The Torpedo: The Parafeed Tube

Disclaimer: The amplifier used for this review was bought from a fellow enthusiast. 

So, after writing a long HD650 review that culminated in a Bottlehead Crack DIY fest, what should come next? Another DIY tube amp, of course! Yeah… that wouldn’t have been my choice either, and that might have been my problem. It took me awhile to get excited about this amp. Once I realized what I had, however… So, what is it I do have? Let’s find out.

This is the Torpedo, a DIY tube amp with an output transformer. It differs from the Crack in that way as the Crack is an output transformerless (OTL) amp. In practical terms, that means it should do as well with low impedance headphones as it does those with high impedance. It also differs from the Crack in that there is no point to point wiring. Tom B, of DIYforums and, who helped usher along the creation of the Torpedo, wanted to avoid any high voltage, point to point wiring, for safety (smart man). The whole amp is created on one long PCB board, which I find much easier to work with than point to point.

It was designed by Dsavitsk to be a low cost, safe and easy to build amp based on a parafeed design, and using readily available, inexpensive tubes (the 6J6). I understand what low cost tubes are; I have yet to wrap my head around what a parafeed design is and how it impacts the amp. It isn’t the creators fault, as their website is filled with information. I am just woefully out of my depth when it comes to the science behind the sound. For those interested, here is the Torpedo Amp website to at DIYforums. I don’t think there are complete builds available, but if you are interested and would like to try out building an amplifier, head to for the Torpedo kit.


Sound Impressions
So, I fired up the Dacport LX, broke out the HD650 and gave the Torpedo a listen. My first thought was, “ok, it doesn’t have quite the depth of the Crack, and I found the Crack to be slightly more musical. It has a slightly more liquid sound that gives it the edge.” I kept listening, and while I would still give the Crack that edge, the Torpedo sounded good. Real good. To my memory, the Torpedo sounds similar to the Schiit’s Valhalla. It has that sparkly treble, but this time with more body to the mids and a noticeably wider soundstage. So, basically, the Torpedo has the strengths of the Valhalla, but minus the drawbacks. This was a very nice pairing, but what else is there to say?
Well, I remembered the part about the output transformer and thought it would be time to give something with low impedance a spin. I happened to have a Grado SR80 around, so I thought why not throw that into the mix. The Torpedo drives it well with no hiss. The bass is tight and punchy. The treble didn’t make me cringe, and the midrange was full, and quite forward as is the way with Grado. If you are a fan of the Grado sound (i’m not) this will be a good amp with which to show them off.

With my lowly Superlux HD660, the Torpedo is electric. It is just a wonderful combination. Via the Torpedo, the HD660’s bass is tight and hits hard, the mids and vocals are clear and upfront and the treble is just the right amount of aggressive. The energy of the music was palpable with this combination. It never got old. I know the Superlux isn’t the most popular headphone, but based on this combination, I don’t understand why.

If you want a sound similar to the HD650, but with more a focus on jazz and a slightly more open sound, mix the Torpedo with the HE-300. It is another wonderful pairing. Or perhaps you just want one headphone and amp combo that can do anything? If that is the case, the Torpedo and the Beyerdynamic DT 770 32 ohms version will fit that bill. The Torpedo tightens up the bass fairly well, while giving the DT 770 a nice, clean soundstage. The mids and highs are there in the proper quantities. There isn’t much this pairing can’t do… maybe not hard rock. It is another in the line of headphones that the Torpedo drives wonderfully.

What the Torpedo does is make a good case for amp neutrality. To my ears, it doesn’t really favor any frequency more than the others. It would take on the sound of what was plugged into it. Most of the headphones just sounded correct. Were it not for a slight bit of transformer hum, which was unnoticeable while music was playing, this amp would be quite invisible. I myself often prefer a more colored sound to my amps, but the merits of the neutral approach of the Torpedo are clear.
The only headphone I didn’t love with the Torpedo is the HE-400, and it wasn’t really the amps fault. The bass was good. There was no distortion, and it was still clean sounding. The Torpedo had no problem driving it. The issue is that the Torpedo gives the HE-400 a wider soundstage. You would think that would be a good thing, but with rap, hard rock, techno and all of the genres that the HE-400 really excels with, the energy dissipated with the larger soundstage. Funny how that happens. The HE-400 has better genre bandwidth with the Torpedo, but still far from ideal jack-of-all-trades.


End Words
Although I began this review with very little enthusiasm, I had a complete turnaround. Why? Well, it wasn’t just the Superlux combo, or the HE-300 combo, or the DT 770 combo. It was the fact it rocked with just about every pair of headphones my modest budget could throw at it. I have seen some people posting questions about wanting a good amp for the HD650, but not waiting to confine their collection to high impedance headphones with the Crack. Well, here might be your amp. I will be sad to see this amp go. The Torpedo, for a mere $280, will be the centerpiece in a wonderful mid-fi headphone collection. It is available at and is very highly recommended!

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  • Reply June 22, 2013

    Jeffrey Coleman

    Its nice to see mentions of other DIY amp kits, other then Bottlehead’s variety. I know the Crack might be king, but in my humble opinion, there is room for a queen too. This might be it, especially if you are a Beyerdynamic fan. As I tend to feel this is the person I would suggest this project over the status quo…

    • Reply June 22, 2013


      Yes some DIY are good and Ive built quite a few DIY amp as well

  • Reply June 22, 2013


    Picture of the insides?

  • Reply June 23, 2013

    Albert Broman

    I like my Superlux 661. just sayin’.

    • Reply June 23, 2013

      Dave Ulrich

      Don’t need to convince me!

  • Reply June 25, 2013

    skipgap .

    I’m starting to slobber on myself in anticipation of making these myself…the dog is looking at me

    • Reply June 25, 2013

      Dave Ulrich

      I don’t think you will be disappointed. I is a very nice amp.

  • Reply July 29, 2013


    Hi Mike, I would love to build this amp and was wondering how it paired with the HE-500. Thanks in advance for your opinion.

  • Reply February 21, 2014

    Matthew Wingert

    Hi Dave,
    Good to know that the Torpedo doesn’t pair well with the HE-400s. I am looking for an amp to pair with my HE-400s and was seriously considering the Torpedo until I read this review. I have already built a Millett MAX Hybrid amp with some components from beezar, but I am looking for a little more oomph now.
    What are some of your favorite amps paired with the HE-400s?

  • Reply February 21, 2014


    Almost any ss will do. Almost. The 400 isnt too picky

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