[Bill Baker]

Hi Dave, I hope you don't mind me jumping in here and feel free to correct me if you don't agree.

I was just going to replace the white SoniCaps with the Platinum. Will that work?

 If you can swing it, I would recommend replacing the coupling caps with .22uF SoniCap Platinum rather than doing any bypassing on coupling capacitors. I am not a fan of bypassing coupling caps for various reasons. If using the Platium, there would be no need to bypass anyway. These are well worth the cost of the upgrade.

 To be honest with you, I have not used the upper end Mundorf (Silver/Oil or Silver/Gold) in the coupling positions of this amplifier. I have used them in many other applications in the coupling position and do very much like these caps.
 I would not say they are better or worse than the Platinum but definitely different.

 You can used the Mundorfs, SoniCaps or any other good quality capacitor to bypass the power supply capacitors (470uf x2). If you have extras, also bypass the B+2 supply. These will be somewhere around 150uF-220uF. Use one on each cap.

[Wire Nut]

Great!
The guy that owned it before me did all of your mods- plus; new Goldpoint pots, remove the balance, new tube sockets, etc.
I wanted to do a little to make it "my own" so I have purchased a pair of Vampire RCA input jacks & am waiting for some 22 awg pure silver ribbon hook up wire to replace the CD wiring on the unit. I also had walnut front & sides made... but the guy that did the laser thing included the word "Balance" so in honor of the platinum SoniCaps I will have a tiny plaque made that says "Platinum" in a script writing to cover it with.
I have put B-Quiet on the bottom inside & built am isolation stand out of hardwood that have also helped.
Just for fun I purchased Michael Wolff RCA's & a power cable for it- all in all it should sound & look great!

[Wire Nut]

For all- here is some good advice Dave gave on cleaning up the old solder:
De-soldering tips.

- I have tried a few different wicks, and prefer Chem Wick

http://www.all-spec.com/1/search/all/chem-wik?gclid=CIidru3bspoCFQVxFQodOlkmbw

And this product.

http://www.mgchemicals.com/products/400braid.html?PHPSESSID=950d0d2382c237b8aef884c7fe8f91be

If your de-soldering wick leaves considerable residue, buy a better wick.

The process.

1.  Remove as much residual solder from the terminal area as possible.

2.  Apply heat to the individual leads and GENTLY pull with a needle nose pliers.  I have pulled too much and removed traces from circuit boards.

3.  Either apply heat when re-installing the new component OR use a very small diameter drill bit to remove the excess solder in the circuit board hole.

The process is very simple, but I encourage you to be quite gentle and work slowly.  De-soldering takes much more time than installing components.

[Wire Nut]

Well I installed the Platinum caps with no incident .
I have left the unit playing for 50 hours & can give a first report:
The music is much more "Open & airy" there is a lot more definition at every range of the spectrum. That was all as expected from the reviews... what I did not expect is deeper bass with more punch!!!
Holy cow, this is the best hundred and fifty bucks I have spent on my stereo.
I will post some more observations next week after 100 hrs of burn in.
Thanks for the great suggestion- it works.

[David Ellis]

Holy cow, this is the best hundred and fifty bucks I have spent on my stereo.

Wonderful!!

Yep, good coupling caps can do amazing things.  Great coupling caps (i.e. Sonicap Platinum) can be sublime. aa

And... I really don't know why more bass happens, but I noticed this too.  It wasn't a subtle change.

Dave

[Wire Nut]

Dave,
What would need to be done if at some time I wanted to be able to use KT88 tubes in my 302b?
Thanks

[David Ellis]

What would need to be done if at some time I wanted to be able to use KT88 tubes in my 302b

I really don't know.  I do know that some folks have amps that will accomodate both tubes.  I am fairly certain you could plug-in some KT-88 tubes, but I am not sure how long the the amplifier would function before it started to smoke. 

Also, I am not sure the KT-88 tube actually sounds better than the El34.  Yes, I am aware of the many variations.  I am also aware that I haven't performed a really good a/b test in the appropriate amplifier.  But, I did hear my speakers on some push pull KT-88 tubes, and thought it sounded better on my Svetlana El-34 Jolida at home.  Certainly there are many variables involved, but I perhaps it's fair to offer 1 crude data point.

Dave

[Bill Baker]

What would need to be done if at some time I wanted to be able to use KT88 tubes in my 302b?

 The Jolida 302 and 502 are the exact same amplifiers with the only difference being in the value of 4 resistors that allow proper biasing points for the EL34 or 6550/KT88 tubes.

[Wire Nut]

Could you tell me what those 4 resisters are & what the value would be to have the ability to play both 77 & 88?
Thanks so much!

[chrisby]

Could you tell me what those 4 resisters are & what the value would be to have the ability to play both 77 & 88?
Thanks so much!

since it's  been quite a few months since the above post, you may have already found the answer, or abandoned the quest,  but based on the generic 302/502B schematic, those numbers would be:

R14 &15 (and whatever numbers would apply to other channel)

302B = EL34 = 12K
502B = KT88 = 24K

This of course still doesn't answer your question if the KT88 operating points would be in an optimal region for KT77,

BTW,  has anyone tried the Steve Deckert CCE mod on their 302?  This mod is effective for that small group of power pentodes with internal separation between suppressor grid and cathode.  (e.g. the SV83 / 6N15N, or EL34).

In the case of the 302, it would mean replacing the jumper between pins 1&8 with a 1mF film cap.  I have yet to complete this on my own triode wired 302, but have received confirmation from the owner of a modded Dyna ST70 that it worked wonders.

[Bill Baker]

Could you tell me what those 4 resisters are & what the value would be to have the ability to play both 77 & 88?

 What I have found to work nicely is a 15k in this position. This has allowed me to use most EL34, KT77, 6550 and KT88 tube types.

[Wire Nut]

Guys, where would this 15K go? The reason I ask is I tried a set of the Gold Lion 77's and my unit would not work at all, I could not get a bias reading!
Thanks

[w1ngs]

I thought I'd join the forum as I'm helping Chris with his 302.

I hope you mean 1?F and not 1mF Chris!

Cheers

EDIT: It would appear this forum does not support extended ASCII. The "?" should be a Greek letter mu.

[chrisby]

I thought I'd join the forum as I'm helping Chris with his 302.

I hope you mean 1?F and not 1mF Chris!

Cheers

EDIT: It would appear this forum does not support extended ASCII. The "?" should be a Greek letter mu.

well, as by now you've seen the piece - those are 1mF Solen films,  IIRC

[chrisby]

Guys, where would this 15K go? The reason I ask is I tried a set of the Gold Lion 77's and my unit would not work at all, I could not get a bias reading!
Thanks

Well, just as there appear to be at least 2 versions of the power supply PCB,  there may also be an uncertain number of variations on the main board containing the input/driver and output stage bias circuits.

Dave / Bill can correct me on this, but on both versions of schematics that have been posted in this thread, I believe you'll find them at R14 and R15 (i.e. between the bias trim pots and ground bus). In the case of my 1990   oops - that should be 1999 vintage 302B, they are clearly labeled on the PCB.

So in other words, you'd replace what ever value of fixed resistor is resident that site ( i.e. according to schematics posted elsewhere could be either 12K or 20K for 302 with EL34s) 
 

[w1ngs]

Chris: mF is millifarads, while uF is microfarads. There are 1000uF in 1mF, so it is best to be clear.

[bookerhm]

I did a bonehead thing and failed to bias my tubes causing a meltdown of my left channel transformer.   I decided it would be a good idea to upgrade the transformers and chose Hammond 1650 P based on reading a post somewhere.  I have a slight problem with the install though.  The Hammond comes with 2 more wires for impedance.  The Jolida transformer had 1 brown 8 ohm wire, one Blue 4 ohm wire, and a black 0 ohm wire.  The hammond transformer has 2 wires for 4 ohms and 2 wires for 0 ohms.  How would I go about soldering the new amp with what appears to be a duplication of wires? 

Thanks,

booker

[w1ngs]

Check the hammond data page for the 1650P:

http://www.hammondmfg.com/1608.htm

The wiring diagram shows two separate interleaved windings, one with a single 4ohm tap, the other with the 4 and 8 ohm taps. The intention of the designer here is for the two 0ohm and 4ohm wires to be put in parallel; IE: Green to Green/Yellow and Black to Black/Yellow for all situations requiring a typical 4 or 8 ohm output setup. For 16 you end up wiring it all differently, but in the case of keeping the JoLida original, the former wiring configuration is desired.

Once you've wired the two four ohm pairs in parallel, you'll end up with three output wires, 0-4-8, as you need for your application.

Hope this helps!