[elvispreasley]

That's quite a stack.
What are the advantages of this system compared to using a small dnla capable DAP such as the Hiby R2?

The short answer is - a lot.
To be more specific. I don't have an experience with R2, but used R3 as a transport before I moved on to Beaglebone and it far less convinient. First of all, R3 can't play some of the albums from Tidal. Not a lot, but the fact is still remains. Second, R3 can't play gappless with Tidal, which is pretty annoying, especially when you're listening 100+ tracks album of the trance music, where all songs creating one long composition. Third, it's tricky to navigate through your music library with such a small screen. Fourth, R3 has no MyMixes in its Tidal.
The beaglebone itself is absolutely outstanding transport even with stationary setup, so in portable it's simply unbeatable. With simple and light weight custom OS (Linux based) it shows only streaming protocols to chose from (check the attached screenshot) and can be used as an end point for Roon, streaming your local music library from Audirvana through UpNP and the most important for me - playing the music through the Tidal Connect, which streams directly from the Tidal web servers, avoiding all of the software players, codecs and everything else, which may affect SQ, despite of the bitperfect. Also the official Tidal app might be used for navigation, which is super convenient and gives you the maximum available features.

 

[Bosk]

Perhaps I'm just imagining things, but I seemed to have noticed an improvement by wrapping my Burson V6 Vivids in copper tape to shield them.

 

[Bosk]

Quick question guys - does the grounding point next to the volume pot connect to the chassis through the pot's shaft?

It kind of looks like it does but I just want to confirm. If it does I tend to wonder how electrically effective that connection is and if it shouldn't be enhanced....

 

[DBaldock9]

The wire from the GND point does connect the circuit board to the front panel, if the nut is tight on the Volume Control shaft.
.
When I was adding the capacitors to the bottom of the board, I went ahead and added an additional copper GND wire around the shaft.

 

[Bosk]

I finally finished working on my modded B4-X.

All the resistors in the signal path are now Z-foils, the signal path wiring I replaced with pure silver litz (pain to work with), and DIYed a sort of cover to protect the op-amps & caps poking through the top of the case. I also shielded most of the components with copper tape.... not sure that did much for performance, may have had a small effect with the Burson v6s, but looks cool.

Sonically the background isn't dead quiet (I have no idea how to get this amp completely silent) and there's still the occasional very faint crackling noise, but actual performance is nothing short of superb with great dynamics, soundstage (though that's probably still a weak point vs big desktop amps), gobs of detail & musicality, everything sounds very congealed & direct. Probably being held back by my relatively inexpensive IEMs I suspect.

Here's my other B4-X which I'm keeping in a true portable form factor.

Still working on this one, essentially its the same mods as the other B4-X except the battery isn't being replaced, the op-amps are Burson V5is instead V6s, and the Silmic IIs are a lot smaller. Performance is understandably nowhere near as good, as even the battery alone makes a big difference. Still working on it hope of getting it as close to its' big brother as possible.

 

[Makswell]

I finally finished working on my modded B4-X.

All the resistors in the signal path are now Z-foils, the signal path wiring I replaced with pure silver litz (pain to work with), and DIYed a sort of cover to protect the op-amps & caps poking through the top of the case. I also shielded most of the components with copper tape.... not sure that did much for performance, may have had a small effect with the Burson v6s, but looks cool.

Sonically the background isn't dead quiet (I have no idea how to get this amp completely silent) and there's still the occasional very faint crackling noise, but actual performance is nothing short of superb with great dynamics, soundstage (though that's probably still a weak point vs big desktop amps), gobs of detail & musicality, everything sounds very congealed & direct. Probably being held back by my relatively inexpensive IEMs I suspect.









Here's my other B4-X which I'm keeping in a true portable form factor.

Still working on this one, essentially its the same mods as the other B4-X except the battery isn't being replaced, the op-amps are Burson V5is instead V6s, and the Silmic IIs are a lot smaller. Performance is understandably nowhere near as good, as even the battery alone makes a big difference. Still working on it hope of getting it as close to its' big brother as possible.

Your work is incredible! Looks like a factory product. I wanted to ask. Could you list all the changes made to the device in full? Have you tried to put Burson v6s into the case using an adapter - https: //www.bursonaudio.com/product/35mm-extension-lead-x-2/ , if you remove the plastic case, there should be a place for them. Or maybe you tried to put the capacitors sideways, trying to fit them inside the case?

 

[Bosk]

Your work is incredible! Looks like a factory product. I wanted to ask. Could you list all the changes made to the device in full? Have you tried to put Burson v6s into the case using an adapter - https: //www.bursonaudio.com/product/35mm-extension-lead-x-2/ , if you remove the plastic case, there should be a place for them. Or maybe you tried to put the capacitors sideways, trying to fit them inside the case?

Thanks Makswell.

No I haven't tried fitting the V6s in the space made vacant by removing the old battery, it would be a pretty tight squeeze though and allow no leftover room for larger caps. The Silmic IIs I used definately won't fit in that space lying down but obviously smaller caps could be used instead.

From memory I performed the following mods:

Replaced op-amps with Burson V6s
Added two Wima 0.1uF film caps to each op-amp on pins 1 & 5, other end to ground
Cut signal path PCB traces, replaced them with pure silver litz wire
Replaced all audio section solder joints with Oyaide SS-47
Replaced all resistors with Vishay Z-foils & Takman Carbon films
Replaced Volume pot with two fixed Z-foil 15k resistors
Replaced 1,000 mAh stock battery with 10,000 mAh battery
Replaced electrolytics with Silmic IIs, 4x 470uF 63v & 1x 470uF 100v for the largest stock electrolytic
Created new PCB for electrolytics & connected them to stock PCB using OCC copper wire
Created braided OCC copper wire power cable
Shielded most components & stock metal case roof/floor with copper shielding tape
Superglued cut panels from spare B4-X case to fill top panel gap around op-amps
Sanded away anodized coating in all places where different parts of the case touch, to improve grounding
Added tube o-rings to reduce microphonics
Added EAR small isolation feet to bottom of the case
Added DIY top cover using cut plexiglass & hex standoffs to protect op-amps & caps


Here's another quick photo

 

[DBaldock9]

Thanks Makswell.

No I haven't tried fitting the V6s in the space made vacant by removing the old battery, it would be a pretty tight squeeze though and allow no leftover room for larger caps. The Silmic IIs I used definately won't fit in that space lying down but obviously smaller caps could be used instead.

From memory I performed the following mods:

Replaced op-amps with Burson V6s
Added two Wima 0.1uF film caps to each op-amp on pins 1 & 5, other end to ground
Cut signal path PCB traces, replaced them with pure silver litz wire
Replaced all audio section solder joints with Oyaide SS-47
Replaced all resistors with Vishay Z-foils & Takman Carbon films
Replaced Volume pot with two fixed Z-foil 15k resistors
Replaced 1,000 mAh stock battery with 10,000 mAh battery
Replaced electrolytics with Silmic IIs, 4x 470uF 63v & 1x 470uF 100v for the largest stock electrolytic
Created new PCB for electrolytics & connected them to stock PCB using OCC copper wire
Created braided OCC copper wire power cable
Shielded most components & stock metal case roof/floor with copper shielding tape
Superglued cut panels from spare B4-X case to fill top panel gap around op-amps
Sanded away anodized coating in all places where different parts of the case touch, to improve grounding
Added tube o-rings to reduce microphonics
Added EAR small isolation feet to bottom of the case
Added DIY top cover using cut plexiglass & hex standoffs to protect op-amps & caps


Here's another quick photo

Just wondering - with the capacitors connected between the op-amp outputs and GND - doesn't that just roll off the high frequency signals? Were you having issues with oscillations?

 

[Bosk]

Just wondering - with the capacitors connected between the op-amp outputs and GND - doesn't that just roll off the high frequency signals? Were you having issues with oscillations?

Perhaps I mentioned the wrong pins, I followed this guide.

https://www.bursonaudio.com/burson-ss-opamp-101-part-1-mkp-cap-tweak/

 

[elvispreasley]

Moved forward from B4-x to more advanced portable tube amps and build 2 portable setups with Alo Continental V5 and Phatlab Sassy GT. Well, this is absolutely another story, I must admit. Especially with Sassy GT, which is soundind way better then my stationary hybrid tube amp.

 

[Bosk]

Yesterday I replaced the last of the signal path traces with silver litz wire in both my B4-Xs.

I'd been putting this off because following the exact signal path as it leaves the 27R resistors is difficult. The traces start on one side of the board and finish on the other, the PCB lettering at the 2.5mm jack area is smeared so I couldn't tell which was the L+ contact, and the signal gets fed through the relay before reaching the jack. Anyway it worked, below is the correct path if anyone else wants to perform this mod. I soldered the wires on the resistor end directly to the visible portion of the 27R lead on the top side of the board, same side as the 2.5mm jack which is surface mount not through hole.

Sonically this change has been tremendous. Imaging is more stable, everything feels more relaxed yet detail levels are the same or better, and surprisingly there's even less background noise/crackle than before. Originally I was very surprised how much improvement came from replacing signal path traces with silver wire and had I performed all sections at once the difference would've been even more obvious. Considering how cheap 1m of pure silver wire is these days its possibly even better value than replacing the power supply caps, but a lot more work.

Overall my "big brother" B4-X is performing at an extremely high level now. It sounds like a very high-quality desktop amp and I tend to wonder how many off-the-shelf amps out there with a similar form factor would be capable of matching its' performance.

 

[Muniek66]

Hi guys,

will you recommend a cheap, compact Chinese tube amplifier (to work with the FiiO BTA30), to which I can connect both headphones and active speakers?

I was thinking about the following:

https://aliexpress.com/item/32675687955.html?spm=a2g0s.8937460.0.0.663d2e0eZ24DVU

https://aliexpress.com/item/32896796924.html?spm=a2g0s.8937460.0.0.663d2e0eZ24DVU

Or a bit more expensive:

https://aliexpress.com/item/1005002005882893.html?spm=a2g0s.8937460.0.0.1c302e0epDk0d6

Thanks in advance for your help.

 

[Setmagic]

I would like to share with You with my last foundling. Zishan is famous from good cheap portable DAPs. He create also super compact and ultra cheap tube amplifier AD3.

Device is not a perfect from factor but with little attention can be really impressive.



- Removed blocking output caps (big improvement)
- USB-C port with fast charging
- OPAMP replaced to OPA1612

 

[Setmagic]

@edit
- changed soldering to tin-silver+pb Cardas
- replaced cheap potentiometer for paired metal DALEs resistors 0,5W <1% 14kom working in fixed 1/3 nominal gain
- caps replaced for Nichicon Fine Gold dual 100nF 25V (200nF) in analog power rail and additional small 1x 100nF + 2x22n 50V (144nF) Nichicon FW(m) Audio grade for Tube supply.


@edit
10kom works way better than 14K as resistor.

 

[Setmagic]

Grade of quality and amount of uF in rail.
Most differences causes change this white caps on the top (left corner) to red WIMA 5% and capacity(right side) for Tube supply.
2 x220uF 63V paired with stock 100nF V50
Stock Capacitors Vs Nichicon Fine Gold.
Muses was for opamp supply just in case but do not give any improvements.


Final project ready to close in case.
Nichicon Fine Gold 50V 147uF (100+47)