G,
congratulations on your amplifier!
I'm dreaming also of having one warming our living room, as I now have a Firstwatt F4 and am really loving it! A power follower combined with a bit (SET/triodish) SIT spice has to be absolutely gorgeous for my taste. And 6 Tokins are resting in a drawer. (My smallest daughter now gets bigger and bigger, so that I can think of doing something like this. I also would love to have new (big) speakers, maybe open baffle or horns. As The Loudspeaker II (by Troels) passed the design committee's application (my wife), but she is open for "nicer" speakers, there is room for improving on this side as well. For any tips I'm very glad! I'm longing to have the last speaker.Yes, I know!)
G, did you use 2 Modushop cases? 5U500? This would also be my (lazy) way to go.
Thanks for posting it and the photos!
All the best,
Matthias
congratulations on your amplifier!
I'm dreaming also of having one warming our living room, as I now have a Firstwatt F4 and am really loving it! A power follower combined with a bit (SET/triodish) SIT spice has to be absolutely gorgeous for my taste. And 6 Tokins are resting in a drawer. (My smallest daughter now gets bigger and bigger, so that I can think of doing something like this. I also would love to have new (big) speakers, maybe open baffle or horns. As The Loudspeaker II (by Troels) passed the design committee's application (my wife), but she is open for "nicer" speakers, there is room for improving on this side as well. For any tips I'm very glad! I'm longing to have the last speaker.
G, did you use 2 Modushop cases? 5U500? This would also be my (lazy) way to go.
Thanks for posting it and the photos!
All the best,
Matthias
Hi Matthias,
I used some cases I bought locally. Size and weight of the heatsinks are very close to the Modushop 5U, with the major difference is that the Modushop 5U is two extrusions joined together (that's my understanding at least) and mine are a single peice.. In general the heat is controlled okay, but maybe not ideally. After 4 hours heat soaking the heatsinks do control it pretty well but unlike my other DIY efforts with multiple output devices, these do exhibit a hot spot directly behind the transistor. I would say by feel that hotspot is around 55C, where the ends of the heatsink feels closer to 50C. With such a large mass to heat up, the Vds on the SIT starts at about 35V and slowly falls to 33V over 3-4 hours, frankly I don't hear much difference over that time, but others might find something different.
Note: I mounted the SIT directly to the heatsink using only thermal compound to get as much heat out as possible.
The interior I would say is more concerning, the case has vents on the top and bottom but still it gets pretty toasty in there. I have thermal cutoff switch installed at 85C, and within my testing (max 4 hours) it hasn't cut off. I'm still considering adding an exhaust fan, but that's a bit of a project to get the case CNC'd for the fan and 12V inside the case. Also as I mentioned in a post above, I have fans on my big MOFO and I can hear them, and they are slightly annoying.
Attached is a pic of the two finished units to stimulate you!
G
I used some cases I bought locally. Size and weight of the heatsinks are very close to the Modushop 5U, with the major difference is that the Modushop 5U is two extrusions joined together (that's my understanding at least) and mine are a single peice.. In general the heat is controlled okay, but maybe not ideally. After 4 hours heat soaking the heatsinks do control it pretty well but unlike my other DIY efforts with multiple output devices, these do exhibit a hot spot directly behind the transistor. I would say by feel that hotspot is around 55C, where the ends of the heatsink feels closer to 50C. With such a large mass to heat up, the Vds on the SIT starts at about 35V and slowly falls to 33V over 3-4 hours, frankly I don't hear much difference over that time, but others might find something different.
Note: I mounted the SIT directly to the heatsink using only thermal compound to get as much heat out as possible.
The interior I would say is more concerning, the case has vents on the top and bottom but still it gets pretty toasty in there. I have thermal cutoff switch installed at 85C, and within my testing (max 4 hours) it hasn't cut off. I'm still considering adding an exhaust fan, but that's a bit of a project to get the case CNC'd for the fan and 12V inside the case. Also as I mentioned in a post above, I have fans on my big MOFO and I can hear them, and they are slightly annoying.
Attached is a pic of the two finished units to stimulate you!
G
Attachments
Nice looking cases.
To improve the passive cooling, you can add more cooling vents to the top and bottom panels. For the bottom panel, you can turn the chassis upside down and drill holes from the bottom. That way you do not have to remove any components. Just be careful to avoid drilling into any components or wiring. You can also drill the top panel. If you paint the holes they would not be too unsightly. Or you could do a Zen Mod mod by placing spaces between the top panel and chassis at the screw attachment points to allow a gap all around the perimeter of the top panel for the hot air to vent.
Another way to improve air flow is to the raise the chassis higher with taller feet, or place spacers under the feet.
Passive cooling is best if it can be done.
To improve the passive cooling, you can add more cooling vents to the top and bottom panels. For the bottom panel, you can turn the chassis upside down and drill holes from the bottom. That way you do not have to remove any components. Just be careful to avoid drilling into any components or wiring. You can also drill the top panel. If you paint the holes they would not be too unsightly. Or you could do a Zen Mod mod by placing spaces between the top panel and chassis at the screw attachment points to allow a gap all around the perimeter of the top panel for the hot air to vent.
Another way to improve air flow is to the raise the chassis higher with taller feet, or place spacers under the feet.
Passive cooling is best if it can be done.
Earlier in this thread Ben suggested a Noctua fan he was currently using. I used the same fan and initially added a voltage dropper plug from noctua to drop the speed and noise level of the already quiet fan. Around post #460 you will see forum members posting pics and suggestions for forced and passive cooling options. Post 462 shows a power supply and temp control board I used to drive the suggested fan after an internal temp of 39 degrees C is reached. My set up has the fan mounted directly above the supply capacitors blowing into the chassis. The temp sensor is mounted to the side of the capacitor at a point closest to the heat sink . Conveniently the temp controller displays the sensor temp at all times so a quick glance shows where things are at. As a secondary precaution I have the transformer and caps sitting on a silicone foam pad to lessen heat transfer. Also of note ... I settled on the 2.5a Iq rather than the 3a point....saving 30 watts of so of heat generation.
After 3 to 4 hrs listening sessions In winter months I was seeing internal temps around 41 deg C. Now in summer the temps reach 44 deg C. From 4ft away and purposefully listening for the fans they are not audible to me.
ZenMod's babysitter idea (fan in a box that the amp sits upon) may be even quieter due to its enclosed nature.
Ben displayed some good examples of passive cooling this beast earlier in this thread.
Good luck and congratulations on the build.
After 3 to 4 hrs listening sessions In winter months I was seeing internal temps around 41 deg C. Now in summer the temps reach 44 deg C. From 4ft away and purposefully listening for the fans they are not audible to me.
ZenMod's babysitter idea (fan in a box that the amp sits upon) may be even quieter due to its enclosed nature.
Ben displayed some good examples of passive cooling this beast earlier in this thread.
Good luck and congratulations on the build.
Citation,
Yes I saw that, I also use Noctua fans on my big MoFo, but I still hear them on quiet passages and I used an adjustable voltage regulator to undervolt them. I'll check out post 462 as I like the idea of the fans coming on after a ceratin temp is reached rather than running all the time.
I'll add that the first day of real listening was about 36C with little breeze, so my room rose to about 40C with those little heaters and my refusing to turn on the AC, mainly due to the AC raising the noise floor and I really wanted to listen critically. This last weekend it was (about 25C) and rainy with a nice breeze, and the temps on the heat sinks directly behind the SIT was still about 55C based on touch but the ends of the heat sink were likely closer to 45 as they felt warm but not hot in any way. This was after 12 hours of playing. Rainy day was nice to stay home and work on some projects and listen to music.
I'll run a thermocouple into the vent and do some temp monitoring, good idea thanks!
I'll also revisit ZM's babysitter, I did read that thread many years ago but had forgotten about it, now might be the perfect time to do that. It would be ideal if it would allow me to stack them as this would make the wife most happy if I could put them in the audio rack.
Ben,
I'm a bit aprehensive about drilling and painting holes in the top and bottom case, as I really don't think I can get paint to match the anodizing very well, and the wife is happier if I keep my projects looking more retail like. Generally she cares more about how they look than how they sound...
Thank you both for your helpful comments.
G
Yes I saw that, I also use Noctua fans on my big MoFo, but I still hear them on quiet passages and I used an adjustable voltage regulator to undervolt them. I'll check out post 462 as I like the idea of the fans coming on after a ceratin temp is reached rather than running all the time.
I'll add that the first day of real listening was about 36C with little breeze, so my room rose to about 40C with those little heaters and my refusing to turn on the AC, mainly due to the AC raising the noise floor and I really wanted to listen critically. This last weekend it was (about 25C) and rainy with a nice breeze, and the temps on the heat sinks directly behind the SIT was still about 55C based on touch but the ends of the heat sink were likely closer to 45 as they felt warm but not hot in any way. This was after 12 hours of playing. Rainy day was nice to stay home and work on some projects and listen to music.
I'll run a thermocouple into the vent and do some temp monitoring, good idea thanks!
I'll also revisit ZM's babysitter, I did read that thread many years ago but had forgotten about it, now might be the perfect time to do that. It would be ideal if it would allow me to stack them as this would make the wife most happy if I could put them in the audio rack.
Ben,
I'm a bit aprehensive about drilling and painting holes in the top and bottom case, as I really don't think I can get paint to match the anodizing very well, and the wife is happier if I keep my projects looking more retail like. Generally she cares more about how they look than how they sound...
Thank you both for your helpful comments.
G
One more thing to add. The finished amps in the picture have Nelson's FE2022 as the input stage, currently runnng SE, but I will likely change that to running balanced when I get the XLR connectors installed in the back of the chassis. I jumpered the spot on the board where the output cap goes since Ben's design already has a DC blocking cap on the input.
G
G
Citation/derekr
I looked it up and am using the Noctua NF-R8 redux-1200, this is only an 80mm fan so it could also be a bit noisier, but the heatsinks on the MoFo are 80mm blocks so I had to use this size. These are spec'd at 9.1dBa
Reading on the specs. these fans have SSO-bearing as the bearing type, whereas the faster fans have SSO2 bearings. I hear more bearing noise from them than air noise but both are detectable at my sitting position. Keep in mind the heat sinks and fans are fully exposed and it might be possible that the squre tube heat sink is amplifing the sound like a trumpet (this is just a guess).
G
I looked it up and am using the Noctua NF-R8 redux-1200, this is only an 80mm fan so it could also be a bit noisier, but the heatsinks on the MoFo are 80mm blocks so I had to use this size. These are spec'd at 9.1dBa
Reading on the specs. these fans have SSO-bearing as the bearing type, whereas the faster fans have SSO2 bearings. I hear more bearing noise from them than air noise but both are detectable at my sitting position. Keep in mind the heat sinks and fans are fully exposed and it might be possible that the squre tube heat sink is amplifing the sound like a trumpet (this is just a guess).
G
The fans I used were. Noctua NF-P12 redux-900, Ultra Quiet Silent Fan, 3-Pin, 900 RPM (120mm, Grey). As suggested by Ben.
Also rubber isolator pads to float the fans from the mounting surface
Noctua NA-SAVP1 chromax.Black, Anti-Vibration Pads for 120/140mm Noctua Fans (16-Pack, Black)
And voltage droppers - Noctua NA-SRC10, 3 Pin Low-Noise Adaptor Cables for PC fans (Black).
The rating I found was 12.6 db(A) without the voltage droppers.... Not certain what the ambient noise of your listening environment is. I found that if you got close and locked onto the fan noise and backed away it would be audible for a greater distance. However if one walked into an area where they were already on and wasn't looking for fan noise....I'm not sure you would pick it up.
I can't promise you won't hear anything, but I can say I'm very pleased with them.
Also rubber isolator pads to float the fans from the mounting surface
Noctua NA-SAVP1 chromax.Black, Anti-Vibration Pads for 120/140mm Noctua Fans (16-Pack, Black)
And voltage droppers - Noctua NA-SRC10, 3 Pin Low-Noise Adaptor Cables for PC fans (Black).
The rating I found was 12.6 db(A) without the voltage droppers.... Not certain what the ambient noise of your listening environment is. I found that if you got close and locked onto the fan noise and backed away it would be audible for a greater distance. However if one walked into an area where they were already on and wasn't looking for fan noise....I'm not sure you would pick it up.
I can't promise you won't hear anything, but I can say I'm very pleased with them.
Hi G, hi all others,
I'm referring to post #622.
I just finished this post, but my laptop shut down, because it didn't recognize the plugged in charger.
G, I really appreciate the long posting with the picture and all, this is very motivating! I especially like your case, as it is black and clear, it reminds me on the XA25.
I plan to start this year, and hope it'll be earlier.
First, if I'm disciplined enough, I'll measure the harmonic profile of different bias points, to try to find one which has much lower dissipation. Somehow I have a feeling that in the end it'll be the monoblocks anyway. And then for the hot months a different solution, and on top of this a ACA mini, for always having music in the room. For serious listening I'll switch to a serious amp, or let's say, a heavier amp.
At the moment my mind is occupied with new speakers. I haven't made up which type, but I'm curious about horns and open baffle. I want it more sensitive, so >> 90 dB/w/m, 96dB would be fine. And with a SET friendly impedance curve. My wife gave her OK for a big box. (Say Troels Gravesen The Loudspeaker II). So, if anybody has a recommendation or a advice where to look or what to read: I'm all ears!
Thank you, this is an amazing community!
Matthias
I'm referring to post #622.
I just finished this post, but my laptop shut down, because it didn't recognize the plugged in charger.
G, I really appreciate the long posting with the picture and all, this is very motivating! I especially like your case, as it is black and clear, it reminds me on the XA25.
I plan to start this year, and hope it'll be earlier.
First, if I'm disciplined enough, I'll measure the harmonic profile of different bias points, to try to find one which has much lower dissipation. Somehow I have a feeling that in the end it'll be the monoblocks anyway. And then for the hot months a different solution, and on top of this a ACA mini, for always having music in the room. For serious listening I'll switch to a serious amp, or let's say, a heavier amp.
At the moment my mind is occupied with new speakers. I haven't made up which type, but I'm curious about horns and open baffle. I want it more sensitive, so >> 90 dB/w/m, 96dB would be fine. And with a SET friendly impedance curve. My wife gave her OK for a big box. (Say Troels Gravesen The Loudspeaker II). So, if anybody has a recommendation or a advice where to look or what to read: I'm all ears!
Thank you, this is an amazing community!
Matthias
Ben,
You are right, I might move back to one of my other amps for the summer and keep these running when the warth can be appreciated, but you know with new toys it is hard to resist not playing with them.
Just from feeling the case, these 1 channel amps feel about the same as a 2 channel Aleph J or M2x. I can't campare the temps to the MoFo as it is actively cooled so might put out a lot of heat with cooler feeling heat sinks. Obviously
G
You are right, I might move back to one of my other amps for the summer and keep these running when the warth can be appreciated, but you know with new toys it is hard to resist not playing with them.
Just from feeling the case, these 1 channel amps feel about the same as a 2 channel Aleph J or M2x. I can't campare the temps to the MoFo as it is actively cooled so might put out a lot of heat with cooler feeling heat sinks. Obviously
G
Citation,
Excellent, I will try to use these inside the case. I'm less worried about the heat sink temps and more wanting to get the hot air out of the chassis, even in the cooler months I am guessing that it will be very toasty in there.
After several years of heavy usage in my home theater, the caps in my FW power supply on a Aleph J are breaking the plastic sleeves on the outside. I thik they are just deteriorating from the heat. Granted I have abused this great little amp, as it is in cabinet with limited airflow and is on for many - many hours. I remeber a few times when the 85C thermal cutt off switch shut them down, so I know it has see some good heat in there.
These higher power Class A beasts need room to breath and maybe a slow exhaust fan. This weekend I will rig up a thermal couple to monitor the temp at a resonable room temperture and make my decision on adding a fan or not.
G
Excellent, I will try to use these inside the case. I'm less worried about the heat sink temps and more wanting to get the hot air out of the chassis, even in the cooler months I am guessing that it will be very toasty in there.
After several years of heavy usage in my home theater, the caps in my FW power supply on a Aleph J are breaking the plastic sleeves on the outside. I thik they are just deteriorating from the heat. Granted I have abused this great little amp, as it is in cabinet with limited airflow and is on for many - many hours. I remeber a few times when the 85C thermal cutt off switch shut them down, so I know it has see some good heat in there.
These higher power Class A beasts need room to breath and maybe a slow exhaust fan. This weekend I will rig up a thermal couple to monitor the temp at a resonable room temperture and make my decision on adding a fan or not.
G
Hi Murdoc,
This is actually super simple to build as it is just an output stage, so very few part. You can check, double check, and triple check in just a few minutes.
As Ben wrote somewhere earlier, it is always a bit nervous to go through the power up procedure, but he has outlined it very well. This makes it safe even you made a little mistake in your parts placement.
For this much heat I can only recommend a monoblock setup. Of course this realy raises the cost, but if you want the higher power you need to pay for it. I beleive I could run it in my actively cooled MoFo chassis as a stereo amp, but would need to upgrade my fans, but this would make it even more noisier.
I have found this circuit to be very quiet, even with an ear pressed right up to the horn I can't hear a thing. It's a great design for those looking for a bit more power. You mentioned you would try different bias points, it's my understanding that this would give you less power output before clipping. This design has two pots, one for bias and one to adjust the SIT Vds. Going too much lower in bias will reduce the dissipation, but also the availible power. If going lower in power you have other options that might be less expensive. Take a look at Nelson's 2021 DIY Sony VFET part 1. It is a very similar circuit, but running at 36v and 1.6A, which is in the typical power range of FW's design language. It only dissipates ~57 watts, and could easily fit in a stereo chassis. I think the only other way to really deal with the heat is choke loading as Ben mentioned, and you can find some designs for that.
Keep in mind this design doesn't have a voltage amplification stage, that keep the cuircuit very simple but you might find you need to add a front end. Both Ben and I used the N. Pass FE 2022, as this slips in easily, running from the -V rail. I have really debated the need for a VAS as I typically don't listen loud and my speakers are pretty efficient.
Not to get too far off topic but I encourge you to try high efficient speakers, They have a different sound from normal commercial speakers, they tend to sound effortless in the music reproduction. I'm currently working to try to design a open baffle speaker around Lii Audio Fast-15. It's rated at 96dB/W/m but these efficiency numbers are not standardized so you need to be careful with seeing through the marketing. I will warn you, it is much harder to build a great speaker than a great amp. The tools and space need to measure a speaker, especially at low frequency is more difficult than using REW to measure a piece of electronics.
G
This is actually super simple to build as it is just an output stage, so very few part. You can check, double check, and triple check in just a few minutes.
As Ben wrote somewhere earlier, it is always a bit nervous to go through the power up procedure, but he has outlined it very well. This makes it safe even you made a little mistake in your parts placement.
For this much heat I can only recommend a monoblock setup. Of course this realy raises the cost, but if you want the higher power you need to pay for it. I beleive I could run it in my actively cooled MoFo chassis as a stereo amp, but would need to upgrade my fans, but this would make it even more noisier.
I have found this circuit to be very quiet, even with an ear pressed right up to the horn I can't hear a thing. It's a great design for those looking for a bit more power. You mentioned you would try different bias points, it's my understanding that this would give you less power output before clipping. This design has two pots, one for bias and one to adjust the SIT Vds. Going too much lower in bias will reduce the dissipation, but also the availible power. If going lower in power you have other options that might be less expensive. Take a look at Nelson's 2021 DIY Sony VFET part 1. It is a very similar circuit, but running at 36v and 1.6A, which is in the typical power range of FW's design language. It only dissipates ~57 watts, and could easily fit in a stereo chassis. I think the only other way to really deal with the heat is choke loading as Ben mentioned, and you can find some designs for that.
Keep in mind this design doesn't have a voltage amplification stage, that keep the cuircuit very simple but you might find you need to add a front end. Both Ben and I used the N. Pass FE 2022, as this slips in easily, running from the -V rail. I have really debated the need for a VAS as I typically don't listen loud and my speakers are pretty efficient.
Not to get too far off topic but I encourge you to try high efficient speakers, They have a different sound from normal commercial speakers, they tend to sound effortless in the music reproduction. I'm currently working to try to design a open baffle speaker around Lii Audio Fast-15. It's rated at 96dB/W/m but these efficiency numbers are not standardized so you need to be careful with seeing through the marketing. I will warn you, it is much harder to build a great speaker than a great amp. The tools and space need to measure a speaker, especially at low frequency is more difficult than using REW to measure a piece of electronics.
G
Hi G,
thanks again for your reply!
I appreciate your words and descriptions of ... everything.
I'm not nervous to build it, as it will not be the first thing on our kitchen table ;-) Step by step I'll test the modules, and then power it up. This will always be a intense moment, hoping that the magic smoke will stay in the output devices.
I was thinking in lines with this here: https://www.firstwatt.com/pdf/art_sweet_spot.pdf
Also Lhquam showed incredible measurements and mathematics with this Tokin's brother, the 2SK182.
I am curious having a follower powered by a SIT, single ended. Of cause this is the least efficient we can think of.
My speakers at the moment have real 90dB/W/m with a flat impedance curve. I wish to have "better" ones. (At the moment I have a AMT as a tweeter, 7" mids and 11" bass, all Eton. Not too shabby.)
I'll have a look at the VFET again, this is like watching a favorite movie again.
Keep us informed with your open baffle! The Lii drivers seem to be very interesting!
Enjoy the music,
Matthias
thanks again for your reply!
I appreciate your words and descriptions of ... everything.
I'm not nervous to build it, as it will not be the first thing on our kitchen table ;-) Step by step I'll test the modules, and then power it up. This will always be a intense moment, hoping that the magic smoke will stay in the output devices.
I was thinking in lines with this here: https://www.firstwatt.com/pdf/art_sweet_spot.pdf
Also Lhquam showed incredible measurements and mathematics with this Tokin's brother, the 2SK182.
I am curious having a follower powered by a SIT, single ended. Of cause this is the least efficient we can think of.
My speakers at the moment have real 90dB/W/m with a flat impedance curve. I wish to have "better" ones. (At the moment I have a AMT as a tweeter, 7" mids and 11" bass, all Eton. Not too shabby.)
I'll have a look at the VFET again, this is like watching a favorite movie again.
Keep us informed with your open baffle! The Lii drivers seem to be very interesting!
Enjoy the music,
Matthias
I intentionally built this amp with no front end. All of my follower amps have no built-in front end. This way I can have one preamp/gain stage that I can use for all of the amps. My current favorite is Nelson's DIY FE 2022 packaged as a free standing preamp. In my system it is my favorite, regardless of price.
As for Tokin SITs, they are high Wattage devices so I like to be able to take advantage of their power. With my sensitive speakers I do not need 50W, but need and want are two different things. The power is there. It is like wanting a V8 Cobra Jet or Hemi. Besides, there is nothing wrong with listening to the first Watt. It is actually a very good thing.
It seems that there may be a future First Watt amplifier that will be a Tokin follower, perhaps a Tokin mu follower follower SIT-5? Future FW?
As for Tokin SITs, they are high Wattage devices so I like to be able to take advantage of their power. With my sensitive speakers I do not need 50W, but need and want are two different things. The power is there. It is like wanting a V8 Cobra Jet or Hemi. Besides, there is nothing wrong with listening to the first Watt. It is actually a very good thing.
It seems that there may be a future First Watt amplifier that will be a Tokin follower, perhaps a Tokin mu follower follower SIT-5? Future FW?
Regarding more power than we need:
In the end it is like you said many posts ago: It is all about the sound we like. Your follower has very low distortion albeit being single ended. And, it is the first watt what counts, especially if we typically don't use more (of the amp's power).
I'm typically not listening loud, and with more sensitive speakers I even need less power. But when I first heard of designs with the SIT being followers, and on top single ended, I was sold!
This is all about enjoyment, not about rationality. This adds to our well being, to our health, physically and mentally.
In the end it is like you said many posts ago: It is all about the sound we like. Your follower has very low distortion albeit being single ended. And, it is the first watt what counts, especially if we typically don't use more (of the amp's power).
I'm typically not listening loud, and with more sensitive speakers I even need less power. But when I first heard of designs with the SIT being followers, and on top single ended, I was sold!
This is all about enjoyment, not about rationality. This adds to our well being, to our health, physically and mentally.