Tube Power Amps--Which can drive low impedance loads?

[Steady339]

Is it the power supply that determines if a tube amp can drive low impedance speaker loads well? That is, can modern tube amps with their larger power supplies easily drive low impedance speaker loads? I have read that vintage amps with their smaller power supplies had trouble with low impedance loads.

What are some modern tube amps that can drive low impedance load well?

Also, I have read that in general, tube amps are high-voltage, low-current devices and transistor amps are low-voltage, high-current devices.

Are there any high-current tube power amps?

[jdandy]

Roger.......How low an impedance are you talking about?

The McIntosh MC275 MkVI can handle 4 ohm loads in stereo mode and 2 ohm load in mono mode.






The McIntosh MC2301 can handle 2 ohm loads.

[Steady339]

Dan, my Paradigm S1 speakers (90 dB efficient) are rated at a nominal impedance of 8 ohms, but looking at their impedance curve they drop down to 3 ohms (see attachment).

My system is in a small office room so was thinking more toward a low-power EL-84 based tube monoblock amp like a Manley Mahi (40 watts ultralinear and 20 watts triode).

I phoned Paradigm and they suggested a high-current amp like Anthem. They didn't seem to know if the Manley would be a good match for the S1. Do you think a modern amp like a smaller Manley would be a good match?

Roger

[mulveling]

To deliver an optimal balance of high power and low distortion, tubes need to see a load of a certain impedance. The output transformer taps give you various multipliers, from which you can hit the sweet spot for a wide selection of speakers.

However, if a speaker has significant low-impedance dips at certain frequencies, then it may lend itself better to "high current" solid state amps, which simply deliver more power into lower impedances until they become unstable and/or melt down. On the other hand, a high-impedance speaker will not be able to take advantage of the full power capabilities of a high current SS amp.

Some speakers are just designed to work better with SS, others with tubes, and some are in the middle. Atmasphere calls this the "voltage paradigm" vs. the "power paradigm". If you have a speaker with low-impedance dips and a tube amp, then you're usually (though not always) better off selecting a tap that is lower than the speaker's listed nominal impedance (e.g. use the 2 ohm tap for a speaker at a nominal 4 ohms that dips down to 2 ohms).

[Mikado463]

good explanation 'mul'..........

[drjjpdc]

Steady,

You didn't specify mono amps or not. I have a Jolida 1501 BRC Hybrid Integrated that is great. It's rated at 100 watts RMS but they have smaller hybrid models. Solid state power supply and tube preamp section. Save money with less interconnects. One of the better integrateds I have heard and less than a grand!

[Steady339]

Originally Posted by drjjpdc

Steady,

You didn't specify mono amps or not. I have a Jolida 1501 BRC Hybrid Integrated that is great. It's rated at 100 watts RMS but they have smaller hybrid models. Solid state power supply and tube preamp section. Save money with less interconnects. One of the better integrateds I have heard and less than a grand!

drjjpdc, I already own a Counterpoint NP-100, a very good hybrid amp--although a little thin sounding compared to the even-order rich harmonics of a good tube amp. I was considering a Manley Mahi, as I stated in an earlier post. The Manley Mahi is a tube mono block amp--so yes, I am considering mono block amps. Not interested in integrated amps as separates gives me more options and potential.

Roger

[Steady339]

Originally Posted by mulveling

To deliver an optimal balance of high power and low distortion, tubes need to see a load of a certain impedance. The output transformer taps give you various multipliers, from which you can hit the sweet spot for a wide selection of speakers.

However, if a speaker has significant low-impedance dips at certain frequencies, then it may lend itself better to "high current" solid state amps, which simply deliver more power into lower impedances until they become unstable and/or melt down. On the other hand, a high-impedance speaker will not be able to take advantage of the full power capabilities of a high current SS amp.

Some speakers are just designed to work better with SS, others with tubes, and some are in the middle. Atmasphere calls this the "voltage paradigm" vs. the "power paradigm". If you have a speaker with low-impedance dips and a tube amp, then you're usually (though not always) better off selecting a tap that is lower than the speaker's listed nominal impedance (e.g. use the 2 ohm tap for a speaker at a nominal 4 ohms that dips down to 2 ohms).

Mul, Thanks for your response. One last question, would my Paradigm S1 speakers with the 3 ohm impedance dip likely be a good match for a tube amp on the 4 ohm tap, or would I need an amp with a 2 ohm tap to handle the impedance dip?

Roger

[Victor tubeman]

Audio Research REF 300/600 versions(mkii,mkiii) can handle 1 ohm loads with ease.