If you expand the picture, it says AS-2XXX, so likely 200VA each. In fact, a few posts above (post 1227), he states they are Antek AS-2238. 200VA and 38V secondaries.
Best,
Anand.
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@bloqhed
Your build and layout is looking great.
It’s been a while since I built this. I’ll let someone with more recent experience say which way (CW or CCW) to set the pot for initial turn on.
Bulb tester or variac is a good way to go. Can also use a 10W 10ohm resistor in series with each PSU rail leading into amp. Measure voltage drop across this at turn on and if it’s more than a few volts, shut down quickly and investigate. Also monitor DC offset at output and if that is way off (more than a couple volts, something is wrong).
Good luck!
Your build and layout is looking great.
It’s been a while since I built this. I’ll let someone with more recent experience say which way (CW or CCW) to set the pot for initial turn on.
Bulb tester or variac is a good way to go. Can also use a 10W 10ohm resistor in series with each PSU rail leading into amp. Measure voltage drop across this at turn on and if it’s more than a few volts, shut down quickly and investigate. Also monitor DC offset at output and if that is way off (more than a couple volts, something is wrong).
Good luck!
Thank You, XRK, for designing this amp.
I'm currently building a prototype based on it.
Problem is, I cant find locally the 220uF bi-polar Nichicon Muse in the NFB circuit (C106).
Available is polarized Nichikon KZ Muse. May I use it instead, and if it's possible which direction should I connect? Positive or negative to ground?
Checked the drawing of the FX-8 from Apex, there the negative pin is to gnd, but I prefer to ask for confirmation.
Kind Regards
Stanislav
I'm currently building a prototype based on it.
Problem is, I cant find locally the 220uF bi-polar Nichicon Muse in the NFB circuit (C106).
Available is polarized Nichikon KZ Muse. May I use it instead, and if it's possible which direction should I connect? Positive or negative to ground?
Checked the drawing of the FX-8 from Apex, there the negative pin is to gnd, but I prefer to ask for confirmation.
Kind Regards
Stanislav
Stanislav,
Looking at the schematic on post #1 of this thread, if using a polarized capacitor for C106, it appears that the positive lead [anode] of the C106 capacitor should connect to R108 (680 ohm resistor) and the negative lead [cathode] should connect to R109 (10 ohm resistor).
Best,
Anand.
Looking at the schematic on post #1 of this thread, if using a polarized capacitor for C106, it appears that the positive lead [anode] of the C106 capacitor should connect to R108 (680 ohm resistor) and the negative lead [cathode] should connect to R109 (10 ohm resistor).
Best,
Anand.
I think a non-polar is functionally advisable here, and preferable to back-to-back ones (for convenience of mounting on the board). While the Nichicon Muse NO listed in the BOM is probably the best choice, I think another NP is preferable over the other alternatives.
Where are you locate? In the US Mouser has plenty of 220uF, 16V ’lytics of other manufacturers in stock. I did not even check other suppliers.
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Thanks for all your advice. I'm located in Bulgaria. High quality caps are exotic here. Those Nichicon KZ Muse I found on a local listing (not a retailer), the guy is selling capacitors for recap, but he hasn't unipolar 220uf. He has 100uf unipolar though... I can use two in parallel. I just wish I could avoid paralleling/series those capacitors from aesthetical point of view. But if you guys think there will be a performance/sound quality degradation due to the use of polarized capacitor, I'll have to swallow my OCD and use two caps to achieve the desired value.
Understood. Probably will use 2x100uf in parallel temporary, until I find the proper value.
Last question (I hope) - the NFB resistors are annotated as carbon film showing higher 2nd order harmonic compared to metal film with higher 3rd harmonic on the FFT graph. In the Mouser BOM these are metal-film. What's the final design?
Last question (I hope) - the NFB resistors are annotated as carbon film showing higher 2nd order harmonic compared to metal film with higher 3rd harmonic on the FFT graph. In the Mouser BOM these are metal-film. What's the final design?
Hi Forum Members,
I have pretty much finished populating my FH9HVX boards, All Cees boards, and SFP soft start board. I will be working to clean them up a bit as I used liberal amounts of Flux. Then comes testing.
My questions for those of you who have used X's little blue MOSFET helper boards relates to snubber components. I reviewed posts #1143 and #1144 for reference. If I understand correctly R131 and R132 remain on the main amplifier board, and the spot for a through-hole resistor on the helper board remains empty. Is this correct? Also, what components (if any) get installed on the helper boards? Thank you in advance.
Respectfully, Dave M.
(Just for clarification I am referring to the small square helper boards, not the larger tombstone-shaped ones)
I have pretty much finished populating my FH9HVX boards, All Cees boards, and SFP soft start board. I will be working to clean them up a bit as I used liberal amounts of Flux. Then comes testing.
My questions for those of you who have used X's little blue MOSFET helper boards relates to snubber components. I reviewed posts #1143 and #1144 for reference. If I understand correctly R131 and R132 remain on the main amplifier board, and the spot for a through-hole resistor on the helper board remains empty. Is this correct? Also, what components (if any) get installed on the helper boards? Thank you in advance.
Respectfully, Dave M.
(Just for clarification I am referring to the small square helper boards, not the larger tombstone-shaped ones)
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Hi X.
I settled on 23mv/105ma bias and 60v rail, heatsinks sitting at 38'c idle and about 40 playing at low levels. Mind you this is with 28'c ambient, so I'm happy with that. I'll run it a while like this then maybe try 26mv...
The labels are laser printed water slide decals, like those you get with airfix models, I can't remember where I got them but it is just an A4 sheet and I drew them up in Inkscape and printed, cutout with scalpel, soak in water and slide into place, dab dry carefully with q-tip...
X, thanks again for all your efforts in designing this amp and the speakers too, it is really a fantastic combo and I am thoroughly chuffed with my setup now, don't think there is anything I would change.
Maybe a set of bookshelves for the home office. I do have a few spare gainclone amps now.
Cheers.
Nik.
I settled on 23mv/105ma bias and 60v rail, heatsinks sitting at 38'c idle and about 40 playing at low levels. Mind you this is with 28'c ambient, so I'm happy with that. I'll run it a while like this then maybe try 26mv...
The labels are laser printed water slide decals, like those you get with airfix models, I can't remember where I got them but it is just an A4 sheet and I drew them up in Inkscape and printed, cutout with scalpel, soak in water and slide into place, dab dry carefully with q-tip...
X, thanks again for all your efforts in designing this amp and the speakers too, it is really a fantastic combo and I am thoroughly chuffed with my setup now, don't think there is anything I would change.
Maybe a set of bookshelves for the home office. I do have a few spare gainclone amps now.
Cheers.
Nik.
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