chinsettawong

I would like to add for 2 partially assembled GRHVXXX boards, please.

Are you referring to me?

Bare boards for me.

Preassembled boards will be nice.

A Raspberry Pi + Hifi-berry DAC + Volumio could be a good choice.

Interesting! Thanks for sharing.

Inside the Stax SRD unit, there are a pair of step up transformers for audio signal and a step up voltage circuit for the bias voltage. The audio signal needs to be amplified a lot for it to be played on the electrostatic headphones. Many of electrostatic amps can swing the audio signal to over +/- 400V. The bias voltage for electrostatic headphones also needs to be stepped up from the main AC voltage. For Stax headphones, the bias voltage is 580V. So, the amplified audio signal together with this bias voltage of 580V can actually be more than 1KV.

Happy birthday!

Happy birthday!

You guys make me want to go back to play with my CNC again. I haven't touched It for almost 2 years.

Happy birthday!!!

Could it possibly be this kind of JFet?

Happy birthday!

Make sure that you let me know when you come again next time. Let’s have a beer together.

Aumkar and I had a good time on Saturday. We started the day with a short city tour. I took him to visit the Temple of Emerald Buddha, Grand Palace, and Wat Poh. Then we had lunch with a few of my headphones lover friends. After that, we had a mini headphones meeting. At the meeting, we had Stax SR007 MK1, SR009, My DIY Orpheus Clone, Omega Clone, JF Clone, and of course Aumkar's RR1 headphones. I brought my KGSSHV Carbon, KGST, and KG Grounded Grid, and my friend brought his DIY 300B single ended amp. The RR1 showed very good performance with all the amps we tried. The treble was just right and the bass was impactful and deep. I think they're good headphones for fast music. Aumkar kindly gave me a pair of RR1 and an extra pair of drivers for me to play with. Here are some pictures of the stators, spacers, and dust shield. I'm very impressed to hear that he actually machines down the 4 mm aluminium sheet to 0.8 mm so that he can have the absolutely flat stators. The look and feel of the headphones are good. Aumkar told me that all the cups are 3D printed, sanded, and painted in house. With all these labor intensive works, the result is quite impressive. I basically can't tell that these components are 3D printed at all. All my Thai friends like his headphones and have already asked me to help place their orders with Aumkar.

So beautiful!

I think you've stretched the diaphragms too much.

These are my measurements: I also don’t really know how to read them. However, my headphones’ graphs show pretty similar patterns to the Stax’s 007 MK1’s. Your headphones’ graph is so flat. Maybe you should retest them again. How is your bass compared to the 009S?

Very nice!

Believe me; soon you'll prefer your DIY phones "sonically" over Stax.

Your arcs and headband look exceptional. Very nicely done! Are they 3D printed? What material do you use?

Do you notice that with the new stators you've made, the phones sound less bright?

? It’s nice to see you already get hooked into making the headphones. I’m sure you’ll figure out what is wrong. What spacer thickness do you use?

Very nice!

I believe the 580V Stax bias voltage with 5M ballast resistor is safe for HE90. I have tried the HE90 with some Stax amps in the past, and I didn't notice any problem. However, if it will make you feel better, reducing the bias voltage to 500V and adding additional 5M ballast resistor are the way to go.