no need to suspect fake IRFP , but dunno for 2SK170BL
it depends was that purchase from reputable member of one-offer
you can test them out of pcb , simple Idss test - with and without some source resistor (say 20-33 ohms) , and calculate xconductance from that
if that is comparable with Toshiba data , then good - search for culprit somewhere else
anyway - same situation with both channels ?
pics possible ?
it depends was that purchase from reputable member of one-offer
you can test them out of pcb , simple Idss test - with and without some source resistor (say 20-33 ohms) , and calculate xconductance from that
if that is comparable with Toshiba data , then good - search for culprit somewhere else
anyway - same situation with both channels ?
pics possible ?
The ACA has a low damping factor so any impedance hills and valleys of the load show up as frequency response deviations. It performs best with single driver full range speakers although the high end may be a little strong. Many two or three way crossovers do not have a flat impedance characteristic.
Ok, I did some changes to the power supply.
I've replaced the toroid with a 20VAC 50VA and regulated with LT3083.
The amp draws about 1.1A now. I've kept the bias to be 10 VDC
The frequency response has improved a lot more. I've tested with an 8 ohm load.
Don't have a full graph but from some quick measurements the is a slight dip from about 1k to 3k at about 1 db down but flat till about 15kHz then gain goes up high even into the 200kHz range.
It does sounds alot better. I find that bass is a bit on the light side, but that could be the damping factor or my regulator. I havent measured my jfets yet.
I would say that it is working, i'll apply the mod and see if it improves things.
Thanks for the inputs.
Leo
I've replaced the toroid with a 20VAC 50VA and regulated with LT3083.
The amp draws about 1.1A now. I've kept the bias to be 10 VDC
The frequency response has improved a lot more. I've tested with an 8 ohm load.
Don't have a full graph but from some quick measurements the is a slight dip from about 1k to 3k at about 1 db down but flat till about 15kHz then gain goes up high even into the 200kHz range.
It does sounds alot better. I find that bass is a bit on the light side, but that could be the damping factor or my regulator. I havent measured my jfets yet.
I would say that it is working, i'll apply the mod and see if it improves things.
Thanks for the inputs.
Leo
@all212: the film-cap across the 3.300µF that I have soldered, is meaning only a very small improvement in sound.
If you want to listen to an ACA "at its best": give it a 24-25VDC PSU.
For example the one shown below.
You only need a dual 18VAC secondary - transformer (rated at 120-160VA) to connect to the ACAs.
At what voltage are you operating your ACAs?
Best regards - Rudi
If you want to listen to an ACA "at its best": give it a 24-25VDC PSU.
For example the one shown below.
You only need a dual 18VAC secondary - transformer (rated at 120-160VA) to connect to the ACAs.
At what voltage are you operating your ACAs?
Best regards - Rudi
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What about a 24v smps LED supply brick?
Like this one, good for 5 amps?
http://www.amazon.com/gp/product/B00LUIKY4S
Does a 24v supply give it a theoretical max 8w capability vs 5w for 19v?
Like this one, good for 5 amps?
http://www.amazon.com/gp/product/B00LUIKY4S
Does a 24v supply give it a theoretical max 8w capability vs 5w for 19v?
We use power bricks in the kit, and they are surprisingly un-noisy. Is that "Papa Pass" magic? Possibly, but he does have an Audio Precision tester so he can actually measure this stuff 
My biggest concern about the bricks you linked to is there seem to be a lot of complaints about them in the reviews..
My biggest concern about the bricks you linked to is there seem to be a lot of complaints about them in the reviews..
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We use power bricks in the kit, and they are surprisingly un-noisy. Is that "Papa Pass" magic? Probably, but he does have an Audio Precision tester so he can actually measure this stuff
My biggest concern about the bricks you linked to is there seem to be a lot of complaints about them in the reviews..
I have four of these and have not had a problem with them not working. I did measure the AC ripple as 16mV - is that bad? I do have a Dell SMPS on one of my class D amps and it is very quiet but have not actually measured ripple on that one.
The ACA doesn't require matched 2SK170's as each monoblock only uses 1. Is it OK to use cheap 2SK170BL ones from China? 40 in a bag for $7.
Original free shipping 2SK170BL 2SK170 K170 TO92 40PCS/LOT in Stock-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group
I know, a crapshoot... I actually have two real ones I bought from Linear Systems but that order for two with shipping cost the same as 40 from China!
Original free shipping 2SK170BL 2SK170 K170 TO92 40PCS/LOT in Stock-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group
I know, a crapshoot... I actually have two real ones I bought from Linear Systems but that order for two with shipping cost the same as 40 from China!