PL 700B Mods

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speakerman1
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PL 700B Mods

Post by speakerman1 » Wed Dec 29, 2010 10:29 am

I'm about to send my 700b out for mods. Changing caps and the DC mod. I was also wondering if changing the present transformer to a toroidal one make a difference. Also would changing the big caps to an audiophile cap improve the sound.

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Larry

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Re: PL 700B Mods

Post by TNRabbit » Wed Dec 29, 2010 10:33 am

Who is doing the work?
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Re: PL 700B Mods

Post by speakerman1 » Wed Dec 29, 2010 10:40 am

A guy named Lee. He just did a PL 3300 pre for me and it sounds great.

Larry

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Re: PL 700B Mods

Post by BillD » Wed Dec 29, 2010 7:56 pm

I'd leave the iron alone unless you want to redesign the power supply.
It should sound like it isn't there!
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Re: PL 700B Mods

Post by speakerman1 » Mon Feb 14, 2011 11:44 am

We are. I did find some Black Gates and we are doing a LED light mod and the DC mod. It was sounding great. I hated to send it out. I know it will sound better. Did you see the one on ebay that went for 1200.00.

Larry

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Re: PL 700B Mods

Post by speakerman1 » Sun Feb 27, 2011 8:08 am

Lee found a strange mod in my amp. Has anyone seen or heard of this. Where some diodes were soldered into the board. The one leg was unsoldered and connected to a resistor and the end of the resistor was placed in the hole on the board. He was slightly taken aback at what my amp could do against one of his modded amps. If you can tell me what the mod I'm describing is for. I would appreciate it.

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Re: PL 700B Mods

Post by BillD » Sun Feb 27, 2011 2:27 pm

That just sounds like a voltage tweak. Voltage drops a fixed amount across a diode. Adding a resistor will increase the voltage drop a skosh.
It should sound like it isn't there!
There is a difference between hearing and listening...
Making life enjoyable through expensive electronics.
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Carver: C-4000 & C-1 preamps, PSC-60 preamp/tuner, TX-11a tuner, M-400 (2), C-500, M-500, M-500t, M-500t Mk.II, A-500x, AL-III loudspeakers (2 pr.)
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Re: PL 700B Mods

Post by speakerman1 » Sun Feb 27, 2011 3:03 pm

He had never seen it before and he has done a bunch of mods on a bunch of PL gear. My next question would be why?

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Larry

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Re: PL 700B Mods

Post by BillD » Sun Feb 27, 2011 4:00 pm

Well, not seeing the circuit, I can't say for sure, but it's probably a voltage sensitive thing (transistors turning on). Most people just use multiple diodes in that case, but who knows. If your man takes them out and the amp doesn't work, then you'll know, won't you? All I know is that a resistor isn't going to do anything wild (they are benign devices) so they aren't hurting anything as long as your amp works.
It should sound like it isn't there!
There is a difference between hearing and listening...
Making life enjoyable through expensive electronics.
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Carver: C-4000 & C-1 preamps, PSC-60 preamp/tuner, TX-11a tuner, M-400 (2), C-500, M-500, M-500t, M-500t Mk.II, A-500x, AL-III loudspeakers (2 pr.)
Sunfire:Theater Grand III processor, Ultimate Receiver, Cinema Grand Signature 400 ~ seven, True Subwoofer Mk. II, D-10 Subwoofer

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Re: PL 700B Mods

Post by speakerman1 » Sun Feb 27, 2011 4:41 pm

In the Spec department it was right up with his for a 32 year old amp. I thought that wasn't to bad. Ok thanks for the reply I appreciate it.

Larry

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Re: PL 700B Mods

Post by speakerman1 » Sun Mar 27, 2011 3:55 am

Well he is done with the amp. He used the same equipment to measure the watts when he started. He was getting about 425 wpc before it clipped. Last night he got 500 wpc and it never clipped. He didn't change the rail voltage. He changed a bunch of caps including the PS caps. He said he had never heard an amp that load. I trust this guy he is a good friend and there is no BS about him at all. So I am waiting for it to come home. He said the Black Gates sound great. Wish I could have found more and afforded more. I now have blue meters and an IEC connector. Plus he did the DC voltage mod. And new binding posts. He did this as a favor so it isn't like he would blow smoke because of the money. It blows his Spec 2s away. He just bought 2 700Bs and is going to try to get the same results out of them. He is also going to send a PL 4400 with it that he will go through.

I had a PL 3000 before; but not enough hook ups for my rack. Also the Phono stage had no warmth at all. I was not happy with it. We shall see what it all sounds like going through the Norman Labs I'm about to mod.

Larry

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Re: PL 700B Mods

Post by kingman » Sun Mar 27, 2011 8:13 am

Look forward to your reports on the new modified sound Larry.
In reality, it only matters what it sounds like to YOU!!!

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Re: PL 700B Mods

Post by speakerman1 » Thu Mar 31, 2011 1:22 pm

Hi is getting attached to it. He said some load bass blew 2 300 watt bulbs. When I was about to send it out I had purchased some Audio Alchemy gear it had my tubed CDP sounding very nice. I have some tapes to load and print then the speakers come in the garage for a make over. Will see what I have then. I think I will take is to my cousins farm and try it out since I live in town. Don't think I can push the Norman Labs to 500 watts continuous though.

Are there any thoughts as to how the watts jumped to 500?

Larry

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Re: PL 700B Mods

Post by speakerman1 » Fri May 06, 2011 8:58 am

Well it is home. I got it yesterday. It sounds like a different amp. Very defined. Some of the highs perk my ears. I had it almost half and my floor was shaking from the bass. It is so clear it isn't funny. I'm having a hard time hearing at the moment. I jammed for a while. While it was gone I modded my Norman Lab Model 11s. I pulled all the CBs and the tweeter switch. I went with a simple 2nd order x-over. New Solen caps and changed the hook up wire to 12 ga silver plated OFC.

The mods to the amp. It has been gone so long; but I know I didn't have the clarity I have now. Lee said the Black Gates did help. Plus doing all the other mods. . I am really proud of it. It sounds very good to me. Well worth the wait and money. I am smiling this morning.

Larry

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Re: PL 700B Mods

Post by speakerman1 » Thu Oct 13, 2011 11:50 am

Well I'm about to send the 700B out again to have the White Oak mod done. We may go with wire wound non-inductive resistors on this upgrade. People are flocking to have this mod done. I forget what Joe said the THD is. The amps that he has done are getting very close to the 600 wpc range. Will be changing all the wires to the next larger gage and going with OFC Silver plated. We are looking for some 400 or 700 VU meters. Anyone know where I can get some?

Larry

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