DIY T-amp and Full range drivers

by extra_action on Budget Minded
Basic room setup
close-up of not ideal listening posistion
speaker-45
speaker-90
amp and power source
amp and power source 2

Description

For years I have been fascinated with the class D-amp, most notably the Gaincard. Its supposed ability to deliver clear, precise, fast sound powered by nothing more than a few volts and at a ridiculously low price had made it a darling with DIY audiophile enthusiast. My own experience to date had been with the classic Sonic T-amp bought for not more than $30. From the outset its ability to portray instruments that sound pretty real had left me charmed but wanting more.

So I decided to build my own system using what basic electronic skills I had and peruse the web for those that I didn t

The Amp

The amp is based on a kit manufactured by Autocostruire 2020 which in turns uses a Tripath 2020 chip as its foundation. I modded the kit to use all internal silver wiring, and did away with the AC power option and instead used a 12V DC power supply for its natural stability- this is an idea obviously borrowed from Red Wine Audio and the like who have always been profits of DC power. The cell and amp are each housed in separate aluminum chassis, which are 3”x4”x4”. The face plates are custom milled. But here is the rub, it only delivers 20W of power per channel

The Speakers.

To accommodate this little amp with its excellent sonic imaging and sound stage I decided to build a set of full range single driver speakers. The speakers use 3.5” Fostex drivers whilst the cabinet is based on a tried and tested double base reflex enclosure. I decided to treat myself and build the speakers out of ¾” MDF with Zebra wood veneer. Costly but unique and having the grain waterfall from the lid to the face made all the effort well worth it. All internal wiring is silver along with the terminals. I have no idea on how to measure a speakers performance, except by the old subjective way. I would appreciate any help on how I might go about measuring the performance with simple software.

The Source

This one still needs plenty of work. I am currently using a 3rd generation IPOD spooling uncompressed WAV files. I have been thinking about going analogue but have no idea where to start so any help would be greatly appreciated

I think that in the end the effort has been worth it. The sound is wide, extremely fast and organic. It’s not neutral with the bass a little soft and the mid pretty forward. But the instrumentation is clear and “real”. I have only been running the system for about 10 hours so plenty of burn in time to go but I find myself definitely wanting more. I am in no way suggesting that there are not amplifiers and setups out there that would not do a significantly better job, but not at this price point. My reference system is an all Linn based aktiv system http://forum.audiogon.com/cgi-bin/fr.pl?vopin&1095824323 and although I find this system extremely gratifying and appreciate is honesty neutrality and speed my bedroom system offers a character that is both engaging and wanting.
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Components Toggle details

    • Fostex 3.5 Custom cabinet
    A double bass reflex cabinet with a lower port tuned to 60Hz.All silver internal wiring and posts
    • Tripath 2020 Custom
    Tripath 2020 chip based amplifier. Powered by 12V DC. Separate chassis for each
    • Apple Ipod 30Gig
    3rd generation ipod 30gig

Comments 11

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extra_action
A very cool approach! and lots of work.
I wonder if you are still using the headphone jack on the ipod instead of the line out on the dock. from my experience the line out is not amplified therefore doesn't distort when driven. maybe your gear somehow neutralizes that?
my experience is with the same 3G ipod, except in my car system.

(btw: cool apt from your other pics of LR. sorta looks like SF.)

audioalways

Isamu Nogichi was a fantastic designer. I took in a "life's work" exposition at the Smithsonian a couple of years ago and nearly wept at the masterful sculptures he did. I'll never look one of those Akari lamps (like yours) the same way again...

The link was cool- thanks. Your zebra endgrain matching is perfect- very dramatic!

Take Care.

6ix_6ixty_6ix

Owner
The lamp is a Noguchi and the chaise has always been one of my favourite spots for listening to music.
Thanks for the generous comments. I actually just gave the system to my brother and i am on the last stages of completeing my new setup (Jordan drivers amd chip amp based.)
I will post images as soon as it is complete. In the meantime here is a link to my blog which documents the constrcution process as all the components are DIY:
http://web.mac.com/noteldov/iWeb/DIY%20Paradise/Audio%20Projects/Audio%20Projects.html

Cheers and thanks for looking

extra_action

nice lamp! is it an Isamu for Akari? Nice Corbu' lounge, too- great for headphone listening. Classic system- nice job.

6ix_6ixty_6ix

as far as the bass being soft and mids forward - have you tried a source other than an ipod? - that's their sonic signature IMHO

angaria

"This one still needs plenty of work. I am currently using a 3rd generation IPOD spooling uncompressed WAV files. I have been thinking about going analogue but have no idea where to start so any help would be greatly appreciated"

Try using Apple Lossless. it's bit for bit as the orignial. It saves space, most cd's are fitted to 350 MB using Apple Lossless. No Sonic degridation.

I personally have the the Apple Airport Express.

read this Apple Airport express Sterophile Follow up

and I have plans connecting it to a external DAC then to the the Sonic T-amp drivin' Fostex FE103E in 5L BR.

[email protected]

Beleve it or not Radio Shack has pretty nice SPL meters and re cheap. I got a digital one it may have been around 20.00

I don't know of a USB meter but would not be suprized if they make one.

mark02131

I believe that you need at least 200hours or more of play time to determine whether the midrange hump is part of the driver's idiocyncracy or something else. If it is the earlier, perhaps some driver basket damping or other modding might be on call to reduce that characteristic. In regards to the soft bass, you might need to get a step baffle compensation unit to add the bass that is missing, of course at expense of efficiency OR get a Behringer unit that will do the sound tailoring for you($200 or less?.) An intriguing execution of a system. For what I see, very difficult to improve it without either detracting from its merits or adding further deficiencies. Nice and affordable.
Paul K

bemopti123

Owner
Thanks for the kind words Mark02131. I will scout around for the SPL meter and post how things shake out. Don't quite know were to begin at diyaudio
Do you know of a USB meter that will run the test on a laptop?
Oz- when listening i actually move the chaise or sit on the floor on the opposite side of the room, at the mid point of the speakers. Ther room is approx 10'x10'. So i am in a better position to test the sound stage. Listening on the chaise in the picture posistion simply makes me deaf in my right ear

extra_action

Love your system. I just love DYI electronics. That is a great little amp. Have you ever checked out
http://www.diyaudio.com/

A great way to test your system is to use a stereophile test cd and an SPL meter. These recording have a warble tone at different frequences as each one of them play your spl meter should be about the same DB level. There are instructions that come with the CD's that will help you test. Greg Job anyway...

mark02131

>To accommodate this little amp with its excellent sonic imaging and sound stage I decided to build a set of full range single driver speakers<

How do you know about this parameter of performance if you are indeed listening from the position you have pictured?

Oz

ozzy62

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