Vovo, can you give some insight into what you're final external dimensions and specifics were? 🙂
Such as whether you went closer to Ralph's design or the old design Rabbitz posted (old one of Ralph's I believe) or a combo of both.
Such as whether you went closer to Ralph's design or the old design Rabbitz posted (old one of Ralph's I believe) or a combo of both.
Front - 206 x 801
Sides - 270 x 900 (the rear was designed to sit 5mm Rebated)
Edit: I went pretty close to the design Ralph sent with the speakers.
If you want I can post up the panel sizes I used, but this would only help you if you are getting them professionally cut as my design requires tolerances of less than 0.5mm.
I did it this way, so I could veneer right up to rear but still have a removable rear section which can be seen in the photo.
Sides - 270 x 900 (the rear was designed to sit 5mm Rebated)
Edit: I went pretty close to the design Ralph sent with the speakers.
If you want I can post up the panel sizes I used, but this would only help you if you are getting them professionally cut as my design requires tolerances of less than 0.5mm.
I did it this way, so I could veneer right up to rear but still have a removable rear section which can be seen in the photo.
Thanks for the measurements, any other info would be much appreciated!
Haha I know I mentioned it already but your execution makes me feel bad a) for not getting this finished yet and b) for not being able to build them to such a standard.
However, I'm learning and having fun doing so.
Thanks,
Matt. 🙂
Haha I know I mentioned it already but your execution makes me feel bad a) for not getting this finished yet and b) for not being able to build them to such a standard.
However, I'm learning and having fun doing so.
Thanks,
Matt. 🙂
well theoretically looking good is of no real consequence at all as they are audio devices they need to sound good everything else is merely a bonus.
Though in hindsight, it is by no means cheap to build your own speakers, considering the amount I ended up spending, I feel I probably should have spent more on the actual drivers.
You could definitely save some money by gluing all panels together and paint it instead of veneer. This would speed up the process from procuring to listening exponentially.
I will try to remember to scan the drawing of detailed dimensions when I get back to work, If I forget remind me.
Though in hindsight, it is by no means cheap to build your own speakers, considering the amount I ended up spending, I feel I probably should have spent more on the actual drivers.
You could definitely save some money by gluing all panels together and paint it instead of veneer. This would speed up the process from procuring to listening exponentially.
I will try to remember to scan the drawing of detailed dimensions when I get back to work, If I forget remind me.
Too true!
I'm painting mine and it's still taking a while. 😛
Looking forward to it when you get the time. 🙂
Nice job vovo and Ralph will be proud. You'll have to send him a link to show him one of his creations has come to life.
Like Ted, I'm interested in how they sound. They should have similar sonics to the Richter Harlequin MkII which was a highly regarded speaker and won some awards IIRC.
Like Ted, I'm interested in how they sound. They should have similar sonics to the Richter Harlequin MkII which was a highly regarded speaker and won some awards IIRC.
Hi Guys a bit of a query.
I have twice put my amp (640A V2) into protection mode (over voltage / over current). The impedance across the terminals is measured at 6.3 Ohms which is reasonably accurate.
Working on the fact that my amp supplies roughly 75W into 8ohm we should be getting about 90W here. So I should be able to go pretty damn loud but I have cut into protection before achieving that "they should be able to hear this in the next suburb feeling"
once I was using an ipod and the other time I was using my laptop, the volume on both these devices was turned right up, but the amp only got to max 3/4 volume. Could it be that I was amplifying an amplified signal but shouldn't this cause clipping not over current / voltage?
Also for anyone interested, Ralph has suggested either filling the speakers with some sand or shortening the port due to the fact that I have the speakers sitting on wooden floorboards.
I have twice put my amp (640A V2) into protection mode (over voltage / over current). The impedance across the terminals is measured at 6.3 Ohms which is reasonably accurate.
Working on the fact that my amp supplies roughly 75W into 8ohm we should be getting about 90W here. So I should be able to go pretty damn loud but I have cut into protection before achieving that "they should be able to hear this in the next suburb feeling"
once I was using an ipod and the other time I was using my laptop, the volume on both these devices was turned right up, but the amp only got to max 3/4 volume. Could it be that I was amplifying an amplified signal but shouldn't this cause clipping not over current / voltage?
Also for anyone interested, Ralph has suggested either filling the speakers with some sand or shortening the port due to the fact that I have the speakers sitting on wooden floorboards.
I realise I probably posted this at an too obscene an hour to reach the intended audience, so we will try again at a more acceptable hour.
Hey Vovo.
I also have the 640A v2 and have driven it to protection mode many times whilst developing the xo's for my MTM's.
This amp has a allot of protection features and has probably saved me a small fortune.
When you say you checked the impedance, did you mean you plotted the impedance from 20Hz to 20kHz or you used a DMM and checked DC resistance at the terminals?
This amp will start shutting down at around 2ohm loads which I feel is a good thing 🙂
Cheers
Dean
I also have the 640A v2 and have driven it to protection mode many times whilst developing the xo's for my MTM's.
This amp has a allot of protection features and has probably saved me a small fortune.
When you say you checked the impedance, did you mean you plotted the impedance from 20Hz to 20kHz or you used a DMM and checked DC resistance at the terminals?
This amp will start shutting down at around 2ohm loads which I feel is a good thing 🙂
Cheers
Dean
I just used a DMM to check the impedance across the terminals, my electrical knowledge is reasonable but not super is there something I should know?
Hi Vovo the crossover and speakers form a complex impeadance which is not equal at all frequencies. The DC resistance is just that. The resistance at DC, the ac resistance will vary with freq and at some points may be much lower than the DC resistance. This can upset an amplifier.
You really need to measure the impedance of the whole system to know what the minimum resistance of your crossover/speaker combination is 🙂
Also Is one of the protection features of your amp to detect clipping? It might well be (and if it is it has probably saved your tweeters). 3/4 volume sounds about right (certainly the case for my amp) for the point where it will start clipping with a CD level signal 🙂
Tony.
You really need to measure the impedance of the whole system to know what the minimum resistance of your crossover/speaker combination is 🙂
Also Is one of the protection features of your amp to detect clipping? It might well be (and if it is it has probably saved your tweeters). 3/4 volume sounds about right (certainly the case for my amp) for the point where it will start clipping with a CD level signal 🙂
Tony.
vovo
You may want to check with a CD player or similar as a source first as some of portable devices or computer cards can output some odd levels and output impedance as a lot if not most are setup for headphone use and do not behave the same as a regular Hi Fi source component.
The Cambridge would be expecting a source with a max output voltage of 1V-2V which is kind of the standard on CD players. Usually these amps go flat out just after the 1 o'clock position as they have bags of gain and probably approaching 35-40dB. Add a higher SPL speaker and it's even lower and there are users getting heaps of volume around 9 o'clock and complaining about lack of fine volume control. The volume level gives no indication of power output and clipping can happen half way or less. I don't know what devices are used in the Cambridge and sure they are not a LM3886 (IIRC) chip like the lower powered brother, the 340A.
These speakers would have an SPL of around 89dB, would have around a 6R nominal impedance and should not drop below 4R, so should be an easy load on any amp. I'll have to check when I get my main computer going as that has all the modelled info. At the moment I'm using an old 1999 notebook with dial up and it's a PITA.
Do try another source as these should go plenty loud and I'm sure shouldn't get past 12 o'clock on these speakers. Check the crossover as a check just to be sure and safe.
You may want to check with a CD player or similar as a source first as some of portable devices or computer cards can output some odd levels and output impedance as a lot if not most are setup for headphone use and do not behave the same as a regular Hi Fi source component.
The Cambridge would be expecting a source with a max output voltage of 1V-2V which is kind of the standard on CD players. Usually these amps go flat out just after the 1 o'clock position as they have bags of gain and probably approaching 35-40dB. Add a higher SPL speaker and it's even lower and there are users getting heaps of volume around 9 o'clock and complaining about lack of fine volume control. The volume level gives no indication of power output and clipping can happen half way or less. I don't know what devices are used in the Cambridge and sure they are not a LM3886 (IIRC) chip like the lower powered brother, the 340A.
These speakers would have an SPL of around 89dB, would have around a 6R nominal impedance and should not drop below 4R, so should be an easy load on any amp. I'll have to check when I get my main computer going as that has all the modelled info. At the moment I'm using an old 1999 notebook with dial up and it's a PITA.
Do try another source as these should go plenty loud and I'm sure shouldn't get past 12 o'clock on these speakers. Check the crossover as a check just to be sure and safe.
Sanded down my wood today, ready for assembly in less then a week (hopefully). 🙂
They don't look half as bad as I thought they would, but still twice as bad as I initially hoped. 😛
Really keen and glad im progressing!
They don't look half as bad as I thought they would, but still twice as bad as I initially hoped. 😛
Really keen and glad im progressing!
Congrats Matt, it is certainly a helluva job.
Rabbitz, What exactly would I check on the crossover and how? haven't tested it with a cd player, as I don't have one, might have to borrow an xbox just to try
Rabbitz, What exactly would I check on the crossover and how? haven't tested it with a cd player, as I don't have one, might have to borrow an xbox just to try
Just make sure the crossover is wired correctly and check all connections to ground. Can be any source such as a tuner, CD, DVD etc.... something with a fixed voltage output.
I had a problem with an iMac sound output that was clipping (distorting) heavily before it arrived at the power amp so the iMac volume had to be reduced.
This speaker should have a highish SPL and it's a bit puzzling. You may want to check settings in the Notebook etc and try it at say half max volume and check and equaliser settings.
Hope you work this out soon as they should work well even with Notebooks etc.
I had a problem with an iMac sound output that was clipping (distorting) heavily before it arrived at the power amp so the iMac volume had to be reduced.
This speaker should have a highish SPL and it's a bit puzzling. You may want to check settings in the Notebook etc and try it at say half max volume and check and equaliser settings.
Hope you work this out soon as they should work well even with Notebooks etc.
vovo
Got around to looking at the crossover information and this speaker is 6R nom with 4R3 min and 12R6 max. Impedance phase sits between ± 21°. SPL is 88dB.
All this means it should be an easy load for almost any amp and a doddle for the Cambridge.
Got around to looking at the crossover information and this speaker is 6R nom with 4R3 min and 12R6 max. Impedance phase sits between ± 21°. SPL is 88dB.
All this means it should be an easy load for almost any amp and a doddle for the Cambridge.
sounds good, I'll give it a crack with a CD player if it does it again, then it must be the crossovers.
Otherwise, the speakers sound great, really impressed, they lack a bit of kick. Ralph has told me how to sort that out (because I have wooden floorboards) would books perform a similar job to sand for reducing volume?
Otherwise, the speakers sound great, really impressed, they lack a bit of kick. Ralph has told me how to sort that out (because I have wooden floorboards) would books perform a similar job to sand for reducing volume?
The sand decreases the volume as well as adds mass. You can also do that with timber blocks, bricks etc. What the reduced volume does is make the box tuning higher which in turn adds a little hump to the bottom end so it has more kick and and an impression of more bass.
Decreasing the port length as Ralph has suggested does the same job as it also makes the box tuning higher. There's no rule to say the roll off has to be flat and I've used a shorter port on several designs as it can help with BSC at the bottom end. What this does is roll off the bass steeper and lose extension but you'd be hard pressed to hear it. When done correctly you can get a lower F3 but lose out on say F6 or F10. It's all part of the tuning to suit your room, tastes and equipment.
If the speaker sounds great then your crossover would be fine as incorrect wiring really sticks out like dogs balls and sounds off.
It's good to see a listening impression of these speakers.
Decreasing the port length as Ralph has suggested does the same job as it also makes the box tuning higher. There's no rule to say the roll off has to be flat and I've used a shorter port on several designs as it can help with BSC at the bottom end. What this does is roll off the bass steeper and lose extension but you'd be hard pressed to hear it. When done correctly you can get a lower F3 but lose out on say F6 or F10. It's all part of the tuning to suit your room, tastes and equipment.
If the speaker sounds great then your crossover would be fine as incorrect wiring really sticks out like dogs balls and sounds off.
It's good to see a listening impression of these speakers.
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