Power Tower

Well, today I "finished" building this power conditioning and distribution system for my stereo system, repurposing an old Mac Pro case donated by a friend.
Here are the features:
1. Main AC Latching Relay  (drops out and locks out on a power outage, manually reset)
2. GFCI
3. Z-Wave smart-switch (Alexa voice actuated power control)
4. RFI filtering
5. Servo Variac automatic mains voltage regulation (Input swing 85Vac to 170Vac, output front panel adjustable, maintains +/-1V of nominal setting)
6. Digital AC raw mains display
7. Digital regulated AC output display
8. Linear 5V 3A regulated DC power supply (for Raspberry Pi/Allo Boss DAC)
9. Sequenced power-up (2-stage) for the various stereo component groups
10. AC voltage ramp up (soft start) for tube amp.
11. Spike protection MOVs

Works a peach, what I find superbly impressive is the glaring sonic difference upgrading from a 5V 2.5A switch-mode power supply to a linear 5V 3A regulated power supply for my Raspberry Pi3 / Allo Boss DAC / 2TB music server.

These cases are really awesome when gutted and repurposed for projects.
A little neatening up to do with some 3D printed bezels around the front outlets, and that should happen tomorrow. Right now I'm just sitting back with a fine Bourbon and enjoying the music.

No photos of the guts?

I'm currently using a variac to adjust the power to my ST-120. I regularly get 124-127v at the outlet and the ST-120 does not lit it one bit.

It would be nice to have something to make that adjustment without my involvement.

dalemurray wrote:No photos of the guts?

I'm currently using a variac to adjust the power to my ST-120. I regularly get 124-127v at the outlet and the ST-120 does not lit it one bit.

It would be nice to have something to make that adjustment without my involvement.

The Servo Variac I'm using is this unit, it works very well. I replaced the internal trimpot with a panel mounted 10-turn 1K pot so I can easily set the output voltage, right at the front.

Thanks.
It would be nice to have something I do not need to monitor to know I'm only delivering 120v to the ST-120.

@CletusB:

Nice job on your power conditioning/distributing system! Gut shots would be appreciated.

The automatic voltage regulator is interesting, but it raises questions.

1. How quickly does it adjust output voltage when there is a change in line voltage?
2. What is the line voltage variation that causes it to auto-adjust (e.g. 1, 2, 5v)?
3. Does it adjust output higher for low line voltage? What happens if there is a short duration brown-out - does it drop output voltage quickly enough to protect the load?
4. I notice it has no AC chassis ground wire at the entrance to the chassis. Are you concerned about not having any grounds to your loads?

Thanks!

gktamps wrote:@CletusB:

Nice job on your power conditioning/distributing system! Gut shots would be appreciated.

The automatic voltage regulator is interesting, but it raises questions.

1.  How quickly does it adjust output voltage when there is a change in line voltage?  It's slow maybe 1.5sec, but fast enough to keep up with our variation due to loads on the grid from nearby factories.
2.  What is the line voltage variation that causes it to auto-adjust (e.g. 1, 2, 5v)? - ~2v
3.  Does it adjust output higher for low line voltage? -  Yes  What happens if there is a short duration brown-out - does it drop output voltage quickly enough to protect the load? - My latched relay will drop out clean
4.  I notice it has no AC chassis ground wire at the entrance to the chassis. Are you concerned about not having any grounds to your loads? I added a ground, GFCI, EMI Filter Etc.

Thanks!

This is where it's at:

dalemurray wrote:
It would be nice to have something I do not need to monitor to know I'm only delivering 120v to the ST-120.

Even today many power transformers are spec'd @ 115v.

Line voltage regulation is supposed to be ±5% in the US. 105% of 115 is 121.

A bucking transformer with a three way switch can provide Line, Line - x and Line - 2x by using a CT transformer for areas with less than stable power.

See Bucking (And Boosting) Transformers by Rod Elliott

This Google Image Search give plenty options from utility to HiFi pretty.

I'm located in the Caribbean (Trinidad) so I used what I could get my hands on locally for this project.  With our power company anything goes, got a plastics extrusion factory right opposite and other factories nearby. On the grid during the day it could be as low as 105V and at night when the factories are off-line as high as 128V. Not really fast changes or spikes, but rather inconsistent overall, right now for instance it's 118V at the outlet and my Servo Variac is holding nicely at the preset 115V)

Cletus’ Music System 2023
(Continually Evolving)

I never, ever get tired of listening to my system!

Speakers: DIY Altec A7 “Voice of the Theatre” fully braced  cabinets with additional Bullet Tweeter (a number of drivers expensive and cheap were tried with the enclosures [back then, used what I could find locally] until I found what showed promising results on the measurements and  was most pleasing to me sonically. I actually settled on some inexpensive drivers from American Audio, Sound Barrier and Pyle (woofer, midrange and bullet tweeter) and this was like 25-years ago. (back then, I had MLSSA software at my disposal for audio analysis)

Crossover: DIY passive 2nd order, 3-way  (Dayton Capacitors, Inductors and L-Pads)

Interconnect Cables: DIY Microphone shielded cable terminated with appropriate gold plated plugs

Speaker Cables: DIY 12awg Copper 8ft

Primary Power Amplifier (Tube): DIY  VTA ST-120 with KT-88 and Auto-bias

Alternate Power Amplifier (MosFet): Alesis RA-500

Preamp:   DIY Zero Gain Passive Attenuator and Wafer SW Rotary input selector

Line Amp: FX Tube 01

CD Deck: Pioneer PD-4500

Reel to Reel: DIY restored  TEAC A3340S   (I use ATR Tape)

Recording Line Amp: DIY Solid State with EQ and built-in 400Hz Sine Wave Oscillator

Music Server / DAC: DIY Raspberry Pi3, Allo Boss, 2TB Hard-Drive (Synogy NAS Backup)

Bluetooth Receiver: 1Mii B06Pro+ 5.1  with LDAC

Power Management and Conditioning: DIY Latching Mains Power Conditioner with Surge/Spike/RFI Suppression, Servo Controlled Variac, and Linear 5V 3A power supply for RPi3 music server / DAC. Sequenced Soft-Start power-up for system devices. Z-Wave voice controlled power switch via  “Alexa”

Music Player:  Volumio

Remote Controller:  Dedicated Fangor 10” Android 11 Tablet

Listening Room Size / Treatment: (W x L x H) 12’ x 36’ x 9’, Front Wall heavy drapes floor to Ceiling, rear wall light drapes floor to ceiling, Carpeted Floor, Fiberglass Acoustic Tile Ceiling, Bookshelves left and right.

Dedicated Test Instrumentation: Room EQ Wizard (REW), miniDSP UMIK-1, Radio Shack SPL Meter