Help Improve Parts Express Plate Amp - Page 2 - diyAudio
Go Back   Home > Forums > Loudspeakers > Subwoofers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 30th January 2009, 05:42 AM   #11
diyAudio Member
 
Moondog55's Avatar
 
Join Date: Jun 2007
Location: Norlane; Geelong: Victoria: Australia
Some-one else better tell you if it'd feasible or not but, I think a little P2P wiring and a heat sink mounting for a new/bigger bridge rectifier is possible.
BTW that same amp ( or a clone ) is for sale here at $350AUD do you feel better now??
__________________
QUOTE" The more I know, the more I know, I know (insert maniacal laugh >here<) NOTHING"
  Reply With Quote
Old 30th January 2009, 10:50 AM   #12
tinitus is offline tinitus  Europe
diyAudio Moderator R.I.P.
 
Join Date: Nov 2005
If it works dont fix it

Joke aside, as long as it works properly you wont hear any difference from changing a few parts, unless you are a real wizzard with amps
__________________
sometimes we know very little, and sometimes we know too much
  Reply With Quote
Old 30th January 2009, 10:51 AM   #13
diyAudio Member
 
Moondog55's Avatar
 
Join Date: Jun 2007
Location: Norlane; Geelong: Victoria: Australia
OK Tinitus; that is good advice,
__________________
QUOTE" The more I know, the more I know, I know (insert maniacal laugh >here<) NOTHING"
  Reply With Quote
Old 30th January 2009, 10:57 AM   #14
tinitus is offline tinitus  Europe
diyAudio Moderator R.I.P.
 
Join Date: Nov 2005
Thanks

Sounds like the reason fore asking this is concerns about sub control and power
If so its more likely due to speaker design, placement or room issues or maybe coherence problems between sub and mains
__________________
sometimes we know very little, and sometimes we know too much
  Reply With Quote
Old 30th January 2009, 06:38 PM   #15
clm811 is offline clm811  United States
diyAudio Member
 
clm811's Avatar
 
Join Date: May 2002
Location: Northern California
Quote:
Sounds like the reason fore asking this is concerns about sub control and power
Yes. I think I've done everything I can over the last 5 years regarding placement(moving it, measuring with test tones and SPL meter, crawling around the floor, etc), plus many frequency/phase adjustments.

The woofer itself is a tried and proven design that has garnered many good reviews over many years. When powered by another, my main amplifier(Parasound), the bass is taughter and is more dynamic sounding; Therefore, I find the plate amplifier suspect(I've tried it with and without bass boost).

Everything I've read (esp. here on DIYaudio) about SS amplifier design indicates a need for adequate power supply capacitance for sufficient current delivery to control a woofer system- most bass amps utilizing 20mf, 40mf or more in PS capacitance.

Amp design guru John Curl wrote:
Quote:
"We have found that 20,000 uF and more is necessary, per channel, to make the bass sound right."
.

I was just concerned about the practical limits of this particular circuit. I am assuming that the 6,800uf caps in this amp were chosen for economy, not performance.

Since I'm not that familiar with "plate" amps for subs, I'd hoped someone here on the "Subwoofer" forum might have all the answers.

I will turn to the SS amplifier forum to see what answers I can get.

Thanks to all here for your efforts!
  Reply With Quote
Old 12th July 2010, 05:56 PM   #16
clm811 is offline clm811  United States
diyAudio Member
 
clm811's Avatar
 
Join Date: May 2002
Location: Northern California
Default HELP!- PS Caps get HOT! Fuse blows

I finally got around to testing the plate amp, and upon powering it up, the
4A line fuse blew. I touched the two "Jun Fu" 6800uf electrolytic caps and they felt unusually warm for such a short power-up.

To be sure it wasn't just a turn-on surge, I slowly powered it up through a variac. The fuse didn't blow this time, but the caps felt
very hot !

Looks like I'll have to replace them anyway, after all.

Anyone else have this experience with these caps?

Recommendations?

-Chas

p.s. I tried to contact Steve at Apex Jr., regarding the Jun Fu caps(he sells these), but he's away on vacation for another week.
  Reply With Quote
Old 12th July 2010, 06:27 PM   #17
diyAudio Member
 
chris661's Avatar
 
Join Date: Feb 2008
Location: Sheffield
Blog Entries: 8
I tend to find 10,000uF caps are a reasonable compromise between value and price.

WRT the rectifier - in a recent rebuild, I did what MoonDog mentioned, ie, mounting it on the heatsink, with a few bits of wire. It gives a much greater choice of rectifiers, too.

I'm sure I've just replied to that post, but here goes...
Hot caps are an indication of something wrong, so maybe check positive/negative rails and stuff. And the voltage of the output of the rectifier. If that's above the voltage rating of the caps, you need to keep it switched off. Over-voltage on caps can explode them.
__________________
"Throwing parts at a failure is like throwing sponges at a rainstorm." - Enzo
My setup: http://www.diyaudio.com/forums/multi...tang-band.html
  Reply With Quote
Old 12th July 2010, 07:15 PM   #18
clm811 is offline clm811  United States
diyAudio Member
 
clm811's Avatar
 
Join Date: May 2002
Location: Northern California
Default Caps Rattle when shaken

I removed the suspect caps and upon shaking them they rattle as if there is something loose inside. Other electrolytics on hand do not exhibit this.

Shall I assume they have "dried-out" and that's why they are bad?

I'm now shopping for some good quality 80V snap-ins...

-Chas
  Reply With Quote
Old 12th July 2010, 08:19 PM   #19
Khron is offline Khron  Romania
diyAudio Member
 
Join Date: Jul 2005
Location: Finland
Send a message via AIM to Khron Send a message via MSN to Khron Send a message via Yahoo to Khron
"Jun Fu" are only one of the (too) many brands of "crap caps". If you'd like to also make sure your plate amp will have a long, reliable life, i'd recomment you went for replacement from one of the (few) reputed brands (Panasonic/Matsushita, Rubycon, United Chemicon, Elna, Nichicon, Samxon).
  Reply With Quote
Old 13th July 2010, 11:00 PM   #20
clm811 is offline clm811  United States
diyAudio Member
 
clm811's Avatar
 
Join Date: May 2002
Location: Northern California
Default New larger caps work fine

OK

I replaced the two bad 6,800/80v caps with a pair of Cornell Dubilier 15,000uf/80v caps, and the amp works great!

Thanks for all the help.

-Chas
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
FS: Parts Express 250watt plate amp jin5 Swap Meet 3 14th March 2008 04:36 AM
FS ... Parts express 250 watt plate amp ... jhammer221 Swap Meet 3 24th March 2006 01:34 PM
parts express ! onis_uk Multi-Way 9 7th August 2004 01:56 AM


New To Site? Need Help?

All times are GMT. The time now is 06:47 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2