Impedance Matching With Tube Amps

[Ralf Biermann]

Hello All,

I was wondering if a tube amp works better with a full range speaker than with two or three way speaker systems, because a full range speaker doesn't need a filter in front of it. Has anybody tested it?

 

[rock soderstrom]

Hello All,

I was wondering if a tube amp works better with a full range speaker than with two or three way speaker systems, because a full range speaker doesn't need a filter in front of it. Has anybody tested it?

I haven't compared them, but I listen at home with a 2A3 tube amp with fullrange ALR Jordan DIY speaker without crossover. It sounds good, but I don't have a direct comparison to other solutions.



Note the plant in the bucket, it is on winter vacation in this place.

 

[Tubetec]

A single drive unit has plus and minus ,
Firstly it wont ever cover the whole frequency range effectively ,
but it does have the advantage that its a single point source , not two drivers ,mounted offset by a distance , like most 'hifi' speakers ,

In the last number of years for domestic listening I've been using a set Fostex Pm03's with passive biamp and a single Kef 104ab converted with a sub woofer panel ,
The Fostex being a 3 inch mid and 20mm tweeter they approximate a point source very well in the nearfield ,in the mid field, spaced out a bit , even more cohesive ,
I use a Canford amp on the 3inch driver , it has selectable internal HPF which allows me dial in the crossover point with the sub ,

I used Miles Davis on the corner out-takes and Santana as my reference material ,
then set it up by ear , to my liking and that was it ,
No REW measurement suite , nor did I have any kind of measurement mic with credentials.

 

[JohnRoberts]

Solid state audio power amps generally have lower output impedance than vacuum tube amplifiers, so will care less about speaker loading.

Loudspeakers "should" be designed to present a reasonably flat load impedance to the power amplifier. In the real world we all live in loudspeaker design engineers are more highly motivated to deliver flat output signal, than flat load impedance.

When I worked inside a company that manufactured both amplifiers and loudspeakers we experienced first hand issues from loudspeaker designs that cut too many corners.

Long answer short your mileage may vary, avoid broad sweeping generalizations.

JR

 

[Walter66]

A good designed frequency network in combination with impedance friendly drivers is no pushback for a tube amp.

What tube amps often fail to deliver is current, so they may become problems with low impedance sections on the network transfer curve of the speaker.

Transistor amps can have advantages when it comes to low impedance speakers because they can deliver high currents.

When it comes to output power vs. needed energy for a given level of performance (decibel) most modern speakers therefore prefer transistor amps. They can push the current into those mediocre non-loud speakers with modest to horrible efficiency.

And often those speakers have high energy consuming, complex frequency networks, too. The combination of low efficiency network and low efficiency (multi) driver speakers can literally kill the performance of even a muscular tube amp instantly.

Comparing those modern low eff. speaker designs with a good fullrange, the wideband can indeed be better suited to a tube amp.
But no rule without exceptions, one can design a multi driver, high efficiency speaker with a low energy consuming and simple constructed frequency network and it will perform more tube friendly compared to a modern, low impedance wideband speaker.

 

[Rusan]

I have a <1 watt per channel amplifier I built using 12B4 triodes as output tubes, into a pair of speakers with full-range Fostex drivers that a friend designed and built. The focus, clarity and midrange phase coherency are unreal, and it can still achieve higher SPL than I personally like to listen to.