DCAudioDIY.com

Curious what projects are going on!

Since I'm back at work after my second knee replacement (yes, it still hurts), I've embarked on a whole slew of upgrades.

Bruce Normann, G_d bless him, told me about the GR Research YouTube channel. I spent many, many hours watching those informative videos and realizing so many mistakes I've made. Thanks, Bruce!

I discovered that just because I'm tri-amping, doesn't mean that there are no passive elements between the amps and speakers, except the subs. The ribbon tweeters still need large value blocking caps since DCR is 0.02 ohms and even a little bass energy would fry them. The ribbons also need notch filters. The midbass speakers need baffle step compensation, and also seem to work better with Zobel networks in place. also, figured out experimentally that wiring the 16 ohm woofers in series and connecting to the 32 ohm amp output didn't sound nearly as good as the parallel connection. I'd hoped for it to be a more efficient method of power transmission since it was using all of the output transformers' secondary windings.

So, these "crossover" elements will be mounted inside the cabinets, the woofers wired in parallel internally, the cabinets stuffed a little less, the foam removed from the front of the cabinets, since the diffraction from the edges of it were very obvious and annoying (the opposite of what I thought might happen and the whole reason I put it there). Also, the tweeters will be recessed about 1/2" into the cabinets. They have been mounted on an 1/8" plate on the surface of the cabinets. This because I originally used a different tweeter with a larger cutout. Gonna make inserts and "flush" the face of the tweeters. Hopefully a bit better time alignment.

David M. graciously gave me a pair of JCAT Femto cards, USB and Ethernet in return for my assistance with his isolation transformer installation. To use them, I need to construct a small and quiet 5V supply for the USB card and the power side of the USB "Y" cable. The Ethernet card can connect to the same power supply connection that the SoTM USB card uses now, just adjusted to 5 volts output also. The HDPLEX power supply has an unused 12 volt 10 amp output. The plan is to regulate this down to 5 volts with a reasonably quiet regulator, then filter it with two LC sections using 1000uF Silmic caps and 1.5mH 100mohm inductors. Of course tantalum caps at the regulator pins and a PP film cap at the final output.

The Nelson Pass DIY 6-24 crossover I'm using will get a passive high pass filter in the low pass section. This to roll off everything under 100Hz from the MTM speakers, leaving the rest to the subs (through the miniDSP). This will be switchable so that the MTM or any other connected speaker can be run full range. Also, I made a stupid choice of attenuators for both high and pow pass filters. Useless. Gonna replace those with ~6 position rotary switches configured in series style to allow ~1.5dB steps down from full volume. Also, need to remove a pair of V-Caps in favor of Miflex caps. The sound of these was ......unfortunate. Clear, but fatiguing.

The preamp I'm using is a very old build, a mu follower 6SN7 with a ladder-style stepped attenuator. Not terrible, but I can do better. So that already stuffed Aikido octal board that's been sitting for 10 years will finally get some use. I've got shunt regs and constant current sources and an already built power supply. Just need to box it up, use the Penny and Giles pots, and add input and output buffers. The plan is for buffered and unbuffered inputs and outputs, depending on source capability and load demands. I've got no intention of buying and installing 10uF caps at the output to drive loads under 10k ohms. The servo buffers work very well.

Then it's time to finish those bass amps and line arrays!

When will I ever get to those OTL amps?

Oh yeah, vinyl is due for some attention as well. Not to mention reel-to-reel.

So, what are you all up to?

Slick

One recent project is the distributed subs I built to fill in the huge 40 Hz suck out I had at the prime listening position in my audio room. The article I wrote in in this month's issue of audioXpress.

Nice!

New room looks great!

I finished building the SMJ Ardent D's last year in December, and I plan on starting to build a new SMJ center channel this fall. Eventually I want to get into some amp building.

The SMJ Ardent D's are the towers. The MT's got moved up to the den after this photo.

That is FANTASTIC looking woodwork!!!

Very cool! As nice looking as anything I saw at the Speaker Design Competition last month.

Someone is too modest.....so I'll post it.
Build Log
https://www.htguide.com/forum/forum/primetime-a-v/mission-possible-diy/build-stories/43343-smj-audio-ttc-style-ardent-d-build/page7

A work in progress:

Drivers are:

Tweeter - Dayton PHT1-6 Planar Horn Tweeter 6 Ohm

Midrange - Horn: B&C ME75
Driver: Radian 850PB-8/16

Bass - B&C 10MBX64

I would crossover at 100 Hz to a subwoofer. The system will have a DSP crossover I don't know which one yet. For amplifiers I am currently debating whether to use Ice Power boards for an all digital amp or get an Emotiva A6 (6 channel) which is classic AB pure analog with a linear power supply. The box on the right is the back volume for the bass driver. It is supposedly tuned to keep the bass reasonably flat tp 100 Hz. I will use my boat anchor (Emotiva XPR2 which I had gotten for my previous Carver speakers) to drive the subwoofers.

That is where I did to my build log of the Ardent D's. I worked with Steve Manning who owns SMJ for the speaker kits. After seeing how much time I could save by having Steve do all the wood working and I just do the finishing it was sold on the idea. Plus my wood working skills are not near as good as his!

The center channel is the next build that I have been wanting to do. Steve moved though and getting his shop back up has taken time with all the delays Covid caused. After the CC I want to get some new surrounds made to replace the SVS I have in the rear and get another pair made for side channels.

The room that I'm using for the theater/music listening has been a journey! I gutted the room starting in 2017, re-insulated, wired, dry walled, paint, and put in the ceiling. Then I got some carpet installed. I want to get a door installed next and do some more room measurements to get wall treatments figured out.

It's the sound/video adventure continues

Well, after receiving the new-to-me Nestrovic 5AS MkV RE speakers from Charlie a few weeks ago, my main DIY goal it to make sure all my amps are capable of driving them. I just received a pair of Heyboer Peerless S-265-Q output transformers this week, so working on converting the stereo EL34 Williamson amp I built a year ago (using UTC LS-55 OTs) to a Musicians Amplifier (807/KT66 UL), increasing output from 15W to just under 30W. Next project after that is my GM70 SET amp, which needs a driver upgrade for sufficient voltage swing (and current output) ensure A2 operation, thinking about a 6P5 into parallelled sections of a 5687, IT coupled to the GM70 grid. I should be able to get at least 30W with this setup). Other than that, the project pool is kind of shallow for now...more time for listening.