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REVIEW: Firestone Audio Amps - Cute Beyond and Fubar III

post #1 of 56
Thread Starter 
About 3-4 weeks ago I received the Firestone Audio "Cute Beyond" and the "Fubar III" product samples to review, courtesy of head-fi user miziq and Welcome to Miniature Audio -Firestone Audio -USB DACS -Headphone Amps - but I didn't have time to start reviewing them until last week.

These are small desktop amps that run on 24v power, I am assuming with the goal to provide better voltage swing than those ubiquitous portable units, without using up much more desktop space than the portable units. One of the things that you'll notice is that they bear a strong resemblance to the Travagans amplifiers that I reviewed previously, thanks to amp designer David Lin who was formerly with Firestone Audio.

The "Cute Beyond" would be the counterpart to the "Travagans Red" amp, taking analog RCA inputs to feed the amplifier. The "Fubar III" would be the sibling to the counterpart to the "Travagans Green".

However, size and shape and trademark looking volume knob are about where the similarities end. Where the Red lacks the hi/lo gain switch on the back, it adds 5 watts/channel worth of banana jacks for speakers. And where the Green lacks the 2 position gain switch and analog outputs on the back, it adds the same 5 watts/channel of banana jacks for speakers PLUS a coax and optical digital out (the Green's only analog out is the headphone jack in front). The Firestone Audio products also include an on off switch on the back, while the Travagans incorporate the power on into the volume knob. All have 1/8" headphone out and volume control in the front.

HEADPHONES: I used 4 headphones for the review - Ultrasone Edition 9 with APS V3 cable, as well as a Grado RS-1 and HD600 with the same kind of cable, plus my Livewires extremely sensitive/low impedance custom in ear monitors.

SOURCE: Headroom 2006 Micro DAC with iRiver H140 and Macbook optical out, and Macbook for USB DAC testing. Red Wine Audio iMod with V-Cap dock and lossless files.

MUSIC: Diana Krall "Girl in the Other Room", Jack Johnson "Sleep through the Static", Tsuyoshi Yamamoto "Autumn in Seattle" and "Smooth Jazz Festival", K2 "This is K2 HD Sound", Guinea Pig "Kool Cats", Herbie Hancock "River: The Joni Letters", Jazz at the Pawnshop, Karunesh "Call of the Mystic".

CUTE BEYOND: Price: $187.00





Features: The Cute Beyond has the power switch and 2 position gain switch on the rear, along with the 24v DC input and a pair of RCA jack audio inputs. On the front is the power-on light, 1/8" headphone jack and volume control.

* Volume control internal switch for Series or Shunt (adjust to suit your taste)
* OP amplifiers exchangeable! You can tune the sound if needed
* 100 - 240Vac 50/60 Hz external auto-switching power supply included
* External gain switch make it easy to match low or high impedance headphones
* Short circuit and thermal protection

It is optimized for a wide range of load impedances from the Etymotic ER4P (27 ohm) to the AKG K240DF (600 ohm). This high bandwidth, extreme low noise design (lower than -107db) yields greater than 105 dB of dynamic range.

Cute Beyond Headphone Amp Specifications

* Circuit Design: OPA2227 for main amplifier, current boosters NPN/PNP power transistors
* Class: Class A amplifier
* Output Resistance: Extra low output resistance (Zo - 0.05 ohms),high current capacity
* Frequency Response: 6Hz~300Khz ,-1dB at 100 ohms loading, very low noise
* Max. output: 6Vrms (with 24 VDC Power Supply)
* Headphone Impedance: 8 - 600 Ohms (See headphone matching chart for additional information)
* Size: Size: 11cm/4.3in(L) x 8cm/3.2in(W) x 5cm/2.0in(H)
* Weight: 500g / 17.6oz

IMPRESSIONS:

Feeding the Cute Beyond from my Headroom Micro DAC with lossless files through the optical input, I was pleasantly surprised the first time I jacked in my Edition 9 and hit the play button. What I heard was dynamic and clean, quick and responsive, and detailed with ambience and musicality. Timbre seems rich and accurate, and portrayed instruments the way I expected them. The upper treble and deep bass seemed to be present and accounted for as well.

However, the soundstage was presented in a little more forward manner than I typically prefer, but was still quite acceptable although it put me on stage instead of in 1st or second row. I switched the headphones to the Grado RS-1, and then to the HD600 and found the sound signature and imaging to be unchanged whether I was using 30 ohm or 300 ohm headphones. This forward perspective on the musical soundstage somewhat reminded me of the Meier 2MOVE's soundstage, which I reviewed about 2 months ago - good for more intimate settings but less so with large venue classical.

The Cute Beyond also seemed to have more than enough power to drive any of my headphones while in low gain. The RS-1 and Edition 9 could be played at painful levels, had I not put in earplugs to block the noise so that I could listen for distortion at high volumes. Firestone's specs claim about 6v output at the headphone jack! With the Cute Beyond a typical volume knob position for normal listening volume levels with the RS-1 and Edition 9 was about 10 - 11 o'clock, and I don't think I could stand 1 o'clock for long. The HD600 could be played at normal listening volume levels at 1-2 o'clock in low gain, and max at 5 o'clock was very loud but still below painful. I didn't think the sound changed character with the different gain levels. If I owned this amp, I doubt I would ever turn up the gain from low to high, unless I had a source that had too low of an output volume to properly feed into the Cute.

Having several other amps in the same target price range and category on hand, I did a comparison with my Travagans Red, Meier HeadFive and Headroom 2006 Micro Amp. I did not take the time to remove the AD743 opamps from the Red and replace the stock LM4562. With extended listening, NONE of these amps are losers; and the differences are relatively small but audible with no glaring faults. All the amps drove the Edition 9 and HD600 very well, but with the RS-1 I thought the HeadFive seemed just a little thinner than with the other amps when the volume was turned up high. I found the Cute Beyond to be the most forward of the amps, followed by the Meier HeadFive. On the other hand, the Travagans Red and HR Micro Amp seemed to be less forward and a little more spacious in the soundstage, yet without ever sounding thin or distant. With the three full size headphones that I used, I liked the Travagans Red only a micro-smidgeon more than the HR Micro Amp, followed closely by the Cute Beyond and then the HeadFive (my NuForce Icon is not burned-in yet and it's HP out is not up to these levels yet). I wont give an absolute score on a scale of 10 or anything, but will say the difference between the worst and best was a matter of single digit percentage points (so the worst is at least 90% as good as the best, if not more).

I had noted that the Travagans Red had some channel imbalance at very low volume levels in my previous review. So, I checked the Cute Beyond for this issue as well, and it is there at low volumes too. At the lowest point where there is no channel imbalance, the Cute Beyond volume knob is turned to 8 0'clock, while the Travagans Red is at 9 o'clock. At these settings, both amps produced the SAME volume through the headphones, which was below my normal listening at 10-11 o'clock. I pulled out my Livewires custom molded IEM to see if the channel imbalance would interfere with normal listening in very high sensitivity IEM, and fortunately the volume was right at normal listening levels with either amp. However, to use the IEM with music at background levels, such as to fall asleep, I had to use a Shure volume attenuator to further reduce the volume without touching the volume on either amp. The Meier HeadFive and Headroom Micro Amp had NO channel imbalance at the lower volume levels, and the Shure attenuator was not needed to play very quiet with the IEM. I did not notice any problems with hiss and my high sensitivity IEM either.

One interesting thing I discovered was that the low impedance Livewires sounded best from the HR Micro Amp, and not by a small margin either - they just had great synergy there. As previously tested, the Red with Livewires and the stock LM4562 opamp was fine; but the AD743 was the winner when driving my full size dynamic and electrostatic headphones. But now the LW were sounding a little more dull from the Travagans Red with AD743, unlike with full size headphones. The LW were a little brighter but maybe too forward from the Cute.

In summary, I found the Cute Beyond to be a very capable SS mini-desktop headphone amp, and a good value for driving a wide variety of headphones. In my case, for the same price I find the Travagans Red to be a better value because of the 5 watt/channel speaker jacks, which do a fabulous job driving my Stax electrostatic headphone transformers. I would rather have the speaker jacks on the red than the gain switch that the Red lacks. And, if I wanted to use the Livewires on a regular basis with the Red, I would just put the stock LM4562 opamp (or something else) back in, which was still good with full size headphones too.

Fubar III: Price: $229.00







Features:

The Fubar III was created by combining the Fubar II USB Dac with the Cute II Headphone Amp. With no additional software or drivers needed, it is plug and play compatable with Windows, Mac and Linux. It can feed any amp or preamp via a pair of RCA outputs, and also lets you use the built in headphone amp. Its analog output uses the Burr Brown OPA2604AP opamp which is socketed, allowing you to "roll" or swap out opamps to customize the sound if needed.

It has the power switch and 2 position gain switch on the rear, along with the 24v DC input and a pair of RCA jack audio outputs. On the front is the blue power-on LED, Green LED for USB DAC active (to tell you when the computer is using the DAC, and not just if it is plugged in), 1/8" headphone jack and volume control.

The Fubar is also designed to work with most headphones from the Etymotic ER4P (27 ohm) to the AKG K240DF (600 ohm). It is a low noise design (lower than -107db) that yields greater than 105 dB of dynamic range.

Additional Features:

* Volume control internal switch for Series or Shunt (adjust to suit your taste)
* OP amplifiers exchangeable to tune the sound
* 100 - 240Vac 50/60 Hz external auto-switching power supply included
* External gain switch to match low or high impedance headphones
* Short circuit and thermal protection

Specifications - USB DAC section:

* Digital to Analog Burr Brown PCM2702 DAC, 16 Bit 44.1 KHz / 48KHz sampling rates
* OP Amplifier OPA2604 (socketed and exchangeable)
* Circuit Specifics Independent regulators for digital and analog circuits, DC amp uses no coupling capacitors.
* Frequency Response: 10Hz~25KHz ,-1dB at 600 ohms loading, low noise -99dB(A)

Specifications - Headphone Amp section:

* Class Class AB / DC amplifier, uses no coupling capacitors
* Output Resistance: Extra low output resistance (Zo - 0.05 ohms), high current capacity 800mA per channel.
* Frequency Response: 6Hz~300Khz , -1dB at 32 ohms loading, very low noise -110dB (A)
* Max. output: 6Vrms external gain control switch
* Headphone Impedance: 8 - 600 Ohms (See headphone matching chart above for additional information)
* Size: Size: 11cm/4.3in(L) x 8cm/3.2in(W) x 5cm/2.0in(H)
* Weight: Fubar III only 350g / 12.3oz
* Weight: Total Package 980g / 34.5oz


IMPRESSIONS:

I first listened to the Fubar III as a USB headphone amp, and I was a little disappointed. Sure, the Fubar III sound is pleasant, but I feel it is not up to the task for a demanding audiophile. For someone who hasn't heard better, it will be an upgrade to the built-in sound on their PC. But I tried both the headphone out and the line out, and the micro-detail and ambience of the Fubar DAC just can't keep up with my Headroom Micro DAC or Travagans Green. I have heard many other portable DAC/Amps that sound better while staying near the same price range, such as the iBasso D1 and D2, and Meier 2MOVE. Granted, some of those don't have a line out - but their headphone outs are sufficiently clean to use them as a pre-amp to feed another amp if you had to.

I did try the Fubar's RCA jack analog outputs, to feed the other amps mentioned here, and the RCA out is better than the headphone out; but it still wasn't up to my standards. Next I pulled out the Travagans Green from my basement rig, where I use it to drive an SRD-7SB electrostatic headphone transformer, so that I could do a comparison as a USB headphone amp. The Travagans green as a USB headphone amp is clearly better than the Fubar III in terms of micro-detail and space/ambience. I also felt the Travagans Green headphone out was still better detailed than the Fubar's improved line-out, and I successfully used the Green HP out as an analog line out into another amp. I have to admit however, that the Green also suffers in regards to micro-detail and ambience when it is compared to the HR Micro Stack (DAC/Amp), Predator, Pico, 2MOVE and iBasso D1 and D2 (several of which are twice as expensive).

Not only was the headphone out of the Travagans Green better than either of the outputs from the Fubar III, but the USB to S/PDIF converter (with digital outputs) in the Green also seems to contain more detail and ambience than either of the analog outputs of the Fubar III. And the Green is not even my best USB DAC! Sorry guys, but I think even my Headstage Lyrix Pro portable with USB DAC sounds better.

Again, the Fubar III doesn't sound bad, but it isn't anything special either - it is not as good as the headphone out of my Macbook, but it IS better than the headphone out of my Dell 2ghz Celeron PC. After hearing how nice the Cute Beyond sounded, I was sad that the Fubar III couldn't deliver the goods as well.

So, there you have it. I will try to post some of my own pics, and possibly be doing some opamp rolling as well - I will reserve post #2 for that purpose if I am able to get that done.

Hasta la Vista!
post #2 of 56
Thread Starter 
Reserved for photos and updates:

Update #1 - 6/13/08 9PM

I want to add a couple of comments about the Fubar III sound. My review focused on only what was different about the Fubar III, after my comments about the Cute Beyond. The frequency balance and presentation were similar to the Cute Beyond - my dislike was mainly in regards to the veil over the micro-details and ambience. Again, if you haven't heard better than your stock PC motherboard audio out or DAP, you wont know you are missing anything. The Travagans Green suffers from the same issue, but to a much lesser degree than the Fubar III, less enough that I do use and enjoy it without thinking about it.
post #3 of 56
Larry, another fantastic review by you. Nice job!
post #4 of 56
Nice review Larry, wish you had gotten a Little Country to review too as it seems interesting for its price, then you would have a full firestone shootout!
post #5 of 56
I asked Miniature Audio to send a Little Country when I had these amps on loan for my review, and in spite of an indication that they would, they never made good. I actually really only agreed to review the amps Larry reviews here in order to get a chance to review the Little Country - I was a little miffed that they didn't ever come up with one to loan me
post #6 of 56
Dang that stinks Skylab, for the price and size/looks of the LCIII it really seems like a good product. I guess it was a bad idea on their part since a review by either of you would probably have generated more sales if it sounds as good as it seems it should
post #7 of 56
Thread Starter 
Quote:
Originally Posted by Skylab View Post
I asked Miniature Audio to send a Little Country when I had these amps on loan for my review, and in spite of an indication that they would, they never made good. I actually really only agreed to review the amps Larry reviews here in order to get a chance to review the Little Country - I was a little miffed that they didn't ever come up with one to loan me
Skylab, good news. PM from miziq on 5/21/08 said,

Quote:
Originally Posted by miziq
Hi Larry,

Little country should be in stock soon. It first go to Skylab and then to you. Is this ok?

All the best

Matej
Oh, wait a minute, that was 3 weeks ago. How long is soon?
post #8 of 56
Thread Starter 
Post #2 has a minor update.
post #9 of 56
Quote:
Originally Posted by HeadphoneAddict View Post
Skylab, good news. PM from miziq on 5/21/08 said,



Oh, wait a minute, that was 3 weeks ago. How long is soon?
I do hope that actually happens! I would very much like to hear the LCIII.
post #10 of 56
and I'd very much like to hear your impressions on it
post #11 of 56
Have you tried switching the opamp in the Fubar 3? I wonder if it wouldn't stand up better to your other dacs using the same opamps.
post #12 of 56
Thread Starter 
Quote:
Originally Posted by GuyMe View Post
Have you tried switching the opamp in the Fubar 3? I wonder if it wouldn't stand up better to your other dacs using the same opamps.
I don't have a problem with the Fubar III's frequency balance, tone and timbre, or power. The problem is the missing micro-detail and ambience that takes away the Fubar's chances of having any transparency and illusion of being there. To me this is a source problem, i.e. the DAC, and not an opamp problem.

In contrast, the Cute Beyond is enjoyable as it is, and I am in no rush to roll opamps in it, but will try to do some rolling next week.

PS: Did you see my edit in post #2 that I did last night before you posted? It also addressed the issue.
post #13 of 56
I was actually thinking about this the other day, how much the differences in budget sources is in the output stage vs the DAC. In my experience changing opamps had a fairly dramatic effect on the sound and the experience of listening to music through the Fubar (2 in my case).

I'm not sure I know precisely what you mean by micro-detail, but brighter opamps certainly deliver a perceptually more "detailed" sound (tape hiss and the like). The same is, in my experience, true of ambiance as well.

I'm certainly not trying to tell you how to do your review, I just thought a comparison using the same opamps would better show the Fubar's potential. I readily admit that I could be wrong and that the differences could indeed come down to the DAC itself.
post #14 of 56
Thread Starter 
Well, I do have two sets of a pair of OPA627AU soldered onto a 2:1 adapter that I might be able to put in both the Cute Beyond and the Fubar III to compare the two with the same opamps. I also have two sets each of AD8397 and LM4562 that I could put in both amps and compare. I'll see if I can find the time to do this next week.
post #15 of 56
Nice review. The Cute seems like a bargain for only $187 exchangeable op-amps and high/low gain switch.
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