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RE: 845 tube amps

Yah what he says is right. You gotta have the "right" speaker to give you that certain sound you're looking for with ANY tube amp, and more so for low- or no-feedback designs, and ESPECIALLY for low or low-ish power SE tube amps.

There's an Ohms Law interaction between the amp's output transformer secondary impedance and the speaker's impedance that gives some boost here and there to the overall response of your amp / speaker combination. With some amps this variance in frequency response will be a half dB here and there, with other amps it may be as much as 3 dB. Depends on the amp and on the speaker.

Typically, tube amp output stages have much higher source impedance than solid-state amps, again more so for low- or no-feedback amps. Typically this impacts bass response and bass 'quality.' This can have a positive or negative effect on sound quality, again this depends on the speaker. (And to some degree on your listening preferences and sonic taste.)

So you can't really make a blanket statement that a certain amp sounds great- you have to say that on some speakers this particular amp can sound really great.

For example, on my Quad ESL-57's the Mr. Liang 845 SET did not sound very good- highs were rolled off and bass was 'flabby.' Midrange was nothing special. But on a pair of ~96 dB efficient Red Rose Music Classic Ribbon speakers (3-way, vented) the Liang amp sounded extremely musical. Ditto on a pair of small 2-way monitors with SEAS excel drivers (although the 845 was not able to play as loud as I might have liked these little speakers to play on certain music.)

I would expect the SET type amps to sound really nice on certain 2- and 3-way box speakers, especially vented designs that offered high-ish efficiency and moderate current demands, and also on some horn-based speakers. Open baffle woofers, sealed-box designs, electrostats and Magneplanars - not so much.

You can't tell from specs or curves that a given speaker will sound good on a low- or moderate powered SET amp, but you can look at the impedance curves and the efficiency rating of a speaker and identify good candidates for trying out with SET amps. If the impedance doesn't dip too low, if it doesn't have a combination of low-ish impedance and high phase angle, and has at least 94 dB efficiency, I think it would be safe to say that such a speaker would be worth auditioning on a SET amp. Unfortunately, this info isn't always easy to come by, and taking a given speaker / amp combo for a "test drive" isn't usually possible unless you have a dealer that will help you out in this regard.

It is possible to find a great speaker / amp combo, but it is not all that easy.

Science doesn't care what you believe.


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  • RE: 845 tube amps - triamp 05:07:16 07/26/16 (0)

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