Thought on OTL tube amps

Perhaps I should put my $0.02 here from an end-user perspective.

I have owned at least seven (7) different OTL tube amps, some are big brands, some are DIYs from experienced (10+ yrs) tube amp hobbyists with extensive engineering experience.

IMHO, OTL tube amps are reliable if you understand their operation limitation first. I found that:

1) OTL tube amps do not work well under 4 ohm or less speakers. Even some transient passages at 2 or 3 ohms may blown the tubes. This is not specific to the tube type.

2) OTL tube amps are much less tolerant to wide impedance swing. The more stable the speaker's impedance, the better.

The best sound I got from OTL amps is when I use them to drive impedance-friendly monitors, with the aide of quality subwoofers covering 180Hz-250Hz and below.

Hope this helps.

Using the Zero nullify an OTL status.You already get rid of transformer then put new Transformer?Whats happening? going in circle?

I'm convinced…I'm immediately removing the output transformer from my amp…those wire cutters are around here somewhere...

bsimpson

Perhaps I should put my $0.02 here from an end-user perspective.

I have owned at least seven (7) different OTL tube amps, some are big brands, some are DIYs from experienced (10+ yrs) tube amp hobbyists with extensive engineering experience.

IMHO, OTL tube amps are reliable if you understand their operation limitation first. I found that:

1) OTL tube amps do not work well under 4 ohm or less speakers. Even some transient passages at 2 or 3 ohms may blown the tubes. This is not specific to the tube type.

2) OTL tube amps are much less tolerant to wide impedance swing. The more stable the speaker's impedance, the better.

The best sound I got from OTL amps is when I use them to drive impedance-friendly monitors, with the aide of quality subwoofers covering 180Hz-250Hz and below.

Hope this helps.

This is a good summary bsimpson. And that's quite the experience with so many different OTL's, although you don't list the brands amps/speakers. Thanks for sharing. I particularly take note of your last comment - aide of quality subwoofers 180hz - 250hz. Very difficult to do going this high in the frequency range, even in a dedicated space. 

I use the Classic Audio Loudspeakers model T-3.3 at home. It goes down to 20Hz. A set of our M-60s has no troubles driving them to very high volume levels with very satisfying bass (shakes the house). M-60s are full power down to 2Hz. 

Like **any** other amp, if you want to hear what its really capable of, its a good idea to put it on a speaker to which it is well-suited.