Question for Joe or builders with appropriate test equipment.

stetter

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174
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Tower, MN
#42
Lee have you seen the new Kevin Garnet commercial about Royal Crown, I ask because I want to make sure you are getting enough water
 
Joined
May 26, 2013
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636
Location
St. Louis, MO.
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Born and Raised In The 700 Watt Club.
#46
Here is a link to the WOPL power cords I use. I buy 5-6 at a time. they are brand name, very high quality cords. These don't get too warm when you crank up the volume to Mach 10.

https://tinyurl.com/y552fyvt
Here’s what I really want to know. What kind of MUSIC, or hell....better yet SPEAKERS do you guys listen to than can sustain the kind power driven at Mach Ten long enough to get the power cord warm before your ears don’t explode FIRST?? I can see runnin a Vacuum cleaner which pulls enough amps for an extended period of time causing the cord to warm, but that wouldn’t kill my ears. And at that volume, you’d have to be livin in the middle of nowhere. I try n pull that shizz, and my neighbor’d be calling the cops in 5 minutes flat! Unless you guys went deaf a long time ago or just plain have Really Awesome neighbors. Just sayin.....LOL!
 

mlucitt

Veteran and General Yakker
Joined
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#47
Most of my music is live recordings (hard to record, but brutally honest) of classic rock. You know, the stuff we all know the lyrics to, or maybe no lyrics. Speakers are JBL Pro clones of the now obsolete 4196B, a two-way, 4 cuft, all-purpose system with a 15" woofer, 2425J compression driver, and 2370A horn, connected via a 3110 passive crossover. I built the enclosures and covered them with black truck bed liner. Ugly, but man they sound great at Mach 10!
 

laatsch55

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Gillette, Wyo.
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Halfbiass...Electron Herder and Backass Woof
#48
Waiting on Columbus.......there's a classic live album. I don't do live albums at Mach 10.....9 maybe....Shpongle now....they're Mach 10...
 

George S.

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#49
Could we see a picture of your three-prong cord PL2000? I have attached a Service Manual for the PL2000/2000 II and page 9 has a schematic of the power supply. I do not see a three wire power cord, but yours could have been a special order. Further, the 117VAC in the PL2000 immediately becomes the primary of a 24VAC center-tapped transformer; that means the rest of the unit is below fatal shock threshold and lightning continuity. I would much rather have the three-prong cord and safety ground connected to the amplifier, where there are fatal shock thresholds throughout the entire chassis.

Now, if you plug your amplifier power plug into the preamp accessory outlet, you will still not be grounding your amplifier because the accessory jacks are two-prong. However, the designer warned us not to exceed the wattage allocated for the accessory jacks and that is typically around 400 Watts maximum per outlet. Any WOPL 700 is going to consume greater than 400 Watts, so the power cord should go to a wall outlet or a dedicated power strip where it can be properly grounded/earthed.

The subject of safety grounding the chassis of a rebuilt PL400/700 (WOPL) has been a debate here for quite a while. Because I run a business and make a profit from my customers, I have contacted a lawyer regarding my liabilities. He stated that as long as I am following 'generally accepted practices' in my construction, I am fairly safe. That includes a three-wire safety cord and a safety ground on the chassis of all the amplifiers I rebuild. You are welcome to do as you wish, of course. I inform all my customers that the amplifier is safety grounded and if there is hum it is due to their house wiring, not the amplifier. I refer them to Section 250.4 of the National Electrical Code (NEC) and Standard 467 of the Underwriters Laboratory (UL).

With regards to signal hum, I do not ground or connect my signal coax input shields to chassis ground or each other. I allow the shields to enter into the WOA Dual Mono Control Board, and the separate shield/common connections flow to the separate WOA Backplane boards and then to the STAR ground that ultimately connects to single point ground on the chassis. For the two chassis ground points, I scrape the paint on the chassis, use sharp star washers, and crimp/solder the insulated terminal connector onto 16 gauge wire. I also add an AC-rated 275V X2 (self-healing in case of arc-over) .1uF safety capacitor (mouser P/N 667-ECQ-UAAF104M) across the line and neutral legs, and two 300V Y2 (never fail short) .01uF safety capacitors (Mouser P/N 72-VY2103M63Y5US63V0) between neutral and ground/line and ground of the power input connections to reduce AC-related noise. This is by design and none of the amps I have built display any 60Hz hum, most often as a result of cable problems or poor shielding; or any 120Hz buzz most often caused by ground loops.
This is the only PL preamp I've ever seen in person, other than some I saw in a HI FI shop in the mid 70s, bought it from a pawn shop I think just outside Ft.Bragg NC about 30 years ago, so it may have been bought overseas and converted upon return. I'm fairly certain this is the cord it came with when I purchased it. I'm going to look at photos on the internet tomorrow and see if this is standard or not. Thanks for the detailed instructions on how you ground your builds. PXL_20201130_025447288.jpg PXL_20201130_025746734.jpg PXL_20201130_030308374.jpg
 

Billboard

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#50
My WOPL 700b gets a regular work out at close to max output, yes I have fans on the back. Speakers are rated at 4 ohms, with a rather low efficiency rating of 90db. Speaker Max power, whatever you have. Neighbors? They’re cool.

Ohm model I
 

George S.

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Joined
Feb 18, 2020
Messages
253
#52
I've often thought about trying to build a set of Ohm model 1 clones, think I've read everything on the internet there is about them, but life gets in the way.
 

Billboard

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Messages
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#54
I've often thought about trying to build a set of Ohm model 1 clones, think I've read everything on the internet there is about them, but life gets in the way.
They are out there for sale, had a second set close to me go up for sale, somewhere around $500 in fair shape.

Don’t need a second set, so I passed. Keep looking, they are amazing, placement not critical, not very directional, as not so much of a sweet spot. Enjoy them as you walk around the house. Also Ohm still supports them with replacements at a reasonable cost.
 

George S.

Journeyman
Joined
Feb 18, 2020
Messages
253
#57
Could we see a picture of your three-prong cord PL2000? I have attached a Service Manual for the PL2000/2000 II and page 9 has a schematic of the power supply. I do not see a three wire power cord, but yours could have been a special order. Further, the 117VAC in the PL2000 immediately becomes the primary of a 24VAC center-tapped transformer; that means the rest of the unit is below fatal shock threshold and lightning continuity. I would much rather have the three-prong cord and safety ground connected to the amplifier, where there are fatal shock thresholds throughout the entire chassis.

Now, if you plug your amplifier power plug into the preamp accessory outlet, you will still not be grounding your amplifier because the accessory jacks are two-prong. However, the designer warned us not to exceed the wattage allocated for the accessory jacks and that is typically around 400 Watts maximum per outlet. Any WOPL 700 is going to consume greater than 400 Watts, so the power cord should go to a wall outlet or a dedicated power strip where it can be properly grounded/earthed.

The subject of safety grounding the chassis of a rebuilt PL400/700 (WOPL) has been a debate here for quite a while. Because I run a business and make a profit from my customers, I have contacted a lawyer regarding my liabilities. He stated that as long as I am following 'generally accepted practices' in my construction, I am fairly safe. That includes a three-wire safety cord and a safety ground on the chassis of all the amplifiers I rebuild. You are welcome to do as you wish, of course. I inform all my customers that the amplifier is safety grounded and if there is hum it is due to their house wiring, not the amplifier. I refer them to Section 250.4 of the National Electrical Code (NEC) and Standard 467 of the Underwriters Laboratory (UL).

With regards to signal hum, I do not ground or connect my signal coax input shields to chassis ground or each other. I allow the shields to enter into the WOA Dual Mono Control Board, and the separate shield/common connections flow to the separate WOA Backplane boards and then to the STAR ground that ultimately connects to single point ground on the chassis. For the two chassis ground points, I scrape the paint on the chassis, use sharp star washers, and crimp/solder the insulated terminal connector onto 16 gauge wire. I also add an AC-rated 275V X2 (self-healing in case of arc-over) .1uF safety capacitor (mouser P/N 667-ECQ-UAAF104M) across the line and neutral legs, and two 300V Y2 (never fail short) .01uF safety capacitors (Mouser P/N 72-VY2103M63Y5US63V0) between neutral and ground/line and ground of the power input connections to reduce AC-related noise. This is by design and none of the amps I have built display any 60Hz hum, most often as a result of cable problems or poor shielding; or any 120Hz buzz most often caused by ground loops.
Looking at PL2000s on the Bay, they all are 2 wire, so mine is a odd duck. I'm going to replicate your grounding scheme at the plug, thank you for the part numbers. The rest of my two amps are built exactly as you describe. Yup, this is a great forum. I'll post some photos once I get the amps upgraded.
 

mlucitt

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Joined
Jun 24, 2011
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2,124
Location
Jacksonville, FL
#58
Looking at PL2000s on the Bay, they all are 2 wire, so mine is a odd duck. I'm going to replicate your grounding scheme at the plug, thank you for the part numbers. The rest of my two amps are built exactly as you describe. Yup, this is a great forum. I'll post some photos once I get the amps upgraded.
You have a rare PL2000 Series II factory export wired for 220V. I don't think the folks at PL offered (or contemplated) the PL2000 Series I would ever be exported, so I don't think that they made the Series I for 220V.
That small transformer (T1) has a dual 120V/220V primary. Clearly, the cable is a three-wire and to be in compliance with most 240V countries, the earth (green) wire is securely connected to the chassis. You can buy a 120V to 240V step up transformer and keep your preamp original, or you could convert it back to USA specs. Just don't plug it in to 120V, it will not be happy. Based on the zip-tied cloth covered wiring, I would say it is still factory wired for 220V operation.
Pretty sure about this, but I would measure to be safe: One primary winding is Brown and Brown w/ Yellow stripe, the other primary winding is Blue and Blue w/ Yellow stripe. You have the Brown w/ Yellow stripe and Blue connected together and the one wire of the AC voltage going to Brown and the other wire of AC voltage going to Blue w/ Yellow stripe which places the windings in series for 220V operation. To convert it to 120V operation the primary windings need to be in parallel. When transformer primary windings are connected in parallel, the phase must be correctly observed or the transformer will become damaged. To do this properly, you would connect one wire of the AC to both Brown and Blue twisted together and the other AC wire to both Brown w/ Yellow stripe and Blue w/ Yellow stripe twisted together. This is a standard PL convention, I have wired PL700 Series II amplifiers for dual voltage operation and that is how it's done.
Personally, I would install a 'dual voltage' switch after the fuse and make the primary voltage selectable. You would need to drill two small 1/8" holes and a small 'window' to mount the switch inside the unit. I can send you the switch and the instructions how to wire it in, if you desire.
 
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