No announcement yet.

The Strads performance tests.

  • Filter
  • Time
  • Show
Clear All
new posts

  • The Strads performance tests.

    As many here will know, over the past few weeks I have been working on a "Poor Mans Strad "

    Build Thread : Strads

    Over this last weekend I played host to some of our local ( New Zealand) DIY Forum members, some of whom post on these forums as well.

    I was looking for feed back from others on these points:

    1. Clarity & Detail
    2. Sound-stage
    3. Frequency range
    4. Listening Fatigue (if any)
    5. Balance between highs, mids and lows

    I can report that the Strads never let me down. One of my big concerns had been the Titanium tweeter which if left unfiltered could be harsh and a little shrill at times. This is due primarily to its high SPL and a rising SPL response from 14 - 20000 Khz for which I added a contour filter to reduce to 92 dB before the L-pad to reduce over all balance back to 89 dB. It worked out well and I would describe the overall output from the tweeter as being akin to a crisp and airy silk dome tweeter. It not longer exhibits the somewhat metallic crispness associated with metal domes. I was duly pleased as the thing I hate above all others in speakers is really crappy top end.

    Happily the Strads never disappointed. The amp of choice for this weekends event was the venerable Plinius 8150. Although getting a little long in the tooth this amp gives nothing away to its younger siblings. Once it was fully up to operational temp it had the Strads singing. The amps ability to control the overall sound was excellent, with the Strads able to easily match the pace and intricacies of the amp. Detail was excellent and the top end was much better than I had anticipated, the reworking of the crossover and filters worked nicely. I can now go ahead and install a better line of caps in the crossover and change the range slightly as I still feel they are crossed a tiny bit too low in the mid/HF portion. My feeling is that the tweeter still handles a little too much of the upper midrange and the changes would improve on the overall mid range performance.

    Initially when we started our session the comment ( to which I agree ) was that they sounded a little laid back in the midrange. This may in part be from the crossover point being a smidge too low in the mid/HF point, but as time progressed I think this was mostly caused by the amp needing a good half hour to properly warm to its task. From that point the mids never seemed out of place, nor overly bright.

    The use of the Kevlar 6.5 for the mid has turned out to be the smartest change I made to the original design I had seen on Troels website. This speaker best matched the smaller 5.5 inch he had used, and it has really excellent midrange characteristics. Drums are very natural and accurate as are voices. having used this driver in a two way build I already had a pretty good idea of how it would sound in a 3 way. It has a frequency range 35 Hz - 8000 kHz and is an excellent performer in any build I have used it in to date.

    The coated paper 8 inch dome Woofer has been around for a while now and has always been a good performer, although used improperly and without impedance EQ in the crossover can sound a little muddy. But in a well implemented design it is a very adept performer. I had always felt these drivers were capable of 20 Hz or better as I had seen them used in a car audio sub woofer setup so I had some idea of what they were capable of.
    After Saturdays session I got all inspired to do some measurements on Sunday.
    Using TrueRTA and its spectrum analyzer I played various tracks from favorite albums. I wanted to see just what the frequency responses were from the drivers when used in room. I was looking for two things, sustained low Hz output that was audible and clearly defined as to the instrument used to create it. Most tracks ranged between 30 and 50 Hz as their natural bass response at the lower end.

    The final test :

    The track is The Longships from Enya's Watermark Album
    There are periods of sustained notes and percussion between 20 and 24 Hz with shorter bursts down to 17 Hz and a small portion in the
    in the 10 to 20 Hz range. I would attribute anything below the 20 Hz point to be most likely from room gain ( wooden floor ) or the mic exceeding its limits in the lower registers.
    However I think a nominal range of 25 Hz to 20000 Khz would be acceptable for now and with further testing ( with a better mic ) will show even better results.

    The Strads present a light load on the amp and tentatively look to be in the 90 to 91 dB area, so even a modest amp will run them without too much effort.

    I could of course leave things very much as they are and consider it job done and just sit back and enjoy, but hey I'm a diyer .. there must be something better I can build

    Click image for larger version

Name:	DSCF7631.JPG
Views:	1
Size:	458.8 KB
ID:	1186915

    "Gotta Love Dat Sound..."

    Currently Building ..PMS