Modify your Woo 6. . Sophia and EML 274B . Images pages 32, 33, 34 of int. and ext. and discussion of the SE . . .

[Brighten]

Quote:

Originally Posted by WittyzTH /img/forum/go_quote.gif Is the maxxed upgrade really worth for $450? If not, what is the budget upgrade I should ask Jack to put/change in my WA6SE to make it sound better?

Many say that the Sophia Princess rectifier tube has the biggest impact on the sound.

 

[WittyzTH]

couldn't agree more about the Princess. It sounds really great. but I still want other more best-bang-for-bucks upgrade.

 

[peanuthead]

Quote:

Originally Posted by Brighten /img/forum/go_quote.gif Anybody know where to get a pair of RCA 6DE7s?

Woo Audio sells them for $17/pair.

 

[atbglenn]

Quote:

Originally Posted by jamato8 /img/forum/go_quote.gif I don't think that the measured power would be increased but the perceived does as you have a much better supply to each tube and therefore you have better dynamics due to the reserve for each tube being increased substantially. This would help with louder passages and clipping would be less of a problem but the volume from my 6 is more than enough, even on demanding passages.

I realize that the RMS power would not be increased, but would it be fair to assume the dynamic or peak power would be substantially increased? It sure seems like it.

 

[Skylab]

I tried a Sophia Princess Mesh-plate 274B in my CSP-2 recently - I was very impressed - it sounded great. Best current-production tube I have ever heard.

 

[dannie01]

Quote:

Originally Posted by takezo /img/forum/go_quote.gif hi danny, you should wait to see what's inside your stock wa6SE. the blackgates are verygood but not essential... i'd save the money and just upgrade several areas like the bypass caps (220uf/16v), bypass resistors and resistors between pins 2 and 6 with 0.5 watt carbon resistors. you can always change the values by going up but don't go down, especially with the voltage of the caps. (except the bypass where it should be fine to go to 6.3v instead of 16v. i get only 2+v thru the bypass section) for the power filter caps 150uf is insufficient imo... you may want to go parallel to get near 300uf... but that'll just add to your budget. jamato recommended panasonic as being very good filtering caps. or i'd just ask jack what he'd recommend for you to use in place of the blackgates. good luck. *the 6de7 and 6ew7 and not in high demand, which is probably why it's not seen on eebay alot... ask website tube dealers for them and more often than not, they'll have hundreds in stock for $3 to $5 each... i got most of my output tubes at vacuumtubes.net

Hi jamato8/ takezo,

I think I need to bring this up again to ask for some advise in the mod. I have my 6SE mod as mentioned in a thread somewhere i don't remember. The PSU of my 6Se, I've replaced 2 BG VK 150uf/350V and now a BG Heart of Muse 100uf + 100uf/500V (one of my friend told me this big cap is even perform better than NH). I don't notice much changes in sound when I swapped into the Heart of Muse (I have it with about 100+ hrs of burn-in and I know it's still early to make a conclusion), just a bit lighter of bass impact. As you've mentioned above, for the power filtering caps in the PSU, you would suggest to parallel by 2 x 150uf to make it 300uf (because 150uf is insufficient, why?), what make the different between this change, would it be more powerful or impact in the bass level because I thought the bass is very good in a K701 and is it a good move to swap it into 300uf.

This is the LINK of the pics of my modded 6SE. I would be appreciated for an avdise.

Thanks
Danny

 

[cyd2025]

Quote:

Originally Posted by dannie01 /img/forum/go_quote.gif Hi jamato8/ takezo, I think I need to bring this up again to ask for some advise in the mod. I have my 6SE mod as mentioned in a thread somewhere i don't remember. The PSU of my 6Se, I've replaced 2 BG VK 150uf/350V and now a BG Heart of Muse 100uf + 100uf/500V (one of my friend told me this big cap is even perform better than NH). I don't notice much changes in sound when I swapped into the Heart of Muse (I have it with about 100+ hrs of burn-in and I know it's still early to make a conclusion), just a bit lighter of bass impact. As you've mentioned above, for the power filtering caps in the PSU, you would suggest to parallel by 2 x 150uf to make it 300uf (because 150uf is insufficient, why?), what make the different between this change, would it be more powerful or impact in the bass level because I thought the bass is very good in a K701 and is it a good move to swap it into 300uf. This is the LINK of the pics of my modded 6SE. I would be appreciated for an avdise. Thanks Danny

you shouldn't try to influence the bass quality with power filtering caps... not directly...
it's more for filtering out noise and ripple currents... more/better filtering equals overall
better SQ... for bass impact the input/coupling caps will influence how low the freq. will go
and it's quality. but the wa6SE doesn't utilize an input or coupling cap. it's directly coupled
giving the best bass quality the amp can muster. (input caps can roll off the bass or highs
depending on its farad values) but really, let the blackgate caps burn in for at least
700 hrs. before you start modifying it. good luck.

 

[dannie01]

Thanks takezo, I'll take your advise and let see what will it sound after 700hrs reached. BTW, it sounds very nice in the moment and the BGs work wonderful with the 6SE.

 

[cyd2025]

to danny and others interested,

adjusting the cathode resistance seems to really influence the bass quality more than
any other tweaks or upgrades. the 6SE has 3.3k ohms at the cathode on pin 9 but raising
the value up tightens the bass considerably. i think this also allows for impedance matching
to the headphone you would like to voice the amp for.

and it will also have direct ties to the gain of your amp. higher cathode resistance = less gain
and vice-versa. small variance does not affect tonal qualities but larger changes will shift the
tonal balance.

 

[sillysally]

Quote:

Originally Posted by yoff /img/forum/go_quote.gif Thank you ! And what surprises me most with the tube I received is that it does not have mesh-plates but solid-plates (as shown on EML' pictures). It is fantastic anyway !

Yes I found the EML 274B solid plate to be very good, right out of the box. Much better than the SP 274B mesh want to be that was in my WA6SE maxxed.

However I did send my solid plate back for a EML 274B mesh plate.
At first for about 6 hours I was rather disappointed in the mesh plate version compared to the solid plate version. But after about 15 hours using the EML 274B mesh plate it seems to be getting closer to the EML 274B solid plate.

After reading some of jamato8 post, I can understand why It is pointless to ask him. Because of all the mods he has done to his Woo.

ss

 

[regal]

I have a few questions about the topology of the Woo 6. I posted in the other thread but believe those in this thread know more about whats inside.


1. There is mention of upgrading coupling caps. An SET amp doesn't have coupling caps, thats the point of using an air gapped for DC transformer.

2. So does this mean that the Woo 6 is using OPT's that can't pass DC and they are using coupling caps to block the DC?

3. Or are these coupling caps actually interstage caps between each section of the output tube?

4. Wouldn't it be possible to DC couple the two output stages with the right bias?

Confused.

 

[cyd2025]

it's #3. interstage coupling caps. the wa6 implements this, but the wa6SE is direct coupled
and provides dc bias from one stage to the other.

 

[regal]

Quote:

Originally Posted by takezo /img/forum/go_quote.gif it's #3. interstage coupling caps. the wa6 implements this, but the wa6SE is direct coupled and provides dc bias from one stage to the other.

Should be possible to upgrade the WA6 to direct coupled I would think.

 

[cyd2025]

yes, i would think so. of course, the SE also benefits from chokes and a beefier transformer, thanks to a separate ps chassis/space.

 

[regal]

Does anyone have a basic schematic to I could look up the tube curves and find out how to bias for a DC coupling ? Would be worth saving $500 vs the SE.

Debating on buying the WA6 or building this:

I've built a few OTL and hybrid tube amps but never an SET, it almost doesn't pay to build when Woo sells them for less than you can buy parts. I just wish I knew more about the OPT's used on the WA6.