This thread will propably not make sense, since I don't really know what I mean but I'll try to explain anyway. I've heard that one of the reasons that most tube-amps sound very tight and controlled bass-wise is because of the outputtransformer. As I understand it the transformer can dampen the current that comes back from a big heavy woofer-cone when it's on it's way back. I'm not sure if you understand what I mean. I guess we've all heard a way too big woofer connected to a way too small amplifier. It just can keep the cone in place. I was thinking about putting a couple of "bass-rockers" underneath my living-room couch to enhance the bass-experience when I watch movies. Since they have a lot of moving mass I thought it would be a good idea to use a big 100volt line-amplifier wich has a transformer-output. What do you think? (please excuse my poor english)
I think you will find that the opposite is true, the output impedence of a solid state amp is much less than a transformer secondary winding. Dunno where you got your information saying otherwise.🙂
A friend of mine connected a 15" woofer with a very heavy cone to this amp and he said the bass was incredible. Extremely tight and fast.
http://www.monacor.de/de/produktseite_suche.php?artid=3795&spr=DE&typ=full
http://www.monacor.de/de/produktseite_suche.php?artid=3795&spr=DE&typ=full
So what I should look for, for my bass-rockers, is a good solid-state amp with a low outputimpedance or even a class-D-amp?
Ex-actly! This tube dude uses a modified Adcom 555 to drive the Big Bad Woofers. You want current, you want control, you want bandwidth, and that all spells "silicon," not "iron."
Just had a quick look at the specs of the adcom 555. The power-figures and the fact that it can drive 4ohm loads when bridged is very impressive, but is a damping factor of 130 really that good? I have basically no knowledge about this but I thought somewhere over 500 would be good when driving big woofers.
Remember, damping factor is the ratio between a standard 8 ohm load and the driving (source) impedance. A DF of 130 is then equivalent to a source impedance from the amp of 8/130, or 0.06 ohm.
But as far as the speaker is concerned, the source impedance includes ALL sources of driving impedance, the amplifier plus the connecting cables plus any contact resistances. If the cable and connectors have a total loop resistance (signal and return) of 0.2 ohm (which is pretty darned good, very short, thick cables), the amp's source impedance is swamped out at any damping factor over 100. For more realistic cable resistances, it's even less of a factor.
But as far as the speaker is concerned, the source impedance includes ALL sources of driving impedance, the amplifier plus the connecting cables plus any contact resistances. If the cable and connectors have a total loop resistance (signal and return) of 0.2 ohm (which is pretty darned good, very short, thick cables), the amp's source impedance is swamped out at any damping factor over 100. For more realistic cable resistances, it's even less of a factor.
Cool... You have explained a lot to me. Thank you very much. Maybe I should try and get my hands on an Adcom 555. 🙂
Really, any decent solid state amp will do, as long as it's got good solid power supplies, lots of watts, and rugged output stages. If you've got the bucks (loonies, I guess!) or can find one used, my Choice One would be Bryston. Marantz made some very nice monoblocks a few years back (can't remember the model, but they were like 400 watts). B&K, Parasound, all nice units. And don't forget Adcom's later offerings; I'd love to have some 585 monoblocks.
In just a few days I will start my new job at monacor, so I would be stupid not to use something from them (soon "us"). I was thinking about something like this: http://www.monacor.de/de/produktseite_suche.php?artid=4002&spr=DE&typ=full
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