The perfect load for an OTL

[fdegrove]

OTL

Hi guys,

FWIW, the Philips speaker mentioned before here has actually an impedance of 800 Ohm NOT 600 as stated.
Most modern OTL's would be happy to see a load of 16 Ohms already and the higher the merrier I'd say.Especially important for a woofer or full range design.

Rgds,😉

 

[fdegrove]

HIGH Z SPEAKERS

Guys,

I'm not sure if it's any use to you:

Philips 800 Ohm speakers.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

Diameter 203mm
Efficiency 97dB SPL @ 1m, 2.83V, 8 ohms (1W)
Re 5.2R
Z 7R
Fs 46Hz
Qms 2.28
Qts 0.63
Vas 100 liters
Pe 15W
Xmax ± 0.7mm

Note that the data given are for its 8 Ohm counterpart.

Rgds,

 

[Bill F.]

Interesting stuff, Frank.

Thanks for posting it.

Bill

 

[fdegrove]

OTL

My pleasure,Bill

Cheers,😉

 

[Bill F.]

Frank,

Do you own these drivers? If so, I'm curious about their alignment and how you're driving them.

Bill

 

[fdegrove]

OTL SPEAKERS

Hi Bill,

I wish.
I think the easiest way for you to go about contacting the owner:

http://www.vt52.com

If you look for site info and click that you will find his e-mail address.
His name is Jim de Kort.
Also if you right click on the posted images and take their properties you will see the link straight away.
Er,provided you run Windoz.😉

Although I don't have any personal experience with these beasts,I understand they sound pretty good but are reported to be fragile.
Long coil wire to get the 800 R,I guess.

Cheers,

 

[Denis]

By the way, can anyone tell me how typical output transformers pass anything close to the spectrum of human hearing with such great inductance values? Having displayed my tube ignorance, I'll now display my output transformer ignorance.


The self inductance of an output transformer is connected in parallal to the load and eats quite a small amount of output tube current to induce some flux density in the core. The higher this inductance the better from the viewpoint of low frequency reproduction.

In contrary the HF response is determined by a series leakage inductance and a set of shunt capacitances istributed by the whole equivalent circuit of the OPT in quite complex manner. There is no universal equivalent circuit, which correctly simulates any OPT. Generally the lower these leakage inductances and shunt capacitances the better.

There is no problem in gettingvery ide full-power bandwidth of an OPT. What do you say of a frequency responce from 12 Hz to 190kHz (-3 dB) at full output and from 1Hz to 190kHz at lowlevels? This is a routine thing with a push-pull output transformer.

The heavely DC biased SE OPT is more difficult to be made equally perfect, but nevertheless it is always possible to make the OPT an unsignificant component as to distortions and frequency response of an amplifier.

Moreover, the presence of output transformer in amplifier circuit is actually a great advantage and is to be seriously examined in respect to solid-state designs too.