Virtual Audition of Very Simple Quasi MOSFET Amp

[xrk971]

Don't get me wrong. The TPA311xD2 amp is excellent for a lot of things. But good discrete class AB amps by great designers on this forum are a whole level above them. Getting past the 35v dual rail PSU is a big hurdle though. You can't just use a 19v laptop brick - which is a super convenience.

FH9 is great choice. Might as well make it FH9HV (use KSC3503 and KSA1381 drivers vs BD's and higher voltage rating caps). Run it at 53v rails and dynamics are superb.

 

[Bangla H]

Ypaudio
My proposal is look first to FX8, it is one stage simpler- no driver and tempco needed
and runs very well since near 4 month daily here.
Board is tiny too 50x50mm.

Cheers

 

[xrk971]

FH9 is basically FX8 with vertical MOSFETs. There's not an extra stage - just BD139 temperature compensator. The HD that Inmeasured on FH9 is significantly less than my 50mm FX8. Construction wise - the FH9 is maybe 4 components more.

 

[prasi]

Unfortunately I just bought several type of tpa3116 board
I have no other amp to compare.
Hmm.. I will prepare to build discrete amp in near future. I think I will go with FH9 first. Thanks Xrk971

Go with FX-8, its simplest and very good sounding. If you are ambitious enough, my suggestion would be FX-8 Bimo mod, the most Hi-Fi sounding amp audio clip that I heard in this thread. if you build it as per recommendation of the designer (component type and quality), i am sure it would satisfy your hi-fi requirements.
reg
Prasi

 

[xrk971]

The FH9 and CFH7 are the easiest to build in my opinion, FX8 Bimo is also excellent sounding but a more complicated build. I prefer sound of hexFET over lateral FET. My feeling is that the bass of hexFET has more impact. The outputs are significantly less expensive too. Although many claim lateral FETs to be more hifi sounding - but not sure why.

 

[thiagomogi]

"My feeling is that the bass of hexFET has more impact"


you can measure it?

Thiago

 

[boyet0173]

Hi Thiago/Sonal/Prasi,

FX8-Borys mod is best sounding too. Can you make it for pcb layout?
Thanks in advance.

Regards,
Boyet

 

[ypaudio]

Hi Thiago/Sonal/Prasi,

FX8-Borys mod is best sounding too. Can you make it for pcb layout?
Thanks in advance.

Regards,
Boyet

for Q4 and Q5 , I only can see 2SK and 2SJ. what is the suitable for Q4 and Q5
could you help me to show the link? I found this link http://www.diyaudio.com/forums/solid-state/292226-directory-apex-audio-amplifiers.html
and still searching which one is most easier to build.

I think FH9 first, because I have several IRFP240 & IRFP9240

 

[boyet0173]

Hi ypaudio,

2SK1058 or ALF08N16V and 2SJ162 or ALF08P16V.

"I think FH9 first, because I have several IRFP240 & IRFP9240" - Please try and update the result.

 

[xrk971]

"My feeling is that the bass of hexFET has more impact"


you can measure it?

Thiago

It shows up as maybe (but not always visible in frequency response) +0.5dB boost over 40Hz to 100Hz range - but the effect is really more of a transient effect of higher slew rate or attack. Listen to sound clips from post 3 and 4 and hear for your self. Recorded under same condition with only difference being amps.

 

[Bangla H]

FH9 is basically FX8 with vertical MOSFETs. There's not an extra stage - just BD139 temperature compensator

Uuups: some temporary senior moments.......sorry.

The Borys mod looks interesting too. Missed it in Apex thread- any explanation what is
changing in sound profile or anything with extra MPSA?

 

[camelator]

Go with FX-8, its simplest and very good sounding. If you are ambitious enough, my suggestion would be FX-8 Bimo mod, the most Hi-Fi sounding amp audio clip that I heard in this thread. if you build it as per recommendation of the designer (component type and quality), i am sure it would satisfy your hi-fi requirements.
reg
Prasi

Agree...
I also have a TPA3116
Since I built my FX8, TPA3116 is sleeping.
FX8 provides better dynamics. It is night and day.

 

[apexaudio]

Hi Thiago/Sonal/Prasi,

FX8-Borys mod is best sounding too. Can you make it for pcb layout?
Thanks in advance.

Regards,
Boyet

This schematic is wrong, 1N4148 must be connected like in this schematic.
Regards

 

[boyet0173]

Hi Apex,

When I removed the 1N4148 the sound got distorted as per your recommendation.

Regards,

 

[apexaudio]

Hi Apex,

When I removed the 1N4148 the sound got distorted as per your recommendation.

Regards,

Can you measure voltages on 680R resistors?

 

[xrk971]

CFH9 Amp

I just finished building and testing the CFH9 amp. I fitted it with Juma's cap multiplier and running off 300VA toroidal trafo with 39v rails after the cap multiplier. Operating at 460mA overall quiescent bias.

http://www.diyaudio.com/forums/solid-state/294834-cfh7-amp-46.html

This amp has pretty clean square waves too:

Here are sound clips of the 3 reference tracks. Also included is a new clip of Nils Lofgren's Keith Don't Go. You can really hear the articulation of the guitar here. Change extension to .mp3 to listen.

Nice sounding amp.

Frequency response and measured HD at speaker is very low:

 

[xrk971]

X's 2016 SS Year in Review

All this started just last March and has been a blast learning from all of the experts here. A big thanks to Prasi, Sonal Kunal, Idefixes, Dacz, Kees52, and Jkeutermann for providing me with such great Gerbers that made this possible. Also, a huge thanks to the great designers of the circuits that I built with Apex Audio and Nelson Pass as probably the leading sources of inspiration that got me to start building amps.

Not shown below are CFH9 (currently in the hot seat), VHEX+ (in a case), F5HA with IRF610/9610 (in case), and ACA deadbug (at office). My journey was (as best as I can remember) as follows: Dx, ACA P2P, Inv JFET Circlophone BJT OPS, DOS TDA7297 w shunt reg, FX8 50mm - Sonal layout, FX8 Bimo - Prasi layout, VHEX+, FH9, FH9HV, VSSA JK thru-hole, Inv JFET Circlophone MOSFET OPS, Ranchu/Aksa Quasi - Prasi layout, Apex AX11 - Prasi layout, M2 - Teabag layout, Kees52 allFET Circlotron, CFH7 - Idefixes layout, Ranchu/Aksa Quasi - Dacz layout, Juma F5 2SK2013/2SJ313 - P2P, F5HA - P2P, CFH9 - Idefixes layout, F5HA - Prasi layout, F5HA 2SK2013/2SJ313 w Juma shunt reg - Prasi layout.

 

[prasi]

All this started just last March and has been a blast learning from all of the experts here. A big thanks to Prasi, Sonal Kunal, Idefixes, Dacz, Kees52, and Jkeutermann for providing me with such great Gerbers that made this possible.

Not shown below are CFH9 (currently in the hot seat), VHEX+ (in a case), F5HA with IRF610/9610 (in case), and ACA deadbug (at office). My journey was (as best as I can remember) as follows: Dx, ACA P2P, Inv JFET Circlophone BJT OPS, DOS TDA7297 w shunt reg, FX8 50mm - Sonal layout, FX8 Bimo - Prasi layout, VHEX+, FH9, FH9HV, VSSA JK thru-hole, Inv JFET Circlophone MOSFET OPS, Ranchu/Aksa Quasi - Prasi layout, Apex AX11 - Prasi layout, M2 - Teabag layout, Kees52 allFET Circlotron, CFH7 - Idefixes layout, Ranchu/Aksa Quasi - Dacz layout, Juma F5 2SK2013/2SJ313 - P2P, F5HA - P2P, CFH9 - Idefixes layout, F5HA - Prasi layout, F5HA 2SK2013/2SJ313 w Juma shunt reg - Prasi layout.

Such a nice collection of amps!. I am glad to be helpful.
reg
Prasi

 

[Idefixes]

Such a nice collection of amps!. I am glad to be helpful.
reg
Prasi

I too....

Marc

 

[Bangla H]

A good Season for you in Hunting SS Amplifier

Hi X,
my first though if i see this Collection.
Good Resumee for end of a good Season.
Don't let stumble Terry to see your Collection.

Cheers.