[drhiziracil]

To tell you the truth I don't know. I just saw muses01 name everywhere and its my first time to change an opamp. I just thought if a fake one is better than stock, original would do probably a lot better. May I ask what is the difference between a voltage or current feedback opamp? If other factors come in maybe I made a bad choice to change. I hope I don't end up blowing up my amp

 

[ginetto61]

Hi the difference between voltage and current type i do not know exactly. What i know is that with current feedback types there should be no capacitor in the feedback loop.
As i see some caps maybe they are of the voltage type.

 

[drhiziracil]

I'm sorry for being a noob. I tried to a little research but that topic is a little complicated to me for now. I have only listened my new fake amps for 1 hour now. I will give them a time for a little burning in. I mailed to mouser and waiting if they will answer to me about getting the original one. Do you think it would be better I would buy a different opamp?

 

[ginetto61]

First i would like to understand the circuit.
For instance, I see one opamp per channel just after the input so i guess these act as buffers.
Then 4 op following the volume pot, i guess. I do not know if they are paralleled or in series.
If so even just one op for channel (i.e. leaving one socket per channel empty) with a higher output current could work just fine.(Some opamps can drive many headphones without big troubles).
In general i do not like parallels of devices.
Better a single device per channel more robust.
I do not have access to the amp right now. It is stored away.
Read entirely this thread from the beginning. A guy did a very valuable testing using different opamps. It seems that this little but nice amp has a lot of potential indeed.
Maybe it is just a matter of picking the right opamps ?

P.S. just to add a trivial consideration. Often i have read about opamps not being the best devices for audio purposes. But it is a fact that some sublimely sounding audio equipment is based on opamps. So i guess it is more about how the opamps are actually used.
Another considerations. Also the quality of the passive parts sorrounding an opamp do matter. I mean high quality resistors and caps. They can improve an already good sound. I like for instance Dale and Holco resistors. Also because i have seen them in very high quality and price units.

 

[davidland]

thanks for sharing, I wanna make a tryout someday!

 

[drhiziracil]

So I finally got the original muses01 op-amps. It took only 3 days for them to come into my country but more than a week I dealed with the paperwork for custom clearence to get them.

Sound signature is pretty similar to the fake chinese muses01 opamps I'm really surprised that. But fake ones had so much distortion and lacked too much detail. But surprisingly fake ones had bass as good as original.

I have been using original ones only for 3 hours now. I will try to update after 2 weeks burn-in. Right now they are really warm. Actually the warmest I have ever heard, which I really like warm sound and hate bright sound. They have excellent bass. Really good detail and clearence and of course no distortion until %50 (I didnt try more than that it just hurts my ears). And this is the first time I have heard "S" and "T" sounds so natural. Sibilance usually draws my attention but with this ones I can hear none. Music is so sweet I just cant get tired from listening. But they seems to me a little behind from stock op-amps with the imaging. Stock op-amps almost had 3d sound to me I could tell what is right and what is left better with them. This might change with burning in.

VA1 DT/K stock op-amps are really good at clearence, detail, imaging and they have very low distortion. But they lack two things that take away the enjoyment from sound. They have bad bass and they are lifeless. Even when I connect my headphones directly out to my dac I get much more better bass. Stock op-amps are just killing the bass. But muses01 is upgrading the bass out of my dac, they have excellent bass. Stock op-amps are just no fun.

I gotta write something else about VA1. I have ordered them from US and they accept 110v but my country has 220v grid. So I had to buy a stepdown converter. First converter I bought was a cheap one and it had so much buzzing and humming so I was afraid I was gonna hear that sound from the amp. But once I listened the amp the buzzing from the outside was no issue. I mean this amp is really good at clearing the power. I changed the converter later for a good quality one. Even though I couldnt hear the buzzing/humming from the amp I was hearing from outside and it was pretty annoying.

By the way do you know if the output opamps are single or dual channel? I might try to change them someday

 

[drhiziracil]

Burson Audio has sent me a sample V5i for my honest review. I didn't compare them with the stock amps so I will do this here. And I will share further opinions about muses01 and stock opamps.

Firs I used V5i's in the input stage. I have tested them time to time for two weeks whilie burning in. They are really good opamps I can tell. They have better detail and clearness then muses01, being a little on the bright side but not harsh, and fast sound. They are producing percussions like sound excellent. But I think they are clipping the edges a little to do that. I compared it sound directly came out off may dac. And it seems they are faster then it is supposed to be. Imaging is better then muses01 too. Mids are a little dry to me. They both has excellent bass but muses01 goes just a little deeper. V5i has more tight bass

Muses01 was getting hot above %40-50 level. When they heat up they were messing the sound, by being muffled and distorted. V5i by the way giving their metal shield/heatsink they don't sweat even %60-70 level, so they they don't suffer like muses01 do.

I still prefer muses01 between two. It has more natural and warm sound. And I cant describe how but it has the "sweet" sound. But now this my preference is warm and darker sound.

After that trial I went back to muses01 in input stages and while I was back I wanted to try V5i's at the output stages. I only had two of them and they worked better even if without using the paralel amplification than stock opamps. The result was "wooow". Sound really became opened and much more alive. I usually listen rock with headphones but sometimes when I want to listen some bassy pop music I use my z623 2.1 speakers. Those speakers were a little back so not so much enjoyable. But with this combo they became so much alive I wanted to listen with them more. It had so much air and nice sparkle. But I mostly listen with my headphones and it was a little fatiguing for me. And lately I bought a new HD630VB which are a little on the bright side, they became more bright with this.

Then I returned to muses01 in the input stage and stock opamps at the output. Output stage stock opamps are a little laid back are more balanced and with the muses01 in the input they feel much natural. And since they are in warmer and darker area thats my taste. I dont think I will need to try any other opamp soon. I'm completely satisfied by the way for now. I still miss sometimes that nice lively sound on my z623 though.

Opamp and headphone match really matters as my experience show me. If you have a laidback gear a little bright opamp can make them shine. Or if you have bright warmer opamp takes away the fatiguing sound. SMSL VA1/DT stock input opamps were made for the bright beyer DT series headphones so they might have worked well with them. Actually those stock input opamps has better clearence, imaging and less distortion then the other two. But still they really lack bass and too lifeless.

EDIT: I'm just gonna post some pictures off them to show how they look for guide

 

[ginetto61]

Thank you very much indeed for the always very valuable testing and opinions.
Very trivially speaking I guess that listening fatigue should be the effect of some kind of distortion going on.

From your words I understand that the output stage after the volume control is actually realized with two identical op-amps in parallel. In general i am not a fan of parallels and I really do not understand why they have decided for this more complex solution given that powerful op-amps able to output good current are available. However if you say that they sound good and natural that ends the issue.

Regarding the input buffer OAs by the way I am a little confused about the bass issue.
The input buffers have just to drive the volume pot that should be at least 10k Ohm and almost purely resistive. I can understand a better clarity probably resulting from a lower THD opamp but the bass we perceived through the headphones is provided by the output stage.
Therefore changing the input buffers but leaving the same output stage should result in very similar bass response.

Again I think that it would be extremely helpful to be able to extract the schematic before swapping op-amps. (I do not think that SMSL audio would provide that unfortunately).

I am pleased to know that the amp is fundamentally well designed and made.
And that very good sound can be obtained even with OAs.
I would try the one OA solution at the output and maybe other OA as input buffers to achieve a greater clarity.
But without a schematic I am quite scared to move on.
For instance sometimes what sounds like distortion is actually an OA oscillating and that can get damaged very quickly.

I do not even know if the six stock OAs are all equal, or if they are voltage feedback or current feedback types.

Putting a CF unit in a circuit good for VF opamps can make a disaster. I did it once and ruined everything.
I am very ignorant on the issue.
Thanks a lot again.
Kind regards, gino

 

[drhiziracil]

Well I dont know about the specs but for the input bass response is immediately noticeble. I also use z623's subwoofer to have better view of bass response. And I also use rca to 3.5 mm jack cable directly out of my dac to compare and see the coloration of the amp. That stock VMV DT/K input opamps definitely has low bass.

I agree with you if smsl shared the schematics it would be really helpfull. But we are unlucky in that area.

Clarity; I can definitly say in my experience they have so much better clarity with stock OA compared the other two. But input VMV DT/K are the main culprit. Output OA's are really good as they are.
I didn't hear any distortion actually I'm a little sensitive to bright sound. I like bright sound actually but I can't listen to them for longer sessions. My preference is warmer and darker sound. Muses01 goes into distortion after they warm up even at %40-50 levels. Stock and V5i didn't show that issue. But I don't know osciliation sound, I cannot commend on that

I don't think all six stock are equal for sound but I cannot speak if they are voltage feedback or current feedback. Because I don't have experience much in that area. I'm more ignorant than you

Best regards, drhiziracil

 

[ginetto61]

Well I dont know about the specs but for the input bass response is immediately noticeble.
I also use z623's subwoofer to have better view of bass response. And I also use rca to 3.5 mm jack cable directly out of my dac to compare and see the coloration of the amp.
That stock VMV DT/K input opamps definitely has low bass.

Hi again, i see. I like also very much strong and firm bass of course. It gives a sort of foundation to the sound.
It is also the reason because when i listen to maybe nice but small bookshelf speakers i feel i miss something.
The sound is not complete.

I agree with you if smsl shared the schematics it would be really helpfull. But we are unlucky in that area.

yes but this is just normal. Brands are rightly jealous of their products. Also the OAs are without marks.

Clarity; I can definitly say in my experience they have so much better clarity with stock OA compared the other two. But input VMV DT/K are the main culprit. Output OA's are really good as they are.
I didn't hear any distortion actually I'm a little sensitive to bright sound. I like bright sound actually but I can't listen to them for longer sessions. My preference is warmer and darker sound. Muses01 goes into distortion after they warm up even at %40-50 levels. Stock and V5i didn't show that issue.
But I don't know osciliation sound, I cannot commend on that
I don't think all six stock are equal for sound but I cannot speak if they are voltage feedback or current feedback. Because I don't have experience much in that area. I'm more ignorant than you
Best regards, drhiziracil

Very good to know that the output pairs are just fine. This make the upgrade task easier indeed.
So in the end are you planning to leave the Muses01 in the input stage ?
Are they expensive ? i could give them a try.
Thanks a lot again. gino
P.S. i found the Muses01 ... almost 50 euro /each ... quite expensive. I will read about them and possible alternative also nice but cheap.

Already found something about them:
https://www.amazon.com/product-revi...=UTF8&filterByStar=five_star&showViewpoints=0

and another document mentions some possible alternatives: TL072, NE5532, LM4562, OPA2604, OPA2134, OP275, MUSES 02, MUSES 8820, MUSES 8920, OPA2228.

 

[drhiziracil]

Well I'm gonna try V5i's in the output stage a little more. To see if I can get use to that little bright sound. When muses01 at the input and V5i at the output sounds seem to have more energy, dynamic, open, air and fun. But just fatiguing in longer listening sessions. If I can't get use to I'm gonna stick with the muses01 at the input stage while stocks at the output

I actually even bought that high quality, cables, power adapters etc.. They did cost close to muses01 but none of them did make a change like muses01. And I know myself if I wouldn't satisfied with the cheaper alternatif. I probably would try higher and higher and in the end I would have spend much more. So I decided why not go for a one really good, rather than trying all the way to there. I can speak for myself that they are worth the price.

I don't know those other alternatives since I don't have experience with them. I don't want to buy any other new opamp soon but I will look into them when I wanna want a change (if I want a change)

 

[ginetto61]

Hi ! i think that to allow the parts to break in is very important. I have some experience with gear that was bright at first and then smoothed out. I would say that 200 hours of use should be enough.
I have found a youtuber who has uploaded interesting video on opamps swapping tests.



Please let us know about how the break in will go. The Burson must be really something. When many sources agree with the high quality of a part chances are that the part is really really good. When used right of course.
Kind regards, gino

 

[drhiziracil]

Well I actually burned in them almost 100 hours but that brightness didn't go away. They are not "too bright" just a little bright. It's actually quite enjoyable for short listening sessions but fatiguing for long. I was testing with the new opamps and my new HD630VB too much I got an irritating tinnitus. And I'm gonna rest my ears for 2 weeks before starting to test them again. They will be burned in by that time

Besides listening music I use my set up for regular pc usege for watching movies, playing games etc.. And I got eq down at 8 khz -3db and 16 khz -7db with those bursons at the output. Otherwise I can't stand them to use for regular usage. With stock opamps at the output I don't need to use eq.

I'm not sure that video is helpfull for comparing opamps. I think you have to listen to them while they are in your amp otherwise it won't be a healty comparation. But still 8920 sounded nice to me while 275 sounded bad

Once I rest my ears I'm gonna share my impressions. And I will decide if I will keep them or not

Kinds regards, drhiziracil

 

[ginetto61]

Hi ! i have a personal method to check for listening fatigue from a system.
I usually play this old cd here:

very well recorded with a lot of high level music of trumpets.
If the system is bright it hurts. I have to turn the volume down.
But if the system is good it sounds unbelievably dynamic and wonderful. Very live. Very real.
And i want to turn the volume up.
Especially for solid state equipment this disc is a tough test indeed.
IMHO brightness could come from some kind of distortion. A real trumpet is always listenable in reality. And so it should be when recorded.

 

[drhiziracil]

There might be distortion I couln't notice but still bright sound bothers me even without distortion. But yet with distortion in those high frequencies I couln't hear it would probably disturbing more.

By the way I couldn't stand that brightness so I returned to stocks output because with HD630VB is a little bright its unbearable. But with the laid back z623 they were really good with music (not with regular usage).

Before I returned to stocks I tried those stock input VMV DT/K input opamps at the output. And by doing that I can say for sure they are different. And the stock input ones really lack bass. But they were cleaner and had more detail than those stock outputs. (Muses01 were always at input while trying that)

I also tried my fake chinese muses01 at the output with real ones at the input. Fake ones has really similar sound signature to real ones but they have too much distortion. I wanted to see what would the coloration of the sound look like. Bass became overpowerfull. There was nice but a little much colaration of sound but I still preferred stock ones at the output.

Stock output opamps are more natural, balanced and colorless than compared to all others I have tried. And for my preference just the muses01 at the input stage has enough coloration with the stock ones at the output. Output ones are a little laid back but they are a better match for my little bright HD630VB.

I want to put one more little note. I have read about how bass would be affected if you connect a low impedance to a high impedance output. I haven't seen these my other headphones before but with HD630VB there is a huge difference in sub bass between high and low outputs. High output has much lower sub bass