Recording Studio Design 800B

[ksrigg]

Probably a dumb question............but here goes.................

How much capitance is enough/ or how much is overkill for a Phase Linear 400 and then for a 700B? I know the 400 came with 75VDC 5,900 uf cap in the power supply, and we are replacing with 15,000 uf for the 400 and 20,000-22,000 uf for the 700B. But how much is needed? When the amps have a transient, or call for the extra power, how deep will it reach for that power? Would the large 35,000 uf caps ever be fully utilized? I know it will take Joe, Lee, Mark or one of you who have the ability to measure such things, but I just wonder, and wonder if ya can HEAR the difference? I know capicators were way more expensive back in the early 70's, and that is the reason the caps were the size they were during their original production...

How much is enough? How far do you chase these larger cans? Just a point of interest....Thanks in advance for any answers, or opinions...

I've always wondered how much is enough..

 

[laatsch55]

Well, the Spec 2 has 88,000 total. A luxman L-85 has 50,000. The Bryston has ?? 40,000?? . 14-20,000 total for the 400 is fine. 30-40 for the 700 is more than adequate. You would have to get close to the factory values with really shitty caps to hear a difference. The power supply in general really has more to do with it than anything. With a marginal power supply no amount of PS caps will make up for it and a well designed power supply is happy witrh 1,000 per 10 volts of rail voltage if they are quality caps.

 

[ksrigg]

I guess the real question is, putting the power supply in a seperate chassis, outside the amp to be large enough to accomadate the HUGE CAPS....is it worth the effort and expense?

 

[laatsch55]

I have yet to see PS droop that can be heard. What you hear more likely is old ,leaky caps failing to filter ripple and sag from ratings going south from age and ineffective electrolyte. The mot difference you'll hear will be fresh caps over old even in the same uf range. And MY opinion of the most change is changing C6 to a 470uf.

 

[laatsch55]

Not if you aren't going to do it anyway.

 

[ksrigg]

Is RIPPLE what makes a cap crappy, or is it just the blowing up and catching on fire part? I bought some Samwha caps from Steve at Apex that I'm starting to wonder about....but I know they had a BAD SERIES...the WB...but beyond THAT series, I haven't been able to find much BAD about them. They are a mojor player for all the mass marketers...I think they are South Korean, but who knows where any given capicator is produced?

 

[laatsch55]

90% in the valley that got tsunamia'd.

 

[laatsch55]

Ripple is AC residuals after rectification to DC.

 

[laatsch55]

NOW!!!!! With all that said,caps can be very subjective, or I should say , cap users can be very subjective , so your mileage may vary.

 

[ksrigg]

I THINK that these Samwha Caps will be fine..they are a different series than the WB bad ones, so I think they'll be just fine. I dound data sheets, and tlink is here:

http://www.samwha.com/electric/product/list_pdf2/HC.pdf


They are CE Series followed by HC....so CE-HC SERIES

 

[Skratch]

Sutton, Read Joe's post on forming PS caps in the PLWO section and use 1,000 - 2000uf per 10 volts of rail voltage and you should not have any problems.

 

[ksrigg]

Thnks Skratch, I'll re-read it. I got most of it, but I couldn't fully understand it. A little over my head...Is it imperative the caps be "formed" prior to useage, or will they eventually "form" from useage? Maybe you make sure the first time you power the amp with the new caps you leave the amp 'ON" for a full 24 hours or something, but, as I said, it's all way above my paygrade...

 

[laatsch55]

Sutton, you already had to send back one example of questionable caps, does 30-40 dollars saved really make that much difference? When you're cleaning up the mess I can tell ya NO!!

 

[laatsch55]

They will eventually form on their own. What Joe is trying to get us to do is to put them in service with known and consistent characteristics, which directly affects service life, and we know how he is about that.

 

[oldphaser]

I started a new thread:
http://forums.phxaudiotape.com/show...enamed-Studiomaster)-800B-vs-Phase-Linear-400

Ed