Bottlehead Forum

Welcome! Need support, you got it. Or share you ideas and experiences.

Return to Bottlehead Forum

Bottlehead Forum

Re: Well, just one fool's opinion...

162.84.152.76

[ Follow Ups ] [ Post Followup ] [ Thread: Display Email ] [ Bottlehead Forum ] [ FAQ ]

In Reply to: Well, just one fool's opinion... posted by Phil Sieg on February 28, 2002 at 15:35:54:

Phil,
Correct me if I am wrong but, it seems like the problem with most OTL's out there is that the output stage topology is basically paralleling a bunch of triodes in order to lower the output impedance. SET's on the other hand and even Push/Pull SET's like the Amity are unique in that they have ONE or at most TWO output DHT's. This gives a sense of detail as well as dynamics which is harder to achieve in OTL's. It also can be used with just as many varieties of speakers. A 45 for example is comfortable with 103dB speakers while a PP DHT like Amity is comfortable with 90dB+ speakers. I am not entirely sure if it is necessarily true that power corrupts although that is a tough argument to beat when you hear a 45 Cobalt Parafeed SET feeding a pair of ORIS horns. But thank you for stating your favorite topologies, that is definitely an interesting way of looking at it.
AnandR.

Follow Ups:

Re: Well, just one fool's opinion... - Phil Sieg 18:17:02 02/28/02 (1)
Correct me if I am wrong but, it seems like the problem with most OTL's out there is that the output stage topology is basically paralleling a bunch of triodes in order to lower the output impedance.
Correct. And you are also paralleling those same output devices to achieve more power. The problem is that the internal resistance and capacitance of the tubes varies with age (and construction) and plays hob with the time constants. The result is a smearing effect in which the low-level detail (that I think is essential to communicate the concept of real people making music in real time in a real place.
SET's on the other hand and even Push/Pull SET's like the Amity are unique in that they have ONE or at most TWO output DHT's
Obviously, one could construct a PPDHT amp with as many pairs of output tubes as needed to achieve the power requirement. But no one does. So given the single output stage construction, you get some advantages of SE with the harmonic distortion cancellation of PP. Take it one step further to a parafeed output and you can then switch to bridged SE with the same harmonic cancellation benefits and still have an SE output.
I am not entirely sure if it is necessarily true that power corrupts
Allow me to put it another way. More power than the speakers require corrupts. For example, the SE211 amp we had at VSAC always sounded too "technicolor". too splashy with loss of detail on my T-1s. But on the speakers that the designer built the amp for (~90dB), the amp is wonderful.
But, in general, on speakers that are efficient enough to be driven by a 45 or 2A3, the higher power triodes (300B, 845 run at 1000V+ on the plate, etc) just don't cut it for me. Yes, they will handle the big stuff like orchestral crescendoes a little better, but they lose the microdynamics and detail. And God is in the detail(s).
- Re: Well, just one fool's opinion... - Phil Sieg 18:20:43 02/28/02 (0)
  The result is a smearing effect in which the low-level detail (that I think is essential to communicate the concept of real people making music in real time in a real place
  OK, close paren and finish the sentence thusly. ")goes missing." Sheesh, Phil.

This post is made possible by the generous support of people like you and our sponsors:

You can not post to an archived thread.