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Help me convert old speakers to actives
- Thread starter AlmaAtaKZ
- Start date
- Thread Starter
- #183
Will check
- Thread Starter
- #186
Attempt at interpreting:
- the woofer is about 8dB less sensitive?
- woofer (when two used) can be EQd to add a few dB to the curve in the 30-80Hz range?
- woofer can probably work OK up to 3kHz, although there is a distortion peak at about 1.3kHz. Is it treatable?
- tweeter works better from about 2.2kHz, do not use below 2kHz?
- appropriate crossover would be 2.2k, steep (4th order)?
Would welcome any comments from the more experienced.
- the woofer is about 8dB less sensitive?
- woofer (when two used) can be EQd to add a few dB to the curve in the 30-80Hz range?
- woofer can probably work OK up to 3kHz, although there is a distortion peak at about 1.3kHz. Is it treatable?
- tweeter works better from about 2.2kHz, do not use below 2kHz?
- appropriate crossover would be 2.2k, steep (4th order)?
Would welcome any comments from the more experienced.
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At first glance the tweeter seems to have a problem above 8 kHz with an approx. 12 dB lowpass rolloff: is this on axis measurement?
- the woofer is about 8dB less sensitive?
this is not unusual; attenuating the tweeter can help for lower xover frequency and save from frying the tweeter
- woofer (when two used) can be EQd to add a few dB to the curve in the 30-80Hz range?
EQ can do this; if the woofers can follow or be overdriven can only be estimated by paricular measurement and knowledge of driver parameters
- woofer can probably work OK up to 3kHz, although there is a distortion peak at about 1.3kHz. Is it treatable?
the distortion may be generated by the driver itself (no treat), or the enclosure (maybe some damping/bracing might help), or both, EQ won't help here
- tweeter works better from about 2.2kHz, do not use below 2kHz?
distorsions rise from below 2 kHz significantly
- appropriate crossover would be 2.2k, steep (4th order)?
yes, with appropiate attenuation of the tweeter
Some notes:
Adjustment of y-axis (130 dB SPL ?) may be required, but for an overview it is ok.
The woofer, if measured correctly, is almost a fullrange driver, so not problematic to cross in usual range at 2, kHz +-, but dependend on directivity.
Most irritating is the high frequency loss of the tweeter, and even more in the graph of the whole speaker, maybe due to not quiet on axis measurement?
(or a notsogood design of xover)
- the woofer is about 8dB less sensitive?
this is not unusual; attenuating the tweeter can help for lower xover frequency and save from frying the tweeter
- woofer (when two used) can be EQd to add a few dB to the curve in the 30-80Hz range?
EQ can do this; if the woofers can follow or be overdriven can only be estimated by paricular measurement and knowledge of driver parameters
- woofer can probably work OK up to 3kHz, although there is a distortion peak at about 1.3kHz. Is it treatable?
the distortion may be generated by the driver itself (no treat), or the enclosure (maybe some damping/bracing might help), or both, EQ won't help here
- tweeter works better from about 2.2kHz, do not use below 2kHz?
distorsions rise from below 2 kHz significantly
- appropriate crossover would be 2.2k, steep (4th order)?
yes, with appropiate attenuation of the tweeter
Some notes:
Adjustment of y-axis (130 dB SPL ?) may be required, but for an overview it is ok.
The woofer, if measured correctly, is almost a fullrange driver, so not problematic to cross in usual range at 2, kHz +-, but dependend on directivity.
Most irritating is the high frequency loss of the tweeter, and even more in the graph of the whole speaker, maybe due to not quiet on axis measurement?
(or a notsogood design of xover)
- Thread Starter
- #188
The mic was at tweeter axis abt 2cm away from tweeter. I think this is just a very old (25 y) and low to mid spec tweeter.
- Thread Starter
- #189
I am not sure my gain structure is correct. Need to go through a rew setup tutorial properly.
- Thread Starter
- #190
When I later upgrade the drivers I do plan to brace the box, apply deadening to internal walls, fill it with wadding and possibly double the wall thickness by adding an extra layer of mdf - the latter only if the new calculated volume will allow that.
Thank you for the feedback! Appreciate!
Ok, this could be the reason for unusual, but under these conditions, correct SPL.
To linearize the tweeter you could insert (on top of lowpass) a shelf filter to attenuate up to 8 kHz and above let run free.
- Thread Starter
- #192
What other measurements of the three drivers should I do to inform the future active crossover design?
Do I need to measure the port output?
Current thinking:
Xover: 2.2kHz, LR 4th order
HF: attenuate overall level to match woofers, add shelf to attenuate below 8kHz to flatten response
LF top woofer: boost a few dB overall, add shelf to attenuate above 50 or 60Hz to flatten response
LF bottom woofer: same as top woofer
Is this how it is done?
Do I need to measure the port output?
Current thinking:
Xover: 2.2kHz, LR 4th order
HF: attenuate overall level to match woofers, add shelf to attenuate below 8kHz to flatten response
LF top woofer: boost a few dB overall, add shelf to attenuate above 50 or 60Hz to flatten response
LF bottom woofer: same as top woofer
Is this how it is done?
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- Thread Starter
- #193
Step 1 of the project (conversion to active using existing drivers) is progressing. I am about to order the amps and make a new back panels to mount them on. Then it is filter design, eq and tuning. I also plan to mount an AirPort Express on the back of one speaker so they become 'wireless' and can join my multi room setup.
In parallel, I am also thinking through the future Step 2 - replacing the existing drivers with new ones, hopefully bringing better performance. Some box modifications will be necessary, but will be minimised. E.g. I will add a new MDF front panel - this will cover the port and give me a blank panel to install new drivers. I also plan to remove the existing partition (so the full internal volume is available), and then add new partition(s) as necessary, add bracing and deadening and damping.
For drivers, rightly or wrongly, I am thinking of the following two options:
Option 1
- HF/MF: a coax driver e.g. 5in SB link or similar, but not easy to find options
- LF dual woofers e.g. Dayton 5.5in Epique link these seem to be targeted specifically for small boxes
Option 2
- HF tweeter e.g. SB link or similar (not sure yet how to choose even within the SB available range)
- MF single e.g SB Satory or a Scanspeak Revelator/Illuminator that fits on the panel (width being the limiting dimension)
- LF single side firing woofer at the bottom e.g. 7in Epique. link I can find a shallow enough pair of woofers to fit two in opposing config, but a few drivers I checked would require a box much larger than I have, while the 7in Epique needs a remarkably small box - if I got it right that is.
Would appreciate any pointers in choosing the drivers.
- in general, I do not understand how to select the drivers for the box. What parameters and their values do I look for, say, for tweeters. e.g. if I look at SB Satory, then soft domes, 8 ohm, even then there are 4-5 drivers and I have no idea how to narrow it down further (all parameters seem similar to me)
- same for mids - what parameters and in what order of priority?
- checking if the (bass) driver fits the box volume vise: I take driver parameters, enter here link and if the calculated volume is available in my box, it is a go? and if yes, what other driver parameters need checking? and in what order of priority?
- which of the 2 above options is best theoretically (and assuming in both options the drivers can be selected properly)
- are the drivers shown in the above examples suitable for each of the options? and why?
In parallel, I am also thinking through the future Step 2 - replacing the existing drivers with new ones, hopefully bringing better performance. Some box modifications will be necessary, but will be minimised. E.g. I will add a new MDF front panel - this will cover the port and give me a blank panel to install new drivers. I also plan to remove the existing partition (so the full internal volume is available), and then add new partition(s) as necessary, add bracing and deadening and damping.
For drivers, rightly or wrongly, I am thinking of the following two options:
Option 1
- HF/MF: a coax driver e.g. 5in SB link or similar, but not easy to find options
- LF dual woofers e.g. Dayton 5.5in Epique link these seem to be targeted specifically for small boxes
Option 2
- HF tweeter e.g. SB link or similar (not sure yet how to choose even within the SB available range)
- MF single e.g SB Satory or a Scanspeak Revelator/Illuminator that fits on the panel (width being the limiting dimension)
- LF single side firing woofer at the bottom e.g. 7in Epique. link I can find a shallow enough pair of woofers to fit two in opposing config, but a few drivers I checked would require a box much larger than I have, while the 7in Epique needs a remarkably small box - if I got it right that is.
Would appreciate any pointers in choosing the drivers.
- in general, I do not understand how to select the drivers for the box. What parameters and their values do I look for, say, for tweeters. e.g. if I look at SB Satory, then soft domes, 8 ohm, even then there are 4-5 drivers and I have no idea how to narrow it down further (all parameters seem similar to me)
- same for mids - what parameters and in what order of priority?
- checking if the (bass) driver fits the box volume vise: I take driver parameters, enter here link and if the calculated volume is available in my box, it is a go? and if yes, what other driver parameters need checking? and in what order of priority?
- which of the 2 above options is best theoretically (and assuming in both options the drivers can be selected properly)
- are the drivers shown in the above examples suitable for each of the options? and why?
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- Thread Starter
- #194
Digital optical into the master Hypex, then coax to slave. This feeds the digital signal + control to slave (if using IR remote on master).
Drivers shown for Step 2 project.
Drivers shown for Step 2 project.
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