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In Reply to: RE: Hafler HA-75 posted by Dawnrazor on August 08, 2019 at 19:44:45
I am surprised it doesn't have a higher voltage out. Discrete circuitry is nice and an external power supply would help to have a quieter circuitry.
iBasso DX220, DX120. Focal Utopia and Stellia. iBasso SR1. Mr. Speakers, Ether II, Voce stats. Manley, Absolute HPamp. LTA MZ3, Z10e electrostatic amp. Various other headphones, amps, cables etc.
Follow Ups:
From the Master Switch review:
The amp takes any headphone between 8 and 400 ohm impedance, which, these days, means just about any pair on the market. One thing to be aware of is that this amp, if you let it, can get extremely loud - especially when you are fiddling with the Feedback control. You need to be careful that you don't blow out your headphones - or your own ears.
Cutting razor sounding violins
Knowing the power out is more helpful. There are some planars that do best with 3 to 5 watts into around 50 ohms. I din't understand why they don't post the power out.
iBasso DX220, DX120. Focal Utopia and Stellia. iBasso SR1. Mr. Speakers, Ether II, Voce stats. Manley, Absolute HPamp. LTA MZ3, Z10e electrostatic amp. Various other headphones, amps, cables etc.
> I don't understand why they don't post the power out.
They specify the output voltage to be 5-V RMS maximum. Why can't you simply calculate the power from that.
Power = Voltage 2 / Resistance
If you're using 8-ohm headphones, the maximum power would be:
5 2 / 8 = 3.125-watts
If you're using 400-ohm headphones, the maximum power would be:
5 2 / 400 = 0.0625-watts
Therefore, the maximum power out will vary between 0.0625-watts and 3.125-watts depending on the type of headphones you use.
Best regards,
John Elison
Thanks for the marh
The amp has an impedence selectorr that lets you vary the impedence between 20ohms and 400 ohms. Does that affect the math? And if not what does that feature do??
Cutting razor sounding violins
Good question! I'd need to see a schematic of the headphone amplifier to find out what's going on with the impedance selector.
On the other hand, if the 5-volts output is dropped across the internal impedance and the headphone impedance, it would reduce the maximum power values I calculated in my previous post. If that were the case, then the maximum power delivered to any headphone would be 25% of the values previously calculated when the selector switch is set to match the headphone impedance. The maximum power delivered to any given headphone would be as follows:
[5 / (selector impedance + headphone impedance)] 2 x headphone impedance = power
For example, suppose you had headphones with 20-ohms impedance and the selector switch is set to 20-ohms. The power would be as follows:
[5 / (20 + 20)] 2 x 20 = 0.3125-watts
If you had an 8-ohm headphone, the maximum power that could be delivered to that headphone would be:
[5 / (20 + 8)] 2 x 8 = 0.2551-watts
The maximum power delivered to any headphone would occur when the impedance selector switch is set to the same value as the headphone impedance.
Best regards,
John Elison
Hello, I am new to this forum (found it 5 minutes ago). I have been searching for info and reviews on this amp everywhere. I even emailed the company two times and got no response. I really appreciate the estimated power calculations from John Elison. If the calculations by John are even ballpark, this amp will cover my needs. Does anyone here have any ear time with this amp? Maybe with some power hungry headphones? Some first hand feedback is all I am looking for and I will press the 'order' button! Thank you.
I have had it say 6months or more. Its fabulous. The VOX and Matrix feature is a godsend for me. Though I have easy to drive planar cans and set the impdence knob to 50ohm. 50ohm 90+db cans here. Never get more than 9-10 oclock on the vc.
I doubt it makes a difference but I run one output to the right ear and the other to the left ear. Just made up some cables to tap into the right output.
I think you will be fine. Its a heck of an amp. There are some Youtube reviews or at least one. You might ask in the comments.
FWIW I would recommend this amp to a friend. Even the kind that would hassle me everday if it didn't work out. My only quibble with it is that it only has one set of balanced ins. But find me any amp in its price range that has 2 pairs of xlr inputs...never seen that. Its a winner.
Cut to razor sounding violins
Thank you for the quick reply and the good feedback. I am gonna start shopping for an HA75 now.
I dont have a schematic, but here is a pict. The left top knob is the impedance setting.
Cutting razor sounding violins
Yeah I get it. FWIW I have a 50 OHM planar and it sounds amazing. They are right at least about the loudness. I am at half on the pre and say 40% on the amp and its too loud. Bass is the best I have heard from these cans...
Cutting razor sounding violins
the Abyss 1266. Some planars are easier to drive, and that is why power out needs to be stated, so there is a basic understanding what it will do at the beginning. Odd they don't have a power rating in the specs.
iBasso DX220, DX120. Focal Utopia and Stellia. iBasso SR1. Mr. Speakers, Ether II, Voce stats. Manley, Absolute HPamp. LTA MZ3, Z10e electrostatic amp. Various other headphones, amps, cables etc.
Sure man send me a pair and I will test for you
Cutting razor sounding violins
but really, they should post such a simple thing for a home amp. They do for speakers, why on earth not for a headphone amp. Not trying to harp on it but wouldn't buy something blind like that without knowing some some basic specs like power into load etc.
iBasso DX220, DX120. Focal Utopia and Stellia. iBasso SR1. Mr. Speakers, Ether II, Voce stats. Manley, Absolute HPamp. LTA MZ3, Z10e electrostatic amp. Various other headphones, amps, cables etc.
Yeah its supposed to be used for studios and has an impedance switch up to 400Ohms. My cans are an easy drive and it has plenty of drive.
Lol there is a whole page in the manual about how powerful it is and can cause hearing damage...
Cutting razor sounding violins
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