JJ 2A3-40 DHT Single ended triode, power amplifier

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SteveTheShadow
Posts: 1042
Joined: Thu Sep 12, 2013 5:24 pm
Location: S Yorks
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JJ 2A3-40 DHT Single ended triode, power amplifier

Unread post by SteveTheShadow » Mon Oct 16, 2017 9:48 pm

Image

This is my current project

Will be wiring it up his week.
Very simple, no frills.
Very pink Missus! :lol:
DIY NVA amplification ( roughly equivalent to NVA A60) BTE Designs passive preamp, BTE Designs Lenco L75 turntable, Rega R200 arm, Goldring E3 cartridge, NVA Phono 1
Musical Fidelity M1 DAC, AppleTV4 with Apple Music subscription, ripped CDs streamed via WD MyCloud Home Duo NAS, with PLEX media server.
Speakers - Large sealed cabs, with Fane 12-250-TC 12" full range drivers.

SteveTheShadow
Posts: 1042
Joined: Thu Sep 12, 2013 5:24 pm
Location: S Yorks
Great Britain

Re: JJ 2A3-40 DHT Single ended triode, power amplifier

Unread post by SteveTheShadow » Tue Oct 31, 2017 11:39 pm

Working in the system now.
Image
6W of lovely SET power. :lol:
Last edited by SteveTheShadow on Tue Oct 31, 2017 11:39 pm, edited 1 time in total.
DIY NVA amplification ( roughly equivalent to NVA A60) BTE Designs passive preamp, BTE Designs Lenco L75 turntable, Rega R200 arm, Goldring E3 cartridge, NVA Phono 1
Musical Fidelity M1 DAC, AppleTV4 with Apple Music subscription, ripped CDs streamed via WD MyCloud Home Duo NAS, with PLEX media server.
Speakers - Large sealed cabs, with Fane 12-250-TC 12" full range drivers.

SteveTheShadow
Posts: 1042
Joined: Thu Sep 12, 2013 5:24 pm
Location: S Yorks
Great Britain

Re: JJ 2A3-40 DHT Single ended triode, power amplifier

Unread post by SteveTheShadow » Tue Oct 31, 2017 11:43 pm

Insides:
Image
DIY NVA amplification ( roughly equivalent to NVA A60) BTE Designs passive preamp, BTE Designs Lenco L75 turntable, Rega R200 arm, Goldring E3 cartridge, NVA Phono 1
Musical Fidelity M1 DAC, AppleTV4 with Apple Music subscription, ripped CDs streamed via WD MyCloud Home Duo NAS, with PLEX media server.
Speakers - Large sealed cabs, with Fane 12-250-TC 12" full range drivers.

SteveTheShadow
Posts: 1042
Joined: Thu Sep 12, 2013 5:24 pm
Location: S Yorks
Great Britain

Re: JJ 2A3-40 DHT Single ended triode, power amplifier

Unread post by SteveTheShadow » Tue Oct 31, 2017 11:46 pm

Inspired by Stu's mammoth semi-omni project, I've got a twin cone tweeter array experiment going.
The mid/bass cones have also been doped with 80/20 Gorilla carpenter's glue/water mixture, to very good effect.
I no longer need the blu-tack rings at the dustcap/cone junction. Good result.
Sounds really rather good:
Image
Last edited by SteveTheShadow on Tue Oct 31, 2017 11:55 pm, edited 2 times in total.
DIY NVA amplification ( roughly equivalent to NVA A60) BTE Designs passive preamp, BTE Designs Lenco L75 turntable, Rega R200 arm, Goldring E3 cartridge, NVA Phono 1
Musical Fidelity M1 DAC, AppleTV4 with Apple Music subscription, ripped CDs streamed via WD MyCloud Home Duo NAS, with PLEX media server.
Speakers - Large sealed cabs, with Fane 12-250-TC 12" full range drivers.

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Fretless
Posts: 3937
Joined: Wed Nov 12, 2014 12:15 pm
Location: Somewhere in Holland
Netherlands

Re: JJ 2A3-40 DHT Single ended triode, power amplifier

Unread post by Fretless » Tue Oct 31, 2017 11:51 pm

Looking good, Steve.

I totally lack the knowledge to do this sort of thing but know that there is a sense of pride when you can turn an idea into reality.

:clap: :guiness;
Main: NVA: P50sa - SSP - A40 - LS6 - Cube3
Digits: RPi 2B/Allo DigiOne/Volumio/Tomanek ULPS/AQ Jitterbug
DAC: Metrum Acoustics Musette CD Transport: Cambridge CXC
Headphones: AQ NightHawk & NightOwl Amp: Schiit Magni-3
DAC: Cambridge DacMagic Plus + Sbooster LPSU

antonio66

Re: JJ 2A3-40 DHT Single ended triode, power amplifier

Unread post by antonio66 » Wed Nov 01, 2017 6:32 am

Great work Steve. :clap: Just out of curiosity have you thought about using a super tweeter?

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wiicrackpot
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Location: Glasgow

Re: JJ 2A3-40 DHT Single ended triode, power amplifier

Unread post by wiicrackpot » Wed Nov 01, 2017 7:18 am

Take a bow Steve, lovely work. :guiness;
Frank...made me do it.

SteveTheShadow
Posts: 1042
Joined: Thu Sep 12, 2013 5:24 pm
Location: S Yorks
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Re: JJ 2A3-40 DHT Single ended triode, power amplifier

Unread post by SteveTheShadow » Wed Nov 01, 2017 10:00 am

antonio66 wrote:
Wed Nov 01, 2017 6:32 am
Great work Steve. :clap: Just out of curiosity have you thought about using a super tweeter?
Yes, but proper ones are bloody expensive and my budget doesn't run to them at the moment. :)
The multiple tweeter technique, was used years ago to get enough top end volume and dispersion when all they had were cones, so I thought I'd revive it. It works very well and cone tweeters are relatively cheap, because there is little or no demand for them from audiophiles.
Thanks for the comments everyone.
The SET was, believe it it or not, inspired by the A20/P/20, which shows me what music is supposed to sound like...and what I've been messing around with for the past five years, sounds nothing like music in comparison. :lol:
The philosophy behind the SET amp you see in the pictures, mirrors the philosophy behind NVA amps ie. keep the signal path simple so as to do the absolute minimum damage to the music signal.
It is a three stage design. The medium gain input stage drives a small power valve, which then drives the single-ended, direct-heated triode output stage.
The power supply is a hybrid bridge rectifier, feeding a choke, then a series of resistor capacitor filters. The feeds to each valve drop off the filters, right where they are needed, minimising the length of the signal path, which is one reason why the power supply runs down the centre of the amp chassis.
Input sockets are right next to the first stage valves.
The results sound like music...nuff said.
I'd gotten myself sucked into the complexity bollocks, ruining my musical enjoyment, which is why I ditched valves and bought the NVA amp. My own amps had become complex where they didn't need to and too simple where a bit more thought would have been useful.
The SET was built from what I had left after selling most of my valves. Copying the NVA, keep it simple and avoid bullshit philosophy and transferring it to the vacuum state arena, has resulted in exactly the same musical benefits.
Richard may be villified by the ignorant twats that pollute this hobby, but his philosophy works with valves, transistors, speakers, you name it. It's their loss if they either can't or won't accept this....Sod 'em 8-)
DIY NVA amplification ( roughly equivalent to NVA A60) BTE Designs passive preamp, BTE Designs Lenco L75 turntable, Rega R200 arm, Goldring E3 cartridge, NVA Phono 1
Musical Fidelity M1 DAC, AppleTV4 with Apple Music subscription, ripped CDs streamed via WD MyCloud Home Duo NAS, with PLEX media server.
Speakers - Large sealed cabs, with Fane 12-250-TC 12" full range drivers.

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Fretless
Posts: 3937
Joined: Wed Nov 12, 2014 12:15 pm
Location: Somewhere in Holland
Netherlands

Re: JJ 2A3-40 DHT Single ended triode, power amplifier

Unread post by Fretless » Wed Nov 01, 2017 10:31 am

Just goes to show - Less IS more !! :dance:
Main: NVA: P50sa - SSP - A40 - LS6 - Cube3
Digits: RPi 2B/Allo DigiOne/Volumio/Tomanek ULPS/AQ Jitterbug
DAC: Metrum Acoustics Musette CD Transport: Cambridge CXC
Headphones: AQ NightHawk & NightOwl Amp: Schiit Magni-3
DAC: Cambridge DacMagic Plus + Sbooster LPSU

SteveTheShadow
Posts: 1042
Joined: Thu Sep 12, 2013 5:24 pm
Location: S Yorks
Great Britain

Re: JJ 2A3-40 DHT Single ended triode, power amplifier

Unread post by SteveTheShadow » Wed Nov 01, 2017 7:02 pm

Chrome barrel feet, upcycled from some old drawer handles, have been attached:
Image

View from the front completes the 50s Art Deco revival look:
Image

Jobzagoodn. :) :)

Rose gold metalflake is the absolute biz for 50s retro design; captures the period spot on.
DIY NVA amplification ( roughly equivalent to NVA A60) BTE Designs passive preamp, BTE Designs Lenco L75 turntable, Rega R200 arm, Goldring E3 cartridge, NVA Phono 1
Musical Fidelity M1 DAC, AppleTV4 with Apple Music subscription, ripped CDs streamed via WD MyCloud Home Duo NAS, with PLEX media server.
Speakers - Large sealed cabs, with Fane 12-250-TC 12" full range drivers.

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