I was surprised to find that my Scandinavian Audio Lab 08C08 drivers don't seem to like a very good solid state amplifier. I first tried them some time back in a biamped, open baffle setup driven (directly) by a vintage EL 84 amp, and they were quite nice. In the interim I moved on to try other speakers - vintage Tannoys. I eventually built my M2 clone. That amplifier is wonderful with Tannoys and a leap forward in general from anything I'd had to that point. I recently switched the SALs back in and... I was puzzled and disappointed. Rhiannon Giddens voice became really nasty on one album I was familiar with, for example. As a sanity check, I listened to the same song on some modest two ways in a second system, and there were absolutely no issues. I switched back in my old tube amps and the results, while less holographic than with the M2, were a lot more listenable.
I came across Nelson Pass's article on amp matching and learned that this is old hat - it's common to use tube amps with full range drivers due to synergies that I don't entirely understand.
Just wondering what sort of luck have people had with transistor amps and full range drivers.
I came across Nelson Pass's article on amp matching and learned that this is old hat - it's common to use tube amps with full range drivers due to synergies that I don't entirely understand.
Just wondering what sort of luck have people had with transistor amps and full range drivers.
This synergy has always interested me. Apart from tubes, I have found some but not all class-d amps to mate well with full-range drivers. Also, they use so little power they can be kept on 24-7 without having to worry about tube wear and tear or power draw, it's cold to the touch when not playing.
I have full-range Fostex FE166 (6") drivers in small ported boxes. They sound good with some tubes like 6L6 and 300b, but also sound good with low-wattage class-d amps like the legendary T-Amp Tripath TA2024 which seemed to be the first class-d that made a mark on high-end audio when it was first reviewed by 6moons. The Texas Instruments TPA3110 is also very good cleaner a bit clearer and less tuby than the Tripath. The Fleawatt site makes custom one-off amps and is worth a look for ideas. An improvement over the TPA3110 in my opinion is the Texas Instruments TPA3255 with less background hiss (I use it nearfield so I am sensitive to this) and more clarity. A ready-to-go amp is only ~$70 if you want to experiment before doing something DIY. The cost of all these low-wattage options is so low there is no reason not to try. I tried one Hypex board but didn't like it, however it may have sounded better had I boxed it up in a case. There was some noise from unshielded jumpers.
With the TPA3110 I added a resistor between 1 and 4ohms in series with the speaker this improves the base much like a tube amp by using the speaker's impedance curve. If you overdo it the base gets too out of balance. Tube amps have output resistance because the output transformers' secondaries have a few ohms of resistance. I plan to at some point do more tests with the TPA3255 adding resistance. Decware has a device called Gizmo which is costly and goes also in series with the speaker which I think is worth investigating, but given the cost, I think if I ever get to it I would just DIY it.
I have full-range Fostex FE166 (6") drivers in small ported boxes. They sound good with some tubes like 6L6 and 300b, but also sound good with low-wattage class-d amps like the legendary T-Amp Tripath TA2024 which seemed to be the first class-d that made a mark on high-end audio when it was first reviewed by 6moons. The Texas Instruments TPA3110 is also very good cleaner a bit clearer and less tuby than the Tripath. The Fleawatt site makes custom one-off amps and is worth a look for ideas. An improvement over the TPA3110 in my opinion is the Texas Instruments TPA3255 with less background hiss (I use it nearfield so I am sensitive to this) and more clarity. A ready-to-go amp is only ~$70 if you want to experiment before doing something DIY. The cost of all these low-wattage options is so low there is no reason not to try. I tried one Hypex board but didn't like it, however it may have sounded better had I boxed it up in a case. There was some noise from unshielded jumpers.
With the TPA3110 I added a resistor between 1 and 4ohms in series with the speaker this improves the base much like a tube amp by using the speaker's impedance curve. If you overdo it the base gets too out of balance. Tube amps have output resistance because the output transformers' secondaries have a few ohms of resistance. I plan to at some point do more tests with the TPA3255 adding resistance. Decware has a device called Gizmo which is costly and goes also in series with the speaker which I think is worth investigating, but given the cost, I think if I ever get to it I would just DIY it.
The damping factor is the ratio of the source impedance (~8ohm speaker with frequency swings) to the amplifier output impedance. So adding a few ohms in series with the speaker changes this radically. Try it with your existing amp. Try between 1 to 8 ohms (make sure it's a power resistor of a few watts so you don't smoke it) use whatever you have lying around and some jumpers. Just be careful not to short your amp (hopefully it has protection). I think the class-d amps named above sound good even without dropping the damping, but it does help them grab the speakers in the base region like tube amps do. It's not a magic wand that makes an ss amp sound like a tube amp, but it does go some way in moving it in that direction.
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A filter circuit of some sort came with the SALs that I bought from a community member - it may have been made by one of the folks testing the driver originally. It's a resistor, inductor and capacitor in parallel. I assumed it was meant to be in series with the driver. I did some frequency sweeps to see what difference the circuit made and then put it aside since I didn't like the results in the test. (The filtered results are green in the image.) I did eventually do some listening tests with the M2 and the circuit did reduce the shout (and the high frequencies) but not that much. The tube amp seems to be the best option so far.
