Well, another try, another fail.... Like I said power and bias are all good. Got louder pulsing this time, right channel only. It slowly dissapated into a lower volume, then when powering down returned to a higher volume then went lower until what ever caps ran out of juice.
@St. Peter(sburg) -- do you have the input source connected to the RCA's? If not, hook them up (before connecting the power supply to the ACA Mini) and fire it up again.
Were you playing music when the pulsing was happening? What are the final bias settings on both channels (V0, Vb)?
Were you playing music when the pulsing was happening? What are the final bias settings on both channels (V0, Vb)?
I believe to have read on some of your ealier comments that you may initialy have installed some polarised caps the wrong way.
Is that the case?
If yes:
Last but not least, is it so that at least one channel is curently working properly?
Not the most qualified person for this troubleshooting by far, merley trying to understand what may cause the problem... while more helpful people step in 🙂
Is that the case?
If yes:
- did you fire up the amp with the caps wrongly installed?
- what caps were concerned and are they related to the faulty channel?
Last but not least, is it so that at least one channel is curently working properly?
Not the most qualified person for this troubleshooting by far, merley trying to understand what may cause the problem... while more helpful people step in 🙂
My FQP-Version of the ACA mini. Same enclosure as usual, but less high. And I made a linear power supply to stack with the amp. First, I used a conventional 50VA Hamilton transformer, but it was mechanically buzzing :-(
Now, I have a 50VA from Toroidy from Poland. Calm.
The power regulator is a chinese so called "Studer 900" board.
Here I show my kitchen setup, preamp with a 6x24 crossover (yes yes, I must change the white power-LED to an orange one).
Now, I have a 50VA from Toroidy from Poland. Calm.
The power regulator is a chinese so called "Studer 900" board.
Here I show my kitchen setup, preamp with a 6x24 crossover (yes yes, I must change the white power-LED to an orange one).
Studer powers ACA Mini. Interesting! It copes with the load obviously. How does it compare to your other build ?
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Smile, I was a Studer employee from 2007 to 2009...
I will compare it later to my other build(s) and try to comment here.
No, I think it is loaded on its limits, but it seems to be OK. The heatsink does not get hot as the ACA mini heatsinks 😎
I think, a good quality torroid trafo will handle it. Possibly it is wise to load the caps first and then switch on the bias of the ACA mini, same as with the small smps from the completion kit.
But in fact, it started up flawless. I think for the short period it will stem the inrush current.
But this tranny here was not a success, it was buzzing!
But in fact, it started up flawless. I think for the short period it will stem the inrush current.
But this tranny here was not a success, it was buzzing!
Hmm, this are some NOS enclosure kits. I have them from this shop: https://shop.lasatec.ch/
Be warned: the online shop is awful, you dont find anything. And I dont know, if they can handle international orders. I always order per mail info@lasatec.ch and I collect the parts personally, as it is not far from my home.
For the "high" enclosure you need:
| Bestell-Nr. | Bezeichnung | Anzahl | Einzelpreis | Preis |
| 9622.1612 | Frontplatte Alu Eloxiert 167 x 127 mm | 2 | CHF 19,00 | CHF 38,00 |
| 9631.16 | Profilstab Aluminium 160 mm | 4 | CHF 2,80 | CHF 11,20 |
| 9606.1616 | Lochblech, Stahlblech schwarz 160 x 160 mm | 2 | CHF 11,10 | CHF 22,20 |
| 9606.1612 | Lochblech, Stahlblech schwarz 160 x 120 mm | 2 | CHF 6,10 | CHF 12,20 |
| 690.2 | Blechschraube 2.9 x 9.5 mm | 8 | CHF 0,06 | CHF 0,48 |
| Total | CHF 84,08 |
For the middle flat enclosure
| Bestell-Nr. | Bezeichnung | Anzahl | Einzelpreis | Preis |
| 9622.1608 | Frontplatte Alu Eloxiert 167 x 87 mm | 2 | CHF 11,22 | CHF 22,44 |
| 9631.16 | Profilstab Aluminium 160 mm | 4 | CHF 2,80 | CHF 11,20 |
| 9606.1616 | Lochblech, Stahlblech schwarz 160 x 160 mm | 2 | CHF 11,10 | CHF 22,20 |
| 9601.1608 | Stahlblech schwarz 160 x 80 mm | 2 | CHF 2,15 | CHF 4,30 |
| 690.2 | Blechschraube 2.9 x 9.5 mm | 8 | CHF 0,06 | CHF 0,48 |
| Total | CHF 60,62 |
and the very flat I used for the PSU (not enough space for an ACA mini!
| Bestell-Nr. | Bezeichnung | Anzahl | Einzelpreis | Preis |
| 9622.1606 | Frontplatte Alu Eloxiert 167 x 67 mm | 2 | CHF 6,00 | CHF 12,00 |
| 9631.16 | Profilstab Aluminium 160 mm | 4 | CHF 2,80 | CHF 11,20 |
| 9606.1616 | Lochblech, Stahlblech schwarz 160 x 160 mm | 2 | CHF 11,10 | CHF 22,20 |
| 9601.1606 | Stahlblech schwarz 160 x 60 mm | 2 | CHF 1,85 | CHF 3,70 |
| 690.2 | Blechschraube 2.9 x 9.5 mm | 10 | CHF 0,06 | CHF 0,60 |
| Total | CHF 49,70 |
Add 7.7% tax. And the shipping out of Switzerland will be very expensive, I guess.
The parts are on stock for many years. The protection film on it is shrinked and I always need some aceton or similar to clean the parts and to open the holes of the back top and bottom plates.
I just switched on the amp while the switch for bias of the ACA mini is in "On" position: the Studer PSU does very nice and slow increase the voltage, some startup ramp (I dont find the correct words in english).
Perfect!
Perfect!
@Nelson Pass
Dear Papa, I wish you to produce new "PassDIY" stickers and hand them over to the store! Is this possible, please?
... it does not hurry
Dear Papa, I wish you to produce new "PassDIY" stickers and hand them over to the store! Is this possible, please?
... it does not hurry
This is the power supply circuit I used
https://www.ebay.com/itm/195518741063
and this is the fine 50VA toroidal from Poland
https://sklep.toroidy.pl/en_US/p/TTSA0050-Transformer-AUDIO-TSA50VA-voltage-to-50V/309
select single secondary 20V and "filled epoxy resin" in the center
https://www.ebay.com/itm/195518741063
and this is the fine 50VA toroidal from Poland
https://sklep.toroidy.pl/en_US/p/TTSA0050-Transformer-AUDIO-TSA50VA-voltage-to-50V/309
select single secondary 20V and "filled epoxy resin" in the center
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A comment for all the first time amp builders / electronic newcomers:
The powersupply Nelson is recommending is safe! The difference to a linear supply is very subtle! Be aware: a linear power supply is dealing with lethal voltages and has to be built in regards of some security aspects!
Better stick with the fine meanwell switching powersupply!
The powersupply Nelson is recommending is safe! The difference to a linear supply is very subtle! Be aware: a linear power supply is dealing with lethal voltages and has to be built in regards of some security aspects!
Better stick with the fine meanwell switching powersupply!
Thank you, Nelson - and DIYaudiostore - and everybody involved!
Building the Mini was BIG fun and you all have made it pretty easy for a beginner.
Seeing what 2x5 TrueWatts (tm) can actually do is quite an experience.
Building the Mini was BIG fun and you all have made it pretty easy for a beginner.
Seeing what 2x5 TrueWatts (tm) can actually do is quite an experience.
