Kaiju Headphone Amp

[Bartman]

I second the previous posts recommending the DC Kit for the Kaiju if it is being used as a headamp.  For me there was way too much hum using headphones with the stock Kaiju even though I heard no hum through speakers.  When I installed the DC Kit it became quiet as can be - no hum at all.

Question: My Kaiju is currently wired for 2 Ohms.  Believe it or not the Hifiman Susvara (83db) could use little more volume for some recordings.   Would wiring it for 4 or 8 ohms give me more volume?

Thanks Bottlehead for such a great product!

[Doc B.]

It's possible that rewiring will give you more volume from the headphones. But in this case you need to asses whether the issue is a lack of drive from amp into headphone, or not enough signal level from your preamp to the Kaiju. Are you turning your source volume way up but not getting a high enough level, or is the Kaiju going into clipping before getting the headphones loud enough?

[Bartman]

The Kaiju is definitely not clipping.  When I turn the source volume up to near full volume I am not getting quite enough volume.

[Doc B.]

Going to a higher output impedance configuration may help, but ultimately you may need to figure out how to get a higher level signal into the Kaiju.

[Bartman]

I'll try the re-wire.  I may also have a DAC/preamp that has higher output. 
 

thanks!

[Paul Birkeland]

There are a few other methods to get what you want.  The first would be to put a preamp in front of the Kaiju.  This will let you crank your source level up all the way (this will maximize SNR from the source, and can potentially sound a bit better) and give you a bit of extra oomph to drive the input of the Kaiju.

You could remove the 100K trim pots in the Kaiju and install a set of 1:5 input step-up transformers to boost the incoming signal, but you have to be careful about how capable your source might be in terms of driving the transformer primary.  Doc B. and PJ will probably grind their teeth a little when they read this, but it's a possibility.

The other option that comes to mind is to use a higher gain tube in the Kaiju.  I don't think this is a good idea, as the 5670 is a marvelous little tube, and I'm not aware of anything pin compatible that will get the job done.  The amp could, however, be rewired for the 12AT7, which would give you a little extra gain (3 or 4 dB I think).

Still, going to the 8 Ohm wiring configuration is the best first step.  I'd probably consider adding a preamp if that doesn't quite do the job.

-PB

[Bartman]

Switching to the 8 ohm output was a good move! Maybe it's mostly psychological but to me the Kaiju sounds MUCH better.  I gained a few db of volume and more importantly it sounds much more engaging.  I am hearing a huge amount of background detail in recordings (eg. artists moving, chairs squeaking, breathing, audience talking).  To me this is a good thing - helps me cue into the space the recording was made in. 
Dynamics and stage are as good or better than I've heard.

I would say using the Kaiju as an amp for my very inefficient Hifiman headphones is a complete success.  Honestly I did not think it would sound as good as it does.  It will definitely make the trip to the next area Head-fi meet.

Thanks Again Bottlehead!