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 see an easier to drive 8 ohm load (vs 4 ohm) and lighter woofers...they sounded notably clearer immediately. (a pleasant 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 setup, I added an active low pass crossover ~ 80hz, then followed up by bypassing the passive low pass crossover to the woofers a few weeks later. Yep, there's more bass control, more detail 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 Hagerman 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.
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 see an easier to drive 8 ohm load (vs 4 ohm) and lighter woofers...they sounded notably clearer immediately. (a pleasant 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 setup, I added an active low pass crossover ~ 80hz, then followed up by bypassing the passive low pass crossover to the woofers a few weeks later. Yep, there's more bass control, more detail 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 Hagerman 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.
Horizontal is when you're using two different amps, one for top and one for bottom. Vertical is more conducive to identical amps, one on each side....technically, mono blocks are inherently vertical, so I suppose mine's a hybrid bi-amp setup because it uses both. As with anything, there are pros and cons with each.
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Thanks for the tip Chris. That would be a costly, hard to find failure. Since installing the Kenwood, a bigger, newer Sherwood with a remote has landed in my lap, as has an older Phase Linear DRS250, so I've been contemplating putting either of those two amps into service anyway. (the remote has a lot of appeal to this lazy old man! 😊)
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