Aleph J illustrated build guide

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#7,441
Could someone be as kind as to make some suggestions for alternatives to the backordered parts? Or, if you just disagree with anything here, I am open to substitutes. I'm not trying to be lazy as much as making sure I don't try to pick something I think will work the same...and it is not.

--For the 8 big power supply caps, I understand 15,000uF 25V are the default choice...and people usually go bigger. What is the tie breaker? This one is rated for 105C and 3000 vs. 2000 hours, but no idea if that really matters for this application. Should I go bigger than 18,000uF?
https://www.mouser.com/ProductDetail/Nichicon/LGU1E183MELA?qs=UR%2BAsA3ox60PA5d/1RtjLw==

--For C2, C3...this? Or something else?
https://www.mouser.com/ProductDetail/Nichicon/UKW1V221MPD?qs=kArNe9LFxXmPUS3jaaLENQ==

--For C4...everything similar looks to be backordered, showing up as a November arrival:
RFS-35V100ME3#5 Elna | Mouser

--No idea on this: 39890-0303 Molex | Mouser

*****

Saved cart from: Parts: the Rest of the BOM

The saved cart itself: https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=35ACFA214D
 
#7,442
andynor said:
I am not putting a condom on the outputs before my first set of speakers burn out. Then I will wisen up, for sure. Just my way, in stead of learning the smartest way beforehand.

Canonken, what for example can happen is if a rail/half/part of the amp or one or more components fail, the DC offset can be severly affected, sending several volts of DC directly into the speakers. Voice coils don’t like that. Probably a terrible explanation, but basically that is more or less what can happen. A bunch of stuff CAN go wrong of course, as with everything in life.

You should do what you feel is best and safe enough for you. Doing it or not, it’s just risk management. It basically comes down to how much risk you willing to take. Risk being a result of likelyhood and consequence, where your chosen circuit plus your skills make up the likelyhood, and the consequence made up basically of dollars you are willing to loose should it go wrong.

I know prople who lost A LOT of money cuz of voice coil burnouts, expensive speakers, and not with DIY amps either. No one can decide for you what risk you are willing to take. Safest way is to use one.

Regards,
Andy
Click to expand...

Thanks, helpful. It is telling if the actual commercial Pass/FW products did not include it, seems to suggest the risk is low (again understanding the amp needs to be properly built). I just have no idea if this is a 1 in a million chance (things can always happen), or if it IS going to happen on the amp as parts wear out and you are just living on borrowed time. Especially in the winter, I can see using this amp a lot.

My main speakers are discontinued, but the closest replacement are these, not something I would be happy about buying due to an amp failing: New Compact 3-way Loudspeaker Olympica Nova II | Sonus faber
 
#7,444
Zen Mod said:
Thiele/Small parametre for Tannoy 3859



Coil restistance 4.81 (ohm)
Force factor ( BL) 12.67 (newton/ampere)
Total suspension compliance 0.08 (millimetre/newton)
Moving mass 61.21(gm)
Mechanical resistance 9.57 (mechanical ohm)
Effective radiating area 804.85 (square centimetre)
Shove 33.36 (newton second/metre)
Resonant frequency 70.50 (hertz)
Mechanical Q 2.83
Electrical Q 0.81
Total Q 0.63
Sensitivity 96.23 (dB SPL/2.8 volt à 1m) à 20degC
Equivalent volume compliance 75.60 (litre) à 20degC

made for wedge monitors and Cougar small box

no bass to speak of, so it must be augmented with bass helper

ideal for biiiiiiiig OB, with one or 2 15" bass helpers per side

though, rejuvenation (or replacement) of cloth surround inevitable
Click to expand...

Thanks a lot, Mighty!

So, not complete audiophile retirement without speakers so big my wife will replace me if I bring them in here :rofl:

I’ll keep looking around. Not often I come across such drivers around here, and a pair of those with Cougars turned up today.
 
#7,450
andynor said:
Thanks a lot, Mighty!

So, not complete audiophile retirement without speakers so big my wife will replace me if I bring them in here :rofl:

I’ll keep looking around. Not often I come across such drivers around here, and a pair of those with Cougars turned up today.
Click to expand...

damn greenhorns :rofl:

Sweden, Denmark, Norway

I can bet that you'll find at least 3 opportunities in 3 months, pair of 15" up to 800E

widen up that to Vaterland and Unterland ('Olanda) ........ go figure
 
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#7,452
CL60's max current rating is higher than an Aleph J needs. According to the Aleph J manual on First Watt's website, power consumption from the AC mains is 200 watts. In 115VAC applications that's 1.7 amperes. So Aleph J prefers an inrush current limiter device with a max current rating of 2 or 3 amps.

CL60's resistance-versus-temperature is lower than what you want, to make sure inrush currents don't blow your mains fuse. Steady state current is 1.7 amperes, you don't want inrush current to be gigantically bigger than that. Creating a design goal by means of rectal extraction, suppose you want inrush current to be less than 2.5X higher than steady state. Then inrush current = 2.5*1.7 = 4.2 amperes, and total resistance = 115V/4.2A = 27 ohms. To satisfy this rectally extracted design goal you'd need an inrush current limiter device with a cold resistance of 27 ohms or more. However the CL60's cold resistance is only 10 ohms.
 
#7,453
And in a 230v application, it would seem like the CL-60 is an even iller fit, or is it the other way around? For my dual mono build (2x60’s) that means I need an R of hundreds to ensure max 2,5x inrush…

But to flip it towards temp, how will the CL-60 fair temp/resistance-wise DURING hot operation on 115VAC and 230VAC? From what you are saying, I gather using 60’s in a dual mono build on a 230VAC line more or less quadrouples the problem? If I got it right, which ai orobably didn’t :cheers:
 
#7,455
Who picked the CL60 in the first place...and why? As in, did that person do the math, and it works for this application? Could there be other (unwanted) impacts to the system by changing it even if a different part initially seems better?

Semi-related, if you are using bigger caps for the power supply (for example, 22,000uF vs. the default 15,000uF), does that mean it will take longer for those to get fully charged when turning on the amp...or it is near-instant? Seems people have used 15-22k (or larger?) caps and it does not have any negative impact, correct?
 
#7,456
There are many factors and compromises, all dependent on the designer's (NP) thoughts and requirements.

Higher resistance means higher voltage drop and higher temperature and power dissipation, but better current control.

More capacitance will take longer to charge. The maximum current if no thermistor or other current limiting device is in place is dependent on the power transformer's maximum current capability (transformer VA).
 
#7,458
I am gonna use CL60’s in a dual mono with approx 0.8F capacitance, and I know it is going to work, based on Mighty’s and others advice and experience, for example Chede. But Mark raises interesting points. But lets say the CL60 is not the perfect solution, is it not good enough? It most likely is. Then there is the point of what audible negative effect it’s imperfectipns might have? I would think small, but I have no math to show this. Other than that plenty people make it work well enough. Two points I am going to look at, inevitable and optional:

1: does my mains fuse blow or the lights blink a bit too much?

2: Do the NTCs heat properly during operation so that I don’t loose to many volts before the tranny.

Wear and tear on the caps will prolly come as a punishment, some day, maybe…

Regards,
Andy
 
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