2a3 - for car use?

[oliezt_sayfu]

hello guys
is it possible to use DHT 2A3 Se amp to drive driver(94db sens) in Car stereo ?
thanks ...

[ryuji]

what you should really be asking is for solutions for derriving your b+ voltage. If I remember right in old days they used what they called a vibrator. It generated a low ac voltage which is then fed to a transformer to get your high voltage. In modern compoments best choice is probably a switching psu, which is what ss amps for cars use to get there voltages.

[duderduderini]

http://greygum.net/sbench/sbench101/...es/lvps250.txt
http://greygum.net/sbench/sbench101/...es/lvps250.gif
http://greygum.net/sbench/sbench101/...es/supply4.gif
http://greygum.net/sbench/sbench101/...es/supply3.gif
hope it helps
Nick

[Salas]

Originally Posted by ryuji

what you should really be asking is for solutions for derriving your b+ voltage. If I remember right in old days they used what they called a vibrator. It generated a low ac voltage which is then fed to a transformer to get your high voltage. In modern compoments best choice is probably a switching psu, which is what ss amps for cars use to get there voltages.

A DHT would need some very serious shock absorbing mounting not to chime and groan reading the road.

[aardvarkash10]

Yes, like most things, its possible but it does beg the question - why?

[ryuji]

Originally Posted by aardvarkash10

Yes, like most things, its possible but it does beg the question - why?

Isn't the diy spirit "because I can"?

[kevinkr]

You can, but given the fragility of the filaments it is unlikely that they will last long even with fairly draconian measures at isolating the 2A3 from road shocks. I figure one good pot hole is going to be good for an open filament or two..

Then there is the question of speaker efficiency vs available power, there is a good reason why most car stereos with any pretense at quality are capable of delivering at least 15W per channel into a 4 ohm load. A pair of 2A3 in PP could give you that kind of power, but frankly the 6BQ5 in UL would be a much better choice.

Submini types can be used everywhere else to keep size moderate and are often designed for high shock environments. (6021, 5719, 5902, 5903, etc.)

Good luck!

[aardvarkash10]

...or accept that the technology has moved on and that just because you can doesn't mean you should.

Dunno what the ambient noise level is inside your car under real-world conditions, but I'd estimate it at upward of 24db noisier than your home at best. Idling. Air on or off.

Now do your required power calcs....

This looks like a case of wrong technology for the application to me.

[kavermei]

Thoriated tungsten filaments become very brittle once used (the crystallic structure changes because of the heat); indirectly heated tubes would be much better for this purpose.

For the serious builder, a modified 12V->230VAC car SMPS will easily deliver the required plate/heater/bias voltages.

Kenneth

[rock4016]

The original car radios used tubes, there are several tubes that can run 10-14V on the heaters and up to 25V on the plates. Combine those with some higher sensitivity speakers and you might be ok, it would be interesting to try.

The other option would be to look at military tubes that were designed for Avionics, as those should be able to withstand some shock and abuse and still function adequately.

Also the Milbert amp, designed by David Berning has successfully marketed and still sells it's 30W per channel tube car audio amp, course it's expensive.