DIY two way active mayhem

[zog]

Hi,

 

I thought I'd post an overview of my loungeroom system now its approaching completeness in it's current form. Portions of this have been documented in the DIY section here and other sites and forums, but here it is as a whole system.

 

The overall plan for this system has been a simple active two way with horn/waveguide HF section, taking on board ideas from both the "Econowave" project and a nod towards those older big American speakers with horns & 15" bass drivers, like Klipsch, Altec, etc. But using a modern active DSP crossover, and mostly digital sources.

 

I've also just been switching amps and other parts in and out for fun, buying random DIY boards from the internet if I read an interesting thread, etc. I tried two other waveguides before settling on the current one.

 

It's not particularly high end, there are a few rough edges I need to refine, but it is probably unique and I like the sound.

 

HF section.

• 1.4" compression driver and waveguide, FaitalPro HF144 with 18Sound XT1464. I've got this just sitting on the woofer enclosure, for ease of trying different waveguides. The compression driver is propped on a small wooden box that holds the LPAD resistors (7dB attenuation on the HF) and protection capacitor.
• JLH 1969 8watt Class A stereo amplifer. These are usually 10W but I am running it at a lower voltage. This is a very simple build from a Chinese kit, using a switched mode power supply, and the enclosure is re-cycled from an old Korean amp. This is the "winter" amp, during summer I was most recently using a $6 15W TDA7297 chipamp.

 

Crossover frequency is currently 600Hz (or was it 550?).

 

LF Section.

• 15" LorantzC390X B1 Australian made bass drivers. I was checking out all sorts of US, UK, Italian and Spanish drivers.. but ended up with one made in Dandenong. These are in 140 litre pine plywood bass reflex enclosures. Drivers second hand from ebay.
•  ConnexElectronics TA3020 V3c "Tripath" Class T amp module. In a very industrial steel PSU case as enclosure, powered with a 500VA 35v-0-35v transformer, the highest voltage this can run at without needing a cooling fan. Approximately 110W/channel. I've attached a bit of stained pine to the front to cover most of the industrial steel ugliness.

Crossover & Sources.

• MiniDSP 2x4 crossover plus miniDIGI daughterboard, with OPA2134 opamps on the output as the miniDSP is too quiet to drive most of the amplifiers I try. This is all mounted in a rough and ready pine enclosure, with a "fine" (miniDSP software) volume control and a "master" (ganged stepped attenuator for the opamp stage) volume control.  There is an analogue "guest" input on the front panel for visitors to plug in their DJ mixers/laptops/etc into, but the main sources are all optical SP/DIF. Powered by a Jaycar kit linear power supply.
• Input selection: optical sources selected with a mechanical optical 4 way switch, an AC-1597 from Jaycar.
• Main source: a "home theatre" PC running Xubuntu Linux 14.04, with an Intel i3-2100t CPU on an Intel motherboard, Antec ISK-300 case, and an SSD. The problematic Antec PSU replaced with a PicoPSU. I mostly play .flac files streamed via NFS using the Linux "clementine" media player app. Youtube and Mplayer get a lot of use as well. The audio is just using the stock optical out on the Intel motherboard. This PC is about 4 years old but works just fine, and runs extremely quiet despite it's two fans.
• TV - Sony Bravia KDL40 EX500 40" LCD TV. This mostly gets used as a monitor for the PC, but the optical out is hooked up for the rare TV session.
• DVD/CD player. An old DSE "Digitor" DVD player. Definitely not a high grade unit, not often used but it does appear to handle a lot of formats so kept around.

Other bits.

• Interconnects are mostly DIY from Altronics and Jaycar parts.
• Wireless keyboard and mouse.
• Speaker cables and optical cables from Selby Acoustic.
• ALDI master/slave powerboard - this is very handy, it uses the TV as a master device and turns off the amps & miniDSP when the TV goes into full standby mode, about 15 minutes after the TV is turned off with the remote. Not such a big deal with the miniDSP and Class T amp, but great once Class A amplification was added to the mix. So the whole system (except the PC) can be powered on/off from the TV remote.

I've intentionally assembled all gear with no panel lights to cause distractions, the lights on lots of gear were annoying my wife.

 

Things still to do:

I still have a lot of work to do refining the crossover, I've done some initial work with The Active Crossover Designer with good results, but I really need to dig much deeper here. I've had a lot of help and advice from the guys in the SNA DIY section, thanks!

I'm not completely happy with the finish on the speaker enclosures. The third coat of stain/varnish was applied at night and I didn't see the drips and patchy bits. One day I'll haul them out for another sand and coat. But its OK.

The digital source is pretty much "out of the box" Linux with Pulseaudio. Apart from verifying I'm getting unmodified 16bit/44100 for CD quality flac files, I haven't explored too far here. The miniDIGI does on the fly samplerate conversion and reclocking to 48khz so maybe it doesn't matter.

Edited June 6, 2015 by zog

[zog]

Bedroom System, more DIY mayhem:

 

econowave speakers, TPA3118 amp, hifiberry & raspberry PI

 

 

These are my old "classic" Econowave speakers, with crossover boards from ZilchLabs, MDF cabinets painted in terracotta pavement paint. As they have been located near high traffic parts of the room so the bed is in the "sweet spot" I've made them look even more like party speakers with addition of metal speaker grilles over the woofers. The functional durable finish is not pretty but it is handy as due to their location they end up with stuff stacked on them.

 

These are about 94dB sensitive, and use a Selenium d220ti Compression driver and Eminence Delta 12LFA woofer.

 

They have external passive crossovers, hooked up to a "Wiener" TPA3118 20W Class D amp in a stained pine enclosure, with a stepped attenuator.

This in turn is connected to a Hifiberry DAC with a Raspberry Pi in a simple Jiffy box enclosure.

 

The Raspberry Pi runs "mpd" music player software, which I control with my android tablet, or phone, as a remote control.

I'm using a TPlink "ethernet over power" adapter to talk to the server where the flac files live.

Again, no LED or lamps in sight, and this setup runs dead quiet.

 

passive crossovers being assembled:

 

[Tony ray]

Nicely done Zog, I do love DIY Audio setups

[murrmax]

how do they compare to your earlier econowave model? 

[zog]

how do they compare to your earlier econowave model? 

 

Definitely better, and more bass! And clearer.

 

It's a bit hard to say more, as the newer speakers have undergone constant modification and refinement, both in parts (3 waveguides!) enclosures and crossover changes since I trundled the red econowaves out of the loungeroom, and where they are now I can't do much of a direct comparison.

 

Waveguides tried:

[zog]

Summer time has definitely hit, time to put the JLH1969 Class A HF amp in storage, now replaced by a "$6" TDA7297 chipamp (approx 15W).

I also hit some issues with intermittent noise in my TA3020 amp which I haven't had time to troubleshoot yet, so I've got my IRS2092 Class D amp deployed. Approx 120W ? using L15D ebay modules and an SMPS,  in a re-purposed, recycled enclosure.

 

 

Some slight miniDSP adjustments to take into account the different amp. gains.

 

 

[zog]

Some minor updates to the system recently:

• For about the last year I've been running with the IRS2092 Class D amp for low frequencies and the JLH1969 Class A amp for high frequencies.. the IRS2092 is a bit noisy so I wouldn't mind upgrading to a quieter Class D amp, but it's not a major issue. When I get time I might check out the TPA3255 amp boards that are starting to appear.
• Changed the passive / mechanical toslink optical switch for an active one with remote control, the movement due to the effort needed to click the mechanical switch causing cable hassles. New unit is a basic low cost ebay unit.
• Upgraded the main "media / youtube" PC with a new motherboard and new Kaby Lake i3-7100T CPU. This is running Xubuntu Linux 17.04 with bleeding edge Intel drivers ( https://01.org/linuxgraphics/downloads/intel-graphics-update-tool-linux-os-v2.0.5)
• Also I've been playing around with some "supertweeters" using a Selenium/JBL ST200 connected with a simple capacitor crossover piggybacked on the HF.  Previously I was trying to get more HF by just boosting above 10-12Khz with the miniDSP, now the software boost has been backed off to let the ST200 take over. Still a "temporary" setup though I think it sounds a bit better.

Edited September 2, 2017 by zog

[highcut28]

Hi Zog
I found this thread when i searched the forum for TPA3255 amp.
Did you check out this  Class D amp?
I am considering using it to handle the Hi Pass of a semi active system I am building.
 

[zog]

On 24/07/2019 at 7:02 PM, highcut28 said:

Hi Zog
I found this thread when i searched the forum for TPA3255 amp.
Did you check out this  Class D amp?
I am considering using it to handle the Hi Pass of a semi active system I am building.
 

Hi,

Although I have been quiet on the DIY audio front one recent thing I did do was assemble a TPA3255 amp module, it's great! I'm using it for my LF amp, driven with a 350W 48V Meanwell SMPS.. So I guesstimate this is about 140W per channel, though the module is capable of more. I am using the TI Evaluation module, which is a well built board with a lot of flexibility.

 

I'm still using the 15W TDA7297 for HF amp, I think a TPA3255 at full power is overkill of the HF amp of an active system (at home volumes).

 

 

[zog]

The TPA3255 module I'm using is this one: http://www.ti.com/tool/tpa3255evm

 

Two minor fine tuning I would do now if were to re-make would be to use the following parts instead, these are better than what were available at the time, but just incremental improvements to the same idea:

• HF146 instead of HF144 - more even frequency response, but otherwise the same: https://faitalpro.com/en/products/HF_Drivers/product_details/index.php?id=502020173
• miniDSP 2x4HD - higher output levels than the 2x4 (older model) so I wouldn't need the preamps, and optical in and remote control: https://www.minidsp.com/products/minidsp-in-a-box/minidsp-2x4-hd

[highcut28]

Great stuff Zog
My set up is  semiactive driven modified Yamaha NS1000 
 pre amp to 500Hz analogue eXO.
High Pass to power amp to simple 2 way passive XO that feeds Yam tweeter and midrange, both 8ohm.
Low Pass  direct to Scanspeak woofers 4 ohm, power hungry.
All in new cabs 
At the moment using power amp section of sansui AU111 to handle High Pass ( abt 45 wpc) but its making crackly noises so i am looking at TPA 3255 to take over but TPA3166 would prob be fine.
Now using a Nak PA7 to handle the Low Pass, maybe TPA 3255 could replace this.
I am looking forward to receiving a TPA3255 amp ll made up, from China. I will need a PSU. 

Edited July 26, 2019 by highcut28
add

[zog]

On 26/07/2019 at 11:51 AM, highcut28 said:

Now using a Nak PA7 to handle the Low Pass, maybe TPA 3255 could replace this.
I am looking forward to receiving a TPA3255 amp ll made up, from China. I will need a PSU. 

 

A TPA3255 would certainly use less power!

Meanwell PSU seem to be the "easy choice" for most people doing straighforward builds with this amp.. no doubt you have already seen, but there is a fair bit of discussion about PSU selection for this amp chip on the diyaudio.com forum.

Although I haven't used it, the TPA3255 is part of a family of chips of differing power levels but the same design - there is also the TPA3250 (70W) and some others..

 

[zog]

A minor update to this system, replaced the miniDSP 2x4 with the more recent miniDSP 2x4 HD.  As this has higher output levels I don't need to use the 4 channel op-amp buffer I made to boost the levels. 
Generally a more fully featured and useful device than it's predecessor, but I noticed noisier (some hiss when closer to the wave-guides) than the older unit. The white noise is much less with the JLH1969 Class A amp than the TPA7297 chip amp (I alternate between the two for HF amps) due to the different gain structures, but not really bothering me as inaudible away from the speakers at the listening position. 

I got a small 12v linear power supply to drive it as well - and taped over the annoying bright blue LED.