Tom Christiansen Audio HPA-10 Review (Headphone Amp)

[gvl]

@tomchr , I'm enjoying your HPA-10 since some time ago. So much clarity, it made me promptly retire the SMSL SP400 I thought was my end game amp, sure it had more power but I didn't really need it. Not to ding the SP400 as it was very good still. I realize the measurements don't really show it but to my ears the HPA-10 is yet cleaner in the mid-high frequencies, perhaps this has something to do with driving real vs. dummy loads. This wasn't a proper blind test, so it's possible some bias creeped in...

Couple of questions:
1. There is a rather loud but short pop in the headphones when it's powered off using the power switch, is this normal/safe?
2. Is the HPA-1 design similar topology but balanced inputs and more power or is there more to it?

 

[tomchr]

The turn-off pop is unfortunately one of the tradeoffs I had to make to drive the cost down on the HPA-10. The pop is perfectly safe and short lived, but some find it annoying.

The HPA-1 is a higher end design. It's balanced all the way to the volume control and unbalanced from there. So I'd argue it's a different architecture than the HPA-10. It's certainly not simply a scaled up version.

In addition to the obvious feature differences (balanced inputs, gain switching, built-in power supply), the HPA-1 also includes some design details that increase the longevity of the amp. In particular the mounting bracket that hold the volume pot and output connector will ensure that the amp will work reliably for a long time to come. The volume pot is of a higher quality as well.

I have about 25 HPA-10 left in stock. They're on sale while supplies last. I'll be moving upmarket as I'm having more fun designing higher end amps than cost-optimized ones.

I'll be attending the Florida Audio Expo this weekend, so if you're around Tampa, FL please swing by. The Expo is held at the Embassy Suites at 555 N Westshore BLVD.

Tom

 

[gvl]

Thanks, the turn off pop doesn’t really bother me as long as it’s not hitting the drivers too hard, which sounds like to be the case. I guess I’ll be putting the HPA-1 on my wishlist, hoping for a next clearing sale event when you move to a yet higher-end market

 

[tomchr]

The pop dissipates a few mW in the headphones. Headphones are typically rated for 100-200 mW.

I have no plans for putting the HPA-1 on sale. In fact, I'll be making more of them as soon as I can get parts.

Tom