Hi guys,
We might finally be as hot as Greece, we broke 30C today 🙂
There are slight differences in Vf for red, some are GaP and most new ones are higher eff AlInGaP. I do not think a few 100mV is going to make a whole lot of difference, esp with a servo balancing it out.
It is an interesting design. many tubes are natural duals, not to say the trans-conductance's match well.
Valery how well do tubes match? 🙂 I know little of tubes other than they glow and get damn hot. Winter design 🙂
I see they put on MELF hermetic diode packages for you too 😱
Thimos, I think it would be a good experiment to adj the heater supply, to see how low you can run it before it affects performance.
We might finally be as hot as Greece, we broke 30C today 🙂
There are slight differences in Vf for red, some are GaP and most new ones are higher eff AlInGaP. I do not think a few 100mV is going to make a whole lot of difference, esp with a servo balancing it out.
It is an interesting design. many tubes are natural duals, not to say the trans-conductance's match well.
Valery how well do tubes match? 🙂 I know little of tubes other than they glow and get damn hot. Winter design 🙂
I see they put on MELF hermetic diode packages for you too 😱
Thimos, I think it would be a good experiment to adj the heater supply, to see how low you can run it before it affects performance.
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Up to now i used down to 5v as i have many unused smps.
As for the tube matching...
I have this RSD ecc82 NOS good matching.
I bought new Electroharmonics ecc82 that they don't match at all.
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I have just finished a project which used the 1980 Maplin disco amplifier as its base.
I just used 2 output transistors instead of 4 as I only needed 100 watts RMS.
It uses newer easier to get hold of transistors but I kept the TO3 format for the output transistors. This makes the mounting bracket fun to make getting all the holes exactly right.
The amp sounds very good into a pair of Fane 12-250TC's.
The picture is the first one I designed.
The second one I designed has a DC servo too for good DC tracking.
I just used 2 output transistors instead of 4 as I only needed 100 watts RMS.
It uses newer easier to get hold of transistors but I kept the TO3 format for the output transistors. This makes the mounting bracket fun to make getting all the holes exactly right.
The amp sounds very good into a pair of Fane 12-250TC's.
The picture is the first one I designed.
The second one I designed has a DC servo too for good DC tracking.
An externally hosted image should be here but it was not working when we last tested it.
The triodes within the tube are normally matched well enough.
I have 1 tube out of 6 that causes significant disbalance of the front-end, all the rest are no problem at all.
Some stores offer the tubes with the triodes already matched. I buy them with no matching but always order some extra quantity to choose from.
Those small tubes are not too hot - heat dissipation is less than 2W per tube, not enough for being useful in winter 😛
TubSumo 2sk146GR
Another variant.
Stand alone test.
Another variant.
Stand alone test.
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Definitely not class-A weather then 🙂 Parts of UK had 30+ last weekend, its 27
today, the dilemma is whether to risk soldering in shorts!
Holy cow Valery, it is like I am looking thru my spy glass, doing inspection 🙂
After I spoke I did download a Tung-sol datasheet to find out what Valery said, 2w heater = no big deal 🙂
another hot one today too, 30C plus the humidity factor, they say 40C, but that is the city smog factor too. thank god I live in the country side. we need the hot weather to make up for the long cool/wet spring. heat, sun, water = grow
After I spoke I did download a Tung-sol datasheet to find out what Valery said, 2w heater = no big deal 🙂
another hot one today too, 30C plus the humidity factor, they say 40C, but that is the city smog factor too. thank god I live in the country side. we need the hot weather to make up for the long cool/wet spring. heat, sun, water = grow
Thimios - great job!
This one deserves a compartment 😉
Tubsumo front-end + NS Modular OPS = the finest amplifier 🙂
I strongly recommend this combination as a basis for the highest definition home system.
One of my favorite ones
Thimios, and just to make sure that everybody understand, it is Deg C, not American Farenheit !!😀 I sometimes get it 36 deg C 21:00 at night and it feels like it is getting worse, toooo much for me !!😱
Thanks Valery, agree.Thimios - great job!
This one deserves a compartment 😉
Tubsumo front-end + NS Modular OPS = the finest amplifier 🙂
I strongly recommend this combination as a basis for the highest definition home system.
One of my favorite ones
Thank you and Jeff who give me the opportunity to have such a nice amplifier.
Thank you evanc, for the heatshinks.
Thank you all for your generosity!
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Thimios,
You inspired me. I populated this pair of NS-OPS this morning. I need to drill some heatsinks and then I can begin testing. I built the little VFA IPS boards a while back but didn't have an OPS to test them.
Thanks Valery and Jeff for this nice design. I hope to have some results in a couple days.
You inspired me. I populated this pair of NS-OPS this morning. I need to drill some heatsinks and then I can begin testing. I built the little VFA IPS boards a while back but didn't have an OPS to test them.
Thanks Valery and Jeff for this nice design. I hope to have some results in a couple days.
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Hi Terry, good to hear from you!
The boards look great, looking forward to seeing the test results
