It’s getting OT, but the measurements were made with 20vpp into a 7kohm load (for a preamp output).
Here is carbon film 6k8 feedback resistor:
Here is same preamp and measurement but with 6k8 metal oxide thick film:
This was discussed in the Aksa Lender preamp thread a while back.
Here is carbon film 6k8 feedback resistor:
Here is same preamp and measurement but with 6k8 metal oxide thick film:
This was discussed in the Aksa Lender preamp thread a while back.
I voted for AX16 but only because AX14 wasn't a choice. I've built AX14 prasi boards, made from his gerber files by pcbway.com. Sound is excellent, circuit is stable, and boards are inexpensive. The other amps are probably also excellent but I can't imagine not being satisfied with the AX14. I guess it comes down to your preference between FET or BJT output transistors and availability of parts.
The FH9HVX with single pair of FQA MOSFETs achieves better performance than FH11 with two pairs of IRFP240/9240. So not needed if you go FH9HVX. The use of KSC1845 in the LTP and KSA1381 / KSC3503 drivers also helps to improve performance of FH9HVX variant. No matching is necessary and the FQA’s ha e higher gm too for better bass authority.
Explain better performance? Do you mean on 8-ohms, because it seems unlikely if you are running 4-ohms.
I have read somewhere in the 100w apex thread that FH11 is a FH9 with 2 added transistors. Can i use a FH11 board as a FH9 or vice versa?
Yes, they are basically the same amp but modifications made for the transistors to handle higher voltages. The FH9 had BC546 for the front end LTP and that cannot handle the higher voltages of the FH11. You could use the same board if you twisted the legs and used say KSC1845 or 2N5551. On the drivers, you need to use either KSA1381 and KSC3503 and not BD140/139. I think the legs on those might be the same. Finally, for the output stage, you could just add extra drivers in parallel with their own source resistors. Definitely, an FH11 could be populated with only 1 set of outputs for an FH9.
Here are the schematics that I made 4 years ago for FH11:
vs the FH9:
But since then, I have the FH9HVX which has some improvements to the layout quality and choice of components:
Here are the schematics that I made 4 years ago for FH11:
vs the FH9:
But since then, I have the FH9HVX which has some improvements to the layout quality and choice of components:
I can send an alternate silkscreen, that shows you which parts to populate for the FH9 on the same board gerbers I sent you for the FH11. The parts notated for the board and schematic I sent you is HV, they set up the front end to handle ~80-90Vdc. But if you plan to use same size board, why not spend the extra $10, populate it as a FH11 and you will have a much more stable amp across lower loads at the same voltage? IMO
place please all components as close as possible to pcb-except 1 2 3... 5W resistors. not only visually,but technicaly best way to do it. you are so close to it! 🙂
I'm planning to build the apex FH11. Can anyone recommend a PSU and Speaker protector for the FH11 and provide the gerber files required? As i am looking to order from JLCPCB or PCBWay. Thanks!
I usually just order a board from eBay, then I can ensure the parts are legit and build to my design.
Here is a simple CRC PSU from Prasi - very compact and will be plenty of capacitance for your build.
You don't say what kind of Xfrmr - be sure you have a dual secondary for this board.
Schematic, Picture and gerbers attached.
- I have not built or tested this, so the greater group will have to tell you if they see any problems with the board as is.
Here is a simple CRC PSU from Prasi - very compact and will be plenty of capacitance for your build.
You don't say what kind of Xfrmr - be sure you have a dual secondary for this board.
Schematic, Picture and gerbers attached.
- I have not built or tested this, so the greater group will have to tell you if they see any problems with the board as is.
Attachments
CRC is Capacitor, Resistor, Capacitor , but I’m not qualified to give you pros and cons. You could also have all Capacitors or Capacitor, Inductor, Capacitor and could even have multiple stages with a combination CRCLC, may be an endless combination - IDK. Again I am not qualified to give you benefits one over another.
Thanks xrk 🙂
Open and crisp sound, punch bass, lot off scene... 🙂
But:
it has "Sss", siblings, (song Childrens off Sanchez...), it burns both resistors 4,7 Ohms/2W when starts, later normally working, (possible ground loop off inputs wires thru Apex preamp)... PSU electrolyt bank is 2 pc0,22uF MKP, plus 4 pc 1uF MKT, plus 4 pc 470uF plus 20 pc 1000uF total... +-47V, 130mA output current across output transistors no load... 4,7pF is made from 2 serial connected 10pF MLCC NP0...
Similar expirience? Sugestions?
Open and crisp sound, punch bass, lot off scene... 🙂
But:
it has "Sss", siblings, (song Childrens off Sanchez...), it burns both resistors 4,7 Ohms/2W when starts, later normally working, (possible ground loop off inputs wires thru Apex preamp)... PSU electrolyt bank is 2 pc0,22uF MKP, plus 4 pc 1uF MKT, plus 4 pc 470uF plus 20 pc 1000uF total... +-47V, 130mA output current across output transistors no load... 4,7pF is made from 2 serial connected 10pF MLCC NP0...
Similar expirience? Sugestions?