Amp Camp Amp - ACA

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Danger Mouse

Danger Mouse

Member
Joined 2011
PKI said:
Folks, has anyone compared ACA sound to bigger FW amps? I ma thinking of making a small amp for my friend as a present, so would like to hear something who made a comparison(I do understand power limitations etc, but sound in general). Thanks!
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Yes i have build one and compared it against F5 AJ and SYMASYM

IMO it comes from the sound side nearest to the Aleph J but without the power.
For highs and mids or with the right speaker it a wonderful amp.
I`ve sold my ACA beause i listen mostly to the J than to the F5 and then to the ACA.
So it would stayed on the reserve bank the most time.
SYMASYM is also a really good amp but not my taste at all. All my FWclones sound better to me.
 
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propitious

Member
Joined 2012
Paid Member
all212 said:
Has anyone put film caps in the camp amps yet? I thought I saw someone going to replace the 10uf caps.
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I saw no one else replied to this so I will. I replaced the 10 uF cap in each ACA with a NOS 12.5 uF oil cap that I had, fitting it in lying sideways (5" long). The sound difference is slight which backs up the claim that those Elna caps sound great. I do however think the oil caps sound just a little "nicer". That is my preference. Years ago when I had my hands on many more caps to test, I ended up thinking I like the sound of those oil caps. The key here is that if you feel like trying something, go for it, and see what sound you prefer, which might be different from the next person. Make yourself happy and have fun trying and let us know what you learn.
 
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jrebman

Member
Joined 2007
Which cap are you guys talking about? My BOM that my assistant typed up for me only shows two caps -- 1000 uF at 16v and 3300 uF at 35v.

Alsso, does anybody know what the mmaximum wire gauges for each of the external connections from the boards?

BTW, yes, the Silmics are great caps!

And one other question -- I assume the heat sinks are orientedd with the two further spaced holes towards the bottom?, correct? RReally nice enclosures..

-- Jim
 
6L6

6L6

Moderator
Joined 2010
Paid Member
Jim,

There are two 10uF capacitors in the circuit. The first is a DC blocker in series with the input, labeled C3. The other is just some local PSU decoupling near the source of the input Jfet, labeled C4.

The max wire size on the PCB is about 16 gauge.

As for heatsink orientation, it doesn't matter of you have the Mosfets up or down, the heatsink will mount to the chassis either way, and there is noting inside the chassis to get in the way. It's pretty foolproof.

- Other Jim
 
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wfr329

Member
Joined 2012
Real newbe questions

Hi gentlemen,

this is my first post. I just began assembling the ACA.

Question 1 : i have lost the parts list, i assume i can use the one in Nelson's Pass article.

Question 2 : does it matter if the resistances touch the board or they have to be elevated a little ?

Question 3 : resistances work iether way right ?

Question 4 : should i test the resistances before soldering them ?

I plan to use the ACA on Lowther DX3's.

Walter
 
S

Samuel Jayaraj

Member
Joined 2001
Though I should have done this earlier, too many constraints had denied me the opportunity thus far; but I have now completed a single-sided PCB layout for the ACA. I am going to try an SMPS as well as a conventional one to check the sonic differences. I will be using a 18-0-18 120VA torroid. I guess it is just about sufficient. I have made the provision to switch the cap bank out when using an SMPS. Made provision for a BF862 along with a resistor in the Drain.

Questions are, the value of the resistor, assuming about a 24VDC linear supply when testing with BF862?

Although I would be driving Fostex FE168Sigmas, I just thought adding a peak power indicator or clipping indicator would be added insurance. Any pointers to a circuit?

Thanks,

Sam
 
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