Amp Camp Amp - ACA

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#2,941
ernesternest said:
My ACA is housed in a 2U /300 Mini Dissipate. Powered by 19V,with R12, or R15 mod - I forgot, it never gets hot. I can permanently lay my hands on the sink. Powered by 24V, without resistor mod it shouldn't be much of a difference. I suppose, the ACA mono block uses a 2U /250 heatsink.
The only downside of the 2U /300 Mini Dissipante is, you have to rework the upper and lower guide rails, since the vertical dimension of the pcb plus fets is too big. An angle grinder is your friend.
Tonight I'll try the 24 V.

Cheers Ernst
Click to expand...

So, from your experience and heatsink sizes, it sounds like the 3U / 250 could work well without having to modify for mounting. Perhaps even 3U/200.

However, the 2U height would be perfect for a spot on the top of my console, so I would be interested in knowing more about what you mean by reworking the guide rails. Any photo? My guess is that it would require grinding some of the rail to make room for the PCB to mount flat against the side, no?
 
#2,942
zekeblue said:
So, from your experience and heatsink sizes, it sounds like the 3U / 250 could work well without having to modify for mounting. Perhaps even 3U/200.

However, the 2U height would be perfect for a spot on the top of my console, so I would be interested in knowing more about what you mean by reworking the guide rails. Any photo? My guess is that it would require grinding some of the rail to make room for the PCB to mount flat against the side, no?
Click to expand...
Yes, you are right. Short side of pcb + part of fet is about 70 mm. 2 U sink has got a height of 8 cm. So you have got to make some cutouts for the fets and the bolts.
Today I completed my 24 V psu. Without the resistor mod the sinks get only handwarm. Consumption is by 55 W. Me happy!
 
#2,946
Dennis Hui said:
Zeke, I recommend you look at the interior dimensions to see if what might
be appropriate for you. For example, what kind of power supply might you
put in, the size of caps you intend to use, etc, all come into play.
Click to expand...

I'm starting with the ACA kit as it came and power supplies will be external, so I was thinking it is pretty much a standard thing. As you can likely tell, this is my first attempt at building something like this, so it is all new.

Another way for me to determine if the 230mm width (150mm internal) is sufficient is to understand more about requirements. I can easily determine the space each board would take once mounted. If there is only a bit of space between the tops of the caps of each board, is that a problem? As long as they are not touching each other or should there be a minimum of 50 or 60 or 70mm of space between them?

I'm not home to measure right now, but I would think the populated boards wouldn't occupy more than about 50mm of the chassis' width each, which would leave 50mm clearance between them. I'll get a precise measurement when I get home.

I think there is plenty of room in depth for clearance of switch and jacks with their wiring given the need for ample depth to give big enough heat sinks.
 
#2,947
zekeblue said:
I'm starting with the ACA kit as it came and power supplies will be external, so I was thinking it is pretty much a standard thing. As you can likely tell, this is my first attempt at building something like this, so it is all new.

Another way for me to determine if the 230mm width (150mm internal) is sufficient is to understand more about requirements. I can easily determine the space each board would take once mounted. If there is only a bit of space between the tops of the caps of each board, is that a problem? As long as they are not touching each other or should there be a minimum of 50 or 60 or 70mm of space between them?

I'm not home to measure right now, but I would think the populated boards wouldn't occupy more than about 50mm of the chassis' width each, which would leave 50mm clearance between them. I'll get a precise measurement when I get home.

I think there is plenty of room in depth for clearance of switch and jacks with their wiring given the need for ample depth to give big enough heat sinks.
Click to expand...

OK! I think I got that last bit here myself. Each of the mono chassis from the ACA kit is 75mm wide internally. So, putting the two mono chassis together we've got 150mm width for both channels. Depth is 200mm. So it seems to me that the narrower 230mm wide 2U Mini Dissipate will do the trick. Depth might be fine at 250mm, the 300mm to be confident.

Seems obvious looking back! 🙄
 
#2,950
Hi guys,
I am looking at building this amp, although I would be like oking at a stereo set up in the same housing instead of the dual monoblock. I noticed the dual monoblock uses a power supply to each block, and needs about 2 amps (according to what I read). Is there any reason I couldn't use a 19v 4.62 amp power supply (or something similar) to run both channels? I have searched but havnt seen an answer. Curious if there is a genuine reason, or just need to match the power.
Cheers
 
#2,951
nick140795 said:
Hi guys,
I am looking at building this amp, although I would be like oking at a stereo set up in the same housing instead of the dual monoblock. I noticed the dual monoblock uses a power supply to each block, and needs about 2 amps (according to what I read). Is there any reason I couldn't use a 19v 4.62 amp power supply (or something similar) to run both channels? I have searched but havnt seen an answer. Curious if there is a genuine reason, or just need to match the power.
Cheers
Click to expand...

No problem using one 19V 4.6A for both channels, because one channel draws about 1.5A, so your are fine.
 
#2,952
yeah, We did want to have the dual monoblocks so we settled on 2 PSU's and then I found the big 4+ amp PSU's were the same price as smaller ones so figured they would be less stressed-just loafing along.. AND that did offer the option of just using one if you want.

so the answer is yes..
 
#2,953
Howdy campers! 😀

I have a couple of questions regarding PSU & grounding & hoping some of the more electronically astute can help me out.

First, I'm building a dual mono ACA running on 32V. I'll be building a separate PSU (typical Pass CRC) connected to the ACA via an umbilical (4 wires + GND). I presume that, unlike the SMPSs, I can't leave the PSU powered up when the amp is turned off; the PSU will require it's own on/off switch. Am I correct? If so, kind of a bummer... I'd like to avoid having to switch the PSU on & off. Can anyone suggest an elegant solution that will let me switch the PSU on/off remotely from the ACA?

Second, grounding: My plan is to have the safety earth, plus the CL60s (connected to the PSU grounds), plus the umbilical ground wire to the ACA all connected at a single point to the PSU chassis. The other end of the ground wire will connect to the ACA chassis, but how should I ground the boards? Do I have to? The official boards are not grounded, but then the SMPSs don't have safety grounds. I don't want to create ground loops. Any suggestions?

Thanks,

Chuck

PS build thread here: ACA Concept II
 
#2,955
Haven't built the psu yet. The "bummer" part is having to turn the psu on and off, because I had hoped to put it in a hidden, less accessible place. It has nothing to do with the performance of the psu, which I expect will be fine. The bleeder resistor is part of the reason for the question, since with the bleeder the psu will always be loaded and the caps will continuously charge & discharge. So I guess the question is: without the bleeder resistor is it ok to keep the psu on when the amp is turned off, or would that be detrimental to the filter caps? And if it is detrimental, is there an elegant way to switch off the psu from a switch located on the amp? (Running mains voltage through the umbilical would not be elegant, to say the least.)

The psu won't be ready before BAF, so if I bring the amp it'll be running off the Variac.
 
#2,960
Hi All
I posted on another thread and was directed to this. I have a camp amp (circuit board states 1b). I am having difficulty as with a valve pre-amp (based on the Maranz 7) I still don't get adequate output even at full volume. This is with 94dB sensitivity speakers. My 5w valve amp has no problems so it appears there is a problem with input sensitivity.
Does anyone have any ideas as I feel this is a great amp.
Thanks and Regards
Chris
 
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