stax mafia electrostatic portable

[yabba235]

30 minutes ago, kevin gilmore said:

there is no way this is going to be a diy product.

I understand, and when will it be ready to buy?

[yabba235]

I have one more, maybe a stupid question - how are these four amplifiers connected - there is no phase inverter there and looking at the pcb I can see that the inputs in the channels are connected (?) - I'm tired of this matter and I can't sleep because of it - can you explain it to me ?

[kevin gilmore]

well there are 2 ways to do this.  instrumentation amp and inverting/non inverting.

pick one, they are roughly equivalent.

[justin]

On 1/13/2022 at 3:49 AM, HVRV said:

This is the latest design might look similar to Stax-D10 but the fact is different.

Why under cut a supposedly original design by making it look just like the SRM-D10? 

Seems to show a lack of confidence

[yabba235]

I have a certain idea - you could add a direct input for a balanced signal - my qudelix gives 4V rms in this mode - bypassing the potentiometer, which is not of high quality - anyway, it is unnecessary in this configuration because the gain control is taken over by the phone or the qudelix itself (of course it writes about my case)

[s2030081]

Maybe a good idea to have a bypass mode just like T8000?

[yabba235]

On 2/8/2022 at 8:26 PM, kevin gilmore said:

well there are 2 ways to do this.  instrumentation amp and inverting/non inverting.

pick one, they are roughly equivalent.

Nice joke

I simulated your schematic in topology from pcb and it does not work in any way  - only in single mode, not bridge. And I know it works to you - some "king of magic"

I always liked to check the circuit in the simulation before I did something - we have something in common

 

[kevin gilmore]

if you can't copy it now...

 

Edited February 10, 2022 by kevin gilmore

[yabba235]

3 hours ago, kevin gilmore said:

if you can't copy it now...

Thank's, but my problem is when I connect them single amp like on a kerry pcb together, the simulation does not work. And I can see that it works in real - maybe I'm doing something wrong in the simulation ??

[yabba235]

Now all works - I had a short break with electronics so I was a bit rusty

 

[yabba235]

Born in pain - no semiconductors on the market- but case is here !

Introduction my portable estat with necessary modifications

[yabba235]

19 hours ago, selfreserv said:

looks great
what does it have inside and where can I get a similar \ buy?

Inside is Kevin Gilmore estat portable with my modification and you can't buy it - it's d.i.y.

[Inu]

Made with double sided bread board.  HVPS (LT8365) are on the way from JPN.  

I planning to divide it into four and stack these in 2 or 4 layers, but I don't think it will be a size that can be called "portable" but I will try...   

[JoaMat]

Lovely – smds on breadboard. Excited to see lt8365 on a similar board. 

[yabba235]

14 hours ago, Inu said:

Made with double sided bread board.  HVPS (LT8365) are on the way from JPN.  

I planning to divide it into four and stack these in 2 or 4 layers, but I don't think it will be a size that can be called "portable" but I will try...   

As for your pcb board: You have  big cohones, dude  !!

BTW:

Can you share the source of lt8365 chips in japan ? - I can order them there because only this is what I still need to finish the project.

 

[Inu]

I also searched for the LT8365 but couldn't find a way to buy it as a part.

I can't wait until next year, so It's expensive, but I bought modules (boards). This is up to + or -280V, so I need to make few changes.

https://strawberry-linux.com/catalog/items?code=18365

This shop doesn't have an option to ship to the US, so I got help from a friend in JPN.

[yabba235]

54 minutes ago, Inu said:

I also searched for the LT8365 but couldn't find a way to buy it as a part.

I can't wait until next year, so It's expensive, but I bought modules (boards). This is up to + or -280V, so I need to make few changes.

https://strawberry-linux.com/catalog/items?code=18365

This shop doesn't have an option to ship to the US, so I got help from a friend in JPN.

Can you have contact with him? I am also happy to buy these modules. I found them myself a few months ago ( find my post on diyaudio forum) but I have no friends in Japan.

Without these chips I will not finish this amplifier.

[s2030081]

On 8/6/2022 at 2:32 AM, yabba235 said:

Can you have contact with him? I am also happy to buy these modules. I found them myself a few months ago ( find my post on diyaudio forum) but I have no friends in Japan.

Without these chips I will not finish this amplifier.

Maybe you can try to use parcel forwarding service.

I am not living in US so I don't know which provider is better.

[Inu]

Can you send me a PM?

[yabba235]

On 11/10/2022 at 10:30 PM, selfreserv said:

hi @yabba235

i want to build the same one for my kse

except bias 200 v - did you make any other modifications?

Only a few: bias voltage selection, input selection ( bal/unbal) and power on/off.

The first two are implemented based on bistable relays - connecting them requires only momentary power consumption - important when powered by batteries.

Last is simple monotstabile switch.

Because of the relays, the housing is large, but maybe someday I will find smaller relays or think about another solution.

(Instead of a discrete stage, I would see a high-voltage OA here :))

Edited November 14, 2022 by yabba235

[yabba235]

45 minutes ago, usa_love said:

all the high voltage op amps I've seen have extremely low slew rates, which makes the sound sluggish and bad. I firmly believe that it is much better to use small transformers with a large transformation ratio. No matter how much I listened to different transistor solutions - the sound through transformers is perceived much better, it is faster, good transformers are able to transmit sound impulses to the drivers much faster.

It's not that bad, apex's integrated amps are good enough. As for the transformers on the outputs, I say no to them!

[kevin gilmore]

full range low distortion transformers for electrostats are very hard to make. physically big and heavy. Here is one of the 2 transformers inside a quad esl63. interwinding capacitance and other issues are critical. So sure you can build a portable with 4 of these. Not really portable is it.

 klh9 and esl56 are much bigger.

all the stax made transformer units perform very poorly.

kgsshv carbon does 100 volts per microsecond. please show me a full range transformer that do this.

if you really think you can build a suitable transformer the size of a 1 inch cube that does the full frequency range and does not ring like a doorbell, you clearly have not tried to make such a thing.

Edited April 14, 2023 by kevin gilmore

[kevin gilmore]

birgir pointed me to this. hvrv portable

闲鱼宝贝详情 (goofish.com)

published price is $380 plus shipping.

someone that reads chinese should buy one.

Edited April 17, 2023 by kevin gilmore

[yabba235]

Hmm, from the translator:

"..Portable (Class A) electrostatic headphone amplifier supports DAC decoding
 Completed the development of the latest portable electrostatic amp, surpassing Stax D10, Sennheiser kse series and domestic products of the same series, push-pull structure, the latest design, the first in China, adaptable to stax or other stax-5pin standard interfaces, and a full range of bias 580 products
     Speaking of why it surpasses most portable electrostatic amps on the market, the reason is that this structure is a COMS current mirror push-pull design. Class A portable electrostatic amplifiers on the market are all class D. Fans should understand the difference between class A and class D power amplifiers..."

Sounds familiar.....and quite avant-garde housing design

 

 

[Guest]

On 4/14/2023 at 9:37 PM, kevin gilmore said:

full range transformer that do this

it would be interesting for me (and I think a lot of people) to find someone's calculations of some (just for understanding) transformers in terms of the slew rate parameters, it seems to me that everything should be fine in transformers with this

I'll try to find someone's research

maybe anyone know or have seen something similar

Edited April 17, 2023 by usa_love