ACA V1.5 Illustrated Build Guide

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< munch >

EDIT: Please see this post for an example of how you can make the 1.0 or 1b (or 1.1 given away at Burning Amp '17) fit in the new 2U profile: Amp Camp Amp - ACA

(Also added as picture)

I'm famous! 8) The photo is of my amp, and I had measured, re-measured, then ordered the 2Ux300 Dissapante chassis. When it arrived, I realized it wouldn't quite fit. So I re-located the MOSFETs and drilled holes where I needed them and soldered on some heavy gauge wire. The chassis is nice and cool (about 41-42C).

By my math, a 3Ux300 should have about the same fin temp (with 2 ACAs bolted to it) as the original 2Ux200 chassis did with just one ACA bolted to it.

As a side note, I did this with a hand drill on the balcony of my apartment, not in a shop with a drill press. Don't be afraid, one wrong hole won't kill you. Dig in and start making chips (metal shavings). I'm just a software weenie, so this has been a blast getting my hands dirty. And I'm not sure why people keep giving the steel back-plate such grief. Made all my holes with an electric drill and hand tools. While it wasn't a lot of fun, it wasn't terrible either.
 
Reply from the couch! Mose Allison playing. It is situated underneath the preamp with the blue lights.
 

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Ok, so, just to be sure: all I have to do is start hunting for the parts as described in post 1? Would there be any hardware differences for v1.6 other than the PSU? If yes, can someone please post a heads up of which components will change?

I'm requesting this because I am probably going to have to custom order some parts in the US and find a Good Samaritan that will bring them over. So if there are any differences, it would be great to know up front.

I'm sure that I need to custom order the linear transistors, perhaps other stuff as well. Any recommended online stores or is Amazon good enough?

Thanks, best regards,
Rafa.
 
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I'm famous! 8) ...

As a side note, I did this with a hand drill on the balcony of my apartment, not in a shop with a drill press. Don't be afraid, one wrong hole won't kill you. Dig in and start making chips (metal shavings). I'm just a software weenie, so this has been a blast getting my hands dirty. And I'm not sure why people keep giving the steel back-plate such grief. Made all my holes with an electric drill and hand tools. While it wasn't a lot of fun, it wasn't terrible either.

You are - thank you for that picture (of the old board, in a 2U chassis, using leads to the mosfets). It has been a great help to many 1.0, 1b and 1.1 BAF board owners and I've linked to it from many places!

Ok, so, just to be sure: all I have to do is start hunting for the parts as described in post 1? Would there be any hardware differences for v1.6 other than the PSU? If yes, can someone please post a heads up of which components will change?

See this page for all changes since the article (under "Audible Upgrades"): ACA Upgrade Information – diyAudio Store

* Add R15, and adjust R12 to 39.2
* A 5A 19V PSU sounds great and has been making ACA owners happy for years. The 24V we now recommend is a bullet proof option, but you can use any 5A 19V or 24V PSU and adjust voltage accordingly. Start with a cheap one from a surplus shop or raid one from a dead laptop and work your way from there.
* Consider using a solder sucker and multimeter to scavenge parts from broken equipment you can get for free
 
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I know it sounds good , especially bypassed with 1uF MKC

why worry ?

OK , I confess - worried zillion years ago , tried, tested, listened for million hours various solutions ...... and decided to trust Papa ..... if I can short his cap - I'm shorting it , if I can't - MKC bypass is all I need for peaceful sleep
 
Hello once more.
...
* Add R15, and adjust R12 to 39.2
* A 5A 19V PSU sounds great and has been making ACA owners happy for years. The 24V we now recommend is a bullet proof option, but you can use any 5A 19V or 24V PSU and adjust voltage accordingly. Start with a cheap one from a surplus shop or raid one from a dead laptop and work your way from there.
...
Thanks! As I understand it, these changes are already included in the 1.5 Diagram on first page, right? So thanks a lot.

I'm diligently doing my homework here and I have a couple of questions:
  • Q1 and Q2 are IRFP240, listed model number IRFP240-ND which is now listed as OBSOLETE. Is the IRFP240PBF-ND the correct replacement?
  • Q4 2SK170 is almost impossible to find (as I noted earlier). The LSK170 replacements are really hard to find, albeit there are some available, including here in the DIY store (thanks!). What is the correct grade replacemnt? (or at least which is sent with the KIT?) The LSK170A, B, or C.
  • C1 3300 uF capacitor is also listed as OBSOLETE. There are 3 suggested replacements in Digikey, the first one (the most expensive one) is the 381LX332M050H012 which is rated for 50V, and there are two others, one from Rubycon (35MXG3300MEFCSN22X25) and one also from Cornell (381LX332M035H012) which are rated for the correct 35V. Which is the correct replacement?

Thanks very much for any insight, best regards,
Rafa.
 
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6L6

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Rafa -

1) The IRFP240PBF is the appropriate Mosfet. The PBF is the Lead-free version, and the only one that is currently made.

2) K170 B or BL grade

3)Any of the capacitors you mention will work perfectly. More voltage rating (50V vs. 35V) is never a bad thing.


Check your PM





.
 
Will SK170 grade A also work or is more Ids needed so a grade A will go into saturation when used in ACA?


I ask because I got some grade A from the store before I really knew much about JFETs. Now I know that it depends what the JFET is used for......which grade is needed. So will see if I ever find a project where grade A can be used.......
 
Thanks so much 6L6, perfect info, thanks.

I have replied to the PM like a teenager writing a love letter! Thanks so much.

Just to bring attention here to an issue in case I'm not crazy: I have a nice countdown on the DIY Store that says I have 7 hours and 40 minutes to pull the trigger on the pre-orders, yet all the pre-order pages are throwing 404s. Is there an issue with the countdown? Is the pre-ordering period closed or is there an issue with the pages?

Thanks once more, best regards,
Rafa.

Edit: Curiously enough, the items on my cart are still able to be purchased apparently, but it says Batch 2 and ships October :(
Edit 2: Everything changed in the page: countdown no longer visible, new KIT options available for Batch 2. I guess the available pre-order quota was filled or the countdown had a timezone issue.
 
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Hi Rafa. Unfortunately we had to close the pre-order early. We use only genuine parts from quality US suppliers. They only have so many parts in stock and we are going to have to wait for them to restock. We're waiting to hear back. More information here: Amp Camp Amp Kit V1.6 - Pre-Order Status Page – diyAudio Store
 
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