Hashimoto

Hi Al. The setup is currently 3 way, so I have the strap removed on the AP-12s and the "high out" terminals going to the "biamp" connections on the universal networks, where the 902s and Beymas are connected. I included the 3619s on the AP-12s because I would like to try them as a simple two way with the 902s at some point, but they are not presently used. A couple of questions for you: my 902s have 16 ohm diaphragms. How much does this change the impedance of the network? I have also simply observed the polarity of the squawker and tweeter connections at the terminals of the universal networks. Do they need to be reversed?

another pic of the AP-12 with the universals

Here are pics of my DIY AP-12 600 crossovers built from Al's design. Every one of Al's upgrades to my Belles have improved the sound, starting with his universal crossovers, then Trachorns, now the AP-12s with GPA 902s and Beyma tweeters, using the universals as the squawker/tweeter network. Al always promptly and patiently answered all my questions. Thanks, Al.

An SS amp made from bipolar devices and using Class B push-pull topology will create lots of odd-order harmonics when clipping. Any amplifier that tries to output more than the power supply can provide will clip, tube or SS. Symmetrical clipping causes the odd-order harmonics that sound bad. Circuits that employ transconductance devices (tubes, FETs, MOSFETs) may be easily configured to run in Class A, thus reducing high levels of odd harmonics. See the Pass Labs website for complete info. Not always. And there is no reason that SS cannot use an output transformer. Macintosh gear has used autoformers, in the past if not currently. Only when used in switching circuits (digital) There should be none of the core saturation that must occur for what you described in a properly functioning analog circuit. Amplifier circuitry, SS included, may be designed for large amounts of headroom by using an oversized power supply without stiff regulation, among other ways. There are SS audio amps capable of over 1KW peaks on the market. How many tubers can do that? Quick reply: Don, go back to the textbooks. Any transformer coupled stage, tube or SS, analog or digital, input, voltage, driver, or output, is using the stored energy of the inductor (the inductance) to swing the signal. That's how the topology works. The output tube clips only when driven to grid cutoff on the positive swing or the onset of grid current when the grid goes positive. It's a question of bias. Yes, the transformer core can saturate when the voltage swing is greater than the core is designed to handle. BTW, pulse transformers are generally used to galvanically isolate one stage from the next. The way the amp clips depends on the topology, including whatever class it's run in, whether there is feedback or not, how that feedback is applied, how the devices are biased, how they are coupled, etc.

Don, not BS. A SS amp output stage is limited by the supply rails so the clipping behaviour is really nasty. The output tube on a tube amp is working into an output transformer. It's basic electronics: an inductor stores energy and can swing way above B+. Clipping behaviour in a tube amp depends on many factors, such as the amount of negative feedback used. In addition, with triodes in the output stage, the tube can draw grid current when the grid is driven positive to provide extra power. It's called Class A2. If there is sufficient headroom in the voltage amp/driver stages, the peak power that a tube amp can supply is quite amazing.

6S4A transformer coupled to a 300B, monoblocs, my design, on breadboards until I finish tweaking them. I'm very impressed with transformer coupling. Thanks for asking.

Got the ALKs on Monday, bypassed the fuse on the woofer (hope Al doesn't mind, running 300B SETs so not worried about blowing the woofer) and finally hooked them up last night, replacing the stock AB-2s. Very nice improvement, better clarity and definition, smoother response, really brought the mids forward nicely. The Beyma CP25s may be a bit too hot, but not objectionably so. Great product, nicely built. Can't wait to get the Trachorns. Thanks again, Al.

Just an addendum: icing can be negated, in the NHL, if a player from the team responsible for the icing touches the puck first.

That was one of the worst games the Wings have played in the playoffs. I don't whether the ice was bad or what, but they seemed a little lacklustre and their passing/puck control wasn't very good. And they still managed to win. WIngs in 6.

Thanks, Tom. That's pretty much the conclusion I came to. I ordered a pair from Al yesterday. Saving up for the Trachorns...[8-|]

Modified Bottlehead Parabees. Constant current DC filament supplies for the 300Bs. Shunt regulated CCS loaded driver stage. I also integrated them, i.e. they have stepped attenuators at the input. It wouldn't all fit into the original tiny chassis so they're on breadboards for now. Source is an ARC CD3 balanced out into Burson balanced in single-ended out buffer into the amps. Have some IT coupled SETs half-finished on the bench.

Yes, my first Klipsches. 35 years ago in high school, my best friend's father had a Macintosh amp, Dual TT and Heresies in his basement. We would rock out. Once I got the toe-in in the ballpark, they came together very nicely. Good recordings are wonderful, especially recently remastered stuff. Older CDs can be a bit hard. For example: Beatles White Album on CD, "Blackbird" was terrific. I have never heard the separation of Paul's voice and whoever sings with him in the chorus so clearly before. "Back in the USSR" had me scrambling to turn it down, hard and screechy. So a bit Jekyll and Hyde, mostly Jekyll. I'll listen for a while but I'm already thinking crossover upgrade, constant impedance ones like the ALKs as I'm using SET amps.

The other one. S/N 143292494-5.

Got them yesterday. Very nice. These'll be with me for a while.

Just got my 1992 Belles. Haven't played with them much yet but they sound pretty nice, imaging being the biggest issue at the moment. They have the AB-2 crossovers. Would someone be able to run over the various crossover options/upgrades available? Yes, I have spent hours searching the archives. A concise summary would be nice... :-) Yes, I will post pics soon. Thanks.