Nectar Sound DIY Electrostat Energizer

[HiGHFLYiN9]

Nectar Sound, purveyor of the Pollinator and now the Hive headphones, has a DIY amp published on the website. I reached out and picked up a PCB so I can build this low cost energizer and see how it stacks up against my SRM-252S. Attached is the schematic, BOM, image of a completed amp, and hook-up guide. You can also access everything on the Nectar Sound website. Sajeev has updated the board slightly from the images attached to hold a pair of CL-90 inrush limiters to prevent blowing a fuse on start-up. I'm in the process of gathering the parts now, but wanted to post this to archive the build and see if anyone else was building (or has built) one. 

Nectar1p0_HeadphoneAmp_Rev2_BOM (1).xlsx

[kevin gilmore]

no 5.1k series resistors on the outputs is a super bad idea. definitely bad for the headphones and a safety issue if the mosfets ever short.

[HiGHFLYiN9]

Thanks Kevin, very helpful. I will pass this along. Glad you had a chance to look. 

[spritzer]

The bias supply is also the incorrect polarity and I for one would completely redo it.  It has enough headroom to regulate it or do a better voltage divider and a dedicated ballast resistor on it.  The output devices are also mehhh at best.  Output capacitance is 106pf which means the output of the amp is higher than the headphones.  The Cob should be as low as possible so this is a problem and will severely color the sound.  Think Cavalli Liquid Lightning

[kevin gilmore]

if that is really MINUS 645 volts as the bias, bad things going to happen to the diaphrams.

Flip directions of D3 and D6, change R10 to 5M

 

Edited September 11, 2020 by kevin gilmore

[HiGHFLYiN9]

Thanks for the feedback gentlemen. I think if any little quirks can be ironed out this could be a low-cost, accessible offering for entry-level electrostat DIY.

The bias supply is indeed negative. Forgive my ignorance but what would happen to the diaphragms if negative voltage is used? I was searching Google and digging through old posts but couldn't find a definitive answer. Would the 5.1k series resistors go between the positive outputs (L+, R+) and the headphones? 

[kevin gilmore]

4 x 5.1k resistors in series with all 4 outputs L+,L-.R+,R-

changing the bias voltage to negative means that any dust that gets inside the headphones will accumulate on the diaphram. Definitely not what you want.

Edited September 11, 2020 by kevin gilmore

[spritzer]

Minus bias has often been tried and well... it never works.  Enough issues with electrostatics even if they aren't a magnet for dust. 

Next step would be a whole new output stage for that amp to minimize the output capacitance as mosfets just don't work in this role.  Drop the load resistors for a CCS and the amp should perform a whole lot better. 

[gepardcv]

16 hours ago, spritzer said:

Think Cavalli Liquid Lightning

To be fair, the one time I heard it, the LL made the 009 sound oh so dreamy...

[Emooze]

Compared to what?

 

Also nightmares are dreams too.

[spritzer]

First time I heard it I wondered if Cavalli was on crack... then I saw his websites where he was a "leader of men"...   

[jamesmking]

On 9/11/2020 at 12:03 PM, kevin gilmore said:

if that is really MINUS 645 volts as the bias, bad things going to happen to the diaphrams.

Flip directions of D3 and D6, change R10 to 5M

 

moar voltage is moar good... everyone uses +580V bias voltage why?... convention, lack of imagination, no willingness to innovate and because its easy! No one knows the origins of this "standard" few dare to question its validity... True leaders and visionaries dare to be different and go that extra electron or two even if it cost more and requires more engineering. 645V is clearly moar than 10% bigger/better than the conventional "standard" everyone lazily adopts. 🤪 the fact this can be achieved in such a small amplifier is even more testament to next level, next generation engineering effort put into this remarkable amp. Occam clearly stated that perfection is reached not when nothing else can be added but when nothing else can be taken away. Look at the size and complexity of the full T2 (but then it uses valves which are obsolete technology, environmentally unfriendly, dangerous inefficent space heaters) and even the behemoth that is the T2 cant manage to reach the bias voltages of this seeming humble and simple amp. This amp is Occams razor in its purest form. Who else would dare to run bias voltages through a 5 pin DIN plug? they said it could not be done, they said a DIn plug is not rated for more than line level voltages... they were wrong, just as they were wrong about the +580V convention. This amp is just full of innovative and convention breaking, ground breaking, diaphragm breaking and heart breaking design choices.

... and next week a stax amplifier based on a dual 741 opamp with zero feedback powered by energy harvesting the heat from a T2 or megatron..

Edited September 12, 2020 by jamesmking

[HiGHFLYiN9]

Guess it wouldn't be head-case without a classy high level-of-effort shitpost 🤪

Anyway... still gonna build it. Thanks KG for the good info. 

[jamesmking]

1 minute ago, HiGHFLYiN9 said:

Guess it wouldn't be head-case without a classy high level-of-effort shitpost 🤪

Anyway... still gonna build it. Thanks KG for the good info. 

Seriously, don't run the bias at 645V and dont run bias through a DIN plug.... 

[HiGHFLYiN9]

No I know, thanks. DIN is not rated for that voltage at all and the current design is 580v.

[spritzer]

Funny enough I was buying some din plugs for the Monolith electrostatic headphones at the local store this week.  They only found the metal ones and asked why I was insisting on the all plastic units...  😂

[HiGHFLYiN9]

8 hours ago, spritzer said:

First time I heard it I wondered if Cavalli was on crack... then I saw his websites where he was a "leader of men"...   

Hah! I hope this is true 😂

Edited September 12, 2020 by HiGHFLYiN9

[spritzer]

There were pictures of him in a robe preaching to us mere commoners so yeah... 

[Pars]

4 hours ago, HiGHFLYiN9 said:

Guess it wouldn't be head-case without a classy high level-of-effort shitpost 🤪

Anyway... still gonna build it. Thanks KG for the good info. 

 

Looking at the design, and with this info, I'm not sure I'd bother building it. I guess its your money...

[HiGHFLYiN9]

Since there's many people here far more intelligent than I, can't hurt to ask. With the fixes suggested (flip bias polarity, ensure 580v, add 5.1K resistors), would this be any sort of improvement over the SRM-252S? I'm running an SR 407 which is a nice set but nothing fancy. I'm trying to experiment with more mid-range electrostatic gear so when I inevitably get something higher-end later I'll appreciate it more. The total cost of this build is about $300 FWIW. 

[chinsettawong]

Build a KGST.  It won’t cost much more, but it’ll be much better.

[spritzer]

As it sits now, this will be a step down from the 252S. 

[garageboy]

13 hours ago, chinsettawong said:

Build a KGST.  It won’t cost much more, but it’ll be much better.

I guess this and the srx+ are the choice for simpler DIY builds? Now if I can only get some boards...

The nectar was tempting because it's easy to obtain

[mwl168]

2 hours ago, garageboy said:

I guess this and the srx+ are the choice for simpler DIY builds? Now if I can only get some boards...

The nectar was tempting because it's easy to obtain

Don’t forget Kevin’s electrostatic CFA amp. 

[HiGHFLYiN9]

13 hours ago, spritzer said:

As it sits now, this will be a step down from the 252S. 

Okay, that makes the decision an easy one then. If anyone needs a lightly used Hammond 272BX let me know.