| 回覆 (1027): 湯瑪士的第二次 |
This thai guy has also done a 10KHz square wave test on the same james opt. I don't think there is big difference between his and my curves.
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it is slightly better but not much. as i said, scope trace is useful to locate abnormality but does not tell much about other things. |
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drwkng
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10-06-23
12:39:13
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| 回覆 (1026): 湯瑪士的第二次 |
Yes, the test has been repeated on both channels and the results are quite similar. The strange things might have been caused by the poor quality of my sig gen and and probes etc.
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but yours seem o.k. so that's why i'm a bit puzzled.
But I am a bit more comfortable when i see the figures of the haslingaudio topped with the other brands opts.
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hmm.. you mean the lundhal and SJS. it is quite interesting that the behaviour of these two and the chinese cow are quite different than james,
silk and yours as well. they all have dominant 2nd order distortion with decreasing higher order distortion. whereas yours, james and silk have higher 3rd order than 2nd order.
with a competent engineer mdlover doing the test with me, these considerations could hardly be omitted. Nothing has been done to any other parts of the amp.
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what i meant was that the reflected impedance of the opt will affect the behaviour. have you measured the dynamic operating conditions to ensure the reflected impedance are all in the same ball park.
well.. the next thing would be to measure the low end response^-^ |
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drwkng
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10-06-23
12:35:05
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| 回覆 (1026): 湯瑪士的第二次 |
drwkng,
http://www.sacthailand.com/Transformer_TestOutput.html
This thai guy has also done a 10KHz square wave test on the same james opt. I don't think there is big difference between his and my curves. |
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ThomasC2
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10-06-23
12:25:51
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| 回覆 (1025): 湯瑪士的第二次 |
drwkng,
'''''Thomas, i salute your perseverance. '''
that's nothing when compared with yours in your creation of your products and, in fact, opt winding is real fun.
"""""the scope shots are a bit strange for james. at 10khz, it should be more decent. i supposed you have ensured that it is not amp casusing the problem and repeated the test on both left and right channels. """"""
Yes, the test has been repeated on both channels and the results are quite similar. The strange things might have been caused by the poor quality of my sig gen and and probes etc.
""""the distortion is a bit disappointing. what power output level are you measuring the amp? """""
It was measured at 1W output. yes, when compared with the Haslingaudio's 300B SET with James opt, my figures are disappointing. But I am a bit more comfortable when i see the figures of the haslingaudio topped with the other brands opts.
""""before the tests have you ensured that amp is running at the same conditions. as you know, the distortion can easily be accounted for by the different operating conditions of the 300B amp.""""
with a competent engineer mdlover doing the test with me, these considerations could hardly be omitted. Nothing has been done to any other parts of the amp.
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ThomasC2
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10-06-23
12:16:51
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| 回覆 (1024): 湯瑪士的第二次 |
Thomas, i salute your perseverance.
a few questions.
the scope shots are a bit strange for james. at 10khz, it should be more decent. i supposed you have ensured that it is not amp casusing the problem and repeated the test on both left and right channels.
the distortion is a bit disappointing. what power output level are you measuring the amp?
before the tests have you ensured that amp is running at the same conditions. as you know, the distortion can easily be accounted for by the different operating conditions of the 300B amp. |
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drwkng
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10-06-23
11:15:57
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| 回覆 (1023): 湯瑪士的第二次 |
10KHz again. Impressive, isn't it?
____________________________
Certainly yes for tube power, but then ss can do this with ease.
Good work!
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limage
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10-06-23
09:27:24
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feikeung
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10-06-23
03:33:16
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| 回覆 (1021): 湯瑪士的第二次 |
My Opt no. 1 disappointed me with its sharp rolloff at high frequency. According to the below figures , this Opt no. 2 appears to have greatly improved in this respect.
Frequency / Output level on 4 Ohm load
20 KHz / 2.2V
10 KHz / 2.05V
5 KHz / 2V
1 KHz / 2V
500 Hz / 1.99V
100 Hz / 2V
20Hz / 1.96V
Special thanks to c-hing mdlover who did the FFT spectrum for me. |
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ThomasC2
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10-06-22
23:57:03
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| 回覆 (1020): 湯瑪士的第一次 |
| To make sure that the setup was working properly and the results are reliable, another opt wound by a famous chinese si-fu lying around was connected to the amp and tested under same conditions. |
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ThomasC2
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10-06-22
23:43:22
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ThomasC2
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10-06-22
23:37:11
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| 回覆 (1018): 湯瑪士的第一次 |
| As requested by drwkng, FFT distortion spectrum has also been done. Let's look at that of James first. Haslingaudio's 300B amp working with James opt shows a incredibly low THD of 0.0288%. Distortion of my 300B amp equiped with James opt (probably a cheaper version) is much higher. |
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ThomasC2
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10-06-22
23:32:47
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ThomasC2
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10-06-22
23:23:22
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ThomasC2
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10-06-22
23:21:01
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ThomasC2
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10-06-22
23:19:15
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| 回覆 (1014): 湯瑪士的第一次 |
| just got an engineer who volunteered to do the FFT spectrum for me soon. will post the result if it is not too 失禮。 |
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ThomasC2
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10-05-20
22:39:08
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Vash
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10-05-20
22:36:41
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accphoto
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10-05-20
22:07:34
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| 回覆 (1012): 湯瑪士的第一次 |
thomas, forget about engineers. most people don't really like amps produced by them anyway^-^.
when i talked about spectrum, i'm thinking more like using FFT to look at the distortion spectrum. take a look at this guy.
http://www.haslingaudio.com/Grafer/Indexgrafereng.html |
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drwkng
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10-05-20
14:27:35
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| 回覆 (1011): 湯瑪士的第一次 |
Thanks, buddies for the kind words.
My first cow has been compared with the James by listening as well. What I can say at the moment is that at least it sounded normally, no smoke or extraordinary vibration or heat after being fired up for about 30 minutes. I believe that is good enough for a first time stuff.
"""have you measured the FFT spectrum of your beast"""
King, you know I am at most just a handy man but not any engineer. Is that what you mentioned for tracing the full range frequency response? I don't have such equipment but I did have measured the voltage output at various frequencies. There were rolloffs at both the low and high ends but I think the magnitudes are reasonable as the james hehaved similarily as well. I don't have the figures with me now and will post them tonight for your judgement. |
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ThomasC2
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10-05-20
11:17:04
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| 回覆 (1010): 湯瑪士的第一次 |
It's already jaw dropping, when I found out that daiwok fabricates his own resistors last Sat during yumcha. And now you, Thomas, you are absolutely beyond cure, my salute! I am totally speechless.
Don't get overdrowned with measurements, hook it up & hear how it goes. |
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Derek2A3
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10-05-20
10:53:08
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| 回覆 (1009): 湯瑪士的第一次 |
| scope trace can only tell you whether there is something terribly wrong. thomas have you measured the FFT spectrum of your beast? |
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drwkng
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10-05-20
10:23:22
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| 回覆 (1008): 湯瑪士的第一次 |
Looking at the scope, the leading edge is slightly rounded and that may have affected transient attacks.
Proof of the pudding, nevertheless, is in the listening. What is the sound like then?
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limage
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10-05-20
10:13:43
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kris
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10-05-20
06:38:27
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feikeung
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10-05-20
03:54:12
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| 回覆 (1005): My first output transformer |
And here is the reward! Of course I had no intention to build anything "ultimate". The wire I used is from China and the laminations are those scrap called 西電拆機鐵心. With some more practice, trying and better materials (especially the iron), I think I should now be able to say that the making of a reassonably good output transformer should not be as difficult and mysterious as people might have expected.
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ThomasC2
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10-05-20
00:47:14
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ackcheng
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10-05-20
00:35:22
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ThomasC2
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10-05-20
00:31:35
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| 回覆 (1003): My first output transformer |
| After a few days of harding working and frustration, my first "cow" was on the testing bench. It was tested and compared with a James transformer and here is their performance on 10KHz square wave. The upper trace belongs to my "cow" and the lower one belongs to the James. |
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ThomasC2
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10-05-20
00:22:11
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ThomasC2
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10-05-20
00:12:40
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| 回覆 (1001): My first output transformer |
| Without any experience or guidance in the operation of such a machine, it took me some time to familiarize with the settings and eventually I was able to éæé´¨è
³å° make the machine rolls according to what I want it to. |
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ThomasC2
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10-05-20
00:08:42
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| 回覆 (1000): My first output transformer |
First time transformer diyers used to start with power transformer. I was ambitious enough to start with an output. After studying the information and materials I have gathered, I designed this structure for my first output transformer.
It is a 4-primary sections interleaving 5-secondary sections design. Each primary section is further divided into 5 layers. The design was complicated by the desire that all secondary windings can be fully used by both 4 and 8 Ohms output. |
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ThomasC2
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10-05-19
23:55:25
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| 回覆 (999): My first output transformer |
It has been my belief that the output transformer contributes 70% to the sound quality of a tube amp and that the time and effort required for making the output transformer probably share the same percentage of the total amount of time and effort required in building a tube amp. So, if you diy a tube amp with somebody's output transformer, that somebody actually is making 70% of the amp and you are taking care only of the remaining 30%.
It has been my wish that one day I can wind my own output transformer. Today, my wish was realised.
Upon the retirement of one of the very few (probably 2 only) commercial audio transformer winders in HK, I had the chance to acquire this second winding machine with automatic wire laying function (èªåæç·) which is the most essential in the making of audio transformers.
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ThomasC2
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10-05-19
23:37:11
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Vash
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10-05-10
13:25:34
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TaiMonSing
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10-05-10
09:33:56
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Vash
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10-05-10
02:37:19
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TaiMonSing
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10-05-10
02:00:44
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TaiMonSing
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10-05-10
01:59:47
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TaiMonSing
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10-05-03
23:53:25
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daiwok
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10-05-03
23:10:27
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daiwok
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10-05-03
23:08:21
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