Cayin RU6: R-2R USB Dongle DAC with Head-Amp
Jul 31, 2022 at 8:12 PM Post #2,701 of 3,685
Only used mine at home so far but I noticed my RU6 gets much hotter in oversampling mode.
What causes heating...

I am not overly concerned about excessive heat causing any damage, but I am still trying to undersand the causes. Further experiments with four different headphones. PC > RU6 (NOS, High gain)...

Playing balanced vs single ended (4.4mm vs. 3.5mm). RU6 gets slightly warmer playing from the balanced amps (4.4mm)

With Tidal, playing at 44.1 Khz it gets warm. E.g. Allison Krauss, Forget About It.
Playing a "Master" track at 96khz, it gets much warmer. E.g. Allison Krauss Windy City. With this album the Grado SR325is balanced out is the hottest.

So, balanced out and high sampling rates ==> RU6 runs hotter.

@gr8soundz reports heating when in OS mode.


Anyone else been able to pinpoint the cause(s) of heating?
 
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Jul 31, 2022 at 11:00 PM Post #2,702 of 3,685
What causes heating...

I am not overly concerned about excessive heat causing any damage, but I am still trying to undersand the causes. Further experiments with four different headphones. PC > RU6 (NOS, High gain)...

Playing balanced vs single ended (4.4mm vs. 3.5mm). RU6 gets slightly warmer playing from the balanced amps (4.4mm)

With Tidal, playing at 44.1 Khz it gets warm. E.g. Allison Krauss, Forget About It.
Playing a "Master" track at 96khz, it gets much warmer. E.g. Allison Krauss Windy City. With this album the Grado SR325is balanced out is the hottest.

So, balanced out and high sampling rates ==> RU6 runs hotter.

@gr8soundz reports heating when in OS mode.


Anyone else been able to pinpoint the cause(s) of heating?

I'm usually in Low Gain mode, NOS, average volume around 80, using balanced out and mine still runs fairly cool (even with the case on). Have a number of hi-res albums but most of my collection is 16/44 so I'll let others chime in about running at High Gain with hi-res via balanced.

However, can't overlook the fact of just how much Cayin packed into this little guy. The RU6 has 2 double-sided PCBs inside, giving it roughly 2-4x more components than other (non-discrete) dongles so its bound to run warmer.

Recently found this teardown of the RU6 which shows it better:
http://audiotop.net/newsinfo/2524361.html

RU6teardown.jpg
 
Aug 1, 2022 at 12:17 PM Post #2,703 of 3,685
What causes heating...

I am not overly concerned about excessive heat causing any damage, but I am still trying to undersand the causes. Further experiments with four different headphones. PC > RU6 (NOS, High gain)...

Playing balanced vs single ended (4.4mm vs. 3.5mm). RU6 gets slightly warmer playing from the balanced amps (4.4mm)

With Tidal, playing at 44.1 Khz it gets warm. E.g. Allison Krauss, Forget About It.
Playing a "Master" track at 96khz, it gets much warmer. E.g. Allison Krauss Windy City. With this album the Grado SR325is balanced out is the hottest.

So, balanced out and high sampling rates ==> RU6 runs hotter.

@gr8soundz reports heating when in OS mode.


Anyone else been able to pinpoint the cause(s) of heating?
Now more confused than ever…. Today my Grado SR325 (balanced) listening to the same 96 Khz album, out of my iPad pro…. No heating at all… room temp. Same with 88.2 Khz tracks.
💁
 
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Aug 2, 2022 at 6:49 AM Post #2,704 of 3,685
RU6 overheating with Grados???

I am using RU6 NOS, High Gain, 29db volume in all these use cases...

iPad Pro > Tidal > RU6 4.4mm balanced > Focal Elegia (Fluke meter 31.2 ohms)
With the Focals the RU6 just gets a bit warm.

iPad Pro > Tidal > RU6 4.4mm balanced > Grado SR325is (Fluke meter 34.2 ohms). Grados modified to use Meze 4.4mm balanced "silver" cable (1 ohm).
With the Grados the RU6 gets hot within 5 minutes. I can hold it in my hand, but it's pretty hot.

I also notice that on my desktop PC > RU6 > Grados, playing the same album in HiFi (from Foobar2000) and Tidal Master:
44.1Mhz, RU6 gets warm.
88.2 Mhz RU6 gets hot.

With the Focals it's just a little bit warmer playing the "Master" version.

Anyone else notice this?
Would +4 ohms draw that much more power?
Does it take more power to process 88.2 Mhz?

Any ideas?

Thanks
New test…
iPad > RU6 3.5mm > Oppo PM-3. 39db volume. Tidal “HiFi”. 88.2 Mhz. Does not even get warm.

Can anyone from Cayin step in and tell us what causes the RU6 to heat up, and more importantly at what temperature will the device be damaged??
What causes heating...

I am not overly concerned about excessive heat causing any damage, but I am still trying to undersand the causes. Further experiments with four different headphones. PC > RU6 (NOS, High gain)...

Playing balanced vs single ended (4.4mm vs. 3.5mm). RU6 gets slightly warmer playing from the balanced amps (4.4mm)

With Tidal, playing at 44.1 Khz it gets warm. E.g. Allison Krauss, Forget About It.
Playing a "Master" track at 96khz, it gets much warmer. E.g. Allison Krauss Windy City. With this album the Grado SR325is balanced out is the hottest.

So, balanced out and high sampling rates ==> RU6 runs hotter.

@gr8soundz reports heating when in OS mode.


Anyone else been able to pinpoint the cause(s) of heating?
Now more confused than ever…. Today my Grado SR325 (balanced) listening to the same 96 Khz album, out of my iPad pro…. No heating at all… room temp. Same with 88.2 Khz tracks.
💁

First of all, there is no need to worry that RU6 will be damaged by heat basic on your description. The thin film resistors are good for 100°C or above, and other electronics and semiconductors are good for 80°C or above. If you can hold it in my hand, the device probably is around 45°C, well within the operation margin of RU6.

I tested my RU6 with the following setting: Samsung A71 > HiBy Music Player at Exclusive mode, 24Bit/96kHz local music file > RU6 (NOS, High gain, Vol=70). I used Gardo RS1 from the single-ended 3.5mm phone out of RU6.

I didn't find it warmer than my regular RU6 usage. I can't test the 4.4.mm phone out because I didn't mod my Gardo, so I can't call this a replicate of your setup. At this stage, we can't explain the "excessive" heat problem until we can replicate a particular scenario when the RU6 suddenly heated up as you described.

RU6 with Gardo 96kHz.jpg

t
 
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Aug 2, 2022 at 7:06 AM Post #2,705 of 3,685
First of all, there is no need to worry that RU6 will be damaged by heat basic on your description. The thin film resistors are good for 100°C or above, and other electronics and semiconductors are good for 80°C or above. If you can hold it in my hand, the device probably is around 45°C, well within the operation margin of RU6.

I tested my RU6 with the following setting: Samsung A71 > HiBy Music Player at Exclusive mode, 24Bit/96kHz local music file > RU6 (NOS, High gain, Vol=70). I used Gardo RS1 from the single-ended 3.5mm phone out of RU6.

I didn't find it warmer than my regular RU6 usage. I can't test the 4.4.mm phone out because I didn't mod my Gardo, so I can't call this a replicate of your setup. At this stage, we can't explain the "excessive" heat problem until we can replicate a particular scenario when the RU6 suddenly heated up as you described.


t
Thanks for taking the time to run your test. I will report back if I run into another use case that causes the RU6 to heat up.

It is good to know the device can run hot without damage.
 
Aug 2, 2022 at 2:29 PM Post #2,706 of 3,685
Just added a 3' Apple Lightning to USB-C OTG cable to the setup. Really like having my iDevice on a stand or on my lap, which with the Cayin purchased cable...puts the RU6 either in the way or has it hanging oddly off to the side when in landscape viewing/listening mode (adding unnecessary strain/pressure on the lightning connector in general).

Movies/soundtracks are also awesome with the Cayin RU6!
 
Aug 11, 2022 at 2:02 PM Post #2,708 of 3,685
Thanks for taking the time to run your test. I will report back if I run into another use case that causes the RU6 to heat up.

It is good to know the device can run hot without damage.
RU6 HEATING UP - USE CASE

I found a strange use case that really heats up the RU6....

Testing two pairs of Grados (SR325is and SR325x). One with 3.5mm cable, and one with 4.4mm balanced cable.
Constantly switching the head phones caused the RU6 to really heat up.

Now I unplug the RU6 from my USB source before switching headphones. The RU6 is slightly warm, no problem.

EDIT: note that the same use case causes my Fiio M11 Pro to really overheat as well.
 
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Aug 11, 2022 at 5:05 PM Post #2,709 of 3,685
How do you guys compare dongles? Currently I am using PC->RU6 (low gain, NOS) vs PAW S1 (low gain) -> Z1R. I tried EDM, male and female vocal, very briefly but I just cannot find any difference.
 
Aug 11, 2022 at 6:15 PM Post #2,710 of 3,685
Aug 12, 2022 at 5:53 PM Post #2,711 of 3,685
Had the screen come off recently. Possibly the heat wave we’ve been experiencing. Idk. I might have to send this unit to musicteck if they are cool with it for a replacement.
 

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Aug 12, 2022 at 7:11 PM Post #2,712 of 3,685
I will be getting home after a few months of touring and I have one of the RU6s waiting for me to give it a whirl. I'm stoked to see what this dongle has up its sleeve for sure!
 
Aug 13, 2022 at 7:49 PM Post #2,713 of 3,685
I have been using RU6 for a few days now and my intention is to get a "feel" of the musicality of R2R to help me make a choice between Hiby RS2 and iBasso DX170.

Today I did a quick A/B test using RU6 as DAC to compare Schiit Modi3, other in the chain is PC -> RU6/Modi3 -> FA-10 -> HE6SE V2. RU6 is in NOS high-gain mode. An apparent difference is the low-end, bass is much more punchy with Modi3. This leads me to suspect that R2R based dongles or DAPs may have weakness in bass performance.
 
Aug 13, 2022 at 8:04 PM Post #2,714 of 3,685
I have been using RU6 for a few days now and my intention is to get a "feel" of the musicality of R2R to help me make a choice between Hiby RS2 and iBasso DX170.

Today I did a quick A/B test using RU6 as DAC to compare Schiit Modi3, other in the chain is PC -> RU6/Modi3 -> FA-10 -> HE6SE V2. RU6 is in NOS high-gain mode. An apparent difference is the low-end, bass is much more punchy with Modi3. This leads me to suspect that R2R based dongles or DAPs may have weakness in bass performance.
Really!! I'm very surprized by your statement. RU6 has a lot of bass, sometimes I even find it too much. It is just not as fast as delta sigma DACs but in terms of quantity it is way enough
 
Aug 13, 2022 at 9:38 PM Post #2,715 of 3,685
Really!! I'm very surprized by your statement. RU6 has a lot of bass, sometimes I even find it too much. It is just not as fast as delta sigma DACs but in terms of quantity it is way enough
It depends on what you are pairing it with, on some of my gear, I notice quicker bass roll off and on others I don't.

Today I did a quick A/B test using RU6 as DAC to compare Schiit Modi3, other in the chain is PC -> RU6/Modi3 -> FA-10 -> HE6SE V2. RU6 is in NOS high-gain mode. An apparent difference is the low-end, bass is much more punchy with Modi3
For me, the bigger change I noticed between RU6 and some of my other DS dongle DACs was in the mids. Mids on RU6 have good body and more organic tonality.
 

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