[sfx] [sfx]:Thumpinator

bass keyboards recording audio

The Thumpinator is a bandwidth optimizer designed for bass guitar. It removes the low frequency signals that are outside the range of notes produced by bass guitars.

Subsonic frequencies cannot be reproduced by standard bass cabinets but they often make amplifiers clip especially when they are set to boost the lower frequencies. The Thumpinator filters the signal content optimising the energy delivered by the amplifier. Low frequency clip is substantially reduced and the sound is tighter especially at high volume levels.

The Thumpinator has servo-balanced input and output. It also accepts instrument and line level signals. In other words it can be connected to balanced and unbalanced devices (also balanced-in/unbalanced-out and vice versa). It can be used between preamplifier and amplifier or between bass and amplifier or anywhere in the effect chain.

If used with unbalanced input and balanced output it can also operate as a DI.



  • Hand made
  • Built using the finest components
  • balanced/unbalaced input and output
  • Power supply: 7-10V, 2.1mm centre negative, regulated. It can be daisy chained.


At [sfx] we keep our devices design constantly under review. For this reason, the specifications are indicative and they may vary without notice.



 Customer comments

from http://www.talkbass.com/reviews/showproduct.php/product/1568/cat/500

Review Date: Sat December 12, 2009
Would you recommend the product?: Yes
Rating: 10
Pros: small, effective, transparent, versatile
Cons: barely a negative, but it needs a 9VDC power supply

   I use a PA-type power amp in my bass rig, and I became concerned about the possibility of high-power low-frequency peaks damaging the speakers (and "wasting" wattage). These low peaks can come from string thump, sub-octave effects, mic stand rumble, etc. Actually there is a large range of these peaks from filter effects that are in the normal BG frequency range, so they require a different solution. But for anything below 30 Hz, who needs it in the audio path at all?

   I posted a thread asking which amps feature a high-pass filter for speaker protection, and a bunch of people answered "they all do, what are you worrying about". So then I asked for any documentation supporting that claim, and they came up with almost nothing--only one amp model they could find had this info in its specs. The Genz Benz guys came in and stated clearly that they do use such a filter in their amps, so I appreciated that knowledge. Sure other amp brands do too, but which specific brands and which specific models? SWR is famous for not using such a filter in many of their amps, so we cannot assume every amp is the same.

   So I decided I wanted a small external filter specifically for this purpose. It had to cut off everything below 30 Hz at a steep slope, and ideally it would be compatible with both instrument-level and line-level signals, and also it would be nice if it could operate as either a balanced or unbalanced device. That way I could use it with any type of preamp, or in line between my bass and any amp.

   TB'er "Silent Fly" has a small effects brand called [sfx] out of the UK. He saw my posts on this subject, and said he might be able to make this item.

   Boy did he! I wasn't sure what kind of results I would get from this relatively unknown maker, but damn he hit a bullseye. We named it the "Thumpinator" as it terminates string thump. It does exactly what I described, and it does not color or harm the signal in any way--totally inaudible. The low B is not audibly impacted, but anything below it is gone. As a bonus, it actually can convert an unbalanced input to a balanced output, making it a perfectly good DI box.

   It is the size of a small stomp box, it has no controls, and it runs on standard Boss-type 9VDC. The jacks are TRS 1/4".

   This product gets my highest recommendation! It may not be something everyone would find useful, but for anyone like me who wants full control over their signal, it's perfect. There is nothing else quite like it on the market.

   Silent Fly also ordered several more circuitboards for this design, so he is able to make this item to order for you. PM him through TB, or email him . I can also say that the entire process of developing this product with him, and his communication on the business end, was a delight. I encourage you to do business with him.

- Bongomania