Jim's description of the sound of his Metronomes matches my impressions. Against the wall there was no evidence of a baffle step problem, no rising response and solid bass, but the speakers only sounded OK. Once Jim moved them into the room a little and added the BSC filter, that I had brought with me, the sound really improved exactly as he described.
I had used a variable resistor so we tried two different settings. The first setting worked best, a 1 mH ERSE 14 AWG air core inductor in parallel with abuot 2.5 ohms of resistance in the positive speaker lead. Increasing the resistance did not sound as good.
With the BSC filter and Jim's sub, filling in the very bottom below 40 Hz, the system really sounded great. Getting 40 - 50 Hz from a relatively small enclosure with the Fostex FE-108EZ driver is quite an accomplishment. The Metronime concept is a winner in my book.
I had used a variable resistor so we tried two different settings. The first setting worked best, a 1 mH ERSE 14 AWG air core inductor in parallel with abuot 2.5 ohms of resistance in the positive speaker lead. Increasing the resistance did not sound as good.
With the BSC filter and Jim's sub, filling in the very bottom below 40 Hz, the system really sounded great. Getting 40 - 50 Hz from a relatively small enclosure with the Fostex FE-108EZ driver is quite an accomplishment. The Metronime concept is a winner in my book.
But double the enclosure volume and double the cost of the drivers. For the cost of the two drivers per side, could one buy a better single driver per side and add a BSC filter? I know you are not a fan of the BSC filter, but I am not sure that the bipole concept has a clear cut advantage. There are always trade offs and compromises.
Steve,
If you look at the placement of my speakers back in post #41, you will see that both speakers are 2” from the wall. The left speaker is 18” from an in-wall bookcase, while the right is 8” from the doorway into the kitchen/dinning area. Using Stereophile's Test CD, I checked the output levels at several frequencies at 1 meter in front of each speaker. Measurements are made without the BSC circuit, which should make no difference in this limited range anyway.
The graph below shows that the output rises under 200 Hz for both speakers: Left = series 1; right = series 2. The left speaker shows a greater effect than the right. Just to be sure that it was due to the placement and not a difference between the drivers, I swapped the speakers and re-tested: same result.
(OK guys, how do I get the graphs out of Excel & into a post?)
Moving the speakers out to 12" from the wall, I re-ran the test.
(graph goes here)
My conclusion, stating what is probably obvious and already known: The wall to speaker distance will effect response, but the difference between 2" and 12" isn't enough to bother about. Which isn't too surprising when one considers that at 100 Hz the wavelength is almost 11 ft. In the graphs, you can see the effect of a second boundary (the in-wall bookcase.) Based on the difference between the single boundary and the dual boundary, it looks to me like if there were no boundaries, the response would be close to flat. I will say that in listening, it is obvious that the left speaker produces more bass than the right, just as is indicated in the graphs. If more mid-bass is what you want, then placing a Metronome near a corner will get you what you there. On the other hand, if you are trying to get a 'fuller' sound, then you need to add a sub for the bottom octave. For me, there is enough music which reaches below 40 Hz to justify the addition of a small sub.
And going back to the previous discussion of BSC: In spite of the low freq reinforcement by room boundaries, I prefer the sound with the BSC. The BSC seems necessary to tame the highs. Moving the speakers away from the wall improves imaging and soundstage as well. The difference is not subtle!
Bottom line: I love these Metronomes!
Cheers, Jim
If you look at the placement of my speakers back in post #41, you will see that both speakers are 2” from the wall. The left speaker is 18” from an in-wall bookcase, while the right is 8” from the doorway into the kitchen/dinning area. Using Stereophile's Test CD, I checked the output levels at several frequencies at 1 meter in front of each speaker. Measurements are made without the BSC circuit, which should make no difference in this limited range anyway.
The graph below shows that the output rises under 200 Hz for both speakers: Left = series 1; right = series 2. The left speaker shows a greater effect than the right. Just to be sure that it was due to the placement and not a difference between the drivers, I swapped the speakers and re-tested: same result.
(OK guys, how do I get the graphs out of Excel & into a post?)
Moving the speakers out to 12" from the wall, I re-ran the test.
(graph goes here)
My conclusion, stating what is probably obvious and already known: The wall to speaker distance will effect response, but the difference between 2" and 12" isn't enough to bother about. Which isn't too surprising when one considers that at 100 Hz the wavelength is almost 11 ft. In the graphs, you can see the effect of a second boundary (the in-wall bookcase.) Based on the difference between the single boundary and the dual boundary, it looks to me like if there were no boundaries, the response would be close to flat. I will say that in listening, it is obvious that the left speaker produces more bass than the right, just as is indicated in the graphs. If more mid-bass is what you want, then placing a Metronome near a corner will get you what you there. On the other hand, if you are trying to get a 'fuller' sound, then you need to add a sub for the bottom octave. For me, there is enough music which reaches below 40 Hz to justify the addition of a small sub.
And going back to the previous discussion of BSC: In spite of the low freq reinforcement by room boundaries, I prefer the sound with the BSC. The BSC seems necessary to tame the highs. Moving the speakers away from the wall improves imaging and soundstage as well. The difference is not subtle!
Bottom line: I love these Metronomes!
Cheers, Jim
MJK said:
Well I'm talking out of my a$$ regarding the Metronome specifically, which I've heard for only the first time this weekend, but I have built or listened to a few mono / bipole variations of similar enclosure designs. Since embarking on DIY speaker construction about 8 years ago, I'll readily acknowledge the evolution of a "bias" for a certain flavor that has been achievable without "EQ" (which came first, my resistance or acceptance?....)
Of course all audio systems contain compromises, and but so far it has been my experience that in the right room, there are advantages to bipole, OB, and BLH designs with rear firing terminus (is the plural termini?) beyond just the mitigation of need for BSC filters.
We've talked this point before, and yup, I need to try it one time with a SS amp as you suggest - but unfortunately I've yet to hear one recently that satisfies as easily as tubed amps. Several flavors of chip amps, the DIYAudio group buy mini-aleph, Trends T-amp, and of course any locally available commercial product I could possibly afford have all left me cold.
Jim Shearer said:
Glad you like them Jim. I have reinstated my sub after reading about how you set yours up.
I have an MJ Acoustics Pro 50 active sub. Previously I had the crossover set too high. Now set at 40Hz and on a very low volume setting it fills out the sound nicely and adds a degree of subtle ambience to the music
Steve
I whole heartedly endorse the use of a properly balance sub. When done right, a sub isn't noticed--the speakers just seem to be a bit larger &, as you say, the ambience in the recording comes out. Many folks dislike subs because of what they hear in HT set-ups.
(I'm still trying to figure out how to get the graphs from Excel into a post. I may have to print them, then scan them in. What I probably need to do is talk to a teenager!)
Cheers, Jim
And again, thanks!
(I'm still trying to figure out how to get the graphs from Excel into a post. I may have to print them, then scan them in. What I probably need to do is talk to a teenager!)
Cheers, Jim
And again, thanks!
Steve Cresswell said:
Hi Guys,
I should be buttoning-up my 108 ES Mets up within a day or so, FWIW I built them 2" X 3" internally at the top as suggested by Steve. Before closing them up I want to be clear on the current lining/stuffing recommendations.
As I understand it now, a good starting point is:
No lining at all
A bit of polyfil or wool batting above the driver
Perhaps a bit of acoustic foam behind the driver
Comments/Suggestions?
Thanks!
I certainly concur w/ Steve, although I am hardly experienced enough to speak on the subject.
I assume you will be 'closing up' such that you can 're-open' the enclosure for further work. I learned that one the hard way! When I re-build the enclosures (so that they are properly done in both function & appearance) I will make the port baffle easily removable. Martin informed me that the pressure at the large end of the 'tube' is just about zero, so the port tube and the baffle itself only need to fit snuggly, not be hermetically sealed.
And I will be eager to hear how you like the sound of your Metronomes. I'm lovin' mine!
Just for the record: from Martin's recommendation, I made the BSC circuit w/ a 1 mH inductor and a 3 ohm non-inductive resistor; no zobel network needed w/ the FE108 E sigma; I may try upping the resistor to 3.5 ohms to try that later.
Cheers, Jim
I assume you will be 'closing up' such that you can 're-open' the enclosure for further work. I learned that one the hard way! When I re-build the enclosures (so that they are properly done in both function & appearance) I will make the port baffle easily removable. Martin informed me that the pressure at the large end of the 'tube' is just about zero, so the port tube and the baffle itself only need to fit snuggly, not be hermetically sealed.
And I will be eager to hear how you like the sound of your Metronomes. I'm lovin' mine!
Just for the record: from Martin's recommendation, I made the BSC circuit w/ a 1 mH inductor and a 3 ohm non-inductive resistor; no zobel network needed w/ the FE108 E sigma; I may try upping the resistor to 3.5 ohms to try that later.
Cheers, Jim
Thanks Guys,
Yes, I did plan on making the bottom removable, just in case
I'll be sure to let you know how things turn out. Currently, I have Bob Brines' FT-1600 MKII which is what got me hooked on full rangers in the first place The MKII's are great speakers but I'm trying to find something that sounds great in a visually smaller package. To that end I did build Bob's FB-16's but just couldn't get them to integrate with my sub very well, there was always a hole in the low end somewhere I have high hopes for the Mets.
Yes, I did plan on making the bottom removable, just in case
I'll be sure to let you know how things turn out. Currently, I have Bob Brines' FT-1600 MKII which is what got me hooked on full rangers in the first place
The MKII's are great speakers but I'm trying to find something that sounds great in a visually smaller package. To that end I did build Bob's FB-16's but just couldn't get them to integrate with my sub very well, there was always a hole in the low end somewhere I have high hopes for the Mets.Thought I'd chip-in again. What with all this talk of *not* lining the cabinets I took out the carpet underlay (apart from the top 6" which was impossible to reach) from inside my FE127E metronomes. My Mets have always produced lots of low end, but they are corner loaded in a small room and sit on a wooden floor.
Taking out the lining freed up the sound somewhat (better mids) but the bass has started to boom. JohninCR mentioned that his Mets were sensitive to positioning, getting boomy near walls, but a bit of back-filling should be all it takes to fix this. I'll report back...
Cheers all,
gus
Taking out the lining freed up the sound somewhat (better mids) but the bass has started to boom. JohninCR mentioned that his Mets were sensitive to positioning, getting boomy near walls, but a bit of back-filling should be all it takes to fix this. I'll report back...
Cheers all,
gus
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.