Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Chip Amps Amplifiers based on integrated circuits

This is not just another gainclone
This is not just another gainclone
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 13th February 2003, 06:10 AM   #691
JDeV is offline JDeV  United Kingdom
diyAudio Member
 
Join Date: Oct 2002
Location: Hemel Hempstead
Thanx for the effort Dave
I measured the output yesterday by connecting a fat 8ohm resistor and applying a 200Hz sine wave. It started to clip at 10.6v Trms. Now if I calculate correct:

Pout=V/R
=10.6
--------
8
=14 Watt

What do I miss?
  Reply With Quote
Old 13th February 2003, 06:38 AM   #692
2002tii is offline 2002tii  Norway
diyAudio Member
 
Join Date: Apr 2002
Location: Norway
Peter D. has mentioned that his 18V supply sounds better than his 24V.

Can the reason be that the chip is "linear" up to around +/-28V dc, so when you (like I do) use 24V trafo`s the output power in 4 and 6ohms decrease.

By the graph it looks like my GC (running +/-36V dc) puts out around 60W in 8ohm, 12W in 6ohm and <10W in 4ohhm...

It looks like the chip behaves more like an ordinary amp. as long as the voltage is below +/-28V dc.

Just a tought....
__________________
Regards Dan M.
  Reply With Quote
Old 13th February 2003, 06:53 AM   #693
Steve Eddy is offline Steve Eddy  United States
diyAudio Member
 
Steve Eddy's Avatar
 
Join Date: Sep 2002
Location: Sacramento, CA
Quote:
Originally posted by JDeV
Thanx for the effort Dave
I measured the output yesterday by connecting a fat 8ohm resistor and applying a 200Hz sine wave. It started to clip at 10.6v Trms. Now if I calculate correct:

Pout=V/R
=10.6
--------
8
=14 Watt

What do I miss?
Your math's fine.

The 22 volts you mentioned previously that you measured on the rails, was that the unloaded voltage? And are you using just 1,000 uF of filter capacitance?

Be aware that under load your transformer's voltage will be less than the unloaded voltage. What's the regulation figure for the transformer you're using? Also, if you're using just 1,000 uF of filter capacitance that those caps are going to be drawn down quite a bit between refresh cycles so your average power supply voltage will be less as well. Both instances mean that your amp will start to clip sooner compared to what you would expect basing your expectations on the unloaded rail voltages.

se
  Reply With Quote
Old 13th February 2003, 08:13 AM   #694
JDeV is offline JDeV  United Kingdom
diyAudio Member
 
Join Date: Oct 2002
Location: Hemel Hempstead
Quote:
Originally posted by Steve Eddy


Your math's fine.

The 22 volts you mentioned previously that you measured on the rails, was that the unloaded voltage? And are you using just 1,000 uF of filter capacitance?

se

Indeed, 22V on rails while unloaded and only 1,000uF. I plan to fit a pair of 10,000uF and also some other PSU improvements once current setup burnt in, to be able to do reasonable comparison between "before" and "after."
  Reply With Quote
Old 13th February 2003, 08:48 AM   #695
planet10 is offline planet10  Canada
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
This is not just another gainclone
Quote:
Originally posted by 2002tii
Peter D. has mentioned that his 18V supply sounds better than his 24V.
....
Can the reason be that the chip is &quot;linear&quot; up to around +/-28V dc, so when you (like I do) use 24V trafo`s the output power in 4 and 6ohms decrease.
This is what my recommendation of 18-0-18 trafos is based on.

dave

planet10/whose chips are still in their anti-static bags
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 15th February 2003, 01:10 AM   #696
Peter Daniel is offline Peter Daniel  Canada
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
This is not just another gainclone Send a message via AIM to Peter Daniel
Quote:
Originally posted by 2002tii
Peter D. has mentioned that his 18V supply sounds better than his 24V.

I did not say it sounds better with lower voltage. I said it produces more bass. Depending on the rest of the system, it may change the tonal balance and be actually something unwanted. The person who is using my first gainclone, said that he prefers the sound of the higher voltage supply, which is using Plitron 400VA , 22-0-22 V transformer. This transformer is so powerfull that I actually see 24 V all the time because of regulation factor, which doesn't apply here.
__________________
To order kits contact me through forum mail.
  Reply With Quote
Old 15th February 2003, 07:23 AM   #697
coffin is offline coffin  Taiwan
diyAudio Member
 
coffin's Avatar
 
Join Date: Oct 2002
Location: Taiwan
Hi,
There's a paralell version schma.
Check this
http://www.fortunecity.com/underworl.../lm3875x4d.jpg
cheers

Coffin
Attached Images
File Type: jpg lm3875x4.jpg (35.1 KB, 1690 views)
__________________
Ignorance and self-centered are the epidemics of human.
  Reply With Quote
Old 16th February 2003, 07:05 PM   #698
Mats J is offline Mats J  United States
diyAudio Member
 
Join Date: Aug 2002
Location: Seattle
If you take four(4) inverted GC's, parallel pairs (so you then have two amps), remove the pots and feed each parallel pair with a phase from a Jensen Transformer model JT-10KB-D. Would that work as kind of a BPA-200/High power GC?
  Reply With Quote
Old 16th February 2003, 07:20 PM   #699
Steve Eddy is offline Steve Eddy  United States
diyAudio Member
 
Steve Eddy's Avatar
 
Join Date: Sep 2002
Location: Sacramento, CA
Quote:
Originally posted by Mats J
If you take four(4) inverted GC's, parallel pairs (so you then have two amps), remove the pots and feed each parallel pair with a phase from a Jensen Transformer model JT-10KB-D. Would that work as kind of a BPA-200/High power GC?
Basically, yes. But why use a 4:1 stepdown transformer? Just use an 11P-1. You'll need to use a pair of 5k resistors in series across the output taking your ground reference from the node between the two resistors.

se
  Reply With Quote
Old 18th February 2003, 07:40 PM   #700
2Bak is offline 2Bak  Denmark
diyAudio Member
 
Join Date: Apr 2002
Peter Daniel,
what kind of power plugs do you use here?
http://www.diyaudio.com/forums/showt...281#post104281

Would it not be good idea to use XLR's for power?
  Reply With Quote

Reply


This is not just another gaincloneHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Freebird + Gainclone = "integrated" gainclone? bikehorn Chip Amps 9 5th January 2006 03:07 PM
JLH v Gainclone? Jezz-the-Fezz Solid State 5 12th December 2005 12:08 PM
Big gainclone steven344 Chip Amps 10 23rd November 2005 07:58 PM


New To Site? Need Help?

All times are GMT. The time now is 11:43 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki