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September 16, 2014 - 11:34am
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considering a DIY project - thinking about Monacor Drivers
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If you are seriously considering building your own speakers....
....go here....read, read, & read some more.
Then, figure out exactly want you specifically want from your speakers & be sure the rest of your equipment is matched to the needs of the design.
Then....just ask for help.
Everyone will guide you reliably through the most fulfilling journey in audio you could ever experiance.
Just be willing to invest the time, blood & sweat.
You will not regret it.
I promise.
http://www.htguide.com/forum/forumdisplay.php?6-Mission-Possible-DIY
Bill - on the Hill
Practicing Curmudgeon & Audio Snob
- just an “ON” switch, Please –
I have been doing a lot of reading thus far but that is a great forum and seems like an excellent resource. I need to do a lot of digging. I know roughly what I want, I just don't know how to build it, yet.
I would be more than happy to share what I have learned over the years about speaker building.
Bill - on the Hill
Practicing Curmudgeon & Audio Snob
- just an “ON” switch, Please –
When I get to a point where I am drawing up specs for it, I will have questions. I know what I want, I just need to figure out how to build it. I am also noticing - shockingly - people have differing opinions on right and wrong for materials, size, design, etc... so when I can't come to a solid or obvious conclusion, I am most definitely going to ask POV. Thank you very much for the advice thus far.
Unless you plan on going V exotic, the basic cabinet materials are MDF (medium density fiberboard) or Baltic Birch ply.
Either can be used with V good results.
Bamboo is the new boutique material for DIY cabinets, but be prepared to cash in your 401k for anything bigger than small bookshelf sized units.
Some have reported good luck using properly sized bamboo cutting boards, even if just for the front baffle (where rigidity is of the utmost importance).
Bill - on the Hill
Practicing Curmudgeon & Audio Snob
- just an “ON” switch, Please –
No exotics for me. I was planning on MDF and applying a veneer to get the right look for sides and back but the baffle is what I am uncertain of. Is the Baltic birch plywood superior, particularly for the braffle? Is it superior to MDF even for the sides and back or is it just a push and is whichever you prefer?
My concern with MDF is that I intend to rout a groove into the baffle so the speakers sit flush. I was worried that a reduction in the thickness of the baffle might negatively impact rigidity.
It occurs to me that if I add a few braces from front to back, I could maintain a very high level of rigidity even with MDF. Is that okay to do and if so what material should be used for braces?
I am looking for optimal sound with this
Speakers tend to sound like what they are made of. Baltic birch speakers will sound more alive, MDF will sound more dead, medite (lightweight concrete chipboard) will sound "dense", epoxy bound chipboard will sound somewhere in between MDF and Baltic Birch.
And "Dead" isn't all it's cracked up to be for an enclosure. Well braced will better control the resonant nature of your speaker than just a "dead" enclosure.
A good friend is a high end contractor and can source any wood for me relatively innexpensively. He also has a relationship with a store that does custom installs. I could source something super dense like Mahogany or some of the other tropical exotics. I need about 13 linear feet of 12" plank and at $8 to $10 a linear foot it isn't that expensive. Also, it is easier than getting mahogany veneer since I have no experience veneering something. This would greatly decrease the likelihood I am going to ruin the finish.
Any issue with using an ultra dense wood like mahogany?
Also, these will set relatively close to a wall where if I bought speakers, I would use a port bung. Is it better not to port them in that scenario?
Mahagony will be very difficult to work. Would only be marginally better than white oak - and maybe worse.
You might try to build it with a screw on baffle so you can make your baffle out of a variety of materials and decide which you like most.
Monacor is a German company. Their hi-fi drivers are not widely known and used in the DIY speaker world. It would be safer to opt for drivers from companies like SEAS, Scan-Speak, SB Acoustics, Peerless, Vifa, etc... that have established a good track record in the DIY world with plenty of designs to follow or rework.
The sound of a DIY speaker with drivers in your price range will be strongly influenced by the quality of the crossover and cabinet design.
Yes.
Whether ported or sealed is not an issue. Whether the speaker is designed to work on the wall or out in the room is an issue. A bung is a "hack" for a speaker designed to work out in the room that is then placed near a wall preventing the bass radiating rearwards.
As someone mentioned earlier, you will benefit from finding out a bit about the basics of making a speaker before setting out to design and make one from scratch. Here is a fairly good place to start:
http://techtalk.parts-express.com/showthread.php?219617-The-Speaker-Building-Bible
The site you just sent is great because it has a lot of rudimentary info for DIYers. This pleases me. The more I dig into these forums, the more confused I was getting. Kind of - analysis paralysis.
I know what I want and I think I have a plan on how to produce it. Nice thing is, this sort of eliminates a lot of the silly wheel spinning I was going through like exotic woods.
KISS Principle...
As with many endeavors, it is often beneficial to start out simple, build basic skills & understanding, and then attempt more complex projects.
There are many good beginner-level projects at the PE website & this a great place to start for anyone interested in learning how to build speakers.
They have some more complex designs also.
Overall, I believe, based on my first-hand experience that you find better sounding designs at the HTGuide site I posted earlier, & the Zaph Audio site
http://www.zaphaudio.com/
In most cases these will be more complex & expensive, but deliver more refined & accurate sound.
Regarding cabinet materials, there is little to be gained by using solid hardwoods.
The requirements are rigidity & damping, which are easily achieved with MDF or Baltic birch ply.
Internal bracing is critical.
Some like the Baltic birch ply cuz the birch veneer provides a very attractive base for a handsome looking wood finish.
MDF can be painted or veneered with low cost vinyl or natural wood veneer.
Between the two, the cabinet material choice is one more of a time, skill & cost issue with regards to how one plans on creating the esthetic finish rather than one of performance.
I personally do not like the fine dust created when cutting MDF & because of this prefer the 3/4" 13 ply birch along with other reasons that have little to with the sonic performance.
I highly recommend using pre-assembled and pre-finished speaker enclosures if one is just starting out & has no experience with woodworking.
Many, including Dan & myself, have had good experience with these.
http://www.parts-express.com/cat/hi-fi-speaker-cabinets/288
There are others out there, too.
You can then develop skill using a plunge router with test material prior to cutting the driver openings in the baffle.
Bill - on the Hill
Practicing Curmudgeon & Audio Snob
- just an “ON” switch, Please –
Thank you all for the feedback
I was spending time digging in trying to find "the best" which is highly subjective. I over read and got in a bit of a circle.
The cabinets from Parts Express seem like a really, really good idea. Highly likely that is the way I will go this first time.
I think I might be in a place where I will start shopping for the parts soon. I will pick the drivers and let that decide what size cabinet I will need along with the appropriate crossover.
May I ask.....
What performance goals have you set?
What parameters are you using to steer & judge your driver selection?
Bill - on the Hill
Practicing Curmudgeon & Audio Snob
- just an “ON” switch, Please –
My goal is to deliver 50hz to 60hz on the low end given that it will be a sealed speaker operating near a wall. I like a neutral to slightly warm sounding speaker with a moderate level of detail. I need strong off axis performance because listening conditions will not be optimal.
I am on the fence as to what I am going to power this with. I am considering getting my Carver TFM-15CB and pre-amp refurbed and adding a network player or I may get a Marantz CR510. I will be delivering 60 to 100w of power. It is not a large room, about 10x15 and volume levels will rarely be high so I am comfortable with a pretty inefficient speaker.
I started this strand thinking about Monacor. The specific drivers I mentioned were suggested as potentially strong fit by a friend who owns a stereo store. I have dug into reviews on both items and they are highly regarded.
Do you have any other suggestions?
50 to 60 Hz bottom end will have some roll-off on most any option.
This is the FR on the 2-way Dynaudio X14 as measured by JA.
http://forum.stereophile.com/content/dynaudio-excite-x14-loudspeaker
Red is the woofer, blue the tweeter.
Black is the summed combined FR for both drivers.
From the plot, you can see how quickly the bottom end rolls off.
This is typical for any speaker.
At 50 Hz it is down at least 3 or more dB (than means 3 times quieter than the higher frequencies).
But measured response (at one meter from the driver) typically will not show the extra bass you get from room reinforcement (sound wave interaction with the walls, floor & ceiling).
For realistic bass, anything under 90 - 100 dB will require added bass energy from either bass bins (separate woofer cabinets) or subs to achieve the same equivalent response (dB level).
My point is that you need to keep realistic goals in mind.
I am looking around for some designs that have similar characteristics that you have described.
Good off-axis performance is a feature a good home-theater design has, since the 'sweet-spot' needs to accommodate a wider listening area.
Do not be put off by the 'home-theater' description, as there are many V musical designs with good (wide) off-axis performance.
But it must be incorporated in the design.
Bill - on the Hill
Practicing Curmudgeon & Audio Snob
- just an “ON” switch, Please –
With the mid-bass driver, how deep of a sound will it produce? The only spec I see in these raw drivers is resonant frequency but I am not sure how that relates to actual sound production.
Do the speaker and the tweeter need to have the same SPL? Or maybe I should be asking what is an acceptable gap in SPL? Is this dealt with via the crossover?
Regarding the crossover, I see a MFG spec on the tweeter. I assume that it is critical that there is a nice hefty overlap where the mid-bass driver just goes well above.
Finally, what about power handling? The power rating on some of these drivers is really low and I would be a hair concerned to try and power with a 100w power amp when RMS rating is 40w. Is the power rating on the two speakers supposed to be additive or is it averaged?
Red is the output from the rear port. Blue is the output from the woofer and the tweeter output is not shown separately.
Note the high midrange output through the port. I am surprised Dynaudio haven't done something about this even with a rear rather than front port.
The 24dB/ocatve roll off rate is for a ported speaker. A sealed speaker like the OP proposes will roll off at only 12dB/octave but the -3dB point will be significantly higher in frequency.
-10dB would be perceived as approximately half as loud. I am not wholly sure why -3dB is conventionally taken to mark the frequency response limits perhaps it simply follows from conventional filter analysis.
Indeed. If the OP goes for a 6.5" midwoofer + 1" tweeter then clean deep bass will be absent. A subwoofer, or better a set of subwoofers distributed about the room, will provide this and also clean up the sound from the satellite speakers by removing the large cone movement from the 6.5" midwoofer.
If you are interested in maximising sound quality in a technical sense at a given price point then the best value is almost certainly going to be found with active monitors from the proaudio sector.
Andy, thanks for correcting the information I posted.
I did not read the article or the other charts & thought the there was no port in this speaker.
Being in a hurry & not fact-checking is no excuse, however.
With little to no credibility left at this point, I will refrain from any further comments.
I am not a designer, just a woodworker & speaker builder who relies on the designs & expertise of others for testing & designing.
Bill - on the Hill
Practicing Curmudgeon & Audio Snob
- just an “ON” switch, Please –
Those are remarkable measurements for such an inexpensive, small bookshelf speaker. I still can't believe the LF extension and crossover linearity.
If I wanted Full range speakers, I would build floor standing speakers. I know I will not get deep, clean bass, but I want to get as deep and clean as I can get given the parameter. I know that I will get nothing below a certain frequency, the issue is I can't seem to find any sort of explanation on any site or forum on how to calculate that. If I want a low end of 60hz, how do I choose a driver and make a cabinet that will deliver that? BTW, I did not pick that number arbitrarily. 60hz is the -3dB bass response on my Revel Performa3 M105s and I would be more than pleased if I came close to that.
I am not porting because the speaker will be near the wall.
My friend is going to hand me a set of Monacor SPH-135 KEP. Same speaker but with a 5 1/4" driver and a resonant frequency of 45hz. I am also getting a pair of Monacor n-25 silk dome tweeters. My friend who owns this store is swapping me them for a bottle of Scotch that I don't want or like. It was part of a special order that got miss shipped.
I don't need to use these in this project as this will likely not be my last DIY speakers. I am inclined to because these were evidently pretty expensive speakers. A potential issue I see is that the tweeters have an SPL of 95dB and the drivers have an SPL of 89dB.
If I understand the forums I have read, I need to add an L-pad attenuator to deal with the output difference.
I know the 5 1/4" driver won't give me quite as good of bass response as the 6 1/2" but it is tough to pass up speakers that are effectively free saving me like $400
As I mentioned above, download the WinISD program, type in the parameters for your drivers and you will be able to compare frequency response, SPL limits and more for different cabinet types and sizes.
As I mentioned above, porting is irrelevant to near wall. What is relevant is the baffle step correction, or lack of it, in the crossover. And the distance of the woofer from the rear wall. And...
If you enter the driver parameters into WinISD you will see this driver is designed for something like a small ported desk speaker.
Even with the drivers for free it is likely that a DIY speakers at this price point is still going to cost more that buying a complete commercially mass produced equivalent. DIY speakers also have little resale value compared to a branded speaker. If your main motivation for DIYing speakers is not fun and interest then I would suggest forgetting it.
That seems to be the missing link and will answer my questions.
I am DIYing because it is interesting and it seems like a good way to learn more.
http://audio.claub.net/software/kougaard/ubmodel.html
http://www.linearteam.dk/default.aspx?pageid=winisdpro
Both of the links from here: http://www.htguide.com/forum/showthread.php?42190-FAQ-s-amp-Reference-Websites-You-Should-Read!
Bill - on the Hill
Practicing Curmudgeon & Audio Snob
- just an “ON” switch, Please –
I will be downloading and in a perfect world, will be placing my order for parts shortly. The real question is whether I will use the Monacor drivers I have or if I will be ordering new ones. But I will let the software tell me that.
I posted a picture of them over in galleries since I can't seem to figure out how to insert an image in the text here.
http://www.stereophile.com/content/first-diy-speakers
I opted to build them using the Monacor drivers that I had and am very happy. I opted for the pre-fab Dayton Audio .38 cu ft curved cabinets from parts express. I selected the Dayton 2.5khz crossover and Dayton binding posts. The one thing I did opt to do was to add the L-pad attenuator due to the differential in SPL between the tweeter and woofer. Now that I have it tuned in, the L-Pad volume is very low which makes sense due to the 6dB difference in SPL.
The software said I should get a 62hz output at -3dB. I don't have the right microphone for measurement but the initial numbers came back at 65hz to 72hz on the three passes. When I get the correct microphone, I will take full measurements and post them.
I am extremely happy. They sound great - the Monacors remind me of Bowers and Wilkins speakers in sound. Very detailed and extremely neutral which is what I was hoping for. It took some time to get them dialed in with the attenuator, but I could not be happier. They sound great off axis and really fill the room.
I have posted the photo with my old Carver Equipment. Wife likes the speakers, hates the Carver equipment - too big. Looks like I am going the be getting a Marantz M-CR510 to power them. Trying to decide if I am going to build or buy a nicer subwoofer than the POS Polk I have lying around.
Thanks to everyone who offered advice here. It is very cool to have completed this project.
I copied your photo from the 'Gallery' post.
They look great!
Glad to hear you are happy with the performance.
Bill - on the Hill
Practicing Curmudgeon & Audio Snob
- just an “ON” switch, Please –
The Monacor speaker you are referencing in a fabulous driver. I have the 5 1/4" version in a small bookshelf enclosureS with dome tweeters and they sound AMAZING! I've listened to music on these that I've listened to for decades & hear things in the original recordings that I'd never heard before. Don't hesitate to use them. I've had people swear I'm running a small sub in the room & it's only the two small bookshelf speakers. Music sounds very "live" like the band is right in front of you playing. You won't regret buying them
This project turned out WAY better than I expected and those drivers and tweeters are amazing. I used Dayton parts. Excellent speakers.