OTL's, as a general rule, can sound stupendous. That is, so long as they are VERY carefully mated to the loudspeaker & cabling that they will drive. The higher the nominal impedance of the speaker, the better the OTL will work. The lower the impedance of the speaker, the more that the reactance of the speaker will "modulate" what one hears. Most would refer to this as a lack of "damping factor", but what it really boils down to is a lack of available current in the output stage of the amp.
If you look at the power output on most OTL's, you'll find that their power output actually goes UP as impedance climbs, which is the exact opposite of SS and most tubed gear ( to a certain extent ). As such, a 6 ohm nominal impedance may be too low for most OTL's, even though the Atma's are nice amps. I say this because most speakers that are "nominally rated" at 6 ohms will typically dip to 4 ohms or less. The "nominal" rating simply means that the average impedance "balances out" to the rated figure, taking into consideration the various peaks and dips involved.
Other than that, you might want to look at the availability of any tube that you'll be using. Are there lots available? Different brands to experiment with? What do they cost to replace? How hard is it to convert the unit from one type of tube to another? All of this comes into play if you intend on keeping these amps for an extended amount of time. Sean
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If you look at the power output on most OTL's, you'll find that their power output actually goes UP as impedance climbs, which is the exact opposite of SS and most tubed gear ( to a certain extent ). As such, a 6 ohm nominal impedance may be too low for most OTL's, even though the Atma's are nice amps. I say this because most speakers that are "nominally rated" at 6 ohms will typically dip to 4 ohms or less. The "nominal" rating simply means that the average impedance "balances out" to the rated figure, taking into consideration the various peaks and dips involved.
Other than that, you might want to look at the availability of any tube that you'll be using. Are there lots available? Different brands to experiment with? What do they cost to replace? How hard is it to convert the unit from one type of tube to another? All of this comes into play if you intend on keeping these amps for an extended amount of time. Sean
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