Curious_George

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You mean… “they put on their Depends, the same as as anyone else…”

I’m a firm believer in the Coriolis Effect making a huge difference in sound. Obviously, the Northern Hemisphere sounds better than the Southern Hemisphere.

I used an 80uF cap in the woofer circuit to roll off the woofer a bit faster. This improved the transition from woofer to midrange for me in my Lascala. Two 100uF = 200uF, which would be too much. Try 80uF.

As an alternative to the Crites A4500 network, we can build on the AA network and modify it to use an 18dB/octave filter at 4500Hz (vs the 6dB/octave filter at 4500Hz on the Crites network). The below schematic has not been built or tested by me, but only offered as a starting point for people like Geoff to experiment with. If any type of tweeter attenuation is needed, you cannot use a T2A autotransformer tap. You will need to use an adjustable or fixed type L-pad. 2.7uF and 8.2uF values can be used for the capacitors. The values on the schematic are calculated values. The diodes are optional and I only showed them because they are included on the OE AA network.

Big Ugly Super Horn

I have been experimenting with this horn / waveguide. It is inexpensive and sounds very good. I’m going to incorporate them with the ZXPC 18x10 horn when I redo my LaScala’s with a separate top section. Dayton Audio - H07E 6%22 x 6%22 Elliptical Waveguide 1%22 Threaded.pdf

Exactly. At 500V your choices are limited and price goes up fast.

For those interested, I use Vishay-Dale CMF and / or TKD CM2 series resistors for signal. For other areas, low inductance wire wounds are used. Coupling caps are Orange Drop 715P 400V series.

Plus, I like the slow warm up of the indirectly heated rectifiers. I have 5R4, 5U4 and 5Y3GT too and use them as well.

i usually use a JJ GZ34/5AR4 or USA NOS 5V4GA. The JJ seem to be decent quality for the price. They were $15 recently, now they are $20. I also like the 5Z4, but it is metal, so not too good looking, if that is a concern.

I apologise. I had “A” on the brain.

Switch the two 2uF's for two 4uF's and add the 500uH coil.

I was not aware of that.

You can't just drop the tweeter crossover point to 4500Hz. You have to change BOTH the midrange lowpass and tweeter highpass crossover points. The below image contains the changes you need to make;

The "coil" was added by Bob in his A4500 design. It is not part of a stock AA crossover.

In order to use a modified AA at 4500Hz, you will need to use a different tweeter than the K77, but you probably already know that. Just FYI.

The "A" crossover is one capacitor, 6dB/octave. The "AA" crossover is two caps & coil, 18dB/octave + back to back Zener diodes for "more" tweeter protection.

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After this amp build, I’m going to experiment with another amp and ensure I have “low frequency boost” and increase / decrease power supply capacitance and see how this affects things.

I have not fully investigated the phenomenon, but for example, if I use a large bypass cap on a 2A3 amp with a 750 ohm cathode resistor and let’s say 100uF cap, I’ll get a low frequency boost on the low end. This has happened on Lundahls, Hammonds, Edcor and James transformers. The “boost” is slightly different on each transformer. I discovered I can flatten the response by using a smaller cathode cap by trial and error.

I don’t have a complete BOM, but can put one together.

Thank you for your kind comments. Lately, this layout seems to be a good aesthetic. I figure most people want to see the big power triodes and hiding the rectifier enhances the front 4 tubes. I like to add a front pilot light because in daylight conditions, it is hard to tell if the amp is on.

I guess this falls under “observation”.