December 30, 2014

PSE-144 crossover boards


HTS-215 is a horn sub kit with dual 15" drivers. 

It features:
  • ultra low distortion
  • 20 Hz extension with authority
  • extreme high output 
  • minimal box vibration due to the dual opposed driver mounting
The kit design allows for simple construction. For simplicity only some of the panels are shown here. The panels are CNC cut and slot together in a way that avoids the need for screwing panels together and mostly eliminates the need for clamping.

December 7, 2014

HE3 - an elegent valve friendly speaker

Here's a dilemma. How do you create a speakerthat meets all these goals:
  • easy for a valve amplifier to drive (benign impedance load and high sensitivity)
  • a slim and elegant design (tall and slender rather than wide and chunky)
  • pleasing tonal balance with full bass and no emphasised regions to get a high sensitivity rating
  • strong bass extension
Based on the questions I'm often asked, it's much harder than people realise. Often people don't realise the implications of each decision. If you want a slender box that isn't very big, with good bass extension, generally it's going to mean it won't achieve high sensitivity.Something has to give. 


HE3 is my answer. First we start with a conventional dome tweeter with fairly high sensitivity and an exceptional midbass driver - Acoustic Elegance TD6M. Here we achieve 93 dB sensitivity which is quite reasonable. Many speakers claiming higher don't actually deliver it. This is a spec that is often inflated excessively. Even individual drivers rated at 99 dB in reality may only have 93 dB of useful sensitivity.

Now the key in this design is that the bass is active, with a side firing 10" woofer. Here we dispense with high sensitivity and use brute force with a built in amp that also features DSP. The added bonus is that we can use EQ in the room.

Prototype coming soon.

Sonus Faber Cremona Auditor active crossover conversion

 The Sonus Faber Cremona Auditor is a fairly well known speaker using good quality drivers in a beautiful box. A client brought in a pair that he was not happy with, requesting an active crossover design. This is a speaker that measures quite well in terms of dispersion but it's not a speaker that handles higher levels very well. At moderately loud levels it sounds strained, most likely due to the use of a first order crossover with a ring radiator tweeter which is not ideally suited for a situation such as this which places heavy demands.

Raw response with the tweeter response raised for clarity: In reality they overlap each other.

No obvious breakup peaks are evident here.

The raw response of the woofer (green) shows a rise in the region from 700 Hz - 2.5k. This is eliminated with EQ (blue) and then a low pass filter is added.

 The same approach is used with the tweeter, first applying EQ and then a high pass filter.

Summed crossover.

This isn't shown here but I use a shelving filter to adjust the treble balance. This allows for a lot of adjustment later without messing up the crossover. 

This is just a quick snapshot and not the entire battery of measurements that were taken and analysed. 

Even a brief listen reveals an obvious improvement in the sound. The speaker is now entirely free of problems with a forward and strained sound.

December 6, 2014

HS215 - a horn sub with dual 15" drivers

Introducing HS-215. This is a custom job for a client and it's designed to sit behind a couch in place of a shelving unit. Designed as a flat pack where panels lock together such that large clamps can be avoided.