Late to the party - AAM build in 2025

[Nezil]

I recently decided to set up a desk top rig for the days I get to work from home. I'd been away from the audio 'hobby' for some time, and there was some catching up on where things were at these days, and this forum has been super helpful with that.

My initial setup was:

• MacBook Pro + Apple Music as the source
• Aiyima A07 amp
• Klipsch RB41 II speakers

And I've since moved on from that to where I'm at now:

• MacBook Pro + Apple Music as the source
• SMSL RAW-MDA 1 DAC & HP Amp
• Topping PA5 II amp
• Klipsch RB41 II speakers
• Oppo PM3 Headphones
• ELAC S10.2 sub
• SourdSource applying EQ generated by REW

This doesn't sound bad, but the Klipsch RB41s aren't great, and the extensive discussion following Amir's review of the Affordable Accuracy Monitors is leading me down the path of building a pair for myself... with a few tweaks to the basic recipe.

This is a thread to share and discuss that project.

 

[Nezil]

Taking on this project in 2025 is much harder than it would have been in the 2010s - Pioneer is no longer making the base speakers so they're only available on the used market, and what I assume to be tariffs affecting the stock of the components needed to complete the project.

I was able to find a pair, or rather 3?!? of Pioneer SP-BS22-LR locally on Craigslist. The seller wanted $100 for 2, or $125 for 3, but when I got there it was obvious that the tweeters were blown in all three... fortunately I don't need the tweeters and so was able to get all three for next to nothing.

Digikey is the only supplier for the tweeters, and they're backordered. I did place an order with them, but the expected shipping date just keeps getting pushed back. I've ended up buying these for much more money from a seller on eBay.

Parts express had some of the other parts, but not the inductors, so I looked in to winding these myself. I found a useful YouTube video that showed a process for doing this, but the method shown there used a tool that had been machined from a solid piece of aluminium.... with tools that I don't own! I do however own a 3D printer, and so was able to recreate the design with that, and wound my first air core inductor:

This worked OK, but I messed up on the dimensions that I was going for, and I discovered that the tool I'd made was far too big. I re-designed it and this results in inductors that are similar in size to the ones specified by Dennis.

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Here are a couple of the finished inductors attached to the crossover board:

BTW, I can share the 3D printer files if these inductor making bobbins are of any use to anyone.

 

[Nezil]

While I'm waiting for the other parts to arrive, I decided to turn my attention to the cabinets. These weren't in perfect condition, but I had three, and only needed two, so I've decided to experiment with veneer. I'm having to spend more now in 2025 than anyone who built these a few years back, so I might as well try to make them look nicer than the $100 speakers that they started out as.

I've ordered a 2' x 8' sheet of paper backed walnut, and I've removed the vinyl cover from the cabinet with the most knocks and dings. I patched up all of the damage and while I was at it, I embedded small magnets in to the mounting holes for the cover... helpful because I damaged the rubber inserts when removing them! It should also make a much clearer look once the front is veneered.

After flush cutting the mounting stubs off the cover, I CA glued magnets in their place. I'm planning to put something soft on top of the magnets to stop them marring the veneer, but they might be fine as is because they're not rough and I plan to run the speakers with the covers off 90% of the time. Here is how they look so far:

 

[kemmler3D]

Looks like a great start! How did you calculate the dimensions for the inductor? Seems simple enough to build if you can print exactly the spooling ... thingy... you need, but I'd wonder about how sensitive the crossover performance is to tolerances on that.

 

[Nezil]

How did you calculate the dimensions for the inductor? Seems simple enough to build if you can print exactly the spooling ... thingy... you need, but I'd wonder about how sensitive the crossover performance is to tolerances on that.

The overall dimensions for the inductor that's specified are given on the Parts Express website. I knew the AWG of the wire used, and I knew the outer dimensions, so using that I could calculate the inner dimension for the bobbin.

I also checked and tuned the inductance with an inductance meter. The Windows app that calculates the number of turns etc., didn't get it quite right. I needed 0.5 mH and I got 0.74 mH the first time! taking off a few turns brought that back down though and I then had a target number of layers for the next ones that I made.

I'd like to say it's easy, but keeping the wire tight and neat really wasn't. I had to stop multiple times for each layer and push each loop nice and close to the next to get it to all lie flat. Not too difficult, but it made my hands ache!

 

[Nezil]

Finished assembling the crossovers today. I basically assembled a pair, leaving one spare that I'm going to start doing the veneer on once that arrives.

They sound incredible... bass response is extremely impressive for a 4" driver bookshelf! I have a sub now, but it's only needed for < 55 Hz.... EQ'd flat, these AAMs extend down to 55 Hz before rolling off!

I mentioned earlier that I'd ended up ordering the tweeters from an eBay seller for much more than Digikey because I had no idea when Digikey was going to ship and they kept pushing back the shipment... Well I got an email form Digikey to say that the 4 tweeters I'd ordered have now shipped, so I now have some extras.

It's worth noting that Digikey currently has 110 in stock @ $14.66 if anyone is interested in building a pair of these.

 

[Nezil]

Some pics of the completed crossovers:

 

[Nezil]

I received the walnut veneer and wood finish I'm planning to use last night, and I got right to it...

I'm starting with the spare speaker I have first, because I'm using the other two at my desk already. This one had a small amount of damage in the top corner which I repaired with some plastic wood. I used Titebond II Dark glue, applied with a foam paint roller.

In order to best hide the edges of the veneer, the order I chose was bottom, back, sides, top, front. Here are some photos of the process:

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I used a flush trim router bit to trim the edges where there was a clear 90 degree angle, and a sharp knife, changing blades often, for the more complex angles. The router makes this really easy, but it leaves an imperfect edge that is easily fixed by sanding.

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Cut outs and recesses in the front and back were done first with the same trim router bit, then a special bit with no bearing that's just about shallow enough for the recesses. Here is how it looked after all the panels were fitted, trimmed and sanded.

 

[Nezil]

I applied Rubio Monocoat Pure for the finish. It sets up over a week period, but you can touch it almost immediately. I'll reserve judgement until its fully cured, but they already look great (I'm biased of course)!

I put drivers in, but they're not connected. I still need to add the foam inside the cabinet, the port and the crossover. It's plain sailing now though... Except I have to do a second one. Something good to do over the Memorial day weekend I guess.

 

[ernperkins]

What did you use to remove the original vinyl covering?

 

[Nezil]

What did you use to remove the original vinyl covering?

My hands… Haha… It’s really easy, it just tears off.

I tried using a heat gun for the first one, but that actually made it worse because the vinyl stretches and tears. Without a heat gun it does remove a tiny bit of the top surface of the MDF, but I don’t think that’s an issue.