the host had his ACA in a bookshelf that had a back and was about 24" wide. the shelves were about 12" apart vertically. His amp was BLAZING hot! So please don't put your ACA(s) on a shelf with sides and top and a back panel if you are in a warm climate. It makes a huge difference

 

[thomasnadeau]

I just built a v1.6 ACA a couple of weekends ago and this is what I measured at the heat sinks after an hour of sitting idle on the bench. This is within a few degrees or so of what the other 2 pairs I've built. The exception is the earliest version which used less current so dissipated a bit less. The headline here is that these idle pretty hot but are still well within the 'linear' region of the devices. If you are uncomfortable with this, do what Papa Pass has always said along the lines of, "you can never have enough head sink." and add more.

--Tom

 

[HeyBill]

Finally building my V1.6. I see that the supplied output wires (blue and Black) are 18 gage. The red B+ wire is 22 gage. They look too small to me. Am I correct? Also didn't receive the green input wire.

I have lots of wire in the back room. Just need to know the right size. Thank you, Bill

 

[lt_texan]

So what pregame is everyone using to drive your ACA?

How about one from the DIY store?

(Yes, I’m fishing.(

Thanks
Dan

 

[motospark]

I'm using.......

Hi, I'm using the Pre-Amp outs of the Parasound Hint, that is until I build a not delivered yet Korg Nutube B1 Pre-Amp Kit. I have played with the Original stock ACA 6.1 build in Stereo Mode, I will at some point Upgrade my current 1.6 to 1.8 Premium Parts and I have another New 1.8 Kit ready to go, just waiting on a few more upgrade parts. At that point I will run the ACAs as Mono Blocks.

Mark