[Prmedc]

So I've just recently started to investigate high(er) end headphones over the last month or so.  I decided to plug my UE TF10 into my Onkyo C-7030 headphone output and see what they sounded like with the direct CD connection.

Unfortunately, this produced an "underwater" sound on every type of music.  I used my small portables (Sennheiser PX200-II) and the sound improved but was still indistinct compared to the same (FLAC) music from a cell phone output. The TF10's usually blow the Sennheisers away making it more unusual.  I recalled some articles I had read on output impedance and determined that the output impedance of the CD player headphone was around 340 ohms. Which would explain my decreased sound quality. 
 
I have a 250 ohm DT990 on order along with the Onkyo TX-8050 which will be used to primarily drive some Paradigm monitors. I'd also like to use the 8050 to drive my DT990 for now.   I can't determine the output impedance of the 8050 headphone jack but I'm assuming it went to the same party as the C-7030.  From what I've read the output impedance would still be too high for nearly any "hi-fi" headphones.

Will the Onkyo output impedance work while driving a small headphone amp (think FiiO) which would basically just be used to fix the impedance problem?  Or do I need to forget that route and simply get an amp with RCA line inputs?  I would like to be able to use the 8050 with my headphones since I can stream FLAC, online radio, and listen to the CD player out of the one output. 
 
I'd also be open to modding the output circut if possible - I have some experience with SMD mods from my other hobby, amateur radio.
 
Thanks for any help.
 
Prmedc

 

[PurpleAngel]

 
Quote:

Originally Posted by Prmedc /img/forum/go_quote.gif
So I've just recently started to investigate high(er) end headphones over the last month or so.  I decided to plug my UE TF10 into my Onkyo C-7030 headphone output and see what they sounded like with the direct CD connection.
Unfortunately, this produced an "underwater" sound on every type of music.  I used my small portables (Sennheiser PX200-II) and the sound improved but was still indistinct compared to the same (FLAC) music from a cell phone output. The TF10's usually blow the Sennheisers away making it more unusual.  I recalled some articles I had read on output impedance and determined that the output impedance of the CD player headphone was around 340 ohms. Which would explain my decreased sound quality. 
I have a 250 ohm DT990 on order along with the Onkyo TX-8050 which will be used to primarily drive some Paradigm monitors. I'd also like to use the 8050 to drive my DT990 for now.   I can't determine the output impedance of the 8050 headphone jack but I'm assuming it went to the same party as the C-7030.  From what I've read the output impedance would still be too high for nearly any "hi-fi" headphones.
Will the Onkyo output impedance work while driving a small headphone amp (think FiiO) which would basically just be used to fix the impedance problem?  Or do I need to forget that route and simply get an amp with RCA line inputs?  I would like to be able to use the 8050 with my headphones since I can stream FLAC, online radio, and listen to the CD player out of the one output. 
I'd also be open to modding the output circut if possible - I have some experience with SMD mods from my other hobby, amateur radio.

 
I doubt your CD player headphone jack has an impedance of 340-Ohm, the highest I've ever heard is 100-Ohm impedance, my STX sound card has a 10-Ohm impedance, so 340-Ohm impedance sound funny to me.
 
I believe your cell phone is geared more for your TF 10s then the Onkyo.
 
So plug the DT990s into the Onkyo 8050 and see what happens, then go from there.
 

 

[RexAeterna]

is there schematics? i doubt as well it's anywhere near 340 ohms. it's not a receiver. i think it probably be somewhere of 0-120ohms more likely. i used use cd players stand alone before and sounded really good and clean with multiple headphones. i was amazed at when it even made my 600 ohm 240DF's sound insanely good and even had no issues with an older yamaha hp-1 ortho. it was some older 1990's jvc cd player though and i still have it. just never been using it recently.

 

[stv014]

Quote:

is there schematics?

 
Schematics are unfortunately very rarely released for any equipment that is less than a few decades old. If you want to know the output impedance of a device, ~99% of the time you have to measure it yourself (which is neither very hard, nor require expensive gear).

 

[BrownBear]

Well one thing you could do is get an RCA to 1/8" cable, so you could plug the outputs of the receiver into the Fiio. Beware though, it may not work, I tried going from the RCA from my CD player into the Fiio E5, and the amp couldn't handle that level of input. However, with the price of an E5, it might be worth your while to give that a shot.
 
Also, remember. The high output impedance thing is not really set in stone. What I mean is, 'technically' it may be too high, but what matters is the sound. Do you like it? If so, why bother changing? I'm just kind of rambling to prove a point haha. You got some high impedance headphones here, they should be fine out of a receiver jack, IMO. Give it a chance is basically what I mean. I wouldn't think of it as a decrease in sound quality, but more, a different sound. The key is, if you don't like the sound that headphone jack gives you, then you might what to make a change.

 

[PurpleAngel]

You can get a single tube headphone amplifier for around $60-$80 off eBay, ships from China, takes ten days.
Just run some RCAs from the Onkyo to the tube amp.
The website Rockgrotto forum has a headphone amplifier subsection, guys there like these little tube amps.