impedance mismatch?

Jimmy D. · 16th December 2004, 06:00 PM

I recently finished a GC using Brian's kit. I'm impressed initially with the sound but last night I replaced an AVA mosfet 100w/chan (old Dynaco ST150) with the gainclone and noticed not so good bass performance. The application is a bi-amplified speaker system using a S&B TX102 TVC driving an active xover. Signal below 200 hz is sent to the GC (or mosfet amp) for bass duties. Speakers are big Altec 515s. What I'm hearing...... the mosfet amp gives tighter more tuneful bass performance. The GC is a little uncontrolled and tubby sounding. Bass notes seem to all run together.

Any idea how to analyze this problem to see if it is an impedance issue?

Jim D.

Bill Fitzpatrick · 16th December 2004, 06:13 PM

As I recall, GC builders use more supply capacitance when the amp is confined to bass duties. Try 10,000 mfd.

demogorgon · 16th December 2004, 08:23 PM

lots of capacitans and a snubber should do the job. 2*1500uf on chip is nothing near enough for bass, and not enough for anything else either, or at least so i think, having compared 2*1000uf per board, 2*1000uf per board+2670uf per rail in the PS, 2*1000 per board+6200 in the PS, and finally, and what i ended up using, 2*1000uf per board+ 6200uf per rail en the PS with a snubber. read carlosfm's post about the big capacitans psu for chipamps. it's on the first page.

regards
marius

16th December 2004, 06:00 PM	#1
Jimmy D. diyAudio Member Join Date: Oct 2004 Location: Southeast US	impedance mismatch? I recently finished a GC using Brian's kit. I'm impressed initially with the sound but last night I replaced an AVA mosfet 100w/chan (old Dynaco ST150) with the gainclone and noticed not so good bass performance. The application is a bi-amplified speaker system using a S&B TX102 TVC driving an active xover. Signal below 200 hz is sent to the GC (or mosfet amp) for bass duties. Speakers are big Altec 515s. What I'm hearing...... the mosfet amp gives tighter more tuneful bass performance. The GC is a little uncontrolled and tubby sounding. Bass notes seem to all run together. Any idea how to analyze this problem to see if it is an impedance issue? Jim D.

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
impedance mismatch	ddoyle	Multi-Way	6	17th January 2008 04:06 PM
INA134 and input impedance mismatch	redrabbit	Solid State	20	30th September 2007 09:38 AM
Impedance Mismatch	sushizen	Full Range	1	16th November 2006 01:18 PM
impedance mismatch headaches.	xstephanx	Multi-Way	11	10th April 2006 07:36 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

16th December 2004, 06:13 PM	#2
Bill Fitzpatrick diyAudio Member Join Date: Jun 2001 Location: Eugene, OR	As I recall, GC builders use more supply capacitance when the amp is confined to bass duties. Try 10,000 mfd.

16th December 2004, 08:23 PM	#3
demogorgon diyAudio Member Join Date: Jul 2004 Location: Behind you.	lots of capacitans and a snubber should do the job. 21500uf on chip is nothing near enough for bass, and not enough for anything else either, or at least so i think, having compared 21000uf per board, 21000uf per board+2670uf per rail in the PS, 21000 per board+6200 in the PS, and finally, and what i ended up using, 2*1000uf per board+ 6200uf per rail en the PS with a snubber. read carlosfm's post about the big capacitans psu for chipamps. it's on the first page. regards marius

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