iMod iRiver, DC problem

[nelsonvandal]

A long time ago I "imodded" my IHP120 - BlackGate HiQ 47uF caps direct from line out. I got quite a lot of DC on the output, and that scared me enough to solder the tantalums back in place. Then I discovered that there is DC on the line out with the original caps as well. The DC disappears after I connect line out to an amp or phone, probably just discharging the caps. I never had the energy to redo the mod, and since the DC scared me to not plug in my expensive phone (HD650), and since all my amps are DC-coupled, I never got the chance to evaluate it.

Has anyone else done this? What did you experience? Should I redo the mod, is it worth the effort?

[nelsonvandal]

Ha! I did this again. Now I'm listening to the sound of BlackGates. Just as I thought, the DC-offset disappears when line-out is connected to an amp.

BlackGates have this rumour, that they need several hundred hours of burn in time. So I'll let them burn in, and then I'll post some impressions. This is not a very hard-to-do mod.

[d.phens]

Could you please post a guid to iModding (if nothing blows up )?
Actually is it worth that?
Isn't the line-out on IHP1xx series a 'true' lineout?

As I see you just swapped the caps, did you change or add anything else?
Thanks!

[nelsonvandal]

It's a "true" line out. Just compare it to an ordinary pre-amp. The output from the pre-amp is also affected by the volume, balance, bass and treble control. I can't see why people don't think this is a true line out . Line out as opposed to headphones out is a high impedance low current output. It's not intended to drive headphones, but it plays my 300 Ohm HD650 really well. If you connect a 32 Ohm headphone, the output capacitor will decrease bass from 110 Hz with 6 dB/octave (first order high pass filter) and there isn't enough current so the sound will be distorted as well. Headphones out is a buffered output with low impedance and high current. The problem is that this buffer is noisy and doesn't sound good.

The only thing I did was change the caps. I let the resistors be. There's nothing more than a resistor and a capacitor in series with the DAC's output, as opposed to iPod which seems to have separate DAC and sound processor chips. As I said BlackGates are notorius for their long burn in time. At first the sound was more two dimensional than before and the treble was harsh, but now after some hours (maybe 30) it's more 3D again and the treble is sweeter. I think the bass is fuller and punchier (it was from the start). These capacitors are claimed to need several hundred hours to burn in properly. I'll give a more detailed report later. I've made a "dummy load", so I don't have to plug in the headphones while burning in.

If you want, I can take it appart and take pictures of it. I used the schematic and pictures publiced at Rockbox.org
http://www.rockbox.org/twiki/pub/Mai...tics/audio.pdf
http://www.rockbox.org/iriver/back.jpg


I forgot to tell you, unless you have a very good headphone amp and very good headphones, I would not recommend this mod.

... and use high-res coding like FLAC or OGG (at high bit rate).

Here are some pictures and a "guide":
And yes the HD is changed to a 30 GB (the original was killed when I dropped the player while it was loading) and the battery is also changed.
1. Remove 4 screws from the bottom cover, 4 from the top and 1 from each side, all in all 10.
2. Remove the top and bottom and unfold the DAP like a book.
3. Remove the hard drive.
4. Find the two caps C33 and C34, unsolder them carefully (they seem to be glued to the board, so this was a bit tricky the first time.
5. Cut wires of appropriate length (I used PTFE insulated silver plated copper gauge 26), two for each cap and solder them to the caps, and then solder them to the board. The caps are non polarized, so you don't have to worry about positive or negative lead. A you can see, I used heat shrink on the caps to prevent shorting.
6. The 6.3 V 47 uF Black Gate NX Hi-Q fits perfectly above the line in/out jacks.
7. Put the HD back in place...

A more elegant, but much harder, way of doing this would be to connect the wires directly to the line out jack, but I don't think that an extra 5 cm wire degrades the sound too much. The cables should be twisted, but I didn't want the extra tension on the PCB (PTFE cables are kind of stiff).

I didn't dare do anything with the resistors. I suppose they are there for a reason. The resistors are very small, so it would be hell to put them back in place after removing them. I don't think a resistor degrades the sound as a capacitor do.

Unless you like taking risks in life, you shouldn't do this if you're not comfortable with soldering SMD parts (I wasn't the first time but did it anyway. I'm a curious kind).

[nelsonvandal]

I think it has run about 100 - 200 hours now with the new caps. I've done no A-B listening tests of course, and there are no dramatic changes to the sound, so I can't really say that I'm certain about what I'm saying.

I'm almost certain that the bass is fuller and has more kick to it. I'm almost certain that those Black Gates aren't natural. They seem to add a "shining" and warm sonic signature. A little dark, a little "tube amp-like". I think there's a lack of energy in the highest high. I think it's a bit more enjoyable now, a bit more "musical" and involving. I think the sound is less harsh.

The mod only affect the line out, to be used with an amp. The headphones out is still as crappy.

[MoAv]

Wow, this is new kind of mod, getting better caps for your H1xx.
Good job Nelson !
Do you think there's an option on replacing the caps for the head out ?
I'm using an H595 and usually without an amp.

[nelsonvandal]

Originally Posted by MoAv

Wow, this is new kind of mod, getting better caps for your H1xx.
Good job Nelson !
Do you think there's an option on replacing the caps for the head out ?
I'm using an H595 and usually without an amp.

No the headphone out goes straigt from the DAC/amp chip to the jack. Not really true, it passes an inductance. I've bypassed this inductance, but the sound is absolute the same. There is no capacitor on the headphone out. The problem is the built in headphone amp is not as good as it should have been. Many reports says that the newer DAP's like Cowon A2, Zune etc has a better headphone output. I still think line out from iRiver is very good though.

If you want better sound from your Hxx, you have to use line out to a dedicated headphone amp, or... there's the iBasso D1 with built in DAC (of great quality) and optical in. There are some reviews of it on Head-Fi.org http://www.head-fi.org/forums/showthread.php?t=253987, but no review on how the DAC sounds compared to iRivers DAC. I'm very temted getting one myself.

[MoAv]

Ok I see, actually the DAC you suggested fits my needs and the pocket.
I think that's going to be my first portable DAC.

Thanks for the info.

MoAv