Tubing IEMs for mobile use

I’m getting the Little Bear B4-X (per Z’s recommendation of course) and I’m planning to use it mobile. I currently have Tin T2’s and Fiio FH5’s for mobile use, getting the Tin P1’s when they ship this week as well. I don’t how how any of them will react to being tubed, I’ve heard that planars don’t respond well to tubes. Was wondering if anyone has experience they are willing to share about tubing the T2’s or balanced armatures like the FH5 has. Looking to start a conversation about people’s experience tubing IEMs (with an emphasis on mobile use)


I have no experience with this, but I think it will be nice to learn about! Keep us/me informed, you might start a tubular revolution :wink:

Tubes can be effected by devices that transfer signals like mobiles and routers etc, so it will be interesting to see how otg works out :+1:

So the thing with Planars is they are low impedance. Tube amps are usually good for high impedance gear. Hence why the HD600 work well on a good tube. IEM’s in general are low impedance.
The problem is potential noise. You usually want your output impedance of your amp to be 1/8th the impedance of your headphone/earphone.
So there is potential for noise to be heard on a low impedance IEM

The other reason Planars usually don’t do so well on tubes (or at least the sentiment that they don’t) is the power requirement. Planars sometimes peak at needing quite a bit of power. Most tube amps can’t provide say 1 watt.
This is obviously not a problem for efficient planars though.

Good luck and let us know how it goes.

Is the Little Bear a hybrid tube amp? Not very familiar with the model. If it is a hybrid then one should be alright to use with an IEM since the power of the amp isn’t being ran through a tube. Just speculation of course, and I don’t have any experience AB testing with a hybrid vs true tube using IEMs that are as sensitive as the P1s.

it it a hybrid design and it states it is recommended to use devices with an impedance of 16-300ohm. But that can mean nothing sometimes too.

Could not find any mention of the output impedance. Seeing as it is hybrid. It should be okay. But until you try it you won’t know.

The P1’s are 20 ohm and very revealing. So you should know very quickly if there is a problem.

A lot of tube headphone amps have gain and dip switches like the little Dot MkIIA.
Switch 1 off, Switch 2 off = Gain 10 (Highest Impedance)
B. Switch 1 on, Switch 2 off = Gain 7 (Medium Impedance)
C. Switch 1 off, Switch 2 on = Gain 5 (Low Impedance)
D. Switch 1 on, Switch 2 on = Gain 3 (Lowest Impedance)

So you can tune your own impedance even more so than direct/iem output plug/switch :+1:

I think this particular tube amp is just an amp so it has a 3.5 mm input, not usb

USB has nothing to do with dip switch controls or gain.

Digital vs analogue. This is an amp and therefore analogue. Gain switches are analogue and gain in general is analogue except when you are digitally adding gain which is in general very bad and nobody should do it.

However yes the specific Little Bear P4X does not have gain switches. Not everything does since it adds cost and complexity. This is a very cut down product already.

The B4-X does advertise on Amazon as suggesting 16 to 300 ohm loads, so it may work.

I wouldn’t recommend the B4X for mobile use, there is a lot of noise interference if you have it within 50cm of your phone. Look at the Oriolus BA300S, its just better in every way and won’t become horrendously noisy when your phone isn’t on airplane mode.

mmmmm. Not really. But I see where you are coming from.

Build quality absolutely yes.
But if you were considering op amp rolling then the BA300S does not offer that.
The Little bear is also about 100mw more powerful. So the Oriolus loses there.
Lets not forget about the price being 4X as much for the Oriolus.

So “it’s better in every way” is not quite accurate.
“It is better in some areas”, would be more fitting.

The noise on the Little bear can be fixed. So not too much of a problem.
All you need is some thick aluminum backed tape, some kapton tape plus a bit of time.

You open the whole unit up. cover the inside surfaces with the aluminum tape and then kapton to act as a temperature safe non conductive barrier.
Problem solved for something like 10 usd plus leftovers for another project.

At the end of the day if you can afford to spend 400 usd on a portable balanced tube amp and you don’t feel like you will miss the money then that is fine.
If you do feel like you will miss the money or it is too much then the Little bear exists.
And I am sure over time they will fix the issue. Most likely they haven’t quite grounded to the case correctly or it could be due to the placement of the window being so close to the tubes and thereby allowing them to pick up signals.
The tubes they used could also be sensitive to interference.

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