Amp Camp Amp Kit 1.6/1.8

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dual mono in a mini dissipante 300?

Hi friends!

I realized there's a Mini Dissipante 230 x 300, would 2 ACA's fit into one of these?
A PCB with the transistors makes pretty much 150 mm, so it seems it would.
But would they overheat, having 2 of them being so close to each other? (And then, it would be funny to have them turned 90°, getting a cube 230 * 200 * 200 IF this form factor would exist. sigh!:yinyang: )
 
I'd say they'd get too hot but there'd be no problem stacking two 230 x 200 with no base plate on one and no lid on the other to create a linked internal space. Bit of box section ally from DIY store to fill the gap and drill a few holes job done. Buy two ACA specified cases and all the mounting holes in the heat sink will be pre drilled ready to go.
 
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What happens if I lower the bias to, say 10V? Nothing except that the amp starts to clip earlyer? And gets a bit less warm?

The heat dissipation should stay the same if you alter the midpoint voltage (bias is misleading because so many immediately think of quiescent current adjustment here).

With the midpoint set accurately each transistor dissipates the same power. If you alter the midpoint to say 6 volts then one transistor will dissipate much more power than the other due to the different voltage now dropped across each device. The current flow is unaltered.

The one with least voltage across it will be cooler. The total power dissipation of the two devices added together remains the same.

Just in case somebody else will have the same question:
I just found a nice graphic "explanation" of it at the german wikipedia ( Arbeitspunkt – Wikipedia ):

Arbeitspunkt_Transistorverst%C3%A4rker.png


Thank you, Mooly, for your explanation, which I only now begin to really understand!
 
As I continue my intermittent troubleshooting it seems one of the most obvious issues I have is that on one board Q1 S is registering 24v when it should be zero. On close inspection nothing seems to be obvious on the board itself. Could this instead be an issue with how I have attached the ground wire?
 

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You need to make a really good solder job where the 2 black wires and the 'twisted' wire meet the input connector. From the picture it does not look soldered at all.
The other solder joints do not look special either. They look 'blobby'. You should hold the iron against the joint a little longer, then the solder will flow into and around the joints when you get it right.
 

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The source of Q1 should be connected directly to ground and so I suggest you check carefully where you are measuring your voltage from... in other words where the black meter lead is connected to.

An ideal point would be the outer part (ground) of the RCA input sockets or the positive speaker terminal assuming you have wired these as per the instructions.
 
I want to donate ACA kit To my college Electronics 101 class

My first community college is underfunded and understaffed where I took my basics electronics classes at laney College Oakland. I would like to donate my time and some ACA kits to the class, already have approval from my Former instructor.
I do know the majority transistors from eBay Chyna are knock offs or lesser known Chinese companies that are not Semi South ON , Fairchild or Vichy. And well aware 100% of the Toshiba‘s are fake counterfeit but do they work good enough for a free kit to students or does anybody know of dropping replacements without doing the math to change resistors because that’s where I am very weak.

The attached photo files of resistors IRFP240, IRFP450, 2SK170
I’m willing to spend the money on the fake resistors Or third-party not so well known semiconductor company (they don’t always have to be a big well-known brand name do they ?) as long as they work. Can’t beat the price probably don’t sound as good but I will have a authentic demo in the class to show the difference and I’m willing to experiment.

For the class I was going to provide to demo options one (point the point construction ) and the other on Perfboard.

I was going to link the amp camp amp V1.6 build guide link to the students from there they can make up their mind if they want the homemade donated kit for free and they have the option to purchase the boards if they want.

The IRFP240 were $24 to $37 for 50 PCS One even claims they are Fairchild.
PHP:
 

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ACA 1.6 stereo start up noise

Hi, I just bought an owner assembled 1.6 version stereo version with the Meanwell 24 volt power supply and it makes an odd noise on start up that I do see mentioned in briefly looking around. Can anyone please tell me if this is something I should be concerned about and do they all do it? I'm sorry I am so busy to explore fully, on my own at this time, but want to see if I should approach the seller asap as it being undesirable like this, especially should I want to re-sell in the future? Thanks SO much for any and all thoughts on the matter? Kindest Regards, Rob
 
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Hi, I just bought an owner assembled 1.6 version stereo version with the Meanwell 24 volt power supply and it makes an odd noise on start up that I do see mentioned in briefly looking around. Can anyone please tell me if this is something I should be concerned about and do they all do it? I'm sorry I am so busy to explore fully, on my own at this time, but want to see if I should approach the seller asap as it being undesirable like this, especially should I want to re-sell in the future? Thanks SO much for any and all thoughts on the matter? Kindest Regards, Rob

Answered here :)
Amp Camp Amp - ACA
 
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2c

... especially should I want to re-sell in the future? Thanks SO much for any and all thoughts on the matter? Kindest Regards, Rob

Hi Rob
Your question being already answered, I may just give the unrequested advice to be a bit forgiving, and take your time to listen a little bit to this fine, sympathetic little amp. It's a joy. Well, I enjoy it very much.
david
 
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little bit lost on PSU

Hello everyone!

I'm in position to start my second ACA, it's gonna be a dual parallel with varying parts (according to TungstenAudio), custom chassis and the universal PSU from diyaudio store (Universal Power Supply – diyAudio Store)...

Building the ACA isn't a problem, but concerning the PSU, I'm a bit lost, I don't see my starting point. Is there someone whose footsteps I could follow? (building this PSU for ACAmp)?

Should I begin with finding the right toroid, and work myself along the path?
Sourcing the parts isn't the issue, but I'd like to order everything in as less batches as possible, because the shipping costs are... boutique-quality.
Where can I find information about which parts to use / values to adapt?


My first ACA plays and plays and plays, it's pure bliss. (Except when the records are bad)


thank you!
david
 
Amp Camp Amp V1.6 - Step 42 - re Blue & White Wires

At Step 42 the blue & white wires are shown twisted together. Is this necessary because I have need to only have part of these wires twisted together (so I can vary R11 to suit an unusual pre-amp I plan to use. These are the wires that run from the white & red RCA jacks to the PCB's.

Step 30 makes it clear that the 2 red wires from the centre pin of the barrel connector to the black front panel ON-OFF switchI assume to limit noise or electrical interference, but does this also apply to the blue and white wires?

Thanks.
 
At Step 42 the blue & white wires are shown twisted together. Is this necessary because I have need to only have part of these wires twisted together (so I can vary R11 to suit an unusual pre-amp I plan to use. These are the wires that run from the white & red RCA jacks to the PCB's.

Step 30 makes it clear that the 2 red wires from the centre pin of the barrel connector to the black front panel ON-OFF switchI assume to limit noise or electrical interference, but does this also apply to the blue and white wires?

Thanks.

There is no real need to twist any of the wires together. The red ones are purely for neatness and mechanical stiffness.

Just keep the blue and white input wires close to each other if you cannot twist them, but it will not make any difference.