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回覆 (210): Goto Full Monty
 
>First: Which one is the Goto horn? I can see Exclusive, thats Pioneer.  
Last. niceeeeee, you can get this one. Go on! Can you get one? <  
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What a knowledgeable and understanding wife that you have, you are such a lucky man! :-)  
 
 
thekong
11-08-15
17:04:31
回覆 (209): Goto Full Monty
time for some bigger horns !  
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No offence, funny sharing of a family conversation on HORN  
 
Late last night, I told Mrs bo bui what a special night I had at the photographer's den hearing and seeing the Goto horn. Surely, she has absolutely zero idea why I made such a big fuse about it. She just said: "You already have one, no more". I then spent the next 30 minutes trying to explain to her the Lowther we have is such a baby and what we need is a grown up. She looked me in the eyes and said nothing. So I kind of just follow through the flow and chase for an upgrade approval. To my surprise, she kind of said ooooookkeee la if the horn looks is good and fit in my living room. "My living room"! So I show her three pictures to comment.  
 
First, the photographer Goto horn set up.  
Second, the picture diawork listed a few steps below with Lowther as bass horn.  
Last, Living Voice right here.  
 
And her answer is.  
First: Which one is the Goto horn? I can see Exclusive, thats Pioneer.  
Second: .......................No way, water pipe!  
Last. niceeeeee, you can get this one. Go on! Can you get one?  
 
bobui
11-08-15
14:54:31
回覆 (208): Goto Full Monty
Full Monty!!!  
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Goto, Goto, horn, horn, horn, Goto, horn, bass horn, Goto bass horn!  
 
A family union photo! What more can you ask for in life!
bobui
11-08-14
15:03:31
回覆 (207): Goto Full Monty
wow, I kind of feel that the Exclusive 15"s were trying hard to catch up with the speed of the Goto.  
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Goto, Goto, Goto........ top to bottom, full monty!!!
icefox
11-08-14
13:09:11
回覆 (206): UTC小牛作LPF
time for some bigger horns !  
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The speed and power of the Goto, wow, I kind of feel that the Exclusive 15"s were trying hard to catch up with the speed of the Goto.  
 
The effortless of the whole system in expressing lower to high level sound was second to none. Super quick, Super Scale! Super loud! Super dynamic!  
 
But to my ears when I requested the DJ to play a simple piano piece, then, I thought, Ok Lowther, I can still live with you. Just need to make sure I stuck it close to my ear and not gamble it with all my savings!
bobui
11-08-14
11:54:19
回覆 (205): UTC小牛作LPF
Goto makes my Lowther like little hand held radio  
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I also feel the same :-(  
 
SIZE MATTERS !  
 
time for some bigger horns ! Also made for GOTO !  
 
Evil Kong - don't you love the tweeter horn and you can get a 1m Dia horn as well !  
 
bobui - the bass horn is a lowther !!! there is a lowther in that square box.  
 
daiwok
11-08-14
11:35:21
回覆 (204): UTC小牛作LPF
最近心思思用utc小牛  
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Weekend sharing:  
 
Friday night - went to visit an old friend, the photographer's big den and his Goto. Good god! Size is the matter but price is not! Goto makes my Lowther like little hand held radio that you see the horse gambler stuck to their ears in victoria park!  
Just forget Lowther and perhaps most other horns! Get the Goto. The imaging is super!  
 
Saturday morning - see my other bike. A ciocc wth campagnolo Record C, Delta brakes, record 9 speed etc. All classics stuffs. Very smooth ride. Roughly 19 pounds.  
 
Saturday evening - got itchy in the butt, hook up my UTC HA-100 mc cow. Good god! Still one my my most loved MC cow. Some UTCs can really surprise you lor! Just watch out the spec, because for instance the CG series is only made limit to 15Khz.
bobui
11-08-14
10:18:02
回覆 (203): UTC小牛作LPF
UTC小牛
cpyip
11-08-14
06:33:56
回覆 (202): UTC小牛作LPF
最近心思思用utc小牛,代替原來的臺制牛:结果听感上不是一般的好,好太多了。這里似乎牛的质素還是不能马虎。  
 
我是pin 6、7、9落地,4.5k作IN,p1n 1、2作OUT的。  
大概是:分析力很好,高中低均衡,質感特出。可說是近日來一大收获
cpyip
11-08-14
06:32:35
回覆 (201): Ordering parts from Mouser
After many testing and positioning, I can finally get a good impulse response curve from my speakers. But....... there is no garantee that it sounds good!
ackcheng
11-08-12
23:09:51
回覆 (200): Ordering parts from Mouser
How to choose ? Are those with bigger numbers better or power amps dependent?  
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The seller should indicate the readings between each valve in a quad set. Not much use between quad sets. Its hard to believe there is no varations in a quad set!  
 
The Here is my input, feel free to comment.  
 
The power amps dependent: (IP) IP is the current measure, right? Power amp with fixed bias mostly come with a rotory switch for fine tuning and output valves with a few ma deviation can be adjusted from time to time to balance current for both sides in the transformer windings. The aim is to match the current between valves, not their grid negative voltage.  
 
(gm) Since the amplication factor is relatively low at the output stage, if excat matched gm cannot be found, a close to less than a few percent apart perhaps would be the least acceptable. More important is matching betwen valves rather than higher gm.  
 
For voltage amplification valves such as X7, U7, 6SN7 etc, the gm is of great importance because the voltage gain is high and mostly affect by gm and ra  
Amplication factor = ra (internal resistance) X gm  
And not many amps have adjustment for voltage gain and driver valves.  
 
 
bobui
11-08-08
11:44:48
回覆 (198): 300B X 4 listening test
 
No problem, John.  
 
limage
11-08-08
11:36:01
回覆 (197): 300B X 4 listening test
Thanks Limage.  
 
They were Gold Lion KT88 reissued matched quads.  
 
The first quad with stickers IP 74 GM 8500 , the second with stickers IP 77 GM 7800 and the last with IP 82 GM 7700 .  
 
I bought the second one because I didn't know which number is more important (so I took the one with mid IP and GM numbers) .
jcml
11-08-08
11:02:13
回覆 (196): 300B X 4 listening test
 
 
jcml,  
 
Provided the seller is honest, higher numbers are better and yet too high may sometimes spell trouble. For a quad set,  
if all four indicate comparable high scores, you can't go wrong.  
 
limage
11-08-08
10:09:51
回覆 (199): Ordering parts from Mouser
mdlover,  
 
Thanks for the great found. Please check PM.
icefox
11-08-08
01:01:12
回覆 (198): Ordering parts from Mouser
just did a quick search, it's available from farnell as well,  
 
cheaper too.  
 
of coz you are always welcome to add your stuff to my order........  
http://hk.element14.com/texas-instruments/rc4559p/ic-op-amp-dual-pdip8/dp/1459652?Ntt=rc4559
mdlover
11-08-07
23:59:35
回覆 (197): Ordering parts from Mouser
icefox,  
 
are you in a hurry?  
 
i regularly order from either digikey or mouser, if you can wait, i can include your stuff into my next order.
mdlover
11-08-07
23:51:25
回覆 (196): Ordering parts from Mouser
Hi Fellow DIY experts,  
 
I need to order some ICs (RC4559), I found that Mouser stock it. However, the number I required is not huge, probably 2pcs or so. The shipping cost lists is HK$160, way more than the components itself. I saw that they are having a promo for order more than HK$750, they can wavie the delivery charges.  
 
Here is my questions,  
 
1. Can I ask to collect the ordered items from their HK office in Kowloon Bay?  
2. If not, any of you guys going to have sizable order from Mouser and I can tag along?  
3. Do you know of any place like in Ap Liu St or Mong Kok that would stock this IC and sell retail?  
 
Thanks.
http://hk.mouser.com/ProductDetail/Texas-Instruments/RC4559P/?qs=sGAEpiMZZMtCHixnSjNA6P3Ssczg4flJ1KBs5qXCQ3w%3d
icefox
11-08-07
23:31:17
回覆 (195): 300B X 4 listening test
Buy matched quad with IP and Gm numbers printed outside the boxes.  
 
How to choose ? Are those with bigger numbers better or power amps dependent?
jcml
11-08-07
22:01:57
回覆 (194): 300B X 4 listening test
hi Thomas,  
Is a real achieivment to produce an amp from scratch to finish. I kind of know it well simply because I am also a DIY. As said, you already have a fine creation and I am sure you know better how to master it to perfection.  
 
I do find that there are some very experienced high hands here in this site and I wish I can meet you alls soon to share and blow water!  
 
Yes, the Viac 30B are fairly new and I happen to have six, not quad, perhaps that would be a better reason to meet when time is right!
bobui
11-08-07
20:51:54
回覆 (193): 300B X 4 listening test
"""Ck=1/2X3.14 X1X0.25= 630uF...""  
 
 
My calculation of the cathode cap cut off point is more or less the same as yours. The point is I won't aim at 1Hz cut off at the expense of introducing unnecessarily high capacitance anywhere into the circuit. There are always pros and cons.
ThomasC2
11-08-07
20:40:41
回覆 (193): 300B X 4 listening test
trust test scores than brand  
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Hey, long time no talk. How are you? I was so eager to take my girlfriend/bike for a ride under the burning sun on Sat that I kind of regret to have missed the laughter, the many high hands and good food on 星期六茶聚. Oh, thats bad, real bad! bike or hi fi, hi fi or bike. Popeye got it so well balanced, I am learning la!  
 
Yes, you are right! You are so right! Is a must have and never too late, a good valve tester can save life.  
 
I kind of only realise the importance of well matched valves in the last few years and I regret for spending lots of my pocket money on valves without checking their "Conditions" before and at purchase. I now have an AVO CT160 and a self made tester with the option to inject AC signal from a sig-gen to test gm and internal resistance.  
 
Look forward to seeing you soon. Oh, my 811-10 is under way. No more talking needed!  
 
bobui
11-08-07
20:31:14
回覆 (192): 300B X 4 listening test
 
 
RCA 6B4G/2A3 way more clear sounding than the Emission 300Bs  
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Do you have a good tube tester, bobui?  
 
I’d rather trust test scores than brand names and/or tube types. KT-88 should, for instance, beat 6550 in every respect,  
but I’ve found good operating 6550 could easily come off totally unabashed on listening tests.  
 
limage
11-08-07
19:20:41
回覆 (191): 300B X 4 listening test
yes, thats right! 6 of these little creatures could not be sufficient to exchange for one single WE orginal 300B, probably not even the newly (90's) made WE300B. To bad, too bad! Too poor indeed! Four of these little creatures will be pluged in to replace the Emissions next week. Share with you more on my very subject test.  
 
A Poor man show off time! Forgive!  
bobui
11-08-07
19:02:53
回覆 (190): 300B X 4 listening test
Here is what i did over the weekend apart from start soldering the power supply parts on my 811-10 ppp project which I feel shame to show photos at this stage. Trust me! Its a mess right now!  
 
I plug in what begin to be a long listening test to the very small collections of 300B i have.  
 
Sorry to have to disappoint some here but in terms of overall performance, The RCA 6B4G/2A3 way more clear sounding than the Emission 300Bs. Photos of WE, Vaic and Svetlana coming real soon.  
 
bobui
11-08-07
18:43:13
回覆 (189): 300B X 3 parallel SET full DIY amp
Hi Thomas,  
 
Seem like you already have attracted a lot of responses here and on the other site! Your workmanship to me is well preapared and construct. Congrat! Cant think of any further input. Please find below equation I've learned from Radiotron Desginer's handbook, the late HK Bush Mr Chan Notes and Morgan Jones writing.  
 
Just pure sharing, hope you find it useful or simplly ignore if you already have other thoughts.  
 
First Stage DET20 Cathode Decoupling: The calcualte is based on Rk and the cathode resistance of the valve.  
 
From the valve:  
rk=RL+ra/u+1  
rk=16.6+6.6/20+1  
rk=1.1k  
 
Together with the parallel 330ohm cathode resistor, the total resistance r'k is 250ohms  
 
For a 1Hz frequency cut off:  
Ck=1/2X3.14 X1X0.25= 630uF  
 
The first stage is of most important because there will be a number of stages, each with filters, so its cumulative.  
 
Just a very rough calcualation, a 1k resistance r'k, you need 170uF for a 1Hz cut off. Perhaps, you may want to consider increase the bypass 100uF at the Cathode of DET20 to a higher value.  
 
Correct me if i am wrong. To me, sharing is always prefered than screaming.  
 
 
 
bobui
11-08-07
17:54:40
回覆 (188): 300B X 3 parallel SET full DIY amp
Dear DearAbby,  
 
So you are ttvfwong on that side?  
 
""""...Analytical, and perhaps a bit too bright for some kinds of music....""  
 
Actually what I had intended to say was "Analytical with tons of details, and perhaps a bit too bright for some kinds of music but it is just good for the most."  
 
To avoid being arrogant, I dropped those self praising parts of the sentence . So, there actually isn't anything significantly wrong with the sound of these amps.  
 
""" I asked you before how you measured the frequency response. If it is 20 - 20k at +/- 1dB, the sound cannot be "a bit too bright..""  
 
Yes, you did, and I have answered as well.  
 
Technicalities such as the working points including the bias level, value of each part used, resulting cut off points etc. can all be calculated and/or measured. For my amps, these have all been duly calculated and/or measured, and further checked at your suggestion.  
 
I see no reason to cast too much doubt on the reliability of the formulae and equipment I have used even though I have also said that my sig gen etc. is probably not up to standard.  
 
Having said the above, I would be more than happy to try some other caps of different kinds or different value. However, I believe I will be doing that for some improvement, if there can be any, but not correction of any error.  
 
Anyhow, thanks again for your valuable comments and encouragement.
ThomasC2
11-08-06
21:36:04
回覆 (187): 300B X 3 parallel SET full DIY amp
... perhaps a bit too bright for some kinds of music. Might need some more time to burn in or replacement of the $3 each coupling caps I am now using.  
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Dear Thomas  
(A bit) too bright .. is to be expected as I commented before - the values of all the coupling caps are too low. The low frequency response is governed by the time constant of the coupling CR. It won't help you at all by burn-in, or by replacing them with more expensive caps. The danger is once you follow a wrong concept to look for "better cap" (in terms of make or price), you will lose the opportunity to develop your skills to achieve good sound by focusing on engineering accuracy.  
 
Similarly, I asked you before how you measured the frequency response. If it is 20 - 20k at +/- 1dB, the sound cannot be "a bit too bright".  
 
I think your circuit config is good and the workmanship is super. There is a chance for this amp to be a killer. Be prepared to spend a hundred hour (or more) to voice it and your payback will be really handsome.
DearAbby
11-08-06
11:11:11
回覆 (187): 300B X 3 parallel SET full DIY amp
Thanks for sharing! I am sure you know how to get the sound you looking for after a few minor modifications!  
 
Unfortunate Mr Chan at HK Bush left us behind earlier, some of my transformers were either tailor made by one of his close friend which no longer make transformer or special order from Tango. Earlier days, Chan taught me a lot about the importance of the power supply in an amp, it's the first and only active component!  
 
My Tango MCT-999 were special order by Mr Chan over 10 years back at no than HK$3,000 and still is my favorite!
bobui
11-08-03
21:39:07
回覆 (186): 300B X 3 parallel SET full DIY amp
"""How do you like the sound? As expected?""  
 
Analytical, and perhaps a bit too bright for some kinds of music. Might need some more time to burn in or replacement of the $3 each coupling caps I am now using.  
 
For power transformer, why not just go to Po Shan in To Kwa Wan and have one custom made according exactly to what you need. However, the power rating of their transformers is very aggressive. Just order a 500VA type if you need 200VA and it should be fine.
ThomasC2
11-08-03
20:23:32
回覆 (185): 300B X 3 parallel SET full DIY amp
i don't think the transformer cares what kind of rectification you are going to use^-^
drwkng
11-08-03
18:08:50
回覆 (184): 300B X 3 parallel SET full DIY amp
bridge Iac = Idc X 1.61.  
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ok, ok, I am sure you all know the above equation well as we mostly use capacitor choke capacitor filter.  
 
For Choke inout filter the equation is: Iac = Idc X 1.06. Less lost in current but then the dc voltage would be lower as a trade in.  
 
bobui
11-08-03
17:04:46
回覆 (183): 300B X 3 parallel SET full DIY amp
that i don't understand.  
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God, you read fast!  
 
I dont understand either. The shop owner seems to have got the wrong idea that after a bridge solid state recitifer, you can still get the max current as written in cow. I didnt care to explain the equation to him that in bridge Iac = Idc X 1.61. He is a qualified enginneer, anyway!  
 
bobui
11-08-03
16:58:07
回覆 (182): 300B X 3 parallel SET full DIY amp
. He said is 250ma written on the cow, so you can get 250ma! I replied trying to tell him that the cow is not a full wave and need a bridge solid state, you will not get the full 250ma!  
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that i don't understand.
drwkng
11-08-03
16:43:51
回覆 (181): 300B X 3 parallel SET full DIY amp
Thanks for the encouragement,  
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Sometimes, the simpliest is the best! How do you like the sound? As expected? let us know your feedback here please.  
 
I've just started on a new project, Svetlana 811-10 PPP. You did make some contributions to my initial design here a few weeks back? Didn't you? Thanks anyway.  
 
Speaking of transformer - I think I should start learning how to make my own.  
I went with a friend to Mong Kok 2 months ago to look for power transformers for my 811 project. I told one shop owner I need a 500V cow or above in secondary. He went to search hard and show me one with 600V and suggest that if use with solid state rectifier, i will get 700dcV. I asked how he got the 700dcv. He replied saying is roughly 1.2 X 600V and then kept on telling me to trust him and he is a qualified engineer!  
 
What more is that when I asked him the output current. He said is 250ma written on the cow, so you can get 250ma! I replied trying to tell him that the cow is not a full wave and need a bridge solid state, you will not get the full 250ma! He went on and on a again and insist that I just need to trust him and he is a qualified engineer!  
 
I like the shop owner. He really has tried hard to look for a cow I was asking. He is always ready to serve and mostly carry a smile but that day we didnt do business.  
 
Vac = Vdc x 0.71  
 
Iac = Idc x 1.61  
 
 
 
 
 
 
bobui
11-08-03
16:37:39
回覆 (180): 300B X 3 parallel SET full DIY amp
"""Nice DIY work!""  
 
Thanks for the encouragement,  
 
"""Are you using your own trans?"""  
 
Yes. From initial designing, material picking, calculation, machine rolling.....all done by myself. Take a look at here if you are interested in knowing more about the transformers. http://hk.myblog.yahoo.com/jw!aDpjOTKGE0Xz_lhz9EEe9A--
ThomasC2
11-08-02
20:27:49
回覆 (179): 300B X 3 parallel SET full DIY amp
Some basic testing results. Quite presentable, I believe.  
 
輸出 : 25W (削波前10V rms 於4 Ohm 負載)  
 
頻應 : 於 1W輸出時, 20Hz – 20KHz 正/負少於 1 dB  
 
失真 : 於 1KHz, 1W 輸出時 THD 0.2%  
 
於 20W 輸出時1.4 %  
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Thomas, that's not only presentable. An achievement I would say as there's no NFB. Are you using your own trans?
Derek2A3
11-08-02
19:39:38
回覆 (179): 300B X 3 parallel SET full DIY amp
Have been listening to these newly completed amps for about 20 hours.  
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Congratulatons! Nice DIY work!
bobui
11-08-02
14:30:37
回覆 (178): 300B X 3 parallel SET full DIY amp
Some basic testing results. Quite presentable, I believe.  
 
輸出 : 25W (削波前10V rms 於4 Ohm 負載)  
 
頻應 : 於 1W輸出時, 20Hz – 20KHz 正/負少於 1 dB  
 
失真 : 於 1KHz, 1W 輸出時 THD 0.2%  
 
於 20W 輸出時1.4 %  
 
ThomasC2
11-08-02
11:26:49
回覆 (177): 300B X 3 parallel SET full DIY amp
..
ThomasC2
11-08-02
11:19:08