Wwoderfull story.
Adcom Amp Owners Rejoice!
If you have an Adcom amp in the 535 or 555 series and you somehow manage to trip the Thermal Protection indicator, don't despair. Unless you have been seriously over-driving the amp, you may be able to solve the problem yourself. I stupidly tried to make a speaker cable change or adjustment a few months ago, and the amp died, tripping the TP indicator. I went online and found that in many instances, an internal fuse (there are generally 4 of them) could be blown. I ordered some 4 amp fuses from Amazon (a financial mistake); they arrived a few days later and I took the top cover off of the amp to install as many as needed. First thing I learned is that you need a fuse puller to remove a fuse. Went to the local NAPA store and got a cheap one for less than $4. The first fuse I pulled was blown, but the other three were fine, and I took that as a good sign. Installed a new fuse, plugged the amp in and hit the power button....it came on as normal and I breathed a sigh of relief. I haven't actually tried to use it yet, but expect no further problems. About one year ago, I had a similar problem with my GFA-555ii amp, and paid $140 to a repair shop to get it fixed. I have no doubt that was nothing more than a blown fuse, so a valuable lesson was learned there.
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They definitely are - I have three of them (GFA 555ii / 535ii / 7500), and they are all workhorses. The amp was not at fault....I had it hooked to a multi-speaker switch and tried to swap out a set of cables on the switch while the amp was on. I think that caused a short that threw the amp into the Protect mode. I considered it as punishment for violating the "Don't make any connections/disconnections while the amplifier is on" rule. |
@discnik You have a repair shop? Wow! Nothing doing here in N Cal. |
Although not in use, I own 3 535 series II, which I feel are the best of the Adcom amps, to my ears, in my system. It is a far superior performing/sounding amp than the original 535, eliminating the speaker switching and those silly speaker cable connectors, along with some circuit changes too. @panzrwagn the 535s and 545s are not MOSFET amps, they use BJTs. My best, MrD. |
@mrdecibel . Nope. In the mid 1980s, Pass designed the well-reviewed Adcom GFA-555 amplifier. This was a Bipolar Junction Transistor (BJT) based design. Nelson also designed the GFA-5XXX MOSFET-based series of high-bias class-AB amplifiers for Adcom (i.e. -5300, -5400, -5500, -5800). I got introduced to MOSFET amps in 1975 via Sony's TA3650 integrated. We used it to drive ADS L400 and the original M&K passive subwoofer. Wouldn't play that loud, but it was stunning at reasonable levels. This was in 1975. |
@panzrwagn Yes, I know all of the Adcom amps and the others designed by Nelson. The models you mentioned that are running your theater are not MOSFET. That was my point. I am most familiar with the VFETS in Sony designs. My best, MrD. |
in the mid 1990's I bought several Adcom amps on eBay for "distributed whole house system". a system in every room. One of those 535 has been powered on in either my garage or basement for over 25 years! Also owned the 5400, 545ii, still running a 7300 for LCR. the 5400 was eventually bested by a 200w Rotel . |
Coinkydink! I just picked up a NAD 1155 this week on A'gon. Paired it with a NAD 4150 tuner, also bought at the same time, and my GFA-535ii (to test it out after the fuse replacement that started this thread). Even using an ancient pair of Realistic Minimus 2.5 speakers (one 4-inch driver each) couldn't make the combo sound bad, mainly because I also had a sub connected via the 1155's second set of outputs. The highs were just so-so, but the midrange sounded pretty darn good, all things considered. |