Exploring Purifi Woofer Speaker Builds

well I can confirm that it will work. I just hooked it up and blasted some organ and the 2 PRs held up fine even when the Purifi was pumping hard, at parts the Purifi even went beyond xmax, scared the crap out of me.

not much in terms of listening nor impressions as this is before fine tuning.

Ok I lied, here is some prelim impressions. :D I did a little bit of listening last night. Mostly something that has interesting bass. Cello, double bass, organ, and loud orchestral music, and a little jazz.

Firstly, the Purifi really like to be pushed. It has absolute no problem showing off its 10mm xmax. Almost like it is a small subwoofer with the amount of movements. The SB passive radiator on the other hand, is much more mellow in terms of cone movement. But when the low registers of the organ hits, it does dance along as well. The decision to go with 2 PR per side is the correct one as one SB won't survive the onslaught, esp if you value good amount of low bass. I played some jazz pieces with bass guitar, and I managed to bottom out the PR a few times.

As for the sound characteristic, it is really quite interesting. With a flat response down to 40Hz it is very well controlled. There is no boomy bass but instead, very good definition. The amount of bass texture shows up well in cello and double bass, an amount of clarity that I haven't heard before. The usual murky quality of bass is much less. Esp for double bass.

Now it is not loud SPL bass, I have a pair of JBL 15" in the room and no way it will match the type of scale. But despite so, I EQ'ed +3dB below 100Hz and the Purifi responded and did ok to fill my 20x20 room. However, it is not ideal for a large room. The Purifi in a medium room esp with smaller living spaces will be ideal. Or perhaps 2x Purifi on each side. A slim tower will be perfect.
 
Warning: Gush post forthcoming.


I've finished my PR build and much prefer it to the bass reflex box I had before. I ended up around 23L internal with everything installed. It's hard to think that I could get better sound from a bookshelf speaker. Best bookshelf speaker I've heard was the SCM19 from ATC, and the most expensive I've heard was the Dynaudio Contour 20. I've gone way past them with this build I think, but I don't have them here side by side so the usual grain of salt applies. There is also a lot of self satisfaction with DIY, but at this point I will happily say this speaker will be with me for a long long time. I have been listening almost non stop since I completed them and just don't want to stop. The old digging through the record collection again trick. Everything from 35hz to 20khz is there and perfect. It sounds like I have near-field studio monitors but I'm mid to far field and there's that perfect touch of warmth in the bottom end that makes you lean back and enjoy for hours. Studio monitors tend to have you on the edge of your seat and that gets tiring. I am simply amazed by these drivers, and I can play any volume I like up to almost party levels with no audible distortion. If I'm honest I cant even hear distortion before a woofer bottoms out. These are the first bookshelves where the sound stage actually extends out beyond the edges of the speakers, and I mean I keep looking to the left and right in disbelief. I've read about it numerous times but have never experienced it quite like this, so for ages I was trying to figure out what was wrong as I was certain the phase was reversed somewhere or something. The main system has never done it. Probably a room thing.



It's really quite something this combo. If I have any criticisms of (mainly my own work, probably not the drivers) the speaker, I still have a little boom at PR tune to work out around 38-40hz and the tweeters seem to lack a little air or brilliance right up in the top octave I have heard in other builds/speakers. Cymbals and hi-hats don't quite catch me like they do with the ATC tweeter in my main system. Its weird because there's nothing wrong with the measurement but I'm searching for it when listening. Room, cabinet, tweeter, amplifiers, my ears getting old/too much router on the weekend? Still early days and more tinkering to do yet.

I dropped the harsch crossover back to 1.8k (2k acoustic) to see how the tweeter goes. And so far its pretty good, however listening way off axis (like 90deg) there is a big audible hole at XO, so I know I still have crossover work to do. No doubt this will further improve on axis listening. Hard to think I could with what I'm hearing in my listening position. Shout out to the bliesma T34A tweeter, amazing distortion measurements and can take a beating.

Thinking about TL build now. Also need to calm down and focus on fixing up the house some;


End gush post; photos attached;
20200602_184050.jpg harsch 1.8xo purifi.jpg harsch 1.8xo purifi allspl.jpg bliesma t34a in baffle distortion.jpg
 
Congratulations mainframe99. It is a beautiful build.

A couple of questions:
1. How did you brace it in the end?
2. Is your Harsch XO in the cabinet?

Ed

Dont forget jmpsmash beat me to the build and gave me the encouragement. Credit where its due. I hope he/she's hearing what I'm hearing. Especially with that exotic BW tweeter.



Currently using minidsp for the xo. I think I'm retiring the soldering iron for my future speaker builds unless sold or gifted on. Passive is easy for the layman, but the future is digital imo.



Bracing was via a long solid 3/4 sheet running full width top to bottom in the center, positioned on a 20ish degree angle closer to the PRs at the base and tweeter at the top, with a large round-overed window about 1.5-2x the size of the woofer SD cut into it behind the tweeter to allow air movement but retain bracing all the way to the top panel. I used various organic underlays, foams, fill and sound deadening materials throughout the box until I was happy with the sound. I measured minimal mid leakage through the PRs - a small rise around 500hz that I'm investigating. Inside the cabinets the woofer cannot directly "see" the PRs. My thinking was any mid from the back of the woofer needed to have a hard time getting there, whilst keeping box volume at a maximum for better tuning. I purchased some better washers this evening and added about 28g to each PR and it seems to have solved my 40hz boom. I'm really liking the bass with the PR's, the distortion measurements dont show it but I can really hear bass guitars and kick drums a LOT clearer than with reflex and even sealed speakers I've had. I dare say I prefer bass guitar with these than my ATC 40's :eek:
 
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Fantastic build there Mainframe! Looks beautifully constructed. That Bliesema has got to be the Cat’s Meow.

849399d1591082400-exploring-purifi-woofer-speaker-builds-harsch-1-8xo-purifi-allspl-jpg


I really like the crossover curve and the slight tilt down and to the right. Superb.

That Harsch XO is perfectly executed. 55deg bump in phase and flat everywhere else.

Your step response must look magnificent. Can you share that?

Congrats! :cheers:

X
 
Looks great! The FR slope really can't get better than that.

How much sound absorption did you end up with? My box still have some resonance. I ordered some absorption material but the shipping is held up probably due to the protests!

The B&W tweeter isn't anything exotic. My friend had it for nearly 20 yrs and it was dinged up. He recently swapped them out so I took them in to play with. It is supposed to be mounted on it's own housing with a tube to dissipate the backwave. I just kinda 3d printed a faceplate and it measures horribly. I ordered a pair of Transducer Labs ceramic instead and I have another CSS tweeter I can try also. The Bliesma is sold out everywhere but damn the matching looks incredible from your measurement.
 
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Warning: Gush post forthcoming.


I've finished my PR build and much prefer it to the bass reflex box I had before. I ended up around 23L internal with everything installed. It's hard to think that I could get better sound from a bookshelf speaker. Best bookshelf speaker I've heard was the SCM19 from ATC, and the most expensive I've heard was the Dynaudio Contour 20. I've gone way past them with this build I think, but I don't have them here side by side so the usual grain of salt applies. There is also a lot of self satisfaction with DIY, but at this point I will happily say this speaker will be with me for a long long time. I have been listening almost non stop since I completed them and just don't want to stop. The old digging through the record collection again trick. Everything from 35hz to 20khz is there and perfect. It sounds like I have near-field studio monitors but I'm mid to far field and there's that perfect touch of warmth in the bottom end that makes you lean back and enjoy for hours. Studio monitors tend to have you on the edge of your seat and that gets tiring. I am simply amazed by these drivers, and I can play any volume I like up to almost party levels with no audible distortion. If I'm honest I cant even hear distortion before a woofer bottoms out. These are the first bookshelves where the sound stage actually extends out beyond the edges of the speakers, and I mean I keep looking to the left and right in disbelief. I've read about it numerous times but have never experienced it quite like this, so for ages I was trying to figure out what was wrong as I was certain the phase was reversed somewhere or something. The main system has never done it. Probably a room thing.



It's really quite something this combo. If I have any criticisms of (mainly my own work, probably not the drivers) the speaker, I still have a little boom at PR tune to work out around 38-40hz and the tweeters seem to lack a little air or brilliance right up in the top octave I have heard in other builds/speakers. Cymbals and hi-hats don't quite catch me like they do with the ATC tweeter in my main system. Its weird because there's nothing wrong with the measurement but I'm searching for it when listening. Room, cabinet, tweeter, amplifiers, my ears getting old/too much router on the weekend? Still early days and more tinkering to do yet.

I dropped the harsch crossover back to 1.8k (2k acoustic) to see how the tweeter goes. And so far its pretty good, however listening way off axis (like 90deg) there is a big audible hole at XO, so I know I still have crossover work to do. No doubt this will further improve on axis listening. Hard to think I could with what I'm hearing in my listening position. Shout out to the bliesma T34A tweeter, amazing distortion measurements and can take a beating.

Thinking about TL build now. Also need to calm down and focus on fixing up the house some;


End gush post; photos attached;
View attachment 849397 View attachment 849398 View attachment 849399 View attachment 849400
Well done M99 they are looking good and the measures are impressive for a "two way". In the old days we use to say lesser speakers had a "one note bass". The Purifi seems to make every other speaker sound as if it has a "one note bass". Well done:)
 
Here's the step response measured at 500mm and some veeery rough polar measurements at 0,30,60 and 90 degrees horizontal. I still feel like the bliesma tweeter doesn't quite hit the highest octave like smaller dome or other tweeters do as mentioned previously, and if I could I would like to get vocals just a little more forward can anyone help me with that? - do I need more 1-2khz or is it likely my floor and ceiling bounce are the problem as my cross is at 1800 and I need to take more measurements...?


harsch 1.8xo step.jpg harsch 1.8xo polars uncalibrated.jpg
 
Scale! Tweeter is 5dB down, but directivity is really fantastic without waveguide.

I´d liek to see nearfield response of Purifi and passives. The woofer can easily take huge boost, if tuning is low enough for that.

You can see this post in this thread:

https://www.diyaudio.com/forums/mul...rifi-woofer-speaker-builds-6.html#post6221502

As for huge boost. Depends on the size of the room. I have a 20x20x9ft room and mostly it is ok, but for anything with a loud drum it is right at the edge of bottoming out. I have heard a few bottom outs while listening over the weekend. For larger room, perhaps 2x on each side it will fill the room as well as keep distortion lower.
 
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