[CADCAM]

Which pairs best with HD6XX Sylvania or Russian tubes?

Out of my current crop my favorite is the 1969 Sylvania 5654, which I believe, (it's so hard to evaluate) sound superior to the 1967 Sylvania's that were my previous favorite. Either one sounds better than anything else I've tried which include the GE 5654. The only tube I haven't tried yet in my 602 is the Tung-Sol 6AK5W mainly because I'm not sure I'd be able to get it out, they are short!

 

[CADCAM]

Just got another pair of the 69' Sylvania's, these must have been sitting in the boxes since 69' because the boxes are like new except for fading from age and the tubes look new. Printing on tube was perfect but unfortunately the pins were very oxidized and no matter how careful you are some of the printing gets damaged during the cleaning process you have to hold the thing to clean it!
Anyway... going to try them at home later on the MT-602 and hopefully they sound as fantastic as the last pair

 

[Wiljen]

Thanks!
is the filament supply AC? or DC? regulated? or not? .

I got a thorough tear down and took some photos and on tracing the pins the Heaters are AC powered and not DC. Glad I went back and checked because my initial thought was incorrect.

I'll post teardown shots in the review so you can see boards in them.

 

[dsrk]

MT-602 pairs well with Ananda, I like it better than HD6XX + MT-602.

 

[tkddans]

Just got a MT-604 review unit from Apos, a loaner I have to give back, and I’m honestly getting strong out of the box impressions with sound quality.

Plus, it doesn’t hurt that they have a very pleasant color coming through the tubes more than the TA-30 I have, at any angle I try to look between the two. Now, I do wonder if that glow is purely due to lights installed, and not actually tubes warming up (since, when I turned on the 604, the orange light was IMMEDIATELY brightly glowing; and tubes need time to warm up and glow brighter, in past experiences with my TA-30). Or maybe the filaments are just genuinely glowy? I gotta switch tubes to see what happens, but I think it’s just lights. Still very pretty!

I normally use a Xduoo TA-30 ($700 retail, often $600 on Drop), so my point of comparison is pretty strong already. Not to mention, my TA-30 has maybe $100 or more of tube replacements.

And yet, even before tube rolling the 604, I’m almost not inclined to bother switching them out to say that I enjoy what I get from it. And the thing is only what…$170? I gotta check the site for price again but I think that’s right (I’m on my phone and lazy right now ok?!) haha

I was only going to make an impressions video, but now I feel I have to record full fledged demos of the 604 with stock tubes, my TA-30 with my favorite tubes, and the 604 with those same favorite tubes. I gotta share sound samples in a video so people can hear for themselves what I’m hearing - that is, this cheap entry level priced tube amp may just be the best bang for the buck.

The only caveat may be, and I haven’t discovered yet if this is true, that the 604 may not respond to tube rolling as noticeably as the TA-30, because the 604 is not a full tube amp but a hybrid solid state and tube. Amps with solid state components are said to be less “tubey” than pure tube driven gear.

More thoughts to come in an official video review with demos!!

EDIT: Just occurs to me that my other tubes are too big, I think, for the 604. Does anyone have recommendations for these smaller tube slots?

 

[jsmiller58]

Just got a MT-604 review unit from Apos, a loaner I have to give back, and I’m honestly getting strong out of the box impressions with sound quality.

Plus, it doesn’t hurt that they have a very pleasant color coming through the tubes more than the TA-30 I have, at any angle I try to look between the two. Now, I do wonder if that glow is purely due to lights installed, and not actually tubes warming up (since, when I turned on the 604, the orange light was IMMEDIATELY brightly glowing; and tubes need time to warm up and glow brighter, in past experiences with my TA-30). Or maybe the filaments are just genuinely glowy? I gotta switch tubes to see what happens, but I think it’s just lights. Still very pretty!





I normally use a Xduoo TA-30 ($700 retail, often $600 on Drop), so my point of comparison is pretty strong already. Not to mention, my TA-30 has maybe $100 or more of tube replacements.

And yet, even before tube rolling the 604, I’m almost not inclined to bother switching them out to say that I enjoy what I get from it. And the thing is only what…$170? I gotta check the site for price again but I think that’s right (I’m on my phone and lazy right now ok?!) haha

I was only going to make an impressions video, but now I feel I have to record full fledged demos of the 604 with stock tubes, my TA-30 with my favorite tubes, and the 604 with those same favorite tubes. I gotta share sound samples in a video so people can hear for themselves what I’m hearing - that is, this cheap entry level priced tube amp may just be the best bang for the buck.

The only caveat may be, and I haven’t discovered yet if this is true, that the 604 may not respond to tube rolling as noticeably as the TA-30, because the 604 is not a full tube amp but a hybrid solid state and tube. Amps with solid state components are said to be less “tubey” than pure tube driven gear.

More thoughts to come in an official video review with demos!!

EDIT: Just occurs to me that my other tubes are too big, I think, for the 604. Does anyone have recommendations for these smaller tube slots?

Definitely LEDs under the tubes, but looks great!

This link gives some suggestions for tubes - https://audiofool.reviews/tube-rolling-the-xduoo-mt-604/

 

[CJG888]

Just got a MT-604 review unit from Apos, a loaner I have to give back, and I’m honestly getting strong out of the box impressions with sound quality.

Plus, it doesn’t hurt that they have a very pleasant color coming through the tubes more than the TA-30 I have, at any angle I try to look between the two. Now, I do wonder if that glow is purely due to lights installed, and not actually tubes warming up (since, when I turned on the 604, the orange light was IMMEDIATELY brightly glowing; and tubes need time to warm up and glow brighter, in past experiences with my TA-30). Or maybe the filaments are just genuinely glowy? I gotta switch tubes to see what happens, but I think it’s just lights. Still very pretty!





I normally use a Xduoo TA-30 ($700 retail, often $600 on Drop), so my point of comparison is pretty strong already. Not to mention, my TA-30 has maybe $100 or more of tube replacements.

And yet, even before tube rolling the 604, I’m almost not inclined to bother switching them out to say that I enjoy what I get from it. And the thing is only what…$170? I gotta check the site for price again but I think that’s right (I’m on my phone and lazy right now ok?!) haha

I was only going to make an impressions video, but now I feel I have to record full fledged demos of the 604 with stock tubes, my TA-30 with my favorite tubes, and the 604 with those same favorite tubes. I gotta share sound samples in a video so people can hear for themselves what I’m hearing - that is, this cheap entry level priced tube amp may just be the best bang for the buck.

The only caveat may be, and I haven’t discovered yet if this is true, that the 604 may not respond to tube rolling as noticeably as the TA-30, because the 604 is not a full tube amp but a hybrid solid state and tube. Amps with solid state components are said to be less “tubey” than pure tube driven gear.

More thoughts to come in an official video review with demos!!

EDIT: Just occurs to me that my other tubes are too big, I think, for the 604. Does anyone have recommendations for these smaller tube slots?

Isn’t the TA-30 a hybrid too?

 

[tkddans]

Isn’t the TA-30 a hybrid too?

Oh you’re right! Silly me

but it does have a rectifier tube and the transformer in the back. I’m not an expert on how the circuitry differences play out exactly, etc etc.; though would it be true that the addition of the large transformer and rectifier in the circuit path mean that there could be more opportunity for sound to be affected by those additions to the unit, compared to the 604?

I wish I had smaller tubes to roll out with the 604 and see how much different I could make the sound appear.

I know that with my TA-30, I hear the sound change between tubes quite audibly. But with the 604, I can’t say right now since I don’t have the tubes to try.

I just assumed that the additional components on the 30 meant for greater leeway for rolling and for different experiences, but hey I don’t actually know for sure if it’ll be so different than what’s possible on the 604 without rectifier and transformer.

Thanks for pointing it out!

 

[AudioCats]

I got a thorough tear down and took some photos and on tracing the pins the Heaters are AC powered and not DC. Glad I went back and checked because my initial thought was incorrect.

I'll post teardown shots in the review so you can see boards in them.

Thanks. Any idea what the heater voltage is?

 

[Wiljen]

Thanks. Any idea what the heater voltage is?

mine measures at 6.26-6.28V when in operation. Had to wire an adapter to get a multimeter on the pins.

 

[AudioCats]

Thanks.
That is perfect filament voltage, wow.

 

[AudioCats]

ta-26 is now on sale, 10% off.
$287 is still a good chunk of change, though.

 

[Wiljen]

Thanks.
That is perfect filament voltage, wow.

Yeah it seems to be a pretty well designed amp from the measurements. It won't please the DIY crowd at all as the crack and DV336 are much easier to tinker on, but it does provide a finished product for less $ than a crack that comes closer to rivaling the finished crack/speedball than the DV does without pushing the price to double that of the base model.

 

[AudioCats]

the TA26 enclosure is a bit on the narrow side but workable. If it is 1" wider that would be perfect. Tube combination is good, and the metal case helps heat dissipation.

I am mainly curious of whether (after removing the output capacitors) there will be enough room in the TA26 for HV regulation (heat dissipation ~ 3w), filament power management, and maybe even CCS for output (replacing the 1k resistors).

BHC and DV enclosures are larger, but still not big enough. To do it right, output capacitor banks will need to be in a separate box anyway.

 

[Wiljen]

the TA26 enclosure is a bit on the narrow side but workable. If it is 1" wider that would be perfect. Tube combination is good, and the metal case helps heat dissipation.

I am mainly curious of whether (after removing the output capacitors) there will be enough room in the TA26 for HV regulation (heat dissipation ~ 3w), filament power management, and maybe even CCS for output (replacing the 1k resistors).

BHC and DV enclosures are larger, but still not big enough. To do it right, output capacitor banks will need to be in a separate box anyway.

Its going to be a tough case to work in as there isn't much room. I suspect any major upgrade is going to require case replacement as part of the process.