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Review and Measurements of Violectric HPA V281 HP Amp
- Thread starter amirm
- Start date
Oh sad. Found this. There used to be jumper for dc coupling in v200 and some other models.
So...no jumper for dc couple.
Btw for those who don't know violectric = lke people.
So...no jumper for dc couple.
Btw for those who don't know violectric = lke people.
restorer-john
Grand Contributor
For $2500, I want a week in that little fishing shack in the foreground, a 24/7 French Maid and a personal chef.
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- Nov 22, 2018
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restorer-john
Grand Contributor
DC coupling in a headphone amplifier, without rapid DC protection circuitry is foolish. With the obviously high rails (>50V), delicate headphones could be vaporized with assymetric input transients etc.
Not only that, any offset, however small will be amplified by a DC coupled connected amplifier when used as a preamplifier and either a) trip the amplifier's DC protector if it has one or b) cause significant voice coil displacement in any connected speakers.
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That's not completely true.(Or you are talking about something different.)
You can use precision opamp to control the offset. And adding DC protection at the output.
On this instance, AC coupling is added in the middle of signal path instead of output. So no protection for output either. It only protects from the source dc component. And the most amount of offset is from the discrete output stage instead of anywhere else. You can argue using not very good opamp(tho it's opa2227 here) and adding lots of gain can cause offset.
Also DC won't cause coil displacement unless there's constantly increasing DC level. Coil is inherently AC coupled. With any given DC offset, it will eventually settled back to the center. Coil heating is a different story.
One extra point, even when implementing DC blocking circuit, one would design in such way that it doesn't hurt frequency response at 20hz. Merely 10k and 2.2uF will give about 0.5db loss at 20hz.
restorer-john
Grand Contributor
Ah, no. DC causes a speaker VC to shift and stay in that slightly offset position until the DC is removed. (or the VC overheats and burns out)
As for the amplifier concerned, if the output stage is DC coupled to the headphones, there should be a DC protection circuit and relay, as it clearly is running very high voltage rails (>50V). (Do the math on the output values and loads posted above). Likely in a balanced bridge type arrangement with perhaps a single supply rail so the net offset is zero. It's unlikely they'd be running split +/-60V rails as that would be insanity in a headphone amplifier.
Using inter-stage coupling capacitors is perfectly fine, and unless calculated incorrectly, they should not affect any legitimate musical content. Consider people who may use one of these alongside a phono preamplifier and the last thing you would want is infrasonic rumble/arm resonances being amplified- a very quick way to destroy expensive headphones.
Anyway, this is conjecture on my part, I haven't seen one or inside one.
restorer-john
Grand Contributor
And you need to consider the following stage impedance, especially if it varies (pot), or connected load...
-2db at 20hz is a bit too much for an amplifier tbh.Ah, no. DC causes a speaker VC to shift and stay in that slightly offset position until the DC is removed. (or the VC overheats and burns out)
As for the amplifier concerned, if the output stage is DC coupled to the headphones, there should be a DC protection circuit and relay, as it clearly is running very high voltage rails (>50V). (Do the math on the output values and loads posted above). Likely in a balanced bridge type arrangement with perhaps a single supply rail so the net offset is zero. It's unlikely they'd be running split +/-60V rails as that would be insanity in a headphone amplifier.
View attachment 35637
Using inter-stage coupling capacitors is perfectly fine, and unless calculated incorrectly, they should not affect any legitimate musical content. Consider people who may use one of these alongside a phono preamplifier and the last thing you would want is infrasonic rumble/arm resonances being amplified- a very quick way to destroy expensive headphones.
Anyway, this is conjecture on my part, I haven't seen one or inside one.
Pot can be used as the R in the rc circuit. In Violectric amps it seems to be ALPS 100k ones. So idk why is that -2db at 20hz.
restorer-john
Grand Contributor
I agree. Especially if that is a 200K ohm load out the line out jacks. (as per the dashboard).
The AP's AC coupling is flat to <10Hz I believe, and the FR sweep would surely be using DC coupling.
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OP
- Thread Starter
- #32
It is. Indeed to make sure nothing was wrong in my setup, I put the AP in loopback mode and it was solid flat.
OP
- Thread Starter
- #33
That is a very good find. They should fix the specs to reflect that. It sure caused me to lose some time testing and retest to see what is going on.
OP
- Thread Starter
- #34
FYI, the owner had lifted the ground and hence the reason there are some mains components in my measurements even when using XLR.
OP
- Thread Starter
- #36
The perfect channel match is an advantage over Atom or THX.
IIRC this product is Made In Germany. You know, where the working class usually get by with just one job, have decent hours, enjoy their work and company of their colleagues, the companies they work for PAYS them on holiday leave (4 weeks a year) and last I heard and parental leave was paid for 14 weeks?
This is made by Lake People. It’s bulletproof and I’d happily have this in my studio knowing that it’ll probably last (and be supported) forever. Lake People have been making dedicated headphones amp, almost as long at Headroom, if memory serves me correctly. Like decades. They were making headphones amps for the studio long and before consumers realised they would benefit from headphones amps.
I find it curious that we all seem to want excellent products that are cheap, and turn a blind eye when it’s made in China. You know the place where workers have no say or rights; kids spend their school holidays “interning” (ie. assembling electronics) at the mega-factory-town
https://www.trtworld.com/life/foxconn-admits-overtime-by-student-interns-in-china-factory-28898
When there are no manufacturing jobs left in America (or other developed/Western country here) because all the corporate bosses have spent the last 3-4 decades moving production to places with the cheapest labour, what are we going to do? But as consumers did we ever reap the manufacturing cost savings?
Now in 2019 the world has witnessed Chinese companies (=groups of people) buying Western companies, land holdings, real estate...
Bravo on the Lake People/Violectric product!
I’m not holding my breath waiting for another product that measures so well and provides such utility.
And yes, having a HPF on a headphone amp is a wise design decision because you can’t hear those frequencies from headphones anyway. When you have that much power on tap it’s better to stop subsonics getting through and ruining your teeny 2” drivers...
This is made by Lake People. It’s bulletproof and I’d happily have this in my studio knowing that it’ll probably last (and be supported) forever. Lake People have been making dedicated headphones amp, almost as long at Headroom, if memory serves me correctly. Like decades. They were making headphones amps for the studio long and before consumers realised they would benefit from headphones amps.
I find it curious that we all seem to want excellent products that are cheap, and turn a blind eye when it’s made in China. You know the place where workers have no say or rights; kids spend their school holidays “interning” (ie. assembling electronics) at the mega-factory-town
https://www.trtworld.com/life/foxconn-admits-overtime-by-student-interns-in-china-factory-28898
When there are no manufacturing jobs left in America (or other developed/Western country here) because all the corporate bosses have spent the last 3-4 decades moving production to places with the cheapest labour, what are we going to do? But as consumers did we ever reap the manufacturing cost savings?
Now in 2019 the world has witnessed Chinese companies (=groups of people) buying Western companies, land holdings, real estate...
Bravo on the Lake People/Violectric product!
I’m not holding my breath waiting for another product that measures so well and provides such utility.
And yes, having a HPF on a headphone amp is a wise design decision because you can’t hear those frequencies from headphones anyway. When you have that much power on tap it’s better to stop subsonics getting through and ruining your teeny 2” drivers...
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I think that this product costs what it does because Lake People know that there is an audiophile market which is convinced that more expensive = better and is willing to pay for exclusive products. I don't blame them for exploiting that market as they are in it to make money. If it was just about being made in Germany then they would not be able to offer nicely made amplifiers at sensible prices under the Lake People brand (which they do).
Every damn audio amplifier should have DC elimination in the output, eg. capacitor-coupled!
What's the point of risking to damage your precious speakers or headphones with thumps and subsonic noise. Ability to pump membranes up and down to the limit does nothing good for sound quality Even some digital releases have lots of noise down there, not to mention vinyl playback.
What's the point of risking to damage your precious speakers or headphones with thumps and subsonic noise. Ability to pump membranes up and down to the limit does nothing good for sound quality Even some digital releases have lots of noise down there, not to mention vinyl playback.
filo97s
Active Member
a review so long awaited, thanks!
Still, there's no reason to spend more than 100$ required for the atom. Unless you really want balanced in/outs, unnecessary however unless you have ground problems or very long cables.
Still, there's no reason to spend more than 100$ required for the atom. Unless you really want balanced in/outs, unnecessary however unless you have ground problems or very long cables.
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