I'm making a pair of desktop speakers with the following driver/horn complement:
Dayton Audio H6512 6-1/2" x 12" Waveguide 1-3/8"- 18 TPI
JBL 2414H-1 (with non-official replacement diaphragm)
4*TC5FC00-04 1.5" driver
2*SB16PFCR25-8 6" driver
The plan is to have the midrange and tweeter on the horn rotated so that the long side is vertical and to have the bass drivers output through narrow slots above and below the horn in order to reduce the centre to centre distance and front face size.
The project started from the tweeter as I had spare magnets to re-use from replacing a pair of burnt out tweeters (no diaphragm kit available from JBL). I rebuilt these with some Ebay diaphragms. This is probably not an idea choice as the diaphragm is only ~1" diameter and so low frequency output is limited. Multiple entry horns with bandpass midrange often have issues with the mid ranges getting high enough in frequency to meet such a tweeter, as such very small mid-ranges that can be positioned close to the throat have been selected. However other measurments of this horn and a similar driver indicate performance at high frequencies will be good.
Measurments of H6512 with JBL 2414H-1:
This is a 4 ohm driver so this is the 2W SPL:
Distortion at differing drive levels:
Microphone used is ECM8000 so 120dB is reaching saturation point for this mic (yes I wore double hearing protection for these measurements). This speaker will overall be capable of <100dB/1m so this tweeter has great headroom. Here is the lowest voltage distortion measurments as %:
THD at low levels look great, comparable to high end tweeters (distortion peak -45dBr@2.55kHz). Crossover at lower than 2kHz might be OK at home levels and if using DSP (undecided atm if its going to be two or three amp channels per speaker). Response is quite equalisable once the smoothing is applied to it.
Dayton Audio H6512 6-1/2" x 12" Waveguide 1-3/8"- 18 TPI
JBL 2414H-1 (with non-official replacement diaphragm)
4*TC5FC00-04 1.5" driver
2*SB16PFCR25-8 6" driver
The plan is to have the midrange and tweeter on the horn rotated so that the long side is vertical and to have the bass drivers output through narrow slots above and below the horn in order to reduce the centre to centre distance and front face size.
The project started from the tweeter as I had spare magnets to re-use from replacing a pair of burnt out tweeters (no diaphragm kit available from JBL). I rebuilt these with some Ebay diaphragms. This is probably not an idea choice as the diaphragm is only ~1" diameter and so low frequency output is limited. Multiple entry horns with bandpass midrange often have issues with the mid ranges getting high enough in frequency to meet such a tweeter, as such very small mid-ranges that can be positioned close to the throat have been selected. However other measurments of this horn and a similar driver indicate performance at high frequencies will be good.
Measurments of H6512 with JBL 2414H-1:
This is a 4 ohm driver so this is the 2W SPL:
Distortion at differing drive levels:
Microphone used is ECM8000 so 120dB is reaching saturation point for this mic (yes I wore double hearing protection for these measurements). This speaker will overall be capable of <100dB/1m so this tweeter has great headroom. Here is the lowest voltage distortion measurments as %:
THD at low levels look great, comparable to high end tweeters (distortion peak -45dBr@2.55kHz). Crossover at lower than 2kHz might be OK at home levels and if using DSP (undecided atm if its going to be two or three amp channels per speaker). Response is quite equalisable once the smoothing is applied to it.
