[raoultrifan]

LME49600 from inside E1 is powered from +/-12V power supply, so it won't output more than 7.3V RMS per channel (I was able to measure almost 7.1V RMS actually, with 2V RMS input 1KHz sinewave). However, per it's datasheet: "the LME49600 is able to drive 32Ω headphones to a dissipation of greater than 500mW at 0.00003% THD+N while operating on ±15V power supply voltages".

Of course, for short-term peak you might be able to get spikes up to 1W of power per channel, but honestly...I can't keep on my head any of my hard to drive panars like Hifiman HE-560 and Fostex T50RP-mk3 with volume above 2 o'clock, unless the songs are recorded somewhere around -3dBFS. With 0dBFS my ears start bleading if volume is maxed out.

 

[Hopup]

Have anyone here tried TL072 op-amps on the amp? I have been using them for the buffer and it has very natural sound and pleasing sound (especially vocals) with my lower quality phones. Others slots I use muses.

 

[raoultrifan]

@Hopup, the older TL072 under no circumstances will have a lower THD+N than NE5532P, so unless you have a way to measure THD+N, I strongly recommend you to leave your default NE5532P opamps untouched in there.

See https://www.head-fi.org/threads/bur...sion-and-reviews.854912/page-18#post-14799047.

All I can say is that with default NE5532P mounted in I/V stage I get much less distortions that with MUSES01: 2nd harmonic is about 16-18 dB lower with NE5532P vs. MUSES01 and 3rd harmonic is about 2-3 dB lower as well.

MUSES01 in I/V, THD+N: 0.0067%

NE5532P in I/V, THD+N: 0.0024%​

 

[seateam]

QUOTE FROM RAOULTRIFAN

I really liked it, but OPA2604 were very hot to touch and when I measured E1's power consumption I realized that each OPAMP is getting an additional power of almost 1W/each (over 15W with OPA2604 vs. almost 12W with NE5532)! Scope did proved that OPA2604 is oscillating in E1's I/V stage, so I removed them for good. Same might apply to LT1028, LME49990 and AD797, even if the sound is very good to your ears: http://www.head-fi.org/t/542563/asus-essence-one-headphone-amp-dac-cebit-2011/795#post_8275193 or http://rockgrotto.proboards.com/thread/7599/assus-xonar-essence-dac?page=2 etc.

I have been meaning to reply to this a long time ago. So because I found opa2604 sound so amazing I continued using them when I made a very interesting discovery.
When used on rca output x 2 opamps became very hot. When I started using balanced line out to my amplifier all four X 4 OPA 2604 opamps cooled down to normal temp. I put heatsinks on for just in case but not needed if running balanced out which uses all 4 opamps and full circuit of both dac chips. They run normal temp ,so I think no oscillation IMHO, when used as above for balanced out.Maybe something in the circuit changes for balanced mode which stops oscillation ??? I have used my DAC like this since 2014 (5 years) with no problems . I have large floorstanding speakers with high sensitivety through preamp and mono blocks so can hear small changes imediately. My friend has muses edition , and for me and him OPA 2604 sounds better in I/V. I have a feeling that when Asus designed this DAC , they put all their focus on Balanced line output and the single (RCA) output is a compromise.
Even with STD Opamps, sound from balanced sounds much better than RCA output. Much more detail,lower noise floor,cleaner treble,stronger bass and more dynamics. Unfortunately I do not have a scope to confirm all , but would love your input on it Raoultrifan.
Greetings

 

[raoultrifan]

I do like the E1 too, even it's kinda old at this moment. In single-ended I'm using the internal amplifier for headphones, but on the RCA plugs I have Mackie monitors connected.
The XLR balanced plugs are used in conjunction with Matrix HPA-3B, this way I can listen fully balanced from "head to tail".

To minimize distortions I can only recommend in I/V LME49720 or 5532 opamps. For LPF the same opamps could be used as well.

What exactly would you like me to measure, please? Although, I'm not sure I have the time for this in the next couple of months, but still worth asking.

 

[seateam]

I do like the E1 too, even it's kinda old at this moment. In single-ended I'm using the internal amplifier for headphones, but on the RCA plugs I have Mackie monitors connected.
The XLR balanced plugs are used in conjunction with Matrix HPA-3B, this way I can listen fully balanced from "head to tail".

To minimize distortions I can only recommend in I/V LME49720 or 5532 opamps. For LPF the same opamps could be used as well.

What exactly would you like me to measure, please? Although, I'm not sure I have the time for this in the next couple of months, but still worth asking.

Hello Raoultrifan
I thought if you ever had time to insert OPA 2604 back in I/V and make sure balanced out is connected, and then check for oscillation. As I said when running in balanced out the 2604 run cool. However when you run RCA out the opamps heat up in pairs 1 and 3 the 2 and 4. Years back you said you liked the sound of OPA 2604, so I thought it would be nice if you checked the balanced out way for oscillation and have a listen to their sound again , especially against muses 01. I use standard opamps in LP

 

[raoultrifan]

Hello,

OPA2604 was oscillating in both I/V and LPF stages, even if there was no plugs connected in RCA and XLR. It's more related to the PCB of the E1 and the power supply and grounding.
For safety and best measurements I can strongly recommend LME49720 and/or LM4562 and/or NE5532 in all stages. By doing that you will have no harmonics higher than -100dB with 0dB 1KHz signal applied, which makes the E1 a very transparent DAC.

 

[mBTX]

Hello,

OPA2604 was oscillating in both I/V and LPF stages, even if there was no plugs connected in RCA and XLR. It's more related to the PCB of the E1 and the power supply and grounding.
For safety and best measurements I can strongly recommend LME49720 and/or LM4562 and/or NE5532 in all stages. By doing that you will have no harmonics higher than -100dB with 0dB 1KHz signal applied, which makes the E1 a very transparent DAC.

Even over MUSES 01 in the I/V???

 

[raoultrifan]

Well, you can see the measurement on one of the above post, harmonics are a bit higher with MUSES01 than NE5532 when used in I/V: THD+N is 0.0067% with MUSES01 vs. 0.0024% with NE5532. Not something to complain about, but the difference is still there.

 

[mBTX]

Hmm, maybe I'll switch'em out. I've been having this issue where I get a bit of static after using the built in headphone amp after about 2 hours. Odd thing is if I tap the (2nd from right) I/V muses 01 it goes "bzzzzzt" and stops. I take it this is the grounding issues spoken of???

Thanks for your research and info, not only should it sound a little better, but it'll free up 4 01s for better uses!!!

 

[raoultrifan]

Hmmm...that's odd, maybe that specific opamp has an imperfect electrical contact on one pin. I suggest you to power off the device, take out the opamp, gently bend the 8 legs on the exterior for about 1/10 mm, then nicely re-insert it into the DIP8 socket and make sure you don't break anything in there. Basically, you need to ensure the opamp is not loosy or something.

BTW, are you 110% those 01s are genuine (just asking)?

 

[mBTX]

I bought them from digikey. They should be genuine. Any muses 01 or 02 opamps I get, I install in a riser socket. They're so soft that I'm afraid of snapping a leg. If they're that sensitive (connectivity wise) perhaps that could be my interference...

 

[Hopup]

I suppose it might be rather subjective what sounds better to each persons ears. I myself enjoy this dac more with tl072 in the outputs. I swear it sounds more detailed in this way, maybe its harmonic distortions or whatever.

 

[raoultrifan]

Might be the harmonics indeed, but might be something else...who knows... In the end what it matters is that this ASUS combo is still up and running after about 8 years and owners still love its sound, me included.

 

[r343]

I do like the E1 too, even it's kinda old at this moment. In single-ended I'm using the internal amplifier for headphones, but on the RCA plugs I have Mackie monitors connected.
The XLR balanced plugs are used in conjunction with Matrix HPA-3B, this way I can listen fully balanced from "head to tail".

Can you hear much difference in Essence Ones headphone output vs Matrix?

No clue how Essences headphone output performs against todays gear.