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回覆 (303): What I did last night?
 
Bobui, how did you manage to get all those good looking chassis for you DIY projects? Respect!  
 
thekong
11-10-06
17:47:36
回覆 (302): What I did last night?
looks tasty ! 8^)
daiwok
11-10-06
17:42:04
回覆 (301): What I did last night?
Had my soldering iron on until 3:00am last night to finish modify the below SE power amps from direct coupling to capacitor. Not a very complicated process but far more than just adding a cap because all working voltages/resistors and bias has to be re-adjust.  
 
The amp gives out 6 to 7 Watts. ( 400V at 60mA)  
Driver tube is GEC CV1343 (4V faliment)  
Power tube is PX25  
Rectifier is U18 (5V heater)  
Power trans and choke are new old stock Vortexion. An old British brand from 60"s mainly PA and stuido stuffs  
Output tran is as the looks tell you, a 5K Tamura SE  
 
Sound quality? Emmmm, hands down when compare with a well constructed PP amp. However, for horn lovers or speakers require single digit power drive. You may find the sound very smooth and lush.  
 
For those high hands who will be coming over my den soon, feel free to take them home for a run. Of course I supply all the valves!  
 
bobui
11-10-06
17:12:18
回覆 (300): Wine, Food and Valves Night
ackcheng
11-09-30
22:02:17
回覆 (299): Wine, Food and Valves Night
Just managed to get HDMI > SPDIF conversion for my 7.1 channels  
 
http://www.digitalroomcorrection.hk/Site/Home_theatre.html  
 
ackcheng
11-09-30
22:01:50
回覆 (298): Wine, Food and Valves Night
Hi Guys,  
 
I like to invite you to my den for a wine and food evening on one of the following date 29th Oct, 05th Nov or 12th Nov Will send invitation to your PMs later this week.  
 
Wine course start at 4:00pm  
One each of the following: Tattinger NV, Tattinger Rose, Australia Red, French Red, Italian Red. Cheese and Ham  
 
Food - 5 dishes meal in below order  
Steam 2 or 3 X roughly 1 catty Garoupas  
Black pepper Fried Prawns or garlic steam (depending on size)  
Mixed fried mushroom and beans  
US Prime Steak, one each, details to be announced in PM (after I have a chance to discuss with consulting cook diawok)  
Steam chicken rice pot  
 
Desert to be announced (after I have a chance to discuss with consulting chef David Wong)  
 
Various Scotch Single Malt Whisky and blue label blended  
 
Audio  
A Push-Pull of 15 to 30W shootout on the following valves on my custom amp. 6B4G, 300B, PX25, CX350/50, GEC KT88  
 
A Single-ended 1.5 to 8 W shootout on the following valves on another custom amp of mine. Several different PX25s, several different 300B, 45, 50, 10Y, PX4 etc.  
 
All the above will be accompanied by turntables including Wilson Benesch Act2, Alphason (after I have a chance to discuss consulting LP Master Wong Yuk Ming), Linn, Home made with Morch 12" etc.  
 
Three CD players as front end source.  
 
Picture below is a pair of newly arrived PX25 straight bottles that make up to a QUAD set for the shootout.  
 
 
 
 
 
bobui
11-09-30
15:09:23
回覆 (297): New & Old World Tube Testing
Characteristics and Typical Operation  
 
6900  
Class A Amplifier  
Plate Voltage ................................. 120 V  
Grid No. 1 Voltage ............................ -2.0 V  
Amplification Factor .......................... 18.5  
Plate Resistance (approx) ..................... 1600 Ω  
Transconductance .............................. 11.5K µ  
Plate Current ................................. 36 mA  
 
5687  
Class A Amplifier  
Plate Voltage ................................. 120 V  
Grid No. 1 Voltage ............................ -2 V  
Amplification Factor .......................... 20  
Plate Resistance (approx) ..................... 2K Ω  
Transconductance .............................. 10K µ  
Plate Current ................................. 34 mA  
 
Link below for your reference:  
http://www.nj7p.org/Tube4.php?tube=5687  
 
The characteristic difference between 6900 nd 5687 is roughly 10 to 15% on each measure. Thats typically what you will get from non-matched same valve type of differrent brands or even same valve type same brand. Right?  
bobui
11-09-23
13:18:18
回覆 (296): New & Old World Tube Testing
6900 is not a 5687. As far as i could remember, 6900 is weaker, in terms of Ia, than 5687. A tube tester tests a tube by fixed bias. If at a fixed, say, -2V Vg, a standard 5687 should give something like 2 mA Ia, at the same -2V Vg, a 6900 might give 1mA or even less Ia. However, if the Vg is lowered a bit to, say, -1.6V, the Ia of the 6900 can be raised significantly to probably over 2A.  
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it is not just lower. it indicates the tube is almost dead. looking at the display, it expects to measure 12ma whereas it only measures 0.2ma. that can't be right!  
 
 
 
i think first of all you should define who would be the users of your tube tester, if there would be any. It those would be the ordinary hi-fi yaus or tube users, you should forget the different working conditions.  
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well, i don't know. even the old tube testers can be used to test different working conditions. given the group of this Amplitrix, what i'm going to make will be very specific. i'm going to build one for testing tube with PC. the tube tester only controls the voltage etc, the PC will do FFT on plate output. so i need to build an interface to the sound card etc
drwkng
11-09-23
10:51:58
回覆 (296): New & Old World Tube Testing
'''.......and i was susprised to find that you can't test the same tube with different settings. that's a bit limited. for the same tube you might have different working conditions for different amps.....""  
 
i think first of all you should define who would be the users of your tube tester, if there would be any. It those would be the ordinary hi-fi yaus or tube users, you should forget the different working conditions.
ThomasC2
11-09-22
22:11:20
回覆 (295): New & Old World Tube Testing
""""it fails to measure a pair of 6900 using the 5687 spec""""  
 
 
I guess.....  
 
6900 is not a 5687. As far as i could remember, 6900 is weaker, in terms of Ia, than 5687. A tube tester tests a tube by fixed bias. If at a fixed, say, -2V Vg, a standard 5687 should give something like 2 mA Ia, at the same -2V Vg, a 6900 might give 1mA or even less Ia. However, if the Vg is lowered a bit to, say, -1.6V, the Ia of the 6900 can be raised significantly to probably over 2A.  
 
In most real circuits, eg, your preamp, I believe the 5687 works in auto/cathode bias and sometimes even under direct coupling with the former stage. In such a auto/cathode bias circuit, a 6900 might again not work exactly like a 5687 in the place of a 5687. However, the coordinate relationship between the Vg and Ia might be able to "tune" the 6900 to run under conditions which can still be regarded as workable (especially when being judged merely by human ears!!!) .  
 
For reference, based on the settings suggested for my AVO, I found Ia of the tens of 12AX7 I own, new and old, ranged from 0 mA to 1.5mA (while the standard should be 2mA). Again, if i alter the Vg just a very little bit, the Ia would change a lot. When plugged onto any 12AX7 circuit, they all apparently work very fine.  
 
Hope the above would not be found too nonsensical.
ThomasC2
11-09-22
21:56:58
回覆 (294): New & Old World Tube Testing
i know there is pc program. and this is my point. you need to use the program to change any setting. and i was susprised to find that you can't test the same tube with different settings. that's a bit limited. for the same tube you might have different working conditions for different amps. so it looks like i still need to make one for myself.
drwkng
11-09-21
20:01:37
回覆 (293): New & Old World Tube Testing
It looks like the Tube Data File is different from the firmware. There is a file like the Tube dictionary file. It governs what tube the tester can "see" and test. So if there is a tube you want to test but not on the dictionary, you need to add the spec of that tube to the dictionary file. There is a Program/Software to help doing that.  
 
http://www.amplitrex.com/download/Tubedata_Editor_Manual_12-2006.pdf
icefox
11-09-21
16:31:27
回覆 (292): New & Old World Tube Testing
咁即係話有死穴?  
--------------------------  
 
I prefer a test equipment to be bullet proof and well construct. If well meaning simple, then be it!  
 
bobui
11-09-21
16:20:14
回覆 (291): New & Old World Tube Testing
Dr. King, interesting report on the 6900. according to the URL, the tube support list definitely is not as extensive as the old world tester like AVO.  
 
I am indeed quite curious when there is a tube not being supported in the current firmware, what could be done? Need to wait for the manufacturer firmware upgrade or one could indeed use the pc to program the support.
http://www.amplitrex.com/tubelist.html
icefox
11-09-21
16:15:12
回覆 (291): New & Old World Tube Testing
it fails to measure a pair of 6900 using the 5687 spec  
_____________________________________________________  
 
咁即係話有死穴?
Derek2A3
11-09-21
16:10:17
回覆 (290): New & Old World Tube Testing
i had a play with this beast last week. it looks o.k. function is limited. may be i don't know enough. many setting have to done thru pc instead of a self contained unit. interesting thing is that it fails to measure a pair of 6900 using the 5687 spec.  
drwkng
11-09-21
15:44:10
回覆 (289): New & Old World Tube Testing
http://www.nostubestore.com/p/test-bench.html
icefox
11-09-21
15:09:35
回覆 (288): gang bang --- AMPLITREX AT1000
naked photo.
icefox
11-09-21
15:05:01
回覆 (288): For the tube head!
icefox
11-09-20
11:37:15
回覆 (287): gang bang --- AMPLITREX AT1000
 
 
How about the idea of 1PekingRoad.com (willing) members coughing up a few hundred bucks per head and gang banking the AT1000?  
 
1) On9Keung  
2) Derek2A3  
3) icefox  
4) limage  
5)  
6)  
7)  
8)  
9)  
10)  
11)  
12)  
 
 
limage
11-09-17
10:46:31
回覆 (286): gang bang --- AMPLITREX AT1000
How about the idea of 1PekingRoad.com (willing) members coughing up a few hundred bucks per head and gang banking the AT1000?  
 
1) On9Keung  
2) Derek2A3  
3) icefox  
4)  
5)  
6)  
7)  
8)  
9)  
10)  
11)  
12)  
________  
 
I am absolutely glad that someone high up in the ladder at the 阿公 level makes this proposal. Make no mistake, I absolutely want to show my support, both monetary and spiritual support to our Resident Dr. However, during out last gathering, I realize that now Dr. king merely has a corridor worth of space left in his den. It will be quite devastating if he starts another new project. I don't think he is going to use the 27D casing for the DIY tube testing kit, it makes no cost sense. This means he may end up ordering another batch of huge inventory to keep a couple of handful 粉腸 happy but willing to pay peanuts (including me).  
 
However, looking at the Amplitrix, it looks like a nice full blown solution. I have personally seen and touched a unit. It's quite solidly build, when you hold it, you feel like holding a case of secret weapon prepared for 007. I have seen the operation of it, and it's a breeze to use. I've not even explored its northbound computer interfacing capability yet. I am indeed trying to set something up.  
 
On the math side, I would not under estimate the valve inventory of our fellow inmates, however, at most, given you 2 weeks of access to the Amplitrix, I think it would allow you to test most if not all your valves for one round. Thus, if we can secure 15 interested folks, 2x15=30 weeks of usage. We still have 22 weeks left as idle for booking amongst the fellow inmates within the circle. We can definitely explore other biz opps when there is really free time, say in the Year 2 operation of the investment. This makes stronger economic sense to me.
icefox
11-09-16
22:55:08
回覆 (285): gang bang --- AMPLITREX AT1000
 
The AVO has served me admirably for the last 20 odd years despite its primitive design. As long as its core value remains the same --- that it works without hassle, I would be happy to keep this bird in hand.  
 
Well I don’t mind to be proved wrong soonest I am convinced. If a computerized update has proved to work wonders, I won’t be the last one to keep up.  
 
limage
11-09-16
16:11:39
回覆 (284): gang bang --- AMPLITREX AT1000
> with the advent of microcontroller and analogue to digital converter, these capabilities seem pretty primitive.  
 
Old Fart is proved wrong again.  
It's time to update his mindset's firmware.  
 
feikeung
11-09-16
14:50:59
回覆 (283): gang bang --- AMPLITREX AT1000
Alternatively, I’ll dish out US$2675 + US$199 (6C33C adaptor), pay cash up front for the beast, and charge you a HK$100-200 per session until the capital is paid off. From there on, it becomes permanent property of 1PekingRoad.com and will be in 寨主"s custody.  
 
http://www.amplitrex.com
feikeung
11-09-16
14:48:23
回覆 (282): Tube tester / 最奇摩機
with the advent of microcontroller and analogue to digital converter, these capabilities seem pretty primitive.  
_______________________________________________________________  
 
Couldn't agree more
Derek2A3
11-09-16
14:39:23
回覆 (283): gang bang --- AMPLITREX AT1000
How about the idea of 1PekingRoad.com (willing) members coughing up a few hundred bucks per head and gang banking the AT1000?  
 
1) On9Keung  
2) Derek2A3  
3)  
4)  
5)  
6)  
7)  
8)  
9)  
10)  
11)  
12)  
Derek2A3
11-09-16
14:37:30
回覆 (282): gang bang --- AMPLITREX AT1000
How about the idea of 1PekingRoad.com (willing) members coughing up a few hundred bucks per head and gang banking the AT1000?  
 
1) On9Keung  
2)  
3)  
4)  
5)  
6)  
7)  
8)  
9)  
10)  
11)  
12)  
 
feikeung
11-09-16
14:33:49
回覆 (281): Tube tester / 最奇摩機
The AVO 163 is a universal tester which was made to thoroughly check tens of thousands of valves available up to the sixties. The wiring involved is brain scrambling, to say the least.  
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that's true but for modern man, the thousands probably reduce to less than 50.  
 
It is in fact more than a tester as its name, valve characteristic meter, wants to indicate. You could easily plot as much graphs as you want with this machine if you happen to be technically inclined.  
-----------  
with the advent of microcontroller and analogue to digital converter, these capabilities seem pretty primitive.
drwkng
11-09-16
13:58:49
回覆 (280): Tube tester / 最奇摩機
 
 
if that AVO can ask for 8k, i'm sure we can do it cheaper  
_______________________________________________  
 
The AVO 163 is a universal tester which was made to thoroughly check tens of thousands of valves available up to the sixties. The wiring involved is brain scrambling, to say the least.  
 
It is in fact more than a tester as its name, valve characteristic meter, wants to indicate. You could easily plot as much graphs as you want with this machine if you happen to be technically inclined.  
 
limage
11-09-16
12:32:05
回覆 (279): Tube tester / 最奇摩機
Count me in if your newly designed tube tester can handle 6C33 tube. Suggest to include low voltage burn-in feature to extend tube life.  
 
Hope yours is a low cost design.  
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it is a diy tube tester. you have to build it yourself.  
low cost design? if that AVO can ask for 8k, i'm sure we can do it cheaper^-^
drwkng
11-09-15
17:24:34
回覆 (278): Tube tester / 最奇摩機
Sound like you will pack a lot of fuctions and features in one small tester. How about offer a basic model and the options to upgrade to a remote version, headphone for microphonics etc. Kind of like what they do in the motor industry.......323i, 325i, 330i, M3 .............most high hands would just love it!  
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you probably haven't seen my preamp. i don't like knobs. it would easier for me to do it with remote than do it with all those knobs^-^
drwkng
11-09-15
17:23:16
回覆 (279): Tube tester
 
A rare AVO 163 is now on ebay !  
 
Unique features of this tester is that both anode current and trans-conductance are shown simultaneously by two big meters while dual triodes can be checked handily for consistency between channels by simply flicking a switch.  
 
http://www.ebay.co.uk/itm/AVO-VCM163-Valve-Tester-full-working-order-tube-tester-characteristic-meter-/230669753960?pt=UK_Consumer_VintageAudio_RL&hash=item35b4fd1e68
limage
11-09-15
16:21:21
回覆 (278): Tube tester / 最奇摩機
Dear King,  
 
Count me in if your newly designed tube tester can handle 6C33 tube. Suggest to include low voltage burn-in feature to extend tube life.  
 
Hope yours is a low cost design.
dkyyu
11-09-15
14:38:31
回覆 (277): Tube tester / 最奇摩機
Sound like you will pack a lot of fuctions and features in one small tester. How about offer a basic model and the options to upgrade to a remote version, headphone for microphonics etc. Kind of like what they do in the motor industry.......323i, 325i, 330i, M3 .............most high hands would just love it!  
 
Oh, allow me to suggest you to name the basic model as "The Servant", next grade up would be "The Prince" then "the Queen", "The King", "The King Special". "The King Limited", "The King Ultimate"..........etc.  
 
bobui
11-09-15
14:12:33
回覆 (276): Tube tester / 最奇摩機
i had another look at the Amplitrix tube tester. it hardwires all the filament supply to those sockets. anything tube that does not fall into the pin configuration, one has to use an adaptor. if Amplitrix can do that, then i suppose it is good enough for our make-do diy tube tester.  
so i will settle on three sockets to start with, namely octal, 9 pin, 4 pin and 5 pin. it will come in two chassis to make life simple, namely the controller and the tester.  
i will use a remote control to operate the tube tester. any philips rc5 remote will do. it will have a 4 lines LCD display. one can select the tube type, set the plate voltage, current and grid swing to be tested. the tube tester probably will perform a sanity check on the plate voltage, current and grid swing as per tube type selected. the tester will then test the gm and possible any short. i might add a headphone output/built in speaker later on to listen to microphonics.
drwkng
11-09-15
13:45:31
回覆 (275): Tube tester / 最奇摩機
又聽住先啦!  
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do you want one then?
drwkng
11-09-15
13:29:58
回覆 (274): Tube tester / 最奇摩機
"""You will be amazed what a Signal Gen and a good voltage meter can tell you! """  
 
just a reminder for those who are preparing to test their tubes with a sig gen and v meter as suggested, first of all, find out the frequency range of the ac your v meter can measure (accurately)  
 
""""".隔離台師兄post 出來,上手摩幾奇,好好笑 """"  
 
Just asked last night a c-hing why people these days are not doing something more meaningful. His answer was they simply don't how to do anything more meaningful. I like this answer.  
 
 
"""For the majority of users, there is hardly the need for a universal tube tester. What they require most is kind of simulator approximating the amps in use"""  
 
"""do you mean testing the tubes at the operating point of the amp?""  
 
Bearing in mind the number of "amps" that can be in use, the variety of the tubes thereon and the wide range of working conditions that can be involved, eventually we probably will be seeing the most universal tube tester in history.  
 
"""i'm thinking of a simple to use tube tester for some common audiophile tubes.""""  
 
又聽住先啦!
ThomasC2
11-09-15
13:09:00
回覆 (273): 最奇摩機
網址
http://www.review33.com/avforum/forum_message.php?topic=11110914165147
jcml
11-09-15
12:07:34
回覆 (272): 最奇摩機
隔離台師兄post 出來,上手摩幾奇,好好笑:  
 
http://www.review33.com/avforum/forum_message.php?topic=11110914165147
jcml
11-09-15
12:06:39
回覆 (271): tube tester
仪器不是万能的,没有仪器却是万万不能的!  
 
__引之胆艺轩。
cpyip
11-09-15
06:52:30