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回覆 (126): Stock up for a party coming!
Some manufacturers disclose output impedance in their spec. Typically a few K or below for modern valve design. Traditional circuit design which takes output from let say the anode of a ECC82 or ECC83 have much higher impedance.  
 
My humble experience in phono and preamp DIY is that higher impedance not necessary sound less appealing to me. If I have to descript it in words, I would say many of the older circuits I have tried with relatively higher output impedance sound more relax and smooth.  
 
In reality, I think the impedance matching is not something we need to worry about it too much unless you have very old circuits i.e. 60s classic amp and very new circuits mix in the bunch. However, there is one area where the impedance matching is of fairly big concern and that is cartridge and phono amp or MC transformer.  
 
 
 
bobui
14-06-26
11:54:58
回覆 (125): Stock up for a party coming!
>I rather belief that impedance matching is the key, not necessarily the largest input vs output impedance ratio.<  
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This is an interesting topic that I have yet to get a definite answer. In most modern home use audio equipment, it seems the idea is to have a high input / output impedance ratio; 10X is the minimum, over 20X is better.  
 
However, as I understand, some professional audio equipment use input / output transformers, and the industry standard seems to be 600 Ohm. So, does it mean the input / output impedance ratio in this case is 1:1 ?  
 
If this is the true, why is there a difference in the 2 different scenarios; just because one uses coupling caps, the other use transformers?  
 
thekong
14-06-26
10:01:02
回覆 (124): Stock up for a party coming!
The problem for commercial manufacturers is that they never know what down-steam equipment their customers are going to use, therefore they need to make the output impedance low enough to match with most equipment on the market.  
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Bingo!  
 
Signal loss is sth we couldn't avoid, and it is the final outcome that we are after. I rather belief that impedance matching is the key, not necessarily the largest input vs output impedance ratio. Theory goes pretty well that in case of 1:100 ratio, signal loss is roughly about 1%, BUT nobody mentioned whether that one % is flat or linear. Now, under most circumstances, with a cap output which the impedance do vary with freq, bass loss is going to be more significant compared to the high ie. the receiving end or next stage receives more treble & less bass.
Derek2A3
14-06-26
09:43:49
回覆 (124): Stock up for a party coming!
>I realize that low impedance doesn't seems to promise the missing part in traditional audio circuitry.<  
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So, what are those missing parts in the traditional audio circuitry you are referring to?  
 
If I understand correctly, a low output impedance only promises less lost in signal transfer between the 2 components.  
 
Also, this so call “low output impedance” is always relative to the input impedance of the receiving equipment. So, if your power amp has an input impedance of 1M ohm (yes, I haven’t seen one yet), then there is no problem if your preamp has an output impedance of 10K, or even 50K, ohm.  
 
The problem for commercial manufacturers is that they never know what down-steam equipment their customers are going to use, therefore they need to make the output impedance low enough to match with most equipment on the market.  
 
thekong
14-06-26
08:29:42
回覆 (123): Stock up for a party coming!
 
 
What's wrong with second harmonics ?  
What you should really worry about are high order odd harmonics.
evp1312
14-06-26
08:10:10
回覆 (122): Stock up for a party coming!
My friend, you know what.  
 
There was one time not long ago I actually believed that low impedance is the name of the game. Its the final achievement and ultimate of all! Cathode buffer, SRPP, mu-follower, you name it. Not rocket science in valve schematic la! Soon after some examination and trial, I realize that low impedance doesn't seems to promise the missing part in traditional audio circuitry. Then I thought, could it be my inability to execute properly of the so call low impedance output or what.  
 
To be fair, I really hasn't come up with an answer yet but then what I do know by now is that the bloody distortion some of us once tried so hard to get rid of namely in the 90s happen to be a major part to our GOOD sound in 21st century. Mainly I am referring to second harmonic lor!  
 
To be or not to be!  
 
 
 
bobui
14-06-25
23:34:33
回覆 (121): Stock up for a party coming!
 
 
Well, a valve pre-amp driving a transistor power amp isn't the best way to go, theoretically speaking at least. In terms of matching, the solid state pre-amp is inherently low in output impedance as well as noise level, it would make a perfect match with high impedance input of the valve power amp.  
 
What's more, solid state pre-amps can be left on round the clock making it a very stable program source. You don't have to worry about your wife not observing the turn-on sequence too.  
 
limage
14-06-25
14:31:34
回覆 (120): Stock up for a party coming!
It leaves no room for your diy valves!  
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Let me tell you a secret, my friend. Despite all the wow and wah I constantly rave about some Svetlana 811-3, PX25 or 6B4G based valve amps, I am actually, at heart, a fan of transistor power amp. Particularly the V-fet and select transistors such as the Darlington pair or MJ15003/4 used in old Quad amps.  
 
In fact, my immediate plan after completion of my giant 811-10 PPP and four pairs 6B4G power amps would be some V-fet or transistors class AB power giants.  
 
However, when it comes to phono and preamp. Well, basically any voltage amplifier, I am more incline to valve or tube la.  
 
Voltage----current, preamp----power amp. You know what I mean!  
 
The Meridian M100 is a beauty, right? Fancy a go?  
 
bobui
14-06-25
13:05:28
回覆 (119): Stock up for a party coming!
 
 
The M100 is an active speaker with built-in solid state amps. It leaves no room for your diy valves!  
 
limage
14-06-25
12:28:50
回覆 (118): Stock up for a party coming!
Drinks - Food - Hi Fi. Correct priority?
bobui
14-06-25
10:59:02
回覆 (117): Stock up for a party coming!
 
Forget about the Meridian, we want food ASAP!  
 
thekong
14-06-25
10:46:12
回覆 (116): Stock up for a party coming!
Eight white belly buttons Kef B110 per speaker. Coming in fast. Must wait la!  
 
bobui
14-06-25
10:35:22
回覆 (115): Stock up for a party coming!
No shit! Finishing on various toys for a big occasion. A pair of Meridian M100 on their way to add more fun too!  
 
bobui
14-06-25
10:14:45
回覆 (114): Stock up for a party coming!
 
 
Cut the bulls...  
 
When ? This Sat ?
evp1312
14-06-25
09:50:01
回覆 (114): Stock up for a party coming!
I am ready for it.
Derek2A3
14-06-25
09:48:09
回覆 (113): Stock up for a party coming!
You know what. I fear my message might have fall into an unintentional technical discussion on how valve can achieve a 600 ohms inter-stage output impedance to feed the LCR transformer. So, here is my answer to you:  
 
I have zero interest on how any other LCR base RIAA phono works, being proper or not, far from a matter that concern me lor. All I care is if mine is properly done. More like if I say, I am hungry and must eat. Doesn't imply you have to be hungry to have the need, the desire or urge to stuff yourself with plenty of food down your throat. What I do care is if you are hungry and happen to be coming over to my den to have a good time, it would be my desire to make sure you have something good to eat and best if you also get to have enough for the day or a meal.  
 
bobui
14-06-24
22:29:57
回覆 (112): Stock up for a party coming!
of coz i'd love to :-P  
 
but when you said "proper", it seems that all others are improper? yes? no?
mdlover
14-06-24
22:05:21
回覆 (111): Stock up for a party coming!
You want to come over to check on how a 600ohms in and out LCR phono get done or just getting drunk? Choice is yours!  
 
bobui
14-06-24
22:01:15
回覆 (110): Stock up for a party coming!
And I make sure you get to taste proper execute LCR, 417A/5842 phono, Tango MCT-999, PPP 811-10 etc etc....  
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proper?  
 
are you sure? :-)
mdlover
14-06-24
21:56:19
回覆 (109): Stock up for a party coming!
Make no mistake please. For those who weren't here at my den a little over three years ago, I assure you that the one coming real soon can only be more fun...........with plenty good stuffs.  
 
evp1312, cadiver, wher..............please be patient. I am in process to stock up. Forget about Dom and VC la. Krug... and nothing less la!  
 
And I make sure you get to taste proper execute LCR, 417A/5842 phono, Tango MCT-999, PPP 811-10 etc etc....
bobui
14-06-24
21:35:24
回覆 (108): Live! Czech Philharmonic
Smetana Vltava by Czech Philharmonic. The same program they will be performing in HK in June.  
 
Run for your tickets. I got mine la.  
 
bobui
14-05-05
15:01:28
回覆 (107): Live!
Czech Philharmonic perform music from two of the most famous Czech composers, Smetana, Dvorak.  
 
Get your tickets before its too late. Still a few left for grab.  
 
http://www.lcsd.gov.hk/CE/CulturalService/Programme/en/index.html  
 
Goo luck!  
 
bobui
14-05-05
14:47:15
回覆 (106): Cheap and Cheerful!
A real bargain and almost perfect for phono or preamp. Just that the current is a bit on the low side @66ma. After rectification, I can only get about 42ma (bridge).  
 
They would be prefect fit for my next project, two LCR phonos. Identical circuit but one with Tango LCR and the other with Lundhal LCR.
bobui
14-04-15
10:25:06
回覆 (105): Cheap and Cheerful!
@ three hundreds Hong Kong dollars each.  
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Congratz, that's a steal
Derek2A3
14-04-15
09:24:26
回覆 (104): Cheap and Cheerful!
Got these from bay watch @ three hundreds Hong Kong dollars each.  
 
Parmeko transformer: 250vac X 66ma plus a 6.3v center tap. Primary can connect to 230v.  
 
Perfect for two sets of dual mono LCR phonos.  
 
 
 
bobui
14-04-15
07:31:34
回覆 (103): Brits music
but I think you all like this one better, right?  
 
bobui
14-04-10
11:47:43
回覆 (102): Brits music
Wonderwall - like this one best from Oasis  
 
bobui
14-04-10
11:43:21
回覆 (101): Long time no talk
I am old, I am light on eating fat, when I eat fat, I ended up drinking too much ! But it's good I know ....
Cadiver
14-03-18
03:13:06
回覆 (100): Long time no talk
That must be like a Jadis JA30 equivalent in $$$.  
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Not really. Just like a scruffy and cheapo diy amp. Serrano is the average grade Jamon (ham from spain). Iberico is the finest and can cost as mush as USD700 plus.  
 
Nevertheless, I am having fun with it and taste nice. The fat is full of flavor. Yummy! Worth the diy effort.
bobui
14-03-17
08:32:00
回覆 (99): Long time no talk
Like ah, black toe iberica hamon, anytime. The entire thing ? That must be like a Jadis JA30 equivalent in $$$.
Cadiver
14-03-17
02:45:35
回覆 (98): Long time no talk
Wow! Forget about the diy 6C33, 300B and 6B4g. This is way more satisfying lor! Un-cock two bottles of Bourgogne for the night to serve with the Serrano.  
 
Come if you fancy.  
 
bobui
14-03-16
20:20:21
回覆 (97): Long time no talk
Wha wah wha! How are you guys? Hope all is well and super.  
 
No diy audio for over a month la. Been busy day dreaming of my next bike, the Colnago C60 and what else! Food lor!  
 
Learning the trick to slide cut a whole Serrano. A diy for not the ears but palate!  
 
bobui
14-03-16
20:12:48
回覆 (96): Four hands!
Glad to have met you, Lawrence.  
 
Hungarian Dances No.4. I believe this is the Julius Katchen with Jean Pierre Marty. The other four hands I really like is the Mozart Sonata. Cheerful music!  
 
bobui
14-03-02
11:54:01
回覆 (95): HK$95 only
Yeah, those are junks, don't even think of sending them to me. Time & space are too precious. I only need the bottle together with the contents of course.
Derek2A3
14-02-21
14:48:51
回覆 (94): HK$95 only
These are terrible ugly sounding amps. Shame on me lor! Shouldn't be included in the photos at all. They were there to give easy reference to the size of the bottle only!  
 
In fact, if you buy the bottle, I shall give them away for free just si I can clean up some trashes at home lor! Too bad Derek2A3 got them first! Next time lor!
bobui
14-02-21
13:53:40
回覆 (93): HK$95 only
Can I have the amp instead ?! :-)
Cadiver
14-02-21
13:38:47
回覆 (92): HK$95 only
Just two will do! thanks
Derek2A3
14-02-21
13:26:21
回覆 (91): HK$95 only
Easy la bro! I have just ordered 12 bottles delivered to my den yesterday. How many you want? Can take some to the office tomorrow and pass over to you anytime.  
 
bobui
14-02-21
13:07:22
回覆 (90): HK$95 only
Thanks for the info, but question is where could I get it? pls
Derek2A3
14-02-21
12:38:08
回覆 (89): HK$95 only
No, not the amps!  
 
Amongst the many Prosecco I have tried, this one is best value for money and doesn't taste like sugar water in carbonate bubble water and the price is only HK$95.- per bottle.
bobui
14-02-21
11:54:08
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