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Post by krisno on Mar 29, 2009 19:15:38 GMT
I need help and I need it now...
I am swapping out the output caps on my DAC with some 4.7uf foil obbligato's . Anyways.... I have been recommended to solder the output leg of that output cap directly onto the RCA terminal. That sound's nice, but if I do that I am 'bypassing' that little 47ohm resistor which is there.
I know that my Burson HA-100 and X-can V2 has 47ohm input. If I bypass that 47ohm in the output of the DAC. What will happen? Is impedance matching important or not? Does the 47ohm degrade sound quality and I am better of bypassing it??
K
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Post by Deleted on Mar 29, 2009 20:35:50 GMT
I need help and I need it now... I am swapping out the output caps on my DAC with some 4.7uf foil obbligato's . Anyways.... I have been recommended to solder the output leg of that output cap directly onto the RCA terminal. That sound's nice, but if I do that I am 'bypassing' that little 47ohm resistor which is there. I know that my Burson HA-100 and X-can V2 has 47ohm input. If I bypass that 47ohm in the output of the DAC. What will happen? Is impedance matching important or not? Does the 47ohm degrade sound quality and I am better of bypassing it?? K Leave it alone ! It is there for a couple of damn good reasons! |
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Post by krisno on Mar 29, 2009 20:48:46 GMT
It's not possible for me to leave it alone. I have to in case solder a 47ohm at the end of the one leg of the ouput cap...
And SandyK if I want to do that, I have another problem. Where can I find 2 quality 47ohm resistor? Got a brand name .... must they be 0,5watt or 1watt etc?
K
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XTRProf
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Post by XTRProf on Mar 30, 2009 3:10:29 GMT
That resistor is not so much for impedance matching but can also do some attenuation as well as stabalise the output stage from oscillation. As long as the output is low impedance connected to a high ouptut impedance, the impedance is already matched for the best frequency response and power transfer.
As for resistor, as long as it's already a metal film type, that will be amongst the best that you can get short of the metal foil. The latter can be very expensive. If you can affod the metal foil try Vishay. The sound will generally up one or 2 notches. 1/2 W will be more than enough for signal output.
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Post by krisno on Mar 30, 2009 13:26:55 GMT
The input of both my X-can V2 and Burson HA-100 is said to be 47k ohm.... Do I need a 47k ohm resistor output on that dac at all then? I am using Obbligato Premium output caps... they won't work as a resistor by themself? My dac shows 47Kx2 it says written beside the 2 output resistors... I need replacement for these. www.hificollective.co.uk/components/holco_resistors.htmlI look at that pages, Holco seems cheap and its 'film'.. But I don't understand which one I should get. Do I look at the K rating or the R rating? If someone can find the one and paste in the spec under here I would be happy. Thanks guys! K |
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Post by krisno on Mar 30, 2009 19:23:29 GMT
I ended up with 47K ohm tantalum resisors, £2.80 each...(audio note).. We will see. I thought I could be without resistors, but people somehow say they are there for a reason. Also the meridian cdplayers have 47k ohm resistors so why not me to..
question nr two will be if I destroy this DAC when soldering on it. Whish me luck, cya in a weeks time..
K
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Post by PinkFloyd on Mar 30, 2009 21:59:10 GMT
I ended up with 47K ohm tantalum resisors, £2.80 each...(audio note).. We will see. I thought I could be without resistors, but people somehow say they are there for a reason. Also the meridian cdplayers have 47k ohm resistors so why not me to.. question nr two will be if I destroy this DAC when soldering on it. Whish me luck, cya in a weeks time.. K Do you ever LISTEN to good advice or are you simply an idiot? |
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Post by krisno on Mar 31, 2009 8:40:20 GMT
Mike.. what you mean? What advice? They didn't sell Vishay and the guy in the shop said the Audio Note tantalum where the best...
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Post by Deleted on Mar 31, 2009 9:03:38 GMT
Why ?  If they are between the output RCA and earth, their purpose in life is to pull down the output jack side of the capacitor to an earth potential, so as to avoid loud clicks in the preamplifier/amplifier. Their influence on sound quality would be absolutely minimal as they are not in the direct sound path. IMO,you have wasted your money. SandyK |
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Post by krisno on Mar 31, 2009 9:16:32 GMT
The thing is that I have to bypass them to be able to fit these 5cm*3cm output cap's I believe. .
Well I might have, but you guys answer so slow... You are not nice people actually. hehe.
Good thing the UK is going down the drain then, the sterling is cheap. But the guy actually recommened these. I thought I could solder them directly on the output cap 'leg' and then directly on the RCA. Making the signal path as short as possible.
K
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Post by Deleted on Mar 31, 2009 9:25:40 GMT
Krisno We answer so slow, because you mostly ask the same questions over and over , and over again,then usually ignore the advice given anyway.  Besides which , one moment you are talking about 47 ohm input (which is wrong) and 47 ohm output resistors, then in the next breath you are talking about 47K ohm resistors.  Sandyk |
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Post by krisno on Mar 31, 2009 9:46:09 GMT
I just cancelled the order.. have a look then my friend. Look at this picture..  Do you see those Russian tantalum's there. I am giong to replace them with som Obbligato 4.7uf film caps. I thought that I would bypass the rest of the board by soldering the output leg of the obbligato's directly onto the RCA. But then I would omit those 47K resistors. That's why I orderd some tantalum resistors 47k ohm so solder on the output lead on the obbligato's and then onto the RCA terminal. Was this wrong thinking?? People say that the music sounds a little 'thinner' when including those resisors.... Give me your 5cent on this. |
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Post by Deleted on Mar 31, 2009 10:18:51 GMT
Krisno
They are 47,000 ohms and APPEAR to be connected from the output side of the capacitor to earth, but I can't be certain from the photo. You could solder the new resistors directly across the RCA sockets. As I said previously , quality is relatively unimportant at that location. You could have used a 5 cent metal film resistor, and most likely would have been unable to notice any difference.
SandyK
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Post by krisno on Mar 31, 2009 10:27:44 GMT
Thanks m8ie..
I have cancelled the order, so don't worry. I will just solder the obbligato's directly in the sockets replacing the russian output caps.
But what you mean by solder the new resistors diretly 'across' the RCA's? Do they work in paralell of the output cap and not in serial like I thought? ....
How do you solder it 'across' the RCA? across both rca's...?
Thanks!! I do take your advice. That's why I got the X-can V2. Thats why I got the mod and little pinkie...
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Post by Deleted on Mar 31, 2009 10:59:59 GMT
Krisno
The capacitor connects from the output stage to the inner (active of the RCA socket. The sleeve (outer) of the RCA socket goes back to the earth (0 volts) of the circuit board. Soldering the resistor directly across the RCA output socket will provide a high resistance from the outgoing side of the capacitor to earth.
This means there will be 2 wires connected to the inner (active) terminal of the RCA socket. (one side of the capacitor,and one side of the 47K ohm resistor.)
SandyK
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Post by krisno on Mar 31, 2009 11:25:39 GMT
So it works in parallel.. I won't replace any of it. Just replace those tantalum's with the obbligato's directly.
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Post by krisno on Mar 31, 2009 15:34:52 GMT
Thanks for saving me for those £15 ... !! You are the best.
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leo
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Post by leo on Mar 31, 2009 17:32:12 GMT
Krisno We answer so slow, because you mostly ask the same questions over and over , and over again,then usually ignore the advice given anyway. Besides which , one moment you are talking about 47 ohm input (which is wrong) and 47 ohm output resistors, then in the next breath you are talking about 47K ohm resistors. Sandyk I think Kris has a dark humour? hopefully I'm right unless he's just really pig headed ;D  Anyway, I agree , be easiest just to solder the 47k's across the phono sockets and hardwire the big film cap from the I/V stage to the phono sockets + |
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Post by krisno on Mar 31, 2009 17:53:29 GMT
Why do you say this Leo. Sandy'k just said the resistor was not worth using... now you say its better to solder them across and then solder directly.. ?
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leo
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Post by leo on Mar 31, 2009 18:48:31 GMT
Just wire one end of the new cap to the active circuit and the other end to the socket leaving the wires on the sockets too
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Post by leo on Mar 31, 2009 19:09:42 GMT
The wires go to the 47k resistor which go to ground so leaving the wires on you don't need new resistors I don't think theres any more resistors in series with the caps to output, I think theres only the 47k resistors output to ground We need a biiger picture to be sure Make sure if your wiring direct to the phono sockets you solder the other end of the cap into the right pcb hole It should be marked as + on the pcb, I may have drawn wrong hole, I can't see clear enough from the picture so had to guess  |
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Post by krisno on Mar 31, 2009 19:15:51 GMT
Thanks leo.. I don't know if there is a + marked on there. I will remove those Kemet 10uf caps you know. By pluss, you mean the PCB hole which gets the current from the ferrite beads yes? ..
Leaving the cables on, removes the need for the ohm resistor, but won't it cause interference or something else nasty? Is that the best thing to do.. or I just replace the Kemet fully, but installing the new output caps just in their socket...
What would you do?
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leo
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Post by leo on Mar 31, 2009 19:27:39 GMT
There might be just a square mark on the drawing which shows the plus side If you look at the top of where its marked 5600pf on the pcb, you can see little squares marked on the capacitors drawing? if theres no little squares marked on the other sides then that may mean + The wires to the sockets is only short so it shouldn't cause any problems, its almost the same as adding metal film resistors there anyway If you remove the Kemet capacitors, can you fit the new caps in the same place? if so I'd fit them there, you can then totally forget the above  , you should be able to bend and form the legs of the new capacitors so they fit in the holes Just make sure the legs don't short out on anything Are the new capacitors very large? |
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Post by leo on Mar 31, 2009 19:34:58 GMT
BTW, you can tell which is the pos +v side of an axial tan cap, if you look at the end there should be a plastic ring around the soldered leg, the negative leg -v side is attached to the metal case
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Post by krisno on Mar 31, 2009 21:28:05 GMT
The PCB has 2 squares which you see on the picture, on the other side the 'squares' are round, and not square anymore. That indicate minus? But the RCA's are they 'minus' then?
I did not understnad your last post..
Yes the caps are big... 5.5cm * 3centimeter.. I might have to unscrew the board just to see where the signal is passing, then I can confirm it.
I am sure the sound will be better by directly soldering the output cap leg onto the RCA instead of onto the PCB board again. I will keep the wires on then, so I get that 47kohm resistor. Are you 100% sure of this....
But the current moves from + pole to - pole.... so the way it goes through the Keces is actually from the dac chips through the 'square' +pole and to the -(round marking) pole, and then to the RCA's??? IS that how the current flows?
K
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Besides which , one moment you are talking about 47 ohm input (which is wrong) and 47 ohm output resistors, then in the next breath you are talking about 47K ohm resistors. 
, you should be able to bend and form the legs of the new capacitors so they fit in the holes