A 1958 Blaupunkt New York Stereo radiogram with FM (mono and stations only up to 100 MHz) and 12 speaker drivers (6 each side) and an echo chamber in the back (speaker one end/microphone other) for an artificial echo effect. Its full of Siemens and Telefunken tubes. Works great!ashok said:
At the risk of hijacking this thread here is a better pic of it:
I wonder what you might see off-centre in that one...
OK..back on topic:
I think 12 inch drivers are too small for good bass even with long throw versions. The Peerless XLS drivers are pretty good as far as small drivers go though I guess. I particularly like their innovatove voice coil cooling method - an array of holes through the cone under the dust cap. I suppose that the strange whistling sound on low frequencies (below 20 Hz) at high power levels is air rushing through them, but it is not audible on normal program.
Oh...here is a video of the silly subs doing a bit of a shaky-shaky thing just after I finished them. Notice no CD, no DVD...where does that come from?
I wonder what you might see off-centre in that one...
OK..back on topic:
I think 12 inch drivers are too small for good bass even with long throw versions. The Peerless XLS drivers are pretty good as far as small drivers go though I guess. I particularly like their innovatove voice coil cooling method - an array of holes through the cone under the dust cap. I suppose that the strange whistling sound on low frequencies (below 20 Hz) at high power levels is air rushing through them, but it is not audible on normal program.
Oh...here is a video of the silly subs doing a bit of a shaky-shaky thing just after I finished them. Notice no CD, no DVD...where does that come from?
An externally hosted image should be here but it was not working when we last tested it.
It's gorgeous !
Where did you get this one in this condition?
What about that clock ? That looks great too !
Antique collector ?
Cheers.
Where did you get this one in this condition?
What about that clock ? That looks great too !
Antique collector ?
Cheers.
Radiogram was sourced in Melbourrne. Yes collect deco clocks etc....
I have just read through this entire thread and a few pages back there was some discussion of using two subwoofer drivers to achieve a 6 dB gain which is not entirely correct.
Lets say you have a mono amp and a single bass driver in a box and that gives a certain sound level. Adding a second identical driver (in a second identical enclosure alongside the first one, or doubling the internal volume of the enclosure and installing two drivers in it) and connecting the two drivers in parallel (or series) and powering them with the same mono amplifier will NOT give a 6dB gain because the amplifier's output power is shared by the drivers.
The "mutual coupling effect" for two drivers applies when you double the input power by adding a second amplifier of the same power (or using a single amp of double the power) and is a result of the close mutual proximity of the drivers. If you seperate the drivers (eg. having two sub boxes) by more than about 1 wavelength (which at say 80 Hz is about 4.3 metres), then the gain with two amplifiers (or one double-powered amplifier) - compared to just having the one original amplifier and one of the subs - is just 3 dB as expected by the double power = 3 dB gain rule.
I have a DIY dual 18 inch subwoofer with each driver connected to a respective channel of a stereo power amplifier with input attenuators on each channel. I split a mono input (.1 signal) at line level into the stereo amp. With a constant input tone of say 50 Hz chosen arbitrarily, attenuating one channel to zero reduces measured SPL by exactly 6dB.
I cross my subs over at around 80 Hz because my room is only about 4.3 metres wide and the subs are spaced across the front wall. At frequencies above 80Hz there would be a sudden drop in output as the drivers acoustically decouple.
I have just read through this entire thread and a few pages back there was some discussion of using two subwoofer drivers to achieve a 6 dB gain which is not entirely correct.
Lets say you have a mono amp and a single bass driver in a box and that gives a certain sound level. Adding a second identical driver (in a second identical enclosure alongside the first one, or doubling the internal volume of the enclosure and installing two drivers in it) and connecting the two drivers in parallel (or series) and powering them with the same mono amplifier will NOT give a 6dB gain because the amplifier's output power is shared by the drivers.
The "mutual coupling effect" for two drivers applies when you double the input power by adding a second amplifier of the same power (or using a single amp of double the power) and is a result of the close mutual proximity of the drivers. If you seperate the drivers (eg. having two sub boxes) by more than about 1 wavelength (which at say 80 Hz is about 4.3 metres), then the gain with two amplifiers (or one double-powered amplifier) - compared to just having the one original amplifier and one of the subs - is just 3 dB as expected by the double power = 3 dB gain rule.
I have a DIY dual 18 inch subwoofer with each driver connected to a respective channel of a stereo power amplifier with input attenuators on each channel. I split a mono input (.1 signal) at line level into the stereo amp. With a constant input tone of say 50 Hz chosen arbitrarily, attenuating one channel to zero reduces measured SPL by exactly 6dB.
I cross my subs over at around 80 Hz because my room is only about 4.3 metres wide and the subs are spaced across the front wall. At frequencies above 80Hz there would be a sudden drop in output as the drivers acoustically decouple.
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