• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

Tweeter amplifier (1 kHz upwards...)

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E

ErikdeBest

Member
Joined 2003
ReinoutdV said:
Hi Horneytube,

if you have the opportunity to make specific trannies/amps for specific frequency bands from scratch that is a huge benefit as you can optimise without having the need to take care of unwanted demands of not needed specifications.

That 0.7 W tweeteramp measures straight within 1 dB from 1 kHz to 160 kHz. That is (in my humble opinion) quite impressive for tube gear. If i would have started with a full range amp these numbers wouldn't be achievable.

Of course full range amps are extremely versatile. Exactly the reason why i have them also (and use them as "mid-amps"). But on the frequency extremes it gives you more options to use funny parts / topologies / etc.
So for this tweeter amp i looked seriously into HF-building and applied semi-rigid cabling with surprising results.

Regards,
Reinout
Click to expand...

A while ago I started this thread Output transformer for 100Hz and up, there and in other discussions I heard more than once: why bother, a good OPT can go beyound 20Hz to 20000Hz. On the other hand trafo winders are "complaining" that there are so many compromises in an OPT: lot of windings needed for bass, leading to leakages that are bad for HF, so I wanted to ease their pain :)

I never measured the actual HF of the OPT I described in that thread as I can't measure that high, and subjectively I am probably biased anyway, but I do like that OPT, and I think a lot is due to lower DCR values and insertion losses.

At some point I want to buy a set of these 750gr Lundahl OPTs, https://www.lundahltransformers.com/wp-content/uploads/datasheets/2766.pdf, the 50mA one. I would then put the primaries in parallel, for 12.5H and 100mA, with something as an EL519 as output tube. That could give me 10W from 700Hz and up, and the amp would weight a fraction of a similar with fullrange OPTs. Also, I somehow like the idea of a smaller core, it is subjective and probably not measurable, but I have the feeling that the "micro details" of the music could get lost when they have to be transformed in a large core. :)
 
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