It greatly depends upon the load. Mine is under 4ohm and this ideally means double the current and at least 20mF for the output cap. Actually that cap should be larger than 10k in any case as apart from determining the low frequency limit it may also form a resonant circuit with the coil.
Apart from these considerations the higher the current, the lower the thd.
I have the 300mm x 200mm Modushop heat sinks, one per channel, and they are able to dissipate 100W at 20C ambient with the heatsink hot but still cool enough that I can keep my hand on it indefinitely.
I have the 2SK180 mounted on a 2 1/2" x 2 1/2" x 1/4" x 6" long aluminum angle and I have ample cooling holes in the bottom and top plates alongside the heatsink.
Another factor is the maximum current rating of your choke.
If your speakers are 4 Ohm then 24V is feasible. I haven't done any testing at 4 Ohm so I don't have any idea as far as good operating points go. LTSpice simulations may give some indications of performance but the simulation results are only as good as the Tokin model used, and Tokins in real life have a lot of variation in their properties.
You may not get the maximum power output though as the peak to peak output voltage at onset of clipping cannot be higher than the supply voltage.
And if you have 8 Ohm speakers, then 24V is not good at all if you want to get the most power out of the device
It depends on what your goals are.
I have the 2SK180 mounted on a 2 1/2" x 2 1/2" x 1/4" x 6" long aluminum angle and I have ample cooling holes in the bottom and top plates alongside the heatsink.
Another factor is the maximum current rating of your choke.
If your speakers are 4 Ohm then 24V is feasible. I haven't done any testing at 4 Ohm so I don't have any idea as far as good operating points go. LTSpice simulations may give some indications of performance but the simulation results are only as good as the Tokin model used, and Tokins in real life have a lot of variation in their properties.
You may not get the maximum power output though as the peak to peak output voltage at onset of clipping cannot be higher than the supply voltage.
And if you have 8 Ohm speakers, then 24V is not good at all if you want to get the most power out of the device
It depends on what your goals are.
Thanks for pointing this out Ben and I hope you can get past this soon.
I haven't read through the bigger thread on the de-noiser in general but in the VRDN thread it became pretty clear that the problem was specifically with the TI LM337 (for myself included). Did others report instability issues with the STM version as well?
I am divided if I shod buy a Modushop 3 U chassis, ample sink there available @ € 155
or a chassis I have at hand. Really ugly . . . The big montrous transformer is from a build I once had of the Hiraga Le Montre. And I had 12 of those large cans in it too. In the middle large gapped chokes of 115 mH. Not the best iron though, used for 100Hz supply inductor.
But then I still need to buy 13cm heatsinks SK109 like the ironman uses . . . The sinks I have are 1 mm just too small for the large TO-BIGGIES of the 2SK180. Or maybe I can find a 3cmx5 T-plate. Then I am all set.
If I buy new sinks @ € 95, in the end there small price difference that makes the modu a nicer + better alternative.
or a chassis I have at hand. Really ugly . . . The big montrous transformer is from a build I once had of the Hiraga Le Montre. And I had 12 of those large cans in it too. In the middle large gapped chokes of 115 mH. Not the best iron though, used for 100Hz supply inductor.
But then I still need to buy 13cm heatsinks SK109 like the ironman uses . . . The sinks I have are 1 mm just too small for the large TO-BIGGIES of the 2SK180. Or maybe I can find a 3cmx5 T-plate. Then I am all set.
If I buy new sinks @ € 95, in the end there small price difference that makes the modu a nicer + better alternative.
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I received my heatsink today;
it's 500mm x 330mm x 50mm. Obtained for a very good price from ebay.
I've done lots of amps using conventional style chassis's but for this project I think I'll be different and go for a slim vertical tower type approach. The slot in the bottom will be perfect for an insert panel to hold the socketry.
it's 500mm x 330mm x 50mm. Obtained for a very good price from ebay.
I've done lots of amps using conventional style chassis's but for this project I think I'll be different and go for a slim vertical tower type approach. The slot in the bottom will be perfect for an insert panel to hold the socketry.
We seem to be on similar journeys Guglielmo, this project and Richard's MonoAmps.
Ray
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I plan to Ben. Also, with the efficiency of my speaker units I may not need the full 25W so maybe less heat generated - time will tell.
Yes. What a mass. scaring. A 4Kg transformer. 2 kg chokes each. 2caps @ >1 kg.
Additionally, the SK109/13cm 0,35 C/W heatsink weight 2.5 kg, that need to be added instead of the smaller ones on the picture giving 0,5C/W.
One advantage of this design is the flat top, easy to attach. And I can transpose the whole to a wooden frame later.
Compare: My F5 with 4 rows of Toshiba's 2SK175 has tall heatsinks, 6 such large cans. Similar transformer. Same bottom frame. I still can carry it.
But considering the work. I better buy a 2U 400mm Modu-case. The 2U/400mm deep with two sinks @ 0,67 each side will give in parallel, 0,33; per side. Just a common T-bar to connect them with the Tokin on it in the center would be good. The 12*50mm solid bar proposed somewhere is great too.
At <2 amp and 30 volts I should be happy with my 92 dB horns.
What are you guys using for a V+ supply?
I'm assuming I'll initially use a SMPS module to get the thing up and running but I then plan to use a pair of single-rail SLB Cap Multipliers.
I have the BiasV- sorted. I have several small, good quality, adjustable positive rail regulated power supplies in my spares box so I figure I'll just ground the positive output and use the modules ground connection for the BiasV-. If the bias supplies are adjustable I guess I can dispense with P1 and just increase R3 to around 4K7.
I'm keeping my fingers-crossed - the guy I bought the heatsink from thinks he may have another one the same stashed away - one per channel would be nice!
I'm assuming I'll initially use a SMPS module to get the thing up and running but I then plan to use a pair of single-rail SLB Cap Multipliers.
I have the BiasV- sorted. I have several small, good quality, adjustable positive rail regulated power supplies in my spares box so I figure I'll just ground the positive output and use the modules ground connection for the BiasV-. If the bias supplies are adjustable I guess I can dispense with P1 and just increase R3 to around 4K7.
I'm keeping my fingers-crossed - the guy I bought the heatsink from thinks he may have another one the same stashed away - one per channel would be nice!