White Oak Audio Design - Model ONE 1000 Watt Stereo Amplifier

[mlucitt]

Combined 425 rail voltage

Glen, sorry for the confusion. The 425V Total Voltage Rating is from AnTek, the manufacturer, it is not the Rail Voltage or the Combined Rail Voltage. This "total" number includes the dual 125V Primary windings and the two additional Secondary Windings of 12VAC each. The main secondary of the AnTek AN-15475 is made up of two 75V Windings. When they are center tapped, these combined windings produce 150VAC, or +75VAC and -75VAC going to the Bridge Rectifier.
Then, rectification to DC (75V multiplied by 1.414), equals +106.05VDC and -106.05VDC produced. After passing through (4) 15,000uF caps (2 per Rail) for a total of 60,000uF, the Rail Voltage is a steady +106VDC and -106VDC.
The Power Transformer should draw about 12.5 Amps (1500W divided by 120VAC) The DC Rail Current should be just under 8 Amps.

 

[mlucitt]

Here are the progressive build pictures of the first of two Rev D Meter PCBs. I think we have these wrung out now.
There are 14 LEDs for each meter. Because Joe pre-bent them, they can only be install with the proper polarity.
I found that these LEDs fit the holes very well. By soldering the component side of only one leg of all the LEDs, you can go back and align them perfectly. Then solder the other leg. The White color is applied to the PCB when manufactured. It is impervious to 99.9% Isopropyl Alcohol and Flux Removing Solvent.


This is the rear view of one of the two Meter PCBs. JP1 is a Do Not Populate (DNP) because this Jumper Setting for Meter Sensitivity will be controlled by a switch on the Faceplate. Additionally, C2 and R5 were used in development and are also DNP.


Next up will be the Power Control PCB...

 

[grapplesaw]

Glen, sorry for the confusion. The 425V Total Voltage Rating is from AnTek, the manufacturer, it is not the Rail Voltage or the Combined Rail Voltage. This "total" number includes the dual 125V Primary windings and the two additional Secondary Windings of 12VAC each. The main secondary of the AnTek AN-15475 is made up of two 75V Windings. When they are center tapped, these combined windings produce 150VAC, or +75VAC and -75VAC going to the Bridge Rectifier.
Then, rectification to DC (75V multiplied by 1.414), equals +106.05VDC and -106.05VDC produced. After passing through (4) 15,000uF caps (2 per Rail) for a total of 60,000uF, the Rail Voltage is a steady +106VDC and -106VDC.
The Power Transformer should draw about 12.5 Amps (1500W divided by 120VAC) The DC Rail Current should be just under 8 Amps.

This will easily match the 700
We’ll be following you Mark
I’m a bit jealous of you getting to pioneer this amp and I am sure it is in good hands with you at the helm

 

[mlucitt]

This will easily match the 700
We’ll be following you Mark
I’m a bit jealous of you getting to pioneer this amp and I am sure it is in good hands with you at the helm

I believe the difference in the Power Supplies is that the PL700 used a 1000VA Transformer, the WOA Model ONE will use a 1500VA Transformer, a 50% increase in Wattage (assuming a Power Factor of 1). Additionally, the Phase Linear transformers were I-E Steel Cores and the Mode ONE transformer is a Toroid. My understanding is that the Toroid has higher Magnetic Flux and more stable Output Voltage, meaning less Voltage Drop during high loads.

Thank you for the vote of confidence. I am humbled to have S/N 2 in-house. And at the same time I have to admit it is exciting to be involved at this early stage of production. Also, a little scary to be pointing out minor errors to "the Big Guy".
Please know I am sharing everything as I proceed and hopefully soon, everyone on the Forum will have the opportunity to purchase the Kits to assemble their own WOA Model ONE.
To me, this amplifier is reminiscent of the early Acoustic Research amplifiers; except the components are not from the 1960's. Joe has spec'd the best quality components available at any price, just like the PL400/PL700 Upgrade Kits.

 

[George S.]

I like fast responding and unbreakable LED meters over mechanical meters. The ones Joe has engineered for the 400 and 700 S2 WOPLs are fantastic.
He has the 400 meter calibration dialed in perfect, as is the 700 meter with the 700's attenuation switch.
Looking forward to seeing the finished product.
Joe, it's amazing what you've accomplished with the WOPLs, and now this.
Thank you.

 

[mlucitt]

I like fast responding and unbreakable LED meters over mechanical meters. The ones Joe has engineered for the 400 and 700 S2 WOPLs are fantastic.
He has the 400 meter calibration dialed in perfect, as is the 700 meter with the 700's attenuation switch.
Looking forward to seeing the finished product.
Joe, it's amazing what you've accomplished with the WOPLs, and now this.
Thank you.

Joe and I had this meter discussion. Part of it was technical, but in the end we agreed that we both liked to watch big swinging analog meters. Turns out that LED meters would have been much easier and cheaper to engineer and design in-house. But to go with custom analog meters, Joe had to go overseas. They are very well-made and very pretty, but they were a pain to source and they are expensive. That goes to show you how dedicated Joe is when he makes a design decision.

 

[grapplesaw]

I believe the difference in the Power Supplies is that the PL700 used a 1000VA Transformer, the WOA Model ONE will use a 1500VA Transformer, a 50% increase in Wattage (assuming a Power Factor of 1). Additionally, the Phase Linear transformers were I-E Steel Cores and the Mode ONE transformer is a Toroid. My understanding is that the Toroid has higher Magnetic Flux and more stable Output Voltage, meaning less Voltage Drop during high loads.

Thank you for the vote of confidence. I am humbled to have S/N 2 in-house. And at the same time I have to admit it is exciting to be involved at this early stage of production. Also, a little scary to be pointing out minor errors to "the Big Guy".
Please know I am sharing everything as I proceed and hopefully soon, everyone on the Forum will have the opportunity to purchase the Kits to assemble their own WOA Model ONE.
To me, this amplifier is reminiscent of the early Acoustic Research amplifiers; except the components are not from the 1960's. Joe has spec'd the best quality components available at any price, just like the PL400/PL700 Upgrade Kits.

Oh no
The phase linears are 2000va transformers. I got that from the horses mouth

 

[grapplesaw]

1500va still more than enough and it will be interesting in what the toroidal transformers produce compared to traditional wind

I’m setting out to build a dual mono using four toroidal 650va and 80 volt each leg common tap.so extracting 5ish watts

it’s something Lee , Pery and I have started but no one finished 20 outputs per channel and possibly in separate chassis driven by possibly a rev e cut in half

Mark you will be finish long before me and yours is going to be great

 

[laatsch55]

Those toroids we got from SoCal will get ya 118 on the rails....

 

[grapplesaw]

Those toroids we got from SoCal will get ya 118 on the rails....

Thanks Lee
That was 80v before the bridge rectifier Should have extended it

 

[laatsch55]

192 Ct'd IIRC...

 

[MarkWComer]

I like fast responding and unbreakable LED meters over mechanical meters. The ones Joe has engineered for the 400 and 700 S2 WOPLs are fantastic.
He has the 400 meter calibration dialed in perfect, as is the 700 meter with the 700's attenuation switch.
Looking forward to seeing the finished product.
Joe, it's amazing what you've accomplished with the WOPLs, and now this.
Thank you.

They really topped off the look of the S2 amps, and switchable between dot and bar is a plus. Those segments are available in different colors, too!

 

[mlucitt]

The Power Control PCB Assembly. First the Resistors...

Next are the smaller parts.


Finally, the larger pieces.

Notice the "Vacation" Switch? It removes all power from the amplifier, no standby power. That's why this is the "Brains" of the WOA Model ONE.

Next up will be the Output Relay Control PCB.

 

[mlucitt]

Oh no
The phase linears are 2000va transformers. I got that from the horses mouth

Which horse are you talking about? I don't know about that, but I do know that 2000VA at 120V will pull 16.66 Amps. Most home wiring breakers are 15 Amps. They would be getting warm if there are other loads on that Outlet circuit.
And the label on the back of the Phase Linear 700B's that I have say "Max Power In 960 Watts". I will put an ammeter on the line cord "Hot" and see what the amplifier pulls at idle and fully cranked and see what I measure. I will let you know.

 

[grapplesaw]

Which horse are you talking about? I don't know about that, but I do know that 2000VA at 120V will pull 16.66 Amps. Most home wiring breakers are 15 Amps. They would be getting warm if there are other loads on that Outlet circuit.
And the label on the back of the Phase Linear 700B's that I have say "Max Power In 960 Watts". I will put an ammeter on the line cord "Hot" and see what the amplifier pulls at idle and fully cranked and see what I measure. I will let you know.

That is a great idea Mark
the horse’s mouth is the captain , Bob Carver
we’ve had a few interesting discussions including Casode transistor configuration for amps. Bob and my brother did a lot of business back in the 70’s and he helped develope Bob’s amp for the PA market, not so much in design but in torturing them at rock concerts. . He was with Kelly Delong Sound then and Bob was just starting out with his business.

Here we are at a meet up at Innovative Audio with Nando in 2019. Bob signed a few pieces of some of my builds with white oak inside. He was quite impressed with what Joe had come up with for retrofitting his amps.

 

[Gepetto]

Nope, not 2000VA, not even close.

I designed and had built a bigger version of the PL700 transformer, using a deeper stack for more core area and larger gauge wire everywhere. It ended up being a 960VA transformer and performs much better than the original PL transformer from a load regulation perspective.

 

[grapplesaw]

Nope, not 2000VA, not even close.

I designed and had built a bigger version of the PL700 transformer, using a deeper stack for more core area and larger gauge wire everywhere. It ended up being a 960VA transformer and performs much better than the original PL transformer from a load regulation perspective.

Well you know Bob is a salesman Thanks Joe for clearing that up
He really thought the WOPl was impressive

 

[Gepetto]

Well you know Bob is a salesman Thanks Joe for clearing that up

That old line Glen. “Never confuse selling with installing “

 

[mlucitt]

Here is the Output Relay Board. It went together so well I forgot to take assembly interval pictures. It is fairly uncomplicated but uses off-board regulated power. The amplifier outputs are brought in on 1/4" Faston Tabs and the copper layer for the output audio signal is huge.



Next are the WOA-1000C Amplifier Boards.

 

[Gibsonian]

Just found this thread. I be following. Good choice on the swinging meters. Way better than LED's imo.