The Opamp thread - Page 275

Because of possible poor contact?

Quote:

Originally Posted by SecrtAgentMan 

Great to hear ^^

 

So I've been reading through the thread and I still can't come to a conclusion as what to get.

 

I listen to some bass heavy music, and I'd like for soundstage and sound positioning to be present as well if possible since I do game with these headphones.

 

Currently I use the ATH-M50s. If anybody could give me a recommendation that would be great.

 

Thanks.

Unfortunately, unless someone is using the same source, same amp, and same headphones, not to mention having different ears and different tastes, it's really hard to make recommendations with any guarantee.  In my limited experience with rolling op-amps (compared to several other contributors, here), I'd say your best bet is to start rolling and see what sounds good to you.  It can get expensive, but you can start with the stuff that everyone else is raving about.  In my case, that would be the aforementioned HA5002 for buffers and the LME49990 for input voltage gain.  But that's just the "flavor of the week."  Hopefully, it will be the flavor of the month, or longer...

Which amp are you using?

Mike

Quote:

Originally Posted by zilch0md 

 

Unfortunately, unless someone is using the same source, same amp, and same headphones, not to mention having different ears and different tastes, it's really hard to make recommendations with any guarantee.  In my limited experience with rolling op-amps (compared to several other contributors, here), I'd say your best bet is to start rolling and see what sounds good to you.  It can get expensive, but you can start with the stuff that everyone else is raving about.  In my case, that would be the aforementioned HA5002 for buffers and the LME49990 for input voltage gain.  But that's just the "flavor of the week."  Hopefully, it will be the flavor of the month, or longer...

 

Which amp are you using?

 

Mike

Well I'm using a sound card so no amp (unless the sound card is considered one). It's the Asus Essence STX.

So 2x LME49990 for I/V and then just 1x HA5002 for buffer? Where can I buy the buffer? I saw the LME's on Ebay.

Quote:

Originally Posted by SecrtAgentMan 

Well I'm using a sound card so no amp (unless the sound card is considered one). It's the Asus Essence STX.

 

So 2x LME49990 for I/V and then just 1x HA5002 for buffer? Where can I buy the buffer? I saw the LME's on Ebay.

For the HA5002 buffer, already soldered to a DIP8 adapter, try sending a PM to Head-Fi member HiFlight.  Ask Ron if he would be willing to do it for you and how much it would cost, including shipping.

Ron solders the HA5002s routinely for his various TopKits (collections of popular op-amps he puts together for owners of iBasso headphone amps).

Warning:  The LME49990 is a JFET op-amp that requires a minimum operating supply voltage of +- 5V.  Most portable headphone amps can satisfy this requirement, but your sound card might not.   ???

UPDATE (two months later):  The 49880 is a JFET, but the 49990 is not (at least I can't find any reference saying that the 49990 is a JFET...)

Here is the datasheet for the LME49990:   http://www.ti.com/lit/ds/symlink/lme49990.pdf

Here is the datasheet for the HA5002:  http://www.intersil.com/content/dam/Intersil/documents/fn29/fn2921.pdf

Even if the sound card can satisfy the LME49990's power requirements, there's something else to consider:  The LME49990's THD and Noise specifications improve as the supply voltage increases.  In other words, you will get the best possible performance out of an LME49990 when the supply voltage is at +- 15V (just below its absolute maximum of +- 18V).   

If you are unable to determine the operating supply voltage delivered by your sound card, you might be better off selecting an op-amp that's designed for lower operating voltages. 

The OPA1611 would be a better choice if you don't know what your sound card's supply voltage is, as the bi-polar OPA1611 can use an operating supply voltage as low as +- 2.25V up to +- 18V.  It's a very popular op-amp, too - known for being extremely transparent and neutral.  (It's the op-amp used in the Meier Audio Stepdance portable amplifier, for example.)  But even the OPA1611 sounds best when supplied with 15 Volts.

Here is the datasheet for the OPA1611:  http://www.ti.com/lit/ds/symlink/opa1611.pdf

Ron (HiFlight) would also be able to quote a price on the OPA1611s, already soldered to DIP8 adapters.

With the understanding that you are proceeding at your own risk, you can always just order them, roll them in, and see what happens.   

Mike

Quote:

Originally Posted by zilch0md 

 

For the HA5002 buffer, already soldered to a DIP8 adapter, try sending a PM to Head-Fi member HiFlight.  Ask Ron if he would be willing to do it for you and how much it would cost, including shipping.

 

Ron solders the HA5002s routinely for his various TopKits (collections of popular op-amps he puts together for owners of iBasso headphone amps).

 

Warning:  The LME49990 is a JFET op-amp that requires a minimum operating supply voltage of +- 5V.  Most portable headphone amps can satisfy this requirement, but your sound card might not.   ???

 

Here is the datasheet for the LME49990:   http://www.ti.com/lit/ds/symlink/lme49990.pdf

 

Here is the datasheet for the HA5002:  http://www.intersil.com/content/dam/Intersil/documents/fn29/fn2921.pdf

 

Even if the sound card can satisfy the LME49990's power requirements, there's something else to consider:  The LME49990's THD and Noise specifications improve as the supply voltage increases.  In other words, you will get the best possible performance out of an LME49990 when the supply voltage is at +- 15V (just below its absolute maximum of +- 18V).   

 

If you are unable to determine the operating supply voltage delivered by your sound card, you might be better off selecting an op-amp that's designed for lower operating voltages. 

 

The OPA1611 would be a better choice if you don't know what your sound card's supply voltage is, as the bi-polar OPA1611 can use an operating supply voltage as low as +- 2.25V up to +- 18V.  It's a very popular op-amp, too - known for being extremely transparent and neutral.  (It's the op-amp used in the Meier Audio Stepdance portable amplifier, for example.)  But even the OPA1611 sounds best when supplied with 15 Volts.

 

Here is the datasheet for the OPA1611:  http://www.ti.com/lit/ds/symlink/opa1611.pdf

 

Ron (HiFlight) would also be able to quote a price on the OPA1611s, already soldered to DIP8 adapters.

 

With the understanding that you are proceeding at your own risk, you can always just order them, roll them in, and see what happens.   

 

Mike

Mike,

you my friend have come a long way in a short time

I know we joke about the addiction sometimes but you really have started to understand the science behind OpAmps. More power to you. I'm still learning slowly, I recon I have more experience in terms of physical try outs but by probably less understanding than you haha. You sound like a pro mate!

We are agreed on the 49990 though. I wish someone would make a decent powered portable optimised for that chip. I'm not aware of one but maybe anyone in the know could chime in if there is such a thing....

Ta! - Nigel

The analogue stage for the STX is +/-12V, so looks like no go on the 49990.

Which is within 49990's range (+/-5V to +/-18V) as far as voltage.

Thanks guys, also I've been looking on Ebay for the LME49990 soldered to a DIP8 adapter.

I've noticed there are two of them, one that comes in a pair, and one that is just as single one with 2 LME49990's soldered to both sides of the adapter.

Is one better than the other? I've been looking at frugalphile's listing.

49990 is a single, or mono, opamp, so you need two on one adapter to replace a dual opamp like OPA2134 or OPA2604.

Quote:

Originally Posted by SecrtAgentMan 

Thanks guys, also I've been looking on Ebay for the LME49990 soldered to a DIP8 adapter.

 

I've noticed there are two of them, one that comes in a pair, and one that is just as single one with 2 LME49990's soldered to both sides of the adapter.

 

Is one better than the other? I've been looking at frugalphile's listing.

Chances are the DIP-8 slot your plugging op-amps into is dual channel and the LME49990 (SOIC) is single channel op-amp.

So two LME49990 SOIC op-amps need to be soldered on to a dual SOIC to DIP-8 adapter.

I use the Essence STX if that is any help ^^

Quote:

Originally Posted by SecrtAgentMan 

I use the Essence STX if that is any help ^^

The Essence STX (& ST) comes with three dual channel DIP-8 sockets.

I'm using 3 AD797BRs in mine

The LME49990 seems to be well liked.

Thanks for the kind words, Nigel!   I'm always hoping somebody will swoop down and correct anything I write that's incorrect.  That's the beauty of forums like this - everything must pass peer review.  

There's so much collaboration going on here, at the moment - I dig this team work!

So, SecrtAgentMan...  It sounds like you can use these LME49990 duals, for example:

http://www.ebay.com/itm/DUAL-SOIC-LME49990-DIP8-ADAPTER-/190682726763?pt=US_Amplifier_Parts_Components&hash=item2c6593816b

Ebay seller Frugalphile's soldering is very neat and clean - I bought four singles from him for my PB2 amp. 

Go for it!  

Mike

Quote:

Originally Posted by Mad Max 

Which is within 49990's range (+/-5V to +/-18V) as far as voltage.

ahh yes, i misread the other post as max +/-5 no minimum 

Quote:

Originally Posted by PurpleAngel 

The Essence STX (& ST) comes with three dual channel DIP-8 sockets.

I'm using 3 AD797BRs in mine

The LME49990 seems to be well liked.

Its probably my fault are you using the AD797, it just sounds so good, but don't be surprised when they break from all the oscillation. :p

I have said before for my STX the following are on my list:

• LME49990
• OPA1612
• HA5002
• AD8599