The Opamp thread

[imran27]

Yesterday again, tried my XD-05 with Stealth Sonics U9 and U4 IEMs

Every opamp in my collection was noisy and unjustified to drive them. Only OPA1692 did justice that it was very silent, had an amazing attack and decay.

OPA2209 is the noisiest but also the most transparent and detailed. If only the hissing could be tamed I am sure OPA2209 can smoke every other opamp.

 

[toear]

Yesterday again, tried my XD-05 with Stealth Sonics U9 and U4 IEMs

Every opamp in my collection was noisy and unjustified to drive them. Only OPA1692 did justice that it was very silent, had an amazing attack and decay.

OPA2209 is the noisiest but also the most transparent and detailed. If only the hissing could be tamed I am sure OPA2209 can smoke every other opamp.

For the OPA1692 did you solder it yourself? And if so, where/what kind of adapter did you get/use?

I managed to find a pcb that matches a Us8 package to dip8, and my understanding is that vssop8 is the same as us8?

Or could you recommend a supplier that sells the opa1692 mounted?

Thank you

 

[imran27]

For the OPA1692 did you solder it yourself? And if so, where/what kind of adapter did you get/use?

I managed to find a pcb that matches a Us8 package to dip8, and my understanding is that vssop8 is the same as us8?

Or could you recommend a supplier that sells the opa1692 mounted?

Thank you

https://www.aliexpress.com/item/20p...SMD-to-DIP-0-65-1-27mm-pitch/32774064574.html

Can't guarantee quality though.

Seems to have good reviews

 

[toear]

https://www.aliexpress.com/item/20p...SMD-to-DIP-0-65-1-27mm-pitch/32774064574.html

Can't guarantee quality though.

Seems to have good reviews

bingo! Thank you!!

 

[Rroff]

Yesterday again, tried my XD-05 with Stealth Sonics U9 and U4 IEMs

Every opamp in my collection was noisy and unjustified to drive them. Only OPA1692 did justice that it was very silent, had an amazing attack and decay.

OPA2209 is the noisiest but also the most transparent and detailed. If only the hissing could be tamed I am sure OPA2209 can smoke every other opamp.

I've not noticed any background noise to speak of with the amp I posted with the OPA2209s - I've a bunch of Sennheisers including Momentums (which don't need amping but reveal noise due to sensitivity), various IEM models, HD600 and HD650 and some varied Beyerdynamics and a pair of Sony MDR. The only opamps really I notice any noise with that kind of design are the LM4562 and LME4xxxx series which seem a touch more susceptible to stray EMI/RF than most, unless you take additional steps to shield them, for some reason.

 

[imran27]

I've not noticed any background noise to speak of with the amp I posted with the OPA2209s - I've a bunch of Sennheisers including Momentums (which don't need amping but reveal noise due to sensitivity), various IEM models, HD600 and HD650 and some varied Beyerdynamics and a pair of Sony MDR. The only opamps really I notice any noise with that kind of design are the LM4562 and LME4xxxx series which seem a touch more susceptible to stray EMI/RF than most, unless you take additional steps to shield them, for some reason.

In XD-05 OPA2209 is quite noisy.

About LME, yeah they are susceptible. I hear interference as soon as I open whatsapp of facebook on my phone near my XD-05 while using LME49720 or LM4562

I suspected it could be the PSU noise (XD-05 uses boost converters to get +/-9 VDC, but then OPA2209 has a better PSRR than OPA1692.

The only place where OPA2209 looks worse is the Open Loop Gain, CMRR and Slew Rate.

 

[nesty]

I ordered 2 of those Opa1611 modules. Very nice opamp anyway but I am captivated by these modules. For the price these are a steal... Oh and the underside has LED's. Bonus!

@SpudHarris , what is your test unit where you place those opamps? thanks

 

[SpudHarris]

@SpudHarris , what is your test unit where you place those opamps? thanks

Nesty, it's the Burson 'Lycan' it's just an honest testbench. Not flashy nor overly expensive but a great amp for rollers...

 

[Rroff]

Nesty, it's the Burson 'Lycan' it's just an honest testbench. Not flashy nor overly expensive but a great amp for rollers...

Always the best kind of test bench - I mainly use a glorified (better power supply) CMOY type circuit - but I've worn out some of the connections from plugging things in and out so need to rebuild it :s

 

[SpudHarris]

I'm sure the original power supply was good but I swapped it out for a Graham Slee PSU1 which I have always rated highly.

I forgot how much fun rolling was... The Opa1611 modules I bought are really quite amazing. Will drop some standard ones in tonight to compare

 

[nesty]

Nesty, it's the Burson 'Lycan' it's just an honest testbench. Not flashy nor overly expensive but a great amp for rollers...

@SpudHarris , that's great but sadly Burson already stopped the mass production of Lycan. You're lucky to have one.

 

[FritzS]

I'm sure the original power supply was good but I swapped it out for a Graham Slee PSU1 which I have always rated highly.

I forgot how much fun rolling was... The Opa1611 modules I bought are really quite amazing. Will drop some standard ones in tonight to compare

I own an Graham Slee Solo to, its older and one of the „green series“ - with switch PSU. I want to mod this amp.
Currently it have 33 Ohm in series to the output. This is to high for some low impedance headphones, so as AKG K812.

 

[raoultrifan]

Hi FritzS,

If it's about this schematic found on AliExpress https://ae01.alicdn.com/kf/HTB1d9Fh...r-f-rence-Grammy-Graham-Slee-SOLO-Hifi-fi.jpg then I'd say to leave it as it is, mostly because the BC550/560 were not meant to drive low impedance sources. The amp itself is probably very low noise and of good quality to drive high impedance cans instead, so I would keep it for this purpose mainly.

If still want to dive deeper into this, then you cold try adding an output buffer like Lehman here: https://cdn.head-fi.org/a/6666954.jpg. Without having a powerful output buffer I can't recommend you to lower the existing output resistors.

P.S.: Having an output buffer in place could make the output resistors to disappear or at least to notched them down near to few ohms only, as per https://www.head-fi.org/threads/asu...-dac-cebit-2011.542563/page-235#post-14145076.

 

[raoultrifan]

On a 2nd thought, paralleling BC550/560 (like you've done it here: http://www.blue-danube.at/hifi/wna.php#Modification1) could do the job and let you lower the output resistance after all, but don' remove the output cap because the DC could be higher.
https://www.edn.com/Pdf/ViewPdf?contentItemId=4434614

Good luck and please let us know of the results! If you have access to a scope then please share initial and final results when sine and square waves are applied.

 

[FritzS]

@raoultrifan
thank you for this hints.

You bring me an idea.
Another way would be to replace the two end-stage transistors with BUF634.
I have some of them in stock.

AKG K812 don't like the 33 Ohm in series to the output. My model use 33 Ohm resistors instead 120 Ohm here
https://ae01.alicdn.com/kf/HTB1d9Fh...r-f-rence-Grammy-Graham-Slee-SOLO-Hifi-fi.jpg