Seca build

phorizephorize
in DIY
Morning.

So I received my 20 watt seca boards from Colin with transformers and these bad boys:

https://uk.farnell.com/semikron/p3-180b/heat-sink-135x125x180mm/dp/1095607

I’ll be honest and say I was humbled that Colin gave them to me at the price he did. He could have charged far more. 

I’m looking for a steer on cases. My wife likes audio so I don’t have to work to hard to justify a new item,  but she has limits and I’m going to need to bank as much good will as possible for a future horn speaker build, so I need to end up with something that doesn’t end looking like my usual diy attempts-ie as if some mixed a load of components up in a bucket with some epoxy and just let it set.  I was looking at the Modi cases, but am struggling to picture how the end result will look with the semikrons. Another option would be to do mono blocks. Any suggestions?


Comments

  • AlanAlan
    This is most cool,I hope you enjoy the build! 

    I'm not sure about casing, but one idea would be a Modshop case (maybe 3 or 4u) and mounting those inside, with a heavily vented lid. That's how Colin configured the Tellurium Q Iridium 20 class A amplifier (there is a six moons review with pictures, also check the about us>Colin Wonfor on ABCaudio website).

    I think that may lead to fairly marginal cooling, but you would at least have a conventional looking box.

    WHICH IS SO BORING! You should totally mount those heatsinks on the outside of something so it looks totally cool! And it would run cooler. Colin did one that looked like a spaceship... Make a design statement with them!
  • DocfosterDocfoster
    phorize said:
    Morning.

    So I received my 20 watt seca boards from Colin with transformers and these bad boys:

    https://uk.farnell.com/semikron/p3-180b/heat-sink-135x125x180mm/dp/1095607

    I’ll be honest and say I was humbled that Colin gave them to me at the price he did. He could have charged far more. 

    I’m looking for a steer on cases. My wife likes audio so I don’t have to work to hard to justify a new item,  but she has limits and I’m going to need to bank as much good will as possible for a future horn speaker build, so I need to end up with something that doesn’t end looking like my usual diy attempts-ie as if some mixed a load of components up in a bucket with some epoxy and just let it set.  I was looking at the Modi cases, but am struggling to picture how the end result will look with the semikrons. Another option would be to do mono blocks. Any suggestions?


    Sondale made monoblocks with those boards and sinks (I think). Scroll down this page for piccies...
    http://www.audiochews.com/discussion/1608/building-colins-seca-kit/p3


  • uglymusicuglymusic
    edited June 2020
    phorize said:
    Morning.

    So I received my 20 watt seca boards from Colin with transformers and these bad boys:

    https://uk.farnell.com/semikron/p3-180b/heat-sink-135x125x180mm/dp/1095607

    I’ll be honest and say I was humbled that Colin gave them to me at the price he did. He could have charged far more. 

    I’m looking for a steer on cases. My wife likes audio so I don’t have to work to hard to justify a new item,  but she has limits and I’m going to need to bank as much good will as possible for a future horn speaker build, so I need to end up with something that doesn’t end looking like my usual diy attempts-ie as if some mixed a load of components up in a bucket with some epoxy and just let it set.  I was looking at the Modi cases, but am struggling to picture how the end result will look with the semikrons. Another option would be to do mono blocks. Any suggestions?



    My monoblocks follow the Sondale approach, but even more so, with bigger heatsinks because they have more heat to get rid of. I'm driving some fairly insensitive Royds and thought a few more watts might be a good thing.
    You probably don't want to see my cases - I was having the amps built on a budget and they're in mini-tower PC boxes!
  • phorizephorize
    uglymusic said:
    phorize said:
    Morning.

    So I received my 20 watt seca boards from Colin with transformers and these bad boys:

    https://uk.farnell.com/semikron/p3-180b/heat-sink-135x125x180mm/dp/1095607

    I’ll be honest and say I was humbled that Colin gave them to me at the price he did. He could have charged far more. 

    I’m looking for a steer on cases. My wife likes audio so I don’t have to work to hard to justify a new item,  but she has limits and I’m going to need to bank as much good will as possible for a future horn speaker build, so I need to end up with something that doesn’t end looking like my usual diy attempts-ie as if some mixed a load of components up in a bucket with some epoxy and just let it set.  I was looking at the Modi cases, but am struggling to picture how the end result will look with the semikrons. Another option would be to do mono blocks. Any suggestions?



    My monoblocks follow the Sondale approach, but even more so, with bigger heatsinks because they have more heat to get rid of. I'm driving some fairly insensitive Royds and thought a few more watts might be a good thing.
    You probably don't want to see my cases - I was having the amps built on a budget and they're in mini-tower PC boxes!
    Now I have to see them...
  • uglymusicuglymusic
    phorize said:
    uglymusic said:
    phorize said:
    Morning.

    So I received my 20 watt seca boards from Colin with transformers and these bad boys:

    https://uk.farnell.com/semikron/p3-180b/heat-sink-135x125x180mm/dp/1095607

    I’ll be honest and say I was humbled that Colin gave them to me at the price he did. He could have charged far more. 

    I’m looking for a steer on cases. My wife likes audio so I don’t have to work to hard to justify a new item,  but she has limits and I’m going to need to bank as much good will as possible for a future horn speaker build, so I need to end up with something that doesn’t end looking like my usual diy attempts-ie as if some mixed a load of components up in a bucket with some epoxy and just let it set.  I was looking at the Modi cases, but am struggling to picture how the end result will look with the semikrons. Another option would be to do mono blocks. Any suggestions?



    My monoblocks follow the Sondale approach, but even more so, with bigger heatsinks because they have more heat to get rid of. I'm driving some fairly insensitive Royds and thought a few more watts might be a good thing.
    You probably don't want to see my cases - I was having the amps built on a budget and they're in mini-tower PC boxes!
    Now I have to see them...

    No you don't! :-)
  • phorizephorize
    I’ve been looking at the heat dissipation properties of various heat sinks. The semikrons that I have are rated at 0.39 °C/W, which gives 39 c above ambient with 100 watts-59 c in a room at 20c.

    The modu case deluxe 5u is the case with is used for the ewa m100 and has heatsink rated at 0.28 C/W. Leading to 28c above ambient. I’m obviously missing something important as cols advice is keep the boards below 43 c or they will cut out. I’m very prepared to do a more wacky build if an external heatsink is a must, but I see a lot of pictures of cols seca in modu type cases so I’m intrigued as to what is going on. Obviously the fact that a heatsink is external will mean greater airflow. I do wonder if I can do something like place the semikrons inside the modu 5u, and use vented base and lid panels. If not I’ll take the opportunity to do something more unconventional.

    What do we think?
  • uglymusicuglymusic
    I can't help you with the numbers, but there are cases around that have integral external heatsinks, so if you look from the front of the case, you can't see the fins.
    I have no references, but they are around.
    I do know that at the time we (Colin) built my amps, the biggest issue was the size of the heatsinks and finding cases to accommodate them. We started with the heatsinks and worked backwards. But, as I said before, mine are 30 watts, so heat dissipation is a far bigger issue than with a 20 watt build.
    So, is the question (or one of the questions) here: how do I find a case that will accommodate Colin's recommended heatsinks?
  • AntiCrapAntiCrap
    I have worked with both and both are good companies.

    The heat sink can be allowed to go to 50C but I was worried about small kids finger getting burned.
    But use ceramic not SIL PAD insulators under the power devices.

  • AntiCrapAntiCrap
    phorize said:
    I’ve been looking at the heat dissipation properties of various heat sinks. The semikrons that I have are rated at 0.39 °C/W, which gives 39 c above ambient with 100 watts-59 c in a room at 20c.

    The modu case deluxe 5u is the case with is used for the ewa m100 and has heatsink rated at 0.28 C/W. Leading to 28c above ambient. I’m obviously missing something important as cols advice is keep the boards below 43 c or they will cut out. I’m very prepared to do a more wacky build if an external heatsink is a must, but I see a lot of pictures of cols seca in modu type cases so I’m intrigued as to what is going on. Obviously the fact that a heatsink is external will mean greater airflow. I do wonder if I can do something like place the semikrons inside the modu 5u, and use vented base and lid panels. If not I’ll take the opportunity to do something more unconventional.

    What do we think?

    In Dave's amp the heat sink are high on the back of the chassis so plenty of air flow.
    Also not on the design the thermistor this control the current and so when you set up set you max temp and it should stay close at all ambient temp, OK the power will reduce but the amp will survive.

  • uglymusicuglymusic
    AntiCrap said:
    phorize said:
    I’ve been looking at the heat dissipation properties of various heat sinks. The semikrons that I have are rated at 0.39 °C/W, which gives 39 c above ambient with 100 watts-59 c in a room at 20c.

    The modu case deluxe 5u is the case with is used for the ewa m100 and has heatsink rated at 0.28 C/W. Leading to 28c above ambient. I’m obviously missing something important as cols advice is keep the boards below 43 c or they will cut out. I’m very prepared to do a more wacky build if an external heatsink is a must, but I see a lot of pictures of cols seca in modu type cases so I’m intrigued as to what is going on. Obviously the fact that a heatsink is external will mean greater airflow. I do wonder if I can do something like place the semikrons inside the modu 5u, and use vented base and lid panels. If not I’ll take the opportunity to do something more unconventional.

    What do we think?

    In Dave's amp the heat sink are high on the back of the chassis so plenty of air flow.
    Also not on the design the thermistor this control the current and so when you set up set you max temp and it should stay close at all ambient temp, OK the power will reduce but the amp will survive.


    So, mine doesn't have a thermistor, just plenty of heat sink?
  • AlanAlan
    The other thing to note is the difference in topology.

    SECA get really, really hot because they run at maximum output all the time they are powered.

    EWA don't currently sell a SECA amplifier, they are all push/pull class A output (with SECA input driver stages) - kind of a hybridised approach. With dynamic biasing they can be much more efficient, so dissipate magnitudes less heat for greater output power.


  • phorizephorize
    uglymusic said:
    I can't help you with the numbers, but there are cases around that have integral external heatsinks, so if you look from the front of the case, you can't see the fins.
    I have no references, but they are around.
    I do know that at the time we (Colin) built my amps, the biggest issue was the size of the heatsinks and finding cases to accommodate them. We started with the heatsinks and worked backwards. But, as I said before, mine are 30 watts, so heat dissipation is a far bigger issue than with a 20 watt build.
    So, is the question (or one of the questions) here: how do I find a case that will accommodate Colin's recommended heatsinks?
    You mean all this time you were letting me a spout reams of rubbish and you knew the right question all along? ;) Erm, yd’s-that’s the question!
  • uglymusicuglymusic
    I like to cut to the chase :)
  • uglymusicuglymusic
    edited June 2020
    Alan said:
    The other thing to note is the difference in topology.

    SECA get really, really hot because they run at maximum output all the time they are powered.

    EWA don't currently sell a SECA amplifier, they are all push/pull class A output (with SECA input driver stages) - kind of a hybridised approach. With dynamic biasing they can be much more efficient, so dissipate magnitudes less heat for greater output power.



    Yep. A SECA amp is unique.
    If you have a 2 watt tube amp. No problem with heat dissipation. When you get to 20 or 30 watts, it's a challenge.
  • DocfosterDocfoster
    phorize said:
    I’ve been looking at the heat dissipation properties of various heat sinks. The semikrons that I have are rated at 0.39 °C/W, which gives 39 c above ambient with 100 watts-59 c in a room at 20c.

    The modu case deluxe 5u is the case with is used for the ewa m100 and has heatsink rated at 0.28 C/W. Leading to 28c above ambient. I’m obviously missing something important as cols advice is keep the boards below 43 c or they will cut out. I’m very prepared to do a more wacky build if an external heatsink is a must, but I see a lot of pictures of cols seca in modu type cases so I’m intrigued as to what is going on. Obviously the fact that a heatsink is external will mean greater airflow. I do wonder if I can do something like place the semikrons inside the modu 5u, and use vented base and lid panels. If not I’ll take the opportunity to do something more unconventional.

    What do we think?
    I used a Modushop case with integrated heat sinks in my SECA build.
    Absolutely fine.
    There's a list of the components in the first post here... http://www.audiochews.com/discussion/1666/bens-one4-wonfor-seca-build-ready-populated-boards/p1
    A few years old, so not sure if the links will still work.
  • phorizephorize
    Docfoster said:
    phorize said:
    I’ve been looking at the heat dissipation properties of various heat sinks. The semikrons that I have are rated at 0.39 °C/W, which gives 39 c above ambient with 100 watts-59 c in a room at 20c.

    The modu case deluxe 5u is the case with is used for the ewa m100 and has heatsink rated at 0.28 C/W. Leading to 28c above ambient. I’m obviously missing something important as cols advice is keep the boards below 43 c or they will cut out. I’m very prepared to do a more wacky build if an external heatsink is a must, but I see a lot of pictures of cols seca in modu type cases so I’m intrigued as to what is going on. Obviously the fact that a heatsink is external will mean greater airflow. I do wonder if I can do something like place the semikrons inside the modu 5u, and use vented base and lid panels. If not I’ll take the opportunity to do something more unconventional.

    What do we think?
    I used a Modushop case with integrated heat sinks in my SECA build.
    Absolutely fine.
    There's a list of the components in the first post here... http://www.audiochews.com/discussion/1666/bens-one4-wonfor-seca-build-ready-populated-boards/p1
    A few years old, so not sure if the links will still work.
    That’s interesting. Are you using the 20 watt version?
  • DocfosterDocfoster
    phorize said:
    Docfoster said:
    phorize said:
    I’ve been looking at the heat dissipation properties of various heat sinks. The semikrons that I have are rated at 0.39 °C/W, which gives 39 c above ambient with 100 watts-59 c in a room at 20c.

    The modu case deluxe 5u is the case with is used for the ewa m100 and has heatsink rated at 0.28 C/W. Leading to 28c above ambient. I’m obviously missing something important as cols advice is keep the boards below 43 c or they will cut out. I’m very prepared to do a more wacky build if an external heatsink is a must, but I see a lot of pictures of cols seca in modu type cases so I’m intrigued as to what is going on. Obviously the fact that a heatsink is external will mean greater airflow. I do wonder if I can do something like place the semikrons inside the modu 5u, and use vented base and lid panels. If not I’ll take the opportunity to do something more unconventional.

    What do we think?
    I used a Modushop case with integrated heat sinks in my SECA build.
    Absolutely fine.
    There's a list of the components in the first post here... http://www.audiochews.com/discussion/1666/bens-one4-wonfor-seca-build-ready-populated-boards/p1
    A few years old, so not sure if the links will still work.
    That’s interesting. Are you using the 20 watt version?
    Yes.
    Tho to confuse matters I think it's cranked up a bit more than that.
  • phorizephorize
    Docfoster said:
    phorize said:
    Docfoster said:
    phorize said:
    I’ve been looking at the heat dissipation properties of various heat sinks. The semikrons that I have are rated at 0.39 °C/W, which gives 39 c above ambient with 100 watts-59 c in a room at 20c.

    The modu case deluxe 5u is the case with is used for the ewa m100 and has heatsink rated at 0.28 C/W. Leading to 28c above ambient. I’m obviously missing something important as cols advice is keep the boards below 43 c or they will cut out. I’m very prepared to do a more wacky build if an external heatsink is a must, but I see a lot of pictures of cols seca in modu type cases so I’m intrigued as to what is going on. Obviously the fact that a heatsink is external will mean greater airflow. I do wonder if I can do something like place the semikrons inside the modu 5u, and use vented base and lid panels. If not I’ll take the opportunity to do something more unconventional.

    What do we think?
    I used a Modushop case with integrated heat sinks in my SECA build.
    Absolutely fine.
    There's a list of the components in the first post here... http://www.audiochews.com/discussion/1666/bens-one4-wonfor-seca-build-ready-populated-boards/p1
    A few years old, so not sure if the links will still work.
    That’s interesting. Are you using the 20 watt version?
    Yes.
    Tho to confuse matters I think it's cranked up a bit more than that.
    Good to know. 
  • phorizephorize
    edited June 2020
    AntiCrap said:
    The heat sink can be allowed to go to 50C but I was worried about small kids finger getting burned.
    Thanks for the thought. I think heat is a feature not a bug in that respect. Is there anything you can do to heat up my new sme arm?-at the moment I’m to scared to take it out of the box, too many bad memories about the fate of my up until then mint Garrard 401 that  my 3 year son discovered after we
    moved house. I knew that children couldn’t just rotate on the spot so I thought my eyes were deceiving me at first...
  • AntiCrapAntiCrap
    uglymusic said:
    AntiCrap said:
    phorize said:
    I’ve been looking at the heat dissipation properties of various heat sinks. The semikrons that I have are rated at 0.39 °C/W, which gives 39 c above ambient with 100 watts-59 c in a room at 20c.

    The modu case deluxe 5u is the case with is used for the ewa m100 and has heatsink rated at 0.28 C/W. Leading to 28c above ambient. I’m obviously missing something important as cols advice is keep the boards below 43 c or they will cut out. I’m very prepared to do a more wacky build if an external heatsink is a must, but I see a lot of pictures of cols seca in modu type cases so I’m intrigued as to what is going on. Obviously the fact that a heatsink is external will mean greater airflow. I do wonder if I can do something like place the semikrons inside the modu 5u, and use vented base and lid panels. If not I’ll take the opportunity to do something more unconventional.

    What do we think?

    In Dave's amp the heat sink are high on the back of the chassis so plenty of air flow.
    Also not on the design the thermistor this control the current and so when you set up set you max temp and it should stay close at all ambient temp, OK the power will reduce but the amp will survive.


    So, mine doesn't have a thermistor, just plenty of heat sink?
    It does and you use ice cream to keep it cool so Sam said.
  • phorizephorize
    https://diyaudiostore.com/collections/deluxe/products/deluxe-5u-ultimate-amplifier-chassis?variant=12212123204

    I’m eyeing this chassis. It’s the hifi2000 one but with everything predrilled and they do a nice back panel kit to go with it. Not the cheapest or most avant garde option but factoring for the cost of
    decent metal working tools that I’ll only use once seems like a relatively affordable way of getting the show on the road. Mind you, I’m noticing that I’m desensitising to cost at the moment. Someone mentioned that I could use tad 2002 compression drivers in a horn/bass reflex speaker that I’m thinking about. How I laughed, until I caught myself thinking through the maths and finding myself doing some highly motivated reasoning in favour. Time to disconnect the internet I think. 
  • uglymusicuglymusic
    AntiCrap said:
    uglymusic said:
    AntiCrap said:
    phorize said:
    I’ve been looking at the heat dissipation properties of various heat sinks. The semikrons that I have are rated at 0.39 °C/W, which gives 39 c above ambient with 100 watts-59 c in a room at 20c.

    The modu case deluxe 5u is the case with is used for the ewa m100 and has heatsink rated at 0.28 C/W. Leading to 28c above ambient. I’m obviously missing something important as cols advice is keep the boards below 43 c or they will cut out. I’m very prepared to do a more wacky build if an external heatsink is a must, but I see a lot of pictures of cols seca in modu type cases so I’m intrigued as to what is going on. Obviously the fact that a heatsink is external will mean greater airflow. I do wonder if I can do something like place the semikrons inside the modu 5u, and use vented base and lid panels. If not I’ll take the opportunity to do something more unconventional.

    What do we think?

    In Dave's amp the heat sink are high on the back of the chassis so plenty of air flow.
    Also not on the design the thermistor this control the current and so when you set up set you max temp and it should stay close at all ambient temp, OK the power will reduce but the amp will survive.


    So, mine doesn't have a thermistor, just plenty of heat sink?
    It does and you use ice cream to keep it cool so Sam said.

    Any excuse for ice cream, Col :)
  • uglymusicuglymusic
    phorize said:
    https://diyaudiostore.com/collections/deluxe/products/deluxe-5u-ultimate-amplifier-chassis?variant=12212123204

    I’m eyeing this chassis. It’s the hifi2000 one but with everything predrilled and they do a nice back panel kit to go with it. Not the cheapest or most avant garde option but factoring for the cost of
    decent metal working tools that I’ll only use once seems like a relatively affordable way of getting the show on the road. Mind you, I’m noticing that I’m desensitising to cost at the moment. Someone mentioned that I could use tad 2002 compression drivers in a horn/bass reflex speaker that I’m thinking about. How I laughed, until I caught myself thinking through the maths and finding myself doing some highly motivated reasoning in favour. Time to disconnect the internet I think. 

    That's a cool box!
  • DocfosterDocfoster
    phorize said:
    https://diyaudiostore.com/collections/deluxe/products/deluxe-5u-ultimate-amplifier-chassis?variant=12212123204

    I’m eyeing this chassis. It’s the hifi2000 one but with everything predrilled and they do a nice back panel kit to go with it. Not the cheapest or most avant garde option but factoring for the cost of
    decent metal working tools that I’ll only use once seems like a relatively affordable way of getting the show on the road. Mind you, I’m noticing that I’m desensitising to cost at the moment. Someone mentioned that I could use tad 2002 compression drivers in a horn/bass reflex speaker that I’m thinking about. How I laughed, until I caught myself thinking through the maths and finding myself doing some highly motivated reasoning in favour. Time to disconnect the internet I think. 
    Easy to drill into the case and heatsinks with a standard hand drill and metal bit. I didn't have any other specific tools or previous metal work experience.
    But if you don't have a drill already, maybe pre-drilled the better option. (Though you may need to drill need to drill the aluminium plates on the amp boards...?)
  • cj66cj66
    A little left field but.....

    Get a nice front panel from the likes of hifi2000 and attach a smaller diy/repurposed "box" behind it so the box and heat sink(s) are no wider than the front panel. The box can then be whatever depth you require to house all the electronics.
  • Marra49Marra49
    That's what I did with my build. 4U front from Modushop and heatsinks from GD Rectifiers. Similar heatsinks are available from Birmingham Alluminium.

    https://www.bal-group.com/heatsink_detail/104
  • phorizephorize
    Now mono blocks with rear facing semikrons in these hd cases would be positively bad ass, so to speak:

  • uglymusicuglymusic
    phorize said:
    Now mono blocks with rear facing semikrons in these hd cases would be positively bad ass, so to speak:


    They're also cool ;-)
  • AntiCrapAntiCrap
    http://www.audiochews.com/discussion/2440/the-long-time-coming-seca-16w-40w-pcb#latest
  • ianian
    Phorize; I’m going to be making a SECA with Colin’s latest boards.   I’m aiming for the full 40wpc   :D.    My plan for mono block enclosures is to first buy the heatsinks (from BAL) and then have a local metal fabricator (there are lots near me) build a chassis incorporating one heatsink as a side panel.   An option to explore?

    BTW, I also have a horn speaker project in my future.   I have a pair of JBL 2450 SL that have had Truextent Be diaphragms fitted.   I’m assured by a horn expert who I know that they will be almost as good as the top TAD CDs but at considerably lower cost.   So just expensive rather than very expensive . . . 
Sign In or Register to comment.