DIY 自作派同好同學會 |
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回覆 (148): Gold Ginger Photographer!
 
>Then the estimate Power Consumption, woooooow, would probably rise up to 2,000Watts plus. And thats roughly 10A at 220ac mains continuous, not surge current. <  
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Ah yes, 3 phase power supply is definitely in my plan!  
 
Now, please give me a rough estimation on the power consumption here. For my ultimate dream stacked ESL57/Apogee Fullrange Bass/Maggie ribbon tweeter system, I would need to employ up to 6 ARC Classic 60 (8 6550s each with triode connection) and a pair of CJP8A, involving a total of 64 6550s plus 36 small signal tubes! ;-)  
 
 
 
thekong
11-07-11
13:24:05
回覆 (147): Gold Ginger Photographer!
I don't know ..... I have too much power with my 2W amps at home !
daiwok
11-07-11
13:20:08
回覆 (146): Gold Ginger Photographer!
Ah, icefox is also correct! If you decided to leave the current SFs system on so you can make a direct comparison with the 2 pairs CJs set up just by switching speaker cables. You do end up having 56 KT88s at your den.  
 
Then the estimate Power Consumption, woooooow, would probably rise up to 2,000Watts plus. And thats roughly 10A at 220ac mains continuous, not surge current.  
 
When you have a set of power amps consuming more power than your air con. It's not sometimes we get the chance to see everyday. You are talking about a lot of heat. A lot of power!
bobui
11-07-11
12:38:46
回覆 (145): Gold Ginger Photographer!
Ah, I took icefox number of "56".  
 
Ok, thats 960Watts just for the KT88s. Include all the voltage gain valves 5751, 6SC7s, max signal ma increase on the KT88s (Class AB1) etc. You prabably looking at roughly total 1,200 to 1,300Watts instead for the 2 pairs of CJs.  
bobui
11-07-11
12:18:39
回覆 (145): Gold Ginger Photographer!
 
>Here is the maths. 56 X 500v X 60ma = 1,680Watts (Power Consumption). <  
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If counting just the KT88/6550, there are "only" 32 of them in 2 pairs of CJP8As. So, would that make the power consumption around 960W instead?  
 
thekong
11-07-11
12:06:13
回覆 (144): Gold Ginger Photographer!
56 valves massive amplification systems.  
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Here is the maths. 56 X 500v X 60ma = 1,680Watts (Power Consumption). If include all the small voltage gain valves such as 5751s and 6SC7s etc. You are looking at a total of roughly 1,800W just for the two pairs CJs line up.  
 
500v is roughly the working voltage of the KT88 in the CJ at 60ma which equal to 30W. The max pa.in Watt for the KT88 is 35W.  
 
To put it in reality:  
A 50" to 60" LCD consume average 300W  
A clock radio consume average 4W  
A desk top with 17"LCD consume average 200W  
 
The only thing come close is a split air 1.5tons Samsung air condition consume average 1,500W  
 
"Size Does Matter"
bobui
11-07-11
11:56:52
回覆 (143): Gold Ginger Photographer!
 
>Look forward to the voicing of this 56 valves massive amplification systems. <  
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Thanks Icefox, you will be the first to know when the system is up and running! :-)  
 
thekong
11-07-11
11:25:54
回覆 (142): Gold Ginger Photographer!
"the good surprise from the photographer's gold fingers on the "Pass" 四粒."  
 
Those CJ P8a........... are simply gorgeous, congratulation kong!!! Look forward to the voicing of this 56 valves massive amplification systems.
icefox
11-07-11
11:22:57
回覆 (141): GEC KT88s vs. Goldlion (replica)
 
I must give great thanks to Bobui for his visit and the generous offer of putting his NOS GEC KT88s against the re-issue Gold Lions. Our golden finger photographer, Alan Soo, also showed his skill on my Pass 四粒! With his experience on the Pass十二粒, it was no wonder the四粒 was just child play for him! Following his suggestion of changing the Xover slope from 18db to 12db, the problem of a slightly lack of body at the mid bass region has been solved, and with better coherence between the mid/high and the bass.  
 
Regarding the difference between GEC KT88s and the re-issue Gold Lions, as Bobui has reported, the GEC has slightly more air and better high frequency definition, but the basic tone is very similar between the two. The GEC will probably improve further with burn-in, and I will have to do more tweaking to see if the reissue GL can be made to sound more like the GEC!  
 
 
thekong
11-07-11
11:15:54
回覆 (140): GEC KT88s vs. Goldlion (replica)
Thanks to Evil Kong for making it happened, finally! Also to icefox mangement skill and the good surprise from the photographer's gold fingers on the "Pass" 四粒.  
 
Race Report:  
 
Emmmmmm, Ahhhhhhhh, Emmmmmm, Sure, difference can be heard, more air and greater detail in the treble. Overall, not as obvious as one may wish for. Not sure if it was because of the narrower bandwidth the amp with the GEC's only need to handle (2 ways electronic crossover with seperate amps for high and low, GEC on the high) or could I just say the Goldlion is very well made!  
 
Ok, ok, not fair to make full judgement on a single comparsion especially Evil Kong set up is so good with almost no room for improvement and full of characters already!  
 
Dr Kong, let us know if the sound evolve after burn in please. You see, the more "burnt" the GEC valves become, the less you have to pay for them. No, just kidding! They are for your enjoyment, not for pocession!
bobui
11-07-11
10:13:25
回覆 (139): 811-10 Circuit
always compromises here & there not to mention personal preference.  
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I am so excited about this project. Sure you know how it feels when there is a chance to make something not so common. A 100W triode valve amp. If the amp can deliver 80% of the power at around 3 ohms on the 8 ohms terminal, its going to beat a pentode connected 200W amp.  
 
Keep you posted with pictures on component layout before I fix them with a drill.
bobui
11-07-06
17:49:18
回覆 (138): 811-10 Circuit
bobui, there is no perfect circuitry, but there are always compromises here & there not to mention personal preference. If your gut feeling tells you that this is the one, just proceed & see how it goes. Debugging, modifications & fine tuning can always be done afterwards.
Derek2A3
11-07-05
23:02:32
回覆 (137): 811-10 Circuit
Derek2A3, thanks for sharing. Could leave more headroom for sure but since it is a cathode follower, there will be no gain and positive drive is a lesser concern. The AB2 is a very very good reminder. Thanks! In fact, I have been scratching my head last week on how best to avoid grid current for a valve with such high mu! The idea was to run higher HT, I wish I have near max 760DC but the transformer I just purchased only has 520ac, would be lucky If I can get 700DC. Let see how well these trans were made in terms or regulation.  
 
I have a pair of 650ac trans but the current is far too below what I need. Too bad!  
 
Almost all factory figures measured at one single frequency at a fixed load impedance. My idea is to build a valve amp that can continue to deliver at falling impedance. That matters to me more. Share your thoughts please. It's meant to be fun!  
bobui
11-07-05
20:02:56
回覆 (136): 811-10 Circuit
bobui, I don't have any experience with 6J5, just remember that it's like a single triode 6SN7 (u=20) within an envelope. If that's true the phase splitter which right now being biased at -5 volts might be marginal. Say you have a signal of 0.3 V, after the input stage, the resultant amplitude would be around 5V, your phase splitter might run out of bias.  
 
If you intend to run class AB2 someday, the 6BX7 would need more current to fulfill the task. Just brainstorming!
Derek2A3
11-07-05
17:53:22
回覆 (135): 811-10 Circuit
A pair of below transformer I recently purchased for the 811-10 project over the weekend. Max at 520 and 500ma which give me roughly 700v DC and 375ma.  
 
Also got a pair of same make heater transformers which allow me to supply the 4 811-10s with seperate DC LT. What a nice way to keep the 50hz harm down.  
 
Alll I need now is to start sourcing the components and start working!  
 
Drilling lor!
bobui
11-07-05
12:38:00
回覆 (134): 811-10 Circuit
Happy because I finally got a pair of power transformers for my 811-10 project. Not happy because the KT88 shot out was not well organised.  
 
Kong, please check your sms  
 
Below is my revised circuit. I ditched the 6B4g as splitter/driver and replace with 6BX7GT.  
 
1. First 6J5 direct coupling to the phase splitter to keep phase shift small. Equal load in the phase splitter aslo behave like a cathode follower. Grid of phase splitter at around 100V.  
 
2. 6BX7 running at around 10ma per side. No more heat problem with the common cathode resistor as it no longer carry high voltage. A variable load resistor to compensate any inbalance in the two sections AC level.  
 
3. The fixed bias of the four 811-10 use a similar network as the Marantz10. Each 811-10 set to run at 70ma, 700V anode and roughly -40 negative bias. Each pair produce roughly 40 to 45 watts. PPP gives a total of 90 to 100 watts.  
 
Output is a sowter 7K 100 watts. Can stand 250ma per side in case it run into class AB2. Overall feedback is optional between 10 to 20 db.  
 
Do commnet and tell me if it look strange to you.  
bobui
11-07-05
12:29:12
回覆 (138): Connectors
I want to create a lead such that I can re-use this P/S for my Onix BWD-1 tuner to replace this very chicken cow.
icefox
11-06-25
03:00:42
回覆 (137): Connectors
but what's it for?  
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For this.
icefox
11-06-25
02:49:53
回覆 (136): Connectors
What is the trade name for this connector? DIN?  
 
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it's a 6-pin DIN. i have one exactly the same on my hand now......  
 
but what's it for?  
 
mdlover
11-06-24
20:17:06
回覆 (135): Connectors
Vash and fellow DIY experts,  
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Doesn't look like a Din to me. Can go and check it out when i next go to Bush (they have a print version catergory) to pick up my KT88s.  
 
Wish u can get a quicker answer from friendshere.
bobui
11-06-24
17:19:24
回覆 (135): Connectors
Yes, it is a kind of DIN. You can take this DIN to Wah Fai in Apliu street, they do have wide range of choice for you.  
 
Hope this help.
Vash
11-06-24
17:16:46
回覆 (134): Connectors
Vash and fellow DIY experts,  
 
May I know if I can get this connector from RS or Farnell or Duck Street?  
 
What is the trade name for this connector? DIN?  
 
Photobucket

 
Photobucket

 
Photobucket  


 
icefox
11-06-24
16:43:36
回覆 (134): -
Great tread, guys; plz keep it up.
Willleung
11-06-22
02:02:55
回覆 (133): 811-10 Circuit
My second pair of Lowther Acousta that came in together with the many pairs of ESL.  
 
The cabinets were in very good condition. I replaced the stain grill cloth to new black klipsch classic series. I sand off the lacquer and apply thin "OSMO" half satin finish. OSMO is Eco friendly. All you need is to apply very thin coat with a cloth, its very easy to use, no paint brush needed. Once dry, the half satin finish is very natural.  
 
http://www.osmona.com/
bobui
11-06-21
12:51:30
回覆 (132): 811-10 Circuit
ThomasC2, much appreciated for your advise. I didn't pay much attention to the heat problem. I will revisit the use of 6B4G today as it generate cooling problem from the big cathode and anode resistors. Perhaps I shall look at 6BX7 as phase splitter.
bobui
11-06-18
09:24:46
回覆 (133): spot welding
Seems to me that copper welding is usually done by 風煤。  
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You can be right, at least that's what those 冷氣佬 has been working on for decades. Thanks for the info. Welding has been widely adopted for stainless steel, but never copper, least to the best of my knowledge in consumer items, may be steel can't even be soldered. But with this limited mind, I can be wrong again. Still recalled decades back, 雷明 described in his article that the beauty of those Hitachi interconnects were that they were welded to the RCA plug instead of soldering. That's one of the reason I've been fantasizing about welding. Since I've started the journey, let me walk on & see how it goes. Mistakes can still make history, as long as you documented it so others don't repeat your foot steps. You know what I mean.  
 
 
RCA plugs and sockets are usually made of brass and electric wire is always made of copper. I wonder whether these two different substances would happily bond together even if you have the heat high enough to melt they both.  
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Thomas, you might be spot on again, just love to see your rationale. In fact I was thinking along the same track for an explanation. Another thing I was thinking is that copper may be too soft/ductile for the task. Hopefully more can be posted for yours & others comments in the near future. See what I can come up with before saying "I am done".
Derek2A3
11-06-18
00:24:23
回覆 (132): spot welding
"""" These machines were designed to weld stainless steel & not copper."""  
 
 
Don't know anything about spot welding. Seems to me that copper welding is usually done by 風煤。  
 
"""One example, the RCA male centre pin, too short a duration, wire & plug separates once you twist the cable. ........."""  
 
 
Just my guessing. RCA plugs and sockets are usually made of brass and electric wire is always made of copper. I wonder whether these two different substances would happily bond together even if you have the heat high enough to melt they both. As I said, just my guessing.
ThomasC2
11-06-17
23:04:35
回覆 (131): 811-10 Circuit
My 2 cents:  
 
""""Should be 200V at grid and roughly 245V at Cathode. The 50ma is per 6B4G. """  
 
Certainly you would need to re-allocate that 700V HT along the anode to cathode path of the 6B4G if you really want a Va of 300V.  
 
Why 6B4G as driver especially when you would be using fixed resistor as anode load and have direct coupling with the 6SL7 ? Have you considered the amount of power that would need to be dissipated/wasted at the anode and cathode resistors? If the 6B4G would really be running at 50mA each, that would be a total of over 40W of heat per each channel just on those resistors.  
 
Also, as the signal voltage output by the 6B4G would be further amplified, I envisage a mission not too easy in dealing with the filament noise.  
 
I suggest a small value resistor at the anode of each of the 811s.
ThomasC2
11-06-17
22:52:39
回覆 (130): 811-10 Circuit
I'll say 30 ma per tube  
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I think I see where you heading. I have the habbit to run triode hot and 80 to 90% max but for voltage swing more the current drive. Perhaps a low ma should be considered. I am currently running at 55ma. per 6B4G on my push pull amp. And I do hear difference even with a few ma less.  
 
As for the 6SL7, I am using both sections for one channel, so internal resistance become half. Didnt make myself clear in the hand drawing!
bobui
11-06-17
15:46:56
回覆 (131): 811-10 Circuit
start to comment  
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Too traditional, may be! Anything obvious or doesnt make sense to you? Anything is better than nothing. Try me!  
bobui
11-06-17
15:37:43
回覆 (130): 811-10 Circuit
i don't know where to start to comment. it is just not my cup of tea^-^
drwkng
11-06-17
15:32:25
回覆 (129): 811-10 Circuit
The 50ma is per 6B4G.  
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I have reservation on that too if you don't mind, cos the 811 aren't drawing any grid current. I'll say 30 ma per tube should be fine for the task. But again double check the curves of 6B4G to get an operating point that would give you similar gain on either of the curve.  
 
Another note is about the anode resistor for the 6SL7 which has an anode resistance of about 62k, if memory serves, partnering it with a 100k resistor won't give you a very linear output. Try 220k & work out the current requirement, shouldn't be too difficult since you have a lot of HT. Just my 2 cents
Derek2A3
11-06-17
15:20:09
回覆 (128): 811-10 Circuit
206-200V, you only have a -ve grid bias of 6V  
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Thanks for that, yes, a mistake that can cause 2 lovely 6B4G turn red and expolit right at switch on. Should be 200V at grid and roughly 245V at Cathode. The 50ma is per 6B4G.  
 
bobui
11-06-17
14:48:48
回覆 (127): 811-10 Circuit
bobui, running the 6B4Gs at 50ma, bet you are talking a pair not one, isn't it? I am worried about the grid cathode potential of the 6B4Gs, 206-200V, you only have a -ve grid bias of 6V, normally speaking, this tube should be biased around -ve 45 V or even higher. Pls double check the operating point. May be there's something I missed.
Derek2A3
11-06-17
14:41:12
回覆 (126): 811-10 Circuit
Guys, do leave your comments or questions. Suggestions and recommendations are very very welcome.  
 
The orange highlighted working voltage is ideal and Cathode resistors in ? pending for correct values.  
 
Each 811-10 run at 75ma, 750v or 56.25W  
 
6B4G run at 50ma, 300v. or 15W  
 
Most of the voltage gain come from a 6SL7 and firect coupling to the grid of 6B4G. The variable resistor in the 6B4G Anode circuit allow slight adjustmetn for AC inbalance due to the nature of the phase splitter and variation in tubes. Optional negative feedback at roughly 10 db.  
 
 
Most important to the stability of the circuit is the working voltage for the 6B4g (200v grid and 206v Cathode). The 811-10 is targeted to run mostly in Class A with a negative grid bias roughly at 50v. Transformer is 7K a to a which translate to 7k load for each 811.  
 
bobui
11-06-17
14:13:36
回覆 (125): 811-10 Circuit
bobui
11-06-17
13:58:28
回覆 (124): spot welder
were designed to weld stainless steel & not copper.  
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Stainless not much use for hi fi chassis? planning something big?  
 
hectic at work today. show you circuit tomorrow
bobui
11-06-16
18:22:26
回覆 (123): spot welder
Spot welding turn out to be not as simple as what we saw on the net. These machines were designed to weld stainless steel & not copper. I've tried both, with steel the bond is pretty strong, but with copper, bonding strength is weak ie. detaches fairly easily if the two parts move relative to each other. Solders may still be needed after welding to secure the contact.  
 
To make things worse, with different thickness/mass of the material to be welded, you need different settings & duration to have it done nicely. One example, the RCA male centre pin, too short a duration, wire & plug separates once you twist the cable. Too long, the centre pin just melts & structurally collapses. The poor male plug has no where to go but ended up sitting in a garbage bin. Nonetheless, after all the disappointments & fury, sonic results are promising. Stay tuned!
Derek2A3
11-06-16
16:24:57
回覆 (122): DIY 自作派同好同學會
adequately filtered or you use center tap of the LT trans  
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Thanks for advice and sharing. I would probably post the circuit here tomorrow instead of send to your pm. Make myself look foolish is way better than blowing up the amp at switch on. That cant be too smart?  
 
Yes, the faliment is always an issue once you get into the detials. Thats kind of the reason why I prefer dc faliment and seperate supply for each output and 6B4G. No No No and you are correct. I dont want grid current and i want a steady supply of current to the ouptut not affect by the dip in speakers impedence. When the speaker impedence dive, the secondary on the ouptut transformer will reflect back to the primar in the same ratio. That would make the output valve to attract more electrons to the Anode and draw higher current. The so call "Current Clipping" commonly happen in valve amp. The dream of driving the Maggies and Apogee will never be possible. See where I am heading. Simple Class A PPP amps! 100W Triode la.  
 
bobui
11-06-15
16:40:13
回覆 (122): spot welder
Going to collect a spot welder tomorrow on load from an old class mate. Many of us fantasized on the merits of welding, now it's time to give it a shoot out. First test that come across this simple mind is to construct 2 pairs of interconnects, one with soldering & the other with welding, then perform a comparison.  
 
Now gents, I need your inputs on what other interface can the spot welder be of use for a simple AB test. Thanks in advance.
Derek2A3
11-06-15
16:39:08