[boomana]

I'm going to try out my FirstWatt F1 and Heed Obelisk integrated (40w) and see what happens.

 

[kevin gilmore]

So the impedance is about 2700 ohms, and the maximum
volage is 1000 Vpp? Single ended right???

Should be easy for me to come up with a direct drive amp
that does that. Half a BH with the rails at +/-500 and the
bias turned up to 15 watts per tube, one tube per channel.

 

[fulltruth]

The TRS version is single ended while the XLR version is not.

Edit: Kevin, I forgot to say that I can't think of anyone better to design an amp for the H2! I look forward to hearing it someday.

 

[boomana]

Quote:

Originally Posted by kevin gilmore /img/forum/go_quote.gif So the impedance is about 2700 ohms, and the maximum volage is 1000 Vpp? Single ended right??? Should be easy for me to come up with a direct drive amp that does that. Half a BH with the rails at +/-500 and the bias turned up to 15 watts per tube, one tube per channel.

Do it!

 

[spritzer]

Quote:

Originally Posted by kevin gilmore /img/forum/go_quote.gif So the impedance is about 2700 ohms, and the maximum volage is 1000 Vpp? Single ended right??? Should be easy for me to come up with a direct drive amp that does that. Half a BH with the rails at +/-500 and the bias turned up to 15 watts per tube, one tube per channel.

According to the specs the maximum input voltage is 200v, maximum current 20mA+20mA driver and minimum impedance 1k.

Here they are:

 

[kevin gilmore]

200 volts RMS into 1kohm is 40 watts.

While i can do that no sweat, i think that something has to
be wrong here. That is 80 watts on your head full blast. No matter
how inefficient these things are, And the real heil transducers from
30 years ago were certainly inefficient (i still have one that works)
that could work out to almost .5 acoustic watt per side which is
way past dangerous.

In any case that would work out to a bridged amplifier with
+ and - 150 volt rails. This is easy.

Not going to be cheap however.

Something has to be wrong with the impedance number, or that
is the minimum impedance at whatever resonance is. Piezo films
are usually much higher impedance.

Any of the large krell amps could do this kind of voltage swing no
problem.

 

[jinp6301]

Quote:

Originally Posted by boomana /img/forum/go_quote.gif Dew eet!

I fixed it!

 

[spritzer]

Quote:

Originally Posted by kevin gilmore /img/forum/go_quote.gif 200 volts RMS into 1kohm is 40 watts. While i can do that no sweat, i think that something has to be wrong here. That is 80 watts on your head full blast. No matter how inefficient these things are, And the real heil transducers from 30 years ago were certainly inefficient (i still have one that works) that could work out to almost .5 acoustic watt per side which is way past dangerous. In any case that would work out to a bridged amplifier with + and - 150 volt rails. This is easy. Not going to be cheap however. Something has to be wrong with the impedance number, or that is the minimum impedance at whatever resonance is. Piezo films are usually much higher impedance. Any of the large krell amps could do this kind of voltage swing no problem.

While the document is riddled with translation errors it's hard to mess up the numbers but since Take T said the dielectric strength of the diaphragm to be 1kV that could be the right number. The 96db number would be comparable to the same number Stax posts for their headphones though the voltage they use is higher, 100v rms compared to the Take T 100v p-p

If the maximum voltage is 1kV and the max current 20mA then each ear piece can handle 20w of power and that is insane so the 40w number is even more nuts. The 200v/20mA is a much more reasonable figure. The 1kohm is certainly the lowest they reach and it might even just be a spike somewhere while the nominal impedance is much higher.

Takei is willing to post the schematic so maybe somebody should host it for him.

 

[kevin gilmore]

I have an unlimited amount of free hosting space.

and in 2 weeks it will be on an unlimited gigabit line.
have him email me what he wants posted and i'll put it up
and supply links.

Need to figure out whether the specs are RMS or P-P voltages.
Would not want to overdesign the amp and have the elements
fry, nor would i want to underpower the amp.

 

[spritzer]

Some of those participating in the group buy should drop him a line with regards to the schematic. I'm staying firmly in the electrostatic court until Take T releases a version with build quality comparable to either of the Stax Omegas.

Has anybody opened up the transformer box and checked how it is wired, p-p or SE? That should shed some light on whether the measurements are RMS or not.

Btw. Very nice connection. All I have is 60mbits and most is lost over the oceanic cables...

 

[Duggeh]

The electronics now being disscussed here are beyond the scope of my knowledge but I am excited about the interest from Dr Gilmore.

Spritzer I'll be happy to send you the set I have for you to try after they've been to the UK meet, should you be interested. I can understand your opinion on them Re: build and construction.

Has anybody opened up the transformer box and checked how it is wired, p-p or SE? That should shed some light on whether the measurements are RMS or not


I opened up the case, do the pictures in the review thread shed any light?

 

[fulltruth]

Sweet avatar Duggeh! When Chuck Norris wears Jecklin Floats his enemies' fear prevents their laughter!

edit: Yeah, I know, it's the Ergo AMT in the pic (right?)

 

[spritzer]

Quote:

Originally Posted by Duggeh /img/forum/go_quote.gif The electronics now being disscussed here are beyond the scope of my knowledge but I am excited about the interest from Dr Gilmore. Spritzer I'll be happy to send you the set I have for you to try after they've been to the UK meet, should you be interested. I can understand your opinion on them Re: build and construction. Has anybody opened up the transformer box and checked how it is wired, p-p or SE? That should shed some light on whether the measurements are RMS or not I opened up the case, do the pictures in the review thread shed any light?

The world doesn't need another Lambda, great drivers in a crappy housing. I would love to have them but I doubt I'd have much time to use them and that would really be a shame.

I looked at the picture and it didn't tell me a lot so I guess we'll have to wait for the schematic. It would be interesting to compare it to a XLR model though. I did however learn that the step up ratio is 20.91:1 if the numbers in the specs are correct. That is nearly the same as Stax used in their adapters.

 

[kevin gilmore]

These headphones are only 2 wires per channel. So there is no
difference that the headphone see's if the source is balanced
bridge or unbalanced.

A solid state amplifier in bridge mode is easier to build because
of a better selection of lower voltage devices.

This is completely different from the stax headphones which are
3 wires and require a balanced bridge drive.

 

[spritzer]

Quote:

Originally Posted by kevin gilmore /img/forum/go_quote.gif These headphones are only 2 wires per channel. So there is no difference that the headphone see's if the source is balanced bridge or unbalanced. A solid state amplifier in bridge mode is easier to build because of a better selection of lower voltage devices. This is completely different from the stax headphones which are 3 wires and require a balanced bridge drive.

I was wondering whether Take T changed the transformers on the XLR model to a CT secondary but I guess it is same internally but with a separate ground paths due to the 4 pin plug. The amp choice (SE or differential) doesn't matter as much as the quality of the amp and the whole signal chain.

Who wants solid state when you can have and OTL SET amp?

They aren't like an electrostatic transducer but I wonder if a Stax amp could be used for differential drive with the bias left out. A Stax adapter is basically the same on the inside except for the bias unit and a CT'd secondary.