Great, I'm glad you got it sorted out
And thanks for your help in that.
I might have thrown the device into the trash bin, if it were not for your comments.
Before any attempt to tune for the sweet spot, some THD measurement attached, when power was at 1W and 8W respectively.
THD was 1.0% at 1W and 2.3% at 8W, probably not great but not too bad as a start. Unfortunately the QA400 doesn't like my 6 year old notebook and keep crashing, so I'm not able to start my sweet spot search mission yet.
THD was 1.0% at 1W and 2.3% at 8W, probably not great but not too bad as a start. Unfortunately the QA400 doesn't like my 6 year old notebook and keep crashing, so I'm not able to start my sweet spot search mission yet.
Attachments
Woow that very high bias and your heat sinks are giants !!!
My biger heat sinks i find in town have weight ~ 33 kg | 70 lb
two pieces together good start & useful
to experimenting no compromise amps.
What about 30 or 50 watts rms single-ended champions sit's amplifiers ?
Kind regards
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The 1W curve shows the k2/k3 relation mostly preferred. K2 about 12-14dB higher than k3. Of course you will get THD down to around 0.5% or even lower by reducing k2.
But the "sweet" spot is a matter of taste. K3 or k2 dominance is both possible and have its own advantages concerning the sound.
But I suppose you know all this.....
Christoph you are building a 1000watt SE?
And also, @TIM,: The QA400 work well.
Hav'a nice Sunday Gentlemen. And Please Mr Pass, pity, give us your goodies with the part 2, The summer is coming now and I not afford the CSX1 yet because you promise soon the part two.
Thanks in advance.
And also, @TIM,: The QA400 work well.
Hav'a nice Sunday Gentlemen. And Please Mr Pass, pity, give us your goodies with the part 2, The summer is coming now and I not afford the CSX1 yet because you promise soon the part two.
Thanks in advance.
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But I suppose you know all this.....
Hi generg,
Actually I didn't, but I do now, so thanks for the sharing.
@Soundhappy, it seems you have finally collected some working 182ES, and we look forward to your monster single-ended amplifier (mine will be kept at 10W max, the Asian summer are too hot for anything more)
@dady, thanks and I managed to solve the QA400 crashing issue, so having some sweet spot finding fun now, and I realized why Michael called this a black art, it's not as simple as I had thought ...
Yesterday my friend Juan Antonio, jama, was hardly sharing with me the curves that he is making with the Michael's tool-tracer, He discovered that the industrial pieces have extremely different curves making almost impossible to get a good pair of them between the quantity we are collecting together and making a common pool with more pieces with the object to match some of them.
And the most important that he found was the similarities that have the Sony (Acroman parts) taking then randomly, showed incredible parallelism between them.
And the most important that he found was the similarities that have the Sony (Acroman parts) taking then randomly, showed incredible parallelism between them.
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Hi Esteban,
I was afraid to hear this..... Today my Chinese friend is coming and brings me four 2SK182ES bought at taobao.
All is possible...fakes or four very different parts.
Concerning the SK180 your friend seems to be a lucky guy, my parts I got from Acronman were very different.
When I built Luminaria I took the parts showing the most most parallel behaviour and the one with the higher transconductance got a small source resistor.
So the gain got fairly equal.
I was afraid to hear this..... Today my Chinese friend is coming and brings me four 2SK182ES bought at taobao.
All is possible...fakes or four very different parts.
Concerning the SK180 your friend seems to be a lucky guy, my parts I got from Acronman were very different.
When I built Luminaria I took the parts showing the most most parallel behaviour and the one with the higher transconductance got a small source resistor.
So the gain got fairly equal.
Yes generg I had check 22 THF51 and none equal. Only some slightly similar. Because of that I am modifying tracer tool to check them into operation point (25V Vds and 4 A, 12Wrms and 65V of PS) and so I hope to select good pairs. I have checked four 2Sk180C too and they are very similar (only one it is a little different others).
I have gone through 15 2SK182ES from Taobao, I think they're all authentic, but the failure rate was 40% (6 out of 15 were bad).
I also notice that the refurbished ones (rust removed and electroplated to look nice and shiny) are more prone to failure, probably the refurbishing process could damage the SITs.
Sweet spot?
THD 0.25% @1W is the lowest I could make, but it has 2 drawbacks:
... I think final decision will be determined by the ears, but not the measurement equipment.
THD 0.25% @1W is the lowest I could make, but it has 2 drawbacks:
- The THD@1W is the lowest when Id=1.3A, which limits the usable power at 8R to be around 5W;
- Third harmonic dominant to second harmonic @1W;
... I think final decision will be determined by the ears, but not the measurement equipment.Attachments
@ cwtim01
look at the SIT-1 distortion pictures of Nelson in the owners manual at First Watt…
as far as I understand he allows at 1W adjustment from 0.25%, maybe k3 dominant, to 1.8%, maybe more k2 dominant.
And some people in the reviews liked the k3 dominant others the k2 dominant sound.
Ears are decisive instrument……
http://www.firstwatt.com/pdf/prod_sit1_man.pdf
look at the SIT-1 distortion pictures of Nelson in the owners manual at First Watt…
as far as I understand he allows at 1W adjustment from 0.25%, maybe k3 dominant, to 1.8%, maybe more k2 dominant.
And some people in the reviews liked the k3 dominant others the k2 dominant sound.
Ears are decisive instrument……
http://www.firstwatt.com/pdf/prod_sit1_man.pdf
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