| Leach clone, pretty good looking - Click HERE for Original Thread |
| JensRasmussen |
Are we talking super leach or extended Leach (that I use myself)?
I'll be happy to make a super leach layout, just tell me what transistors to use :)
\Jens |
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| Villaw |
I guess that the consensus as to the amp in need tilts towards the Leach super amp but that is up to everyone else. Personally I dont mind and would opt for anyone of the two as long as the power output is in the region of 200 -250 w or more at 8 ohms. Even though such power levels are overkills, nevertheless from my short experience, a high power amp is more versatile and is more likely to be useful for years to come than a smaller power one as evidenced by the Krells and the Levinsons of this world.
AS to the power transistor, I guess the choice is wide as long as it is readily available retaining the ability on the DIYer for stocking up should the need arise (more than likely)...
Do you have an estimate of a PCB cost of such a module with your markup? |
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| dherr555 |
| I wouldnt mind super amp pcb either.I have many of the transisitors that are on the original parts list So I would prefer them but I like to buy stuff that sits in the garage for years too.Check out this site prices look good for pcb's but not sure of quality, I am gonna do some of the low tim amp ,when I get time to draw them up. http://www.custompcb.com hey Jen looked at some of your web pages , Nice work.You are gonna give engineers a bad name.The ones I work with here are clueless and cant even dream about using tools.You do really good work. |
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| dherr555 |
Hello , I am thinking of purchasing transistors in quantity.Would anyone be interested in getting some from me afterwards.I will not mark them.
Mj15003 and mj15004 pretty expensive 03 are 2.13$ in qty of 100 and 04 are 1.84 each per 100 so i am not getting them
price price price
mj15031 . 68 mj15030 .75 mpsa06 .03
mpsa56 .04 2n5416 .56 2n3439 .58 |
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| acenovelty |
http://www.onsemi.com/site/products...MJ15003,00.html
MJ15003/4
$1.87 in hundred quantities. You can get 25 as samples.
Similar deals on other transistors. Oh yeah, these are the real Motorola parts, not some knock-off or fake product.
Hmm, ordered parts at 1:34 pm yesterday California time and they just arrived by FedEx at 9:02am today.
Prosit |
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| JensRasmussen |
Hello,
Is it time for a Super Leach new PCB design thread? :wiz:
I will gladly participate. :drink:
\Jens
:Popworm::Popworm::Popworm::Popworm::Popworm: |
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| still4given |
I think that would be great Jens. I am presently building one using TO-3 transistors. I would love to see a design that could utilize the flat packs.
Blessings, Terry |
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| jacco vermeulen |
I would love to have the Super Leach with a "Made in Danmark" sticker.
Either TO3, TO247, TO218 or MT200 works for me.
I can even have someone picking them up at your frontdoor.
(Maybe in time even a Threshold SA4 PCB, think of all the possibilities. Calm down,read a book :clown: )
BTW : Did you guys know that the Danish are the happiest people in the world, maybe that is why they are so nice ! |
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| Villaw |
| Very good. So I guess the die has been cast. Lets start. To attract more stray DIYers we need a fancy new thread any ideas? |
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| dherr555 |
| Do the large power supply have to be computer grade or will 10000uf 80v snap-in work okay ?And whats a good value for the caps.Would more then 10000uf better.I have seen many designs with more caps then two. |
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| JensRasmussen |
I'm sure that snap in is fine, I use them all the time
\Jens |
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| Villaw |
Jens,
Is the ordinary leach amp driver stage the same as the superamp one? If yes then we can start with easily the pcb I guess?? |
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| hienrich |
:angel:
it is really so rewarding to have been built a Leach.
my elder brother had just finished building one.
and still planning to built even more, I think for a 5.1 channel system
for his DVD.
actaully we have to thank Marshal Leach for his contributions:drink: :drink: :drink: :drink:
Jens, I'm hoping for more updates and more modifications about this
amp.
Just keep it up.....
and pls. post them on your site......
:wave2:
more power,
hienrich |
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| JensRasmussen |
Finally the boards arrived today
\Jens |
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| jacco vermeulen |
| Just a single word : WOW ! |
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| jaycee |
| I hope this isn't too off topic but what transistors are people using for the VAS/predriver stage of this amp ? What's the board designed to take ? |
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| EmZee |
one word
impressive !!!
:bigeyes: |
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| still4given |
I wannit, I wannit, I wannit, I wannit
saweeeet!:D |
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| JensRasmussen |
| quote: | Originally posted by jaycee
I hope this isn't too off topic but what transistors are people using for the VAS/predriver stage of this amp ? What's the board designed to take ? |
You can use BD139/140 for lower voltage models with rails below +- 40V and MJE340/350 for higher rails....
Transistors with similar pinout can also be used with caution
\Jens |
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| JensRasmussen |
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| JensRasmussen |
| quote: | Originally posted by JensRasmussen
You can use BD139/140 for lower voltage models with rails below +- 40V and MJE340/350 for higher rails....
Transistors with similar pinout can also be used with caution
\Jens |
I prefer the MJE340/350 devises because they have a higher voltage rating.
Of cause you need to run the amp at at least +- 50V rails so the BD types are not the best types to use as their rated CE voltage is 80 (If I remember correctly)
Please use thansistors with a rating of 120V or higher.
Sorry for the confusion
\Jens |
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| jaycee |
| OK. I had a feeling this would be the answer. However from SPICE sims im not convinced by the MJE parts. I'm currently looking at Japanese video driver transistors for this but models for them are few and far between. |
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| JensRasmussen |
I have had no problem using the MJE types...
Sure they are not the fastest in the world, but they work fine, and are easy to find almost all over the world.
If you find anything good, please post the info - thanks
\Jens |
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| LBHajdu |
Is it believed that replacing the MJE transistors with something else will yielded an auditable improvement with out causing any problems? If so, dose anybody have any recommendations (something form digikey or mouser)? I could not even begin to guess what would even work in the circuit. Given the low cost of medium power transistors, testing at least one alternate type seem like a very practical thing to do, especially if they have the same pin out. I have been told by many different people that Zetex makes very good sounding transistors. If anyone has a recommendation that looks reasonable and is available from digikey of mouser I would be willing to try it out. However, at the rate I’m making progress it’s going to take me about 6 months just to get to the point where I can try them out. Leach says, on his web site, that the second stage dose contribute the most to the sound as it is where most of the voltage gain is done.
Leve |
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| jleaman |
| When are these boards going to be available ? id like to buy a set of the smaller one's.. |
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| jacco vermeulen |
My favorite medium power transistors: 2SC2238 and 2SA968.
25 watts, 180 volts, 1.5 amp max, 70< Hfe < 240, 100 mHz. |
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| jacco vermeulen |
forgot the pic
regular : 160 volts
A type : 180 volts
B type : 200 volts
Pins: ECB, like the 340/350 |
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| JensRasmussen |
Front view, semi assembled
\Jens |
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| JensRasmussen |
| quote: | Originally posted by jleaman
When are these boards going to be available ? id like to buy a set of the smaller one's.. |
The Gerber files are on my website for free download....
I have no plans to offer the smaller boards for sale, I just made them for fun....
\Jens |
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| jacco vermeulen |
What about the 10 device boards?
We are supposed to sit here and drool ? |
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| JensRasmussen |
The 10 transistor version will be avalible when all has been tested.
Pricing is 250 dkkr / pcs. for the current batch.
This is roughly US$45
\Jens |
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| JensRasmussen |
\Jens |
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| jleaman |
| What about the other version.. the one with out all the transister's... I want to boards of that version.. |
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| JensRasmussen |
The Gerber files are on my website for free download....
I have no plans to offer the smaller boards for sale, I just made them for fun....
I have made a pre flight test on the 10 transistor version, and everything is working. Now I need to start shopping for components… 10 channels is a lot of soldering :) :) :)
\Jens |
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| jleaman |
| I'll solder some for free : O ) if i download your gerber files i can send them to a pc manufacture and they can print the boards for me right ? |
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| JensRasmussen |
Yes you can... be sure to tell them that you want atleast 2 oz of CU.
Maybe you could ask arround for others that might want some boards.
\Jens |
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| jleaman |
| I was also thinking that. I should. : O ) in canada and the us. |
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| jleaman |
jen's Can you tell me the board sizes of both board's please.
Also
Base Copper Thickness: oz
Plated Copper Thickness: oz
Inner Layer Thickness: oz
Minimum Space: in
Total Number of Holes:
Total Number of Hole Sizes:
_
what is Panelization is that so i can have a number of boards per sheet ?
If you want you can email me personally and we can talk.
Jason |
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| JensRasmussen |
| quote: | Originally posted by jleaman
jen's Can you tell me the board sizes of both board's please.
Also
Base Copper Thickness: oz
Plated Copper Thickness: oz
Inner Layer Thickness: oz
Minimum Space: in
Total Number of Holes:
Total Number of Hole Sizes:
_
what is Panelization is that so i can have a number of boards per sheet ?
If you want you can email me personally and we can talk.
Jason |
Base Copper Thickness: 2 oz
Plated Copper Thickness: 3 oz
Inner Layer Thickness: No inner layer oz
Minimum Space: 6/1000 in
Total Number of Holes: 443
Total Number of Hole Sizes: 13 (10 different)
Board is 108 x 214 mm = ???? in
PCB must be 2.4 mm in order to support the large caps
\Jens |
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| jleaman |
is that data for the 4 transister board or the 10 it looks a little small for the 10 ..
Jason |
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| JensRasmussen |
That is the 4 transistor version.
\Jens |
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| joan2 |
| quote: | Originally posted by JensRasmussen
Finally the boards arrived today
\Jens |
hi jens,
can you advise me thru email how i can get hold of a pair or two of these boards: tonyjtec@yahoo.com, thanks...
tony |
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| EFHeath |
I would also like to obtain a pair of these... I can't seem to find anything on the Delta Audio website about your selling them, but perhaps I'm just being obtuse?
EFHeath |
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| JensRasmussen |
Well I'm confident that the board works, so anyone that want boards should email me. The webpage has not been updated yet.
Price is 250 dkkr convert that into US$ and that will be the price.
Please add about 30 dkkr for skipping.
The board is 2.4 mm thick and has 3 oz CU.
The parts list is not finished yet, I will be working on that this weekend.
\Jens |
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| jleaman |
| Ok people i have the quote for the smaller version for 4 transistor Board. i'm going to start a new thread on this after permission from Jen's and other info Maybe i should go a canadian version of the 10 Transistor model ? Jens please email me or message me .. |
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| Villaw |
| count me in too for the big mamas.. |
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| jacco vermeulen |
There are plenty of those around where you live.
You dont need more ! |
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| JensRasmussen |
Hello all,
I have some extra boards from my own order. To get some money for heat sinks I have decided to sell one PCB + four 10.000µF 63V ELNA caps where two of these fit on the board.
The caps are leftovers from work, so I will charge nothing for them. The caps are not for sale separately, because I got a really got deal when I got them.
The price is fixed at US$ 45 + shipping for a set of caps + PCB.
Interested builders should post here; I have 10 boards for sale so whoever posts first will get boards.
\Jens |
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| jacco vermeulen |
2 boards please, Jens.
Where is the cashiers office ?
A suggestion where to get the MJL4281/4302 overhere i welcome. |
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| EFHeath |
| Just to confirm that I would like two boards. I have sent you e-mail as well. |
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| JensRasmussen |
Hello Jacco and EFHeath
Orders noted.... 6 boards to go.
I order output transistors at the local shop www.el-supply.dk
I'm putting together a list for them so I can get a price for a complete set of components from them, incl silicone insulators.
Please email me you address so I know where to send the boards.
The price US$ 45 is for ONE (1) board and four (4) caps. Please add shipping costs that I mail you......
\Jens |
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| Villaw |
I want two as well Jens
Thanks |
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| JensRasmussen |
Test results for today:
Rails not loaded = 63V
Rails loaded by 8 Ohm = 56V
Peak output 50V @ 1 kHz into 8 ohm = 156W
This was done using a 800VA transformer (The black thing in the background) The Dummyload is restive
\Jens |
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| JensRasmussen |
Test signal
20V/div
\Jens |
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| jacco vermeulen |
| quote: | Originally posted by JensRasmussen
a 800VA transformer (The black thing in the background) |
Ah, thats what it is !
2 *40 Vac ? |
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| JensRasmussen |
Hello,
Close.... 2 x 45 AC = +-63V
\Jens |
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| JensRasmussen |
Hello,
I just measured the power output into 4 ohm.
Vpeak @ 1 kHz is 47V with no clipping this is about 275W RMS into 4 ohm.
This fits very well with the 150W RMS into 8 ohm I measured yesterday.
More info here
\Jens |
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| JensRasmussen |
Hello,
All left over boards have now found new homes.
Thank you to those who support me by buying the extra boards
\Jens |
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| jacco vermeulen |
| OkiDoki, now it is time for a picture of Janni ! |
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| diyampss |
| quote: | Originally posted by JensRasmussen
Test results for today:
Rails not loaded = 63V
Rails loaded by 8 Ohm = 56V
Peak output 50V @ 1 kHz into 8 ohm = 156W
This was done using a 800VA transformer (The black thing in the background) The Dummyload is restive
\Jens |
Hi Jens,
Nice amp. How is the sound?
Joe |
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| AndrewT |
Hi
I have been following this thread for a while and awaited the results. I,m disappointed!
56Vrail to give 156w (50Vpk) is good for 2 pair of outputs but from 5 pair - seems to lose too much voltage somewhere.
BUT what happened to the PSU? 7v lost when loaded at 156w and 10v lost when loaded 275w and all from 800VA.
Something seriously amiss here? This transformer should be able to support at least 400w and maybe 500w at a push.
Can you give more detail of the PSU and wiring losses, caps etc. |
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| jacco vermeulen |
If you followed the thread on the Super Leach you may have read my suggestion for splitting powerlines for front end gain stages and the output stage.
This is the reason why.
Separate powerlines, use higher voltage for the front end, and the amplifier will deliver much more out of a 45 volt transformer.
45 volts rectified is 63 vdc, 50 volts out is a 13 volt drop.
156 and 275 are quite good numbers i think. |
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| JensRasmussen |
It's easy to split the supply to the input section, there is a resistor in series with that voltage :)
Rails loaded by 8 ohm are 56V @ 156W Output = 50V peak
Rails loaded by 4 ohm are 53V @ 275W Output = 47V peak
These numbers are based on RMS output power.
\Jens |
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| jacco vermeulen |
R1, R23, right ?
I did an amplifier from a magazine article once.
On a 30 VAC/300VA toroid and an added 9 VAC transformer for the front end it did 100 watt rms in 8, 175 in 4 Ohms.
(28.3 V and 26.5 V)
Mosfet amplifier, go figure. |
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| Villaw |
| quote: | Originally posted by jacco vermeulen
If you followed the thread on the Super Leach you may have read my suggestion for splitting powerlines for front end gain stages and the output stage.
This is the reason why.
Separate powerlines, use higher voltage for the front end, and the amplifier will deliver much more out of a 45 volt transformer.
45 volts rectified is 63 vdc, 50 volts out is a 13 volt drop.
156 and 275 are quite good numbers i think. |
How much higher front end voltage is recommended? and how much is the highest voltage we can go within the SOA for power transistors? |
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| jacco vermeulen |
I believe that for the Super Duper only something like 6 resistor values were altered, the rest were add-ons.
Everything above Q20 are extra's, the part recommendation list for Q1 till Q20 is the same.
I havent compared them exactly, so correct me if i am wrong.
Jens posted earlier that he did a Spice-sim. for 75 volts.
With the 10 devices Jens uses raising voltage isnt a problem, just needs a bigger heatsink.
At 350 volts theoretically you could build a 1500 watt amplifier with them.( just the thought)
I wasnt suggesting using a higher voltage on the output stage, merely pointing to the effect a single powersupply has.
Under load the voltage drops, so voltage drops on the front stage too.
With lower voltage on the front end it is not able to give the same voltage swing on the output stage and the amplifier reaches 1% distortion on a lower output level.
With a separate powersupply on the front end that can maintain a constant voltage of 63 volts i would expect the output stage to deliver a higher rms power level.
btw:
bigger toroids have a lower regulation factor, so voltage will drop less under load.
But any toroid can deliver twice the nominal output in peaks, an 800 VA model delivers 1600 if needed. |
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| JensRasmussen |
Hello,
I just reconfigured my test supply slightly.
Rail voltage at no load = +-93V
Rail voltage @ 8ohm = 76V, Vpeak = 70V => 315W into 8 ohms
Rail voltage @ 4ohm = 66V, Vpeak = 60V => 452W into 4 ohms
This was done with the same voltage on the input section as on the output section.
I have a vario transformer in front of the transformer, this makes the mains change more than it would be in a normal situation and therefor the supply has higher regulation than normal.
\Jens |
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| still4given |
| quote: | Originally posted by JensRasmussen
Hello,
I just reconfigured my test supply slightly.
Rail voltage at no load = +-93V
Rail voltage @ 8ohm = 76V, Vpeak = 70V => 315W into 8 ohms
Rail voltage @ 4ohm = 66V, Vpeak = 60V => 452W into 4 ohms
This was done with the same voltage on the input section as on the output section.
I have a vario transformer in front of the transformer, this makes the mains change more than it would be in a normal situation and therefor the supply has higher regulation than normal.
\Jens |
Wow, Jens,
You ran the rails up to 93VDC and no ill effects? Do you think it could live at that voltage? Aren't there some resistors who's value is determined by the projected voltage?
Sounds like you have one tough design working there.
Blessings, Terry |
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| JensRasmussen |
NO! do not run the amp at more than +-80V:att'n: :att'n: :att'n: for a longer period of time. I's better to get a transformer that has better regulation and use it at a lower voltage.
Yes you need to recalculate a resistorvalue by means of the formula give on Mr. Leach's hompage.
Again, do not run the amp at more than 80V!!!! :att'n: :att'n:
\Jens |
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| jacco vermeulen |
| quote: | Originally posted by JensRasmussen
Rail voltage @ 8ohm = 76V, Vpeak = 70V => 315W into 8 ohms
Rail voltage @ 4ohm = 66V, Vpeak = 60V => 452W into 4 ohms
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This was with the 2 times 10.000 uF on the board, Jens ?
Are you going to do some more dummy load testing?
I am curious what peak output in 4 Ohm is with 4 * 10.000. |
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| JensRasmussen |
| quote: | Originally posted by jacco vermeulen
This was with the 2 times 10.000 uF on the board, Jens ?
Are you going to do some more dummy load testing?
I am curious what peak output in 4 Ohm is with 4 * 10.000. |
Hello,
Yes this was done with the 2 x 10.000µF on board.
The peak output voltage will be about 6V below the railvoltage. the RMS power output will depend on the regulation of the transformer used.
I will try to make more measurements tonight.
\Jens |
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| Villaw |
Jens, apart from the measurements have you , by any chance, managed to arrange for a group buy of parts? or at least perhaps the semiconductors which sometimes are more difficult to trace?
Do you have any recommendations for heatsinks as to a supplier specific product? |
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| JensRasmussen |
Hello,
I just send the parts list to my local parts pusher here in Denmark.
They will look into the whole thing tomorrow.
I will post the result here.
If anybody is interested I can post the list, or I can order extra components.
I have not decided on heat sinks yet, but they will need to be in the region of 0.3 – 0.4 k/W
On my prototype amp I used a profile called S245
\Jens |
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| jacco vermeulen |
My two cents:
0.40 C/W with the MJL's Jens uses is good for real low impedance loads. That value is good for driving 3 Ohm hard on 45VAC mains.
I just bought 50 Toshiba devices, the ones they dont make anymore.
These have higher C/W than the MJL's so i will have to go for the 0.30 heatsink. |
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| WorkingAtHome |
| These aren;t more 2sc2565's are they? |
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| jacco vermeulen |
Yikes, NO !
These are the mommy's and daddy's of the 2SA1943/2SC5200.
In TO247/ TOP3L clothing, so they'll fit Jens's extended boards. |
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| WorkingAtHome |
| Wait, you mean these are 5200/1943s? They still make those. I am confused once again. Never mix babysitting and electronics. |
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| AndrewT |
Hi Jens
Any chance you can check the numbers without the variac in front of the PSU?
The outputs @ 4R & 8R from the loaded Vrail values quoted are pretty good.
It appears to be the PSU that is strangling the output. |
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| jacco vermeulen |
Bill, the 1943/5200 devices are the replacements for transistors as the 2SA1301, 2SA1302, 2SC3280, 2SC3281 and some other numbers.
The latter are the mommy and daddy's.
The 1943/5200 are the preferred now because Toshiba stopped production of the other ones years ago, and the world is flooding with Fakes.
The Chinese Shing Jing Co. makes a couple of those under the original number, dont know if they are considered counterfits.
I bought 2 tubes of the original guys.
Those devices have been used in so many top notch amplifiers in the past that i'll probably need a week to recollect all of them.
One that springs to my mind is the Luxman M07 from the 90s.
Around 125 watts in 8 Ohm , 6 of the Toshiba's per channel.
At that time a msrp of around $15.000.- (msrp in Europe, not US)
How old are your chickens? |
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| WorkingAtHome |
| 22 months. Rereading and it all makes sense. |
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| JensRasmussen |
| quote: | Originally posted by AndrewT
Hi Jens
Any chance you can check the numbers without the variac in front of the PSU?
The outputs @ 4R & 8R from the loaded Vrail values quoted are pretty good.
It appears to be the PSU that is strangling the output. |
No, I'm sorry, the vario transforer is needed in my current setup.
I will know more when I build the final powersupply.
\Jens |
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| rajeev luthra |
JensRasmussen ,
Please let me know of the protection test with input drive at supply +/-80v
Rajeev |
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| JensRasmussen |
This again will depend on the regulation of the transformer used.
I will test this when I get my transformers (+-75V unloaded 1000VA)
\Jens |
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| jacco vermeulen |
Party time !
Now its time for Santa to arrive. |
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| jacco vermeulen |
The extended leach boards have arrived. :smash:
Jens, these are the very best boards i have ever seen.
Anyone still waiting for your boards to arrive is in for a treat.
I do not desire to build another chassis for the Super Leach so i am going to build a universal one.
I decided to go full throttle on the extended leach.
Meaning:
i am placing the board on a heatsink, which will be mounted in a heatsink tunnel.
The tunnel will be U-shaped, welded from 10mm alloy plates.
The ampboard-heatsink module will slide in the U-channel, fastened on the sides with bolts.
The tunnel will have doubled dual-prop vents, two vents behind eachother, 4 vents per channel
dual-props you see with airplanes for noise reduction.
Cruiseships have Dutch Lips dual duct screws, for saving fuel and noise level reduction, like the Queen Elisabeth 2.
Doubling vents adds 3 dB, dualing two 80 mm 30 dB ventilators produce less noise than a single 120 mm type, with the same air flow volume.
Better even, the same flow through 0.44 of the 120mm area, which means 2.25 higher air speed.
Higher air speed means higher cooling rate.
I am aiming at a heatsink factor of 0.05.
Good enough for full class A with the extended leach, hopefully 200 watts.
The Super leach i am going to place on a similar heatsink, changing the two should be a matter of minutes.
I added a picture of the initial setup with one of your boards on top of two mirrored 250mm heatsinks.
The Orange caps are 100 Volt Siemens Long Lifes, the two small 50VA toroids for the front end powersupply.
The Blue's are Sprague 200 Volt models.
The pic is for a mono setup. |
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| JensRasmussen |
Hi Jacco,
I'm happy that you like the boards :)
.... and someone said the boards are big....... :)
Skype me, or contact me via MSN if you get the time
\Jens |
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| sajti |
| quote: | Originally posted by jacco vermeulen
The extended leach boards have arrived. :smash:
The tunnel will have doubled dual-prop vents, two vents behind eachother, 4 vents per channel
dual-props you see with airplanes for noise reduction.
Doubling vents adds 3 dB, dualing two 80 mm 30 dB ventilators produce less noise than a single 120 mm type, with the same air flow volume.
Better even, the same flow through 0.44 of the 120mm area, which means 2.25 higher air speed.
Higher air speed means higher cooling rate.
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My experience is that full speed fan is not necessary in most cases. Smaller speed is enough to cool down the heatsinks, and it results decreased noise. So, I recommend to use speed regulated fans.
sajti |
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| jacco vermeulen |
For the Super Leach i am aiming at +600 watts dissipation.
The vents will be speed regulated, probably intelligently temperature controlled.
I have to get rid of 10dB minimum, probably need to derate them to half speed.
Thank you for advising , Sajti.
Chassis size will be around 24' x 16' x 8' (wxdxh)
I said your boards are too small, Jens !
But they are ever so Cool.
(I have been holding them all afternoon, feeling the weight, looking at all the smooth trace curves.)
I really do not understand that someone would like closer nesting.
No doubt that these boards make the best Leach ever.
(those small Leach guys will undoubtebly be just as happy)
I'll get the headset out of the old suitcase.
(yesterday evening they made me install a new messenger version :xeye: ) |
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| sajti |
The half voltage is quite nice idea! Most of fans have no noise with half voltage. I have class A amplifier, which use fan cooling, with speed regulated circuit, I planned. This amplifier dissipates about 240W on a single 43cm long heatsink. And the fan never riched the maximum speed...
600W is serious amount of heat. I saw the cooling tunnel of the Crest CA12, with two 120mm fans run on full speed...
sajti |
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| jacco vermeulen |
Sajti,
any idea on the length of the tunnel on the Crest amplifier ?
I made an initial heat transfer calculation, dug up my old college
thermodynamica class books.
The entire chassis will be made of 10mm alloy, the duct will be thermally connected to the bottom of the chassis, with thermal grease.
the dual-prop vents will be contra-rotating, that should reduce noise and give better performance(i hope).
You do car racing?
thank you,
J. |
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| sajti |
The Crest has two 40cm long tunnels. The heatsinks filled up the whole 120x120mm cross section of the fan. It was really heavy!
I think that aluminium chassis would be better for cooling, due the alloy is not really good heat conductor. To connect the tunnel to the chassis is very good idea! I did it many times in my amplifiers...
sajti
Yes, I did some rallye racing, but it takes lot of money, and we didn't find enough sponsors to continue :( |
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| jacco vermeulen |
i decided to use the 300 watt/8 Giant2000 regulator for regulating the voltage on the front end of the extended Leach amp.
That amplifier used a stacked powersupply too, 15VDC on top of the 70Vdc main toroidal.
This circuit handled the voltage regulation for the entire front end including the driver section, the reason for using the BD712 that does well over 10 amps, 18 Max.
The 75 watt BD712 only has an Ft of 3 MHz.
I am going to swap that one for a faster Toshiba, or an IRF mosfet.
Basically i am going for at least 4 regulators for the front end.
For the regulator that handles the front end gain stages a 25 watt device will do as substitute for the BD712, 2SA968/2SC2238 or better.
For the regulator that does the driver stage the BD712 will be swapped for something with the same power capability or more.
Maybe a couple of them 2SA1302/3281 on a decent heatsink. |
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| jacco vermeulen |
| I just aquired nearly 20 of these 20VA toroids for a dollar and cents, those will be in series with the 50Vac from the main toroids. |
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| peranders |
Jens, I looked at your homepage and the picture of the step response. Did you compare the input signal also? Was it totally "clean" or did you have a small overshoot there also? What I ment was that your amp may be better than the picture wants to show. :nod: Otherwise :up:
http://www.delta-audio.com/Leach_Clone/Square.jpg |
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| Upupa Epops |
| To Jacco : Using of faster transistors is unneccessary, 'cos output of regulator is bypased by C 33,34 which are " batery " of energy. Faster transistors can make problems at this possition. |
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| jacco vermeulen |
Pavel,
you think the circuit is good as is, and good enough for regulating the Leach front stage?
I thought of emitting the caps, or placing a low value resistor between the emitter of T47 and the capacitors.
Thanks,
jacco. |
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| Upupa Epops |
| I mean that it will be OK. Inrush current is supressed by R 56, so you can't change anything :cool: . |
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| jacco vermeulen |
Actually UpuPMaPavel, now that you mentioned it.
I was also considering exchanging the entrance filter for more extensive R-C's, and reducing R56 to half or 1/4th and increasing C30 accordingly.
I am doubling the regulators for separate regulation of front end and driver stages anyway.
I'll take your advice and use the circuit as is.
Thank you for commenting,
J. |
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| JensRasmussen |
Hi all,
I have started work on a construction manual.
It's not done, but can be found here: http://www.delta-audio.com/temp_jen...ual_ver_0.2.pdf
I have only made the output transistor analyzes until now, but please comment on this if you have suggestions or need questions answered.
\Jens |
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