Revel M105 Copy DIY build

[TulseLuper]

PDF attached. This is based on McFly's drawing, not my own build. Done in Fusion360, happy to send a design file if anyone wants it. Some notes:

- Waveguide and Woofer cutouts in the baffle are extruded from the units actual 3d models. When I cut, I add a 1/2 mm or something on my CNC router (the Shaper Origin) so the drivers fit in more easily.
- I did not put port/binding post cutouts in the back because no specific model is called for or needed.
- Goes without saying, but if you use a Precision Port, imagine the tube extending closer to the tweeter.
- Brace height is whatever you want but in this drawing it is at the edge of a small chamfer on the back of the woofer cutout.
- You might consider raising drivers by 1-2mm so the gap at the bottom of the baffle matches the gap at the top. Here, it's 24mm on the bottom and almost 26 on the top.
- My speaker weighs 20lbs (9kg)

 

[TulseLuper]

Have you been able to do some critical listening to the speakers?

I just got home last night and finished one speaker this morning. The drivers seem to be playing their assigned range. Sounds quite good to me right now after very brief listening session with one unit. I'm pretty busy atm but will be able to do a basic couple of measurements to confirm it matches McFly's expectations. And will report back when I've listened more.

These are being shipped out to California, and I don't plan to install the woofers before that. Since I'm shipping anyway, I could send one to Amir on the way to CA if McFly approves and Amir/the community care enough. I understand he's buried in speakers though.

 

[zman01]

TulseLuper,

Thanks for sharing CAD drawings.

My vote is for getting these measured by ASR once McFly is ready.

 

[McFly]

PDF attached. This is based on McFly's drawing, not my own build. Done in Fusion360, happy to send a design file if anyone wants it. Some notes:

This is above and beyond! I never expected this. I owe you a beer.

- Waveguide and Woofer cutouts in the baffle are extruded from the units actual 3d models. When I cut, I add a 1/2 mm or something on my CNC router (the Shaper Origin) so the drivers fit in more easily.

Agreed.

- I did not put port/binding post cutouts in the back because no specific model is called for or needed.

Agreed. Indeed binding posts/cups/terminals are designers choice

- Brace height is whatever you want but in this drawing it is at the edge of a small chamfer on the back of the woofer cutout.

Agreed. What I also should have mentioned (and I will try and remember to get in some photos) was the chamfer on the midbass cut out. I did quite a substantial one I think 15mm 45deg due to the thick baffle. One forgets to mention the things they do automatically when building speakers... heh

- You might consider raising drivers by 1-2mm so the gap at the bottom of the baffle matches the gap at the top. Here, it's 24mm on the bottom and almost 26 on the top.

110% - in fact I'd encourage it. It's what I was gunning for - 25mm top and 25mm bottom, however pinpoint precision with the waveguide routing was difficult for me, and these speakers were not built as final revisions. Moving the drivers 1 or 2mm will not hurt the crossover much at all.

- My speaker weighs 20lbs (9kg)

More perceived value in weight /s

I just got home last night and finished one speaker this morning. The drivers seem to be playing their assigned range. Sounds quite good to me right now after very brief listening session with one unit. I'm pretty busy atm but will be able to do a basic couple of measurements to confirm it matches McFly's expectations. And will report back when I've listened more.

These are being shipped out to California, and I don't plan to install the woofers before that. Since I'm shipping anyway, I could send one to Amir on the way to CA if McFly approves and Amir/the community care enough. I understand he's buried in speakers though.

Excellent to hear you have the ability to measure. Please send me whatever result you get so we can peer review. I should be able to help if anything is odd, hopefully.

Re NFS scan - I been thinking about that a bit. I don't know if it's at the stage where it's worth putting through a NFS test just yet. Sure we could, and if it's okay, great! But if its not, it sorta tanks the project, and you gotta remember, I'm an amateur designer - see disclaimer in post 1. M105C never got the same level of scrutineering and design work that the Directiva got, or the same amount of widespread "peer-review", for lack of a better word, that other known established DIY designs have had.

Sure, if an NFS operator was willing to put in the time to measure each driver individually and send me the files so I could have another crack at the crossover (if required) thats also great. And if this were the case, I'd advocate for measuring with and without 25mm round overs if possible. Hell, even if they measured poorly just give us a chance to redo the crossover. Easy enough to do because its DIY and not commercial.

If we get a couple built and people are liking it and getting good results, lets revisit NFS. It's not that I don't have faith in my crossover work. I just don't have full faith in my mics - which means I don't get full faith in the finished crossover, especially when referenced against the gold standard NFS.

And I just wrecked my UMIK. So waiting for that replacement is slowing me down.

 

[TulseLuper]

Listened more today, and I’m really happy with them. They sound basically neutral to me with good clarity and bass ain’t bad at all. Feels like a decently downward-sloped response to me at first. Subjectively, relative to my other DIY speakers (mostly active, wave-guideless 2-ways with x-over points below 2kHz FWIW), it seems more critical to be close to the vertical axis with these.

This is so dumb, but I lost my mic stand. I tried some handheld measurements today but won’t share them due to the shittiness factor. Anyway, on axis looked nice and smooth and sloped down a bit (4-5db drop from 400Hz to 10kHz). Hard to tell, but we definitely have some coverage to 55Hz or so, maybe lower.

Not very helpful, I know. I’ll say I’m happy and would build them again - looking forward to getting all three set up. When I get around to doing better measurements I’ll share them. @McFly I don’t blame you for wanting to see more peer review before the NFS test. But good work here!

 

[D!sco]

Sounds like what Erin did with those DIY speaker kits is what you want with the Revel clone. I miss that guy. Hope he's doing okay.

I don't see why Amir couldn't provide all the necessary data to finalize a kit like this, except that he hasn't yet for any project besides Directiva. This is significantly less expensive and operates on very similar principles, which is why I'm sure so many people like myself have been excited about this since the original post. Seriously @McFly, this is a huge step out of the primordial pool of DIY ideas from flat boxes with drivers stuck on them to manufacturing and tuning your own directivity. Stacking it up against quality products implementing the same philosophies is appropriate and exciting right now.

 

[McFly]

This is so dumb, but I lost my mic stand. I tried some handheld measurements today but won’t share them due to the shittiness factor. Anyway, on axis looked nice and smooth and sloped down a bit (4-5db drop from 400Hz to 10kHz). Hard to tell, but we definitely have some coverage to 55Hz or so, maybe lower.

This is at listening position, I hope? If 1m on axis, we got some issues.

 

[Jopldangla]

New here… and am loving this diy. Quick question. The tweeter is 4ohms and the woofer is 8ohms. What part of the crossover adjusts for the impedance differential (or do you even need to account for the difference).

 

[LTig]

There is no real need to compensate the impedance difference. The crossover must match differences in sensitivity. If the tweeters sensitivity is higher then a serious resistor in front of the tweeter can match both sensitivity and impedance.

 

[mga2009]

Great thread! Thanks @McFly and @TulseLuper !!

Any news on sending a speaker to Amir? That would be an awesome development in the DIY community.

Cheers!

 

[IamJF]

I know the breakup is extended on the SB, but you might try a notch in series with the woofer, and closer to it than the rest of the network. Per Lars at Purifi this will also remove the harmonic distortion related to the breakup. Other forms of filtering do not have this property. I asked specifically about the cap across the first inductor as I like that method a lot. His answer was really technical but amounted to "no".

I tried that with a mid dome - it 100% works.
With a series resistor you dampen the current from the coil at this frequency and the corresponding THD spikes disappear. A passive crossover getting high impedance at this frequency would also work btw - but you can't do that active.

 

[Jopldangla]

What size amp are your using to power these? I have been working on a this design but with a different tweeter. I need to pickup a receiver/amp but wondering how big to go on these.

 

[DanielT]

New here… and am loving this diy. Quick question. The tweeter is 4ohms and the woofer is 8ohms. What part of the crossover adjusts for the impedance differential (or do you even need to account for the difference).

You only need to take into account the dB difference between different divers.

For passive crossover if you want to lower the level of the tweeter. Then you connect resistors in the crossover. You can test yourself to find out what is the appropriate value for them (listen and or measure FR).

Or you buy a passive rotatable attenuator, L-pad attenuator. Note tweeters do not need a lot of power, so this if they are specified for like 15 W is nothing to worry about.. There is plenty to choose from:

MONACOR: Products

L-pad attenuator Level control for speakers Mono version With front panel and knob

www.monacor.com

Edit:
Or you skip the passive crossover altogether and use, for example, an active crossover:

dbx 223xs Crossover Review

This is a review and detailed measurements of the dbx 223xs active analog balanced crossover. It is on kind loan from a member and costs US $245. I must say this is a nice and sturdy package for such a bargain price. Controls feel nice as well. Functionality though is confusing given the...

audiosciencereview.com

Or work entirely in the digital world. If this appeals to you:

RPi4 + CamillaDSP Tutorial

Intent of this thread is to provide a tutorial for setting up CamillaDSP on a RPi4. There is a lot of good information scattered through ASR, DIYAudio and the CamillaDSP GitHub but there also appears to be a lot of apprehension. My goal is to give concrete examples of how to use CamillaDSP with...

audiosciencereview.com

Power bass/mid with one amp tweeter with another amp. Or even four separate amps if you want.

 

[DanielT]

What size amp are your using to power these? I have been working on a this design but with a different tweeter. I need to pickup a receiver/amp but wondering how big to go on these.

Different tweeter you say, but which one? Are you going to assemble it together with a WG that Somasonus developed for that tweeter?

Waveguides | somasonus

www.somasonus.net

Edit:
Regarding suitable power. Here's a thread about that. Plus various links to similar threads with that topic in it:
(subbass requires a LOT of power so skip the calculator for that)

How much power does an amplifier need with this type of range of dynamic music

Feel free to use this calculator. Add sensitivity to the speaker and then tell which effect you have chosen and why. Weigh in that you want some headroom. http://www.mh-audio.nl/Calculators/REAP.html You can select music from this list. Or something else, but in that case tell us how you...

audiosciencereview.com

Because it's almost Christmas, so what I wrote in that thread a few years ago:

About the dynamics of classical music, explained.

It will not be as good as live. But it can be decent anyway and that requires its amplification (if it is recorded with dynamics), from 17:50 and a few minutes ahead into the video when she says: "And the power"

By the way, damn what a singer he was.

 

[Jopldangla]

@DanielT I am pairing the scanspeak with Morel ST1108 tweeters. AugerPro helped me adapt a few of his waveguides to mount the Morel. The Morels are definitely better with the WG than without. (I posted a comparison at the other DIY forum).
I will check out the posts you linked.
Here is a picture of it with my attempt at a waveguide (which wasn’t as good as Augers. I didn’t realize the shape of the WG was not conical but more of a complex/smoothed curvature).

 

[LTig]

You only need to take into account the dB difference between different divers.

For passive crossover if you want to lower the level of the tweeter. Then you connect resistors in the crossover. You can test yourself to find out what is the appropriate value for them (listen and or measure FR).

Or you buy a passive rotatable attenuator, L-pad attenuator. Note tweeters do not need a lot of power, so this if they are specified for like 15 W is nothing to worry about..

If you use an L-pad keep in mind that a tweeter is not a resistive load but has inductivity. If the passive crossover is designed with this inductivity in mind then reducing the volume with an L-pad reduces the influence of the inductivity which may change frequency response.
To circumvent this add a resistor in series with a cap in parallel to the tweeter. This counteracts the inductivity and the tweeter will then look like a pure resisitive load. Then design the crossover for this resistive load and add an L-pad.

Edit:

Or you skip the passive crossover altogether and use, for example, an active crossover:

This!

 

[DanielT]

View attachment 332657@DanielT I am pairing the scanspeak with Morel ST1108 tweeters. AugerPro helped me adapt a few of his waveguides to mount the Morel. The Morels are definitely better with the WG than without. (I posted a comparison at the other DIY forum).
I will check out the posts you linked.
Here is a picture of it with my attempt at a waveguide (which wasn’t as good as Augers. I didn’t realize the shape of the WG was not conical but more of a complex/smoothed curvature).

Aha, that looks good!
It's mostly the concept of the design with the WG and the shape of the baffle which is the same as the first McFly's that had SB drivers. BUT your drivers can probably work just as well. If you get to a crossover that is suitable.

If you use an L-pad keep in mind that a tweeter is not a resistive load but has inductivity. If the passive crossover is designed with this inductivity in mind then reducing the volume with an L-pad reduces the influence of the inductivity which may change frequency response.
To circumvent this add a resistor in series with a cap in parallel to the tweeter. This counteracts the inductivity and the tweeter will then look like a pure resisitive load. Then design the crossover for this resistive load and add an L-pad.

Glad you pointed that out. Missed it.

Speaking of the values of the resistors, the very principle of damping, McFly's first post in this thread he writes (which I know you know of course). That's pretty much what I said earlier. That is, try and test. Listen and or measure microphone.

Note the simulated padding resistor for the tweeter is 3.3 ohms however it is 4.5 ohms as built - I often run into this with vituixCAD and I need to add 0.5 to 1 ohm to my final builds in the high frequencies. Probably a problem with my measurement rig. Either way, you can adjust this value to your taste. Too hot up top? Make it 5 or 5.5 ohms. Like more sizzle? Try the 3.3 ohm. If you're building these I would hope you at least have a UMIK to measure the final result. Driver phase matching isn't affected too much.

 

[Jopldangla]

Aha, that looks good!
It's mostly the concept of the design with the WG and the shape of the baffle which is the same as the first McFly's that had SB drivers. BUT your drivers can probably work just as well. If you get to a crossover that is suitable.


Glad you pointed that out. Missed it.

Speaking of the values of the resistors, the very principle of damping, McFly's first post in this thread he writes (which I know you know of course). That's pretty much what I said earlier. That is, try and test. Listen and or measure microphone.

Note the simulated padding resistor for the tweeter is 3.3 ohms however it is 4.5 ohms as built - I often run into this with vituixCAD and I need to add 0.5 to 1 ohm to my final builds in the high frequencies. Probably a problem with my measurement rig. Either way, you can adjust this value to your taste. Too hot up top? Make it 5 or 5.5 ohms. Like more sizzle? Try the 3.3 ohm. If you're building these I would hope you at least have a UMIK to measure the final result. Driver phase matching isn't affected too much.

I have taken detailed measurements using the UMIK and REW. This has helped me design the cross over. I did measure that one of the tweeters is more sensitive than the other, so I will need to address that with the x-over design. I ended up implementing an LPAD within the cross over to address the Sensitivity issue, but I did this assuming both were the same.

I will say, the x-over and build has great results so far. The clarity and surprisingly good low end is phenomenal. I keep looking at the 5.5" driver and thinking, how is it possible to have such bass from this little guy. When the weather cooperates I will take them outside to collect full spins.

 

[ChargedCapacitor]

I will say, the x-over and build has great results so far. The clarity and surprisingly good low end is phenomenal. I keep looking at the 5.5" driver and thinking, how is it possible to have such bass from this little guy. When the weather cooperates I will take them outside to collect full spins.

I was thinking the same thing about the low end. It outperforms several of my 6.5" woofers, and almost matches the bass output of my Polk R200.

 

[riceFET]

Is it possible to build this with a shallower but taller cabinet? I don't have a lot of desktop space.