ELF and Power tubes.

[Red Brown]

1. What is the DC resistance of your speaker?
That is almost certainly also the impedance of the speaker at 5Hz.

2. Is this an OTL amplifier (no output transformer, just an output capacitor)?
If there is not enough capacitance, the output tubes voltage swing may be "from rail to rail".
At some low frequency, the capacitive reactance is very high impedance, and so the output tubes will not be loaded.

it is a headphone amp, and the phones are 16ohm.

 

[Red Brown]

Are they OTL? Pictures? Schematic? Make and Model?
No normal tube output transformer is rated for full power at 5Hz.
I make tube amps that will pass 5Hz but not at full power.

I dont have a good schematic. It is a tube headphone amp. Ill upload a pic later.

 

[wg_ski]

Ah, tube HEADPHONE amp. Not talking about a lot of power, and doesn’t necessarily need an impedance match to the load. Probably running class A with little chance of damage from mismatch, ultra low or high frequency.

 

[Red Brown]

Ah, tube HEADPHONE amp. Not talking about a lot of power, and doesn’t necessarily need an impedance match to the load. Probably running class A with little chance of damage from mismatch, ultra low or high frequency.

Yes, My SVT is a different story! That thing can cause damage to itself and to speakers.

 

[Technical]

I must admit I did not design nor build them myself, but I've verified 42 watts at 5 hz from my MCINTOSH Mc30s
My 50 watt rated Acrosound Ultralinear 2s also deliver right at 50 watts, at 5 cycles under half a percent.
They wont do full power at 4 hz.
They do it at 5.
Not many can pull that off.
Sure is fun finding out that information though.

I guess it’s time for me to dust off my Acrosound UL-2’s and listen to them!
And my rusty MC30’s (pair of reproduction chassis are sitting in a box awaiting a solution to the rivet issue. I prefer the rust to screws and nuts on a perfect chassis.