DIY ACA mini

[triode_al]

Stan, yes those Big Farads. But then Smaller (like about 2 F, that should also have low ESR.
I also like Getzoff choice of a LiPo, but hey, then I need a metod to soft charge, a metod to decide when and how to charge (I mean a LiPo charge mgt combined with the on-off switch, a ralay or two, and a relationship with the on-off switch. I have seen designs/PCBs for that, and is complicated to breadboard. So I am very afraid for that route.

 

[brimax]

Hi, i orderd the kit and starting to read all the thread .... but it's so long 🙂
Can someone anticipate me some good preamps for driving ACA mini?
Is B1 Mezmerized good enough?

thanks

 

[rusomon]

Can someone anticipate me some good preamps for driving ACA mini?

You really can't go wrong with either the Korg B1 or the ACP+. Both sound great with the Mini. If I were pressed to state a preference between the two I'd give the nod to the ACP+, but only by a very slight margin. (I haven't tried the Mini with a Mesmerize B1 so I'll leave that one to others.)

In any event, congrats on your purchase of the Mini. Prepare to be impressed.

 

[Chris Jones KS]

Hi, i orderd the kit and starting to read all the thread .... but it's so long 🙂
Can someone anticipate me some good preamps for driving ACA mini?
Is B1 Mezmerized good enough?

thanks

I enjoy mine with my Whammy HPA but plan to experiment with adding a direct volume control to the Mini and will report back. Others have done it in this thread and didn’t say it was a bad idea.

 

[A Jedi]

plan to experiment with adding a direct volume control to the Mini and will report back. Others have done it in this thread and didn’t say it was a bad idea.

25K pot and you're golden.

 

[audiosteve]

Input impedance is 100k so 25k works. But I'd go even lower, like, 10k.

 

[KevinHeem]

@brimax
How about a nice ACP+. I’m in agreement with @rusomon .

 

[audiosteve]

How does the ACP+ compare to the Whammy as a pre? I assume you'd also haver to add a lower Z load to Whammy as is done with the ACP+ for pre-amp duties. I kind of like the fact that Whammy uses a bipolar supply and is DC coupled. Does anyone have any firsthand impressions? Thanks.

 

[A Jedi]

Input impedance is 100k so 25k works. But I'd go even lower, like, 10k.

You're correct. I actually used 10K. For some reason I remembered it as 25K.

 

[birdbox]

I just got my kit in the mail today and it appears the switch is "momentary" in that it goes back to centered position (off). In order to stay in the full left, or full right position, I have to hold it with my finger. I feel like this isn't correct and haven't found anything on this thread regarding a momentary switch, however, I'm pretty new to all this so I'm second guessing myself.

 

[ggetzoff]

Sounds like it’s defective, you can just wire it open or head over to Home Depot and get a cheap switch and use flying leads on it until you get a replacement.

That stinks and is very rare for a part to be defective.

 

[birdbox]

Thanks for the reply, however, I think the switch is operating per design the side of the switch shows (ON) OFF (ON). It sure feels like it was intended to be a momentary switch per design and it's possible that wasn't the type that was supposed to be in the ACA MINI Completion Kit. Again, I could be wrong here, but it's the only part I haven't soldered on yet and I was hoping to get it fired up tonight.

 

[6L6]

The switch is labeled (on) off (on)?

That is momentary, as you correctly identify, the parentheses indicate momentary, and not what should have been included in the kit.

Start a ticket with the help desk so it can be determined if this is more than one kit.

Check PM

 

[Jason]

This is an issue with the new batch of kits. All affected customers have been contacted to confirm their address for a replacement switch to be sent. Apologies for the trouble, we'll get these out ASAP.

 

[birdbox]

Once I got the proper switch I did run into an issue that I'd like to share to help with other noobs like myself out.

I noted the LED blinking (blinks) once I applied power and turned the switch to on. It blinked every few seconds and it was clear something wasn't right. After a little investigation, I found that I had flipped the Q3 and Q4 MOSFETs on one channel. I searched this thread high and low and saw no mention of a blinking LED, so I figured I'd share what occurred in the hopes of helping someone else out. As soon as I recognized that I had one channel incorrect with the MOSFETs, I made the fix and it worked just fine. So, if you have a blinking LED, first thing you should do is verify those Q3 and Q4 MOSFETs are in the correct position.

Thanks to 6L6, ggetzoff, and Jason for the quick follow up when I ran into the switch issue.

Best,
Dan

 

[Nelson Pass]

The blinking led is the power supply in "startup test mode" where the supply is looking for load issues on startup. If the test pulse fails it will try repeatedly in pulses, hoping to charge a large capacitor or clear a fault.

 

[Nelson Pass]

By way of clearing a fault at turn on, try turning the switch off for a short time and then turning it back on.
This way the pulses just charge the caps before the bias comes on.

 

[birdbox]

Thank you very much Mr. Pass for the explanation. I also want to say thank you for helping make this all possible. Your generosity to freely share your knowledge, experience, and phenomenal designs is an incredible gift.

 

[Nelson Pass]

It was something that we missed when going to a different switching supply, where the turn-on protection was slightly lower and near the edge. Some units triggered and some did not, but the few I tested were OK. With the switch initially in the off position, no problem. The subsequent rev fixed this with a resistor change.

 

[marec]

My first amp amp mini from a kit from DIYaudio (I’ve got two to build) and I’ve got a ‘noobie’ problem…
when powering up the amplifier, the voltage at vb is 24v instead of a few hundred mv. I’ve obviously got an error somewhere, but can I see it?😡
Please help!😀