ToTo Man
the band not the dog
While clearing out a cupboard I stumbled upon a couple of Goodmans tweeters I completely forgot I had! One is a blue-label DT3, the other just has a narrow white paper sticker on the back with a hand-written serial number beginning with 9xxxxxxxx. From the front it looks just like a DT3 or DT4.
I took the opportunity to measure them on the weekend. The measurements were made in free-space (tweeters plonked on top of a piece of acoustic foam on the floor and pointing straight up towards the ceiling), the mic was positioned 1m above and with a horizontal offset of about 0.4m, because I have found that some tweeters (e.g. Audax TW025A0) exhibit peculiar responses when measured perfectly on-axis if they aren't mounted on a baffle.
Tweeter 9xxxxx clearly exhibits the same response anomaly found in two of the three pairs of Achromats measured in post #1. So too does the DT3, but to a much lesser extent. This weekend I'll attempt to dismantle the 9xxxxx unit and see if it reveals anything.
During my clear out I also discovered a pair of Philips AD 0160 / T8 tweeters, which Goodmans used in several of their models, including entry level offerings such as the Minister, Havant, etc, as well as their better respected ones, such as the Double Maxim, which is a cracking little speaker IMO. I'm a bit confused about the chronology, as I have seen the aforementioned models fitted with both the Philips AD 0160 and Goodmans own dome tweeter (DT2/DT3/DT4) so I'm not sure if they started off with the Philips then moved to their own tweeter, or if they were using both simultaneously to keep up with demand. Do you know about this, Adam (@Beobloke) ?
Troels Gravesen has some interesting comments about the AD 0160. The sample he measured exhibits quite an uneven and upward-tilting response, which is interesting because the pair I measured are surprisingly flat and don't tilt upwards until they get to beyond 10kHz, and even then it's only a 2dB-3dB lift. Some of this difference above 10kHz is probably explained by my measuring off-axis, but as for the response below 10kHz I can only assume that's being caused by baffle diffraction. I'd speculate the best way to mount this tweeter is from the rear (ooh, err, Missus!), so that the baffle is flush with the dome with no gapping).
I took the opportunity to measure them on the weekend. The measurements were made in free-space (tweeters plonked on top of a piece of acoustic foam on the floor and pointing straight up towards the ceiling), the mic was positioned 1m above and with a horizontal offset of about 0.4m, because I have found that some tweeters (e.g. Audax TW025A0) exhibit peculiar responses when measured perfectly on-axis if they aren't mounted on a baffle.
Tweeter 9xxxxx clearly exhibits the same response anomaly found in two of the three pairs of Achromats measured in post #1. So too does the DT3, but to a much lesser extent. This weekend I'll attempt to dismantle the 9xxxxx unit and see if it reveals anything.
During my clear out I also discovered a pair of Philips AD 0160 / T8 tweeters, which Goodmans used in several of their models, including entry level offerings such as the Minister, Havant, etc, as well as their better respected ones, such as the Double Maxim, which is a cracking little speaker IMO. I'm a bit confused about the chronology, as I have seen the aforementioned models fitted with both the Philips AD 0160 and Goodmans own dome tweeter (DT2/DT3/DT4) so I'm not sure if they started off with the Philips then moved to their own tweeter, or if they were using both simultaneously to keep up with demand. Do you know about this, Adam (@Beobloke) ?
Troels Gravesen has some interesting comments about the AD 0160. The sample he measured exhibits quite an uneven and upward-tilting response, which is interesting because the pair I measured are surprisingly flat and don't tilt upwards until they get to beyond 10kHz, and even then it's only a 2dB-3dB lift. Some of this difference above 10kHz is probably explained by my measuring off-axis, but as for the response below 10kHz I can only assume that's being caused by baffle diffraction. I'd speculate the best way to mount this tweeter is from the rear (ooh, err, Missus!), so that the baffle is flush with the dome with no gapping).
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