hiss

jaudio · 27th February 2005, 01:10 PM

I have a drv134 driving 8 lm3886(4+4)Im getting hiss

each chip has one 220uf and one .1uf on each rail

The chips are inverted with 4k input resistor and 100k feedback resistor

Suggestion needed

carlosfm · 27th February 2005, 05:49 PM

I suppose that's a bridge/parallel arrangement.
You are using too much gain.

jaudio · 27th February 2005, 07:49 PM

Carlosfm:

that was my guess too.

Thanks

jaudio · 27th February 2005, 07:56 PM

Carlosfm:

I would like to use a snubber in my power supply,but the lowest value resistors I have are 2.7ohms. 2.7ohm resistor and a 33nf cap will it work

carlosfm · 27th February 2005, 09:06 PM

Quote:

Originally posted by jaudio
2.7ohm resistor and a 33nf cap will it work

I don't think so.
You need to buy the necessary parts.

carlosfm · 27th February 2005, 09:08 PM

Quote:

Originally posted by jaudio
Carlosfm:
that was my guess too.
Thanks

Change the 4k input resistors for 8.2~10k.

thomas997 · 28th February 2005, 04:39 AM

Do you have any more capacitance than the 220uFs on each chip?

and I hope you have 220uF on both positive and neg rails?

jaudio · 28th February 2005, 10:20 PM

The 220uf caps are on chip rail pins.

I have 136000uf per rail for each monoblock,housed in a separated power supply

macboy · 1st March 2005, 08:38 PM

Reduce the gain! preferably by reducing the size of the feedback resistor, not by increasing the input resistor (smaller resistors make less noise!).

Also try adding a single 0.1 uF or so cap directly across the V+ and V- supply pins of each '3886 (not to ground). Make sure that it is rated at an appropriate voltage (100 V will do).

thomas997 · 1st March 2005, 09:14 PM

Quote:

Originally posted by jaudio
The 220uf caps are on chip rail pins.

I have 136000uf per rail for each monoblock,housed in a separated power supply

nice... just checking.

27th February 2005, 01:10 PM	#1
jaudio diyAudio Member Join Date: Oct 2004	hiss I have a drv134 driving 8 lm3886(4+4)Im getting hiss each chip has one 220uf and one .1uf on each rail The chips are inverted with 4k input resistor and 100k feedback resistor Suggestion needed

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Hiss but no hum...	RockysDad	Tubes / Valves	13	5th April 2009 06:35 PM
Hiss in my P3a Amp	blap0220	Solid State	15	1st June 2007 02:52 AM
SI T-amp - bad hiss in one channel	toolkit	Class D	7	30th November 2006 01:47 AM
Autocostruire t-amp hiss ?	mirland	Class D	29	29th September 2005 08:18 PM
Fullrange hiss ?	mirland	Full Range	14	28th September 2005 12:43 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	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

27th February 2005, 05:49 PM	#2
carlosfm Banned Join Date: Mar 2003 Location: Lisbon, Portugal	I suppose that's a bridge/parallel arrangement. You are using too much gain.

27th February 2005, 07:49 PM	#3
jaudio diyAudio Member Join Date: Oct 2004	Carlosfm: that was my guess too. Thanks

27th February 2005, 07:56 PM	#4
jaudio diyAudio Member Join Date: Oct 2004	Carlosfm: I would like to use a snubber in my power supply,but the lowest value resistors I have are 2.7ohms. 2.7ohm resistor and a 33nf cap will it work

28th February 2005, 04:39 AM	#7
thomas997 diyAudio Member Join Date: Feb 2004 Location: Vancouver	Do you have any more capacitance than the 220uFs on each chip? and I hope you have 220uF on both positive and neg rails?

28th February 2005, 10:20 PM	#8
jaudio diyAudio Member Join Date: Oct 2004	The 220uf caps are on chip rail pins. I have 136000uf per rail for each monoblock,housed in a separated power supply

1st March 2005, 08:38 PM	#9
macboy diyAudio Member Join Date: Oct 2003 Location: Ottawa, Canada	Reduce the gain! preferably by reducing the size of the feedback resistor, not by increasing the input resistor (smaller resistors make less noise!). Also try adding a single 0.1 uF or so cap directly across the V+ and V- supply pins of each '3886 (not to ground). Make sure that it is rated at an appropriate voltage (100 V will do).

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)