# recommended quality DIP8 dual op. amplifier over NJM4558...?



## trodas

In a mediocre old Genius SW-5.1 Home Theather ( http://www.dzikie.net/artykuly/genius_sw51_ht/18.jpg ) are used on the AC3 input a four pieces of JRC 4558D dual operational amplifiers.

 Datasheet there: JRC4559 datasheet pdf datenblatt - New Japan Radio - DUAL OPERATIONAL AMPLIFIER¡¡ ::: ALLDATASHEET :::

 They are in DIP8 packaging and these SW-5.1 are connected to my X-Fi. Somewhat long time ago I saw a thread about replacing these aplifiers for better ones, but I can't find it anymore. And as time go, it is probably possible to find better - compatible - ones now, right?

 Operating voltage is from +/- 4 to +/- 18V, high voltage gain - typically 100 dB and high input resistance - typically 5 Mohms. (wow)

 What is the best replacement I can use there?


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## ericj

AC3 is by definition digital, and it's receiver parts wouldn't be opamps. perhaps you mean the analog 6-channel input. 

 at any rate, chances are that they are used in an ac-coupled, closed-loop circuit, which means you can use just about any dual opamp. 

 opa2134, for example. probably lm4562. 

 before trying chips with significantly lower power supply tolerance, like AD chips, find out what the power supply voltage actually is across the chips on the board. you'll need to get in there with a volt meter while it's powered up, probably.


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## trodas

Oh, yes, I should mention the "little detail" that the AC3 input - or output from the soundcard - is analog one.

 How to I check what circuit it is?

 To me it looks like as that input is decoupled by 10uF 25V CapXon cap - 6 of them - (grrr, what a... ) and then there are the 4 opamps and another 6 pieces of 10uF 25V...
 Perhaps shorting them all will make the sound more detailed, as there is something better that cap - a wire 
	

	
	
		
		

		
			





  Quote:


 opa2134, for example. probably lm4562. 
 

LM4562? The very same opamps as used in the X-Fi mods?
 Should be beneficial to use twice the very same opamps - I mean LM4562 in X-Fi and in the subwoofer as well?

  Quote:


 find out what the power supply voltage actually is across the chips on the board. you'll need to get in there with a volt meter while it's powered up, probably. 
 

Well, I could ask Genius for scheme, but I dubt I getting any. So okay, I try to measure the voltage on them tomorrow. Regardless, I think the design suxx. Not only the output caps after the opamps seems to have too little capacity for my taste (especially for the subwoofer channel) but there is also no ceramic caps close to the pins 4 and 8 where the circuit get supplied - and + voltages respectively. I think that adding like a 1 - 10uF ceramic caps between these legs and ground should be beneficial to the opamp output quality, right?


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## AudioCats

AD8599 can be a good option too.


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## holland

Quote:


  Originally Posted by *trodas* /img/forum/go_quote.gif 
_*How to I check what circuit it is?*_

 

 Quote:


  Originally Posted by *trodas* /img/forum/go_quote.gif 
_*Regardless, I think the design suxx.* Not only the output caps after the opamps seems to have *too little capacity for my taste* (especially for the subwoofer channel) but there is also no ceramic caps close to the pins 4 and 8 where the circuit get supplied - and + voltages respectively. I think that adding like a 1 - 10uF ceramic caps between these legs and ground should be beneficial to the opamp output quality, right?_

 

How about spending some time figuring out the circuit before you change things without knowing what they do?


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## trodas

*AudioCats* - thank you for your suggestion. Are there some reasons to prefer AD8599 over LM4562?
 And what if my X-Fi already having LM4562 - is this a reason why use the same opamps in the speakers, or not at all? Could be usage of the same same chips beneficial?


*holland* -  Quote:


 How about spending some time figuring out the circuit before you change things without knowing what they do? 
 





 ...but...
 You are right 
	

	
	
		
		

		
		
	


	




 I go and ask Genius to supply me the scheme of the SW-5.1 Home Theather - but I think they probably never reply, or hit me with some classis BS reasons why I cannot see it.
 Nevermind. What is known is, that this is the top PCB on my speakers and that there is where the 6 channels go 
	

	
	
		
		

		
		
	


	




 First they get thru a kinda high resistance, then there is a desoupling capacitor and then they pass thru the four Opamps. Looks like the usage of the subwoofer one did differ, tough.

 However, back to the first thing I discover today and that is the voltages. The upper PCB is obviously supplied by this connector:



 



 As you can see, it promise +5V, -12V and +12V. The black wire is connected with the ground, so I started with it and measured - and - whoa!

 On the from left first yellow wire is nice +5.01V. However the red line just after it is at +15.7V! Then the blue wire is -12.54V and black is ground. Red line after it is +11.95V and the yellow line after is -0.2mV - so probably not connected right now to anything.

 What IS interesting is the 0.59V difference between the + and - 12V lines.
 Is this good or acceptable for audio? For the poor opamps?
 Or does this matter?

 Nevermind. I continued measuring, first the there opamps in a row. All have on the pin 8 the + 11.96V and on the pin 4 the -12.55V. (IC6, 7 and 8)





 But IC9 (the bottom one) is a bit of surprise. The pin 8 have the 15.8V (ah, there it goes!), while pin 4 is not connected to anything beside ground. I suspect this is the subwoofer channel only.



 

 

 





 BA6208 is a Reversible motor driver 
	

	
	
		
		

		
		
	


	



BA6208 pdf, BA6208 description, BA6208 datasheets, BA6208 view ::: ALLDATASHEET :::


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## holland

Are those the input jacks below IC9?

 By figuring out the circuit, I meant following the traces and putting together a schematic, by hand, so you can see and analyze it. In other words, reverse engineer it. I don't expect any manufacturer to release a schematic. From there you can see how the opamp loops are closed.

 What's the other circuit board beneath, the green one.

 opamps don't have enough power to drive speakers. I actually expected some monolithic chip amps to do the work, but if they really are using the opamps, it would be for voltage gain with a sizeable current buffer later (i.e., power transistors).

 From a quick google your speaker has an amplifier that puts out 15W into the satellites and center channel and 45W into the subwoofer. No opamp can put that out.

 I would follow the circuit from input all the way to the speaker leads.


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## trodas

Quote:


 Are those the input jacks below IC9? 
 

No, they are the volume potenciometers for surround, center and subwoofer.

  Quote:


 By figuring out the circuit, I meant following the traces and putting together a schematic, by hand, so you can see and analyze it. In other words, reverse engineer it. I don't expect any manufacturer to release a schematic. From there you can see how the opamp loops are closed. 
 

Well, I did not expect, but... look! Miracle happend and they send me Genius SW-HF5.1 schematic:
RapidShare: 1-Click Webhosting





 However the HF ones are slightly different from the SW-5.1 HT ones... But most things match just perfectly.

  Quote:


 What's the other circuit board beneath, the green one. 
 

The input switches and few IO as well 
	

	
	
		
		

		
		
	


	




 I include pictures later...

  Quote:


 opamps don't have enough power to drive speakers. I actually expected some monolithic chip amps to do the work, but if they really are using the opamps, it would be for voltage gain with a sizeable current buffer later (i.e., power transistors).

 From a quick google your speaker has an amplifier that puts out 15W into the satellites and center channel and 45W into the subwoofer. No opamp can put that out. 
 

Of course I know that, don't expect me to be complete beginner. I already looked on the 4 PCB boards and written all caps for recap down, and made few observations about other components there as well:

 Genius SW-5.1 Home Theater caps list:

  Code:


```
[left]enius SW-5.1 Home Threather speakers ------------------------------------- Su'scon & CapXon caps Potenciometer Soundwell B503 - 50kOhm Bx6 with motor RF-330TA 09550 front audio IN, top pannel -------------------------- C64 - 0.1uF 50V d5 C52 - 1uF 25V d5 C86 - 220uF 25V d8 C87 - 220uF 25V d8 C10 - 10uF 25V d5 (A) C9 - 10uF 25V d5 (A) C36 - 10uF 25V d5 (A) C35 - 10uF 25V d5 (A) C62 - 10uF 25V d5 (A) C61 - 10uF 25V d5 (A) C4 - 10uF 25V d5 (A) C3 - 10uF 25V d5 (A) C30 - 10uF 25V d5 (A) C29 - 10uF 25V d5 (A) C56 - 10uF 25V d5 (A) C55 - 10uF 25V d5 (A) front audio IN, bottom pannel ----------------------------- C7 - 1uF 50V d5 C79 - 0.1uF 50V d5 C105 - 100uF 10V d5 C82 - 100uF 16V d5 C111 - 220uF 16V d6.3 ******************************************************************** 3x 220uF Samxon GK 25V d6.3 2x 100uF 16V Samxon RS d6.3 12x Elna RFS 22uF 25V d5 ( 604-1051-ND ) 2x 0.1uF 50V Panasonic KG d4 ( P925-ND ) 2x 1uF 50V Samxon RL d5 ******************************************************************** 4x opamps 4558D ( http://www.alldatasheet.com/datasheet-pdf/pdf/7457/NJRC/JRC4559.html ) JRC ( DIP8 ) 3057K ( NJM4558 ) back PSU/AMP section, right plate --------------------------------- C20 - 10uF 25V d5 (A) C21 - 10uF 25V d5 (A) C37 - 4700uF 35V d18 (19V on it) C39 - 4700uF 35V d18 (19V on it) C13 - 10uF 25V d5 (A) C14 - 10uF 25V d5 (A) C26 - 0.1uF 50V d5 Amplifiers 2x TDA7269A, C20, 21 and C13, 14 connected to pins 7 (L channel IN) and 11 (R channel IN) ( http://www.alldatasheet.com/datasheet-pdf/pdf/25092/STMICROELECTRONICS/TDA7269A.html ) back PSU/AMP section, left plate -------------------------------- C47 - 1000uF 16V d10 C48 - 1000uF 16V d10 C112 - 1000uF 10V d10 C69 - 470uF 10V d8 C75 - 10uF 25V d5 (A) C67 - 0.47uF 50V d5 (A?) - Panny KG 0.47uF 50V ( P929-ND ) C72 - 22uF 25V d5 (A) C70 - 22uF 25V d5 (A) C51 - 470uF 25V d10 C41 - 4700uF 35V d18 (29V on it) C42 - 4700uF 35V d18 (29V on it) C49 - 10 000uF 25V d18 (16V on it) C68 - 10uF 25V d5 (A?) C11 - 470uF 16V d8 C5 - 0.22uF 50V d5 (A???) C6 - 0.22uF 50V d5 (A???) C31 - 10uF 25V d5 (A?) Amplifiers TDA7360 and TDA7286 (?!) ( http://www.alldatasheet.com/datasheet-pdf/pdf/25143/STMICROELECTRONICS/TDA7360.html http://www.alldatasheet.com/datasheet-pdf/pdf/25101/STMICROELECTRONICS/TDA7286.html ) TDA7360 - pin 1 and 5 are inputs - caps C5/C6 connected to them???[/left]
```

 Quote:


 I would follow the circuit from input all the way to the speaker leads. 
 

I tried. Not an easy task, because there is so many caps 
	

	
	
		
		

		
		
	


	




 I think I want remove most of them, if not all 
	

	
	
		
		

		
		
	


	




 Just like on my X-Fi


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## trodas

Whooo! Hooray! I recieved from Genius the correct schematics, so, here we go - Genius SW-5.1 Home Theater schematics: RapidShare: 1-Click Webhosting





 Finally the caps and stuff match. Now I have countless questions 
	

	
	
		
		

		
		
	


	




 There is IMHO too many caps in the audio path. There is decoupling caps on the input of the opamps, on the output and then in the input of the aplifiers at end.

 So, there are some ways to modify these speakers.

 1 - conservative - just replace all the caps used for audio with audio grade caps (like Elna RFS 22uF 25V) and replace the opamps to LM4562

 2 - medium mod - remove and short the decoupling caps on opamps in/out and use udio grade caps on the amps input as the only one caps in the audio path - and of course replace the opamps to LM4562 and add a 10uF 16V ceramic caps on each of their voltage - and + legs

 3 - hardcore mod - remove and short all the decoupling audio caps, replace opamps to LM4562, tweak the resistors fix DC offset to be nearly none and add a 10uF 16V ceramic caps on each of their voltage - and + legs of the opamps, and probably remove the other small ceramic caps as well from the audio path... 
	

	
	
		
		

		
		
	


	







 What do you think, guys?


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## Pars

What do I think? Rapidshare absolutely sucks for hosting!

 Otherwise, I would agree that that thing uses alot of caps in the output stage. I would definitely try to get rid of some of them, but first I would probably go along the audio path and measure the DC offset along it to see how much work removing caps might entail.

 Given what it is, the most rational approach would probably be the first one, maybe not even replacing caps.


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## AudioCats

Quote:


  Originally Posted by *trodas* /img/forum/go_quote.gif 
_*AudioCats* Are there some reasons to prefer AD8599 over LM4562?_

 

check out the opamp testing in the 001 mod thread (there is a link in my sig). The 4562's did not impress me. Of course my test was done in a baby stax amp, the chips might work differently in your system....
 8599 is SOIC only, so you will probably have to make a SOIC/DIP adaptor if you want to use it.


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## majkel

What to say? Both OPA2134 and especially LM4562 are total sonic crap. AD8599 is a great and safe idea. If I were sure no oscillations would occur, AD8022 is another option. Other great sounding bipolar op-amps are single, sorry.


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## trodas

*Pars* -  Quote:


 What do I think? Rapidshare absolutely sucks for hosting! 
 

Well, it is used for most of the hosting I ever saw concerning bigger files, so, suggest alternative 
	

	
	
		
		

		
		
	


	




 Or better not and let's concentrate on the subject 
	

	
	
		
		

		
		
	


	




  Quote:


 I would agree that that thing uses alot of caps in the output stage 
 

I hope this is typo and you mean the input stage. And yes, there is overhelming number of caps. Let's look at this:






 Inputs switching:




 Did not do the deblocking caps blur the audio a little? I mean these C99 - C104. I think removing them will only help. Also I think that it is brain-dead first lower the signal 1/9 (the R129 / R135 divider, 1k / 10k) and then pass it thru the switcher as then any inperfect contact in the switcher play major role in audio quality and since the switcher is general use crap and there is vibrations... I think this is a bad idea. I probably can get rid of this by hard-soldering the switcher connectors in the AC3 input position.

 Remote control and electric motor for volume scheme - nothing interesting anyway:




 Complete audio scheme of the Genius SW-5.1 HT




 Now this is the most interesting stuff.

 As anyone can see, each input is, once again (?!) blocked to the ground with another cap, a C1 for example. Then decoupled of any possible DC offset by 10uF 25V cap C3 and then pass thru opamp and again (?!) decoupled to kill DC offset by 10uF 25V cap C9.
 And before the poor Front Left channel even reach the aplifier, then there is yet another decoupling capacitor - again 10uF 25V C13.

 I cannot help thinking that these caps (mainly because they are NOT audio grade ones AND there is too much of them) will badly affect quality of the output.

 How about keeping only the C13 and using a 22uF 25V Elna RFS instead of known bad cap CapXon?

 Holly Grail would be no cap, of course. But then I need to worry about DC offset, I suposse.


*AudioCats* -  Quote:


 prefer AD8599 over LM4562? 
 

Well, you did extensive work there, thanks a lot. The way I look at the results it mean that the LM4562 is still a good choice for me, because they are fast-enough for the guitar music 
	

	
	
		
		

		
		
	


	



 (and electronic music/games)

 But you made me think, if the subwoofer opamp should not be better other that LM 4562 
	

	
	
		
		

		
		
	


	







 Did it can help, since the source of audio signal is my modified X-Fi with all four of the LM4562 opamps???


*majkel* -  Quote:


 Both OPA2134 and especially LM4562 are total sonic crap. 
 

I quess your ears are too good - or too spoiled by too good outputs. I did not yet hear anything like that, so... Please bear in mind, that the X-Fi Fatal1ty is nothing supergreat, even modified, and that I already modified the card to use the LM4562 opamps... 
	

	
	
		
		

		
		
	


	



http://www.head-fi.org/forums/f6/x-f...lution-216791/

 So do you think that it really can change anything, what opamps I use there?

 Check out the schematics. There is IMHO much more that kill the audio.

 Frankly spoken, as I see it, the whole schematics is one big failure - to be taken from a audiophile point of view.

 All I see is one opamps in X-Fi, then their signal lost on resistors and then yet another opamps and then the output amplifiers.

 Now the best way would probably be to get rid of the second opamps at all and drive the output aplifiers directly from the X-Fi opamps.
 Of course with the potentiometer to regulate the volume, but that it is. Nothing else.

 That would require top-to-bottom rework of the speakers, tough.

 But if I keep the X-Fi opamps not too much overloaded, then I probably can get the highest quality possible this way - eg. the best opamp is not two good opamps in line, but only one 
	

	
	
		
		

		
		
	


	







 What do you think?

  Quote:


 AD8599 is a great and safe idea. 
 

What if I'm a big fan of electronic music, old demos and guitars? 
	

	
	
		
		

		
		
	


	



 AudioCats mentioned in his testings ( http://www.head-fi.org/forums/f6/sta...9/#post3536731 ) that a "not as sharp as I want for playing Rock/electric guitar though" ...

 What about use it just for the subwoofer opamp?


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## AudioCats

the 8599 is warm and juicy, for sure. In the baby stax amp the sound is also altered by the output stage, so it is hard to say if the 8599 won't work great for electronics and guitar stuff in your system. I'd say install a DIP socket and try them both and see which one you like more.


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## AudioCats

also, when I was doing the test, the output capacitors were not audio grade boutique caps. With sharp/cold sounding boutique caps (such as Kimber) for output, the 8599 can sound quite nice for electronics music.... in the 001 amp that is.


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## trodas

Thanks a lot, AudioCats, for your explainations. Looks like the AD8599 might be very well worth the try - if for nothing else, then for the subwoofer opamp.
 From what I read it sounds that the bass line is great with this one, right? Better with more details that from LM4562, right?

  Quote:


 it is hard to say if the 8599 won't work great for electronics and guitar stuff in your system. I'd say install a DIP socket and try them both and see which one you like more 
 

You are right. But this thing will be in the subwoofer case, so the vibrations migh have lethal impact on any sockets... so it will be just for testing.

 But you avoided the main question - or I put it very wrong, as my vocabulary is limited and english is not my main language anyway 
	

	
	
		
		

		
			





 The main question is - *could any opamp in my amp do any reasonable difference when in the X-Fi that act as source of the audio incomming utilizing the 4 pieces of LM4562?*
 I mean - when the previous opamps is LM4562 - could opamps AFTER them matter noticably? I must say that I'm a bit skeptical about it... if something is broken (eg. the signal is not as good, as it can be from the X-Fi itself - as majkel put it so straightforward - "both OPA2134 and especially LM4562 are total sonic crap" ) already, then any attempt of fixing it could have only minimal impact...

 So in the end, the most easy replacement - a 4pcs of the LM4562 - could be still a reasonable solution.

 Still it should sound better that with the current NJM4558 ... right?


*majkel* - hmmm, I was under the impression that the LM4562 is a very good opamp? At least from reading the http://www.head-fi.org/forums/f46/ho...no-56k-226975/ X-Fi mod guide. Do I got it wrong and should I consider replacing the X-Fi opamps once again? 
	

	
	
		
		

		
		
	


	




 And the AD8599 seems to be produced only in the SOIC package - witch is idea for X-Fi, but far less ideal the the SW-5.1 HT, as it utilize DIP opamps. Four of them.


*AudioCats* -  Quote:


 when I was doing the test, the output capacitors were not audio grade boutique caps. With sharp/cold sounding boutique caps (such as Kimber) for output, the 8599 can sound quite nice for electronics music 
 

Interesting idea. I do have to admit that I considering large amount of capacitor removal/exchange/upgrade with the amplifier. I got plenty of experience with soldering and modificating stuff, however mostly only computers ... so I did not modify amplifier before. I made some as student, but these times are long behind...
 And I do have so many questions about modification of the circuits. Should I start another thread - eg. How to modify the Genius SW-5.1 HT audio circuit, or we can deal with it there? 
	

	
	
		
		

		
		
	


	



 I wonder if anyone can critically look at the proposed modifications by me. nd of course, since I'm a bit audio n00b, then suggest a nice decoupling caps as well - if even need.
 I still believe that I should remove as many decoupling caps, as possible. In the L, R, RL, RR and CENTER channels are utilized 3 decoupling caps per channel (What!!!) and in the SW channel - well - there is 5 decoupling caps along the line! 
	

	
	
		
		

		
		
	


	










 This is NUTS, in my opinion. But I could be wrong, of couse... that is why I asking, so, thanks for your opinions


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## Doru2010

Dear Trodas,
   
  I appreciate your effort to make sound better the SW-5.1 HT
   
  I own one of this model and I am interested to adapt a digital (coaxial or optical) input module in order to make a digital link between the computer' soundcard and the Genius Speakers.
   
  What do you think about that?
   
  I think this upgrade will revive these speakers
   
  Kind regards,
   
  D


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