Which Firstwatt Clone For C&C Abbys

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the subject several times within other threads

GM has posted the essence many times.

Sometimes it works, sometimes it doesn’t. Makes the amplifier look more like a current amplifier. Often used when a low output impedance ampifer with a loudspeaker that prefers an amplifier with higher output impedance.

An example of what happens when you pay attention.


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I sourced PCBs from twitchie, and picked up the SemiSouth parts on eBay. I did a typical build using the deluxe 4u and power supply boards from the store. I went a bit beefy on the transformer (500va) and capacitors (33,000uF) in case they end up being the basis for something else. At least that's what I thought before yesterday :)

I started with a regular F2 build, so I could validate functionality before potentially destroying the SemiSouth parts. I liked the results quite a bit.

Yesterday, I converted to F2J using Papa's notes on the schematic from the Firstwatt site. I re-assembled, re-biased, and carried the amp into the living room. To be honest, I was expecting more of a subtle difference from the conversion. This sounds awesome! I don't see myself going back to my 300B, as this provides the same kind of warmth, texture, and depth to brass and vocals without the poorly controlled bass I recall living with (I haven't used it in about 7 years). If I only listened to Jazz, I don't think I'd need/want anything else.

I see a lot of speaker experiments in my future! Chromenuts, if you wouldn't mind, what drivers and enclosures did you finally stick with and why?

Thanks to all who helped guide these decisions! Thanks Papa! Every time I build one of your designs, I learn, find more music I enjoy, and gain new goals for the hobby. What could be better?
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LOL…Another Happy Customer!!!

Wow…you work fast!

I’ll be honest I don’t think there is a bad fullrange or cabinet with this amp (as long as the design was good to begin with) it just makes them all shine to their fullest.

I’m constantly trying new things.

My latest has been the big Kirishima back horns I posted a pick of earlier in the thread.

I’ve played them with the drivers they came with (206nv) and now my fully modified 206e.

The 206e just continue to catch me off guard…they are remarkably good in so many ways in these horns with these amps.

I still have 208EZ to try with some T90A.

I also ended up with what was supposed to be NOS 206ES-R…but they arrived with some mildew/mold on the cones. I managed to get about half my money back so far…don’t know if I’ll see the rest. I may eventually try to restore and/or modify them.

Relax and enjoy them for a while. Eventually maybe you’ll find something else you want to try.

Screenshot 2023-05-25 at 8.13.24 PM.png

Thanks Chromenuts. I thought the folks in this thread might find this interesting. This is a piece of software I use once I begin to get pleased with how a combination is sounding. It's meant for room correction, and the graph displayed is the amount of correction it needs to apply for flat frequency response. These corrections are then applied via DSP to the PCM directed to the selected output device.

Full disclaimer: I don't like the idea of using DSP's, either :rolleyes: I have found, though, that I like the result of the corrections more than I'm concern with artifacts.

The audible difference is quite pronounced. You can see the software pulling the "shoutiness" out from 1khz -> 3khz. I honestly didn't expect the need to pull back around 70hz -> 90hz. I thought the bottom sounded fine.

Of note is that I haven't added any parallel resistors to the speakers. They're still using the 16R on the F2J board. I wonder if it would sound better if I tuned with resistors first, then took measurements.

Ultimately, I'd like to use the data gathered in this process to tune the new full range equalizer Papa recently, and generously gave us!
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9 foot ceilings, listening about 13' away from the speakers, which are about 9' apart. There are no room treatments, but ample rugs. When the locating tone was being sent, I heard actual reflections off the back wall where the listening spot is - which is mostly window.
Mr Pass, thanks for the input. I believe you're correct. I'm quite limited, however, in what I can do about it.

When I brought the Abbys home, my wife asked how long they'd be in the living room - not if they'd stay. I also believe her acceptance of them falls off at the inverse square to the distance they are from the wall :D