Commercial Gainclone kit- building instructions - Page 110 - diyAudio
Go Back   Home > Forums > Commercial Sector > Vendor Forums > Audio Sector

Audio Sector Kits & PC boards from AudioSector

Reply
 
Thread Tools Search this Thread
Old 25th April 2010, 09:56 PM   #1091
Harolda is offline Harolda  Netherlands
diyAudio Member
 
Join Date: Jul 2005
Location: Hoensbroek
Default My gainclone amp is finished, sounds great

Hello all,

i just finished one of my gainclones using Peter Daniels kits. In total i will build two 2 channel amps, each having a bridged LM4780 per channel. I use balanced inputs.
So the first was finished this week, and i will post pictures later. After powering up, i measured the voltage over the loudspeaker outputs and had 0.02 Volts one one channel and 0.023 Volts on the other channel. Than i connected it to my speakers. Nu hum, noise or anything just quiet. Then i connected my preamp and cd-player, still quiet. Then the moment, press the play button, and then there was music. It has been playing now for some hours, and i am starting to like it more and more.
I found my Kenwood/Accuphase L-1000M power amp already very fast and detailed. But this is better. I cannot wait finishing the second amp and using my electronic crossover.

regards
  Reply With Quote
Old 26th April 2010, 07:33 PM   #1092
udailey is offline udailey  United States
diyAudio Member
 
Join Date: Mar 2008
Congrats on your build Haroldo!
Glad you are enjoying it. Now you can start messing around with different caps, beefier power supply, etc Fun stuff isnt it!?
__________________
purchase LDRs anytime Also try my Resistor Replacers or LDR based Input Selector Email me. diyldr@gmail.com
  Reply With Quote
Old 27th April 2010, 01:33 AM   #1093
diyAudio Member
 
Join Date: Jul 2009
I'm building a 4870 kit and have a few questions. I'm new to amplification DIY (and to these higher voltages) but I build low voltage audio electronics (guitar pedals, digital signal processors, synthesizers) professionally.

I'm having trouble figuring out whether I want to build these boards as bridged or parallel amplifiers. I am building this to be a bass guitar amp. I'd like each board to have a single output to a single speaker, and will likely use 8 ohm speakers. I will be driving these with a DIY preamp that's unbalanced.

I'd like to send a single mono signal to both 4870 boards, and have each 4870 driving a single 8 ohm speaker.

Which makes more sense for this setup: bridged or parallel?
  Reply With Quote
Old 27th April 2010, 01:48 AM   #1094
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
If you are using unbalanced preamp it's better to use the amp in parallel mode as bridged amp by itself will not perform unbalanced to balanced conversion. OTOH, with bridged setup you will get more power into 8 ohm than running amp in parallel.

Quote:
Originally Posted by dstebs View Post
I am considering adding a source selector to my LM3875 Premium by installing a DPDT toggle switch ( two sources only). Would there be any point in using a 4 pole DT switch to switch the signal grounds also?

One source will be to a headphone plug to go into a laptop, so SG for both channels will be connected. Will this mess up the star ground? Lastly, would there be an advantage to shorting the signals to ground in this input when it's not in use?
I like to use toggle switches for input selection myself : The most advanced GainClone amp yet

Originally, I was switching grounds too (with a rotary switch though) but later abandoned that and do signal switching only (besides that it's more complicated, you may also get noise when switching grounds)

It's hard to say if it messes up a star ground. If you short the other signal to ground, you should get less crosstalk, but that usually is not a problem.
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 28th April 2010, 09:11 AM   #1095
JL888 is offline JL888  United States
diyAudio Member
 
Join Date: Mar 2010
Location: Dallas, Texas.
Any thoughts on using Vishay Z-Foil for R1, R2 and Rnfb and Vishay VTA55 for R3? The boards look great by the way, thanks Peter.
  Reply With Quote
Old 28th April 2010, 01:07 PM   #1096
tfrei is offline tfrei  United States
diyAudio Member
 
Join Date: Oct 2007
Question on technique:

I really liked your ground star wiring in the post below. Trying to mimic the same in my own build, I had trouble with soldering the copper wire on the back side of the OG pads. The wire from the other side got in the way of a solid resting place for the copper wire. Do you have any technique you can share on this? Do you use a short output ground wire on the opposite side--so it doesn't stick through? Thanks.



Quote:
Originally Posted by Peter Daniel View Post
The important aspect about sharing a single transformer and common rectifiers per two amp channels is power star ground.

While you could simply run PG+ and PG- (ground) wires from rectifier board to each amp board, in some setups hum problems were reported and presently I always use star (power) ground in all my amps.

I simply achieve it by connecting output grounds (OG, on the opposite side of speaker wire connection) with a 14ga solid core copper wire.

The center of that wire is my power star ground and both PG+ and PG- grounds from rectifier board connect here. In the picture below the connections are so short that I used single runs of wire, normally I use two wires for both PG+ and PG-.

Please note that power ground is also directly connected to the chassis.

I specifically refer to it as power star ground, as signal wires from RCAs are not connect directly here. They connect through separate traces on PCB to OG (output ground) pads.
  Reply With Quote
Old 28th April 2010, 01:58 PM   #1097
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
I solder the copper wire directly to output wires on the opposite side of the pads, it's very simple. With Patek, I do it as in attached pic.


Quote:
Originally Posted by JL888 View Post
Any thoughts on using Vishay Z-Foil for R1, R2 and Rnfb and Vishay VTA55 for R3? The boards look great by the way, thanks Peter.
Z-Foil would be certainly very good choice for input series resistors. Caddock MK132 were the best resistors for input shunt and feedback, better than Vishays. As to R3 (680R), Rikens were the best. I use Kiwame now, as Rikens are discontinued. You can try Vishays for that location, but results might not be better.
Attached Images
File Type: jpg pat.jpg (190.6 KB, 633 views)
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 28th April 2010, 02:44 PM   #1098
ss007 is offline ss007  United States
diyAudio Member
 
Join Date: Dec 2009
Peter, I just finished my LM3875 classic test assembly very similar to your build in the first pages of the thread. Only difference is there's a 1/4" chunk of copper between the chips and the bottom of the aluminum channel. And I upgraded the RF to a Caddock MK132. The amp powered up with a DC offset of .049 -.078 on one channel and .05-.036 on the other. Those seem like OK numbers to me. So far I'm very pleased with the sound. I immediately understood what people describe as "fast". I'm also hearing a smoothness in the midrange similar to my old VSP Labs Trans mos 150. Dare I say " tubesque" Thanks so much for the great Customer service.


I do have a couple questions.

1. I left the input series resistor off, using a piece of bare copper. What effect on the sound do people perceive when adding that R?


2. I'm interested in at least listening to the amp with a snubbed PS. I'm taking it that RZ and CZ on the amp board are the zobel. What are the correct values to use?
They also talk about an additional bypass C along with the series R-C snubber network. Where does this C mount and what is the correct value?

Thank you, Scott

Last edited by ss007; 28th April 2010 at 03:04 PM.
  Reply With Quote
Old 28th April 2010, 08:20 PM   #1099
ss007 is offline ss007  United States
diyAudio Member
 
Join Date: Dec 2009
Default pics

pic
Attached Images
File Type: jpg amp.JPG (489.3 KB, 615 views)
  Reply With Quote
Old 28th April 2010, 11:34 PM   #1100
koogar is offline koogar  United Kingdom
diyAudio Member
 
koogar's Avatar
 
Join Date: Mar 2010
Location: West Yorkshire
Hi Limelight

Zobel components

Rz=2R7 and Cz=0.1uF i think


koog
  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
Commercial complete Gainclone kit for a beginner? gychang Chip Amps 365 4th October 2011 08:19 AM


New To Site? Need Help?

All times are GMT. The time now is 08:35 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