size issue
Hello, i wonder if i could have a little advice please, having built iBIB for a fostex 127 and this weekend cut the metronome for the hemp fr8c they both have failed to pass SWMBO aesthetics test and earn residence in the lounge due to their size.
I have not glued the metronomes yet, are there any modifications that could be done to drop a little height or make them smaller ?
I believe the internal volume is approx 79.4 litres using the dimensions from the planet 10 table and have read "Feel free to play with the aspect ratio of the start & finish rectangles -- make sure you leave enough room to mount the driver & fit the magnet."
I think i already know that there is not going to be a substantial change so would like to hear some suggestions for another design and reuse some of the wood, eg the Demetri ?
What drew me to the hemp metronomes were the reports of fantastic imaging and full sound without being too heavy on the bass. How do the Demetris preform in comparison ?
thanks in advance for any help
Hello, i wonder if i could have a little advice please, having built iBIB for a fostex 127 and this weekend cut the metronome for the hemp fr8c they both have failed to pass SWMBO aesthetics test and earn residence in the lounge due to their size.
I have not glued the metronomes yet, are there any modifications that could be done to drop a little height or make them smaller ?
I believe the internal volume is approx 79.4 litres using the dimensions from the planet 10 table and have read "Feel free to play with the aspect ratio of the start & finish rectangles -- make sure you leave enough room to mount the driver & fit the magnet."
I think i already know that there is not going to be a substantial change so would like to hear some suggestions for another design and reuse some of the wood, eg the Demetri ?
What drew me to the hemp metronomes were the reports of fantastic imaging and full sound without being too heavy on the bass. How do the Demetris preform in comparison ?
thanks in advance for any help
Attachments
Should be similar in many respects. You can't cut the height down because the length is part of the resonant tuning -the aspect ratio refers to the WxD dimensions.
The iBIB isn't especially big, so it sounds like your partner isn't going to be too keen on anything other than B£$e unfortunately, so I'd probably check in advance in case Dimitri is too wide.
The iBIB isn't especially big, so it sounds like your partner isn't going to be too keen on anything other than B£$e unfortunately, so I'd probably check in advance in case Dimitri is too wide.
Scottmoose said:
Well you can loose about 3" by sticking the port out the back, and loosing the arched open area at the bottom. This would also marginally decrease the footprint.
The Monoliths (Mileva & Demetri) started out in concept as a folded Metronome specifically to contribute to WAF. When you stand next to Demetri it doesn't seem that small, but it is less than a meter tall... Mileva is quite diminuative.
The FR8c is not ever going to fit into a really small box, i have successfully shoehorned FE127 into 4.5 liters (ie LS3/5A sized box -- with FE127eN they destroyed the LS3s we had by here (and soon we'll bring up a pair of Spendor BC1s for a compare))
dave
series resistance
Recently finishing my finals, I have gotten a chance to go back and tinker with my metronomes a little, and have good news: The internal damping and series resistance seem to have tamed the upper mids and improved the overall tone of the speakers tremendously!
In the end, I wound up lightly stuffing the upper portion of the cabinet (above and behind the driver) and adding 9 ohms of series resistance. I have also decided not to use BSC, which does what it should, raise the bass in proportion to the mids and treble, but it seems to also have a muffling effect on the entire range; not enough highs comparatively. perhaps I will revisit BSC at a later date- as I was not able to test BSC with the series R in place... (guess where the 9 ohms came from
)
I have not modified the drivers yet, but still consider doing so at a later date...
I hear that phase plugs decrease treble extension while possibly fixing some sibilance that occurs in certain bands, but I feel that the 166's are a tad dark as they are (maybe could use a super tweeter), and cannot sacrifice much more treble than they already have...
I still consider ENABLE as well, but I find it hard to believe that this subtle treatment could have a noticeable impact for someone as inexperienced as me...
On the series R:
I was unable to try the recommended 5 ohms for the simple reason of not having any high power resistors of this value on hand. Instead I tested both the 3 and the 9 ohm from the BSC network. I found that 3 ohms provided a certain improvement, but 9 really made the metronomes sound good- again, I may still try 5 someday (probably soon), and then reassemble the BSC, but I certainly like the sound as it is (however, I need to set the bass knob on ye ole sony ss receiver to about three 'o clock to balance the sound).
I still detect a tad of midrange shout, but I could certainly live with the sound I'm currently getting.
Is there anything to expect in a switch from 9 to 5 ohms besides a little gain in efficiency, and possibly a little more "shout" (being about halfway between 9 and 3) Is this Q compensation nonlinear, in that the difference from 3 to 5 is sonically perceivable, and that from 5 to 9 is not? or perhaps even counterproductive in some way?
again, thanks for all the help!
Recently finishing my finals, I have gotten a chance to go back and tinker with my metronomes a little, and have good news: The internal damping and series resistance seem to have tamed the upper mids and improved the overall tone of the speakers tremendously!
In the end, I wound up lightly stuffing the upper portion of the cabinet (above and behind the driver) and adding 9 ohms of series resistance. I have also decided not to use BSC, which does what it should, raise the bass in proportion to the mids and treble, but it seems to also have a muffling effect on the entire range; not enough highs comparatively. perhaps I will revisit BSC at a later date- as I was not able to test BSC with the series R in place... (guess where the 9 ohms came from
)I have not modified the drivers yet, but still consider doing so at a later date...
I hear that phase plugs decrease treble extension while possibly fixing some sibilance that occurs in certain bands, but I feel that the 166's are a tad dark as they are (maybe could use a super tweeter), and cannot sacrifice much more treble than they already have...
I still consider ENABLE as well, but I find it hard to believe that this subtle treatment could have a noticeable impact for someone as inexperienced as me...
On the series R:
I was unable to try the recommended 5 ohms for the simple reason of not having any high power resistors of this value on hand. Instead I tested both the 3 and the 9 ohm from the BSC network. I found that 3 ohms provided a certain improvement, but 9 really made the metronomes sound good- again, I may still try 5 someday (probably soon), and then reassemble the BSC, but I certainly like the sound as it is (however, I need to set the bass knob on ye ole sony ss receiver to about three 'o clock to balance the sound).
I still detect a tad of midrange shout, but I could certainly live with the sound I'm currently getting.
Is there anything to expect in a switch from 9 to 5 ohms besides a little gain in efficiency, and possibly a little more "shout" (being about halfway between 9 and 3) Is this Q compensation nonlinear, in that the difference from 3 to 5 is sonically perceivable, and that from 5 to 9 is not? or perhaps even counterproductive in some way?
again, thanks for all the help!
Hi Tony
Glad to see the Mets are working reasonably well.
On the subject of phase plugs: what I found mine did with my FE108ES units was that they
smoothed out the transition to the high frequencies. So although the plugs may give the impression of less HF, compared to the standard drivers, they actually seem to smooth out the peakiness at the top end, giving a much more natural sounding presentation.
Treble air is still there and the extension does not seem to have suffered with my units. Harshness and shoutiness has completely disappeared; unless the drivers are pushed beyond their xMax.
I would not dismiss phase plugs just yet although trying to hear a set of drivers with them fitted might be difficult. You just have to make a leap of faith with them. I spent a week staring at mine before plucking up the courage to get out the scalpel.
Steve
Glad to see the Mets are working reasonably well.
On the subject of phase plugs: what I found mine did with my FE108ES units was that they
smoothed out the transition to the high frequencies. So although the plugs may give the impression of less HF, compared to the standard drivers, they actually seem to smooth out the peakiness at the top end, giving a much more natural sounding presentation.
Treble air is still there and the extension does not seem to have suffered with my units. Harshness and shoutiness has completely disappeared; unless the drivers are pushed beyond their xMax.
I would not dismiss phase plugs just yet although trying to hear a set of drivers with them fitted might be difficult. You just have to make a leap of faith with them. I spent a week staring at mine before plucking up the courage to get out the scalpel.
Steve
I've done some nosing around on the Frugal Horn site to find a current Metronome design that might be a close match for a Tang Band W4-1320SD 4" bamboo driver, and it looks like the FE108E Sigma design is a pretty close fit. Dfiierences in speakers : Fs - 75 Hz for Tang Band vs 77 Hz for Fostex, Qts - 0.37 for Tang Band vs. 0.3 for Fostex, and Vas - 5.9 liters for Tang Band vs. 5.7 liters for Fostex. Considering the difference between speakers, does anything need serious tweaking, or could I go ahead and drop the Tang Bands into the Fostex enclosure?
Scott, please try and understand. When i was in university i was housed with chem majors,pre-med,physics and many others. Once i did LSD to see if i could dervrive greater math ,all i ended up with was jibberish(but there was a trend), this was all a controlled study by my classmates.There was no after affects ( however to this day George Bush still reminds me of a retarded Frog?)
(Still a member of the flatland society)
Now what did this do to audio. Absolutly nothing.
ron
(Still a member of the flatland society)
Now what did this do to audio. Absolutly nothing.
ron
Sorry Ron, no offense intended, didn't notice the original remark in GT's tagline above.
Yeah, I well remember BBC TV footage from the '60s covering some psychological experiments with LSD (which has always scared the hell out of me actually) to see what it does on processing functions (inc. an IQ test of all things). Nothing good, that's for sure.
I think Julian Cope quite liked playing / recording on it though...
Yeah, I well remember BBC TV footage from the '60s covering some psychological experiments with LSD (which has always scared the hell out of me actually) to see what it does on processing functions (inc. an IQ test of all things). Nothing good, that's for sure.
I think Julian Cope quite liked playing / recording on it though...
wrenchone said:
Can't see why you could not drop the Tangs into the Fostex enclosure given how close the two drivers are in spec with each other. They might need a slight tweak to the port length but they would probably work just fine.
What is the xMax of the Tang Band driver? and how efficient is it?
I ask because I could very well be interested in doing the same as you if the xMax of the Tang is greater than the Fostex. (0.28mm)
I'm currently thinking of building some bigger cabs but I like the compact size of the original Mets so if I can get more excursion out of some different drivers I might be able to keep the small form factor and go louder than I can at the moment.
Steve
EDIT
It's OK. I managed to find the specs for the driver. with an xMax of 3mm it looks like a great solution. OK....it is 2dB less efficient than the Fostex FE108ES but I can live with that as I use push-pull tube amplification.
What do you think Scott?
Holey Brace Question?
I'm about to build FE127-based Metronomes.
On Dave's plan, it calls for the brace behind the driver to be snug against the back of the driver. This puzzles me. If the brace is rigid (hopefully) and the driver vibrates (as one would expect), wouldn't one just vibrate against the other unless I couple them or load one against the other? And if I should, how should I?
And would it be worthwhile to flare the end of the port?
I'll report back on progress as things, well, progress.
- Carl
I'm about to build FE127-based Metronomes.
On Dave's plan, it calls for the brace behind the driver to be snug against the back of the driver. This puzzles me. If the brace is rigid (hopefully) and the driver vibrates (as one would expect), wouldn't one just vibrate against the other unless I couple them or load one against the other? And if I should, how should I?
And would it be worthwhile to flare the end of the port?
I'll report back on progress as things, well, progress.
- Carl
Re: Holey Brace Question?
The holey brace should rigidly couple the driver to the back of the cabinet. This couples the drivers netwonian forces more tightly to more of the box spreading out the vibrational load imposes onto the cabinet reducing the peak load on any one part of the cabinet. Ideally this energy them falls below the threshold required to exite a box resonance.
If it is a bipole box, the brace couple the drivers so that you get active vibration cancelation,
The brace should be snug but not so snug that you stress the driver basket.
dave
carlseibert said:
The holey brace should rigidly couple the driver to the back of the cabinet. This couples the drivers netwonian forces more tightly to more of the box spreading out the vibrational load imposes onto the cabinet reducing the peak load on any one part of the cabinet. Ideally this energy them falls below the threshold required to exite a box resonance.
If it is a bipole box, the brace couple the drivers so that you get active vibration cancelation,
The brace should be snug but not so snug that you stress the driver basket.
dave
planet10 said:
'Tread carefully for you tread on my dreams' (or some such!).
Here in the UK, for many people, live music is what the BBC OB department say it is... And, what they say it is, was for a long time dependant on LS3-5As.
People in this country have been burned at the stake for lesser heresy than yours.
And I dread to think what might happen on a visit to HK!
Rgds