John Curl's Blowtorch preamplifier part II

[scott wurcer]

Hi,

Doesn't non zero phase angle also give less crossover distorsion?

/örjan

Crossover refers to the commutation of current in the output buffer, so it moves but does not necessarily lessen but the phase of all the distortion components becomes modulated. Audible difference, don't know. Certainly worth pursuing as a source of amp/speaker interaction.

 

[bogdan_borko]

Call it what you want: mistake, oversight, whatever. Dave did not realize what he was doing to the speaker impedance curve when he added this added series resonance. Apparently it sounded and measured acoustically better (he used Heyser's TEF in those days) and it did not affect his amps, so he put it in. He was very embarrassed when I pointed out to him that he made a mistake, but he took it well. It took years for him to 'work around' this aberration, and in some ways for the worst. However high current supply amps with limited output protection will drive this load OK, and even tube amps do OK with it. They apparently 'ignore' the dropout.

Speaker designer of very high price products did`t measure such a basic stuff as the speaker impedance...That tells a lot. Ok, people make mistakes, but this example is silly...I could understand that if he was selling 200$ a pair speakers made in China, or something like that...

 

[john curl]

Bogdan you remind me of those who used to give me a hard time about the cost of making the CTC Blowtorch. It appears to be beyond you that the cabinet is VERY COSTLY to make, just like it was for us to make the aluminum cases for the CTC Blowtorch that cost us about $3000, 15 years ago. Criticism is easy, perfection is not.

 

[dvv]

Call it what you want: mistake, oversight, whatever. Dave did not realize what he was doing to the speaker impedance curve when he added this added series resonance. Apparently it sounded and measured acoustically better (he used Heyser's TEF in those days) and it did not affect his amps, so he put it in. He was very embarrassed when I pointed out to him that he made a mistake, but he took it well. It took years for him to 'work around' this aberration, and in some ways for the worst. However high current supply amps with limited output protection will drive this load OK, and even tube amps do OK with it. They apparently 'ignore' the dropout.

These aggressive protection schemes cuased a lot of grief in the late 70-ies. Far too many amps, typically from mnufacturers' top f the line ranges, were pished so hard by the undying Japanese drive to use SEPP output stages in high power amplification that their protection circuits had to be aggressive. They still offer models rated at 100/200W into 8/4 Ohms using just one pair of 150W devices. That just sounds hunny and flat when connected to a sdeaker with a funny impedance modulus.

 

[bogdan_borko]

Bogdan you remind me of those who used to give me a hard time about the cost of making the CTC Blowtorch. It appears to be beyond you that the cabinet is VERY COSTLY to make, just like it was for us to make the aluminum cases for the CTC Blowtorch that cost us about $3000, 15 years ago. Criticism is easy, perfection is not.

Ok, let me correct my self:

Speaker designer did`t measure such a basic stuff as the speaker impedance?

 

[john curl]

Impedance is a separate measurement. He just was not looking there.

 

[bogdan_borko]

Impedance is a separate measurement. He just was not looking there.

"Impedance is a separate measurement." Thanks for letting us learn new things

 

[Bonsai]

That's a good enough reason to stick with B&W. All that basic stuff is attended to and you get performsnce on the 802's that one reviewer described as 'a speaker that swats 5 and 6 K $ speakers away as if they were gnats' or words to that effect.

 

[john curl]

Sound quality is a subjective thing, I like WATT's.

 

[billshurv]

Original WATTs can be forgiven. They were not designed as a production monitor just people asked to buy them. This was what, 35 years ago? Likewise the WAMM, back then no one expected $100k speakers to sell and they ended up selling around 100 sets before.

 

[Pano]

Double stacked ESL 57 will separate the amplifier wheat from the chaff. Difficult load and doesn't audibly mask much.

 

[john curl]

You are correct, billshurv. For the record, the WAMM was VERY kludge like. BUT it worked! It could sound wonderful. My friends and I used to go over to Dave's house (in the bay area) in the 1980's to have a listening party. It was wonderful!
Dave tried everything, and he was not prejudiced by an engineering degree on what not to do. He has a degree in biology or something, instead. You know, professional but not really technical.

 

[john curl]

I would agree. But a very different kind of load.

 

[Pano]

True, and fortunately not very common.

 

[scott wurcer]

he was not prejudiced by an engineering degree on what not to do. .

Alchemists were not prejudiced by science either.

 

[john curl]

Paul Klipsch forever! '-)

 

[scott wurcer]

Paul Klipsch forever! '-)

And 5 (all you ever need) Watt amplifiers.

 

[Chris Hornbeck]

Paul once observed that if you could make a speaker 100% efficient it would have a perfectly flat frequency response. Not really true, but fun.

Thanks, as always,
Chris

 

[dvv]

Still, I fondly preserve memories of auditioning his Heresy speakers in the late 70ies. Reminded me of Monty Python's memorable line: "And now, for something completely different".

 

[Bonsai]

While in Japan I heard a pair of the big Tannoy's (you know the ones that look like they belong in some whiskey and cigar gentleman's club, Pall Mall, London). Wow, what a sound - fantastic imaging. I think they were being driven by a luxman amp. Quite expensive though - about 10 big ones IIRC.