SB Acoustics monitors build

[augerpro]

I've read cautions about using those bypass caps on the first woofer inductor without a resistor in series. It's a short to ground via the first parallel cap and can send an amp into oscillation. I usually throw an 8 ohm resistor in series with those bypass caps.

How does it sound? Tweeter better behaved? How much farther down is response at Fs of the tweeter?

[DeZZar]

I've read cautions about using those bypass caps on the first woofer inductor without a resistor in series. It's a short to ground via the first parallel cap and can send an amp into oscillation. I usually throw an 8 ohm resistor in series with those bypass caps.

Thanks - I wasn't aware of that. The resistor had little effect so I figured it could be left out. I'll put something back in.

How does it sound? Tweeter better behaved? How much farther down is response at Fs of the tweeter?

Still some more listening to do. I've only had one speaker running so far but have found enough crossover parts to get the second one up and running so I'll be doing that today and get some more listening happening tonight.

I would say there is no longer that sort of extra treble sticking around which I'm sure was due to the flare. Otherwise all the measurements say everything is behaved now - the tweeter is well and truly down at Fs (600Hz) @ -70db.

I'm unfortunately in a pretty noisy area on a main road so I don't really trust the distortion measurements that much (distortion and noise floor are the same! and distortion basically follows the noise floor!!!) - but, absolute levels aside, they are not showing any significant spikes etc at crossover or down near tweeter FS (0.24% THD). Actually the region 500Hz through 2K is the cleanest of the distortion results with a rise to about to about 1% over crossover that stays consistent for tweeter range.

Tweeter by itself at these levels (~90db) is just on 1% from 3K and up (with crossover in play) (again, according to my noisy environment).

I would describe the sound at the moment as very slightly forward in the midrange - and I think I will increase the first inductor on the woofer from 1 to 1.1 when I order the final parts.

I'm being super critical here (as usual) and to be honest its already crossed that threshold of where you can stop listening to the speaker and start listening to music - and to me that's always the pivotal moment in custom design where you know its a success. From here you can sort end up in a song vs song tweaking never ending loop (an adjustment for one track, reduces how good another one sounds and so on).

Neighbor was super happy two iterations ago and I can tell he just wants them handed over now! lol

[rpb]

My experience is that auditioning one speaker vs two is that two will sound less forward than one.

[DeZZar]

And that is exactly what's happened. Lol. Have spent some time listening to both hooked up now and I would no longer describe them as forward!

[DeZZar]

Long listening session last night and to cut to the chase - I don't think we'll change anything! No need to move to 1.1 on that first coil. As rpb mentioned above, once combined into stereo image what seemed to be a slight forwardness has gone completely.

Covering everything from metal to rock to country to jazz to classical to pop to dance and trance.....I'm really happy with the performance from these and second guessing myself as to why I'm giving them away!!

To use a bunch of subjective language - they have a warm rich tone with substantial depth that seems to defy their size. I have to confess that I have never really been that interested in bookshelf sized speakers for the simple reason I never found that they produced enough bass or bass depth for my liking - and although still true to an extent, in my view - these have completely shifted my mindset! The bass performance is substantial - never fat, bloated, flabby or overwhelming - just solid, punchy and full - not something where only a given note here or there make you think "oh yeah there is a bit of bass there" - nope - from the outset - even the pluck of a guitar string has that deep harmonic underpinnings that give it a full real life sound.

Male voices, like Sully Erna's on the track 'Broken Road' come through with a full rich tone that you'd expect from much larger speakers. His loud, 'pingy', 'echoy' piano playing, often problematic on some speakers, is rendered in its true form without any lingering uncomfortable harmonics.

Metal is what it is, you can listen to it and understand that its a bright loud amalgam of distortion, shredding and cymbal bashing without thinking "good grief, please take me back to the string quartet". The tonal balance is there without thinking the woofer dropped out.

Stereo image is strong and precise. Michael Jacksons Stranger in Moscow renders out the beginning parts with a precise centre, left, right, centre of the punchy synth notes. His voice is clear and dead centre. The sort of mind tricks dead centre - stare at the left or right speaker and try and convince your brain the sound is coming from them - you cant do it.

Diana Krall's Temptation is fantastic - the opening riff combination of piano and double bass might as well be in the room - and her voice is present and right in front of you - the brushes on the drums, the person slapping the tambourine - every little detail is right there as good as I've ever heard this track.

I could go on but I'm starting to sound like I write for What Hi-Fi so I'll shut up.

This of course is all via a crappy interface to a cheap amp through a conglomeration of nuts bolts plugs and wires for the prototype crossover using the cheapest crossover parts available. So I cant wait to see where this lands once we have higher quality parts in the final assembly. It'll be time to hook up my Rega for one final listen before I say goodbye :'(

[a4eaudio]

Nicely done! There has been a decrease in build threads here as people don't post a lot of detail or migrate to other websites. Your threads have been great, please keep posting your builds and all of the details, they are great resources!

[DeZZar]

Thank you. I really appreciate the feedback - I know I learn something from every build so if I can share and someone else learns something too that's awesome! :D

[DeZZar]

One other thing I can share at this point is cost.....if you're ever wondering exactly what goes into building a set like this and the cost to do a one off custom build.....well here it is.

These are current Australian prices in AUD.

Some things in Aus are pretty expensive - others on par. A 2x US Pint of Titebond wood glue costs me $25 for comparison.

Description	Qty	Unit ($)	Total ($)
Boxes
1200x1200 Sheet of 12mm MDF	1	$ 40.00	$ 40.00
Tasmanian Oak (135x19x2400)	1	$ 50.00	$ 50.00
Fastening & Misc (glue, nails, screws)	1	$ 10.00	$ 10.00
Felt Padding	1	$ 10.00	$ 10.00
Acoustic Stuffing	1	$ 10.00	$ 10.00
2" Precision Port	2	$ 25.00	$ 50.00
Boxes sub total			$ 170.00
Finishing
Tasmanian Blackwood Veneer	2	$ 20.00	$ 40.00
Contact adhesive	0.3	$ 26.00	$ 7.80
Danish oil	0.25	$ 55.00	$ 13.75
Cabothane Clear Satin (300g)	1	$ 26.00	$ 26.00
Sandpaper & Misc	1	$ 10.00	$ 10.00
Finishing sub total			$ 97.55
Hardware
Speaker screw (allen key, cup head, M4)	16	$ 0.40	$ 6.40
Threaded Insert (M4)	16	$ 0.40	$ 6.40
Speaker Terminals (Gold plated, set of 2)	2	$ 16.00	$ 32.00
Soundlink OFC Cable (13AWG)	2	$ 3.00	$ 6.00
Hardware sub total			$ 50.80
Drivers
SB Acoustics SB29RDC Tweeter	2	$ 55.00	$ 110.00
SB Acoustics SB17NRX2C35-4 Woofer	2	$ 77.00	$ 154.00
Shipping	1	$ 15.00	$ 15.00
Drivers sub total			$ 279.00
Crossover
Capacitors
5.6uf Jantzen Standard Z-Cap	2	$ 9.00	$ 18.00
3.3uf Jantzen Standard Z-Cap	2	$ 6.50	$ 13.00
0.56uf Jantzen Cross-Cap	2	$ 2.60	$ 5.20
15uf Jantzen Cross-Cap	4	$ 13.50	$ 54.00
Inductors
Jantzen 1.0mh 0.30Ohm	2	$ 32.00	$ 64.00
Jantzen 0.39mh 0.167ohm	2	$ 13.50	$ 27.00
Jantzen 0.27mh 0.414ohm	2	$ 3.50	$ 7.00
Jantzen 0.56mh 0.36ohm	2	$ 8.50	$ 17.00
Jantzen 1.2mh 0.55ohm	2	$ 11.50	$ 23.00
Resistors
8.2Ohm 10W Superes Resistor	2	$ 5.00	$ 10.00
5.6Ohm 10W Superes Resistor	4	$ 5.00	$ 20.00
1.0Ohm 10W Superes Resistor	2	$ 5.00	$ 10.00
Mounting Boards	4	$ 5.00	$ 20.00
Misc Mounting Hardware, Solder, Heatshrink	1	$ 10.00	$ 10.00
Shipping	1	$ 15.00	$ 15.00
Crossover sub total			$ 313.20
Total Parts/Materials Cost			$ 910.55

Q: Is it cheap to make your own speakers?
A: No

Q: Could I make them cheaper than this?
A: Sure - either you can find all the parts cheaper or change the finish and hardware. Or both.

Q: Should the cost of drivers be my focus?
A: Not really - once you consider the overall build cost - you'll wonder why you bothered only spending 30 bucks on woofers when you could have upgraded significantly and still not ended up with the drivers being the greatest cost. In this case the drivers were only 30% of the total cost.

Q: Is it worth it?
A: Very subjective question. I believe you would need to spend a lot more on a commercial product to equal the quality in both construction and output.

Q: Is this what you would sell them for?
A: Hahaha....not even close - no labour or workshop costs included above. These would have to be about $1,800 to a paying customer otherwise its just not worth it. However, you have to consider that for the the cost of a laptop you have a set of hand made speakers made from top quality parts, that sound amazing and will last 20+ years without missing a beat. My neighbour will eventually be giving these to his new born daughter for her first speakers!

[djg]

So converting to US currency, quite reasonable for the finished product. Very nice results. I just want to see that blue tape gone.

I think most people wouldn't see the value in "homemade" speakers. Your level of finish might overcome that attitude.

[DeZZar]

I just want to see that blue tape gone.

Not a fan of the painters tape? :P....just holding off gluing the port in until the terminals at the back are bolted in!

I think most people wouldn't see the value in "homemade" speakers. Your level of finish might overcome that attitude.

Thank you, that's very kind feedback.

I think you are right though - the perception around "home made" is that they will look home made ("handy man", "DIY'). If I change the language to "hand made, bespoke, custom, artisan" it tends to conjure up a different perception. The sort of difference between offering something made "in a small workshop" vs "in my garage".

[rpb]

Total balance can change a lot, just by changing the room they are in, or the location in the room! I suggest trying them in the final location before finalizing the xo.

[DeZZar]

I hear you - problem is that "final" location is a bit of a challenge. They'll start out in his garage/barber studio which is the same as my garage - but this is a rented place and there is no real finality to where they will live. I'm going to try and make it so the lpad can be easily accessed just in case we need to further refine the tweeter level.

[dkalsi]

DeZZar - thank you again for taking the time to document your build. I agree with a4eaudio's comment above - there is now a shortage of such threads.

[Geoff Millar]

To add to others' comments, this is a great build log: you've given us the genesis of the project, rationale for driver and cabinet selection, measurements, testing, listening and working through the crossover, plus of course they look great. Costs were a good inclusion, too.

Apart from that, I learned a lot from your thread and peoples' input, such as the need to include a resistor when using the small 'tank' cap on the woofer inductor.

Thanks again

Geoff

[DeZZar]

Thanks all for the comments and feedback. I'm happy to share the process and my learnings and I'm really glad its valued.

I'll update again once final crossover parts arrive and I button these things up for delivery :D

[tktran]

In passive crossovers adjustable baffle step, as well as tweeter level is very helpful in getting it dialled in for the room/placement.

[davidroberts]

Very nice documentation for a very nice finished product. Take a now sir, you have earned it.

[DeZZar]

In passive crossovers adjustable baffle step, as well as tweeter level is very helpful in getting it dialled in for the room/placement.

Yeah curious as to how others might have implemented this before. I can imagine a dial type selector to switch between several resistors (or resistor combos) on the tweeter - but what about baffle step? You would sort of need several different crossovers to select between?

The owner of these will play music from his computer so its probably just easier in this case to add a little EQ.

Very nice documentation for a very nice finished product. Take a now sir, you have earned it.

Thank you :D

[Ugg10]

Yeah curious as to how others might have implemented this before. I can imagine a dial type selector to switch between several resistors (or resistor combos) on the tweeter - but what about baffle step? You would sort of need several different crossovers to select between?

The owner of these will play music from his computer so its probably just easier in this case to add a little EQ.

Thank you :D

Another thanks for documenting this build, much appreciated.

As for baffle step selection, may be worth having a look at Jim Holtz / Curt Campbell's Statement Monitor as this has a Near/Far wall crossover and a scheme to switch between the two.

http://www.speakerdesignworks.com/MonitorSwitchableNetwork.PNG

http://www.speakerdesignworks.com/Statements_Monitor_2.html

[DeZZar]

Crossover parts arrived today!

Laying them out on some blank PCB perf boards. Smallish boards - large crossover - so I'll use a few of these.

Tweeter layout...


Woofer layout...


And the final set...