[Maniac]

Quote:

All right, thank you David.
 

Just a bit of trivia, do you know that it is actually hard to tell a 6x gain and a 3x gain amp apart?  Due to the way our ear hear things, we only register a moderate increase in volume when we double the output power, I know that in principle, but I was just testing a 6x custom order unit out a while back, and before I put it on the scope, I had a listen.  I was kinda surprised about how little difference the volume control's setting between the 6x and 3x model.   I actually thought I might have set it up wrong, but on a scope, it shows up just fine, with twice as much gain as the 3x model.
 
This is why I don't offer every integer step of the gain setting between 1 and 11, because it would not really help anyone by having that much gain option when your ear would have a hard time telling apart a 3x amp from a 4x amp.
 
 
Anyways, have fun.
 

 

[K3cT]

Haven't seen you around Head-Fi for a while David. I hope you're doing well.  
 
Do you plan to release any new products in the near future? 

 

[Maniac]

Quote:

Haven't seen you around Head-Fi for a while David. I hope you're doing well.  
 
Do you plan to release any new products in the near future? 

 
Thanks!  I used to "patrol" the forums, but as I get more and more involved in product development, I got less and less energy to surf the forums.  I kinda moved from customer relations to product development.

 
We are actually currently selling a new product in Taiwan, but due to the limited quantity and cosmetic flaw on the case, we decided to just selling this batch in Taiwan, and once this batch is done, we will have a replacement for it that is designed to be about a level or two above the current product.
 
What's the product? It's a mini-DAC with USB/Coax/Toslink input, RCA and a very powerful headphone out.  We are working on the new one at the moment, it will be made with aluminum case instead of the current chromed-ABS plastic.
 
 
One very interesting feature of our DAC's headphone amp will be that it does NOT use traditional volume pot for volume, it will be electronically controlled, which will make sure it is always balanced, sounds good and won't wear out very soon.  (those tiny/blocky volume pots in headphones can wear out really quickly, and it would be a drag to hear scratching noises every time you change the volume)
 
 
I'll let you guys know more once I got something to show.

 

[Tribbs]

Hi David,
I am seriously considering your HA-006 standard dynalo without stepped attenuator.
I would use it primarily with a Grado 325i (32Ω) and was wondering what gain setting (1,3,11) do you recommend? 
 

 

[Paul Clark]

Go with the 3x gain setting.  That is what David suggested to me with these Grado cans.
It's a great Gilmore amp for great Grado cans!

 

[Tribbs]

Quote:

Go with the 3x gain setting.  That is what David suggested to me with these Grado cans.
It's a great Gilmore amp for great Grado cans!

Yeap, that's the ticket, 3x gain.  Thanks!
 
Got my HA-006+ and man, this amp is sweet with my Grados.  I can finally enjoy what these headphones can offer.

 

[zyss]

Anyone experienced the 1x gain with anything? I have Senns 600, 650 and 800. Always like to have no more gain than necessary. And don't listen loud. My source has adequate output. Will unity gain be enough?
Another question. David wrote here somewhere in this thread that gain options are made by using resistors. Does this not mean that the actual  amplification is the same in all gain versions and the difference is due to attenuation by resistors? Remember asking David about this privately, but he assured me that the amplification is different in each case, if I understood him right.

 

[Maniac]

I'm sorry to say that HA-006+/++ series had come to an end, we simply run out stock on it.  Instead of ordering more parts to build HA-006++, we feel a redesign is in order to reduce the massive drain on man-hours (lots of wires = lots of hours).  However, instead of doing that, there's another headphone amp we want to have a go first.
 
 
It is HA-008 OTL tube headphone/pre-amp.
 
 

 
 
It is designed with a lot of old fashioned passive safety features, there is no active load/current source/sink, there is no fancy output auto zeroing, there is no fancy automatic adjustment, in fact, there is no adjustment at all.
 
We want this amp to work 20 years from now, and hopefully even longer.  To make that possible, we make sure we use simple parts that is guaranteed to be on the shelf of any electronics parts shop.  Resistors, capacitor, diodes.  The only IC we used is a 555 timer, which we feel is likely going to be with us for a long time to come.  So if this amp breaks down 15 years from now, you will be able to buy replacement parts from your local shop, and have it working in no time.
 
 
Now with the basics done, it is basically a OTL amp that sounds really good, and we did compare a few OTL headphone amp we could get our hands on.  The result is fairly encouraging.
 
For those who worry about noise:
This amp is very quiet, even sensitive headphones should work just fine.

For those who worry about power:
8 ohms = max power per channel   7.2mW ( 0.24V)
16 ohms = max power per channel  14.4mW ( 0.48V)
32 ohms = max power per channel  28.8mW ( 0.96V)
64 ohms = max power per channel  57.6mW ( 1.92V)
120 ohms = max power per channel 108.0mW ( 3.60V)
200 ohms = max power per channel 180.0mW ( 6.00V)
300 ohms = max power per channel 270.0mW ( 9.00V)
400 ohms = max power per channel 360.0mW (12.00V)
500 ohms = max power per channel 450.0mW (15.00V)
600 ohms = max power per channel 540.0mW (18.00V)
max theoretical  1466.7 ohms = max power per channel 1320mW (44.00V)
 
For those who worry about gain:
User selectable 3x/10x

For those who worry about tubes:
We use Russian 6N6P OTK tubes with gold plated grid for power tube, signal tube is 6N1P.  User can set it to use 6DJ8/6922/ECC88/CCA or compatible tubes via internal dip switches.
Replacement tubes are going to be available for $35 per set of 2 6N6P and 2 6N1P
 
 
And that's about it for now.
 

 

[lugnut]

Any news on the production of the  HA-008 OTL tube headphone/pre-amp ? Thanks

 

[applebook]

Hello, folks.
 
How does one change the gain setting? What's the internal jumper look like?

 

[Blotto80]

There isn't one. The gain is set during production and not changeable. 

 

[applebook]

If it's not a jumper, how can it be changed? This poster says that it can be changed easily: http://www.head-fi.org/t/824139/sheer-audio-ha-006-special-edition-dynalo-11x-gain#post_13106744

 

[Blotto80]

Any change would involve soldering. You're going to need to change out resistors. I can make some guesses as to which ones but you should try to message Maniac. Looks like the last time he has here was in Nov of 16 so his account is probably active. 

 

[Maniac]

Yup, still lurking around

 

[Paul Clark]

Hello, folks.

How does one change the gain setting? What's the internal jumper look like?

^THIS

Anyone? I know how to solder, I just need to know the resistor/jumper configuration.