Aleph 4 Strickly DIY Project Build

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Russellc

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Bill Fuss said:
There is a little more to it than adding output fets but that is the basics. I would suggest buying a few sets, building a mini to get familiar with the Aleph circuitry, then plan your big one with help from the forum. You can do 90 watts into 4 ohms with the Aleph 5. You can do 60 into 8 ohms with the Aleph 60. You can use jfets in the front end if you like, the options are almost limitless.
Click to expand...

My Chip amp Aleph boards came today. I'll order a couple of more sets. What you suggest is exactly what I had in mind....a Mini, them Aleph 30 or 60. If that flies, maybe up to Aleph 4, but that's likely larger than I want to go. thanks for athe answers, I'm sure I'll have lots of questions when the time comes.

Thanks again,

russellc
 
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Andy5112405

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Joined 2006
To be perfectly honest, my A700 is capable of 60Watts/Channel but I very rarely use it avove the penultimate click of the ladder attenuator. The B&W 683s are about 90dB/Watt and at that setting the amplifier is running at:

BELEIVE IT OR NOT

A measly 5.8Watts. And it is perfectly loud enough to annoy the neighbors.

I only went for the Aleph 4 as I was annoyed that my so called Class A amplifier only runs at Class A until about 17Watts or so.

The difference in listening pleasure at 5.8W and 58W is quite considerable, but how much of that is simply due to it being too loud to be comfortable and how much is it due to the class of operation.
 
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Russellc

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Joined 2003
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Andy5112405 said:
To be perfectly honest, my A700 is capable of 60Watts/Channel but I very rarely use it avove the penultimate click of the ladder attenuator. The B&W 683s are about 90dB/Watt and at that setting the amplifier is running at:

BELEIVE IT OR NOT

A measly 5.8Watts. And it is perfectly loud enough to annoy the neighbors.

I only went for the Aleph 4 as I was annoyed that my so called Class A amplifier only runs at Class A until about 17Watts or so.

The difference in listening pleasure at 5.8W and 58W is quite considerable, but how much of that is simply due to it being too loud to be comfortable and how much is it due to the class of operation.
Click to expand...

Yes, I'm slowly learning that lesson with my F-5. With even my most inefficient speakers, there is plenty of volume for most all listening needs.
I think it was the psychological effect of not having any more on tap or something.

My other speakers are around 91, 93 and 100+, they are fine. With a pre amp with gain in front of the F-5, there is no problem for sure.

Russellc
 
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Russellc

Member
Joined 2003
Paid Member
Bill Fuss said:
There is a little more to it than adding output fets but that is the basics. I would suggest buying a few sets, building a mini to get familiar with the Aleph circuitry, then plan your big one with help from the forum. You can do 90 watts into 4 ohms with the Aleph 5. You can do 60 into 8 ohms with the Aleph 60. You can use jfets in the front end if you like, the options are almost limitless.
Click to expand...

I also took your advice and bought a few more.

Russellc
 
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Andy5112405

Banned
Joined 2006
One divorce later - miserable ***. I've now got all the time in the world to finish the Aleph 4.

The Borbelly pre-amplifier, I wasn't impressed with. It was excellent but definitely added colouration to the signal that wasn't there with a passive pre-amp.

I'm now finishing a Shuntky / Pumpkin pair to see how they compare with a passive stage.

The problem is that the F4 has no gain so I need a pre-amp of one kind or another with about 10 - 15X voltage gain.
 
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Andy5112405

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Joined 2006
Quick question about LEDs before I rip the Pumpkin apart again.

D1 to D6 are all in series so share the same current.

2 of the LEDs illuminate the other 4 don't. Is this likely to be faulty LEDs or do LEDs conduct if they are inserted the wrong way round ? I'm sure that I got them all correctly orientated but I'm not 10000% sure. The only sure way to check them is to replace them as they are in double sided board and are not easy to remove.
 
Zen Mod

Zen Mod

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if leds are in series ( and on Pumpie they are ) - if some are lit and some are not - those non-lit are dead one but conducting .... because other ones are lit .

dunno what and how ;

in case that you put just one of 6 backwards , none will be lit


what's voltage across R24 ?

for programmed current of 3-6mA it must be in range of 270x3(6)mA = 0V81(1V62)

easiest way to desolder them is - heat both solder pads of LED in same time and pull it out ; later clean holes with solder sucker
 
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Andy5112405

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I'm at a loss at the moment. All LEDs are OK and all are inserted the right way round. With the Pumpkin removed from any other devices, i.e completed PCB in isolation. I can apply a 10mA external supply across the LED chain. LEDs 1-4 illuminate and LEDS 5-6 illuminate but never all 6. It's not a function of the voltage applied as I can apply the constant current to any combination of the LEDs. One would assume that there is a break between LED 4 and LED 5 but it all measures correctly. I thought Q9 might be faulty but the symptoms are the same with Q9 removed. Continuity between all the LEDs seems OK and there doesn't seem to be any extraneous copper.

Is witchcraft to blame ?
 
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Andy5112405

Banned
Joined 2006
Found it.

There was a tiny short between the trace that goes to the base of Q9 and the bottom end of D4.

I'll repair the board and see if that has caused any other damage.

By the way, should the adjustment of W2 to give 0V at the outputs be so fine. I've only got to breathe on the pot and it swings from almost +Vcc to -Vcc.
 
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