Does Adcom make good Amps ?
- Thread starter braincramp
- Start date
arts
Addicted Member
Never liked speaker fuses myself.Yeah,they work,but it always seemed kinda tacky,if ya know what I mean
Those relay kits are a convenient and inexpensive retrofit.But,they are only really effective when used with mid to lower powered equipment.
When you are dealing with high-powered amplifiers,the elevated rail voltages become the issue.Unfortunately,when a rail-to-output fault occurs,and the sensing circuitry releases the relay, the breaking of the contacts will usually initiate (and sometimes maintain,depending on the amplifier) an arc which will often melt and weld the contacts together,allowing the current to continue,until hopefully something else lets go before the speakers are destroyed.
The problem being that the relay release times are far slower than their latching times,so you don't get a clean,fast break,which allows an arc to initiate.
For all applications above 100 Watts,I always advocate a crowbar circuit.These are easily constructed,and are no more complicated than the relay-based types.The simplest uses a triac across the output terminals.Or, you can do the ''sexier'' version,which has a triac across each rail.
Yeah, I've seen high powered amps weld their relays in one or two cases. It's rare though.
I personally don't care for crowbar circuits. They can greatly add to the damage that needs to be repaired in the event of an output failure, especially if it happens at a high output level, and they can false trip. But that's just me.
I personally don't care for crowbar circuits. They can greatly add to the damage that needs to be repaired in the event of an output failure, especially if it happens at a high output level, and they can false trip. But that's just me.
Cogito
Well-Known Member
I had a GFA-555 II and GFP-555 II for 23 years without a hiccup. Very well made and top-notch performance. The ONLY reason i sold them (Got 65% of my investment back BTW) was simply BECAUSE they were getting old and I was concerned about having to recap and other nonsense.
W9TR
Super Member
Bingo! This exactly describes what happened when my preamp failed and caused my SAE 2600 to go into protection, except the arc from the relay and back emf from the speakers caused the positive side output transistors to fail and dump 105 VDC through the welded contacts into the woofers, which then failed mechanically before the supply fuses in the amps blew. But they were glass fuses, so the vaporized wire coated the inside of the fuse barrels causing them to conduct again, dumping more DC into the woofers. Finally the woofer voice coils opened up. It was very exciting.
The amp was way easier to fix than the speakers. Moral of the story? I don’t worry about relay-based speaker protection anymore. It may save your bacon, then again maybe not. And I have all McIntosh gear with output transformers.
hifitommy
Super Member
i always liked the sound of my 555II and laugh in the face of those who mouth a mantra that adcoms are bright. to that, i say BULLONEY! the 5400 and 5500 are likewise excellent and love to drive martin logans.
i dont have the same admiration for their preamps but the amps are tops. they especially like to be preceded by tube preamps whose lovely sounds are easily passed along to the listener for delightful listening sessions.
i dont have the same admiration for their preamps but the amps are tops. they especially like to be preceded by tube preamps whose lovely sounds are easily passed along to the listener for delightful listening sessions.
david1111
Barba non facit philosophum
@Cogito
I have the GFA 555ii and GFP 555ii at about the same age as well, and the both work great.
The GFA is still my main amplifier, and I'll probably recap it. Eventually tho, I may move up to a used Pass or the like.
@hifitommy
100% agree. There's nothing too bright about my GFA 555ii, (or me, for that matter).
And yes, I find it passes on the sound that's put into it, nicely.
I've traded out my GFP for a tube preamp with Genalex Gold Lion 12ax7 ECC83/B759's in both gain stages, and a Genalex rectifier tube, and it pairs wonderfully with the GFA.
Dave
I have the GFA 555ii and GFP 555ii at about the same age as well, and the both work great.
The GFA is still my main amplifier, and I'll probably recap it. Eventually tho, I may move up to a used Pass or the like.
@hifitommy
100% agree. There's nothing too bright about my GFA 555ii, (or me, for that matter).
And yes, I find it passes on the sound that's put into it, nicely.
I've traded out my GFP for a tube preamp with Genalex Gold Lion 12ax7 ECC83/B759's in both gain stages, and a Genalex rectifier tube, and it pairs wonderfully with the GFA.
Dave
Grainy is the other Adcom amp description I've heard mentioned, a lot. I've never heard one, but my spider sense seemed to indicate most are parroting what is heard online. Would like to hear one someday.
runnin'
Super Member
I never really knew what grainy was until I found it when comparing my flagship OnkyoSR TX876 to an entry level Onkyo TX503 I had picked up on the cheap.
I was quite impressed with how well the 503 did until I noticed this strange character to the sound. The 876 just sounded much smoother at any volume.
In the space of a year I’ve now owned 3 Adcom amps. The 5400, the 6002 and the 555SE. None of them are anything but smooth. And I’ll also say that they put to shame the Emotiva XPA amp I had as well. That amp could get harsh , bright and just unpleasant at about 75+ decibels.
I was quite impressed with how well the 503 did until I noticed this strange character to the sound. The 876 just sounded much smoother at any volume.
In the space of a year I’ve now owned 3 Adcom amps. The 5400, the 6002 and the 555SE. None of them are anything but smooth. And I’ll also say that they put to shame the Emotiva XPA amp I had as well. That amp could get harsh , bright and just unpleasant at about 75+ decibels.
runnin'
Super Member
The grain I heard was with Paradigm tower speakers which have a metal dome tweeter. To be fair it was comparing a $1500 AVR to a $300 one, not exactly fair. It was distinct enough that I never put the smaller avr into the theater system again.
I have never had any electrostats nor heard any.
And to add to my earlier Adcom amp comments, I did another comparison between the little 6002 and the 555SE. While I do like the 6002, the 555 places instruments more precisely and with a touch more realism.
Effortless comes to mind, and with the tons of current standing by, it’s just a pleasure to turn it up!
I have never had any electrostats nor heard any.
And to add to my earlier Adcom amp comments, I did another comparison between the little 6002 and the 555SE. While I do like the 6002, the 555 places instruments more precisely and with a touch more realism.
Effortless comes to mind, and with the tons of current standing by, it’s just a pleasure to turn it up!
SoCal Sam
Lunatic Member
The 555 could have the longest production run of any solid state amplifier. It would be interesting to compare an original Nelson Pass 555 to the latest 555SE.
I'm not arguing with your results, but does the preamp you are using have blocking caps to prevent the pre from passing DC to the amps? That seems like another failure mode that has the possibility of having negative consequences.
SoCal Sam
Lunatic Member
Not sure if we are allowed to post links to other forums but Nelson Pass comments on the 555 in another forum. If you google the thread title "Adcom 555II - Nelson Pass", the result is the first link.
Pio1980
AK Member
I have, so assume it is ok. What's not ok is quarreling over other forums here.
david1111
Barba non facit philosophum
@N8Nagel
I believe that coupling caps are used in a tube preamp, by design. So the focus would then be to ensure that those caps are of good quality and not too old.
With SS preamps, I really don't know if there is a large posibility of a speaker-killing dose of DC leakage happening.
Adcom, Levinson, Pass, and Krell will all amplify DC if it is fed to them. Krell specifically tells us not to use a tube preamp unless the dealer solders some jumpers, to alter the circuit to include coupling caps between the amplification stages. This change, of course, adds complexity to the signal path, which the initial circuit is trying to avoid thru the use of, more passive, DC servos.
Dave
I believe that coupling caps are used in a tube preamp, by design. So the focus would then be to ensure that those caps are of good quality and not too old.
With SS preamps, I really don't know if there is a large posibility of a speaker-killing dose of DC leakage happening.
Adcom, Levinson, Pass, and Krell will all amplify DC if it is fed to them. Krell specifically tells us not to use a tube preamp unless the dealer solders some jumpers, to alter the circuit to include coupling caps between the amplification stages. This change, of course, adds complexity to the signal path, which the initial circuit is trying to avoid thru the use of, more passive, DC servos.
Dave
SoCal Sam
Lunatic Member
Umm, ok. If anything, I was taking the Secretary General of United Nations approach.
Anyways, the guys over there modded the 555 to which Nelson was mostly mum.