My System Went Horizontal in 2023

[knotscott]

Back in early 2020 I revamped my old Dynaco tube amps with the VTA mods from Tubes4Hifi, and wired them in a vertical bi-amp configuration using two stereo amps. The VTA mods and bi-amping took the system to another level, and I was pretty happy. After hearing the Magico S5 MkIIs at Convergent Audio, i started to think the bass didn't have quite the control and slam that it could.

Sometime in March 2023 the system got reconfigured again, but this time into a tube/solid state hybrid horizontal bi-amp setup. I see it as the best of both worlds. Each amp type doing what it does best. It helps that each driver of my 3-way speakers has it's own input, so are fairly conducive to bi-wiring, bi-amping, or tri-amping.

The twin stereo Dyna/VTA 70 tube amps got solid state rectifiers, are sporting new Tung Sol 7581A output tubes in triode, and are now run as single channel mono blocks, which still leaves me with the outstanding separation offered by vertical bi-amping. They're only powering the 5" midbass and tweeter now (which have a natural acoustic rolloff at about 80hz). The tube amps now see an easier to drive 8 ohm load (vs 4 ohm) and lighter woofers...they sounded notably clearer immediately. (a pleasant, but unexpected side effect!)

The solid state amp is a vintage Kenwood KA-3500 integrated amp that only drives the main 8 inch woofers from 80hz down. (It also feeds the active subwoofer with a high level signal). A couple of months after experimenting with this I added an active low pass crossover ~ 80hz, then bypassed the passive low pass crossover to the woofers. Yep, there's more bass control and slam, and it really lets the transmission line shine.

The signal from the preamp gets split between the tube amps and the SS integrated amp. This configuration treats the Lazarus preamplfier as a master volume for all the amps, while the integrated amp has it's own volume control for everything below 80hz. I can vary the output of the woofers and sub separately relative to each other, and relative to the tube amps that feed the midbass/tweeters. In addition, the active crossover has it's own gain settings, so there's lots of flexibility to dial in low frequencies however I want, and not impact the vocals of the midbass driver.

Some new copper inputs for the mids and tweeters, new Furutech OCC cables, and a new phono stage round out 2023 as a successful year of fairly aggressive upgrades for relatively low cost. The system is all coming together nicely just in time to enjoy a wonderful Christmas music season. All in all the changes have resulted in easily audible improvements on multiple levels IMHO. Overall clarity is better, and bass is notably tighter and more dynamic, and provides the ability to fine tune bass output. Cost for used the integrated amp and active crossover were under $100 (way less than new tubes!). I'm extremely happy with this setup, and am glad that I went down this path.





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[Masterlu]

Nicely done, thanks for sharing!

[Charles]

knotscott, I don't know enough about the speakers or your gear to say anything other that your system seems extremely well thought out and the cabinet is beautiful. I have a soft spot for well made wooden cabinets. If your system is competitive with the Magico S5 MKII system, and it sounds like it is, then you must have a very fine sounding system. Your room is beautiful and inviting.

Best

Chalres

[knotscott]

Originally Posted by Charles

knotscott, I don't know enough about the speakers or your gear to say anything other that your system seems extremely well thought out and the cabinet is beautiful. I have a soft spot for well made wooden cabinets. If your system is competitive with the Magico S5 MKII system, and it sounds like it is, then you must have a very fine sounding system. Your room is beautiful and inviting.

Best

Charles

Thanks Charles. Sorry, for the delayed response, but I didn't see your comment earlier.

The system sounds really good to me... better than it ever has, and it's sounded good for a while IMO. The speakers are a transmission line design with Focal kevlar woofers/mid, and a modified Seas aluminum dome with 2nd order passive crossovers between the mids/tweeters that use top notch quality parts (CAT caps, Litz wire inductors, Dale non-inductive resistors, wired with Kimber Kable). I think it'd be a bit of wishful thinking to consider it at a level with the CAT/Magico system, but it's not bad.... more than good enough to meet my needs, and I'm pretty happy with how it sounds. I'd say it sounds "see through".