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WolfX700 Measurement of Topping A90 Headphone Amp
- Thread starter WolfX-700
- Start date
@JohnYang1997 this kind of performance but without any channel imbalance issues is what I need.
Will there be a product coming that meets this?
Like HPA4's headphone output.
Will there be a product coming that meets this?
Like HPA4's headphone output.
The good channel balance of the pot PLUS the attenuation gain setting allows you experience free from channel imbalance in practice sense.
There's a preamp that has it which can be used with A90 or power amp.
Idk. I think not.
Looks more promising than ever! But for audiofool question: during testing did you use some demanding headphones like the audeze or Hifiman planars and compare to other more distorted competitor products? Interesting about how subjective experience actually get as I personally guess the extra detail in the highs and no roll off likely make it sounder brighter when first used?
Very minimal difference can be experienced comparing to SP200. SP200 actually is the one that sounds slightly "brighter" and "energetic" during two blind tests. But I think it's due to noise. I don't expect it to actually sound that much better. But when you have something like this you feel good while you listen and you don't worry about it when paring with headphones. And most importantly it's mainly for technical superiority not so much in audible territory. But still better is better, competition is competition.
Yea, can’t agree more on that, back on the days when I purchased the auralic my main thing was the op amp based units back then don’t have enough power for the Hifiman claimed power requirement and so that’s why I opt for the auralic. And may I ask two more questions:
1) is it class AB operation?
2) I saw in dx7 pro you did have rollable op amp sockets, will this be the same? Somehow I feel like if a product is so competently designed I prefer non rollable stuffs
Right, really thanks for the information.
sidetrack a bit more, do you think the ic chip outputting such high current in class ab, will it operate too hot inside and potentially lowers the life of the unit ? Or need some extensive heat sinking to be safe
sidetrack a bit more, do you think the ic chip outputting such high current in class ab, will it operate too hot inside and potentially lowers the life of the unit ? Or need some extensive heat sinking to be safe
Maybe. We have installed large heatsink on the chip for cooling. The first surge of heat will be sinked by the PCB copper area. The mid term heat is sinked by the heatsink which lowers the thermal resistance to ambient hence reduce the rising speed of the die temperature. For the long term, the chassis is not vented so it's not for long term heavy loading.
In all THX based headphone amps, there's no other heatsinking other than using the PCB copper area. It should be enough for regular use but the chip can get hot under heavy load condition like review testings. We better be safe right?
Sure for the be safe part, and to be honest for most users who are willing to spend big money into headphone listening they likely will listen for long sections once a while for hours, and some will live in hot tropical areas with ambient temperature around 30 degrees C or higher, so better be safe for that. For that part maybe is where the discrete design champs as they inherently have much larger area for heat dissipation
Not necessarily. If one puts design consideration into it, there's no issue. Discrete operates at much much higher idle current tho the heat is distributed to each discrete component it's not an ideal solution. The total amount of heat that's generated is much higher. The chip designers know how to design a chip so if there's all the protection and still allows you to operate at such condition, it's allowed. One exception is ad8397 which we need to be much careful and need much more testing to ensure not to over current and kill the chip due to lack of protection circuit, that's a different story. And one can always parallel chips to get more current and distribute heat better.
Ahh ok. So do electrostatic headphones actually need more power to drive or is it just a matter of voltage? What does it mean when stax says their gear has 580V bias voltage or that maximum output voltage is 340Vrms ?
Electrostatic headphones are very high voltage and very low current.
An electrostatic driver is made up of two perforated electrodes, or stators, with a diaphragm held in between. Unlike a normal headphone there are no magnets and none of these components have a permanent magnetic or electric field.
The bias voltage is a static voltage applied to the diaphragm so that the varying voltage applied to the stators can move it back and forth to create sound. The output voltage it the difference in voltage the amplifier can apply across the stators.
The necessary bias voltage is more or less a function of the spacing between the stators and the diaphragm. All Stax headphones made for the last several decades use 580V bias. It was called "Pro" when first introduced to differentiate it from the older and retroactively named "Normal" bias which I believe is 230V. For Stax gear, normal bias headphones and amp outputs have 6 pin plugs and sockets while pro bias (everything you can buy new nowdays) is 5 pin.
Other manufacturers who have made electrostatic headphones and amps compatible with 580V Stax pro bias have also used the same 5 pin plugs and sockets.
shadymilkman
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- Apr 2, 2020
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Registered to say that I am really excited to get my hands on this amp.. (literally just bought a Monolith 887 a couple weeks ago) and was going to pair it with the D90... @JohnYang1997 your involvement here and willingness to respond has resonated with me. between the aesthetics and measurements this is what I will be looking forward to. The lack of 4.4mm on the monolith was a bummer my old JH16s needed a home but I compromised, so thank you and your team for that choice.
Welcome to ASR!
I had a DX7s but upgraded to a DX7 Pro when I found a used one at a price I could not pass up. I have Beyerdynamic DT1990 Pros that I like but after hearing the Audeze LCD-X at the recent Florida Audio Expo I've been watching for a pair at the right price. I just bought a pair of LCD-3 as they were at a price I could not pass up. They arrive on Wednesday. I can't wait to see how they sound on my DX7 Pro. The D90/A90 combo is next on my upgrade list.
Martin
Martin
Ha! Too funny! I currently have a DX7s as well (and a D50s on the way)...and a V1 Dx3 Pro (love that one for iems). Thought I'd try to go for the DX7 Pro to see how the sindle ended headphone out sounds compared to the Dx7s and Dx3 Pro. Currently I prefer the Dx3 Pro for my iems (Fiio FA7 and FH7) a bit more than the Dx7s...I really want to try the D90/A90 combo at some point. Haven't tried my EL8c's on them yet...
Thanks
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