Aksa Lender P-mos Hybrid Aleph (ALPHA) Class A Amp GB

[xrk971]

Alpha B.B. GB Status Update.

*pelayostyle - 1 set
pcgab - 1 set bb, 1 set TO-264 insulator pads, Paid
vvs07 - 3 sets bb, 3 sets TO-264 insulator pads, Paid
emynet - 1 sets bb, 2 sets TO-264 insulator pads, Paid
DrPro - 1 set bb, 1 set TO-264 insulator pads, Paid
wtl - 1 set bb, 1 set TO-264 insulator pads, Paid
yoaudio - 1 set bb, 1 set TO-264 insulator pads, Paid
*markus22ch - 1 set bb, 1 set TO-264 insulator pads
Cambe - 1 set, 1 set of TO-264 insulator pads, Paid
ekidnah09 - 1 set bb, 1 set of TO-264 insulator pads, Aksa Lender Pre with TH, Paid
Kokanee - 1 set bb, 1 set of TO-264 insulator pads, Invoice Sent
Vunce - 1 set bb, 1 set of TO-264 insulator pads, Paid
bvtrinh - 1 set bb, 1 set of TO-264 insulator pads, Paid
muthumuthiah - 1 set bb, 1 set of TO-264 insulator pads, ship to US address TBD, Paid

Thanks to all the folks who have paid. I will prepare the orders now.

 

[Kokanee]

Hi X,

I am going to pay you immediately. Please hold the shipment until I contact you in June. After I contact you, then you can send to Idaho depot.

Thanks everyone for all their help and knowledge that I have benefited from.

Best regards,

Myles

 

[xrk971]

Thanks, Myles. I will hold it as you request.

 

[pcgab]

I'm not so sure I find the "13-level scale" odd, in fact I think it is much better than, say, a five-point or 10-point scale.

The problem with the fixed scales is one of time, not steps. Last year's "10" is bettered by this year's "9", yet there is no way to "move" last year's 10 down to 8 (or wherever it belongs).

A similar scale, Stereophile's well known Class A. B, C scale partly, and clumsily, acknowledges this problem by now having a Class A+, and by dividing Class A into subclasses such as for loudspeakers (with and without very low frequency extension), yet does not solve it. A "Stereophile Class A" rated product will wear the badge forever, yet one of 20 years ago (or maybe five, if we are talking certain digital products) may be able to compete with that of today, or may pale in comparison. There is no true distinction.

A "13-step" scale solves this problem neatly. It isn't, actually, a 13-point scale at all; in theory it is near infinite, in practice considerably less so, but none the less not limited to 13 steps.

Next year could bring one cap that deserves a grade of 14, as in it's better than today's 13 graded cap, and there is no need to adjust your system for products of previous generations. A 9 is still a 9, and is still graded the same in relation to the 13-grade, the 5-grade, and if it deserves being created, the 14-grade. I quite like it, actually.

You're absolutely right, I do prefer more points for _potentially_ more fine grained grading. Though, being purely subjective, there are many grains of salt to be taken with the lot of it.

I still swear by the clarity caps, and the Cornell Dubillier 940/942, etc. series. I'm sure there are better ones out there that have all manner of metaphor associated with them, maybe I'll even try some of those some day....

Cheers,
Gable

 

[watchtmouse]

Please correct the BOM for R121 / C103

Hi X,

I know BOM's are a boring, but ...

In the BOM of the 8R, Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier 20 Watts, on the First page of this thread it is listed:

• R121 594-5063JD1K400F MBA02040C1401FC100 Metal Film Resistors .4watt 1.4Kohms 1% 1/8watt body size
• C103 598-476CKE050M 476CKE050M Aluminum Electrolytic Capacitors - Leaded 47uF 50V 20%

However you have confirmed in the "Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier" thread, Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier

That R121 (Hugh R8) definitely needs to be a 1K Ohm Resistor,
I noticed this on verifying my ordered parts against the schematic(s) / BOM.

For C103, AKSA confirmed at Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier that 470 uF 50 V is a valid value that wil fit the 10 mm diameter and the RM 5 mm for C013.

Sorry for not supplying MOUSER part numbers ( I must say that I am a bit afraid to list part numbers here, since selecting parts is not a simple thing, so I ask the builder that are more confident in selecting parts to help here )

For reference and future builders can you please correct the BOM.

Thanks in advance

Happy listening

Bert

 

[irribeo]

BOM for v2 BB tells 47r snubber resistor is both thick film and Panasonic thin film

 

[xrk971]

Hi X,

I know BOM's are a boring, but ...

In the BOM of the 8R, Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier 20 Watts, on the First page of this thread it is listed:

• R121 594-5063JD1K400F MBA02040C1401FC100 Metal Film Resistors .4watt 1.4Kohms 1% 1/8watt body size
• C103 598-476CKE050M 476CKE050M Aluminum Electrolytic Capacitors - Leaded 47uF 50V 20%

However you have confirmed in the "Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier" thread, Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier

That R121 (Hugh R8) definitely needs to be a 1K Ohm Resistor,
I noticed this on verifying my ordered parts against the schematic(s) / BOM.

For C103, AKSA confirmed at Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier that 470 uF 50 V is a valid value that wil fit the 10 mm diameter and the RM 5 mm for C013.

Sorry for not supplying MOUSER part numbers ( I must say that I am a bit afraid to list part numbers here, since selecting parts is not a simple thing, so I ask the builder that are more confident in selecting parts to help here )

For reference and future builders can you please correct the BOM.

Thanks in advance

Happy listening

Bert

Thanks, Bert. I made updates. C103 doesn’t see full rail voltage so could be 35v even. But larger value prevents turn on thump. 470uF is fine.

 

[xrk971]

I just placed the order for the Alpha BB v2 GB boards.

 

[Johnny2Bad]

You're absolutely right, I do prefer more points for _potentially_ more fine grained grading. Though, being purely subjective, there are many grains of salt to be taken with the lot of it.

I still swear by the clarity caps, and the Cornell Dubillier 940/942, etc. series. I'm sure there are better ones out there that have all manner of metaphor associated with them, maybe I'll even try some of those some day....

Cheers,
Gable

There is nothing wrong with the Clarity caps; many otherwise very well regarded products get by with more mundane varieties. As always, the circuit and layout are the more important parts; a poorly designed amp can stuff all the high dollar parts it wants and it still is a poorly designed amp, and will show it.

In that respect the "tin-eared EE" has something to say for himself. Where he fails is not in effort but in denying there could be any improvement at all when others hear differently.

DIY'ers sometimes use the cost advantage they have* (although it's not as high as it could be, with volume pricing not in our favour) to throw boutique parts at a project without proper evaluation of what's there already. That is our problem and our failing.

In the end both are needed and both should complement each other. There is no winner, only losers, when a side is taken without regard to the other perspective.

I think this particular project illustrates that rather well. Start with an excellent design, an excellent layout, and see what that gets you. Substitutions can then be attempted, with proper evaluation, to see if and where improvements can be made. It would not surprise me to learn either possible outcome to be true ... it's good as it is, or it might benefit from judicious parts substitutions.

Unfortunately, I have way too many projects on the go to talk myself into jumping in on this one. Maybe a later GB, if such exists. Good luck to all on your AKSA/ALEPH builds.

* Anyone who gets into DIY "to save money" will soon discover the error in his logic. Perhaps the best he can hope for is laying out smaller wads of cash over a longer period of time, the "death by a thousand cuts", versus one large purchase. Good thing it's fun.

 

[xrk971]

I am using a Clarity cap in my Aksa Lender headphone amp (preamp with 2SA1837 outputs and higher bias current). It sounds quite nice but unless I do AB testing it’s hard to say conclusively without some placebo bias. I think I hear more top end, but it has noticeable hum pickup if my fingers touch the cap body. It’s quiiey if I don’t touch it. So all that cap foil area makes for a good EMI pickup antenna.

Truth be told, a $0.15 Elna Silmic II 10uF 35v electrolytic is about as much bang for the buck as you can get in this application.

 

[xrk971]

The B.B. boards are almost done with production and onto testing now. There is a holiday in China so everything is going to stop for a few days.

 

[xrk971]

Somehow we must have squeezed in before this holiday coming up because the Alpha BB PCBs have shipped! Should be here in 5 days or so then.

 

[Juntuin]

Ah ****..I missed whole B.B. group buy since its in same topic as Alpha is there any spares, X?

Btw, here is Alpha20 now with way oversized cooling. Frame still on progress but materials bought.

 

[Vunce]

Juntuin,
Are you using the ALPHA as a full range amplifier in your setup?
How tall are your speakers?
Those heatsinks look killer!

Cheers

 

[Juntuin]

Juntuin,
Are you using the ALPHA as a full range amplifier in your setup?
How tall are your speakers?
Those heatsinks look killer!

Cheers

Alpha is driving only those 15" JBL's at the moment (active xo, 20hz-800hz), but I'm in transition to passive but bi-amp them "soon". Amp is about 1 meter tall theres huge feeling of power compared to previous Class-AB amp even it " lacks" watts!

My plan is to drive lower end with B.B. and horns with Alpha. B.B. might get that enclosure you can see in picture (if I did not missed GB totally...). Those sinks can handle over 60w Class-A easily, tested.

And yeah, really should finish those speakers finally too. Too many projects at the same time

 

[Vunce]

That’s a great plan! The ALPHA’s should have a similar sound characteristic since they share some circuit design.
I’m sure X has a few unaccounted for BB pcb’s

 

[Juntuin]

Let's hope so Vunce

 

[xrk971]

Ah ****..I missed whole B.B. group buy since its in same topic as Alpha is there any spares, X?

Btw, here is Alpha20 now with way oversized cooling. Frame still on progress but materials bought.

No problem, Juntuin. I have more - will send you invoice. Please PM me your PayPal address again. I assume you want the ceramic TO264 insulators too?

Glad to hear the Alpha 20 is powering your woofer now, and you say it has power. Waiting till you hit it with the Alpha BB.

Better take cover or plaster from ceiling may fall...

 

[Juntuin]

No problem, Juntuin. I have more - will send you invoice. Please PM me your PayPal address again. I assume you want the ceramic TO264 insulators too?

Glad to hear the Alpha 20 is powering your woofer now, and you say it has power. Waiting till you hit it with the Alpha BB.

Better take cover or plaster from ceiling may fall...

Good to hear definitely with insulators! PM send.

This will probably be my last diy-effort, tired of building everything on bedrooms floor. But I'll put my last efforts on this frame, will there be Alpha20 or B.B., let's see

 

[xrk971]

That’s one reason I build speakers out of foam core. I don’t have a workshop for wood work. But electronics building is easier and cleaner. Wooden speaker boxes go out to a cabinet maker who can do a much better job than me.