Impedance ??

[cjacek]

Hi,

I'm currently shopping for "vintage" headphones for my TASCAM 244. I know that impedance is important 'cause presently there's not enough "juice" from the 244 to power my AKG 600 ohm cans. I know the lower the better ohm but what is the max ohm I can buy and still get sufficient loudness, without turning the vol all the way to the right ? I was looking at the Koss 4aa but they're 250 ohm and then there are others from pioneer, from the 70's, like the se-20, se-30, se-305, se-405 etc ... but sometimes the auctions don't provide details re impedance. Ok, I guess my question is .. What would be the MAX impedance I should be looking at to get nice sufficient volume on my 244 without turning up the volume all the way ? Thanks in advance for your replies.

Daniel

 

[The Ghost of FM]

Any decent closed cup headphone from 32 to a 200 ohm load should be able to provide healthy output from the Portastudio's headphone jack.

The efficiency spec of the headphone is probably even more important then the impedance spec though. Look for numbers of 94db @1milliwatt and up for good sound pressure.

I wouldn't worry much about turning up the phones to 10 though. The amp in there is moderately clean even at full output.

Cheers!

 

[cjacek]

Any decent closed cup headphone from 32 to a 200 ohm load should be able to provide healthy output from the Portastudio's headphone jack.

The efficiency spec of the headphone is probably even more important then the impedance spec though. Look for numbers of 94db @1milliwatt and up for good sound pressure.

I wouldn't worry much about turning up the phones to 10 though. The amp in there is moderately clean even at full output.

Cheers!

Thanks Ghost! How about these specs ? It's 250 and not 200 ohms as your max though.

stereophone specifications

Frequency Response: 10-25,000 Hz
Impedance: 250 ohms
Weight: 21.0 oz.
Sensitivity: 95dB SPL/1mW
Distortion: <0.1%
Ear Cushions:
Cord: Coiled, Single Entry, 10ft
Plug: 6.4 mm

 

[cjacek]

The efficiency spec of the headphone is probably even more important then the impedance spec though.

Why may be this more important ?

Daniel

 

[jrosenstein]

the impedance affects how much power gets transferred to the headphone. the efficiency/sensitivity determines what volume that power translates to.

 

[The Ghost of FM]

the impedance affects how much power gets transferred to the headphone. the efficiency/sensitivity determines what volume that power translates to.

Agreed.

Make sure they are closed cup! Otherwise, the leakage will bleed into your overdub.

 

[cjacek]

Ok, this makes sense now 'cause even though my AKG's are at 600 ohms, they have a sensitivity of only 88 dB SPL/mW. If they were 95 db then I'd assume they'd get a bit louder even with the same ohm setting ? So the headphones that I'm interested are 250 ohms and have 95 db sensitivity and I assume from that they will be louder at lower vol settings than my akg's. Right ? So what would the different numbers for each headphone translate to when we're talking about volume ? If each headphone is plugged into a portastudio (244 in my case) what would the difference in overall volume be like ? Would the diffence be 20% or 30 or 50% etc .. ? I know it would depend on other factors but could you give an estimate ? Are the above specs significantly different for each headphone ? Ok, lets say we are talking about the same built headphones BUT headphone "A" is 250 ohm/95 dB SPL/mW and headphone "B" is 600 ohm/88 dB SPL/mW. Which one would be easier to "drive" ? Are these differences siginificant ?

Thanks again for your help,

Daniel

 

[The Ghost of FM]

The headphone you described as "A" should play at least twice as loud as your AKG's because it is more efficient and is allowing more power to flow from the headphone amp.

The higher the impedance, the more you are choking the amp so, a lower impedance allows more of the power to flow. That coupled with the better natural efficiency specs means you can now easily go deaf if you are not careful!

As a 42 year old rock and roller who has diminished hearing because of exposure to extreme sound volume while playing and recording, I can only echo a famous saying to you;

Be careful what you wish for!

Cheers!

 

[cjacek]

The headphone you described as "A" should play at least twice as loud as your AKG's because it is more efficient and is allowing more power to flow from the headphone amp.

The higher the impedance, the more you are choking the amp so, a lower impedance allows more of the power to flow. That coupled with the better natural efficiency specs means you can now easily go deaf if you are not careful!

As a 42 year old rock and roller who has diminished hearing because of exposure to extreme sound volume while playing and recording, I can only echo a famous saying to you;

Be careful what you wish for!

Cheers!

OK! I will .. Thank you

Daniel