2 way stand mount build

[Janus77]

The Mini DSP HD + 4 x 15w mono amp rig is great, plenty of power and easy to adjust.

[kiwilistener]

They sound really mellow, my kind of speaker.

Who is the artist and the track, I would love to listen to the whole track.

[Janus77]

16 hours ago, kiwilistener said:

They sound really mellow, my kind of speaker.

Who is the artist and the track, I would love to listen to the whole track.

its a Chet Faker recording on YouTube.  

[Janus77]

New job has resulted in far less time for speaker building unfortunately.

I did manage a day in the workshop yesterday though.

I need to set up a jig to get the veneer cut back to the same diameter as the driver rebates, have a shank side bearing'd flush trim bit on the way arriving Monday.

Once done will sand the baffles lightly, then scandanavian oil finish on them, then 1 more coat of Duratex on the sides, top and bottom.

 

 

 

[Janus77]

Note to self, ALWAYS veneer before cutting driver rebates.  What a massive PITA.

Have ordered one of these, i have a piece of wood to use as a template for the shank bearing flush trim bit, hopefully my router fits the router guide: https://www.amazon.com.au/dp/B07K3LWZ12?psc=1&ref=ppx_yo2ov_dt_b_product_details

 

Managed to trim the veneer on the woofer rebate as it was deep enough that i could remove the screw from the bearing to get it to cut.   Still need to sand around it (rough edge), looks nice though.  Tweeter veneer not trimmed back so can't sit flush:

 

[Janus77]

Progress.  

[Janus77]

Danish oil applied to 1 rear baffle. 

[Antipodean Brad]

On 16/12/2022 at 5:46 AM, Janus77 said:

Danish oil applied to 1 rear baffle. 

 

I can't tell if your speakers are two feet or four feet.

 

But they do look very nice.  I am looking forward to the finished product.

[Janus77]

I nearly missed the joke

[Janus77]

Pleased with the look.  Now for crossovers.  

[ICUToo]

2 hours ago, Janus77 said:

Pleased with the look.  Now for crossovers.  

Looks great - the Duratex / veneer border is lovely.

[Janus77]

Hooked up to the dsp 4x15w mono amp tuning rig.  Sounding nice at 1630hz LR2 crossover.  
Hoping to get these finished in the next few weeks.  

[Janus77]

Ok, on to crossover design.

 

First challenge, i've taken free air measurements of the drivers with Dats3, i have 6.33ohms Re on the tweeter and 6.19 on the woofer.  When i plug these values into a crossover calculator for a LR2 crossover and select the crossover point at 1630hz, i get a significant variance in Xsim using those inductor  and capcitor values.  Xsim is giving me a crossover frequency over 2,600hz.  In Xsim i've uploaded the .FRD response files measured in REW and the .ZMA impedance files from Dats3.  

 

Any thoughts?

 

Edited January 15, 2023 by Janus77

[RoHo]

A wonderful example of the limitations of “off the shelf” crossovers.  The calc assumes a constant impedance and flat frequency response with the output being a standard defined roll-off eg LR2.  A real driver usually has a lumpy impedance and a FR that rolls off.  So the results will be different.  The object is to manipulate that roll-off to be the desired LR2 or whatever the chosen target is.  So you will need different component values.

[Janus77]

Thoughts, comments? 

 

I'm not going to try and fix what is probably some cabinet diffraction around 6-9khz (it disappears off axis).  Have been running them with my mini dsp rig, they sound good with a crossover at 2khz, though a touch shouty, so i've backed off the response around 9-1200 and also 3-4.5khz.

 

is the phase response close enough? 

 

Edited January 19, 2023 by Janus77

[davewantsmoore]

On 19/1/2023 at 10:14 PM, Janus77 said:

is the phase response close enough? 

I've seen a lot worse in "my first speaker"... but no, not really.

 

An octave above the crossover the drivers are roughly 180 degrees out of phase.    You need to adjust the rate of rolloff of one or both drivers, so that the phase of both drivers rotates at the same rate.   Then when you align the phase at the crossover point, it will stay in alignment for an octave above and below the crossover point.

[Grizaudio]

On 12/08/2022 at 7:53 AM, Janus77 said:

its a Chet Faker recording on YouTube.  

Shazam says "No Diggity Live performance". 

[SonJay]

They look great! Very keen to see how you go with finalizing the crossover.

[Janus77]

On 25/1/2023 at 2:06 PM, davewantsmoore said:

I've seen a lot worse in "my first speaker"... but no, not really.

 

An octave above the crossover the drivers are roughly 180 degrees out of phase.    You need to adjust the rate of rolloff of one or both drivers, so that the phase of both drivers rotates at the same rate.   Then when you align the phase at the crossover point, it will stay in alignment for an octave above and below the crossover point.

 

Changed to a 2nd order woofer, 3rd order tweeter phase matching is better, getting the phase rotation to match is still challenging though.   The bump in response on the *tweeter (thanks Dave) around 2000hz makes the phase wonky, otherwise they're well matched up to the crossover point, not great after..  

 

I need to get some ground plane measurements for the low end..

 

Edited February 11, 2023 by Janus77

[davewantsmoore]

3 hours ago, Janus77 said:

 The bump in response on the woofer around 2300-3600

Do you mean the tweeter?

[Janus77]

Work has been leaving me little free time.  
managed to demo the crossover on one speaker.  Hopefully put the 2nd together for some stereo listening tomorrow.  
 

 

[Janus77]

Between children, wife and work i've had little time for speaker building recently.

However the kids going to a friend's for a playdate on the weekend gave me some spare hours, and so i've progressed the build.  Am quite close to finishing now, just need to do some final coats of Danish oil, cure and sand the baffles, then a coat or two more of Duratex.  Should have them finished in the next few days.

 

Will post up some pics once completed.