Watt Sucking Fireball Series

[kenpeter]

Where one sees linear voltage swings, you rarely see linear current swing.
Into a gate of a MOSFET one really prime example... And with linear current
swing into, oh say a loudspeaker, rarely you will see linear voltage. They just
do not work hand in hand together like that unless source and load impedance
is an absolute match. One factor has to hold the line, the other has to work
the load.

There is nothing invalid about voltage wildly all over the place and non-linear,
as long as current swing is holding true to the line, and vice-versa. I do not
think you can realistically hope to achieve sumaudio's linearity everywhere
paradigm without impossibly good impedance match everywhere.

And those who follow RF, know that lowest noise figure rarely coincides with
impedance match. I suspect a wild goose chase to achieve "the paradigm"
would only introduce other problems. But every reasonable thought outside
our too well traveled box brings the chance of advancing the art. Shouldn't
abandon the quest on my skepticism.

[sumaudioguy]

Whatever was written is a design philosophy. It is not a blind vision to all other thoughts and possibilities.

kenpeter has hit on a key point, impedance matching can solve many problems when it is available. Obviously impedance matching is not the goal for voltage source audio power amplification at the output as that is defined as a voltage source. No impedance match there. On the other hand, circuits inside the amplifier can be "defined" and topologies devised such that the voltage source output result appears as the filter with gain as mentioned within the current limits of the voltage source. Very few audio amplifiers have stable filter characteristics or transfer function. It is my belief there would be little difference in the performance and sound of various design and smoking an amplifier would not be so incredibly easy as it has proved many times over if this were not true. My amplifiers are all stable and blow the line fuse as protection. Stable filter characteristics and linear response at every stage was the key to that stability. No output load control, no output RC network, no hash choke, no Leech type (which is the proper single slope protection) current limiter, nothing but absolutely stable operation. This was not done with an extraordinary number of output devices either, 4 for the 120watt/8 ohm 350watt/2ohm and 16 for a 420watt/8ohm 1350/2ohm amps. All have this same feature, the line fuse is the short circuit and over current protection. Since learning how to make a stable amplifier I have never looked back.

You may wish to look at this as a chip example...
So just how "good" can a chip amp be ?

For low noise RF have been transformering up the 188 ohm balanced output Z of the receiving antenna to match into the about 800 ohms available with a low noise GAsFet. Is that what you mean? It is not important to answer that.

I am excited to say one of these days there will be a post here with my own watt sucking fireball amp. 300 watts in makes maybe 25 out...oh boy!

[Roadbagger]

Finishing the construction and testing of the WattSuckingFireball#5. Were that all will go as theory and practice would incline, then P-Channel JFets and a new form of complimentary output stage will be in presentation this year. The hardest part of course being the stereo input step attenuator...........90 resistors.........It's Input stage features LSK389's LSK170's and LSJ74's this year

[eyoung]

OH MY!!! I can not Wait
no really

Elwood

[Chad]

Roadbagger,

Am I reading this right, you have have some linear lsj74's? If so how do they stack up to the real 2sj74. I didn't know the released then yet or did you get samples?

Chad

[paul n]

Linear Integrated Systems in conjuction with The Burning Amp Festival is offering pre sale of the new Limited Edition, Linear Systems 2010 Burning Amp Tee Shirts which feature "Watt Sucking FireBall #5"

The Tee Shirts are available in Black in sizes S, M, L, XL, XXL, for a price of $15.00. A good opportunity to guarantee you get the correct size and quantity you want now versus a more limited supply at the show. Your order can be placed thru the LIS website using a credit card. Please provide the size and number of shirts you want along with a phone number. LIS will contact you to confirm your order and recieve your credit card information (A/M, M/C, Visa) You pick up your shirts at the show. Non-show tee shirt sales will be conducted after the show based upon any remaining stock and sizes.

Tee Shirt Design: SlicART Sportswear

Tee Shirt Ordering: Linear Integrated Systems - Contact Us/Support
800-359-4023

Paul Norton
Linear Integrated Systems

[Roadbagger]

Linear Systems will be sampling the LSJ74's at the show. The WSF #5 is a design example of an Amp built around a John Curl-esque front end using these parts

[Roadbagger]

To run this Amp a fair amount of filter capacity is provided in its power supply producing little low frequency load distortion at high peaks. The power supply design is borrowed from last years amp but with additional stepped regulation for the preamp and front end drive. Liberal use of LS duals are in place strictly to minimize non-linearities in the audio current gain path. Though excessive, the TIM is much improved over a simpler Gm stage. Parts used in this Amplifier design are in current manufacture unlike some that were used in the 2009 WSF#4............As usual.................Kirkwood

[Roadbagger]

The good part is that we've been married so long that this seems normal. DIY can potentially move into areas of concern, but where else does the creative process flourish, but where pie and coffee come from?

[scott wurcer]

Still looking for couple of LSJ74's