@SemiSouthFan,
Great article, thanks a lot. I feel sorry for you that such a great idea does not sell in speed, hence, you experienced all the misery.
May I kindly ask you -as soon as you find something similar with these SemiSouth devices- to keep this thread alive? Would be lovely.
Thanks @ Cheerio,
Navelpluis
Great article, thanks a lot. I feel sorry for you that such a great idea does not sell in speed, hence, you experienced all the misery.
May I kindly ask you -as soon as you find something similar with these SemiSouth devices- to keep this thread alive? Would be lovely.
Thanks @ Cheerio,
Navelpluis
As you may already know, JFETs have what is known as 1/f noise, and this
noise is apparent in these devices, enough that I select the SITs for noise
when using them as power amplifier outputs.
If used in preamps, you would likely want to enclose them in a feedback
loop to get the noise down.
I can't imagine what you could do with them in an audio application.
If they sound that bad in a guitar amplifier, they're going to sound much worse in a "hi-fi" application.
There is a lot of tolerance/allowance for asymmetry, mis-biasing, crossover, and clipping distortion in guitar amps, but that module didn't sound good any way you look at it.
@Zen, I've been playing guitar and listening to guitar amps 35+ years; I can indeed HEAR the difference.
Hello Zen Mod, and poynt99. I have on my workbench a prototype amp which conforms to, and broadens the basic approach used by Dr. Mazzola. I'll post soon its details in the dormant thread entitled Class aP amplification in the Passlabs forum. It sounds hi-fi to my ears; driving a pair of 15 inch guitar [musical instrument] speakers.
Best regards
Labjr,
I like doing things that are unusual and challenging. Though the years I have designed and built many circuits of all types... Not just audio stuff. A lot of those circuits worked and a lot didn't, but the process of design, build, test, and refine is fulfilling to me regardless of whether it makes sense to anyone else. There is nothing like the satisfaction of seeing a circuit come to life for the first time. Simulation has its place, but for me, I would rather work with solder, real components, and unusual things like tube replacement devices....
Antoinel... can't wait to hear more about your new amp. Please let us know here when you have more to tell us.
My guess is the power tubes are geared toward guitar amps, and if they are successful emulating a triode, they could be used for both guitar and Hi-Fi pre-amps.
I think it was accessed through the survey, which is now closed.
What is "drek"?
I repair (and design/build) guitar amps too.
As I recall, the sound quality of the video was decent enough to make a fair A/B comparison. Same recording device, speaker, cabinet, amp, and guitar. It was quite apparent to my ear that the results were night and day between the two "tubes". Don't blame this one on Youtube sound.
Do you need to hear a piece of music live to tell the difference between an oboe and a distorted guitar? I hope you don't.
Hello mikegranger and poynt99. I am on the subject, and hope to post photos, schematics and details during this week in the thread of Class aP amplification.
The last 2 posts in the thread Class aP amplification showed Spice simulations for 2 demonstrator amps. The content of the posts accurately describes the approach used in the proto amp which is spread out on the work bench. It uses two IRFP140 N-Ch Mosfets in the output stage instead of the bjts and the N-SIT depicted in the simulations. Looking ahead, other proto amps will/maybe similarly assembled by using Semisouth's R100 [have; enhancement], R085 [on order; depletion] and 2SJ28 [have; P-SIT]. Cree devices may also be tested.
The last 2 posts in the thread Class aP amplification showed Spice simulations for 2 demonstrator amps. The content of the posts accurately describes the approach used in the proto amp which is spread out on the work bench. It uses two IRFP140 N-Ch Mosfets in the output stage instead of the bjts and the N-SIT depicted in the simulations. Looking ahead, other proto amps will/maybe similarly assembled by using Semisouth's R100 [have; enhancement], R085 [on order; depletion] and 2SJ28 [have; P-SIT]. Cree devices may also be tested.
Thank you all for your continuing interest in the tube replacement concept using SemiSouth JFETs. I'm sorry for not following up sooner. I'm guilty of letting my attention wander to other things, like that day job.
But despite my distractions, my partner has been working on the next revision to the tube replacement product. We have made many improvements. The latest version was played through our Fender Twin reference amp by our guitar amp consultant a week ago. He pronounced the current version "better than the 6L6 tubes." I know that's provocative, but he is an incredible guitar player.
We are now working on the next information dump to share with you all. This will include objective data and a legitimate demonstration with good acoustics. We are also looking to try them in a high-fi "burning amp" soon. We think they will be good for more than just instrument amps. But we'll see!
But despite my distractions, my partner has been working on the next revision to the tube replacement product. We have made many improvements. The latest version was played through our Fender Twin reference amp by our guitar amp consultant a week ago. He pronounced the current version "better than the 6L6 tubes." I know that's provocative, but he is an incredible guitar player.
We are now working on the next information dump to share with you all. This will include objective data and a legitimate demonstration with good acoustics. We are also looking to try them in a high-fi "burning amp" soon. We think they will be good for more than just instrument amps. But we'll see!
Hello labjr. You ask an interesting and a long-standing question; direct versus transformer coupling. Maybe nostalgia, classic designs, a uniqueness in the hearing system of certain audiophiles which mostly appreciates the sound of music from electrons circulating in transformer-coupled power amplifiers. I remember that Crown has [or had] an output transformer in one of its solid-state commercial amps; which led me at the time to ask your same question. I hope that it is therapy and fun [and profitable] to use all of the available devices in our DIY toolkit.
I confess that I am currently dabbling with a transformer-coupled power amplifier. I also hope to assemble a reasonable explanation as to to why.
Regards
Good question. For those that don't crave an amp with tube sockets, your point is well taken. Fortunately, 50 years of solid state amp design has produced magnificent results. For example, I still help people build Pass clones by supplying SemiSouth JFETs.
But there are still folks out there that want and like amplifiers with tube sockets and transformers. For those people, the tube replacement product offers some interesting advantages.
For me, it offers a chance to highlight a feature of the SemiSouth JFET that is not used in the Pass amplifiers, namely their superb voltage rating. A SemiSouth JFET with a 1200 V rating goes as easily into the tube socket vacated by its vacuum electronic cousin as it does in my 24 V F2J.
But there are still folks out there that want and like amplifiers with tube sockets and transformers. For those people, the tube replacement product offers some interesting advantages.
For me, it offers a chance to highlight a feature of the SemiSouth JFET that is not used in the Pass amplifiers, namely their superb voltage rating. A SemiSouth JFET with a 1200 V rating goes as easily into the tube socket vacated by its vacuum electronic cousin as it does in my 24 V F2J.
I understand from a marketing point that the devices themselves have multiple uses. Just can't see using prefab modules for tube type hi-fi amps.
Now guitar amps are a whole 'nother thing all together. Guitarists aren't looking for a straight wire with gain The relationship between tubes, output transformer and speaker creates a desirable sound(basically distortion) that solid state could never get right. I've never heard a solid state guitar amp that I liked.
Now guitar amps are a whole 'nother thing all together. Guitarists aren't looking for a straight wire with gain The relationship between tubes, output transformer and speaker creates a desirable sound(basically distortion) that solid state could never get right. I've never heard a solid state guitar amp that I liked.
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