Hi there!
I have for a while tought about building a Aleph 30, and would like some input about how they sound, some building tips etc.
I'll order the pcb's from diyamps.com once I'm sure this is the right project. I don't have the cash to build all the amps I come across, so I want to build a good one.
How do I bias it up, btw? And how big heatsinks do I need for some serious bias? Any recommended suppliers?
Regards,
EsE
I have for a while tought about building a Aleph 30, and would like some input about how they sound, some building tips etc.
I'll order the pcb's from diyamps.com once I'm sure this is the right project. I don't have the cash to build all the amps I come across, so I want to build a good one.
How do I bias it up, btw? And how big heatsinks do I need for some serious bias? Any recommended suppliers?
Regards,
EsE
EsE,
First The Aleph 30 draws 200 watts
the transfo is 600VA or more 2*18 volts giving +-25volts
Well you have to dissipate 100 watts by side {by channel}
and the 2Amps bias is fixed!
** At 25/30 degree C over ambient temp that gives:
coeff for 30 deg = about 1.33 {see chart}
the MF35-151.5 from Conrad is: 350 mm long or 13.7"
151.5 mm height or 5.96"
0.21 C/Watt for 80 °C rise
==> 0.21 * 1.33 = 0.28 C/W
so for 30 degrees rise ==> 30 / 0.28 C/W = 107 watts
for each heatsink in a rapid calculus... I would say right on target
take a look at this info:
http://www.conradheatsinks.com/technical-details.html
Good luck with this project.
Alain.
First The Aleph 30 draws 200 watts
the transfo is 600VA or more 2*18 volts giving +-25volts
Well you have to dissipate 100 watts by side {by channel}
and the 2Amps bias is fixed!
** At 25/30 degree C over ambient temp that gives:
coeff for 30 deg = about 1.33 {see chart}
the MF35-151.5 from Conrad is: 350 mm long or 13.7"
151.5 mm height or 5.96"
0.21 C/Watt for 80 °C rise
==> 0.21 * 1.33 = 0.28 C/W
so for 30 degrees rise ==> 30 / 0.28 C/W = 107 watts
for each heatsink in a rapid calculus... I would say right on target
take a look at this info:
http://www.conradheatsinks.com/technical-details.html
Good luck with this project.
Alain.
I recently built an Aleph30. I found that I needed a a transformer of 21 to 22 volts to get 25VDC rails.
The MF350-151.5 heatsinks are perfect for an Aleph30. The operating temperature is exactly on spec for what Nelson has described when built with the factory rail and bias settings. Alan's calculations are correct for the Conrad heatsink. I'd consider modeling or experimenting with the transformer voltage you actually select.
Think about a largest VA rating for your transformer. I've experimented with different VA ratings. Currently I'm using a 700VA trafo with 22.5vac with a small amout of R in a CRC PSU. The trafo get very hot. There are more standard trafo's available with 45vac secondaries, and could be wired to 220vac for use in 120vac countaries to get close to 22.5vac for the PSU.
Here's a link to my amp for reference:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=70622
Good luck,
-David
The MF350-151.5 heatsinks are perfect for an Aleph30. The operating temperature is exactly on spec for what Nelson has described when built with the factory rail and bias settings. Alan's calculations are correct for the Conrad heatsink. I'd consider modeling or experimenting with the transformer voltage you actually select.
Think about a largest VA rating for your transformer. I've experimented with different VA ratings. Currently I'm using a 700VA trafo with 22.5vac with a small amout of R in a CRC PSU. The trafo get very hot. There are more standard trafo's available with 45vac secondaries, and could be wired to 220vac for use in 120vac countaries to get close to 22.5vac for the PSU.
Here's a link to my amp for reference:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=70622
Good luck,
-David
Ok, thanks!
I live in Norway, so 230V is my mains current, actually..
Most people agree that Alpeph's sound great, but what would you compare it to?
The heatsinks look allright, but can I make the rest of the chassis in wood when it's running at 70 degrees? I'm not to good with metal, and I don't have the tools if I'm willing to try.
And at last, what kind of power supply will make the best sound?
I'd love some schemes..
EsE
I live in Norway, so 230V is my mains current, actually..
Most people agree that Alpeph's sound great, but what would you compare it to?
The heatsinks look allright, but can I make the rest of the chassis in wood when it's running at 70 degrees? I'm not to good with metal, and I don't have the tools if I'm willing to try.
And at last, what kind of power supply will make the best sound?
I'd love some schemes..
EsE
I'm currently building the aleph 1.2 monoblocks and for me main issues with this amp is getting the heatsinks and the metalwork done. For the Aleph 30, these issues are not that difficult. It all depends on how much money you want to spend. However, I may have input.
Heatsinks: I bought mine from fisher. They have a sales contact office in Norway, and they can help you find what you need. I had to spend 8500 kr for 4 heatsinks - but they dissipate 1000 w (all 4 together).
A good starting point would be fisher SK56 (200x400x40mm)
If not you could try clofis - a dutch vendor who sells good quality heatsinks (seifert), and they aren't expensive. This is probably the way to go.
Or...you could go the easy way and buy a casing from one of several vendors.
I have bought my parts from www.RT-audio.nl. He can also help with casing and/or heatsinks. Send him an email.
If you need any more information, send me a PM and I'll be glad to help you. I am however a newbee to DIY myself so I don't think I will be of much assistance with regard to tech stuff.
But when it comes to vendors of this and that...just ask!
Heatsinks: I bought mine from fisher. They have a sales contact office in Norway, and they can help you find what you need. I had to spend 8500 kr for 4 heatsinks - but they dissipate 1000 w (all 4 together).
A good starting point would be fisher SK56 (200x400x40mm)
If not you could try clofis - a dutch vendor who sells good quality heatsinks (seifert), and they aren't expensive. This is probably the way to go.
Or...you could go the easy way and buy a casing from one of several vendors.
I have bought my parts from www.RT-audio.nl. He can also help with casing and/or heatsinks. Send him an email.
If you need any more information, send me a PM and I'll be glad to help you. I am however a newbee to DIY myself so I don't think I will be of much assistance with regard to tech stuff.
But when it comes to vendors of this and that...just ask!
EsE said:
I believe wood would deteriorate over time coming in contact with that much heat. A fire hazzard might be a consideration, depending on your design. You still have some machining to do even with a wood chassis. The heatsinks need to be drilled and tapped for mounting the mosfets and angle brackets to a wood base.
Lots of folks have had aluminum panels cut by a shop and attached together by using aluminum angle or rectangular bar stock. You could have www.frontpanelexpress.com machine a back panel for you with the connector holes cut and labeled.
Surprising how more the chassis costs than the amp internals.
Good luck on your build,
-David
Dear David DW 8083,
Well, I have nearly no experience with metal. But the tools are simple and cheap, and the box is simple to build. My plan is as follows:
You could start with two of those Conrad heatsinks. Their baseplates are 8mm thick and can easily be drilled for either 3 or 4 mm metric bolts. Purchase the correctly sized drills (Aus$ 2.20)and taps (AUS$8.00)from your local engineering shop. A nice T-handle for the taps would cost about AUS$12 ... more or less. A nice counter-sink AUS$ 8.00.
Use the heatsinks as the sides of the box. Then get some second hand plate aluminium for the top, bottom (perhaps thicker for which ever piece you are using to mount the transformers on)and the back of the box ... maybe 3 mm thick and perhaps a nice thicker piece for the front plate.
A satisfactory bench drill press costs only about AUS$60. A few pieces of angle aluminium for the edges. Build it, screw it together, put on the top and you have a wonderful rectangular prism!!!
Polish up the aluminium, perhaps a clear spray on finish or better some anodizing, put it out of the way, because your wife really doesn't really want to see it ... she wants to see the pre-amp with nice knobs and a few LED's ...
Some nice rubber feet, perhaps with a touch of gold.
Search this website for Mark Finnis ... he has some simple techniques to build a box for an Aleph 4 and 5.
Problem solved ... or at least that is the plan.
Good Luck and have lots of fun.
Regards,
George.
Hi George,
My chassis is similar to Mark's. I had www.frontpanelexpress.com make a 1.5mm sluminum plate based on a CAD drawing from their free CAD tool. Next I had a local sheetmetal shop bend the design into a box on a sheetmetal brake.
I used 1/4-20 inch hexhead cap screws a 1/4 inch long to fasten the Conrad Heatsinks to the chassis. Using round head or hexcap screws eliminated the need for countersinking.
Here's a link the the final chassis and some work in progress pictures.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=70622
-David
My chassis is similar to Mark's. I had www.frontpanelexpress.com make a 1.5mm sluminum plate based on a CAD drawing from their free CAD tool. Next I had a local sheetmetal shop bend the design into a box on a sheetmetal brake.
I used 1/4-20 inch hexhead cap screws a 1/4 inch long to fasten the Conrad Heatsinks to the chassis. Using round head or hexcap screws eliminated the need for countersinking.
Here's a link the the final chassis and some work in progress pictures.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=70622
-David
Banned
Joined 2002
EsE said:
I'd like to note for this project. You will need to buy / find. Heat sinks that are going to disapate all this heat.
Heat sink's and power transformers are the most costly thing's the rest is fairly cheap. If you need any help with the aleph boards please let me know i have built up alot of them.
EsE and DW8083
Dear EsE
My posting was meant for you, EsE, in an effort to encourage you to get started and not worry too much about "working with metal"!!! Also, you can cut thinner aluminium sheet with your tungsten-carbide tipped "wood" blade on a bench saw. For thicker stuff, I would still pop in a cut-off disc and use that, and lots of eye and ear protection ... and thick leather gardening gloves.
Sorry David, DW8083! I got the addressee wrong. It is clear that you have done a fine job, and your gear will look lovely in comparison with my hodge-podge.
Oh well, I was just trying to encourage people, as does Nelson Pass, to "just build something" rather than analyzing too much.
Regards,
George.
Dear EsE
My posting was meant for you, EsE, in an effort to encourage you to get started and not worry too much about "working with metal"!!! Also, you can cut thinner aluminium sheet with your tungsten-carbide tipped "wood" blade on a bench saw. For thicker stuff, I would still pop in a cut-off disc and use that, and lots of eye and ear protection ... and thick leather gardening gloves.
Sorry David, DW8083! I got the addressee wrong. It is clear that you have done a fine job, and your gear will look lovely in comparison with my hodge-podge.
Oh well, I was just trying to encourage people, as does Nelson Pass, to "just build something" rather than analyzing too much.
Regards,
George.
Thanks George for the kind words, I really love listening to my amp.
BTW, I'm finally getting around building a nice case for my BOSOZ pre-amp. It could have easily won 1st prize for ugliest box on this forum!... but is sounded incredible. So good infact I did not want to touch it, and used it as is for almost 2 years this way.
This is a great hobby, and when your eyes are closed and listening to the beautiful gift of music that Nelson has so graciously given us, the appearance does not really matter in the end. Just as long as the amp is safe to operate.
-David
BTW, I'm finally getting around building a nice case for my BOSOZ pre-amp. It could have easily won 1st prize for ugliest box on this forum!... but is sounded incredible. So good infact I did not want to touch it, and used it as is for almost 2 years this way.
This is a great hobby, and when your eyes are closed and listening to the beautiful gift of music that Nelson has so graciously given us, the appearance does not really matter in the end. Just as long as the amp is safe to operate.
-David
Ok, I might have a big power amp I can take the heatsinks from. It also has one/two big transformers, is there any way I can change the voltage out of them so they fit the Aleph? I haven't started ordering parts, but if I get this amp I have the two most expensive parts! If I get this amp and the parts are good enough, I can go for some quality components inside the amp!
If I get this amp and the parts are good enough, I can go for some quality components inside the amp!
EsE
You are from a cold place . . .
I simplify "one" heatsink as a heater rated at 0.28degC/W.
The heater gives temp rise of 0.28degC per 1 watt, as an example 14degC per 50 watts . . . By the way, the total heat energy (watts) is from the transistors fixed on the heater.
Maybe, I am making you further confused . . . ?
Regards
You are from a cold place . . .
I simplify "one" heatsink as a heater rated at 0.28degC/W.
The heater gives temp rise of 0.28degC per 1 watt, as an example 14degC per 50 watts . . . By the way, the total heat energy (watts) is from the transistors fixed on the heater.
Maybe, I am making you further confused . . . ?
Regards
jh6you said:EsE
You are from a cold place . . .
I simplify "one" heatsink as a heater rated at 0.28degC/W.
The heater gives temp rise of 0.28degC per 1 watt, as an example 14degC per 50 watts . . . By the way, the total heat energy (watts) is from the transistors fixed on the heater.
Maybe, I am making you further confused . . . ?
Regards
Ok, I think I understand! So I need one heatsink rated at 0.28 for one channel? And can I in any way find out if the heatsinks in this amp I'm talking about is big enough? Maybe I just need to take the measurments and see how similar sinks rate..
EsE said:
Hi EsE,
You will need one heatsink per channel with less than .30c/w rating for an Aleph30.
Alain's heatsink calculations at the top of the thread are correct. A common mistake people make is to forget to correct the manufacturere's c/w rating for ambient room temperature. I used a correction factor of 1.4 to be more conservative.
-David
EsE said:
Alain gave you a good calc.
As far as I know, Aleph 30 has 50V difference between + and - rail, and the bias current is about 1.6A. Therefore, the total power dissipation of MOSFETs per channel is about 1.6*50=80W. I think if the 0.28degC/W is correct rate, the temp rise of the heat sink will be about 23degC above room temp, or more as some part of the heatsinks are to be burried into the closed chassis. I recommend you to take time and try to find a little bit bigger size, considering potential adjustment of higher bias current for better (?) sound.
Good luck,
Re: Frontpanelexpress in Europe
Great! I'll download the software and see how it works.
Another heatsink question: I'll need two sinks with around 0.28 C/W rating. Can I use four sinks with around 0.50 C/W instead?
I haven't looked to closely on the methods of calculating this, I have you guys!
Thanks for all your help so far! I really think I can do this now!
uli said:
Great! I'll download the software and see how it works.
Another heatsink question: I'll need two sinks with around 0.28 C/W rating. Can I use four sinks with around 0.50 C/W instead?
I haven't looked to closely on the methods of calculating this, I have you guys!
Thanks for all your help so far! I really think I can do this now!
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.