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I would have to say it's the amp. I've listened to a bunch of different amps on these same speakers in the same room and have noticed this. These are highly efficient speakers (102 - 105db, manufacturers specs seem to vary). I haven't noticed this on my test speakers that are lower efficiency, but the volume is turned higher on them to get the same low output.
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I did that off the of my head. Yes FX8 also.I'm sure if I did through my pile I would find others that I forgot as well. Soundcraftmen 800 comes to mind now too. The point is, you will find far more commercial amps that use lateral MOSFET than you will ever find with vertical. Verticals are less expensive so why do you suppose laterals were so much more common? For their sound and durability.
Despite incorrect VAS current - as I await the 1k pots to come in, I have been listening to this amp in mono. Sounds very nice - probably best word to say is it is very neutral. Doesn't add or take anything to the music. Running about 175mA bias - perhaps more would sound even better? Jazz trios are very very nice.
One other alternative is to cut the trace to the pot and solder a small 500R SMT resistor in series to get the adjustment range I need?
Edit: I think the current feedback topology makes the latFETs sound better for bass. I do not sense lack of it with the test tracks so far. But an AB test with a vertical hexFET is the best way to tell - so will do that when I am up in stereo. So far very pleased though.
One more thing, the Aliexpress latFETs are holding their own - I do believe these are genuine Hitachi's pulled from an old amp somewhere. They sound nice and are taking the heat well.
Lucked out again as I paid $5.50/pair...
One other alternative is to cut the trace to the pot and solder a small 500R SMT resistor in series to get the adjustment range I need?
Edit: I think the current feedback topology makes the latFETs sound better for bass. I do not sense lack of it with the test tracks so far. But an AB test with a vertical hexFET is the best way to tell - so will do that when I am up in stereo. So far very pleased though.
One more thing, the Aliexpress latFETs are holding their own - I do believe these are genuine Hitachi's pulled from an old amp somewhere. They sound nice and are taking the heat well.
Lucked out again as I paid $5.50/pair...
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My bag of 50 1k trimpots came in today so I replaced all the CCS pots. VAS current is now properly set at 160mV across the 10R resistor. Overall quiescent current is 160mA. Zero offset is about 1mV.
The amp sounds very nice, distortion is low - perhaps lower than FX8. Measurements of the speaker show speaker distortion only. Bass is not lacking, very articulate and well controlled.
Something is not right though because this amp seems to be too cool for a 160mA bias current. The heatsink is barely warm. I know my FX8 at the same bias is quite warm with same heatsink. So I am not sure what is different given that I am measuring 1.60v drop across the 10R x 10w safety resistor on the power rail.
The amp sounds very nice, distortion is low - perhaps lower than FX8. Measurements of the speaker show speaker distortion only. Bass is not lacking, very articulate and well controlled.
Something is not right though because this amp seems to be too cool for a 160mA bias current. The heatsink is barely warm. I know my FX8 at the same bias is quite warm with same heatsink. So I am not sure what is different given that I am measuring 1.60v drop across the 10R x 10w safety resistor on the power rail.
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Well that's reassuring to hear. It's almost cool enough to mount two amps on one heatsink without a fan.
Thanks for the nice amp design and layout - sounds very good so far.
VSSA comparing (possible?) to FX8
Hallo X.
I like the FX8 too but different reason.
First i have WAKE UP ! the LatMos- also the Aliexpress ones with little
2 Ampere and nothing blowing up, that could be good LatMos- old Stock Parts- where ever the little clever Chinese picked them up !
I have compared it with Tech DIY bought- and the plastic case looks equally.
After fixing my bad idea to use different Input LTP without 180° rotation pinout the Amp is well biased and fine working.
After 2 Weeks in use i registered a bit better sorted image and opens a bit more in wide.
The Rest is a very clear detailed, not fatiguing presentation you can light follow.
On my VSSA i have find out that the Capacitor "Antenna" style is the most
reason for hum here- thanks to jwilhelm!
I continuous work on it to fit it on more size esthetic heat sink.
i agree.
Here my Chinese LatMos.
Bangla
Hallo X.
What did you mean is it possible to comparing?
I like the FX8 too but different reason.
First i have WAKE UP ! the LatMos- also the Aliexpress ones with little
2 Ampere and nothing blowing up, that could be good LatMos- old Stock Parts- where ever the little clever Chinese picked them up !
I have compared it with Tech DIY bought- and the plastic case looks equally.
After fixing my bad idea to use different Input LTP without 180° rotation pinout the Amp is well biased and fine working.
After 2 Weeks in use i registered a bit better sorted image and opens a bit more in wide.
The Rest is a very clear detailed, not fatiguing presentation you can light follow.
On my VSSA i have find out that the Capacitor "Antenna" style is the most
reason for hum here- thanks to jwilhelm!
I continuous work on it to fit it on more size esthetic heat sink.
Yes
i agree.Here my Chinese LatMos.
BanglaAttachments
One of the J160's looks like it has been sanded. All have been desoldered. Suspicious parts make better amps ?
My first set from Aliexpress were clean and pristine like new Renesas. The second set look like used Hitachi's pulled from somewhere. Both work and sound good though.
Hallo.
Yes we all are a bit in twice about that parts.
In moment i have nothing negative to say, but for better trust the next i will buy from
our German distributor Reichelt- meanman gives me the advise to do so. For better
sleeping.
still4given i also was looking to Tayda- not much in Sortiment but good i could see.
On other hand xrk is like a dog who's sniffing low or budget priced parts...he...he...!
Cheers Bangla
Yes we all are a bit in twice about that parts.
In moment i have nothing negative to say, but for better trust the next i will buy from
our German distributor Reichelt- meanman gives me the advise to do so. For better
sleeping.
still4given i also was looking to Tayda- not much in Sortiment but good i could see.
On other hand xrk is like a dog who's sniffing low or budget priced parts...he...he...!
Cheers Bangla
In stereo
I replaced the 470uF caps (all I had on hand earlier) with some Sanyo 1000uF 50v caps, and mounted both boards on one heatsink (fan assisted). Now playing in stereo. Very nice
Closeup:
Testing natural convention (no fan) in vertical orientation:
At moderate volumes, the vertical fan-free mode is not too hot. This is a pretty cool running amp.
I replaced the 470uF caps (all I had on hand earlier) with some Sanyo 1000uF 50v caps, and mounted both boards on one heatsink (fan assisted). Now playing in stereo. Very nice
Closeup:
Testing natural convention (no fan) in vertical orientation:
At moderate volumes, the vertical fan-free mode is not too hot. This is a pretty cool running amp.
Attachments
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The 2200uF are part of the feedback network. I have never been a big believer in the sound of the components themselves as some of my most satisfying builds were 'junk box specials' made from either recycled parts or old crap I've had since forever that is of questionable pedigree.
Use in that position whatever you feel happy with.
Use in that position whatever you feel happy with.
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