[SpudHarris]

Hmmm, not a massive amount of difference to my ears. Both are amazing OpAmps but with the OBCA mod on the 5534 I am favouring them slightly more than the Muses01 (my favourite of the Muses). I am astounded that after so many years rolling and tweaking that I have only just stumbled over this.

I tried the AD744 OBCA a while ago (which was great) but for some reason never tried the 5534 with the same pinout. The Muses01 is an amazing OpAmp and I think it has a very slight advantage over the 5534 for male vocals but this is a personal preference as I prefer them slightly more forward in presentation but generally I am finding the 5534 more musical which suits my HD800's to a tee....

If you take into account the price of the 5534 it's an absolute "golden nugget" not to be missed. Remember though, the OBCA mod is the magical mod that turns this "sows ear into a silk purse"

Man, don't you hate cliches.... I try to avoid them like the plague

 

[pelopidas]

Looking at the pictures of your 5534 you both have different mods with the resistors

The 7.7k is Class A biasing if i understand correctly.
Spud, can you explain how your mod works? It looks like you are bypassing the output and turning the comp + (+V) into an output.
I am trying to wrap my mind around what is going on here but I dont get it

. Please explain and help me.
 
I also ordered some NE5534AN to test out here, but I am unsure of what is happening with the OBCA. Also, it is probably just the picture, but are the ends of the resistor touching between pin 6 and 7?

 

[SpudHarris]

I think our mods are the same but you can't see the detail on theory_87's.... I made adapters so I could use with both 744 and 5534 but completely forgot about the 5534 and never actually got around to buying any until recently.

OBCA is Output Bypassed Class A so you are correct. I'm no expert, I just carry out recommended mods. The pins of 6 and 7 do not touch.

 

[pelopidas]

I was reading some others who had done this mod and were generally pleased with it
 
http://www.head-fi.org/t/133784/opa627-v-sa5534an-obca-impressions-sm3
 
They did note that there was some reduction in detail. Have you noticed this? How big of an effect is there?
As you can tell, these are questions from someone who is impatiently waiting for his own 5534s to arrive.

 

[theory_87]

Nope. Infact i find everything improve slightly compare to unmodified ne5534an. Not day and night on my humble iem but nevertheless still noticeable.

 

[Lohb]

Is there anything like the ADA4637-1BRZ that will work with an altoid amp ?
Friend found LME4562 too brittle in the long-run.

 

[pelopidas]

Hi Lohb,
 
there are a few parts to this answer.
 
What impedance headphone is your friend using? The LME 4562 is rated to drive 600 ohm and can do 26 mw per channel. (high voltage, low current)
this will not be ideal for for earbuds or anything in the low ohm range ( they go down as far as 16 ohms) (high current required to drive, voltage less so)
The quickest and simplest fix would be to put a JRC 4556 in there. It can drive 150 ohm and can do 70 mw. This is a much more robust opamp for a cmoy.
 
However, from my experiences with cmoys, the rise in distortion, from using a lower impedance headphone than is ideal, does not really contribute to a brittle sound. That is usually a result of the wrong type of capacitor. I don't know what variation of cmoy in a tin you have, but you either have a resistor based voltage divider or an IC based one. With the resistor voltage divider, you will have 2 electrolytic capacitors of the same value on the board. With an IC based one, you might only have one capacitor. If you "cheap out" on these you will have all kinds of maladies. Put in Jamicons and it will sound like your ears are full of cotton, just absolutely dead. Put in Panasonic FC and it will have a fatiguing top end that will make your ears bleed. Brittle, sybillant but otherwise dynamic. The safest bet is Elna Silmic II. Great bass and sweet, detailed top end.
 
If your friend wants to leave the board as is, get a 10uf Silmic II and solder it directly onto the LME 4562 + -  This will revolutionize your LME4562. You could also use the SEPF 22uf which is even smaller and sounds just about as good.  Other capacitors do not have this magic. I have tried ceramics, all types of film all the way up to huge 22uf film capacitors. So try either the Silmic or the SEPF.

 

[Lohb]

  Hi Lohb,
 
there are a few parts to this answer.
 
What impedance headphone is your friend using? The LME 4562 is rated to drive 600 ohm and can do 26 mw per channel. (high voltage, low current)
this will not be ideal for for earbuds or anything in the low ohm range ( they go down as far as 16 ohms) (high current required to drive, voltage less so)
The quickest and simplest fix would be to put a JRC 4556 in there. It can drive 150 ohm and can do 70 mw. This is a much more robust opamp for a cmoy.
 

Hi there he will be using 16-32 ohm earphones and headphones.
I think JRC 4556 in there will be easiest for him.

 

[pelopidas]

Is he using a single 9v battery or two 9v batteries? 18v sounds a lot better.
Also, if the sound continues to be harsh with the 4556 it is most likely bad capacitors.
The difference between opamps is much more subtle than the difference between capacitors.
Can you provide a picture of the amp so we can see the components?

 

[Lohb]

Is he using a single 9v battery or two 9v batteries? 18v sounds a lot better.
Also, if the sound continues to be harsh with the 4556 it is most likely bad capacitors.
The difference between opamps is much more subtle than the difference between capacitors.
Can you provide a picture of the amp so we can see the components?

He is using BioScioenceGeek Altoid which is regarded as one of the better ones. Yes, 18 volts.
4562 always Sounded kind of detailed/fast but icy/brittle.

 

[pelopidas]

Can you find out the make of the capacitor? It looks like a cheap one in the pics I found.

 

[burdie]

Guys, need to ask a question on LME49720ha metal can version.
Recently I soldered lme49720ha to 2 units of to9 to dip8 socket, and 2 units solder directly to dip-8 socket.
I am using Matrix HPA-3B headphone amp and I swap the stock lme49860 to 49720.
The problem I encounter is when I used the direct dip-8, my amp will auto off (protection) if I am using high gain (20db), low and mid gain have no problem at all.
The TO99 to dip-8 adaptor works on all gain setting. All opamp purchased at the same time from one single supplier.
will it be the socket problem or I am just unlucky to receive faulty opamp, or this is common problem on metal can?
Thanks

 

[pelopidas]

Perhaps its not making good enough contact? The metal can legs are a bit thinner than regular DIP socket legs. Perhaps sanding the legs to make sure they are super clean and make sure you have positive contact in the socket. Otherwise.... solder it to a dip socket and try it then?

 

[pelopidas]

Well, my Signetics NE5534AN arrived. I ordered 4, which was a good thing since one was a dud. It is noisy, even though music comes through.
I can't test it in my heaphone amp without rebuilding it since it produces 120mv of offset. Running the LME49990 in the headphone gives me 0.3mv offset.
So I am evaluating it in the buffer position of my DAC.
My first impression: Wow, this is much better than 30 year old tech has any right to be
Male vocals sound really good. It is a melodic opamp. The Bass is huge!
After some careful listening I noticed that the bass is wooly, not taught. So at this point I put a 22uf SEPF on the + - and this tightens up the bass. Now it is clean and tight but DAMN its a lot of bass.
It sounds like someone turned on the Bass boost on a cmoy.
So compared to the 49990 in the buffer position i would say that it is good if you want FAT BASS. It is fast enough for any musical genre but its not quite my taste. 
I listen with an HD650 and the bass overwhelms the music. At first it sucks you in but soon you get bass fatigue. It does not seem as airy either but that can be because of the overwhelming bass. 
 
Next up: Try it will a different capacitor. After that I will try the Output Bypass Mod.
 
Spud! can you recommend the correct resistor value for the mod? It looks like yours is 2.2k. Is there a reason for that value, or will anything in a certain range work?

 

[amit_talkin]

Guys, need some suggestions. What would be best suitable for bass lover? I am gonna replace 3 of stock op-amps on my xonar essence stx.
My M50x arriving in 2 days. I miss that "mega bass" feeling which sony had with their walkman series. especially with w800i.