Aksa Lender P-MOS Hybrid Aleph (ALPHA) Amplifier

[Juntuin]

With that in mind are there advantages of say using 28V rails and using FDA38N30 and FQA36P15 instead of IRFP240 /9240. I believe Hugh suggested those output devices at the start of this thread.
I am about to begin ordering parts so if anyone has any comments regarding this I would be grateful.
Regards

I guess going with Hugh's recommendation wont hurt.

I took 36P15P and 36N30P, but they are IXYS-products (IXTQ). Don't know are IXYS any good though have some matched IRFP's also from previous projects.

 

[pcgab]

I'm considering other heatsink options, and am trying to figure out how to calculate how many watts dissipation this heatsink can perform:

http://www.heatsinkusa.com/10-080-wide-extruded-aluminum-heatsink/

That profile, @6" height would be able to dissipate?

Is there an easy formula to use, they provide c/w/3" of 0.80.

 

[alibear]

Can get FDA and FQA from On semi.
Regards

 

[xrk971]

I think that rating means it has a 0.8 deg C rise for every watt for a 3in length of the heatsink. So for 90w that’s 72 C rise above ambient. Usual practice is 55C max and if ambient is say 25C you can take 30C rise. 72C/30C = 2.4. So 2.4 x 3in = 7.2in so 7in to 8in length of heatsink should do it. 6in is good for maybe 75W.

 

[AKSA]

No problem at all with Fairchild and IXYS mosfets. I have used them for years. In fact I use the IXYS devices rated at 1040W on my Maya amplifiers and can recommend all of them.

Heatsinks are problematic for any Class A. You should plan for no more than 55C operational with 30C ambient. That gives you 25C rise above ambient. Be aware that adding 11C to any electronic device reduces MTBF by 50% (Arrhenius Equation) and 55C is just acceptable for touching for one minute. 65C is only 10 seconds.

Hugh

 

[pcgab]

I think that rating means it has a 0.8 deg C rise for every watt for a 3in length of the heatsink. So for 90w that’s 72 C rise above ambient. Usual practice is 55C max and if ambient is say 25C you can take 30C rise. 72C/30C = 2.4. So 2.4 x 3in = 7.2in so 7in to 8in length of heatsink should do it. 6in is good for maybe 75W.

So two 6" sections of that heatsink would be enough for a 20w stereo pair?

I may try that route.

 

[xrk971]

So two 6" sections of that heatsink would be enough for a 20w stereo pair?

I may try that route.

Yes, just stay below 1.5amps bias for +/-24v though, of splurge and get 7in for the full 1.8amps.

 

[pcgab]

Yes, just stay below 1.5amps bias for +/-24v though, of splurge and get 7in for the full 1.8amps.

Will do. I'm going to use the dell heatsinks to test the circuit, so I can listen sooner

If I try the other route, I'll likely get 8" or more, still playing with some ideas.

 

[needtubes]

I took 36P15P and 36N30P, but they are IXYS-products (IXTQ). Don't know are IXYS any good though have some matched IRFP's also from previous projects.

I've used those exact IXYS FETs in one of my amps and was pleased with the result. They seem to make a pretty decent matched pair.

 

[xrk971]

ALPHA 20W BOM v1

Thank you to Zman01 for helping me put this BOM together for the ALPHA 20W amp.

XLS and PDF formats attached, and plain text below.

ALPHA 20W Class A Amplifier BOM by zman01 and xrk971
Feb. 20, 2018 v1
Position Mouser # Mfg # Product Description
R101 594-5063JD2K200FT MBA02040C2201FRP00 Metal Film Resistors - Through Hole .4watt 2.2Kohms 1% 1/8watt body size
R102 594-MRS16000C2202FRP MRS16000C2202FRP00 400 mW Thin Film Resistors 22Kohms 1% 50ppm
R103 594-MRS25000C3301FCT MRS25000C3301FCT00 Thin Film Resistors .6watt 3.3Kohms 1%
R104 594-MRS16000C6801FC1 MRS16000C6801FC100 400 mW Thin Film Resistors 6.8Kohm 1% 50ppm
R105 81-PV36Y202C01B00 PV36Y202C01B00 Trimmer Resistors - Through Hole 2.0Kohms 10mm Square 25turn
R106 594-5063JD220R0F MBA02040C2200FC100 Metal Film Resistors .4watt 220ohms 1% 1/8watt body size
R108 594-5063JD470R0F MBA02040C4700FC100 Metal Film Resistors .4watt 470ohms 1% 1/8watt body size
R111 594-5063JD820R0F MBA02040C8200FC100 Metal Film Resistors - Through Hole .4watt 820ohms 1% 1/8watt body size
R112 594-5063JD220K0F MBA02040C2203FC100 Metal Film Resistors .4watt 220Kohms 1% 1/8watt body size
R113 588-OK2235E-R52 OK2235E-R52 Carbon Film Resistors 22K Ohm 1/4W 5% 250 Volt
R121 594-5063JD1K400F MBA02040C1401FC100 Metal Film Resistors .4watt 1.4Kohms 1% 1/8watt body size
R122 594-5063JD2K200F MBA02040C2201FC100 Metal Film Resistors .4watt 2.2Kohms 1% 1/8watt body size
R123 594-5063JD1K500FT MBA02040C1501FRP00 Metal Film Resistors - Through Hole .4watt 1.5Kohms 1% 1/8watt body size
R124 594-5063JD100K0FT MBA02040C1003FRP00 Metal Film Resistors .4watt 100Kohms 1% 1/8watt body size
R125 652-3296W-1-204LF 3296W-1-204LF Trimmer Resistors - Through Hole 3/8" 200Kohms Sealed Vertical Adjust
R126 594-5063JD220R0F MBA02040C2200FC100 Metal Film Resistors .4watt 220ohms 1% 1/8watt body size
R1270 81-PV36Y202C01B00 PV36Y202C01B00 Trimmer Resistors - Through Hole 2.0Kohms 10mm Square 25turn
R127 594-5063JD1K400F MBA02040C1401FC100 Metal Film Resistors .4watt 1.4Kohms 1% 1/8watt body size
R128 594-5063JD680R0F MBA02040C6800FC100 Metal Film Resistors .4watt 680ohms 1% 1/8watt body size
R129 594-5063JD220R0F MBA02040C2200FC100 Metal Film Resistors .4watt 220ohms 1% 1/8watt body size
R131 756-W21-R33JI W21-R33JI Wirewound Resistors - Through Hole 3Watt 0.33 ohm 5% 75ppm
R132 756-W21-R33JI W21-R33JI Wirewound Resistors - Through Hole 3Watt 0.33 ohm 5% 75ppm
C101 505-FKP2D002201D00HA FKP2D002201D00HA00 FKP - Film Capacitors 220 pF 100 VDC 2.5%
C102 555-RFS35V100ME3#5 RFS-35V100ME3#5 Aluminum Electrolytic Capacitors - Leaded 10uF 35V 20% Audio SILMIC II
C103 598-476CKE050M 476CKE050M Aluminum Electrolytic Capacitors - Leaded 47uF 50V 20%
C1020 Bypass 871-B32523Q1225K B32523Q1225K000 22.5mm LS Film Capacitors 2.2uF 100volts 10%
C1020 (alternate) 75-MKP1848610914P2 MKP1848610914P2 Film Capacitors 10uF 1100volt 5% 2pin 37.5mm LS
C1021 80-PHE426HR8100JR6L2 PHE426HR8100JR06L2 Film Capacitors 250volts 10uF 5% LS 37.5mm
C1022 871-B32672P6105K B32672P6105K Film Capacitors 1.0uF 10% 630Vdc MKP PFC, LS 15MM
C105 581-12061A180FAT2A 12061A180FAT2A Multilayer Ceramic Capacitors MLCC - SMD/SMT 100V 18pF C0G 1206 1%
C111 555-RFS50V102MK9#5 RFS-50V102MK9#5 Aluminum Electrolytic Capacitors - Leaded 1000uF 50V 20% Audio SILMIC II
C112 505-MKP2J021001E00MS MKP2J021001E00MSSD Film Capacitors 0.01 uF 630 VDC 20%
C113 581-12061A180FAT2A 12061A180FAT2A Multilayer Ceramic Capacitors MLCC - SMD/SMT 100V 18pF C0G 1206 1%
C115 505-MKS2C041001FJC00 MKS2C041001F00JC00 Film Capacitors 1uF 63 Volts 5%
C121 505-MKS4C041002EKSSD MKS4C041002E00KSSD Film Capacitors 1uF 63 Volts 5%, 7.5mm Lead spacing
C122 647-UFG2A221MHM UFG2A221MHM Nichicon Aluminum Electrolytic Capacitors - Leaded 220uF 100 Volts 20% Tol.
C122 alternate 555-RFS35V221MI6#5 RFS-35V221MI6#5 Elna Simic II electrrolytic 220uF 35v
C128 647-UFG2A221MHM UFG2A221MHM Nichicon Aluminum Electrolytic Capacitors - Leaded 220uF 100 Volts 20% Tol.
C128 alternate 555-RFS35V221MI6#5 RFS-35V221MI6#5 Elna Simic II electrrolytic 220uF 35v
C127 505-MKS2C041001FJC00 MKS2C041001F00JC00 Film Capacitors 1uF 63 Volts 5%
V101 512-KSA992FBU KSA992FBU Bipolar Transistors - BJT PNP Epitaxial Sil
V102 512-KSA992FBU KSA992FBU Bipolar Transistors - BJT PNP Epitaxial Sil
V103 512-KSC1845FTA KSC1845FTA Bipolar Transistors - BJT NPN Epitaxial Sil
V121 512-BC547CBU BC547CBU Bipolar Transistors - BJT NPN 45V 100mA HFE/800 - TO-92-3
V131 844-IRFP240PBF IRFP240PBF MOSFET N-Chan 200V 20 Amp
V132 844-IRFP9240PBF IRFP9240PBF MOSFET P-Chan 200V 12 Amp
D035 78-1N4148 1N4148TR 500 mW Diodes - General Purpose, Power, Switching 100V Io/150mA T/R
X141, 142, 143, 144, 131, 132 534-1287 1287 Keystone Terminals .250" PCB TERMINAL
X101 571-3-641213-2 3-641213-2 TE Connectivity - Headers & Wire Housings POLARIZED HEADER 2P Straight Post gold

 

[AKSA]

This is a mightly BOM - thank you Zia, and X. I am very grateful to both of you!
This is the definitive BOM for the ALPHA. Along with the schematic and JPS brilliant pcb design we have a workable Class A which I hope will stand proud along Nelson's wonderful designs to many DIYers to build into the decades........

Now we wait until the reviews roll in from the many forum enthusiasts building at present...... I hope it joins the memorable amps like the Monster, the Zens and the JLH 10W!

Hugh

 

[xrk971]

GB Status Update...

I am packing boards and printing shipping labels finally. Sorry this took longer than usual - it's lunar new year here in Northern Virginia and I have family in town for past week.

If you paid me and do not see your name on this list, please let me know. Or if I have the quantity incorrect etc. It is up to you to double check the order accuracy listed here as I have so many to fill... I am bound to make mistakes.
Thanks,
X

Pinocchio - 1 pair, Sent
6L6 - 1 pair, Sent
bk856er - 1 pair, Sent
Vunce - 2 pairs, Sent
Pcgab - 1 pair, Sent
jwjarch - 1 pair, Paid
vvs07 - 2 pairs, Paid
jacques antoine - 1 pair, Paid
GnuB - 1 pair, Paid
Kokanee - 2 pairs, Paid
zman01 - 1 pair, Paid
Bvtrinh - 1 pair, Paid
MshipmanPE - 1 pair, Paid
muthumuthiah - 1 pair, Paid
Schlomoff, 1 pair, paid
markus22ch - 1 pair, Paid
manniraj - 2 pair, Paid
Juntuin - 1 pair, Paid
Aatto - 1 pair, Paid
Wayne1 - 1 pair, Paid
Soelker - 1 pair, Paid
Touchdown - 1 pair, Paid
CFT - 1 pair, Paid
roger57 - 1 pair, Paid
Dane -1 pair, Paid
Gaborbela - 1 pair, Sent
wtl - 1 pair, Paid
Emynet - 1 pair, Paid
hajj - 1 pair, Paid
alibear - 1 pair, Paid
redarc12 - 1 pair, Invoice sent

35 pairs, 70 boards total.

 

[xrk971]

This is a mightly BOM - thank you Zia, and X. I am very grateful to both of you!
This is the definitive BOM for the ALPHA. Along with the schematic and JPS brilliant pcb design we have a workable Class A which I hope will stand proud along Nelson's wonderful designs to many DIYers to build into the decades........

Now we wait until the reviews roll in from the many forum enthusiasts building at present...... I hope it joins the memorable amps like the Monster, the Zens and the JLH 10W!

Hugh

Hi Hugh,
I have built and listened to a lot of amps (about 30 I think, I lost count...) and this amp certainly is up there among the best I have heard, perhaps the best under 50w amp even. I have no doubt it will be an enduring classic. Thank you for the topology and design. JPS64 also deserves huge thanks for the masterful professional layout. I am looking forward to hearing reports back from Vunce and Pcgab once they get fired up with stereo speakers.
Cheers,
X

 

[Vunce]

I am fired up with stereo speakers!!
After messing around with the SMPS bricks some more without success, I scraped the plan.
I put together a traditional linear power supply with components on hand and fed both ALPHA boards 22vdc.
SUCCESS!! Sweet music from both channels. Even with my pieced together power supply you can get the feeling that this is a special amplifier.
Words of advice, do not skimp with heatsinking. Even at 22vdc the ALPHA gets warm/hot rapidly. I planned to use forced cooling with the cpu coolers anyway.
With the proper power supply treatment, this amplifier is going yo ROCK
I tend to agree with X, “no doubt it will be an enduring classic”.


Thank you Hugh and X for bringing the ALPHA to the DIYA forum

JPS64, your amazing layout/design and board quality is first rate!! Thanks.

 

[zman01]

This is a mightly BOM - thank you Zia, and X. I am very grateful to both of you!
This is the definitive BOM for the ALPHA. Along with the schematic and JPS brilliant pcb design we have a workable Class A which I hope will stand proud along Nelson's wonderful designs to many DIYers to build into the decades........

Now we wait until the reviews roll in from the many forum enthusiasts building at present...... I hope it joins the memorable amps like the Monster, the Zens and the JLH 10W!

Hugh

Hugh,

Many thanks to you for sharing the design with the diyA community. X is a prolific amp builder and has listened to many good amps before the ALPHA; but he is mighty impressed with this one, so expecting that the folks building this amplifier will be in for a treat.

X helped me put together the bill of materials for ordering from Mouser. I am planning to place my order for the parts today. The beautiful PCBs with layout done by JPS64 should reach me early next month.

Feeling excited!

 

[zman01]

I am fired up with stereo speakers!!
After messing around with the SMPS bricks some more without success, I scraped the plan.
I put together a traditional linear power supply with components on hand and fed both ALPHA boards 22vdc.
SUCCESS!! Sweet music from both channels. Even with my pieced together power supply you can get the feeling that this is a special amplifier.
Words of advice, do not skimp with heatsinking. Even at 22vdc the ALPHA gets warm/hot rapidly. I planned to use forced cooling with the cpu coolers anyway.
With the proper power supply treatment, this amplifier is going yo ROCK
I tend to agree with X, “no doubt it will be an enduring classic”.


Thank you Hugh and X for bringing the ALPHA to the DIYA forum

JPS64, your amazing layout/design and board quality is first rate!! Thanks.

Vunce,

Good to know you are up and running. If I may ask, what speakers are you using with the ALPHA?

Speaking of heat, I got some big heat sinks for my build - 12" x 10.5", 3.5 Kgs each... hope that will be enough as passive radiators.

 

[bk856er]

This is a mightly BOM - thank you Zia, and X. I am very grateful to both of you!
This is the definitive BOM for the ALPHA. Along with the schematic and JPS brilliant pcb design we have a workable Class A which I hope will stand proud along Nelson's wonderful designs to many DIYers to build into the decades........

Now we wait until the reviews roll in from the many forum enthusiasts building at present...... I hope it joins the memorable amps like the Monster, the Zens and the JLH 10W!

Hugh

+1 thanks to Zia and X for the BOM!


BK

 

[Vunce]

Hi Zman01,

On the test bench I’m using a pair of diy Speedster’s designed by Paul Carmody.
They are not very efficient but sound extremely good.
The ALPHA will eventually get into the main system and there it will drive a set of highly modified old school Klipsch Forte l .

I think your heatsink will be just fine

Happy ALPHA building

Vunce

 

[hajj]

The beauty of this design lies in its simplicity and the fact that unlike Nelson's designs, it does not rely on unobtanium parts.
I currently have 3 Pass boards, only one of which is functional due to the scarcity and cost of the active components.

No matter how you look at this design thought, it ticks all the right boxes:

- Class A
- 20W, and easily scalable (making it suitable for a wider range of speakers)
- Easy to build and setup
- Easy to source parts
- Excellent specs and distortion profile
An amateur class A builder's dream amp

Can't wait to get the boards and start building away.

Thank you Hugh, X and JPS

 

[xrk971]

SUCCESS!! Sweet music from both channels. Even with my pieced together power supply you can get the feeling that this is a special amplifier.

Congratulations on stereo success, Vunce! And thank you for building so quickly - you are the proverbial, Guinea pig/Beta tester. With your success, I feel very good about shipping the boards out tomorrow.


Any more photos? I assume you are using your 99dB Klipsch Forte's?