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REVIEW: Leckerton Audio UHA-6S USB & TOSLINK DAC/Amp

post #1 of 16
Thread Starter 

EDIT: May 22, 2011

First a little background. I have been heavily involved in high-end audio for decades, but I am a relative newcomer to mobile audio. I have only been using it for around 5 years, and have only recently come up with a system that I can call high-end, due in no small part to the excellent information to be found on this site.

 

I have long had the suspicion that one of reasons it is difficult to achieve excellent sound with a portable setup is the low power DACs that most of these units employ. So I felt it was imperative to pick a unit with a S/PDIF input.

 

I don't have the opportunity to try out a number of units, so I rely on technical information. It is helpful that I come from an EE background and have some professional and audio amateur circuit design experience. Leckerton Audio is more forthcoming in design details than some of their competitors - I suspect that this is more due to most companies not thinking the information is of interest than it is to secretiveness. Leckerton has good detail on their website and I was able to get more detail from them via email. One of the ways the Leckerton is different from the competition is in the power supply. This is an area that seems to be an afterthought in many models but it is critical to performance. Many (though by no means all) designs do with a single supply rail. The Leckerton uses three supplies, a dedicated 5V rail for the DAC, and a bipolar +- 6V supply for the DAC output filter stage and the DAC stage. Why does this matter? First the noise generated by the DAC is isolated from the analog stage. More important in my opinion is that the analog section can be all DC coupled. Using a single supply rail means that the output will be referenced not to ground but to approximately 1/2 of the supply voltage. I don't know of any way to get that signal into a usable state other than using a very large coupling capacitor. How large? A 20Hz f3 with a 16 ohm load requires approximately 500uF and indeed the two amps I was able to get circuit data on uses 470uF capacitors in the output. These are often non-polarized electrolytics which are notoriously non-linear. I found one design that uses tantalums bypassed by film caps - an improvement but still the best output capacitor is none at all. Most manufacturers don't publish their power supply details, but there are ways to get an idea. If a unit has a DAC but still uses a 12V charging port it is likely to be single rail. If you are using a DC to DC converter there seems little point in not using the USB power for charging. If a unit uses a pair of 9V batteries (which I have seen) it is almost certainly bipolar. Other than that, rather than asking the vendor, you can look at the circuit and see if there are large value coupling capacitors. As far the other technical details, I will readily admit I am not up on current op-amp choices - but the Leckerton's are socketed if you want to roll your own. The DAC is as I have alluded to earlier, a home audio unit, the highly regarded Cirrus Logic CS4398. This is a higher quality DAC than used in my Marantz pre-amp/processor. And unlike one competing product that uses home type DACs the Leckerton does not have a steep high frequency roll-off. The Leckerton gets 15 hours battery run time when using TOSLINK compared to 35 using line in, but still good enough for an international flight. And you can power it from a portable USB supply if push comes to shove, something you can't do with a 12V charged unit. In keeping with the philosophy of providing deep technical information, Leckerton has published a full distortion test with a comparison to a competitor: http://www.leckertonaudio.com/2011/01/uha-6s-harmonic-distortion

 

On to the listening impressions. I first compared the Leckerton to my previous amp, the Total AirHead, using the Cowon D2 line out. This is a fine amp, excellent value, and I would still recommend it in its price range. This is a single supply amp BTW with NP electrolytics output caps. The Leckerton bettered it in every respect.

 

Where I was really interested in the results was with a TOSLINK input so I was eager to try out the Leckerton with my "new" iRiver H140 (Rockboxed) which I purchased from a head-fi'er. I use a mixture of FLAC and 256k MP3 when running portable. Not having another high-end portable rig to compare it to, I tend to reference my home theater system (see .sig). The Leckerton really doesn't have much of a sonic signature. It is extremely neutral, as a well designed piece of electronics should be. It does not suffer at all in comparison to my Sunfire amp - in fact the best thing I can say is that the rig does not sound like I have come to expect from portables - I come up with words like "rich" and "full". Attacks are not at all compressed, which indicates that there is no slew limiting going on. I have heard details in this setup that I haven't even caught with my home theater (there are some advantages to headphone listening). The Leckerton did an awesome job of keeping bass taught and well defined (I suspect a low output impedance). There is one area though in which the Leckerton really goes above and beyond, and that is in sound stage. The sound stage with this rig is huge. You have to hear it to believe it. The unit has plenty of drive capability. Orthodynamics have a reputation of being difficult to drive, but my Thunderpants sound fantastic with this amplifier. At no point do I get any feeling that the amplifier is limiting the sound quality of the rig. I prefer the high gain setting with these headphones, though the amp has enough output to drive them with the low gain setting.

 

Construction is solid, and controls are pleasant to use with no artifacts in operation.

 

Lastly, I like to support domestic industry. I believe this is the only US made DAC/Amp with an S/PDIF input (I will likely get corrected by someone - I don't know all that is out there). However I can state that the primary US made competition (fine units I am sure) run around double what the Leckerton does. I don't know how they are able to do it.

 

First rate design, excellent construction, world class sound quality, domestically produced at a comparitively bargain price and great customer support. I can't recommend the Leckerton UHA-6S too highly. And if you don't need the TOSLINK input, the UHA-6 is available for $20 less.

 

Here is a picture of the whole rig.

tp.jpg

 


Edited by sbradley02 - 5/22/11 at 9:13am
post #2 of 16

Nice review! I was wondering really how good the Leckerton products were. I would consider it because thy are an American company, but unfortunately they do not have any balanced amps. 

post #3 of 16

Thank you for the write up, very well done. Your impressions mirror my experience with the UHA-6S. It's just a phenominal amplifier and I wish more people would give it a try.

post #4 of 16

Wow, US made, but looks like a nice challenger to iBasso.  I wish them luck!  

post #5 of 16
Thread Starter 

Thanks for the comments.

 

Leckerton is not very well known, even on this site where folks are familiar with a lot of brands, and I hope to help remedy that.

post #6 of 16

Thanks to both you and Project86 for reviewing this.  I just bought my first DAC from HotAudio, and I'm looking for something US built for a tube amp as well...otherwise, i might resort to a LD i+.  I spend about 14 hours a day at my desk out here, and the bulk of that is with headphones on, so that is going to be my work rig.

 

Anyway, I was just sitting here thinking about what I should do for my poor little laptop in my room and for my D2 when I travel.  I've been browsing for about a week now for a solution to this problem and have come across an awful lot of reviews.  I'm no audiophile; I just want a good, mid-fi portable dac/amp.  After reading Streeter's review of the Leckerton uHA-4 last night and then you guys' reviews tonight, I'm most definitely going to be picking this up.

post #7 of 16
Thread Starter 

Cool, glad the review was of help!

 

Your impressions after you receive your amp would be welcome.

post #8 of 16

Hello,

 

This is my first post in these forums. After reading through the forums for a good portable headphone amp/dac, I decided to buy the Leckerton Audio UHA-6S which I received this past Saturday. Since I only listen to CD quality audio, I settled with the 16 bit DAC capability through USB which met my needs. I've been using the amp/dac with my Zune HD via optical out on the A/V dock with 320kbps or 245 VBR V0 MP3s encoded with LAME and I get excellent results with all the headphones I've tried with it with the exception of the AKG Q701s which didn't sound the greatest (in Techno, and alternative music with alot of highs). The HD600s sounded phenomenal with the amp having plenty of power to spare, as did the HD25-1 IIs with GAIN set to high. As for IEMs, all I've tried are the SONY MDR 7550s with the gain setting turned off and they too sounded exceptional for all types of music. The Leckerton UHA-6S seems to add a decent amount of bass impact to fast headphones such as the Sennheisers and Sony Studio IEMs that I tested. IT also contributes to increased soundstaging and I also hear details that I've missed while listening to the source without amplification (that alone makes the purchase worth it). However, as for the AKG Q701s, the treble seemed a little harsh (anyone had this problem?) - is it because the headphone is "slow"?. As I am writing this, I am listening to the AKG Q701s on the UHA-6S digitally connected to the Zune HD A/V Dock so my basis for this claim is verified by my most recent experience.  

 

Since the Zune HD lacks a lineout for portable use, I tried the AMP via a generic HOSA 8" mini-mini connector connected to the headphone out, turned the volume on the Zune HD all the way up to 30 (volume at max is comparable to the volume generated by the digital signal via A/V dock) and got decent but not fantastic results. The clarity from the optical input of the A/V Dock wasn't all there in analog mode and there is some graininess in the treble and adds a bit (not alot) of warmth (probably the warmth from the headphone out) to the music but overall, I found the amp to have positive results towards increasing the soundstaging and overall clarity when compared to headphone out from my Zune HD. Again, I tested the analog input of the UHA-6S with the headphones I have available. The results were essentially the same as utilizing the optical input save for a bit of graininess and a bit of warmth from the headphone out on my portable source.

 

Overall, I think the Leckerton Audio UHA-6S is a very good entry point for me into the portable headphone amp/dac world and is a keeper. Its built pretty solid, doesn't make the headphones sound unbalanced at low volumes, and it is of the same width and length as the Zune HD (too bad, not height) so I can wrap some elastic velcro to hold both in place. Since I have owned no other portable headphone amp or dac, I cannot compare to others except for the ASUS XONAR Essence STX (which appears to play nice Q701s as well as the others). I can only say that with only about 10 hours of burn in, it works wonderfully with the Sennheiser HD600s, HD25-1 IIs, and Sony MDR-7550s.  Now I have to think about getting a portable source with a dedicated line-out or rarer still, one with an optical output. I wish I kept the PCM-D50 to use with this AMP via optical out but I returned it to BHPhoto after a week of owning it...

post #9 of 16
Quote:
Originally Posted by manicamp View Post

Hello,

 

Since I only listen to CD quality audio, I settled with the 16 bit DAC capability through USB which met my needs. I've been using the amp/dac with my Zune HD via optical out on the A/V dock with 320kbps or 245 VBR V0 MP3s encoded with LAME and I get excellent results with all the headphones I've tried with it with the exception of the AKG Q701s which didn't sound the greatest (in Techno, and alternative music with alot of highs). 

 

Just curious how you get CD quality audio using lossy compression?  The formats you list are lossy.  If you want lossless, the bitrate will be much higher.

post #10 of 16

I had gotten the dac for my alienware m11x which I use to play 16 bit 44.1 khz FLAC files using FOOBAR (WASAPI) when I am using my laptop. The onboard sound controller of the laptop is better than most but the DAC from the UHA-6S outputs clean and interference free sound (minimal hiss using 16 ohm IEMS - less hiss than ASUS Xonar Essence STX).

post #11 of 16
Thread Starter 

As far as portable digital sources go, there is the venerable iRiver H140 which is what I am using currently.

 

I hope to have a USB source within the next few weeks.

post #12 of 16

Also the QLS QA350 has an optical output, but it is one of those mini-jacks that requires a 3.5mm to toslink adapter. Not the easiest or most convenient DAP in the world but it gets the job done for cheap, and sounds amazing with the Leckerton. 

post #13 of 16
Thread Starter 


Yes, that is a sweet looking piece and reasonably priced. WAV only support is what discouraged me, though converting everything to WAV is not all that especially difficult. Cool to hear that it is a good match for the Leckerton.

You can get custom made mini-Toslink to Toslink cables, that is what I am using.

Quote:
Originally Posted by project86 View Post

Also the QLS QA350 has an optical output, but it is one of those mini-jacks that requires a 3.5mm to toslink adapter. Not the easiest or most convenient DAP in the world but it gets the job done for cheap, and sounds amazing with the Leckerton. 



 

post #14 of 16
I will get a leckerton 6hs and compare to the iBasso D12 and D6.
post #15 of 16
Quote:
Originally Posted by mrspeakers View Post

I will get a leckerton 6hs and compare to the iBasso D12 and D6.


Look forward to it.  Which opamps did you decide on? 

 

On the optical front let's just say I've been through about 9 different cheapo plastic optical cables just for the sake of curiousity.  I leave it at 'interesting' results.

 

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