[AOARoses]

Has anyone tried putting 2 x LME49990 on HPA-3U+ ? I saw previous post about 2 x LME49710, and the result was better high end. Just wondering if it works with 2 x LME49990? I've no knowledge of swapping op amps, hope it does not destroy anything if I ask my friend to put LME49990 on.

 

[raoultrifan]

Also, please ask your friend to check for oscillations or strange harmonics with a decent scope, just to be sure LME49990 will not oscillate.
 
Waiting for your findings about the sound quality with these opamps.

 

[AOARoses]

  Also, please ask your friend to check for oscillations or strange harmonics with a decent scope, just to be sure LME49990 will not oscillate.
 
Waiting for your findings about the sound quality with these opamps.

Thanks for the suggestion 

  Will I be able to distinguish by ear if there are strange harmonics?

 

[jeff7742]

I want to get the HPA-3B. I will eventually get a balanced DAC, but for now I only have a single-end DAC. Will I still hear some improvement over a single-ended amp (using balanced headphones)? I have noticed that some balanced amps have something called a "phase splitter" that simulates balanced for RCA inputs. Does the HPA-3B have anything like that? -Thanks

 

[raoultrifan]

Hi, 
 
HPA-3B is fully balanced inside, but it also has a single-ended output. I strongly recommend you to use the balanced XLR output for best results.
 
On the RCA plugs you can only attach single-ended DAC source.
 
P.S.: In case you don't want to balance your headphone, then aim to active ground headamps like the ones made by Meier Corda or perhaps the TEAC UD-503.

 

[jeff7742]

  Hi, 
 
HPA-3B is fully balanced inside, but it also has a single-ended output. I strongly recommend you to use the balanced XLR output for best results.
 
On the RCA plugs you can only attach single-ended DAC source.
 
P.S.: In case you don't want to balance your headphone, then aim to active ground headamps like the ones made by Meier Corda or perhaps the TEAC UD-503.

 
Thanks. I was comparing this amp to the cheaper Aune X7S. The Aune had balanced outputs, but only single-ended inputs. They use some kind of phase-splitter technology which somehow simulates a balanced input (like the Liquid Carbon). I was just wondering if the HPA-3B did the same thing with single-ended inputs.

 

[raoultrifan]

I believe Cavalli did an additional circuit after the RCA inputs that are inverting the phase for both L and R inputs and attack the internal amplifier with native balanced signal: + & - for each of the R and L inputs. I don't see such circuit inside the HPA-3B and don't see its point anyway, as long as XLR cables helps a lot in transmitting analog signal between source (DAC) and preamplifier or amplifier.
 
If you;re thinking in upgrading to balanced and if you can purchase a Liquid Carbon then go for it, because its a great amplifier, but if not, then just forget about the RCA and jack plugs and only use the XLR ones. How analog signal is transmitting between RCA plugs and internal acitve circuit should not concern us too much; let's use balanced XLR if possible.

 

[jeff7742]

Oh yes, I definitely want to use XLR. But I need some time to shop around for a balanced DAC. I was just wondering if, in the mean time, I would notice any improvement with my single-ended DAC.

 

[AOARoses]

  Also, please ask your friend to check for oscillations or strange harmonics with a decent scope, just to be sure LME49990 will not oscillate.
 
Waiting for your findings about the sound quality with these opamps.

My engineer friend put the double LME49990 in my HPA-U3+, and I heard more energy coming out of my TH-X00 purpleheart. It is also cleaner at higher volumes (I guess the new chip has less distortion???). The difference is very minimal but definitely better than the stock.

 

[raoultrifan]

LME49990 is a great opamp, I'm sure it may sound better than the original from HPA-U3+, just double check for oscillation.

 

[raoultrifan]

Well, you can use the single-ended RCA inputs as well and use balanced headphones, I'm pretty sure the soundstage will increase Usually, ugrading default single ended cable to a custom balanced one is considered an improvement.

 

[canthearyou]

I want to get the HPA-3B. I will eventually get a balanced DAC, but for now I only have a single-end DAC. Will I still hear some improvement over a single-ended amp (using balanced headphones)? I have noticed that some balanced amps have something called a "phase splitter" that simulates balanced for RCA inputs. Does the HPA-3B have anything like that? -Thanks

Be sure to check the classifieds for a great deal. Wink wink.

 

[jeff7742]

Just picked up an HPA-3B. It's 12% off for black friday. Look forward to hearing it! Some great reviews on it.

 

[loserica]

  Just picked up an HPA-3B. It's 12% off for black friday. Look forward to hearing it! Some great reviews on it.

I bought HPA-3U a few days ago from Spain. 360 Euros (20% off) and free shipping in the UE.

 

[jeff7742]

Got my HPA-3B today. I can only listen single-ended since my headphone cable isn't balanced yet. After a few hours burn-in my first impressions are that the sound is quite refined - more so than my SMSL VA2, and also much warmer than I thought it would be - almost lush. Maybe even too warm. I used to have to EQ my Beyer T1's since they were a tad bright. But no EQ with this amp. Soundstage also seems bigger. Overall I'm pleased though. Can't wait to finish my balanced cable and listen balanced.