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FX Audio TUBE-03MKII BT Tube Preamp & Headphone Amp
01 / 08
FX Audio TUBE-03MKII BT Tube Preamp & Headphone Amp
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167 requests
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232 Sold
Product Description
Between your audio player and your headphones, several pieces of equipment can improve your sound. If you’re looking for signature tube warmth, you can get them all in one device: the TUBE-03MKII from FX Audio Read More
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mattris
1300
Jun 3, 2022
thmsIn the description: "The onboard headphone op-amp (OPA1656IDR) can also be replaced by higher-end op-amps like the MUSE02 or AD827."
SuperFlyEDSguy
62
Jun 6, 2022
thmsGreat question!
The dual replaceable Op-Amps are used to provide additive graphic equalization for the bass and treble controls via their pots (Rf) being in their respective feedback loops. The included Op-Amps are okay, are not really used for “coloring” audio, and will likely add a maximum 14dB to 15.5dB of bass or treble. It’s actually kind of a neat way to achieve equalization! You could of course add premium Op-Amps to help “color” the audio. To me, Burson V6 Classic Discrete Op-Amps would seem the natural choice. The Burson V5 would be more of a value specific choice, but you can’t go wrong with Burson (just NOT the V5i as you won’t find the overall value with them!!!) Just check the datasheets to ensure that you won’t go over the maximum current draw!!!
Note that two Dual Op-Amps are used. Each Channel (Left & Right) will require a separate Dual Op-Amp as the Bass frequencies are needed for one and the Treble for the other. The frequencies are then recombined before going to their respective Left or Right tube. This is why Dual Op-Amps are required (or four total ‘amplification’ paths), but only one tube is needed per channel.
The tubes, I can assure you, are most definitely real, though do yourself a favor and get yourself a closely matched-pair of NOS GE 5654W from Riverstone Audio! These tubes do color the sound, but don’t add amplification as that would call for about a minimum of 10x the voltage as per the datasheet. You will still get the “coloring” regardless as even a very small current being present will offer it. I have the first revision of this device along with the Riverstone tubes followed-up with an O2 Amp, and it sounds great!
Let’s not forget that this is ideally a solid preamp as preamps are not designed to amplify other than to (1) bring voltage to line-level when necessary or to (2) “color” sound, which may require a bit of amplification as a means to an end. Otherwise, preamps by definition could be used to (3) select audio-pathways (ins/outs) for amplification at a later stage. By looking at the board, the power circuit looks decent enough, the 5-band (blue) resistors are high quality, excellent caps are used to avoid noise at the beginning and final stages. The ultimate test is how it sounds though, and with the addition of the above tubes that cost me maybe $25, it sounds pretty damn good!
Good luck and be well!
——
Edits:
1) Fixed typo.
2) Added note on Dual Op-Amps.
(Edited)
Constant_Staff
9
Mar 13, 2022
just bought 2 of these (one for my computer desktop setup and one for my stereo system), I was curious if anyone can give me a full list of the tubes that are compatible with this device since it is my first foray into tubes, and thus would like to do the tube rolling with it, and if you can specify how each of the different tubes will effect the sound such as if it will make it clearer, warmer, darker, or more metallic etc... does the voltage have to match when tube rolling?
(Edited)
SuperFlyEDSguy
62
Jun 6, 2022
Constant_StaffTake a look at the following link, specifically section 3 as it goes into a good amount of detail and should answer your questions:
https://www.head-fi.org/threads/little-dot-tube-amps-vacuum-tube-rolling-guide.563884/
BlooKazoo
379
Jun 1, 2022
D21esI wonder this too, just looks like some garbage off amazon or aliexp. Can't believe drop is selling this.
Rowdy2026
805
Jun 2, 2022
BlooKazooWhat’s even more baffling is people claiming they can ‘tube roll’ with positive effects on this underpowered solid state amp…not to mention the power supply couldn’t actually keep a candle burning.
AJCxZ0
2
Mar 9, 2022
RonChenIt is a very different kind of device. This is a tube pre-amp which only has a DAC for the Bluetooth.
The MT602 is a headphone DAC and amp with a tube pre-amp stage built in.
[Thanks to @BlooKazoo for the correction.]
(Edited)
BlooKazoo
379
Jun 1, 2022
AJCxZ0What? The mt602 (as it exists on drops site) has no built in dac, it is purely a pre/amp.
mpearce
1
Jan 7, 2021
Just received mine, no RCA cable, no Bluetooth antenna and wrong tubes, what a joke.
kkkcok
3
Jan 6, 2021
Just received today one month delayed. It came with 6K4 tubes instead of the GE5654 tubes and no RCA cable.
SuperFlyEDSguy
62
Jun 6, 2022
kkkcok6K4 tubes are basically ‘generic’ GE5654 tubes, did the description say that they’re including the OEM GE tubes? Either way, it’s the GE 5654W tubes that you really want as they’re military grade, originally designed for and used on military radar systems, and sound exponentially better!
UndoneChopSuey
2
Dec 22, 2020
VanHaiLooks like everyone got the wrong tubes and no RCA cable.
I was so disappointed about the wrong tubes and didn't realize the RCA cable was missing.
Anyway, Drop did offer a partial refund to cover the GE tubes when I contacted them.
UndoneChopSuey
2
Dec 15, 2020
Just received mine and it came with 6K4 tubes instead of the GE5654 tubes...
Cyberthingy
289
Dec 18, 2020
UndoneChopSueySame Here... Rather disappointing since that was the reason I chose to give this preamp a shot. Maybe that was the reason for the delayed shipment. They ran out of GE and had to secure a substitute?
kata2012
9
Dec 18, 2020
UndoneChopSueySame thing here. received the 6K4 tubes and I'm pretty disappointed about it as the GE tubes were one of the main reasons I was picking up this particular unit.
Edc-lurker
5
Dec 2, 2020
Glad you all received yours; I have been waiting months! Excited about getting it. Trying to run my senheriser px38 (sp?) and they claim they delivered it already... ugh
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