There is also considerable leeway in the value and wattage rating. I suggest .68 up to 1 ohm at 2 watts will work.
If I want to add a simple Alps volume pot to the ACA Mini to make as integrated amp what value of the pot is suggested?
Thanks
Thanks
Sorry I can't figure it out from the schematic - what's the input impedance without adding a pot?
Thanks!
Pete
Thanks!
Pete
resistor going from input gate up, in parallel with resistor going from input gate down
if you post/point to schematic at which you're looking at, I can give you parts by nomenclature 🙂
if you post/point to schematic at which you're looking at, I can give you parts by nomenclature 🙂
Thank you for the help! It's very nice of you to help me learn to fish, rather than just throwing me a trout. ;-)
My guess is that you're referring to R2 and R3, and that they're in parallel, so it would be ~110k ohms. (except R4 adds a bit to R2, I would think.
Am I on the right track?
Thanks again!
Pete
Okay, I will need to learn more about R4 being nulled, and I see that I forgot to add in R1, but I'm somewhat heartened to see that my uneducated guess was close.
This is an unusually high input impedance for a transistor amp, isn't it? I'm not complaining - it will make it easier to play with different passive volume controls, like TVC, LDR, and the 10k pot suggested above.
Thank you again.
Amateur fisherman,
Pete
Could this be happening with the unit I built from the first DIY Audio Store batch? I've noticed that sometimes when, after leaving it off for a while I turn it on (via the switch) the sound and led will pulse in and out, and sound bad, if I turn the switch off and wait a minute or so it will usually turn on just fine first try.
I also get a very large thump when switching to the "off" Mini ACA. In this case I am using a Schiit SYS to switch the output from my ACP+ preamp between the ACA Mini and one set of speakers, and a completely separate ACA with its own set of speakers. No thump when switching with it on.
The way this works reliably is if you apply AC power to the supply with the switch "off" which is to the left on the switch. Then you wait a few seconds for the supply caps to charge and then you can flip the switch to "on". After that you can turn the bias current off and on as you like, treating it as a standby. If this is annoying you can raise the value of R4 so that it takes longer to come up, or get a supply with a higher current rating. Note that the higher current rating is not expected to make sonic improvement unless you are clipping into low impedance.
Also note that if you drive the input hard with the bias switch off, that signal will still bleed to the output stage and make noise, so if you are connecting/disconnecting the input sources you may want to shut down the switching supply first and let the power supply caps bleed down for a few seconds.
Also note that if you drive the input hard with the bias switch off, that signal will still bleed to the output stage and make noise, so if you are connecting/disconnecting the input sources you may want to shut down the switching supply first and let the power supply caps bleed down for a few seconds.
Thank you for the information, it sounds like I can deal with this with some small changes to usage and have some hardware options if I can't train myself properly.
@Nelson Pass Do you know when they will pop up in the store? Is the store running in lean vacation mode?Packing up the Essentials kits today, and tomorrow they go off to the store.
It takes the fulfillment house a week or so. I expect sometime next week.