Managed to borrow one exactly like the red one pictured in maa2003's post. Not having any absolute reference to test against I lined up 6 rackets of different tensions according to their tones by ear from lowest to highest and then measured with the tension meter. The readings of the device agreed with the ordering by tones. Pairs of rackets that were closer in tones than other rackets also had a closer readings off the device. As for calibration, two of the rackets were recently strung at 23lbs (same model racket, same string) for these the meter showed 21 and 22 lbs - different but also the sounds from the strings were different. Anyway after paying attention to the different tensions on hand i played with the different rackets and really felt that the difference in shots. Anything that measured under 20lbs on the meter was too below par to continue with. I never really payed much attention to tension before, just took it as a given. When playing I just rotated my rackets to even out the wear and only restrung when the strings broke. After this I felt confident enough to cut the racket with the lowest tension and sent it for restringing. So I am quite pleased with the device and think it is worthwhile to have in my kit - at least to gauge tensions when there is no reference racket to compare an new/unknown racket with and to decide when to restring.
How much did it cost you ? I would probably be interested in buying one off you if you can get another one. Maybe through eBay or something ?
Hello Forum Members, Unless you play Tennis as well as Badminton you may not be aware of the various testers which BEERS Technic Gmbh have manufactured in the past. I purchased an ERT1000 tester many years ago from a UK supplier. This tester measures the resonance frequency of the stringbed regardless of the racquet head size or racquet shape. These testers were originally developed to measure the resonance frequency of Squash & Tennis racquet stringbed. My unit was specially modified to read the dynamic tension (DT) of badminton racquets. Only a handful of these units were ever manufactured i.e. they are extremelly rare. I have been informed by BEERS Technic GmbH that they intend to launch a new product that will measure the dynamic tension of badminton racquets in due course. No launch dates for this product were given. I understand that some people on this forum have used a modified version of the Stringmeter which is calibrated for use with badminton racquets. If your reference stringing tension was set to 23lbs on a constant-pull stringing machine and your readout on the new stringmeter was 21-22lbs this would be a good accessory to purchase so you can see when your tension has dropped to am unacceptable level in your racquet. The manufacturers of the ERT1000 recommeded that racquet should be restrung when the tension has dropped by 10-15 %. Please remember the biggest tension loss occurs when you first play with a racquet after it has been restrumg. Take a reading after you first play with a newly restrung racquet and use this as your reference.
I've often wondered whether these machines that "listen" to the sound that a string makes are affected by the string gauge (thickness)?
Yes, the frequency you obtain is different depending on the string gauge, although not huge. The tension meter iPhone app even has a string gauge parameter to take account of it. I'm not sure that app is the most reliable for badminton though, it was made for tennis and quickly adapted for badminton.
string gauge has huge effect on the tone. take a zm62 and a bg65, both newly strung at the same tension and compare them.
Different gauges will have different weights and that will affect the frequency inversely. Thicker string = heavier = lower frequency. Thinner string = lighter = higher frequency. Think of a guitar, the bass stings are the thick ones. The parameters that affect the frequency are: the weight of the string, the length of the string (string bed area) and the tension. Everything else will only affect the envelope of the tone generated. PS jan.v and jshrmohanty - my unit was a loaner so dont know the cost or original supplier ("a shop in China"). But considering its simple construction (plastic dial and a spring) i guess can not be too expensive - say HKD200 with packaging which is about what those online sites above mentioned. I have asked at a few shops here in HK but no luck so far - will update if and when i find a supplier. I would rate its accuracy to be around 5% which is ok for my casual use but maybe not that great for absolute measurements. The digital frequency meter should be around 1% accuracy but probably at 10x the price - if that pans out then they might only be attractive for stringers and clubs. For now using ears + sounds from reference rackets is what i will rely on. (sort of back where i started but with more confidence now)
johnv: with the loaner, did you have chance to try it on rackets with same tension but different thickness string? wonder whether this low price meter is immuned to the string gauge. I doubt it, since it should be relying upon how hard it takes to bend the spring inside it, and this hardness is affected by the string's thickness.
dunmaster: Good Q, my 6 testing rackets had either BG68Ti or BG65 string but not with same tensions to start with - so cant answer that directly. The BG65 strings were lower tension (by sound) but couldn't tell if it was due to the material. My feeling is that the thickness of the different strings probably does not significantly affect the sideways displacement compared to the tension. The elasticity of strings would be significant, two strings with same tension but different elasticity would give different readings from this type of displacement measurement. How different is the elasticity of strings ? maybe that is related to one of yy's string parameters (repulsion?).
