Generally speaking, it’s preferable to keep the smoke inside the devices…
So, first try ... second both top will be Donald and Daisy for the grand child!
I just finished building the ACA Mini yesterday, and I'm listening to some Moody Blues on it as I write this. This is the first amp kit I've ever done, and the first class A amp I've owned. The source is Tidal master streaming through a Wiim Mini/SMSL DAC with "Tube 3" enhancer. Sound is provided by Martin Logan 60XTIs. I'm amazed how beautiful this amp sounds. It plays plenty loud to suit my tastes. My wife, a confessed tin ear, even remarked how beautiful the music sounds, especially string instruments. There is a section in one song on In Search of the Lost Chord where a guitar string is rubbed - it sounded so real it startled me. My son asked me to order him one after listening.
Will this thing get better as it burns in? It already sounds amazing.
Will this thing get better as it burns in? It already sounds amazing.
Last edited:
Unless a person has hearing damage I don’t believe anybody has a “tin ear”. It really comes down to “seat time”…meaning taking time to listen and having a chance to try different equipment.
Other than the initial warm up time (maybe 30 minutes) I haven’t noticed the ACA Mini “burn in” over time. It’s really more about you getting used to the amp.
Other than the initial warm up time (maybe 30 minutes) I haven’t noticed the ACA Mini “burn in” over time. It’s really more about you getting used to the amp.
When I first sat down to listen, I was also surprised - happily so.
😎
😎
The resemblance to 6moons reviews' style of writing is uncanny.
... ACAmini has distinct advantages... no hook-up wiring and no church-bell type of ringing/echoing from those modushop cases. That's a big advantage in my book that needs to be taken into consideration.
First time builder here. I am having trouble getting one channel of my mini to bias. With both pots at maximum clockwise rotation I can reach only 11.62v and around 150mv. The other channel is fine. I have reflowed any joints that I thought might help but it has made no difference. I have zero previous experience with PCB soldering but I was pretty happy with my work overall. You may disagree 🙂. I was very careful and measured everything twice while sorting and then again on installation.
I purchased all parts from the store and I noticed that the PSU is only 2amp where I see others mentioning 3.75amp? Could I have received the incorrect part?
The offending channel is on the right hand side of the attached photos. Any advice to troubleshoot would be appreciated. Thanks.
I purchased all parts from the store and I noticed that the PSU is only 2amp where I see others mentioning 3.75amp? Could I have received the incorrect part?
The offending channel is on the right hand side of the attached photos. Any advice to troubleshoot would be appreciated. Thanks.
Attachments
I think it will help if the wipers of all the trimpots are shorted to one of the other pot terminals as per the original article. That way the trimpots will work as rheostats instead of normal pots.
Otherwise your pots may run out of travel and not be able to adjust Vb and Vo properly.
The current PCBs have no such short and it will need to be introduced by the builder.
My 2c.
Otherwise your pots may run out of travel and not be able to adjust Vb and Vo properly.
The current PCBs have no such short and it will need to be introduced by the builder.
My 2c.
@nichoch58, yes I am aware of the biasing procedure. I am running out of turns on the pots before reaching the desired values. I am following Kevins excellent video here
@Stanislav, I was under the impression that the parts in the kit are matched to the pot values so that the target values are attainable.
We are having a very cold winter here in Oz and the house was only 10C when I was biasing the first time. Its a bit warmer this morning (16C) and VB is significantly higher but I am still short of the target. I didn't expect low ambient temps to effect VB to such an extent. Perhaps I should enclose it in a box?
I dialed the working channel back to zero to test if the 48W PSU was the limiting factor but it made no difference. I am reaching 250mv now but any movement of air causes this to drop. Both pots are at maximum clockwise rotation.
@Stanislav, I was under the impression that the parts in the kit are matched to the pot values so that the target values are attainable.
We are having a very cold winter here in Oz and the house was only 10C when I was biasing the first time. Its a bit warmer this morning (16C) and VB is significantly higher but I am still short of the target. I didn't expect low ambient temps to effect VB to such an extent. Perhaps I should enclose it in a box?
I dialed the working channel back to zero to test if the 48W PSU was the limiting factor but it made no difference. I am reaching 250mv now but any movement of air causes this to drop. Both pots are at maximum clockwise rotation.
Attachments
@Nelson Pass , The bag with the FET's says for use with 1.5k to 2k ohm bias pots. And yes, they are only single turn. The pots were in the kit but I am not sure of the type.
