[povidlo]

Burr Brown OPA2137P works with this amp. Thankfully it works with single and dual power supply. No ability to A/B, so all I can say is that it works and there is no hiss or static of any kind.

VE Megatron LO to HA-S
HD700 / DT1990 Pro are the headphones used

Thanks for sharing. So OPA2137P can act as both single and dual op amp, am i understanding correctly?

 

[povidlo]

I've been stacking Korg with ZiShan DSDs AK4499 Pro. They're of similar size. DAC is very good quality and Korg does a great job of reproducing the scene while adding pleasant harmonics to the mix. DSDs has variable line-out which complements Korg well because it helps to overcome the lack of gain on the amp. Otherwise there's little-to-no play room on the volume pot for most iem, buds and easy headphones. This stack produces authoritative sound with 1more triples.

 

[captblaze]

Thanks for sharing. So OPA2137P can act as both single and dual op amp, am i understanding correctly?

that pertains to the voltage. single (+ or -) or dual (+ & -) voltage. the HA-S is a single voltage design. Some Op amps run on both so that is why the BB works on the HA-S.

A single Op Amp is mono. Dual OP Amp / stereo. Quad Op Amp / 4 channels

 

[captblaze]

Now that i have had some time with 3 Op amps (2 included and a BB) some loose impressions. They all are good sounding Op Amps, but each has a strength the others don't. The NJHM 4580 seems to deal with 150 ohm transducers the best of all 3. The Muses01 does its best @ 150 ohm and above to 300 (don't have anything with higher impedance rating). The BB does its best under 150 ohm.

All in all, I am enamored with this Amp, and it has been used (and enjoyed) more than my other HP desktop HP amps during this time and into the immediate future.

*Bonus* - I found some pretty reliable 1.5v rechargeable batteries that give as much listening time as Energizer ultimate lithium batteries. Link ----> Amazon US

 

[povidlo]

I noticed there's a significant power output drop when Negative Feedback is enabled. It is mentioned in the manual but I haven't noticed it being so pronounced until now. The good part is that it makes Ha-S much more usable with non-hard iems and headphones in terms of volume knob room. I wonder if high output impedance might be somehow reduced with NF as well.

It's a good amp and is sensitive to source input quality. I picked up tunai ldac dongle to pair with HA-S and a small powerbank. The resulting output was coarse and hot. I'll be returning tunai. However with proper line input, such as from hm1000, output is clean and crisp. Hm1000 + HA-S = awesome r2r tube ldac stack.

Listening to th900ii, this stack takes the edge off the treble and plumps the mids up with bubbly harmonics. Still totl bass, well controlled and texturized.

 

[Thomastb]

Hi, I got a korg amp, using muses01, all BA IEM, but the tube sound is not that significant. Anything I can do to make it warmer?

Perhaps Op amp switching? Which Op amp makes the best tube sound? Does Burson vivid or classic work on this amp and any good effect?

 

[povidlo]

Hi, I got a korg amp, using muses01, all BA IEM, but the tube sound is not that significant. Anything I can do to make it warmer?

Perhaps Op amp switching? Which Op amp makes the best tube sound? Does Burson vivid or classic work on this amp and any good effect?

Welcome to the club.

What BA iem are you using? Although i understand the idea of pushing BA drivers through a warm source, Korg HA-S might not be the best option. HA-S has high output impedance, of 10 ohm i think, which could really mess up tonality of a BA iem which are typically sensitive and have low resistance.

Another factor is whether NFB is set to off or on. By default, it's off. With NFB on, there should be less harmonics and warmth present, but a more accurate presentation.

This Korg amp sounds analog and tubey with muses01 opamp. I don't think the opamp is the issue in your case.

 

[povidlo]

Now that i have had some time with 3 Op amps (2 included and a BB) some loose impressions. They all are good sounding Op Amps, but each has a strength the others don't. The NJHM 4580 seems to deal with 150 ohm transducers the best of all 3. The Muses01 does its best @ 150 ohm and above to 300 (don't have anything with higher impedance rating). The BB does its best under 150 ohm.

All in all, I am enamored with this Amp, and it has been used (and enjoyed) more than my other HP desktop HP amps during this time and into the immediate future.

*Bonus* - I found some pretty reliable 1.5v rechargeable batteries that give as much listening time as Energizer ultimate lithium batteries. Link ----> Amazon US

After doing a bit more research, I figured out that both stock opamps come in dual channel config only- meaning that dual channel bursons and most other popular opamps are indeed compatible with HA-S. V6 Classic and Vivids do fit with the little extension legs they come with- however the case cannot be closed due to V6's height. I only briefly tried Classic and the sound was a little off. V6s might be too demanding for Korg, but ymmv. I currently have Burson v5i inside. It's more dynamic and less laid-back than muses01. v5i is more bass and treble focused, while 01 is mid-forward.

 

[Thomastb]

After doing a bit more research, I figured out that both stock opamps come in dual channel config only- meaning that dual channel bursons and most other popular opamps are indeed compatible with HA-S. V6 Classic and Vivids do fit with the little extension legs they come with- however the case cannot be closed due to V6's height. I only briefly tried Classic and the sound was a little off. V6s might be too demanding for Korg, but ymmv. I currently have Burson v5i inside. It's more dynamic and less laid-back than muses01. v5i is more bass and treble focused, while 01 is mid-forward.

Which one has the most tube sound? Out of all Op amp u tried.

I believe both single and dual channel should be compatible for korg HA-S. Please correct me if I'm wrong

 

[povidlo]

Which one has the most tube sound? Out of all Op amp u tried.

I believe both single and dual channel should be compatible for korg HA-S. Please correct me if I'm wrong

i think on korg ha-s the tube effect is prominent regardless of op amp. with burson v5i/v6 vivid the sound presentation is more forward and energetic; with muses01/v6 classic, presentation is more relaxed and less dynamic.

can only confirm that dual channel op amps work fine; not sure about single channel ones but i doubt they'd work. i think when op amp is single channel, at least two of them would be required to provide stereo signal. while ha-s only has one op amp slot.

have you tried ha-s with a single dynamic or planar driver iem/headphone yet? due to high output impedance of 10 ohm, ha-s is likely to seriously mess up a frequency response of a multi-driver iem.

 

[Thomastb]

I think muses01 is single and njm4580 is dual. Please correct me if I'm wrong.
Yes planning to buy a single DD

 

[Thomastb]

Is burson significant upgrade to muses01? Thanks

 

[povidlo]

I think muses01 is single and njm4580 is dual. Please correct me if I'm wrong.
Yes planning to buy a single DD

mouser says muses01 is a Dual Operational Amplifier. knowledgeable folks in the opamp thread should be able to confirm.

Is burson significant upgrade to muses01? Thanks

i'm not permanently using neither v6 classic or vivid since case cannot be closed. only tested them briefly. between v5i and muses01, they're fairly on the level. v5i is more of a sidegrade with different tonality.
i would like to try sparkos and muses02 next.

 

[Thomastb]

Waiting your impressions on the new Op amp

 

[povidlo]

ha-s works well with cayin ru7 1bit dongle which has lo mode. case attaches magnetically to ha-s' aluminum casing, no straps needed.