NEW Electrostatic headphone amp

oguinn · **Reply #15 on:** February 19, 2020, 04:50:54 AM

Quote from: Doc B. on February 18, 2020, 12:40:03 PM

I guess it's time for that VTVM kit.

Also a tube tester kit.

caffeinator · **Reply #16 on:** February 19, 2020, 06:45:20 AM

I'm interested - looks like an interesting build and sounds like it may give me an opportunity to use my old Heathkit VTVM in the bargain.

grufti · **Reply #17 on:** February 19, 2020, 11:15:59 AM

A megOhm resistor at the end of the + plug of a DMM should be enough to measure that bias supply, assuming that you re-calibrate.

Paul Birkeland · **Reply #18 on:** February 19, 2020, 03:55:36 PM

Quote from: grufti on February 19, 2020, 11:15:59 AM

A megOhm resistor at the end of the + plug of a DMM should be enough to measure that bias supply, assuming that you re-calibrate.

No, it won't. Most modern DVMs are 10M ohms. There's a 20M resistor between the bias supply and the bias pin on the output jack, so an extra 1M of resistance isn't going to do much. Even measuring the raw bias supply with a 10M meter pulls it down pretty far. I intentionally designed the bias supply to be ample for the task, but not ample enough to be harmful to meatware.

It is possible to measure each chunk of the voltage multiplier that creates the bias voltage, but it's a bit tedious.

johnsonad · **Reply #19 on:** February 22, 2020, 04:31:36 AM

My opinion is a finished product at first and if demand is there (which I feel will taper out, quickly), then it could graduate into a kit. You could also consider a short manual on how and where to mod the amp (e.g., cap swapping, magic resistor swapping, etc).

I've know you guys long enough to know how much work goes into the manual, kit packaging, stocking supplies, online support of a product, etc. I also have owned three finished amps that PB has build over the years and his build quality is second to none and worth the extra cost. There would be minimal support needed on a finished product.

Another thing to consider is who you are competing against. Unfortunately they have earned their nick name of the Stax Mafia for many reasons. The one that bothers me most is how they are able to sway opinion on products. Getting an amp into circulation and the reception of that amp should also be factored IMHO.

Lastly, these are electrostatic headphones..... The market is very small based on the entry price of the headphones and that makes for an even pickier costumer and all that comes with that type of customer......

Just my two cents

Alonzo · **Reply #20 on:** February 22, 2020, 11:32:21 AM

I'll admit up front that I'm biased but I think it's an opportunity to introduce ES headphones to a new customer. Just googling ES tube amp brings up three that are in the multiple of thousands (1700 to 6200). That price ranges keeps out a lot of customers and leads to things like the Stax mafia.
You have to decide the form factor that works for the business but there is an opportunity, maybe a limited run of Pb buiit to seed the market, there are options. Shoot for something between the BHDac and a new DIY kit. Any open backed headfi customer is right there for the taking, these headphones compare and beat most open backed ones on the market but are limited by the availability of a good amp to drive them. You've solved this. The choice is to jump in or not...
I have limited experience with Stax amps and headphones but the ones I had had a hard time beating out my HD800's and Mainline so I think you can compete easily with a new ES amp available for modestly priced but poorly driven headphones (the complaint of most ES users and reason for defaulting for Stax amps).

oguinn · **Reply #21 on:** February 22, 2020, 11:34:36 AM

If I picked one up Iâ€™d try it with those $285 Nectars.

frankg · **Reply #22 on:** February 23, 2020, 06:27:33 AM

I have only build a Crack with Speedball still I think I have figured out much of what is going on. On the left are separate channels each with an input and output tube. I found 3 power supplies, 4 if that large tube has something to do with power. What is that tube? Two standoffs for the C4S boards and stepped attenuators. Each section seems very simple with a clean design. As a second kit it looks very doable.

I'm going to change what I wrote previously, I will buy the kit if it is available, if not I'll still buy the finished version.

Paul Birkeland · **Reply #23 on:** February 23, 2020, 11:22:34 AM

Quote from: frankg on February 23, 2020, 06:27:33 AM

What is that tube?

It's a damper diode to soft start the high voltage supply.

The standoffs connect the top and bottom plates together for a little extra rigidity.

frankg · **Reply #24 on:** February 23, 2020, 05:18:05 PM

A diode? Awesome!

Doc B. · **Reply #25 on:** April 24, 2020, 12:46:56 PM

We've had some interest expressed by long time customers in having an electrostatic headphone amp built to order. PB and I had a meeting today to discuss pricing and production. What makes sense is to try to get 5 orders going, which makes things like fabrication of the cabinets and custom connectors cost effective. Price will be $1500. So far it looks like we have two interested customers.

I'm attaching a pic of the latest prototype that Peebs put together, for Sajeev Ranasinghe of Nectar Sound. His impression -
"Sounds awesome!!! Lots of bass, smooth, and can handle these headphones."

There are jacks for both styles of Stax headphone connectors, so this will work with any Stax and also Nectar Sound and Koss headphones. We're digging the yellow finish on this one, and I have asked for a red one to sit next to my red Neothoriator amp.

Ping me at [email protected] if you would like to order one.

2wo · **Reply #26 on:** April 24, 2020, 05:19:34 PM

Looks like it could Be at home in a Civil Defense office...John

Alonzo · **Reply #27 on:** April 24, 2020, 06:19:33 PM

Hey Doc!
I'll trade you my red one for the Neo, tell you what, I'll throw in some gear that has actually left the planet and we can call it even.

Alonzo

Pflugshaupt · **Reply #28 on:** June 09, 2020, 12:10:05 AM

Did you find the 5 customers for the trial run? Will there be a kit? I definitely would be interested in a kit version to drive my Stax 007.. if this amp can deliver the necessary power.

Doc B. · **Reply #29 on:** June 09, 2020, 05:18:14 AM

At this time we are just taking orders for built amps. PB was working on a really nice looking green one the other day.