- 291 Posts. Joined 6/2012
- Select All Posts By This User
- productdigiZoid ZO2 Personal hi-fi experiencetagged by dbsaffor, 9/10/13
- productEtymotic Research ER4S MicroPro Reference Earphonestagged by dbsaffor, 9/10/13
- productFiiO E12 Mont Blanctagged by dbsaffor, 9/10/13
- productFiiO E17tagged by dbsaffor, 9/10/13
- productHeadRoom Total BitHead Headphone Amp / DACtagged by dbsaffor, 9/10/13
- productIbasso D-Zerotagged by dbsaffor, 9/10/13
- productIbasso T3tagged by dbsaffor, 9/10/13
- productIbasso T5tagged by dbsaffor, 9/10/13
- productJDS Labs c421 Headphone Amplifiertagged by dbsaffor, 9/10/13
- productJDS Labs C5 Headphone Amplifiertagged by dbsaffor, 9/10/13More
- productJDS Labs Objective2 Assembled PCBtagged by dbsaffor, 9/10/13
- productLear FSM-2 V2 Portable Headphone Amplifertagged by dbsaffor, 9/10/13
- productLeckerton Audio uha 4 slimline portable amptagged by dbsaffor, 9/10/13
- productMeier Audio Stepdancetagged by dbsaffor, 9/10/13
- productSanDisk Sansa Fuze V2tagged by dbsaffor, 9/10/13
- productShure SE530 Sound Isolating Earphonestagged by dbsaffor, 9/10/13
Related Forum Threads
- Would like some advice on choosing a portable amp. + DAC [single unit] Last post on 6/14/13 at 8:51am in Portable Headphone Amps
- Giant List of sub-$200 portable DACs w/ their chips & price Last post on 1/19/14 at 10:51am in Dedicated Source Components
- Best $100 amp? Last post on 9/18/13 at 7:34pm in Portable Headphone Amps
- [Impression] FiiO X3 – High Fi, Low Price. Last post on 3/9/14 at 10:04am in Portable Source Gear
- Ultra-portable Amps Last post on 8/26/12 at 2:57pm in Portable Headphone Amps
2013 Head-Fi Winter Gift Guide (Portable Amps, DACs, & DAPs)
Last edited: 2/5/14
- 2013 Head-Fi Summer Buying Guide (Portable Amps, DACs, & DAPs...Last edited: 7/26/13
- 2013 Head-Fi Summer Buying Guide (Introduction)Last edited: 7/23/13
Summary: These headphones give an accurate picture of what the producers had in mind when they mixed their music because they have a well-balanced, present, but not over-powering bass. Songs...
My current set. My favorite and my private oasis. These beauties will cut out most if not all ambient noise like while driving in a car and household noise when the music is flowing. I became a fan...
I was asked to listen to the Musical Fidelity MF100 and received them about 4 weeks ago. I get quite a lot of headphones through my door, I only review the ones I like and I like these a lot. I...
Got the SE846 last week and did some hours of comparison with my current SE535. My bias was towards keeping them - I like flagship products as a "there is nothing better" products, i.e. do not...
So I finally broke my go to earbuds, and went searching for a replacement. I was actually so disappointed with these things that I made it a point to get out and put out a review. Bass continuously...
The Sub-$200 Portable Amps Shootout – 13 (+11) amps compared - Page 8post #106 of 4349/9/12 at 8:15pmObjective2 isn't really a pOrtable amp.
Gear mentioned in this thread:post #107 of 4349/9/12 at 8:22pmpost #108 of 4349/9/12 at 8:27pm
Lol, it needs to fit in my skinny jeans. Which is why I want either the t3 or e11 or some other such small amp that's the best for drive a 50 olm headphone (meaning at least100 mw at 50 olms according to the maker).
Edited by clairyvic - 9/9/12 at 8:37pmpost #109 of 4349/9/12 at 10:24pmQuote:Originally Posted by MeeHungLowe
I think one of the challenges for new amp buyers is the difference between high current, high voltage & high gain. I know it confuses me! All I know is that low-impedance headphones tend to hiss and sound bad if the amp's gain is too high - but I really don't know why - I'm guessing it is because gain is actually a voltage increase? And if the amp gain is too high for a low-impedance 'phone, then you can overdrive the 'phone (supply too much voltage) - is that correct?
High gain (high multiplier of input voltage) causes high voltage, but there's a separate important measure, clipping voltage, which is the maximum voltage supplied by the amplifier regardless of gain. Low gain is usually better than high gain, since gain amplifies input noise and many potentiometers have channel imbalances most pronounced in the lower part of range. Switching to higher gain is only recommended if the audio is too quiet. (almost always)
Low impedance headphones require an amplifier with exceptionally low current noise and higher maximum output current - they tax the current stage more than the gain stage. Too low maximum current will cause current limiting and sagging, which causes harmonic distortion.
Reducing current noise is usually harder than reducing voltage noise and requires careful circuit layout and design.post #110 of 4349/9/12 at 10:38pm
I wonder when someone's going to make a smaller smd version.post #111 of 4349/9/12 at 10:54pmQuote:
Not really, a good amplifier will do well both with highly sensitive IEMs and far less sensitive headphones, within limits.
Usually the main source of limitations is at the higher impedance end due to the battery voltage - most amplifier producers are loathe to include step-up circuits, as they are expensive, usually power hungry and require even more care in circuit design to not introduce their switching noise into audio. Similar, but much less pronounced problems are faced by designs using charge pumps to synthesize the other rail (negative voltage) for the opamps.
The low impedance IEMs on the other hand can be affected by high output impedance of the amplifier. This will cause frequency response changes in concert with natural impedance curve of the device, which mostly affects balanced armature IEMs, esp. multi BA; and lack of electrical dampening, which will mostly hurt dynamic driver and orthodynamic quality, causing harmonic distortion.
Moving armatures are inbetween with regards to both of these effects.
So, the ideal generic source would provide: relatively high maximum output current (for very low impedance IEMs and orthodynamic headphones), near zero output impedance (for BA IEMs) and high maximum voltage (for high impedance headphones). Obviously enough power to drive something high impedance.
Rebuilding O2 into SMD should be relatively easy, as all of the components have SMD versions. It won't be too much smaller though.
The main source of girth in O2 is the two 9V batteries. Replacing them with li-ion or something else thinner (which could be laid above the PCB) would require replacing the power management circuit altogether - most of the bottom part of PCB. (near the batteries) Needs care to not break the performance.
Edited by AstralStorm - 9/9/12 at 11:43pmpost #112 of 4349/9/12 at 11:56pmThread Starter
NwAvGuy prohibits any modification to the design without his consensus (in the GPL) though...post #113 of 4349/10/12 at 4:33amQuote:
No, the GNU GPL permits modifications.
The O2 is released under a "Creative Commons Attribution-NoDerivs 3.0 Unported (CC BY-ND 3.0)" license. Although real license interpretation requires a lawyer, I doubt this CC license prevents shrinking the board or using SMD parts.
Edited by HamilcarBarca - 9/10/12 at 6:02pmpost #114 of 4349/10/12 at 5:24amThread StarterYes, you are right. It is under CC. However, here is what the guy said: "...the O2 is offered only under a “no derivatives” license. Put simply, you can’t modify it or use it as part of a different design and then offer it to others without prior approval. This is to help prevent inferior versions of the O2 that might disappoint whoever buys/builds them. Even the PC board design is an essential component of the O2’s performance and changing it could have dramatic consequences...." If course, one can always choose to disregard this sort of things...post #115 of 4349/10/12 at 6:50am
Exactly - the author of such a PCB/layout would have to contact NwAvGuy to get his approval. Nobody prevents using the same design principles, similar components, then calling it differently though.
Perhaps you could even call the design inspired by O2.
Edited by AstralStorm - 9/10/12 at 6:56ampost #116 of 4349/10/12 at 7:31amAstralStorm,
You're right about the O2-inspired design... I'm also not a real lawyer (wouldn't want to be, tend to get so technical about EVERYTHING in life), but someone could come along, make a few changes, and call their amp something different. I mean, that's basically what happened with Fred_Fred_2004's 3-channels amp, right? Mini^3 inspired?
Also, in regards to your reply to my post, it seems like we mostly agree... just in different words. I was basically taking a stab at a shorter, layman's explanation of "proper" amping so that clairyvic could make his own decision. Since he/she kinda glossed over his needs, I was trying to just give him a general answer. An answer besides "just buy one and see if you like it," lol!post #117 of 4349/24/12 at 12:48pmClieOS, any possibility of doing that tube amp review? Also, this would probably be irrelevant to the portable amps shoot out, but have you heard of the Indeed G3 Tube Hybrid or Bravo V2 tube hybrid desktop amps? I have suspicions that they'll suit Q701's better than a FiiO E11 (though the top picks for the sub-$200 round up should do nice as well...)post #118 of 4349/24/12 at 7:43pmThread StarterQuote:Originally Posted by Evshrug
ClieOS, any possibility of doing that tube amp review? Also, this would probably be irrelevant to the portable amps shoot out, but have you heard of the Indeed G3 Tube Hybrid or Bravo V2 tube hybrid desktop amps? I have suspicions that they'll suit Q701's better than a FiiO E11 (though the top picks for the sub-$200 round up should do nice as well...)
BL-2's review has actually been posted a week ago, you can find it here:
Never listen to those eBay desktop tube amp before. I haven't had much use of desktop amp (plus I already have a hybrid amp from FireStone Audio) so I never think of picking one up.post #119 of 4349/26/12 at 7:35am
I was looking at the Leckerton Audo site and noticed that the UHA-4 can be ordered with a couple different output OP amps. The one in the review was done with OPA209 what is the difference between that and the standard AD8610ARZ that seems to come standard.
Thanks for any input you can give
Mikepost #120 of 4349/26/12 at 8:14am
I have to hand it to iBasso.
I recieved a D-Zero a week ago and it had quite a bit of noise in the DAC section(amp section is silent using with ipod). I contacted iBasso and they sent me out a new one right away. I recieved that one yesterday and I have to say, it's a nice little amp/DAC.
Dead quiet, great sound quality, and more than enough power.
I guess I'll use one with the ipod and the other with the computer...
- The Sub-$200 Portable Amps Shootout – 13 (+11) amps compared
Gear mentioned in this thread:
- 2013 Head-Fi Summer Buying Guide (Portable Amps, DACs, & DAPs...
- › Grado Fan Club! 43 seconds ago
- › New WA7d Fireflies with Two Digital Inputs 2 minutes ago
- › Sennheiser HD 6,7 & 8 DJ Appreciation thread. Opinions, reviews,... 4 minutes ago
- › Toxic Cables - The Appreciation Thread 6 minutes ago
- › Shure SE846 Appreciation Thread 7 minutes ago
- › What Are You Listening To Right Now? -New thread, new rules. Please... 8 minutes ago
- › The iBasso DX50 Thread - Latest firmware: 1.2.8 10 minutes ago
- › **Hifiman HE-400 Impressions and Discussion Thread** 10 minutes ago
- › Pictures of Your Portable Rig (part XVI) 10 minutes ago
- › Guitar-fi anyone? 12 minutes ago
- › Sennheiser HD 25-1 II Professional Headphone by aeromaniac
- › Ultimate Ears 500 by echo1284
- › Musical Fidelity MF-100 High Quality On-Ear Headphones by astroid
- › Shure SE846 Sound Isolating™ Earphone by agistrilink
- › NCredible NErgy In-Ear Headphones by Monster® by tevbax
- › Audio-Technica ATH-M50x by De_klusjesman
- › Klipsch S3M-Blue-HP In-Ear Headphone, Blue by DaddyMojo
- › Unique Melody Mentor acrylic universal/custom by svyr
- › Fischer Audio TBA-04 IEM by exsomnis
- › Edifier H850 by ClieOS
- › The Best BASS Headphones ( a Head-Fi Wiki) by Hawaiibadboy
- › 2013 Head-Fi Winter Gift Guide (In-Ear... by joe
- › 2013 Head-Fi Winter Gift Guide (Over-Ear... by joe
- › 2013 Head-Fi Winter Gift Guide (Over-Ear... by joe
- › Adjusting bias on Stax tube amplifiers by ardilla
- › Headphone Power Calculator Spreadsheet by robrob
- › Headphone-to-Speaker-Amp Interface With... by robrob
- › Headphone Resistor Network Calculator by robrob
- › 2013 Head-Fi Winter Gift Guide by jude
- › 2013 Head-Fi Winter Gift Guide (Introduction) by jude