I'm selling my Amber 3501 analyzer. I used this analyzer quite a bit 4 - 5yrs ago, but I've been using an Audio Precision Sys 1 since then and this Amber just sits around gathering dust any more. I went through this analyzer back about 5yrs ago, the upper analyzer/oscillator pcb had all of the tantalum caps replaced with new 35V rated tant's and the e-caps were also replaced. I also replaced the tant caps with 35v units on the lower input pcb as well. The power supply board on the rear panel received new caps also.
This analyzer didn't come with the freq meter originally. I purchased a used unit off of Ebay that had the freq meter on it and swapped it onto this 3501. The freq meter is very nice to have on these old analyzers because it makes it so much quicker and easier to see what freq you're testing at. I tested the Freq meter back when I installed it to find out what the upper measurement limit of of it was and it will measure freq's up to around 1MHz. Also this analyzer came with the CCIR filter board in it. I wanted the "A wgt" filter so I built one and installed it in the optional filter location. I'll include the CCIR filter board in case you wanted it, but the A-wgt filter is still in place. I picked up a couple of NOS CLM-8500 opto resistors that are used in the tuning section of this analyzer. I installed one of them, I'll include the second one with the purchase. Its still sealed in its original pack.
I added a small cooling fan to the rear panel. I found when using this analyzer for lengthy periods that the covers would get extremely hot. After a few hours of running very hot the analyzer's performance would suffer and the THD readings would rise up from -102 to -103dB up to around - 97dB or so due to the heat. In the early units the power supply was in a separate box, but in the later production models like this one they put the power supply into the main case and eliminated the external power supply. This analyzer has very poor ventilation slots in it and doesn't cool well, when coupled with the internal power supply it gets hot when not actively cooled. Adding the cooling fan completely corrected that situation, this unit now runs at room temp all the time as long as the cooling fan is running.
Also this unit didn't have the battery in it when I got it. I added the wire harness and put a small UPS battery into the unit. I just put a different battery into it a couple of weeks ago that seems to be holding a good charge. I fully charged it and then let the unit sit for 20 min running on the battery and it was still showing about 50% of the "Batt OK" range on the meter. I think you can probably get a good 30min on this small battery without running it down too far. You could put a larger battery in and probably get well over an hour of battery life out of it. This is a great option to have in order to eliminate ground loop issues. Being able to unplug the 3501 from the wall while testing can eliminate a lot of noise issues on gear sensitive to ground loops.
This 3501 has a bit of meter fluctuation when operating and its most visible when operating in the -100dB range. If you run a 1kHz loopback test with the 30khz low pass filter active you'll get .0007 - .0008% THD+N. So the needle fluctuates typically within that range in the -100dB range. Activating the 400Hz HP filter will further drop the 1kHz THD to about .00065 - .00075%. When running a 20kHz loopback test this analyzer will show .00125% THD+N with the 30kHz low pass and 400Hz high pass filters active. Reading that in the -90dB range shows minimal meter fluctuation.
This is a very nice meter that's had most of the maintenance work performed on it and is ready to use.
This 3501 does NOT have the IMD option.
Price $375 + shipping + paypal (I also accept Zelle) I'll only ship to the continental US.
This analyzer didn't come with the freq meter originally. I purchased a used unit off of Ebay that had the freq meter on it and swapped it onto this 3501. The freq meter is very nice to have on these old analyzers because it makes it so much quicker and easier to see what freq you're testing at. I tested the Freq meter back when I installed it to find out what the upper measurement limit of of it was and it will measure freq's up to around 1MHz. Also this analyzer came with the CCIR filter board in it. I wanted the "A wgt" filter so I built one and installed it in the optional filter location. I'll include the CCIR filter board in case you wanted it, but the A-wgt filter is still in place. I picked up a couple of NOS CLM-8500 opto resistors that are used in the tuning section of this analyzer. I installed one of them, I'll include the second one with the purchase. Its still sealed in its original pack.
I added a small cooling fan to the rear panel. I found when using this analyzer for lengthy periods that the covers would get extremely hot. After a few hours of running very hot the analyzer's performance would suffer and the THD readings would rise up from -102 to -103dB up to around - 97dB or so due to the heat. In the early units the power supply was in a separate box, but in the later production models like this one they put the power supply into the main case and eliminated the external power supply. This analyzer has very poor ventilation slots in it and doesn't cool well, when coupled with the internal power supply it gets hot when not actively cooled. Adding the cooling fan completely corrected that situation, this unit now runs at room temp all the time as long as the cooling fan is running.
Also this unit didn't have the battery in it when I got it. I added the wire harness and put a small UPS battery into the unit. I just put a different battery into it a couple of weeks ago that seems to be holding a good charge. I fully charged it and then let the unit sit for 20 min running on the battery and it was still showing about 50% of the "Batt OK" range on the meter. I think you can probably get a good 30min on this small battery without running it down too far. You could put a larger battery in and probably get well over an hour of battery life out of it. This is a great option to have in order to eliminate ground loop issues. Being able to unplug the 3501 from the wall while testing can eliminate a lot of noise issues on gear sensitive to ground loops.
This 3501 has a bit of meter fluctuation when operating and its most visible when operating in the -100dB range. If you run a 1kHz loopback test with the 30khz low pass filter active you'll get .0007 - .0008% THD+N. So the needle fluctuates typically within that range in the -100dB range. Activating the 400Hz HP filter will further drop the 1kHz THD to about .00065 - .00075%. When running a 20kHz loopback test this analyzer will show .00125% THD+N with the 30kHz low pass and 400Hz high pass filters active. Reading that in the -90dB range shows minimal meter fluctuation.
This is a very nice meter that's had most of the maintenance work performed on it and is ready to use.
This 3501 does NOT have the IMD option.
Price $375 + shipping + paypal (I also accept Zelle) I'll only ship to the continental US.
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