White Oak Audio Design - Model ONE 1000 Watt Stereo Amplifier

mlucitt

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#1
I am pleased to announce that I have purchased a new amplifier kit from White Oak Audio Design, the Model ONE. While there are some recognizable features, such as the PL700 Backplane Boards and Heat Sink Fins; this is a completely new design, engineered by Joe King (Gepetto). He can provide more information about the concept, the design goals, and the specifications. I will be doing the assembly and feedback, by his request, for continuous process improvement in real time. But I need your help...
I will be providing a narrative and pictures of the first-time assembly process, and I would appreciate constructive criticism and comments as I go through the steps of assembly. Please do not ask about availability and prices, that will be the domain of WOA, I am just the Technician. There are three parts to the Model One Kit:
1. Customer supplied parts. These are parts that are available at Mouser, non-stocked at WOA, or too heavy for WOA to ship (transformers).
2. The Mechanical Kit. This is the sheet metal and hardware that forms the cabinet of the amplifier including the Faceplate.
3. The Electronics Kit. This contains the eight PCBs and all the components to assemble them. Documentation (BOMs, Wire Lists, and tips) will be provided.
Additionally, if you want to build one, or more, of these kits you will need some special tools. More on that later.

Let me start out by saying this will be a monster of an amplifier. The main toroidal transformer is rated at 1500VA at 475V and weighs 35 pounds by itself. The Faceplate is over 1/4" thick, 25% thicker than a PL700 faceplate. There are eight printed circuit boards to be assembled, all made in the USA. Enough of that.

Here are some pictures, "In the Beginning..." The Mechanical Kit:
05 Mechanical Parts 2.jpg

Mechanical Kit Hardware (26 Bags)
06 26 Bags of Small Parts.jpg

The Electronics Kit (113 bags) The Backplane Boards are already assembled and not shown.
11 (113) Bags of Parts in the Electrical Kit.jpg

The moderators may want to make this a separate Forum, it's up to them. This is my plan:
1. Assemble the two Meter PCBs so that I can attach the Meters to the Faceplate and put it in a safe place until needed for attachment.
2. Assemble the Power Control PCB, this is the "Brains" of the amplifier and sits in the middle of the chassis. Many wires run to this board, so it is critical.
3. Assemble the Output Relay PCB because Then I can attach it to the inside rear of the chassis, out of the way.
4. Finally, assemble the two WOA-1000C Amplifier PCBs because I previously had the two Backplane Board PCBs assembled and waiting in anticipation.

I will be happy to answer questions regarding the parts, assembly process, and the logistics involved with building this awesome beast. This has become my full-time obsession, I have retired from doing WOPLs, Phase Linear upgrades, or supplying Phase Linear parts (except for previous customers).

Let the process begin...
 

J!m

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#3
Is this 1000 watts stereo (1k per channel), 500 watts per channel or 1000 watts mono? Into 8 ohms?

Any provision for balanced input?
 

grapplesaw

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Great to see this project finally underway
mark what rail voltage will this be if you using this “The main toroidal transformer is rated at 1500VA at 475V”.
 

mlucitt

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Yes, it is a Stereo amplifier with 500 watts per channel at 8 Ohms. I don't know it that is RMS, dBm, dBV, dBW, or dB SPL. I know it will be a Mach 11 amplifier with a high neighbor piss-off factor and a high probability of Police visitation.

From Joe: "To bridge the amp, use the XLR inputs and swap the wiring polarity in one of the channels. You will have an in phase and out of phase amp output and the speaker goes from Channel A hot binding post to the Channel B hot binding post. That was a design intent from the get go."

and

"On each control board, there exists a 6 position dual row header with jumpers.
Using these 6 jumper positions, you can:
Provision the XLR connections as either straight through or reversed.
Provision to run through the volume pot on the front or bypass it and go straight through (direct).
Provision whether the RCA input is in control or the XLR input is in control.
Provision to invert the RCA input.
I believe it has all the flexibility that anyone would desire (but I am sure that someone may argue that I don’t have some base covered)."

I have not seen the full schematic yet.
The transformer will output +150VAC and -150VAC converting to DC gives rails of about +212VDC and -212VDC. So a swing of 424V!

Thanks for the comments!
 

grapplesaw

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Yes, it is a Stereo amplifier with 500 watts per channel at 8 Ohms. I don't know it that is RMS, dBm, dBV, dBW, or dB SPL. I know it will be a Mach 11 amplifier with a high neighbor piss-off factor and a high probability of Police visitation.

From Joe: "To bridge the amp, use the XLR inputs and swap the wiring polarity in one of the channels. You will have an in phase and out of phase amp output and the speaker goes from Channel A hot binding post to the Channel B hot binding post. That was a design intent from the get go."

and

"On each control board, there exists a 6 position dual row header with jumpers.
Using these 6 jumper positions, you can:
Provision the XLR connections as either straight through or reversed.
Provision to run through the volume pot on the front or bypass it and go straight through (direct).
Provision whether the RCA input is in control or the XLR input is in control.
Provision to invert the RCA input.
I believe it has all the flexibility that anyone would desire (but I am sure that someone may argue that I don’t have some base covered)."

I have not seen the full schematic yet.
The transformer will output +150VAC and -150VAC converting to DC gives rails of about +212VDC and -212VDC. So a swing of 424V!

Thanks for the comments!
Thanks Mark
I guess I don’t quite get it
Combined 425 rail voltage should yield about 1540 watts per channel not 500. The dual 500 secondary out put is 87 volt which translates to 120 volt per rail or 240 combined
anyway no worries and hope your build goes fast. We‘ll be following you
 

NeverSatisfied

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#11
Hi gents, hope all are well and had great thanksgivings!
Dang.....disapear for a couple months and return to this exciting news.
Congrats on the new project, looks like it will be a monster.
Question for Joe or Mark, any chance this will be available in a switchable dual voltage ?
 

Gepetto

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#12
Hi gents, hope all are well and had great thanksgivings!
Dang.....disapear for a couple months and return to this exciting news.
Congrats on the new project, looks like it will be a monster.
Question for Joe or Mark, any chance this will be available in a switchable dual voltage ?
Strappable, not switchable...
 

Gepetto

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Thanks Mark
I guess I don’t quite get it
Combined 425 rail voltage should yield about 1540 watts per channel not 500. The dual 500 secondary out put is 87 volt which translates to 120 volt per rail or 240 combined
anyway no worries and hope your build goes fast. We‘ll be following you
It has very robust +/- 108 VDC main rails...
 

MarkWComer

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#14
White Oak’s next logical step! The bar for “world class” has taken a significant jump upward!

I’d love to build one, but there’s no way I could actually use something that big- as it is, I have to throttle my 700 back.

Exciting, though… What a beautiful beast!
 

J!m

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White Oak’s next logical step! The bar for “world class” has taken a significant jump upward!

I’d love to build one, but there’s no way I could actually use something that big- as it is, I have to throttle my 700 back.

Exciting, though… What a beautiful beast!
It's not at all about ultimate power, but rather T O N S of headroom, which really opens up the music. And running dual mono, with extremely short speaker cables, controls the speakers far better (increased "damping factor") so all good.

I'm at roughly 500 watts per side now and listen to 50 tops. But that change from 200 watts of headroom to 450 watts of headroom (and increased speaker control) was a massive improvement. Massive.

I believe these WO designs have significantly lower noise than the Counterpoint amps I'm now using. I'm tuned in because I was thinking of going to a pair of AHB2 amps from Benchmark but this may be the path forward for me...
 

MarkWComer

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#19
It's not at all about ultimate power, but rather T O N S of headroom, which really opens up the music. And running dual mono, with extremely short speaker cables, controls the speakers far better (increased "damping factor") so all good.

I'm at roughly 500 watts per side now and listen to 50 tops. But that change from 200 watts of headroom to 450 watts of headroom (and increased speaker control) was a massive improvement. Massive.

I believe these WO designs have significantly lower noise than the Counterpoint amps I'm now using. I'm tuned in because I was thinking of going to a pair of AHB2 amps from Benchmark but this may be the path forward for me...
Yes- I absolutely understand about ridiculous amounts of headroom, understand it fully. I do have an occasional session where I get up to maybe 120 watt peaks, and the 700 handles it well enough, no listening fatigue, no signs of stress other than the cooling fan kicking into high gear, and quite truthfully, even my 400 was doing well enough.

But… supposedly the 700 after a full WOPL upgrade is a 500 watt/channel amp, correct? Essentially, I already have this, short of the expanded power supply, so in effect there’s no “Phase Linear” left of this amp other than the faceplate and transformer. I actually wondered why White Oak didn’t do the “Model One” a long time ago, but I see that the line of progressive improvements have finally led to this. Yes, I drool over this, but understand that what I have in the gear that I have is exceptional.
 

J!m

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#20
Could not agree more.

I am in the same place with deciding on next steps for amps, Benchark, or potentially this project.
Maybe you'll be building four of them, based on the quality of your assemblies I've seen so far... assuming we go this route over Benchmark.

I'll make my own face plates of course (no meters) but maybe...
 
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