Anyone rolled their own simul class power section?

[Bear]

For the legally squeamish, I gather that it's nigh impossible to violate the patent since the actual Boogie products on the market don't meet the patent description.

[gingertube]

And Randall Smith copied the design right out of Radiotron Designers Handbook anyway. One of his spurious patents which shows nothing, except possibly about his character, and that the US Patent Office doesn't bother to check anything.

The "design" is NOT his and the patent is un-enforcable. The schematic drawings I have seen have a deliberate? error anyway, perhaps to discourage anyone from copying his copying. Use the design with impunity.

Another variation, Ultralinear + Triode Mode is a common modification done to Fender Twins to "warm" them up a bit, by triode strapping one output pair.

Cheers,
Ian

[katopan]

And unless it was commercial who'd know anyway???

[Bear]

Back to the RDH, then. (But it's so damned heavy!)

At SLO Clones, some are of the theory that Boogie used undersized output iron for their 2:90, something like a Marshall 50 watt OT but with a slightly bigger lam stack. They've measured the taps as indiscernible from standard P-P iron.

[Colossal]

Check out Richard Kuehnel's take on SimulClass:

http://www.ampbooks.com/home/amp-techno ... t-7173488/

[funkmeblue]

the above link actually has nothing to do with simulclass. Simulclass requires 4 tubes.....2 tubes in class ab push pull and 2 tubes sometimes triode and sometimes ultralinear biased to puch pull class a

[roberto]

We have also the winding diagrams on sloclones.
There's nothing special on the OT, and only 2:90 has smaller OTs.
The configuration is on the polarization of one pair of tubes in "triode" mode and with a voltage divider on both signal and bias.

[Colossal]

the above link actually has nothing to do with simulclass. Simulclass requires 4 tubes.....2 tubes in class ab push pull and 2 tubes sometimes triode and sometimes ultralinear biased to push pull class a

Sure, but the point of his article (and why I posted the link) was to address the justification for the patent and define and go beyond the class switch to a continuously variable mode already in previous art. So it's the mechanism I think Kuehnel was talking about with "...at minimum we effectively short the audio for one phase, just like Mesa Boogie's switch" being the result as well as providing a subtle dig at Smith's proclivity to apply for (and the patent office's willingness to grant) patents which are common sense reapplications of existing design.

Rectifier switch patent? Really? C'mon, that's like patenting a physical key and a IR remote as SimulClass Entry(TM) and telling all the other auto manufacturers they need to find some other way to open their vehicles.

[katopan]

Rectifier switch patent? Really? C'mon......

Makes me so angry the whole patent thing esp with Randall Smith. When you search and read through what he's got past the keeper he might as well have patented "musical instrument amplification device" and covered the lot in one hit. And then told everyone else they can't build anything anymore because they will be in violation.

Was reading up on various SS tube emulation patents a while ago and if you take their general 'this covers everything' type of clauses there are a few that look to be very similar and they got past the keeper too.

[ampdoc1]

No simul-class,....Randall's an ass-hole of the first class. When I did repairs in the 80s and 90s, I hated to work on the Boogies. No full schematics even for Mesa "certified" techs, crowded PCBs, and miserable warranty repair rates.

And while I knew a lot of Mesa players that sounded terrific, personally I thought they all felt "stiff".

Fuck him and the (cl)ass he rode in on.

[roberto]

And while I knew a lot of Mesa players that sounded terrific, personally I thought they all felt "stiff".

I absolutely agree. But slightly mod their amp and they will play even better than before.

[jaysg]

You might go straight to Heyboer with this. Simul-class sounded like a good idea at the time, but is it all that? After all this time, it's not something others are doing. Patents only last an average of 17 years after approval, since the startup is included in the time. Isn't it out now?

[Bear]

I'm really just trying to get related-ish feedback to gather ideas. At some point I'm going to get around to building a dedicated power amp for my Boogie Quad preamp, so probing what to appropriate from a Simul Class (but at lower power output) was kind of natural.

I'm playing with the idea of doing a mash-up of Dumble and Boogie ideas but using noval Russian power tubes for the cheapness and because I have very modest power needs. So PI with CF's afterwards, SSS style, driving one pair of 6p1p-ev's in normal tetrode wiring fixed bias and maybe some triode strapped 6p14p's cathode biased, both pairs feeding a upgrade DR output transformer, like an Allen TO-26. Probably wouldn't add up to anything as fantastic as one could hope, but it'd be a relatively cheap folly and a platform for trying some ideas out afterwards.