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Xduoo MT-604 tube rolling hints?

Ishka

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Any recommendations for tube rolling for this amp? Also, recommendations for pairing with a DAC?
 

DVDdoug

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I don't know...

Even tubes with the same part number from the same tube manufacturer will vary and you can't buy tubes with tight tolerances like you can buy 1% (or better) resistors.

A well designed amplifier's specs/performance won't be affected by normal tube variations (so every amp coming if the assembly line will be the same) and it won't change as the tube ages until the tube ages beyond it's useful life.

And, a good high fidelity amplifier won't have a "tube sound" or a "MOSFET sound". The ideal is a "straight wire with gain" (flat frequency response, no audible noise, no audible distortion). Some people might prefer a particular kind of tube-distortion, but that's a personal preference thing and every amp that's not high-fidelity will sound different from any other amp that's not high fidelity so you might like one tube amp but not another.

Transistors, MOSFETs, and ICs also have part-to-part variations (but they don't "age") so amplifiers (and other electronics) are designed so these variations don't affect performance, as long as the parts are in-spec and not defective.
 
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Ishka

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Thank you for the primer on tubes... you're obviously way more technical than myself. One thing is interesting, though. This amp sounds better to me on a less expensive balanced GRACE DAC than it does on a more expensive SMSL DAC... I can't figure that one out? Thanks again...
 

Chilli

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Any recommendations for tube rolling for this amp? Also, recommendations for pairing with a DAC?

Hi Ishka,

The 6j1 supplied with this amp are described to be working well, and subjectively they apparently sounded more correct.
Most usually try out the 5654w.
I have one of these ordered to use as a preamp volume control before my power amps. Its cheap and appears to be a hybrid.. Just not sure how much the tubes are involved, as the power is coming from class A devices, rather than from the tubes. That said, even with the tubes in a buffer, its likely to have some effect on the sound.
There are some specifications supplied, but not enough to know exactly things will match up. However, i suspect the quality of dacs today are so good, you have a large selection and probably cant go far wrong with some of the good performing and cheap dads you can find measured on this website.
If you live in the US, i did see a good website called Riverstone, who can get you a matched pair of 5654w if you wish. The guy on there appears to have some good tube testers, including a Chinese tube tester, which i believe is well regarded.
 

SeriousApple

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I like chinese 6J5 tubes they are really dynamic lot of sound stage and tuby sound. Love it. Might be too tuby for you. You Can also try GE 5654 tubes if you want more neutral sound. Also pair with AKM balanced dac will give you good synergy with tubes. All the best.
 

Sigfried

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Jan 12, 2022
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Hi Ishka,

The 6j1 supplied with this amp are described to be working well, and subjectively they apparently sounded more correct.
Most usually try out the 5654w.
I have one of these ordered to use as a preamp volume control before my power amps. Its cheap and appears to be a hybrid.. Just not sure how much the tubes are involved, as the power is coming from class A devices, rather than from the tubes. That said, even with the tubes in a buffer, its likely to have some effect on the sound.
There are some specifications supplied, but not enough to know exactly things will match up. However, i suspect the quality of dacs today are so good, you have a large selection and probably cant go far wrong with some of the good performing and cheap dads you can find measured on this website.
If you live in the US, i did see a good website called Riverstone, who can get you a matched pair of 5654w if you wish. The guy on there appears to have some good tube testers, including a Chinese tube tester, which i believe is well regarded.
Hi Chilli, I own the MT604 and primarily just use it as a headphone amplifier. I have heard elsewhere that it can be run as a preamp before an amp. Then i see your response and you also are doing this. My question is, how do you make the connections to your amplifier? I only see balanced in (xlr) connection on the back and another balanced in (4.4mm) on the front. I am really enjoying it as a headphone amplifier and would really be interested to hear how it would sound as a possible tube buffer/preamp. Thanks!
 

Chilli

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Hi Chilli, I own the MT604 and primarily just use it as a headphone amplifier. I have heard elsewhere that it can be run as a preamp before an amp. Then i see your response and you also are doing this. My question is, how do you make the connections to your amplifier? I only see balanced in (xlr) connection on the back and another balanced in (4.4mm) on the front. I am really enjoying it as a headphone amplifier and would really be interested to hear how it would sound as a possible tube buffer/preamp. Thanks!
i have the mt602, not the mt604. The 602 can be used as a preamp, but not the 604. Perhaps it might be possible with a transformer air gap between, but I’m not sure. You would need to buy a transformer to transformer isolation prior to the amplifier. I did this for the e1da 9038s and it worked. However, it would be easier to buy an Mt602 instead. I am using the mt602 with either ncore amps or with hifiman he400se. It’s great. I have a few different tubes to try out but I don’t expect to hear much difference. We shall see.
 

Sigfried

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i have the mt602, not the mt604. The 602 can be used as a preamp, but not the 604. Perhaps it might be possible with a transformer air gap between, but I’m not sure. You would need to buy a transformer to transformer isolation prior to the amplifier. I did this for the e1da 9038s and it worked. However, it would be easier to buy an Mt602 instead. I am using the mt602 with either ncore amps or with hifiman he400se. It’s great. I have a few different tubes to try out but I don’t expect to hear much difference. We shall see.
Thank you! I just asked this question on Amazon and some guy responded that i could use the XLR out to an amplifier.....? I think i will trust your opinion since you are on this forum and probably know a lot more than some random guy answering my query on Amazon. :/

Btw....i did try Riverstone's GE5654's on the 604 and I didn't find much of a difference over stock. Slightly maybe they were better but not much. Then i tried some Sylvania 6AK5's from 1953. They provided an improvement in tone to my ears for certain. Richer sounding i would say. Pleased with that swap. Thanks again!
 
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