Tube amps - what 3 things…

Hello all,

I am close to purchasing a tube amp moving away from SS. So far I have listened to a pure sound, PL, and allnic. 

Question for all you experienced owners - if you could do it all over again, what 3 things/features would you look for in an amplifier and what 3 things/features would you not invest in again?




Tubes can be intimidating to start with all the different design approaches and care that is required for speaker matching. Once you start it can be addictive.

Push/Pull (I don't like really hot amps)

Don't spend too much on a tube amp. Some chinese companies (not all) are making excellent tube amps with warranty/ repair centers in USA

Include the cost of the better NOS tubes you will want to roll in

Better electronic components beats fancy features

For example: does any manufacturer use an inductor filtered power supply instead of the much cheaper (and lighter) capacitance filtered power supply? None that I know of.

@xenolith As far as I’m aware, chokes are always used in tandem with capacitors. If you know of a topology that uses only inductors, I’d love to learn about it (Google failed to find any such thing). We’ve been using chokes (inductors) in our power supplies for decades and we are by no means the only one- the use of chokes seems to be pretty common IME.

FWIW, if the amplifier is class A and also ultralinear, you won’t need any adjustment since the correct bias can be automatically obtained using a cathode resistor. Regardless of the transconductance of the tube, if the cathode resistor is correct, the tube will always operate in the A region.

Of course, if you want to manually bias the circuit and run a bias supply (and no cathode resistor) you can, but the tube will be set at the right/same current anyway. One thing that will happen though is that as the tube ages and the transconductance drops off, if you always set to the same current the tube will be over-biased in time.


Ralph, stated another way, if the grid voltage remains constant as the transconductance changes, the current in a bipolar [CT] transformer will be unequal.

Seems like a greater evil... unless one is OTL 😉

The following might seem to be have a air of Negative as reply.

Note I have had a Tube Pre Amp > Power Amp in use since the 90's.

Tube Amp's command a slight alteration to the disciplines of use that can be used with a SS Amp'.

There is a concern for a occurrence where a fire could be the result.

A Drastic Statement it is, but anybody with a Long-Term experience around individuals with a Tube History, will pick up on the need to heed the above and express a 'Vigilance' when using a circuitry that has Tubes.

In a nutshell, when using Tubes it is best to know any early warnings something is amiss with a Tubes Function, it is most reassuring to be able to see the Tube as a operating component with the Power On.

'Vigilance' means being present and observant, aware of developments that suggests a Speedy Power Off Interception is for the best.

I have disciplined myself to be in full time attendance in the Listening Room , with only very short periods of absences during periods that the Tubes are Powered On.

If an individual like to have extended periods without a observation of the equipment in use, the use of Tubes might not be ideal for such practices.

All who I know with Tube Devices are very similar disciplined to myself, which has resulted in not personally knowing anybody who has had a fire in their set up system. I even know one individual who seen an Element start to glow more red than orange and did not suffer any serious outcome as a result of the immediate Power Off that was actioned. 

The same is not said for those I know that extend their use of Tubes to the place where they work with Tube Devices on the Workbench, I know of smoking circuits occurring. 

I do not ever see myself without a Tube Device in use, but recent years have certainly introduced myself to SS Amplification that in my assessment could be used in place of my Tube Equipment. I have already pretty much decided a retirement system to be created, may have a Second Power Amp and a few devices that are SS, as I don't have to be so attentive to these when in use.