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Hi Zen Mod,
Whit a phase shift in mind, could you help me understand C1... and its influence on only one half of a differential input signal.
My understanding is that it's there to protect the pre-amp in case of a catastrophic failure of either output transistor. However, the cap will shift the phase of an incoming inverting (-) half of a differential signal; worst yet, the phase shift will be non-linear with respect to a frequency spectrum. So, would it be better to introduce the same value capacitor in series with a non-inverting (+) signal, to introduce the same phase-shift as in inverting half, if one wants to feed the amp with the differential signal?
I have used 50w Aluminum heatsinked power resistors clamped to the heatsink and a power supply to check for temp rise. I put some HS compound on the resistor and use a C clamp to secure it to the sink. Then use a power supply to feed it the power level you want to dissipate. Wait for it to stabilize and measure the sink temperature. Try to duplicate the physical setup as much as possible. Convection can play a big role in the transfer of heat so if you restrict air flow or allow more than will happen in the actual amplifier your results will not be as accurate.
I think this is what Mighty Zen Mod was saying but I’m still not great at translating ZMeze.
Looking at those 5” cubes my guess is that they will be OK, but because of their unusual aspect ratio it would be good to test things before committing. Using 3 with a heat spreader may be more work than it’s worth. You could always mount them inside the chassis and fan cool the amp which is what I did with my J. I used the sinks I had on hand which were not going to cut it without some help.
Here’s what that ended up looking like.
Another Aleph J, fan cooled, LC filtered supply
It runs at about 45C. This configuration allows you to directly mount the fets to the sink for better heat transfer, but of course you must isolate the heatsinks from chassis and each other and protect them from any outside metal objects that could cause a short.
I think this is what Mighty Zen Mod was saying but I’m still not great at translating ZMeze.
Looking at those 5” cubes my guess is that they will be OK, but because of their unusual aspect ratio it would be good to test things before committing. Using 3 with a heat spreader may be more work than it’s worth. You could always mount them inside the chassis and fan cool the amp which is what I did with my J. I used the sinks I had on hand which were not going to cut it without some help.
Here’s what that ended up looking like.
Another Aleph J, fan cooled, LC filtered supply
It runs at about 45C. This configuration allows you to directly mount the fets to the sink for better heat transfer, but of course you must isolate the heatsinks from chassis and each other and protect them from any outside metal objects that could cause a short.
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Hi Brian: I like the recycled approach - I did the same with my M2 amp, using old/left over parts from other projects where I could. That one image of the corner of your amp and the way the light reflects makes it look like your handles are molded into/part of your front panel. I did a double-take when I first saw that image.
I think 2 sinks/channel will work, but I'm expecting final temps near 60c. Mounting sinks with a spreader bar isn't too much hassle (the sinks are channeled, so it won't require drilling/tapping for that purpose), but it also eats up 2 sinks I could use for another project... I have also noticed that using some sort of legs to elevate the sinks a few inches does improve convection. I'll start stuffing the boards shortly and see how it turns out. Unfortunately, I don't have any sink-mountable resistors on hand to try a more direct power experiment.
I think 2 sinks/channel will work, but I'm expecting final temps near 60c. Mounting sinks with a spreader bar isn't too much hassle (the sinks are channeled, so it won't require drilling/tapping for that purpose), but it also eats up 2 sinks I could use for another project... I have also noticed that using some sort of legs to elevate the sinks a few inches does improve convection. I'll start stuffing the boards shortly and see how it turns out. Unfortunately, I don't have any sink-mountable resistors on hand to try a more direct power experiment.
Thanks Eric. I collect stuff and it’s always fun to try to take what’s on hand and make it work. Older UPS units that people or businesses are throwing away are a good source of mid sized heatsinks and I actually managed to recycle 2 of the larger chassis into an Aleph J.
Good luck on your J. The hardest part will probably be drilling/tapping and mounting the heatsinks and all the other metal work. I found the J was easy to build and adjust and holds stable bias and offset values. I also built a 4 box F5 turbo monoblock setup which was much harder to adjust.
Good luck on your J. The hardest part will probably be drilling/tapping and mounting the heatsinks and all the other metal work. I found the J was easy to build and adjust and holds stable bias and offset values. I also built a 4 box F5 turbo monoblock setup which was much harder to adjust.
Hi all....
I did it!.....Alpeph J is dead quiet now.....juhuu!
When I tried moving the transformer I discovered that the hum changed with the position.
Especially moving outwards the chassis reduced hum!
So it was apparently no ground issue!
Installing the transformer upright and shielded input wire did the thing!
Still learning....and experiencing....
Thanks all
I did it!.....Alpeph J is dead quiet now.....juhuu!
When I tried moving the transformer I discovered that the hum changed with the position.
Especially moving outwards the chassis reduced hum!
So it was apparently no ground issue!
Installing the transformer upright and shielded input wire did the thing!
Still learning....and experiencing....
Thanks all
Pass DIY Addict
Joined 2000
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Greetings all, here's my first dumb question.
I've started acquiring bits to build the Aleph J. So far bought the Jfets and the Torroidal.
I'm wondering if it will fit in something smaller than the DIY 4u case and I have found one which appears to have sufficient heatsinks.
Aluminum class A amplifier enclosure/amplifier chassis AMP BOX with heatsink | eBay
The internal dimensions are height 112 width 160 length 300
Compared to the massive 4u at ht 165 wdth360 lngth 300
The transformer is 5.1"[round 130mm] dia by 3.1"h
So it seems that it will fit and if so I am really keen on the price. Would it get too hot with that much less space around the transformer?
Your opinions please?
I've started acquiring bits to build the Aleph J. So far bought the Jfets and the Torroidal.
I'm wondering if it will fit in something smaller than the DIY 4u case and I have found one which appears to have sufficient heatsinks.
Aluminum class A amplifier enclosure/amplifier chassis AMP BOX with heatsink | eBay
The internal dimensions are height 112 width 160 length 300
Compared to the massive 4u at ht 165 wdth360 lngth 300
The transformer is 5.1"[round 130mm] dia by 3.1"h
So it seems that it will fit and if so I am really keen on the price. Would it get too hot with that much less space around the transformer?
Your opinions please?
112mm is only 68% of 165mm so there is not enough heatsinking.
Also 160mm width is way too narrow. Besides the transformer width, you need to account for the circuit board on each side including standoffs, and room for rectifiers. Also the narrow width will make it difficult to accommodate an on-off switch and speaker outputs and signal inputs, as the power supply board and transformer will probably take up all of the 300mm length too.
Also 160mm width is way too narrow. Besides the transformer width, you need to account for the circuit board on each side including standoffs, and room for rectifiers. Also the narrow width will make it difficult to accommodate an on-off switch and speaker outputs and signal inputs, as the power supply board and transformer will probably take up all of the 300mm length too.
I'm still on beginner's time delay with posts . The previous post which hasn't been published yet inquired about heatsinks.
I have now tracked some down from Altronics which are 300x75x46.
Thus if I buy 4 and stack them in two pairs I will have more surface area than the 4U.
I calculate the 4u at 300x171x40 which is 2,052,000
While the Altronic stacked per side are :
300x150x46 which comes to 2,070,000
They look similar though may not have the rippley surface of the 4u.
They are $25 each if you buy 4.
Here's the link.
https://www.altronics.com.au/p/h0545-300-x-75-x-46mm-diecast-heatsink/
I have now tracked some down from Altronics which are 300x75x46.
Thus if I buy 4 and stack them in two pairs I will have more surface area than the 4U.
I calculate the 4u at 300x171x40 which is 2,052,000
While the Altronic stacked per side are :
300x150x46 which comes to 2,070,000
They look similar though may not have the rippley surface of the 4u.
They are $25 each if you buy 4.
Here's the link.
https://www.altronics.com.au/p/h0545-300-x-75-x-46mm-diecast-heatsink/
I have some questions about the Aleph J power supply.
Firstly it seems to be based on one channel only with the diode board snapped off so it is much simpler than the universal power supply. Will this single unit power both sides of a stereo AlephJ or do I need two power supplies? There's only one shown so I made an assumption there that only one was required. I obviously don't need all those diodes with heatsinks right?
The Aleph J is a stereo as shown in the first build isn't it?
Next big question is how to wire up for 240volts.
I have bought the AS-4218 Antek torroidal as it says it is made to do either 120 or 240V input but there's obviously a different way to wire it.
Can anyone help me with that please?
Thanks guys this is a great forum.
Firstly it seems to be based on one channel only with the diode board snapped off so it is much simpler than the universal power supply. Will this single unit power both sides of a stereo AlephJ or do I need two power supplies? There's only one shown so I made an assumption there that only one was required. I obviously don't need all those diodes with heatsinks right?
The Aleph J is a stereo as shown in the first build isn't it?
Next big question is how to wire up for 240volts.
I have bought the AS-4218 Antek torroidal as it says it is made to do either 120 or 240V input but there's obviously a different way to wire it.
Can anyone help me with that please?
Thanks guys this is a great forum.
Post #1 shows the schematic for the power supply. For 240VAC, the primaries are connected in series along with a thermistor. With one transformer and one bipolar power supply board, both channels would be powered by the supply. The diode board is snapped off because 6L6 used diode bridges bolted to the bottom plate of the chassis. That can be seen in the pictures of the power supply.
The heat sinks that you have referenced will not work properly with the circuit boards as the heat sinks will need to be stacked vertically, so the transistors will not be able to be attached directly to both top and bottom heat sinks to distribute the heat evenly to them. It would work with two heat sinks per side if the heat sinks are divided vertically so that two transistors are attached directly to each heat sink.
The heat sinks that you have referenced will not work properly with the circuit boards as the heat sinks will need to be stacked vertically, so the transistors will not be able to be attached directly to both top and bottom heat sinks to distribute the heat evenly to them. It would work with two heat sinks per side if the heat sinks are divided vertically so that two transistors are attached directly to each heat sink.