Ashdown Klystron 500 Head
Ashdown Klystron 500 Head

Klystron 500 Head, Bass Guitar Amp Head from Ashdown in the Klystron series.

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iamqman 03/18/2011

Ashdown Klystron 500 Head : iamqman's user review

« Best Bass tone Period!! »

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I want to say there were less than 100 or 200 of these things made. I believe John Entwistle from The Who collaborated with Ashdown to design this preamp befor he died. My band picked one of these up a few years ago by trading some gear. I wish that Ashdown would bring back a reissue of this pre with the ABM 1000. We had this combo pared with an 8x12 Ampeg cab. The bass tone we got with this preamp was so full and filling in the room, and recording with it was a pleasure. The thing had an FET circuit that gave such a warmth to the tone that GK or Ampeg could never even match.


We had to play around with it a little bit to find the sweet spot. This was our first Ashdown product so the unfamiliarity factor was apparent. I think it took us some trial and error but eventually we found a good tone for the guitar and cab we were using. Since then we have changed things around but I remember most of the dials were set around noonish. The preamp was constructed to stay around the mid point and dial in the EQ with just very little shifting of the knobs. I used more of the Valve drive knob and the Sub harmonic to really tailor the tone. These two features are fantastic! Being able to dial in a little grind to bass while adding sub octave chorus to the tone was amazing. To this day I haven't played a better bass head or preamp that could match up to this tone. John was a tone purist...just look at his ugly bass guitar condor bird he built for himself. He said it looked ugly but had a tone no other guitar could match and this preamp follows that same approach to music. Although this unit was nice to look at.

We didn't get a manual since we got it on the used market but Ashdown does have a manual available on their website if you get the pleasure of finding one of these pre's.


The tone was remarkable! Just pure bliss, which makes listening to the bass a little pleasurable. I usually ran the Valve and Sub around 2:00 and I enjoyed having these two knobs follow each other since they blended so well. The compression we used sparingly since I found that it doesn't allow the bass to bloom as much but gave a little more bottom end. So this knob was just barely engaged.

We used this with a Rickenbacker 4003 and a ABM1000 power amp. We had some trouble with the power amp but luckily we had a spare. We had a solid rock/metal bass tone that fit in with just about any band situation...other than jazz fusion.

Since they only built a hand full of these things not many people are even going to play them. However. Ashdown brought back the Klystron in a head form a few years ago and to which they discontinued that as well. However, you can still find some around on ebay and such. Now I believe the new EVO lll's are the new recreation of the Klystron. It seems to have the exact same features and sound.


There isn't anything to say negatively about this preamp. It was the perfect unit to get blooming, punchy, and responsive bass tone. It was warm and smooth while staying very tight and driving. So many professionals turn to Ashdown for their bass needs and this preamp to me is the best they ever did.

I would recommend trying to find this preamp if you can because it could be a collectors item at some point. If you need something right now then I would look at new EVO lll.