input sensitivity?

adrianc · 6th March 2008, 08:14 PM

i have been reading the specs on a preamp i have just bought, an adcom gfa750. it states that the output level is 1v. i am getting slightly confused here, my amp is an adcom gfa5802 which has an input sensitivity of 0.1v for 1 wattt and 1.7v per 300watts, does this mean that my amplifier will never reach its maximum performance with on 1v output? could someone please tell me ,if i am figuring this wrongly./

cheers adrian

Jan Dupont · 7th March 2008, 04:29 AM

Yes! You will never get full power as it is now.
Yoou either have to raise the output of the pre (if possible) or lower the sensitivity of the power amp......

adrianc · 7th March 2008, 07:16 AM

thank you for the advise,

i thought as much , that this would be the case.
i have looked at the schematics of the pre amp.(very new to electronics) but i am at a loss of how to increase the output voltage. would anyone know who on here that could point me in the right direction.

would i need to add another amplification stage externally, and just change a resister on the output path.

AndrewT · 7th March 2008, 09:24 AM

Hi,
the output level of 1Vac may be with a standard (but lower) input voltage stated in the specification. The input voltage could be specified as dbU or dbV or something referenced to another standard.

You may find that the maximum input voltage or the maximum output voltage is stated elsewhere and could be considerably higher than 1Vac.

adrianc · 7th March 2008, 01:13 PM

hi andrew

i have checked the output with a multimeter, and it only has a maximum output of 1v? where do i go from here??

sreten · 7th March 2008, 01:39 PM

Hi,

Nominal output of a pre-amplifier is not its clipping level output.
It is highly unlikely your pre-amplifier cannot swing more than
+/- 5V if it needs to, if it is active, probably around +/- 12V.
Multimeters cannot measure peak levels of music waveforms.

/sreten.

adrianc · 7th March 2008, 03:07 PM

i agree my quad 44 has 3 output voltages, the adcom is fixed at 1v max

adrian

sreten · 7th March 2008, 04:37 PM

Hi,

whilst I do not believe output is 1V max, because this implies nominal
output would be <100mV, the easiest "solution" is doubling the gain
of the power amplifier by halving the lower value feedback resistor
of the two feedback resistors that set the power amplifier gain.

/sreten.

adrianc · 7th March 2008, 05:47 PM

sreten

would it be possible for me to email you a schematic , i am only a novice with electronics adrian

AndrewT · 8th March 2008, 10:36 AM

try connecting them together and listen to how it sounds.

6th March 2008, 08:14 PM	#1
adrianc diyAudio Member Join Date: Jan 2008	input sensitivity? i have been reading the specs on a preamp i have just bought, an adcom gfa750. it states that the output level is 1v. i am getting slightly confused here, my amp is an adcom gfa5802 which has an input sensitivity of 0.1v for 1 wattt and 1.7v per 300watts, does this mean that my amplifier will never reach its maximum performance with on 1v output? could someone please tell me ,if i am figuring this wrongly./ cheers adrian

7th March 2008, 04:29 AM	#2
Jan Dupont diyAudio Member Join Date: Apr 2003 Location: Copenhagen, Denmark	Yes! You will never get full power as it is now. Yoou either have to raise the output of the pre (if possible) or lower the sensitivity of the power amp...... __________________ Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com

7th March 2008, 09:24 AM	#4
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, the output level of 1Vac may be with a standard (but lower) input voltage stated in the specification. The input voltage could be specified as dbU or dbV or something referenced to another standard. You may find that the maximum input voltage or the maximum output voltage is stated elsewhere and could be considerably higher than 1Vac. __________________ regards Andrew T.

8th March 2008, 10:36 AM	#10
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	try connecting them together and listen to how it sounds. __________________ regards Andrew T.

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


	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

7th March 2008, 07:16 AM	#3
adrianc diyAudio Member Join Date: Jan 2008	thank you for the advise, i thought as much , that this would be the case. i have looked at the schematics of the pre amp.(very new to electronics) but i am at a loss of how to increase the output voltage. would anyone know who on here that could point me in the right direction. would i need to add another amplification stage externally, and just change a resister on the output path.

7th March 2008, 01:13 PM	#5
adrianc diyAudio Member Join Date: Jan 2008	hi andrew i have checked the output with a multimeter, and it only has a maximum output of 1v? where do i go from here??

7th March 2008, 01:39 PM	#6
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, Nominal output of a pre-amplifier is not its clipping level output. It is highly unlikely your pre-amplifier cannot swing more than +/- 5V if it needs to, if it is active, probably around +/- 12V. Multimeters cannot measure peak levels of music waveforms. /sreten.

7th March 2008, 03:07 PM	#7
adrianc diyAudio Member Join Date: Jan 2008	i agree my quad 44 has 3 output voltages, the adcom is fixed at 1v max adrian

7th March 2008, 04:37 PM	#8
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, whilst I do not believe output is 1V max, because this implies nominal output would be <100mV, the easiest "solution" is doubling the gain of the power amplifier by halving the lower value feedback resistor of the two feedback resistors that set the power amplifier gain. /sreten.

7th March 2008, 05:47 PM	#9
adrianc diyAudio Member Join Date: Jan 2008	sreten would it be possible for me to email you a schematic , i am only a novice with electronics adrian

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

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
BJT input dv/dt sensitivity	zilog	Class D	0	18th January 2006 07:31 AM
Son Of Zen Input Sensitivity	rutcho	Pass Labs	3	30th November 2003 03:46 PM
BOZ input sensitivity	gema	Pass Labs	0	29th July 2002 10:55 AM
input sensitivity [SoZ]	Phage	Pass Labs	2	21st January 2002 04:07 AM
Input Sensitivity	StefanJ83	Everything Else	1	20th November 2001 10:17 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