Hello, yes this post was in regards to the ASGARD SS amp. Someone asked if when turning off the amp was it normal to see or hear a mechanical driver excursion.
Jason one of the co-founders replied several times, the results from the moderator at headfi.com found this:
The diaphragm of my K-701 deformed similarly to the video in the thread. I measured the right channel only.
I used one of my Fluke meters set to trap min & max potentials. After visually testing the K701 diaphragm movement, I measured electrically using a pair of LCD-2s, so the load was 50 ohms resistive, again, right channel only.
turn off
-2.2 VDC peak
0.584 VAC peak
turn on
1.112vdc peak
0.332vac peak
I repeated measurements several times to verify results.
The voltage measurements represent just under 100mW of power for less than 0.25 seconds. That's not enough energy to harm any full size headphone I know, but I wouldn't recommend this with sensitive IEM's
Jason replied as well with this:
Hey all,
I jumped on this and did our own measurements after KW did his. And yes, I can confirm: I was mistaken about the magnitude of the turn-off transient. That's what I get for looking at engineering notebooks over the weekend, rather than going into the office and actually testing. Our peak was about 1.7V at 32 ohms, or about 90 mW.
We have never had anyone complain about driver failure or sonic degradation of their headphones with the Asgard amp since we started shipping. We believe it is generally safe for most headphones. We do not recommend any of our amps with IEMs, and have always stated this.
However, we do understand if you're concerned. So here's what we'll do:
1. We'll add a foreward to the owner's manual recommending to connect sensitive headphones after turning the amp on, and unplugging the headphones before turning the amp off. We'll also add an addendum to the warranty to cover shipping, parts, and labor for any headphone jack failures during the warranty period, to address any possible wear and tear on the jack.
2. We will investigate adding a relay mute to the Asgard, despite my misgivings about relay contacts.
And, to address any other concerns our owners might have:
3. If you purchased an Asgard from us at any time, from June 1, 2010 to the current date, and feel uncomfortable about its performance, contact us and we will take your Asgard back and offer you a full refund of the retail price.
All the best,
Jason
Upon adding this relay many folks were upset by adding this relay over concerns of it affecting the sonic qualities of the amp and realy degradation over time...guess you cant please all the people all the time....now you klnow the rest of the story..
I was an owner of this amp Asgard and had the same cans, AKG702's that the person that started this thread for a year or so. I never had any issues with this combination.
The Lyr has a relay in it.
The important thing when your using these amps and many others is there is an order of powering up and powering down things...I dont care how well your stuff is built and designed...things fail.
I always make sure the volume is all the way down, turn on the amp, wait a minute or so, then plug in the cans...quque up a song...and then slowly trun up the volume and if I dont hear anything...I STOP and figure out what isnt on or selected....
When shutting down the volume is all the way down, I remove the cans. Then and only then do I power down the amp...
Its just smart and good practice.
All the best
Alex
