They quoted 4 weeks delivery time. To arrange all details and get commitment from all interested parties would take the whole upcoming week, I guess. Then I have to collect all the money, it will takes another week, Christmas in between. So I would estimate that I could place an order in second week of January, unless more time is needed.
Peter Daniel said:They quoted 4 weeks delivery time. To arrange all details and get commitment from all interested parties would take the whole upcoming week, I guess. Then I have to collect all the money, it will takes another week, Christmas in between. So I would estimate that I could place an order in second week of January, unless more time is needed.
Sounds great to me. I really like the idea of the 11" square cube. It just looks so simple, and a pair of them would be great. Thanks for taking the effort to organize this. How are you going to handle the payment? You mentioned that it might be possible for us to just pay r-theta ourselves, or are you just taking money orders in canadian funds yourself?
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Brian
Wraith said:
Put your name in the Wiki:
Here is the link to it:
http://www.diyaudio.com/wiki/index.php?page=R-theta+Heatsinks+for+Aleph-X
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Brian
Peter,
if you pay, will they charge 15% sales to the whole thing?
What about if each one of us pays rtheta directly with a CC? Since it was hinted that they would ship to individuals why not do that? It would be easier if the package gets damage to handle claims, etc. Have you proposed that to rT? We are guaranteeing a huge sale no matter how it's done and shipping must be calculated to individual destinations anyway.
I say that's the way to do it.
if you pay, will they charge 15% sales to the whole thing?
What about if each one of us pays rtheta directly with a CC? Since it was hinted that they would ship to individuals why not do that? It would be easier if the package gets damage to handle claims, etc. Have you proposed that to rT? We are guaranteeing a huge sale no matter how it's done and shipping must be calculated to individual destinations anyway.
I say that's the way to do it.
Speaking of heatsinks, I noticed that some people are planning on using 2 heatsinks per channel for monoblocks, and a few people are planning on using 1 heatsink per channel for a stereo chassis.
Has anyone taken the time to calculate the power rails and bias current for the correct heat dissipation for these two setups?
Here are the numbers that I have seen so far (correct me if I am wrong):
Grey's original schematic for 37.5w power:
2 x 15v x 4.5A = 135watts of dissipation per channel
Single heatsink capability:
25C / (.27 C/W) = ~90W of dissipation ability
Peter's design (15v rails, dropped from theoretical 20v from transformer, due to CRC filtering, and large current draw on transformer):
2 x 15v x 6A = 180W of dissipation for 2 channels, which hits the heatsinking ability exactly.
Are the above figures correct that I collected from various posts?
Here are my calculations as for the two configurations that I see likely:
1) for stereo chassis: 12v rails, around 3.75 A of bias current, giving 90W of dissipation per channel ~25W of power per channel
2) for monoblocks: instead of going for as high current like peter, I would lift the voltage up to 18v and use a total of 5A of bias current, giving around 60W of output per channel and 180W power dissipation.
Am I in the right ballpark? I am referencing Grey's calculations in the original Aleph-X thread.
--
Brian
Has anyone taken the time to calculate the power rails and bias current for the correct heat dissipation for these two setups?
Here are the numbers that I have seen so far (correct me if I am wrong):
Grey's original schematic for 37.5w power:
2 x 15v x 4.5A = 135watts of dissipation per channel
Single heatsink capability:
25C / (.27 C/W) = ~90W of dissipation ability
Peter's design (15v rails, dropped from theoretical 20v from transformer, due to CRC filtering, and large current draw on transformer):
2 x 15v x 6A = 180W of dissipation for 2 channels, which hits the heatsinking ability exactly.
Are the above figures correct that I collected from various posts?
Here are my calculations as for the two configurations that I see likely:
1) for stereo chassis: 12v rails, around 3.75 A of bias current, giving 90W of dissipation per channel ~25W of power per channel
2) for monoblocks: instead of going for as high current like peter, I would lift the voltage up to 18v and use a total of 5A of bias current, giving around 60W of output per channel and 180W power dissipation.
Am I in the right ballpark? I am referencing Grey's calculations in the original Aleph-X thread.
--
Brian
"Has anyone taken the time to calculate the power rails and bias current for the correct heat dissipation for these two setups?"
yes
"Grey's original schematic for 37.5w power:
2 x 15v x 4.5A = 135watts of dissipation per channel"
As I remembered correctly Grey was planning to use this with ribbon tweeter having 2 ohm imp. Under more friendly circumstances a total of 3 amp would be adequate so 90 W x chn at 15 V.
"Single heatsink capability:
25C / (.27 C/W) = ~90W of dissipation ability"
right
"Peter's design (15v rails, dropped from theoretical 20v from transformer, due to CRC filtering, and large current draw on transformer):
2 x 15v x 6A = 180W of dissipation for 2 channels, which hits the heatsinking ability exactly."
His rails dropped because of the way he wired his primaries.
"1) for stereo chassis: 12v rails, around 3.75 A of bias current, giving 90W of dissipation per channel ~25W of power per channel"
That's another way of getting 90W. a better way if you have a 12 Vac transformer IMHO.
"2) for monoblocks: instead of going for as high current like peter, I would lift the voltage up to 18v and use a total of 5A of bias current, giving around 60W of output per channel and 180W power dissipation."
I have sent this little gizmo to Chad for considaration, it's a universal output board, add 4 of these (or More) x chn to increase the output dissipation. I was shooting for a monoblock with a total of 180-200W dissipated x chn.
yes
"Grey's original schematic for 37.5w power:
2 x 15v x 4.5A = 135watts of dissipation per channel"
As I remembered correctly Grey was planning to use this with ribbon tweeter having 2 ohm imp. Under more friendly circumstances a total of 3 amp would be adequate so 90 W x chn at 15 V.
"Single heatsink capability:
25C / (.27 C/W) = ~90W of dissipation ability"
right
"Peter's design (15v rails, dropped from theoretical 20v from transformer, due to CRC filtering, and large current draw on transformer):
2 x 15v x 6A = 180W of dissipation for 2 channels, which hits the heatsinking ability exactly."
His rails dropped because of the way he wired his primaries.
"1) for stereo chassis: 12v rails, around 3.75 A of bias current, giving 90W of dissipation per channel ~25W of power per channel"
That's another way of getting 90W. a better way if you have a 12 Vac transformer IMHO.
"2) for monoblocks: instead of going for as high current like peter, I would lift the voltage up to 18v and use a total of 5A of bias current, giving around 60W of output per channel and 180W power dissipation."
I have sent this little gizmo to Chad for considaration, it's a universal output board, add 4 of these (or More) x chn to increase the output dissipation. I was shooting for a monoblock with a total of 180-200W dissipated x chn.
Attachments
grataku said:
IIRC, Peter's transformer was a 750VA +/- 40v transformer for the A75, which when he put the primaries in series, was +/- 20v 325VA transformer, due to having half the wire girth in the primary. I believe he stated that it was around 20v with no load, but dropped to 15v after load, and loss to CL-60 (or 40).
As for the stereo chassis version, if you had 15v rails, I would be worried that 3A of current wouldn't be enough, especially if you have 4 ohm speakers.
If 3A is fine for 15v rails, would 4.5A be fine for 20v rails?
Output boards look great! They should work good with the boards. I am planning on using 3 devices per bank for my Aleph-X monoblocks. My first version is only using 2 per bank, with my current heatsinks. I am aiming for 16v rails with 5A of total current.
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Brian
I think there is relation between rails voltage and minimum bias into 8 ohm. In other words for a given voltage you need certain amount of bias to get full use of this voltage into power. I remember that wuffwaff was showing some calculations. It is here: http://www.diyaudio.com/forums/showthread.php?s=&postid=89591#post89591
Peter and Brian,
remember that the trafo was designed to deliver 40V @ xAmps not 20V @ 2xAmps. So the voltage drop was due to Cu losses in both the primary and secondary. Iron may have also played a role since with a lower flux density you may be operating it in a very non linear region of the histerisis, but I don't remember how that looks.
I hope that is clearly and finally understood. If you buy the right trafo that will not happen
remember that the trafo was designed to deliver 40V @ xAmps not 20V @ 2xAmps. So the voltage drop was due to Cu losses in both the primary and secondary. Iron may have also played a role since with a lower flux density you may be operating it in a very non linear region of the histerisis, but I don't remember how that looks.
I hope that is clearly and finally understood. If you buy the right trafo that will not happen
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