John Curl's Blowtorch preamplifier part II

[john curl]

No, Morinix, 1969 was the year that I was first told by my guru, Richard Heyser, the 'secret' to successful amplifier design. '-) The following years and meetings with other 'prophets' like Matti Otala, Walt Jung, Malcolm Hawksford, etc have allowed me to continue on my journey to learn to make the best audio designs possible.

[dimitri]

It change the Thiele and Small parameters(speakers+motional compensation QTS.)

Christophe, are you talking about something like this?

[gk7]

Originally Posted by Esperado

the Fs and air volume remain the same, so , believe the vents will resonate at the same frequency ?
I have always used-it with a well tuned enclosure ( equal impedance peaks around fr )so i don't know how it turn when it is not. I believe the resulting impedance curve will not be as flat.

If you change the TSP parameters (although I cannot see how this would be
the case) the alignment changes (There is more to it than just fs and air volume).
Additionally "equal impedance peaks around fr" by no means do assure a maximally
flat alignment.
I really would like to see some measurements with and without this impendance eq (same enclosure, same driver).

[gk7]

Of course, if you alter the impedance curve by some network and then measure the
TSPs the usual way (deriving them from the impedance curve) by using a current (or
reasonably large resistor) you just have messed up your TSP measurement.
These "new" TSPs have no relationship to the drivers TSP when driven from a low impedance
source (amplifier).

[Esperado]

Originally Posted by dimitri

Christophe, are you talking about something like this?

You got-it !

I feel quite uncomfortable, here, after this strange controversy about horns and this motional compensation.. Obliged to argue like if i had something to sell or promote (including myself).
I do not care about people's opinions on my personal speakers, or even myself.

Just i had myself, and during decades, a very bad opinion about horns, both because my PA experience, and all those poor but loud and aggressive studio monitors i was obliged to work with.

One day, a friend of mine, François Delamare asked-me to go in his workshop to listen to his last enclosure, with some excitation in the voice. Because this guy knows what he is talking about, i ran in his place to listen to what will be the Aeria system.
I was surprised by the form of those horns, never seen before at this time (it was before the Lecleach work). We listened 4 hours, on a good system (amps etc...) and i was...astonished.

Never heard in my all life such a natural system, so powerfull, so dynamic, so free,so detailled, with no audible distortion and no resonances neither donald duck effect. Impossible to notice any compression driver or horn. Just the closest sound to real life. We worked together, with known mastering tapes etc... to tune-it to a perfect tonal balance, with a slowly descending curve, strait (very flat) from the basses to the treeble.

End of the story. I had build a reduced version for my own home system with the same horn calculation, then build big ones for my post production mixing facility.

Till this day, i had never heard something more natural, and the revue i had published here reflect exact what i still feel about.

I do not pretend there is no better system somewhere. I just wanted those of you witch never listened to a Lecleach system (not very far from the Delamare one) to discover-it and change their minds about horns. Google for lecleach, there is full of comments like:

Le Cléac’h horns create natural sounding music, with a deep involving sound stage. There are now many more people out there who can attest to this, and signs are that the Le Cleac’h expansion is gaining ascendancy.
I would like to thank Jean-Michel Le Cléac’h for his beautiful curve, given freely to all – and the brave experimenters who kept me going with their encouragement.

It is "Open source" with a strong DIYer community.

[Esperado]

Originally Posted by gk7

Of course, if you alter the impedance curve by some network and then measure....

Let-us be clear.
I am unable to modeling-it. I'm not a theoretician in electro-acoustic.
I agree that, if you flatten the motional impedance of a loudspeaker at free air, when it is charged by a bass reflex, the resonance frequency had changed, so this network will not be at the good frequency, so you will expect some up and down in the impedance curve.
But, as astonishing it can be, it is not as-it.
It works. Try-it by yourself, please, as i have done-it hundred times... or forget.

Of course, it will be more precise to measure your speaker in your vented box, then provide two networks for each peak around the resonance. You double the work as well as the price of the expensive inductances and caps.
No need, as, believe-me, please, it works all the time by the way i indicate.

I will try to provide-you some real curves, please be patient.

[scott wurcer]

Originally Posted by john curl

No, Morinix, 1969 was the year that I was first told by my guru, Richard Heyser, the 'secret' to successful amplifier design. '-) The following years and meetings with other 'prophets' like Matti Otala, Walt Jung, Malcolm Hawksford, etc have allowed me to continue on my journey to learn to make the best audio designs possible.

In 1969 I had a pair of DIY David Weems' "Wild Woofers" and Dyna MKIII's ($60 as kit). An AR TT with M91E was standard for the day.

[SY]

I hope you had some Koss Pro4AAs to go with that!

[RNMarsh]

Confessions: I had an all JBL... home made 3-way horn system, home made tube preamp from wireless world and a home made Dyna amp with super fidelity output transformers. Sourced via a Sony reel to reel and a Garrard Lab 80 turntable with M91E or Stanton 681. And, the PRO 4AA. and a Marantz 20 with scope (ss) for a tuner. And discrete Dolby NR from Advent. Hard core all the way :-)

[john curl]

In 1969, I had a K-horn, driven by Dyna Mk3 at first, then I tried the first solid state Marantz, the Model 14, then after getting listener fatigue, I went back to the Dyna Mk3. Also Dyna Pas3X tube preamp, Ampex AG-500 pro 15'' recorder, Beyer DT-48S headphones, TD150 turntable with Ortofon moving coil cartridge and transformer.