PL 700B Mods

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.

Thanks
Larry

Who is doing the work?

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

Larry

I'd leave the iron alone unless you want to redesign the power supply.

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

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.

Larry

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.

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?

Thanks
Larry

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.

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

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

Look forward to your reports on the new modified sound Larry.

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

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

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