John Curl's Blowtorch preamplifier part II

Status
Not open for further replies.
Disabled Account
Joined 2012
No doubts

So Mr. Marsh, I don't only design teeny speakers without bass. :D

I had no doubts that you could do so if you tried (and you have). but it doesnt help me if the speakers are in a church. What can I buy that works without costing the entire earths wealth?
Right now, I have a pair of TC-Sounds 5400 Ultra drivers (18") waiting for winter project time to arrive (soon). Thx-RNM
 
I had no doubts that you could do so if you tried (and you have). but it doesnt help me if the speakers are in a church. What can I buy that works without costing the entire earths wealth?
Right now, I have a pair of TC-Sounds 5400 Ultra drivers (18") waiting for winter project time to arrive (soon). Thx-RNM

Did you insure your house already for an earthquake? ;)
 
What can I buy that works without costing the entire earths wealth?
More than 10 yrs is a long time to be out of the game so I don't know. Speakers are very personal so what you like is more important than what ANYONE ELSE says.

Do you use & like your ELS63s these days? Perhaps try some of the specialist Dipole subs for it. Very sad that this millenium, very few shops have good demo facilities and even fewer will let you take speakers home for a day or two on approval.

I'm glad you don't subscribe to the false "one sub is good enough" philosophy.

It's a bit too late but the big 18" units will require a HUGE box to perform well; probably best wall mounted. If the same magnet & motor was on a 12" unit, you could get the same performance from a much smaller box. Thiele & Small were academics so their stuff tends to hide these useful tidbits.

The organ sub was 2x10" units in a 90 ltr box which amazed the organ builders who had used much bigger boxes & units from other makers with worse results. But the magnets were off 15" high power units so nearly as big as the little cone. :eek: It's a power/weight thing .. similar to horns but I better shut up or John will .... mmm..ph!
 
This is the CTC Blowtorch preamp:
 

Attachments

  • ctc blowtorch open.jpg
    ctc blowtorch open.jpg
    99 KB · Views: 167
  • 1302013687.jpg
    1302013687.jpg
    43 KB · Views: 165
Did-you tried constant impedance resistance arrays to get rid of potentiometers ?

I'm might be not right person to answer this or any other questions on this forum, but somewhere in the 29000+ letters of this thread buried a short discusion about volume controls and among others John Curl contributed his views to. If I remember correctly he said, and this is not a quote: he first preferred wire wound volume controls for his home system, but later changed to something other, the rest I don't remember (you really need a team to find anything in a thread like this). I wouldn't be able to buy it anyway, but you can be sure that pot in the Blowtorch is a good one. After all this amp is carved out of a big block of aluminum with tender loving care and cost no object.:sax:
 
Disabled Account
Joined 2012
Long before Vol 4 of Linear Audio came out, i said here that there was plenty of reason to think very low distortion was audible. I did my own distortion threshold tests and found that we needed AT LEAST .01% was max distortion to design for. And because we listen to a whole system, we needed products with -100db or better in each so the total of the entire system was below threshold. Well, Vol 4 shows even lower thresholds are detectable. This puts a new light on things... about our equipment and about listening tests.

Part of this is what we started to talk about earlier... JC has been very aware and designs with harmonics weighting towards the higher harmonics being more important and more detectable.

I would like JC to talk more about his designs and what/how they were developed with this in mind. Thx-RNMarsh
 
Last edited:
"Part of this is what we started to talk about earlier... JC has been very aware and designs with harmonics weighting towards the higher harmonics being more important and more detectable.

I would like JC to talk more about his designs and what/how they were developed with this in mind. Thx-RNMarsh"

That would be great!
 
I did my own distortion threshold tests and found that we needed AT LEAST .01% was max distortion to design for. And because we listen to a whole system, we needed products with -100db or better
How can-you explain we can afford a distortion of loudspeakers (for the best of them) at -50db (0.2%), in the same time ?
I believe harmonic distortion is not such a big problem, as it change only the tonal composition of the instruments and sound sources in a very natural way. I worry much more about IM, as it adds other sounds, not correlated at all, bringing confusion between sources.
 
Last edited:
Status
Not open for further replies.