SLAPS for bass.

[Circlomanen]

I will still build three pairs of amplifiers of each device.

Just saying that I am impressed is an understatement!!!

Your competence and your drive to build these amps (and your speakers) is very impressive and very inspiring!!!

I might find out that a SLAPS for SLAM! with the JFET measures quite well.

I am sorry for my rather youthful use of emojis, but this is like Christmas time for me when I was 10 years old.

I would guess that these SIC JFETs would tend to sound very smooth, low grain, refined and organic compared to normal IRFPXXX mosfets if used correctly. That is my previous experience with SIC mosfets at least.

 

[solhaga]

Thank you, Circlomanen!
But as i see it, I just follow your lead.

Apart from comparing the SQ, there are also the thermal runaway trait of the MOSFETs to consider.
I often see that MOSFETs legs "steal" the current after several minutes and thus gets very hot. I fear that they will break down with time.

The JFET amplifier stabilizes within a couple minutes.
It is also easier to match the JFETs at the correct Is.

Buy the way, did I get this right?

An externally hosted image should be here but it was not working when we last tested it.

 

[Circlomanen]

You have to connect R2 to the junction between C1 and C2 plus battery.

You want to use the battery to set the DC voltage at the gates of the JFETs at minus 9,3 volts or so.

 

[solhaga]

Like this then:

An externally hosted image should be here but it was not working when we last tested it.

Could the battery be 12V?

 

[solhaga]

It is easier and quicker to find the optimum source resistors/bias with a guitar of kanthal wire:

 

[Circlomanen]

You have officially made guitar tuning an accepted method of optimizing amplifier designs!!

LTSPICE, guitar tuning and listening tests - all work in a concerted way to bring out maximum of sound quality from the SLAPs design.


I am very impressed by your ingenuity!

 

[solhaga]

Yes, and when I'm done I can use it as a bread toaster.

 

[solhaga]

Playing SLAPS

So finally I hooked up the SLAPS amplifiers instead of the Trimodals.

The three pairs of SLAPS for bass has three different transistors implemented:
IRFP150, IRFPS3810 and SiC UJ3N065080K3S.

I thought I later evaluate the three pairs only driving the woofers and then implement the winner transistors in all six SLAPS for bass.

 

[marconi118]

what is the advantage of SLAPS compared to MoFo? maybe just a bit of gain?

 

[solhaga]

I don't know that much of the MoFo other than it is as simple as SLAPS (apart from the actual SLAPS coil of course).
What's the best distortion levels of any MoFo incarnation?

SLAPS has a gain of two.

 

[Circlomanen]

what is the advantage of SLAPS

The two floating out of phase (balanced) outputs will keep the currents from the loudspeaker out from the groundplane, there by creating a nice stable electrical enviroment within the amp and power supply. Most amps behave nicely when driving a resistive load with simple sine waves but fail misserably when driving highly reactive loads with complex non-sinusoidal wave shapes.

The SLAPS has a feed forward error correction of sorts as a distorsion lowering mechanism. I prefer the sonic character of feed forward error correction to negativ feedback when driving reactive real life loads with complex real world signal.

 

[marconi118]

doesn't the MoFo use a feed forward error correction too?
But gain is 0.99