as the title states, i havent been able to find a clear answer on if Planars are affected by a high output impedance, i do know that dynamic can be affected greatly. but im going assume since planars have a flat response to impedance that they are unaffected by output impedances??
-
Welcome to ASR. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!
are planars affected by output impedance? unable to find clear answer
- Thread starter birb
- Start date
The frequency response is unaffected by a high output impedance if the planar has a flat impedance curve. But if the output impedance is high you lose output power, because more power is burned in the amp than delivered to the planar. A rule of thumb is to have the output impedance not higher than 10% of the lowest impedance of the planar.
- Joined
- Mar 1, 2016
- Messages
- 1,057
- Likes
- 2,263
I think this is about damping or better damping ratio.
A high ratio is recommended (10 as a minimum) but how does it work out?
If you have a driver with a constant impedance (planar), you have a constant damping ratio.
If you have a driver with a varying impedance (dynamic), you have a varying damping ratio.
Don't think that is important.
What I can imagine is that if you have a driver with a high unsprung mass (moving coil) damping is more important compared with a driver with a low unsprung mass (planar)
A high ratio is recommended (10 as a minimum) but how does it work out?
If you have a driver with a constant impedance (planar), you have a constant damping ratio.
If you have a driver with a varying impedance (dynamic), you have a varying damping ratio.
Don't think that is important.
What I can imagine is that if you have a driver with a high unsprung mass (moving coil) damping is more important compared with a driver with a low unsprung mass (planar)
- Thread Starter
- #4
thanks
I think you can think of it simply that the output impedance effects the level of output you get from the headphone, depending on the headphone's impedance .
With a planar, the headphone impedance is constant, therefore the response is affected by the output impedance the same across the frequency range.
With a dynamic, the coil, magnet and suspension interaction is more complex and more frequency dependent. So some parts of the response will change in level more than others .. i.e the frequency response changes and it therefore sounds different.
With a planar, the headphone impedance is constant, therefore the response is affected by the output impedance the same across the frequency range.
With a dynamic, the coil, magnet and suspension interaction is more complex and more frequency dependent. So some parts of the response will change in level more than others .. i.e the frequency response changes and it therefore sounds different.
For several years, I used the Audeze MM-500 powered straight from the headphone output of an Apogee Symphony (a $5,000 pro DAC, higher z) for my work. I tried switching to the Topping A50 III (very low z) recently, and the reduction in low-end distortion was obvious. Output impedance definitely matters a lot here.
- Thread Starter
- #7
my issue is i cant afford a nice headphone amp so im using a Realistic STA-2000 (awesome stsreo from 1977) that i got for free that has 1.5kohm series resistors for the headphone output. im using it to drive my Hifiman Edition XS
An electrostatic diaphragm is so light in mass and large in surface area that the air surrounding it will damp it pretty well. Magneplanar and similar distributed magnet/coil designs will have a bit more moving mass but will still have pretty good damping from surrounding air. This is lost on cone type designs due to their higher mass to area ratios. The cone type damping can be done through the back EMF in the voice-coil/magnet system, which opposes the coil's motion.
Correlation is not causation . If the Apogee is black and the Topping a silver box, then should it be concluded that the colour is important in how well it drives the headphone?
Of course not, and neither should we conclude the same about output impedance .
However, the output impedance can imply something about the intention of the headphone output design and what they think the intended customer wants from it.
High impedance outputs on studio equipment is intended for deliberately chosen, high impedance, dynamic headphones. If you look at studio headphones, the models often come in different impedence versions for this reason. High impedance helps with very long cable runs, daisy-chaining headphones outputs to more than one musician/engineer and also means the headphone is driven by voltage and not current, meaning the current draw does not effect the working of the equipment's other features, as a converter in the Apogee's case. Headphones outputs on this kind of gear is often for simply checking what is coming out the outputs - not for critical listening
High impedance is not designed for low impedance planar headphones as planars require current delivery and high output mpedance makes this much much harder to do .
The Topping on the other hand is designed to provide high current to drive planars, as well as a high enough voltage capability for dynamics too.
Meanwhile the Apogee is only designed to deliver a specific type of dynamic headphone (a high impedance one).
The power and type of power needed for a headphone depends on the headphones. The Apogee simply is not designed to be powerful enough to work well with everything, whereas the Topping basically is.
A 1.5k ohm resistance (not sure what the exact calculated output impedence is .. something similar) is very high compared to proper headphone amps of today.
It is a simple and cheap way to make a headphone output that works with the average home dynamic headphones of the 1970s .
The Hifiman XS is a modern planar that is almost the total opposite of common dynamics of the 70s .. You'll get the full range sound but I bet it cannot produce enough current to push the low end properly . That resistor converts all the current ro voltage. But don't remove it either - else you'll fry your headphones and burst your eardrums.
Just get a Topping L30 mk II - probably about $60 maximum on eBay. Use it with any line level output, e.g. Tape on the receiver.
Similar threads
