@Nelson Pass I ran into a Nakamichi PA-5ii near me today for 500.00. Is that thig to old to be worth the money, or should I go get it? It's near mint. Sorry to pollute the thread.
@tuyen: You might need to go 2K on the trim pots. See here: https://www.diyaudio.com/community/threads/diy-aca-mini.379037/page-80#post-7209725
Does it make sense one channel is biasing fine and other channel needed different value trim pot, even though the fets are meant to be matched?
OK, ignore my previous arrangement mentioning VO and VB
Papa should include these points in schm, dammit
anyway, with mosfets out of circuit
both trimpots to zero
connect black probe to + Rail, red probe to G pin of Q3 (most left pad) , write voltage
connect black probe to GND, red probe to G pin of Q4 (most left pad) , write voltage
both trimpots to max
connect black probe to + Rail, red probe to G pin of Q3 (most left pad) , write voltage
connect black probe to GND, red probe to G pin of Q4 (most left pad) , write voltage
all ref to this, taken ditto from article
Hey there, I kinda knew that going in, the bottom is drilled out to allow air to come in from under the board and disperse throughout. The feet on the bottom raise it an inch off of the other component, which is not used at the same time. I may completely remove the lid as well. I do have a temp gun and will be checking on it. That box was on my desk when I first started reading about the mini, and it made me pull the trigger on it. I figured I had to try and get it in there. It may not stay forever.
I like the switch and light on the front. How does it look on the back?
I am sorting out a wooden box for a base with connections built into the back of the box. Maybe a potentiometer on the front if tests work well.
I am sorting out a wooden box for a base with connections built into the back of the box. Maybe a potentiometer on the front if tests work well.
I don't think that is quite enough money to accomplish a whole first-watt build. At least not any of the 25-watt variants without scrambling or making a chassis. Especially with the price increases of parts etc over the past few years.
I know I am not Pass but I have heard the PA-5II. it is a nice-sounding amp. I like the way a lot of these class A first-watt amps sound better. If the PA-5 had the front end separate from the amp board, I would say grab it as you could do a lot with that.
I know I am not Pass but I have heard the PA-5II. it is a nice-sounding amp. I like the way a lot of these class A first-watt amps sound better. If the PA-5 had the front end separate from the amp board, I would say grab it as you could do a lot with that.
Nice... I got a B1 in a humidor... it runs great... hasn't burned the house down yet.
I got a large wine bottle box, Daou, fits 6 bottles, with a hinged top. 12"x15"x9". The plan is to put an already built Mini in there. I figure I can always open the lid when I play the amp.
Cigars, wine and 2nd harmonic go together hand in hand.
The PA5 and PA7 are much more desirable in their Mk I iterations... the ones that prompted the copyright lawsuit. The PA7-I, in particular, is considered to be the poor man's amplifier for Maggies. Unfortunately, they are no longer "cheap". I figure you could build the A2s kits for less than a PA7-I.
I forgot to open the lid when I fired it up tonight, playing at 85 db on some KLF-20's. Highest temp is 170 per IR on the heatsink. Is that horrible? I opened the lid and will retest.
105... at the end of the night. The amp sounds fantastic. Jumpers in is the only way I have listened to it so far. I will post some back panel and bottom pictures tomorrow, and pull the jumpers.... Thanks all, as always here.
To run a stereo ACA mini at the bias levels Pass recommends? I wouldn’t recommend it.
In Pass‘ ACA mini article (even without knowing anything regarding the bias), Pass recommends a regulated 24V DC, 90 watt Meanwell supply.
The WHAMMY however, uses a 25VA (i.e. close to 25 watts, but not exactly) Toroid for the stereo headphone amp.
Best,
Anand.
In Pass‘ ACA mini article (even without knowing anything regarding the bias), Pass recommends a regulated 24V DC, 90 watt Meanwell supply.
The WHAMMY however, uses a 25VA (i.e. close to 25 watts, but not exactly) Toroid for the stereo headphone amp.
Best,
Anand.
He changed to a smaller one. The store kit comes with a 48W brick. That's for 2 channels so 1A each. The WHAMMY PSU will do 1A no? So 2 half WHAMMY PSUs should be good?
Thanks for clarifying. I didn’t know the store kits come with a 48W SMPS. That changes things.
If you have (2) Whammy PSU’s, i.e. (2) of the 25VA Toroids, then that may be doable.
I usually try to be conservative, given that the encapsulated Toroids in the Whammy (i.e. not Antek) will heat up since they don’t have free ventilation. This being Class A and all where the bias is constant. Usually 50% is my rule. In example, my MOFO build uses a 120VA SMPS for a circuit that requires 60 watts (24V @ 2.5A). Even then the SMPS sits at 40 degrees C with the amp cover open and close to 50 degrees C with the cover on.
I haven’t looked at the bias requirements for the ACA mini, but I probably should…better yet, I’ll hook it up to my bench supply (which measures the current draw) once I’m done building it.
Best,
Anand.
If you have (2) Whammy PSU’s, i.e. (2) of the 25VA Toroids, then that may be doable.
I usually try to be conservative, given that the encapsulated Toroids in the Whammy (i.e. not Antek) will heat up since they don’t have free ventilation. This being Class A and all where the bias is constant. Usually 50% is my rule. In example, my MOFO build uses a 120VA SMPS for a circuit that requires 60 watts (24V @ 2.5A). Even then the SMPS sits at 40 degrees C with the amp cover open and close to 50 degrees C with the cover on.
I haven’t looked at the bias requirements for the ACA mini, but I probably should…better yet, I’ll hook it up to my bench supply (which measures the current draw) once I’m done building it.
Best,
Anand.
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