[RAQemUP]

Just a quick update.

Sorry it's taking me so long to review but I have been a bit busy with exams and work. I will be having my review up sometime this Tuesday night.

I have been doing some extensive listening with Sennheiser HD 25-1-II headphones (both pleather pads and velour) and I am currently testing the LODs out with my Sennheiser IE8. I am testing with the 2 Fuze LODs of ClieOS as well as a Fuze LOD of my own that terminates in a 3.5mm jack so I can use any 3.5mm to 3.5mm cable. Of course I also tested out from headphone out to line in of the portable amps. The portable amps I am testing with are the Corda Headsix and the Ibasso D2 Viper with rolled opamps.

I'll try to keep the review short and concise when I do.

PS. @Upstateguy: I only use the mp3/ogg playback of the Fuze. I haven't touched the FM radio since I originally bought the Fuze just to test out how it sounded that first day of purchase. At least, that's what I think you were asking about.

 

[upstateguy]

Quote:

Originally Posted by RAQemUP /img/forum/go_quote.gif Just a quick update. Sorry it's taking me so long to review but I have been a bit busy with exams and work. I will be having my review up sometime this Tuesday night. I have been doing some extensive listening with Sennheiser HD 25-1-II headphones (both pleather pads and velour) and I am currently testing the LODs out with my Sennheiser IE8. I am testing with the 2 Fuze LODs of ClieOS as well as a Fuze LOD of my own that terminates in a 3.5mm jack so I can use any 3.5mm to 3.5mm cable. Of course I also tested out from headphone out to line in of the portable amps. The portable amps I am testing with are the Corda Headsix and the Ibasso D2 Viper with rolled opamps. I'll try to keep the review short and concise when I do. PS. @Upstateguy: I only use the mp3/ogg playback of the Fuze. I haven't touched the FM radio since I originally bought the Fuze just to test out how it sounded that first day of purchase. At least, that's what I think you were asking about.

Hi RAQ

Your rig looks interesting, do you have any pics of it?

Too bad about not using the FM. I like FM when I'm mobile. I even like the PBS DJs and the news breaks.

USG

 

[kostalex]

ClieOS, may you provide us with some statistics already?

 

[ClieOS]

Quote:

Originally Posted by kostalex /img/forum/go_quote.gif ClieOS, may you provide us with some statistics already?

What kind of statistics?

 

[kostalex]

Who hears the difference, who does not, how much is the difference, does it worth to hassle with additional module (LOD).

 

[ClieOS]

Quote:

Originally Posted by kostalex /img/forum/go_quote.gif Who hears the difference, who does not, how much is the difference, does it worth to hassle with additional module (LOD).

I don't have any statistics for you, but as far as I know, none who hears the LOD for his/herself disagree that there is a difference b/w LO vs. HO.. As for whether it worths the effort of making a LOD or not, some say yes and some say no so much - each of them has his/her own reasoning based on listening preference and gears difference. I guess the best way to make an assessment is to read the individual impression (on the first post) and not rely on any general statement.

 

[RAQemUP]

Ok people. Here is my review.

To recap, the tested headphones were a Sennheiser IE8 (bass knob on lowest setting) and Sennheiser HD 25-1-II (with both pleather and velour pads) with stock steel cable and the tested portable amps were Corda Headsix and Ibasso D2 Viper with rolled opamps. I tested with 3 Fuze LODs: 1 with visible caps on the dock connector, a 2nd without visible caps on the dock connector, and a 3rd with no visible caps on the dock connector and had a 3.5mm line out jack instead of a cable terminated with a 3.5mm plug like the previous 2. The first 2 docks were supplied by ClieOS while the 3rd dock was one I purchased off of ebay sometime during the summer. I also used a mini to mini cable to test both headphone out to amp and dock 3 to amp. I will try to be as short and to the point as possible.

First let me say that the Sansa Fuze already sounds great to me straight out of the headphone out. And the sound gets even better by amping, regardless of whether using a LOD or a 3.5mm to 3.5mm from headphone out. Just by amping through headphone out, the soundstage increases, the bass gets more meat, the vocals are smoother and slightly laid back versus listening through the DAP headphone out, and simbilance in some music tracks were almost completely removed. The Fuze is very much worth amping IMO.

Second, to my ears, the IE8s responded much better to being amped than the HD 25-1-II did. With the HD 25, I could only tell a difference between listening straight out of the Fuze headphone out versus the portable amps regardless of the options. All the cable amping options sounded much too similar to me to differentiate between them on the HD 25. I chalk this out to needing a stronger amp to being able to hear a true difference. Also, the D2 Viper was clearly better over the Headsix. With the IE8 the difference was night and day while with the HD 25 the difference was only a small step up. Using the velour pads over the pleather pads on the HD 25 killed some of the bass impact. Though the velour pads are more comfortable, I ended up preferring the pleather pads for the better sound. It's not like the pleather pads are uncomfortable anyways.

Third, though there is a clear difference between using an LOD over just a mini to mini cable, the difference is not drastic in most music genres. In all the tests, the LODs with no visible caps sounded almost exactly the same and were pretty hard to differentiate from each other whereas the LOD with visible caps was clearly superior. In rock and acoustic music (ie Radiohead, Stone Temple Pilots, Jeff Buckley, James Taylor, White Stripes, Soulfly, Nevermore, Mudvayne, etc), using an LOD over a mini to mini cable made the music only a tad smoother sounding as well as widening the soundstage just a bit more. The LOD with visible caps gave bass guitars and drum hits just a bit more ooomph.

In electronic music (ie Royksopp, Infected Mushroom, Prodigy, Orbital, and some of the "Does It Offend You, Yeah" tracks, etc), the difference between amping from headphone out against LOD was much more evident. The LODs with no visible caps made all the beats much easier to seperate from each other and made the bass have terrific definition. The LOD with visible caps one upped that with a much clearer and stronger bass footprint. I was tapping my foot and nodding my head with that one. Highly immersive that LOD is.

To sum it all up, if your headphones are IEMs and you listen to a bit of electronic music, using a Fuze from a LOD to an amp is great. Otherwise, if I was tight on money, I would hold back from trying to acquire a LOD.

However, if you are on this website, you are someone who is trying to improve your music listening experience. Even if it is a small increase, it may be worth it to invest your hard earned coin on it.

Please, no flaming. This is purely all my humble opinion and my ears are different from everyone else in this big, huge world.

 

[ClieOS]

Thanks for the impression, RAQemUP. Remember to PM Woody469 for his contact info in order to send him the LODs.

One thing I want to add: the 2nd LOD without visible caps on the dock connector actually doesn't have any caps inside at all and it is meant to be use with amp which already have coupling caps built-in (i.e. cmoy, E5, etc.)

 

[Woody469]

Quote:

Originally Posted by ClieOS /img/forum/go_quote.gif Thanks for the impression, RAQemUP. Remember to PM Woody469 for his contact info in order to send him the LODs. One thing I want to add: the 2nd LOD without visible caps on the dock connector actually doesn't have any caps inside at all and it is meant to be use with amp which already have coupling caps built-in (i.e. cmoy, E5, etc.)

I've sent my address on to RAQemUP so he can send LOD(s)?

First I want to say Thank You to RAQemUP for his time and his review. Great job.

After reading ClieOS's comment in regards to the LOD "without" the visible caps, I needed to reread the review. It's very telling in that it seems, with some music, it is better to have a "capless" LOD. I was under the impression that if a person used a capless LOD with an amp that doesn't have coupling caps built in, damage "could" occur downstream. I think I will skip using that LOD as I have no idea if the amps I intend to use have caps or not.
Again, Thank You RAQemUP for your impressions and to ClieOS for the opportunity to do such a comparison.

 

[RAQemUP]

Yeah, just would like to thank ClieOS for the opportunity to try out some different LODs.

I still have no idea what is inside any of the LODs. heh

In restrospect, I should have thrown in a Grado SR 325i listening impression in there and maybe tried the HD 600 cable on the HD 25-1-II. The SR 325i is highly responsive to amping and I read that the HD 25 really shine when the stock steel cable is switched to copper cables like the HD6x0 cables. I guess I just decided without any effort (heh) to just keep the review strictly to portable phones.

 

[ClieOS]

Quote:

Originally Posted by Woody469 /img/forum/go_quote.gif I was under the impression that if a person used a capless LOD with an amp that doesn't have coupling caps built in, damage "could" occur downstream.

Yes, you're right.

In principle, the less components in the signal path the cleaner the sound. Putting cap in series (one in LOD and one in amp in each channel) is generally a bad idea as it decreases the total capacitance and makes the bass cutoff point higher. However, some people find the coloration of adding extra cap actually sound better. Well, that's another story of its own.

 

[upstateguy]

Quote:

Originally Posted by Woody469 /img/forum/go_quote.gif I was under the impression that if a person used a capless LOD with an amp that doesn't have coupling caps built in, damage "could" occur downstream. I think I will skip using that LOD as I have no idea if the amps I intend to use have caps or not.

I was under the impression that a capless LOD was dangerous to use also.

Quote:

Originally Posted by ClieOS /img/forum/go_quote.gif Yes, you're right. In principle, the less components in the signal path the cleaner the sound. Putting cap in series (one in LOD and one in amp in each channel) is generally a bad idea as it decreases the total capacitance and makes the bass cutoff point higher. However, some people find the coloration of adding extra cap actually sound better. Well, that's another story of its own.

- I wonder if you could go into some detail as to what kind of damage a capless LOD might do because this has become a little confusing?

- How can do you determine if its safe to use a capless LOD with your rig?

- Do you feel, that in general, if you're not sure of the circuitry in your amp, it's probably better to be on the safe side, as Woody posted, and not use a capless LOD?

- What kind of damage can occur if the resistor is left out of the dock?

- And finally, is there some way to tell/measure if the proper resistor is there before using a LOD purchased on ebay, for instance?

USG

 

[ClieOS]

Quote:

Originally Posted by upstateguy /img/forum/go_quote.gif - I wonder if you could go into some detail as to what kind of damage a capless LOD might do because this has become a little confusing?

First of, to under stand the underlying danger of caped vs. cap-less, you need to understand that music is in AC form (that is what caused the electric coil to vibrate in an magnetic field, as DC will just push the coil to one side). However, almost all output from a DAC chip has some DC offset (on top of the AC signal). If this DC voltage is small enough, it will push the coil in one side while the AC signal can still be turned into music. If the voltage is too large, it will either knocks the coil out of alignment (bad!) or heat up and damage the coil (extremely bad!).

In typical design, a RC circuit (R = resistor; C = capacitor) is included just before the output to filter out any DC voltage. However, since Sandisk decides to left out the RC circuit for the line-out, the DC voltage (1.4V in fuze's case) will make it way to any downstream component that doesn't have an input cap to protect itself (*though not confirmed, I think it is Sandisk's idea to implement the RC circuit on the accessories side, just to save space on the player motherboard). If the DC makes it way to the amp, the amp will amplify the DC by whatever gain the amp is on, then send the mixture of AC and DC to the headphone. i.e. Amp with gain of 2 will output 1.4V x 2 = 2.8V DC. If the DC voltage is large enough and the headphone is incapable of handling it, damage will occur.

Quote:

Originally Posted by upstateguy /img/forum/go_quote.gif - How can do you determine if its safe to use a capless LOD with your rig?

If you know your amp has input or output caps, then it is safe to use a capless LOD.

A fast and easy way to determine whether the amp has in/output cap or not is to connect the amp and Fuze with a capless LOD, plays music and turns the amp up (around half the volume should be enough) then measures the amp's output left/right channels against the ground via a voltmeter. If there are caps, it will be zero volt (in real practice, there will be a very tiny voltage, much much less then 1V presents most of the time, like 0.001V). If you detects DC voltage on the amp's output, then the amp doesn't have any cap.

Quote:

Originally Posted by upstateguy /img/forum/go_quote.gif - Do you feel, that in general, if you're not sure of the circuitry in your amp, it's probably better to be on the safe side, as Woody posted, and not use a capless LOD?

Yes.

As explained before, it is technically better not to put two caps in series; but if you are not sure, then you should always choose to use a cap'ed LOD just to be safe.

Quote:

Originally Posted by upstateguy /img/forum/go_quote.gif - What kind of damage can occur if the resistor is left out of the dock?

In the RC circuit, it is the capacitor that actually does the filtering (as DC can not pass through cap, only AC can). The resistor is there to serve mainly two functions: 1) to behave as a stunt, allowing any DC leakage to bleed to the ground so it won't go to the amp/headphone. 2) to lower the overall impedance so the problem of dielectric absorption can be minimized (= minimizing the noise caused by the cap itself). I am not an EE so I won't try to go into any detail, but there is a paper by Walter G. Jung and Richard Marsh called "Picking Capacitors" that has all the detail.

To focus back to the 1st function, there are generally several situations where resistor can be useful:

One, when the caps is faulty and allows DC voltage to leak through. This is rare but it can happen as the cap aged. The best way to determine whether the is a leakage is by regular check up via a voltmeter. There should not be any DC voltage on the LOD output. Also, every cap has its own rated lifespan (usually from 1000hrs up to ten of thousands). So reusing old cap poses higher possibility for caps' failure. In situation like this, resistor help to bleed away some of the voltage, but it isn't 100% safe and the cap should be replaced right away.

Two, it takes time to charge up a cap before it can filter the DC. The larger (capacitance wise) the cap, the more time it needs. Before the cap is charged up, a small amount of DC will leak. A small value resistor helps to bleed this voltage away. However, if the capacitance isn't very big, then it will charge up fairly quick and the danger that DC leakage posed is minimum. In the worst case scenario where a big surge does happen, there is no guarantee that the headphone will survive even if there is stunt resistor in place. This is why a good practice for any amp user is, you should turn the source's power up first ,follow by the amp (always in minimum volume) before plug in your headphone into the amp. This will help reduce the chance that a surge coming from the source or the amp from damaging your headphone. If you follow the right way of connecting and turning on/off your rig, your headphone will be safe.

So, the resistor can be omitted if 1) the cap isn't faulty (using a good quality cap helps), 2) follow the right on/off procedure and 3) can't hear any difference b/w resistors / no-resistors.


Quote:

Originally Posted by upstateguy /img/forum/go_quote.gif - And finally, is there some way to tell/measure if the proper resistor is there before using a LOD purchased on ebay, for instance?

Not to my knowledge.

Again, I am not an EE but those above are to the best of my knowledge. If anyone find error in it, please point it out. Thanks.

 

[upstateguy]

Quote:

Originally Posted by ClieOS /img/forum/go_quote.gif First of, to under stand the underlying danger of caped vs. cap-less...... ......Thanks.

That was a great explanation, thanks ClieOS.

So the damage is to the headphone not the amp or the Fuze.

Three more questions if you please:

- Can the native DC of 1.4V from the line out of the Fuze damage my HD650s if left unamped?

- My M^3 has a gain of 11. That would be 15.4V of DC when amplified. So my question is, how much of the 15.4V goes into my headphones if I don't have the volume turned up very much?

- I find that even with my HD650s, I listen at around 70% of full volume from the Fuze's HPO. This is loud enough for all my general listening. As you know, I also have a Griffin dock. Since the LO volume is equal to 100% volume (on the "Hi" setting) from the HPO and I am only using 70% of the volume which the dock delivers to the amplifier, I end up using the amplifier as an attenuator. So my question is, is there any advantage to using the amp as an attenuator or am I better off just using 70% of the HPO?

Thanks.

USG

 

[ClieOS]

Quote:

Originally Posted by upstateguy /img/forum/go_quote.gif - Can the native DC of 1.4V from the line out of the Fuze damage my HD650s if left unamped?

Any DC voltage to headphone is not a good news, but when, where or how the damage will occur are determined by the electrical properties of individual headphone. From experience, dynamic seems to be more tolerant than balanced armature on DC voltage, and bigger dynamic transducer tend to be better tolerant than smaller one. In any case, I am not familiar enough to say whether 1.4V DC will damage HD650 or not, but the rule of thumb is simply not to apply any DC to headphone.


Quote:

Originally Posted by upstateguy /img/forum/go_quote.gif - My M^3 has a gain of 11. That would be 15.4V of DC when amplified. So my question is, how much of the 15.4V goes into my headphones if I don't have the volume turned up very much?

Don't forget you have the potentiometer before the opamp to limit the input voltage. In order to get maximum gain, you'll need to turn the volume knob all the way up (that's where you get the 15.4V). Since most of us don't turn the volume so high, you will get voltage b/w 1.4V and 15.4V, depends on how much you have turned the volume knob. Assuming the potentiometer works very linearly (some don't), you can probably divide the voltage difference over each degree of turn. Well, I think in theory anyway.

Quote:

Originally Posted by upstateguy /img/forum/go_quote.gif - I find that even with my HD650s, I listen at around 70% of full volume from the Fuze's HPO. This is loud enough for all my general listening. As you know, I also have a Griffin dock. Since the LO volume is equal to 100% volume (on the "Hi" setting) from the HPO and I am only using 70% of the volume which the dock delivers to the amplifier, I end up using the amplifier as an attenuator. So my question is, is there any advantage to using the amp as an attenuator or am I better off just using 70% of the HPO?

Lets toss the discussion on whether LO and HO is the same or not plus the sound quality of Griffin dock aside first, and assume LO from Griffin dock sounds the same as HO, then the question can be simply turned into whether adding an amp help HD650 performs better. For that question, I think Uncle Erik has written a very informative reply that is better than what I can explain myself. I think we can safely conclude that an amp is more than just an attenuator.

Unless there is synergy issue (i.e. bright amp + bright headphone = harsh sound), I don't really know any technical disadvantage of adding an amp. By disregarding the source and synergy (assuming perfect), the only technical issue is, how much will the headphone benefits more an amp. Some headphones does benefit a lot but some don't - of course, it is still a human judgment in the end. Great improvement can be nothing to deaf ears while minor touch up can be all that is asked for on the ears of very critical listener.