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Old 30th March 2006, 01:14 PM   #1
waynev is offline waynev  Canada
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Default 300B amp PS optimization?

I have 300B mono blocks built from a kit but now modifed. Driver is 417A with plate choke, RC coupled to 300B. 300B has DC heaters. Now working on optimizing the power supplies. The supply config is (very small C)-L-C-R-C. Speakers are 100db horns, I hear every little electronics change, I can't beleive the difference I hear in the PS capacitors.

Need some recommendations, of course I'm looking for utopia here but would accept - great tone, NO Listener FATIGUE, reasonable speed, reasonable bass.

I have tried replacing the run-of-the mill electrolytics with ASC oils - ASC oils have wonderfull tone but somewhat slow, no/little space between the music notes, but very relaxing and easy to listen to. Is it possible to design a quicker supply that does use oils caps - how?

I also tried Black Gate WKZ. Great tone, great dynamics, great speed, good bass; but a very slight high end tizzy and high end pressure; its almost an ultrasonic distortion that gets fatiguing after a while. Admittedly mine are not completely broken it yet but the same negative traits exist in run-of-the-mill well used electrolytics and I'm sceptical these negative traits I hear in the BG WKZ will go away after breakin.

Just a thought - but do you think its possible that the because the WKZ are so fast they are passing some high freq junk from other parts of the system/PS through and thats whats causing the high freq tizzy/ pressure/ fatigue?

I have also tried Solen films, they are quick, are not fatigueing but have crappy tone.

So what are options to find the better capacitor setup for my amps. Some thoughts are:

1) Obligatto caps ,Polyprop in oil - any one tried them - what are they like?
2) Ansar film caps - any one tried them - what are they like?
3) Some bypassing arrangement using low value high voltage signal caps in bypass, or those little silver mica caps in bypass?
4) Add a second choke to the PS, redesign PS ??
5) Some combination of the above - I'm open to suggestions

ANy one have and recommendations/ thoughs?


...
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Old 30th March 2006, 02:00 PM   #2
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The ASC's are like Solen films...except they have some oil added into the mix. They should both sound fast.

Remember..that you are probably comparing apples with oranges if you take out a 100uF BG and replace it with say a 50uF ASC.

You have tried some of the very best caps out there. BG, ASC and SOLEN. But you are not happy...?

PS...The faster a cap is the more HF it should filter out...BUT it could cause more noise to be generated as it charges and discharges fiercely if it is a big value.

First I would use PSUD to simulate how your PSU performs. Add a Current sink to simulate the current drawn by your amplifier and add the values you have in your psu. Then go to your current sink and add a stepped load....Value1 is say 20mA and Value 2 is the total current drawn by your amp say...90mA. Use a delay of say 3 ms..Now see if it rings or not.

Then try to do the same simulation for all the values you have had in your amp one time or the other. Try to correlate the ringing with your sound impressions.

Remember friends don't advise other friends to use boutique parts.
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Old 30th March 2006, 02:05 PM   #3
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By the way...I've used ASC and obbligato's in the past but not A/B' ed them...so no comparison here. But purely on a theoretical basis..I'd say they are pretty similar. Both are polypropolyne in oils.

If you don't want to do the PSU simulation route. You should also try paper in oil...(Current production if possible) Because using the NOS ones is apparently a lottery.
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Old 30th March 2006, 05:33 PM   #4
waynev is offline waynev  Canada
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hi Bas

I'm glad you wrote in! I've spent mucho time with PSUD and no ringing/overshoot; however the B+ in PSUD comes up with a rather sharp bend from vertical to horizontal, not a nice arcing section of sin wave I have noticed on other simulations.

So I can easily remedy that by increasing the power trans source R and increasing the first cap slightly. Power trans is a torid.
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Old 30th March 2006, 11:08 PM   #5
arnoldc is offline arnoldc  Philippines
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Quote:
Need some recommendations, of course I'm looking for utopia here but would accept - great tone, NO Listener FATIGUE, reasonable speed, reasonable bass.
wayne, you just described what I want for my amps, but with more speed.

In my 45 amp, I used Audio Professor, which is a dual capacitor. I don't know where to get this Japan-made capacitor, but in the Philippines, my dealer friend sells them.

I have also tried Brian's Obligatto but not critically (via alligator clips, because they don't fit in my chassis ) and they sounded like your description too.

Please take what I said with a bucket of salt.

ps.

The arcing on your PSUD simulation must have been influenced by the impedance of the transformer.
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Old 31st March 2006, 01:39 AM   #6
Jaime is offline Jaime  Uruguay
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Lamm LM2.1 use tube regulated power supply.
Is very interesting !!!!.
best regards
Jaime
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Old 31st March 2006, 01:34 PM   #7
protos is offline protos  Greece
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Yeah, I guess it is time to stop messing with boutique type mods and go for a regulated supply - especially for better bass.
Loesch has described a good one.
Otherwise a true big choke input regulated supply such as the one the canary amps have developed and were available for upgrading for other amps.This seemed to make big differences in speed and dynamics according to reviews in hi-fi+.
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Old 31st March 2006, 02:27 PM   #8
protos is offline protos  Greece
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Sorry, I meant Border Patrol amps not canary.
Look here:
http://www.borderpatrol.co.uk/psuind.htm
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Old 1st April 2006, 04:40 AM   #9
kmtang is offline kmtang  Canada
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I have tried choke input PS. However, the hum ripple is rather high that is not acceptable at all.

In case you prefer employ choke input PS, it is better to use double choke filtering (L-C-L-C) which will eliminate the ripples at B+. The 300B circuitry is more sensitive to hum noise.


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