amplifiers audio research D90

pancho montecinos · 26th November 2011, 02:11 AM

hello
please can you help me, I have an audio amplifier research D90 and I need to know if the 4 ohm output is connected to ground, you can switch to 4 ohms speaker? thank you very much regards

speakerfritz · 26th November 2011, 03:35 AM

it looks like it is. here is the schematic. you can confirm by unplugging the amp , disconnecting the speakers...and use an ohm meter between the 4 ohm tap and the chasis...it looks like it will read zero ohms.

asmith · 26th November 2011, 10:43 PM

Audio Research had a worning for many years printed right on the back of the amp that stated that the 4 ohm tap was grounded, not to conect to switching circuts ect.

Zero Cool · 26th November 2011, 10:50 PM

Yes the 4 ohm tap is grounded but the "0" output is NOT! so YES you can use 4 ohm speakers!

kevinkr · 26th November 2011, 11:07 PM

Quote:

Originally Posted by Zero Cool

Yes the 4 ohm tap is grounded but the "0" output is NOT! so YES you can use 4 ohm speakers!

Exactly correct. Noting caveat mentioned in a previous post.

pancho montecinos · 27th November 2011, 11:56 PM

hello thanks, then I can been disconnected on 4 ohm common ground, and use 4 ohm speakers? no problem, would have to adjust bias, or will I have problems with feedback, sorry my question again, Regards

kevinkr · 28th November 2011, 01:01 AM

Quote:

Originally Posted by pancho montecinos

hello thanks, then I can been disconnected on 4 ohm common ground, and use 4 ohm speakers? no problem, would have to adjust bias, or will I have problems with feedback, sorry my question again, Regards

You do not need to, nor should you change any of the connections on the secondary side of your output transformers. All you need to do is connect your speakers between the 0 ohm and 4 ohm taps, that's it..

No bias adjustment is required for use with 4 ohm speakers either.

If you disconnect the 4 ohm tap from ground the amplifier will not operate and will become extremely hazardous as some percentage of the output stage B+ will then appear on the output terminals.

Zero Cool · 28th November 2011, 02:18 AM

I think he is trying to say that he understands not to connect any of the taps to ground. the wording is just not exact.

kevinkr · 28th November 2011, 02:27 AM

Quote:

Originally Posted by Zero Cool

I think he is trying to say that he understands not to connect any of the taps to ground. the wording is just not exact.

I'll keep my fingers crossed and hope that he understands..

26th November 2011, 02:11 AM	#1
pancho montecinos diyAudio Member Join Date: Jun 2010	amplifiers audio research D90 hello please can you help me, I have an audio amplifier research D90 and I need to know if the 4 ohm output is connected to ground, you can switch to 4 ohms speaker? thank you very much regards

26th November 2011, 10:43 PM	#3
asmith diyAudio Member Join Date: Sep 2011	Yes it's grounded Audio Research had a worning for many years printed right on the back of the amp that stated that the 4 ohm tap was grounded, not to conect to switching circuts ect.

26th November 2011, 10:50 PM	#4
Zero Cool Audio Junkie diyAudio Member Join Date: Sep 2004 Location: MN	Yes the 4 ohm tap is grounded but the "0" output is NOT! so YES you can use 4 ohm speakers! __________________ It's not about what you can BUY...It's about what you can BUILD!

27th November 2011, 11:56 PM	#6
pancho montecinos diyAudio Member Join Date: Jun 2010	D90b hello thanks, then I can been disconnected on 4 ohm common ground, and use 4 ohm speakers? no problem, would have to adjust bias, or will I have problems with feedback, sorry my question again, Regards

28th November 2011, 02:18 AM	#8
Zero Cool Audio Junkie diyAudio Member Join Date: Sep 2004 Location: MN	I think he is trying to say that he understands not to connect any of the taps to ground. the wording is just not exact. __________________ It's not about what you can BUY...It's about what you can BUILD!

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