[necrozen]

Hello. Please excuse my ignorance as I am new to the hobby. I recently bought a pair of Focal Clear Headphones and a Jotunheim amp/dac to push them. While I love the sound, I am interested what a tube amp or tube hybrid amp would sound like with them. However I keep reading that certain tube amps should not be paired with them.

Here's what I am looking for: A Tube or Tube hybrid amp that will warm up the experience and enhance the bass. I would like for it to have a balanced 4 pin XLR headphone output. It doesn't need to have a dac, as I will just use my Jotunheim as the dac with preouts. My budget is $2000 to $2500 but more would be hard at the moment. As far as the tubes it uses, I'd just like it to accept something with a good variety for me to experiment with,

I've spent a lot of time looking for an answer and I can't seem to find good info. Thanks in advance! I really appreciate it.

 

[tomb]

It's a bit difficult to respond to you directly and stay within the Head-Fi rules. Let's just say that ECP Audio (someone I represent as a MOT) has done the most work in this regard.

The problem is that tubes prefer to drive higher impedance loads, which is totally inappropriate for the Focal headphones. Focals are engineered very much like speakers. Some say that you can even see the driver shifting back and forth (excursions) simply from the air motion produced by swinging the headphone around. That means the Focals have little to no inherent damping. So, the damping factor that results from the ratio of the Focal's impedance and the amplifier's impedance, needs to be high. Since the Focals are low impedance, this can be difficult - if not impossible - to obtain with a tube amp.

OTL (Output Transformer-Less) tube amps are practically out of the question. OTL tube amps, with coupling capacitors, feed the headphone load directly from the tube. As a result, the output impedance of an OTL tube amp is quite high. It's impossible to get a good damping factor with a Focal.

A tube hybrid is a better choice, but it's difficult for a tube hybrid to reproduce all the best qualities of tubes. Yes, you get the flavor of tubes with the tube as the signal stage, but the solid-state buffer will tend to over-ride the effects, especially if it has any sort of feedback.

An output-transformer equipped tube amplifier is better, perhaps even a tube hybrid with zero feedback and transformer output. (Full disclosure: I sell such a device.) Even then, while output transformers can perfectly compensate for the impedance mismatch, there's something called the DC resistance of the transformer that reduces the damping factor even if the impedance is properly matched. Again - IMHO, ECP Audio has done more research in this regard than anyone in the industry, with custom, very-low-DC-resistance Lundahl output transformers. Ultimately, a DC-connected solid-state design may be the optimum choice for Focals, but if you want tubes, what I've described may be one of your best choices.

 

[nishan99]

I don't have any experience with these but they what I found great when I did my research for a tube amp.
Woo audio wa22(in-stock) or Glenn's EL3N tube amp(you need to wait 4 months) < both are transformer-coupled.

You also may want to look at http://ultrasonicstudios.org/ they make "true hybrid" amps and the building time is 1-2 months long but they are new builders and not as reputable as the first two.

 

[buke9]

While I do respect what @tomb has to say on this as he has much more knowledge about these things than I but I have heard the Utopias and the Clears from my Amps and Sounds Kenzie amp (transformer coupled) and thought they sounded fantastic and didn’t hear anything strange at all unlike some low impedance cans on a Bottlehead Crack that was a big bass bloaty mess and not sure if he was worried about damage to the drivers or a sound problem.