[Thomastb]

For #1 - Back in 2021, I noticed that the supply of JAN5899 tubes had "dried up", and the portable amp manufacturers had switched to JAN5784 tubes.
I posted about it on Page 45 of this thread - https://www.head-fi.org/threads/portable-tube-amp-from-china.626237/post-16095516

For #2 - The TAP-1S is fully balanced, and has signal phase splitters, which allow either single-ended or differential inputs to produce either single-ended or differential outputs. This is unlike some other portable amps which will only produce the output that's the same as the input. The TAP-1S also has the External "Desktop" Power Supply, which allows it to produce almost 2.5W/ch output. The TAP-2 produces 0.5W/ch output.

For #3 - I don't have any OPA2132 op-amps, but I do have MUSES02 op-amps, and suspect that the MUSES02 would have a "warmer" sound.

For #4 - If I didn't need balanced output, and wanted a small tube hybrid Amp - for convenience of use, I would select the TAP-2 - since it uses a standard USB-C for charging, and the B4-X uses a special 12.6V Lithium-Ion charger. The B4-X can not be used while it's charging - when the 12.6V input is connected, a relay disconnects the DC-DC supplies that power the tubes & op-amps, so the battery can be charged.

Thanks for your amazing detailed explanation, I'm very grateful and impressed.
So between b4 x and tap2:
1. B4 X I manage to speak to the shop and they can modify it where it can be used while charging at the same time. The only concern is noise. Does tap2 have noise when in use? (during charging and not charging)
2. I'm able to find USB to12.6V charging cable. That solves the portable issue too.

So base on these info, any other things that may separate the two? Such as more power, better tube sound, better layering/soundstage?

I can see both device can be opened and change Op amp.

 

[Thomastb]

For #1 - Back in 2021, I noticed that the supply of JAN5899 tubes had "dried up", and the portable amp manufacturers had switched to JAN5784 tubes.
I posted about it on Page 45 of this thread - https://www.head-fi.org/threads/portable-tube-amp-from-china.626237/post-16095516

For #2 - The TAP-1S is fully balanced, and has signal phase splitters, which allow either single-ended or differential inputs to produce either single-ended or differential outputs. This is unlike some other portable amps which will only produce the output that's the same as the input. The TAP-1S also has the External "Desktop" Power Supply, which allows it to produce almost 2.5W/ch output. The TAP-2 produces 0.5W/ch output.

For #3 - I don't have any OPA2132 op-amps, but I do have MUSES02 op-amps, and suspect that the MUSES02 would have a "warmer" sound.

For #4 - If I didn't need balanced output, and wanted a small tube hybrid Amp - for convenience of use, I would select the TAP-2 - since it uses a standard USB-C for charging, and the B4-X uses a special 12.6V Lithium-Ion charger. The B4-X can not be used while it's charging - when the 12.6V input is connected, a relay disconnects the DC-DC supplies that power the tubes & op-amps, so the battery can be charged.

Other than that do u know anything about the adv portable tube? It gives balanced output while doesn't break the bank like kaei tap 1.

 

[RikudouGoku]

Does tap2 have noise when in use? (during charging and not charging)

https://www.head-fi.org/threads/portable-tube-amp-from-china.626237/page-59#post-17482705

 

[DBaldock9]

Thanks for your amazing detailed explanation, I'm very grateful and impressed.
So between b4 x and tap2:
1. B4 X I manage to speak to the shop and they can modify it where it can be used while charging at the same time. The only concern is noise. Does tap2 have noise when in use? (during charging and not charging)
2. I'm able to find USB to12.6V charging cable. That solves the portable issue too.

So base on these info, any other things that may separate the two? Such as more power, better tube sound, better layering/soundstage?

I can see both device can be opened and change Op amp.

For #1 - @RikudouGoku answered that in his linked review.

For #2 - Do you have a link to the USB to 12.6V cable that has Lithium-Ion charging circuitry in it?

Other than that do u know anything about the adv portable tube? It gives balanced output while doesn't break the bank like kaei tap 1.

I've probably seen AliExpress pages for the other small tube hybrid amp - but I haven't heard one.

I have 3 tube hybrid amps - 1 desktop (Loxjie P20), and 2 portables (Little Bear B4-X, and KAEI TAP-1S) - all of which I have modified, mechanically and electronically.

 

[Thomastb]

picked up this new balanced tube unit and just wanted to drop a few early impressions; i guess it's called GAD ADV?

-very briefly tested balanced mode with hm1000 and r70x to ensure it works. then left to run for a little while.
-gets extremely hot in balanced mode. i couldn't lift it with hands until turning it off and letting it cool down. it's pretty much impossible to stack it when it's running balanced. later i will try attaching a small cooling fan made to cool down phones while gaming that i've been using to cool down my dsds ak4499.
-only one tube is used/lit up in single-ended mode
-there are two swappable op amps in place, not one as per the description. makes sense there needs to be two since it's a balanced unit. replaced cheap stock lme op amps with oracle ii (not pictured).
-it's relatively easy to access the board and op amps but the battery is attached right on top with thick double side tape pieces. i was able to carefully peal off the battery with sticking a small blade between the tape and the battery; then "attached" it back on top after op amp replacement.
-i wanted to attach silicone rings onto the tubes as well but they're very well mounted already and there wasn't space to do that.
-it's very strong. there are no gain levels so the target is clearly low sensitivity and high impedance headphones.
-my first proper sessions was with creative sxfi dongle and creative aurvana live se headphones in single-ended mode.
-creative dongle was used as dac/pre-amp. not having full line in allowed to me have some proper play on the volume knob for cal se which are not hard to drive.
-i like using this combo+headphones combo on its own and know it's signature pretty well so i wanted to see how adding gad adv in the middle would impact things.
-with double-amping or what not, the sound was still very clear and large. very low perceived noise.
-creative dongle has sxfi dsp mode that sounds like far field + subbass boost to me. this processing meant for gaming makes the staging very impactful and holographic. it doesn't work well with most headphones but cal se are tuned for this dsp. with gad adv in the mix and dsp turned on i was shocked how low distortion was. it could go very loud with powerful slam and note weight without cracking or coarseness.
-for a portable tube amp to be able to handle dsp so well is remarkable.

Hi, amazing review from you as I am also considering this amp. May I ask:
1. regarding the heat, I have read review saying its really hot, does it pass the heat to the cable and potentially damaging the cable/iem?
2. this product uses china made tube, i was wondering if there is difference to product that uses USA tube such as B4-X or tap2, is it worth to swap it to other tubes?
3. I know there are 3 modes in ADV, 1) single 2) single parallel 3) balanced. May I ask whats the difference between 1 and 2, 2 and 3

other than that, i am having a headache to utilize the balance input/output. Seems i need a pre-amp DAC with 4.4 output in order to fully utilize ADV balance tube mode

For #1 - @RikudouGoku answered that in his linked review.

For #2 - Do you have a link to the USB to 12.6V cable that has Lithium-Ion charging circuitry in it?



I've probably seen AliExpress pages for the other small tube hybrid amp - but I haven't heard one.

I have 3 tube hybrid amps - 1 desktop (Loxjie P20), and 2 portables (Little Bear B4-X, and KAEI TAP-1S) - all of which I have modified, mechanically and electronically.

just some generic cables that have USB on one sided and 12.6V on the other side. would it work well on the B4-X?

I have a few questions regarding modification of tube amp:

1. is it possible to switch tube amp by myself? I have limited to none knowledge in electric board. I know that some sort of welding is required and its not a simple plug and play like op amp
2. is it possible to switch battery from the lithium battery to typical AAA batteries (re-welding is needed I guess)

3. looks like ADV only have one tube switched on when in single mode, i wonder why B4 X and tap2 needed 2 tube in the first place as they are both using single ended instead of balanced connection
4. what other modification you have done mechanically and electronically to make the sound better.
5. BX 4 is currently using JAN 5744 (triode?), how does this compare to 5784, 5899 (pentode?)
6. ADV is using triode tube, how does it different to pentode?

Thanks for both of your kind help as I dont have much electricity knowledge.

 

[bcschmerker4]

Hi, amazing review from you as I am also considering this amp. May I ask:
1. regarding the heat, I have read review saying its really hot, does it pass the heat to the cable and potentially damaging the cable/iem?
2. this product uses china made tube, i was wondering if there is difference to product that uses USA tube such as B4-X or tap2, is it worth to swap it to other tubes?
3. I know there are 3 modes in ADV, 1) single 2) single parallel 3) balanced. May I ask whats the difference between 1 and 2, 2 and 3

other than that, i am having a headache to utilize the balance input/output. Seems i need a pre-amp DAC with 4.4 output in order to fully utilize ADV balance tube mode

just some generic cables that have USB on one sided and 12.6V on the other side. would it work well on the B4-X?

I have a few questions regarding modification of tube amp:

1. is it possible to switch tube amp by myself? I have limited to none knowledge in electric board. I know that some sort of welding is required and its not a simple plug and play like op amp
2. is it possible to switch battery from the lithium battery to typical AAA batteries (re-welding is needed I guess)

3. looks like ADV only have one tube switched on when in single mode, i wonder why B4 X and tap2 needed 2 tube in the first place as they are both using single ended instead of balanced connection
4. what other modification you have done mechanically and electronically to make the sound better.
5. BX 4 is currently using JAN 5744 (triode?), how does this compare to 5784, 5899 (pentode?)
6. ADV is using triode tube, how does it different to pentode?

Thanks for both of your kind help as I dont have much electricity knowledge.

Welding? Soldering, actually. Triodes and pentodes require different support, therefore are incompatible. Nickel-cadmium and nickel-metal hydride cells are 1.2 VDC, whereas carbon-zinc, alkaline, and lithium cells are 1.5 VDC, excepting rechargeable lithium-ion cells which are 3.7 VDC.

 

[povidlo]

Hi, amazing review from you as I am also considering this amp. May I ask:
1. regarding the heat, I have read review saying its really hot, does it pass the heat to the cable and potentially damaging the cable/iem?
2. this product uses china made tube, i was wondering if there is difference to product that uses USA tube such as B4-X or tap2, is it worth to swap it to other tubes?
3. I know there are 3 modes in ADV, 1) single 2) single parallel 3) balanced. May I ask whats the difference between 1 and 2, 2 and 3

other than that, i am having a headache to utilize the balance input/output. Seems i need a pre-amp DAC with 4.4 output in order to fully utilize ADV balance tube mode

1) No.

2) Generally, different tubes could impact the sound signature and quality. I don't think tubes are swappable in ADV. You could check with aliexpress sellers.

3) I've only tried '1' and '3'.
'1' is single-ended class A 3.5 output on single-ended 3.5 input.
'3' is balanced 4.4 output on 4.4 balanced input.
Seems like '2' is either 3.5 real balanced like old school balanced hifiman or fake balanced like ifi s-balanced. Will message the seller when I have a moment.
I haven't had the need to use '2' since '1' is very powerful already. It drove lcd-2 with no issues with barely going above just 9-10 o'clock on the knob.

4) To use balanced 4,4 output, you need to connect to 4.4 balanced input. I've been using hm1k and gryphon as balanced sources, they have 4.4 balanced out. Otherwise it will take any other balanced input, like from 2.5 or from 2xXLR, you just need a proper cable/converter to connect to ADV's 4.4.

After spending a little bit more with it, I can report that ADV is an extremely powerful portable tube amp and a little bit noisy as well. Definitely not appropriate for sensitive ear/headphones. There's are no gain levels and there is significant channel imbalance up to about 8 o'clock knob mark.

Right now I also own b4-x and korg ha-s with nutube in terms of portable tube amps. Korg is the most refined and cleanest sounding one out of the three and it has been getting the most airtime.

 

[Thomastb]

1) No.

2) Generally, different tubes could impact the sound signature and quality. I don't think tubes are swappable in ADV. You could check with aliexpress sellers.

3) I've only tried '1' and '3'.
'1' is single-ended class A 3.5 output on single-ended 3.5 input.
'3' is balanced 4.4 output on 4.4 balanced input.
Seems like '2' is either 3.5 real balanced like old school balanced hifiman or fake balanced like ifi s-balanced. Will message the seller when I have a moment.
I haven't had the need to use '2' since '1' is very powerful already. It drove lcd-2 with no issues with barely going above just 9-10 o'clock on the knob.

4) To use balanced 4,4 output, you need to connect to 4.4 balanced input. I've been using hm1k and gryphon as balanced sources, they have 4.4 balanced out. Otherwise it will take any other balanced input, like from 2.5 or from 2xXLR, you just need a proper cable/converter to connect to ADV's 4.4.

After spending a little bit more with it, I can report that ADV is an extremely powerful portable tube amp and a little bit noisy as well. Definitely not appropriate for sensitive ear/headphones. There's are no gain levels and there is significant channel imbalance up to about 8 o'clock knob mark.

Right now I also own b4-x and korg ha-s with nutube in terms of portable tube amps. Korg is the most refined and cleanest sounding one out of the three and it has been getting the most airtime.

Thanks for your explanation, korg looks interesting but is however 4 times the price of ADV. Does balanced output in ADV gives less noise?

 

[Thomastb]

1) No.

2) Generally, different tubes could impact the sound signature and quality. I don't think tubes are swappable in ADV. You could check with aliexpress sellers.

3) I've only tried '1' and '3'.
'1' is single-ended class A 3.5 output on single-ended 3.5 input.
'3' is balanced 4.4 output on 4.4 balanced input.
Seems like '2' is either 3.5 real balanced like old school balanced hifiman or fake balanced like ifi s-balanced. Will message the seller when I have a moment.
I haven't had the need to use '2' since '1' is very powerful already. It drove lcd-2 with no issues with barely going above just 9-10 o'clock on the knob.

4) To use balanced 4,4 output, you need to connect to 4.4 balanced input. I've been using hm1k and gryphon as balanced sources, they have 4.4 balanced out. Otherwise it will take any other balanced input, like from 2.5 or from 2xXLR, you just need a proper cable/converter to connect to ADV's 4.4.

After spending a little bit more with it, I can report that ADV is an extremely powerful portable tube amp and a little bit noisy as well. Definitely not appropriate for sensitive ear/headphones. There's are no gain levels and there is significant channel imbalance up to about 8 o'clock knob mark.

Right now I also own b4-x and korg ha-s with nutube in terms of portable tube amps. Korg is the most refined and cleanest sounding one out of the three and it has been getting the most airtime.

Also, what opamp did u modified for the little bear? If u have to choose between little bear VS ADV, how would that be? It would be kind of u to describe whats the pros and cons for all three too. Thanks a million

 

[VeightTripleDivision]

I am also owner of ADV amp, it has less noise than my DIY prototype, which has DC-DC converter at 150VDC.

There are three modes, one is for normal SE 3.5mm operation, with one tube working. Then there is parallel mode for 3.5 SE with both tubes (and most likely also output stages) paralleled.
Third mode is for balanced connection.

LM4562 opamps were not original inside (different bias currents and offset voltages). So far it's the only thing I've changed. Would like to do more, but space is limited, I do not see how this device can have "real" class A output stage - SOT23 could not dissipate much heat.

But as I said, it does better than my DIY portable hybrid, so I am gonna use it as is for a while before attempting any mods that might break it.

 

[Ayretan]

Today Burson sent me some of their V6 Vivid Op amps for my little bear tube amp. At first listen I am floored by the difference but hope as they burn in that the high end settles down a little. Made my xenns tea a little too bright for my taste lol..

 

[Ben86]

1) No.

2) Generally, different tubes could impact the sound signature and quality. I don't think tubes are swappable in ADV. You could check with aliexpress sellers.

3) I've only tried '1' and '3'.
'1' is single-ended class A 3.5 output on single-ended 3.5 input.
'3' is balanced 4.4 output on 4.4 balanced input.
Seems like '2' is either 3.5 real balanced like old school balanced hifiman or fake balanced like ifi s-balanced. Will message the seller when I have a moment.
I haven't had the need to use '2' since '1' is very powerful already. It drove lcd-2 with no issues with barely going above just 9-10 o'clock on the knob.

4) To use balanced 4,4 output, you need to connect to 4.4 balanced input. I've been using hm1k and gryphon as balanced sources, they have 4.4 balanced out. Otherwise it will take any other balanced input, like from 2.5 or from 2xXLR, you just need a proper cable/converter to connect to ADV's 4.4.

After spending a little bit more with it, I can report that ADV is an extremely powerful portable tube amp and a little bit noisy as well. Definitely not appropriate for sensitive ear/headphones. There's are no gain levels and there is significant channel imbalance up to about 8 o'clock knob mark.

Right now I also own b4-x and korg ha-s with nutube in terms of portable tube amps. Korg is the most refined and cleanest sounding one out of the three and it has been getting the most airtime.

Does op-amp swap affect overall sound quality in ADV? I see from your photo that you have Burson opamps? Does these apamps affect quality of overall sound and how much is that effect heard? I'm confused which one of these portable amps to choose I use only my full-size headphones: HD650, Focal Clear, Audeze-X.

 

[povidlo]

Does op-amp swap affect overall sound quality in ADV? I see from your photo that you have Burson opamps? Does these apamps affect quality of overall sound and how much is that effect heard? I'm confused which one of these portable amps to choose I use only my full-size headphones: HD650, Focal Clear, Audeze-X.

Op amps on ADV are not swappable. Photo shows bursons with little bear B4X, in which case they significantly improve dynamics and staging. For full size cans, i'd rec ADV it's very powerful.

 

[Ben86]

Op amps on ADV are not swappable. Photo shows bursons with little bear B4X, in which case they significantly improve dynamics and staging. For full size cans, i'd rec ADV it's very powerful.

But as I see from the photo ADV has two DIP8 sockets to swap op-amps

 

[povidlo]

But as I see from the photo ADV has two DIP8 sockets to swap op-amps

Marketing photo? Good luck accessing those sockets. I could not.