Monday, April 09, 2007

Get dedicated! And why computers are your friend.

I had a long weekend and decided to spend a little time installing a couple new electrical circuits in my house.

Being rusty with house wiring, I took it easy, and expected it to take me all morning, and maybe a little of my afternoon. Took me all day! Multiple trips to the electrical supply, a lot of drilling in masonry, and a chunk of change later, a filthy me had installed the new lines.

One feeds the computer on my porch, which is a recent addition. Was having to run an outlet strip from another circuit for that, not ideal. So it got a dedicated line for the case, monitor, router, and modem, one box with 2 duplexes, bye bye to junky power strips and bad layout!

The other is a more complex beastie, feeding my 'big rig' (which I've been stuck with having on a pretty poor line prior to this). The 20A circuit feeds a pony box, which has a leadout consisting of five conductors, a ground and 2 pairs of L/N, in a twisted quad arrangement. This is all sheathed in PET braid for protection, and run into the music room, where it feeds a 2 duplex outdoor style box, with each pair feeding a different outlet (emulates 2 dedicated lines, to some extent) but a common ground.

There is a nice improvement in overall system performance, leading to a blacker background and better resolution.

Now: Why computers are your friend.

The above mentioned porch computer has a couple purposes, but one is the most important. It is my music server. Also functions as a web browser and other such pedestrian tasks, but its important function is ripping, encoding, storing and serving .flac files (lossless compression) through a Roku Soundbridge. The M500 is the baby of the roku line, now discontinued.... it also was available quite affordably, and doesn't do the hellacious upsample to 48kHz that it's big brothers do. This, fed from the network (primarily the linux file server discussed above) is giving me access to a flac-originated bitstream pcm, which goes into a digital eq and dac. I use cdparanoia for the rips, which is the linux equivalent of Exact Audio Copy.

Short version, it's awesome, the accessibility and speed of loading different music, and jukebox features, make it all lovely. And the sound is quite good too!

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Monday, February 12, 2007

Wow, that looks quite ridiculous eh? The selector switch and it's knob are both bigger than the transformers! This is a basic concept- a potentiometer (10k log, from PEC) on the secondary of a 10k:10k transformer. Input drives the primary, through the selector switch, which also switches grounds. The selector is a huge ceramic silver plated job from russian surplus.

Looks quite insane doesn't it? Well, don't bust my chops too much- it's well made, but fairly crammed in the chassis (which had previously been used for another project).

The idea was brought back to my mind by the discussion of the "Ingot" on the Magnequest forum at Audio Asylum. I'd previously used the topology (now that I think of it) as a volume control stage for a dac.

Fun eh? We'll see how it sounds!

Tuesday, January 30, 2007

Isolator completed. 3 Hardwired output cords (quickie types), hardwired input. Not a lot more to say here, lot of found parts and scratch. I've used such devices before to good effect. A diversionary mockup to distract me from future projects.

I may have a disease on my hands.... can't stop building junk... not even time to post most of it here.

Monday, January 29, 2007

Latest fiddlings

The innards: EI trafos with their secondaries connected to each other, in pairs. Common connection to the mains on the primaries of one group of transformers (3), the primaries of their correlated transformer are connected to the load (power inlet for DAC, CDP, ETC). It's a way to do an isolation transformer (with it's many advantages) with found transformers.

Don't know if they'll be good for more than 35W a pair. I'll toss some small caps across the secondaries for additional HF filtering. The output wiring and those caps are still pending.

The base. You can see that I used U-channel for the transformer mountings. Cut them by eye with a hacksaw, and drilled the holes by hand. All hardware is stainless, with nylon insert locking nuts. Nice and solid, despite the lightweight box (1/4" ply winebox). The cables will be hardwired, the quick and dirty power inley cable is shown. 3 leadouts with IEC connectors will be used to power several devices. I'm hoping it'll drive my DVD/SACD/CDP, which draws 43W according to spec.... might be too much. We'll see. Certainly the dac, linestage, and digital EQ effectively, so it won't go to waste if it's too small for the player.

What else.... fiddling with digital EQ in the big rig, installed surround channels in the bedroom rig. What's next, still pending is the preamp: octals, with phonostage. Will be using a chassis from Also, the time has come for us to start playing with driver modification. After that's up and running, we're probably going to have a little fun with a small open baffle, with a high density driver compliment- 4 8"s (peerless HDS), a high eff. midrange and tweeter.

I've been keeping hifi on it's toes for a goodly while now.

Thursday, January 04, 2007

A little fix me up

The big rig needed a little TLC. There's a circuit correction for the transcendant that was never done (is now), not to mention, swapped out the horrid heater diodes for the driver stage (1N4007, awful noisy nasties) for uF4007, a 25c drop-in much lower noise replacement.

Nice gain in smoothness and clarity, a little better transparency too. Don't know how much came from which, but I've always had impressive results replacing noisy diodes in the past. I also had to make a fix in the linestage (12AY7 based circuit, simple plate amp running at about 190V and 3mA.), the grounding on the attenuator (chinese 24 step stereo 100k ladder) had worked it's way loose, so it was intermittent, and jiggling around causing the loss of the shunt element..... drivers with 0.3mm xmax aren't meant to jump around! Good thing they weren't hooked up to a big class D amp, but rather the OTL.

Next Victim on the repair list: A finnicky LP12. Also have a passive preamp to rebuild for a customer, and my own big Phonostage/Preamp. After that, looking like open baffles, probably with 4 8"s ..... perhaps with a horn midrange! How strange! Still working out the details of the horn, probably a 400Hz or so round tractrix.

If anyone's reading this, comment so I know!

Wednesday, January 03, 2007

Some Miscellaneous ramblings and my office rig

The Dyanco Super 70, an Audio by Van Alstine rebuild of the classic kit amp (New driver stage, power supply). This is replacing a little Sonic Impact T-Amp, the $30 wonder amp. Well, this AVA piece is definitely a lot more powerful and has better mid and detail, but there seems to be a less airy top end. Wondering if I just need to let it get up to speed. It definitely doesn't suck.
Had to re-rectifier and rebias and replace a broken Silver Mica cap in this, but otherwise in decent shape. I bet a little TLC and I could get some real singing out of this.

Beneath it is a DIY build into an old Rotel CD player chassis (waste not, want not). Microprocessor controlled relay and resistor network, 4 source selection, 99 step 1dB volume control, balance, mute functions. Nice little box to stack under a power amp when you really need an integrated and not an active linestage. Basic Pioneer CD changer (a better dac would open things up, so may go to hard disc playback with a dac) And of course, these are driving the Galacticons (scroll down). Pretty darn good office system. And yes, the FR125s can bump a little bit, though ultimately still a 4.5"

In the bedroom rig, the Peerless HDS tweeters are singing nicely, I have the whole setup wired as a 2.5 way first order (midrange/woofer first order at 240Hz, cap coupled tweeter, no lowpass on the mid), and it's pretty rocking. The 15"s don't overpower the room, even run passively, which is lucky.

Working on a big preamp next, probably, octals w/phonostage. Got the parts, need the time. Anyone got a week to spare?

Monday, October 23, 2006

Baddy's upstairs rig

The upstairs rig

This is the upstairs rig, which is a pair of fullrangers in nice cabs from middle branch furniture (Marlboro, NY), with helper tweeters (still working out the kinks there, the new peerless HDS tweeters will be in service there soon enough). Down below, we have Eminence Magnum 15HO drivers in sealed cabs (courtesy of your badness)... but they're not running yet. They used to be in the big rig, until I got those neat-o rethms to play with. Mostly this rig is used for movies, via the Motorola DCP-500 receiver: a high power class D receiver with a linear power supply and tripath chips for $99 shipped via ebay.... I have several of them, what a deal! MSRP was $900, but they weren't marketable. (expensive all-in one/cable box). Sounds very good.

But that rig has a ways to go yet, lacking the refinement of the big rig (and the price tag). Speaking of the big rig...
Here we have the latest change, the heils on the rethms. A little doublesided tape has superceded the stands (how sad!) which are now on the porch of forgotten hifi. The expected improvement in wavefront integration was more than, well, expected... we're havin' some lovely stuff here boys and girls!

Keep tuned, and you'll know when I do.....
And oh yeah, adjusted the preamp a bit too....