The ultimate dual 500 "rising from the ashes" build

grapplesaw · Dec 30, 2015

Hello all

This is the much awaited Dual 500 / D-500 "everyone welcome" thread. I have owned a Dual 500 for about 30 years. I had wanted a mate to it for some time as may have been observed by my posts in other threads.

Thanks to Perry and his recent score from Hawaii, of which I just returned from - not to rub it in, I am now the proud owner of 1 and 3/4 dual 500's to add to my existing unit. One is complete and the other has no face plate and who knows what else. The units arrived in two 40' shipping containers , well two very well double boxed packages. Having arrived at the beginning of December they waited patently for me to return home at my drop ship place.

I hope to engage all of you reading to comment of the steps we will go through renewing these units.

I was going to wholesale change these units internally. I have now toned that done upon good advice from my friend Nick THD+N. He pointed out that these are so rare that I should keep them close to stock and maintain the original boards. Sorry Joe no test puppy here for you board. I will however go full complementary output.

grapplesaw · Dec 30, 2015

First step is take it apart. If any one knows how Phase linear Serial numbers work please pipe in

This unit is 1002. I am making up that it is #2 built. She is named Val

That's are many parts with date codes from 1977. The control boards are consecutive part numbers.

Here is some history on the 500

http://www.phaselinearhistory.stereomanuals.com/d500amp.htm

grapplesaw · Dec 30, 2015

This unit has many issues. The last person had no idea about how it worked. There was only one RCA410 installed and it was in the wrong slot. The very good news is the control board and meter board are in great shape.

grapplesaw · Dec 30, 2015

So here is the tear down

laatsch55 · Dec 30, 2015

That's a lot of parts....

grapplesaw · Dec 30, 2015

Here are a few questions to answer

-Which op amp to use? I have some Opa627 I would like to try or the OPA134

The stock is lf356 this one has 1-lf351and1-lf357. Go figure!!

The main control board pl32 is the same as a pl36 with the addition of a high frequency control section in the middle. This is best used to deal with ultra high frequency feed back like that you get in a PA system mic feed back not much good from home use.

-From make ully Complementary or Quassi(stock) setup. I want to do fully complementary set up.

-Move DC relay closer to backplate

-powder coat frame. I think better that paint.

Northwinds · Dec 30, 2015

Been waiting for this thread patiently. What a beautiful monster amp!!!!!

grapplesaw · Dec 30, 2015

Some interesting things. Straws on the transformer bolts??

Better shot of name tag

Here is the relay setup

Volume controls knobs are silver but they are same marking and looks

[http://www.basspig.com/D-500 mods.htm=CONFIG]23291[/ATTACH]

grapplesaw · Dec 30, 2015

Going to put in new backplane components. I have new transistor mounts. New Cap's and other resistors and diodes.

The stock has .39 ohm emitter resisters.

Any one has an opinion on using .33 ohm instead??

150 volt main Caps but I have photo attached showing blue filter cap on the main cap. Any idea if this required??

Here are two large yellow caps on the high frequency section. These are not on you unit or the parts unit.

laatsch55 · Dec 30, 2015

Are there caps on the rectifier??

grapplesaw · Dec 31, 2015

laatsch55 said:

No.
They across the +/- terminals on the big caps
This recommended in an other web page.

http://www.tomsguide.com/forum/39810-6-redesign-carver-amplifier-phase-linear-corp

Exert from that
At an earlier time, I had replaced the original electrolytic capacitors with
much larger 45,000uF capacitors. Recent research made me aware that the ESR
of electrolytics is not so good above 1000hz, so I added 4.4uf of poly
capacitors across each power supply rail, to improve the ESR at higher
frequencies.

There are no caps across any of my units

laatsch55 · Dec 31, 2015

Makes sense...

grapplesaw · Dec 31, 2015

laatsch55 said:

Here is complete write up

http://www.basspig.com/D-500 mods.htm

WOPL Sniffer · Dec 31, 2015

grapplesaw said:

Damn, I was looking for those straws.... 80Lbs of coke and not a single straw in the house..... :violent1:

laatsch55 · Dec 31, 2015

Got a C-note???

WOPL Sniffer · Dec 31, 2015

NO.... I'm married.... twice........ I may have a dollar though....

laatsch55 · Dec 31, 2015

I was always told if ya couldn't roll a c-note to do your coke ya couldn't afford it.....

Gepetto · Dec 31, 2015

grapplesaw said:

Insulating the ferrous transformer bolts from the laminations reduce eddy current losses in the transformer. It is usual design/fabrication practice in E-I core transformers. Looks like a feeble attempt at doing this.

Northwinds · Dec 31, 2015

I am a huge fan of Baroque pipe organ music so it was quite refreshing to hear you mention the King of Instruments. It has to be the organ by itself with no accompaniment though. I don't like mixing pipe organ with strings or reeds, it takes away from the impact. I also prefer the minor key stuff!! That shit just makes me smile and you have to have an amp with major power and headroom to get the gist of what it is actually like when it's played live. Where your whole body shakes

Gepetto · Dec 31, 2015

grapplesaw said:

The ESR of the bulk caps is much, much better than those 4.4uF caps at any audible frequencies. The 4.4uF caps do no harm but also don't do anything that will matter in the audible spectrum.

The ultimate dual 500 "rising from the ashes" build

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