Commercial complete Gainclone kit for a beginner? - Page 37 - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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 4th June 2008, 07:05 PM   #361
diyAudio Member
 
danielwritesbac's Avatar
 
Join Date: Nov 2007
The carlosfm 2005 power supply schematic does have a "rails to rails" component.

On the output end (amplifier end) of his power schematic, and according to the sidenotes, there's a single poly type capacitor of 3.3uF or 4.7uF. Naturally, it would have 100v or greater tolerance/capacity. That optional cap is a "sink the mids" arrangement for LM3875 and LM3886 amplifiers. Such voicings are somewhat "component specific," and I wasn't able to obtain the make and model number of the cap used in his studies.

Refer to the carlosfm power supply thread(s) for more information on that optional component.

My simplified power supply schematic in the post above, is capable of supporting that optional component to its intended effect.

Instead. . . A very similar voicing/effect is seen on the audiosector power boards as that pair of small value blackgate electrolytic caps (on the power board itself).

Or skip it, because (in my opinion) a "sink the mids" arrangement is unnecessary for LM1875. I think its midrange is quite pleasant without an "effect."

Or skip it, because you specify a very short cable between the amplifier and power supply. I think that's easier to do on a monobloc or dual mono style.
  Reply With Quote
Old 14th November 2008, 02:12 PM   #362
diyAudio Member
 
Join Date: Nov 2008
Can I really hear the difference between the Premium LM3875 and Classic LM3875 Kit?
I mean, they are the same but use different (pricy) components.

And what about their PCB used with "common" components? Would such a version be a bad expierence?
  Reply With Quote
Old 14th November 2008, 11:03 PM   #363
diyAudio Member
 
danielwritesbac's Avatar
 
Join Date: Nov 2007
Quote:
Originally posted by bestbier
Can I really hear the difference between the Premium LM3875 and Classic LM3875 Kit?
I mean, they are the same but use different (pricy) components.

And what about their PCB used with "common" components? Would such a version be a bad expierence?
A low-component-count design that achieves hi-fi, usually does so because of careful component choices to combat the poor tolerances design. So, the answer to all of your questions is probably "yes," although that is not guaranteed.

Once again, the concept is that the low-component-count amplifier is highly reliant on component choices, and thats why the selection gets more difficult; so, it is "technically" a poor design choice, until it works.

The Audiosector product is a "known good" and the difficult research has already been done for you, so you know that your purchase will perform very well. Basically, either you can gamble, or you can Audiosector. And, Audiosector's premium kit is less expensive than a gamble. Do use exactly the recommended transformer and impedance matcher controls too, else you will have constructed a much different amplifier.

What kind of gamble to do it some other way? Well, have a look at LM3875.pdf and notice that noise rises with frequency. Take into account audiology studies, and you'll find that random choices with LM3875 is not likely to be a pleasant presentation, but rather is like playing music over a siren.

Instead of making a noise, use a "known good" design along with well-tested components. That will be considerably less expensive.
  Reply With Quote
Old 5th September 2011, 04:06 AM   #364
diyAudio Member
 
Join Date: Sep 2011
Location: Kansas City, MO
Hey everyone, I'm just kinda curious. Can I sufficiently use a 3X3X3 inch heat sink w/ cooling fan attatched? Unfortunately I do not have the specs on the heatsink to figure out the dissipation. However, does the idea sound within reason?
  Reply With Quote
Old 5th September 2011, 08:30 AM   #365
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
fan noise !
__________________
regards Andrew T.
  Reply With Quote
Old 4th October 2011, 08:19 AM   #366
diyAudio Member
 
danielwritesbac's Avatar
 
Join Date: Nov 2007
Quote:
Originally Posted by CorySCline View Post
Hey everyone, I'm just kinda curious. Can I sufficiently use a 3X3X3 inch heat sink w/ cooling fan attatched? Unfortunately I do not have the specs on the heatsink to figure out the dissipation. However, does the idea sound within reason?
Omit the fan. 3x3x3 inches of heatsink can run LM1875 stereo pair if given good stable design and 8 ohm speakers. Amplifier enclosure needs air intake vent under heatsink and air output vent near top of enclosure. Hot air will voluntarily, quietly, get out of the amplifier that way. This is near maximum--add some metal brackets to the heatsink.

That heatsink can also run Inverting LM3875 (see Decibel Dungeon) and it can run non-inverting TDA7294, both using very slightly lower voltage, snubbed rectifier, and 8 ohm speakers. One heatsink of that description per each chip, plus appropriate cool air inlet and hot air outlet in the amplifier enclosure. This is also near maximum, add some metal brackets to the two heatsinks.

For supporting your recycled computer heatsink with other, hotter, amplifier options, you can bolt and bond together 4 of the 3x3x3 inch heatsink with bulk aluminum rails from the hardware store to create one larger heatsink.


I'm 39 now. Man, this is an old thread!


As far as gainclone design goes, the necessarily exacting specifications for achieving useful results. . . never include adding a broadcast of noise at point blank range to a receiver.
  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
Complete beginner - Need Help Metalcore322 Solid State 3 31st March 2009 03:52 PM
Complete beginner; looking to start. kartoffel Solid State 4 11th October 2004 08:20 AM


New To Site? Need Help?

All times are GMT. The time now is 09:38 PM.


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