Krell vs Adcom

[Infinity!]

Hey guys, I am needing some input as to how these two ampliers compare. The amps I currently own are Adcom GFA 565's and I am looking at getting a Krell KSA 300s. I already know the krell is going to win in bass, I have no doubt about that! My question lies with how the highs and mids sound on the krell. I know Krell is not known for being a warm sounding amp, however, would the 300s be more musical compared to the 565's? What are your thoughts and/or experiences? Thanks!

 

[bhunter]

As you know, the Krell is a much better amplifier both in build and sound. In fact, given your Infinity Kappa 9s, it would be ideal. There really is no comparison IMHO. There are only a few SS amps I'd take over a Krell, namely, Boulder and Pass Labs.

 

[tarior]

I'd call Krell and find out if they still offer any kind of support for those amps, as Krell is factory service only. Many "high-end" manufacturers don't release service docs, and also don't support legacy gear. There are few things worse in the audio world than owning a 185lb. door stop.
Adcom service and support is excellent.
So far as comparing sound, there is only one way to find out which one will sound better in your room, with your speakers.

 

[Ds2000]

Just make sure the Krell has seen a service of the mains caps and a full checkup otherwise before you buy. It’s about 23 years old now.

 

[tarior]

I suspect that if the Adcoms are functional, they had the driver boards rebuilt. That was one of the models that suffered from the supplier delivering a batch of faulty capacitors.
My GFA-585 had that issue as well. Adcom was very helpful with giving the part #s for the op-amps and voltage references needed to get it back up and running.

 

[tarior]

Maybe. But if it can't be repaired if (when) it fails, it's pretty much junk.

 

[Sound Dragon]

Krell still services most of their older legacy Amps. The KSA and FPB's are still in many homes being enjoyed. Be advised that they are not cheap to service and while I am sure a competent tech could do the work for less, would you really want too? Being that they run in Class A or A-B and thus generate a fair amount of heat, they will need to be looked at some point. Who better than the folks who work on them every day. I recently bought a KSA 250 and am running it without any issue with Infinity RSII's. It will, however, be going to Krell in a few months to get a full factory refresh just for my own peace of mind.

 

[tarior]

Same with the Adcom, and the Adcom doesn't have a protection circuit so when it goes, it will take the speakers with it.

The Adcom can be repaired. Full service documentation is available, and Adcom will help with parts substitutions.
If one is concerned with an amp going into DC, he can always fuse his speakers, or install an aftermarket DC detector/relay board.
BTW, the Adcom specs a whole lot better than the Krell.

 

[Sound Dragon]

The Adcom can be repaired. Full service documentation is available, and Adcom will help with parts substitutions.
If one is concerned with an amp going into DC, he can always fuse his speakers, or install an aftermarket DC detector/relay board.
BTW, the Adcom specs a whole lot better than the Krell.

Having owned an Adcom in my journeys past, and now a Krell. I can honestly say that there is just no comparison to the way these amps sound. The Adcom just does not compete with the Krell on any level except for its price.

 

[tarior]

Well, there we have it. The high dollar gear that doesn't spec well always sounds better.

 

[nyhifihead]

Krell by far...

If nelson pass is the reason you are interested in the adcom then check out threshold, perhaps a s300, watt for watt threshold will be a little less money than krell but expect the class A or mono thresholds to be as much as a krell on 2nd hand market

And same scenario as mentioned before, class a, a/b for a 20+ yeah unit will need some sort of bill of health and recap. Threshold repair is also much more available and probably cheaper.

Also worth mentioning the nak pa-7.

 

[Sound Dragon]

Well, there we have it. The high dollar gear that doesn't spec well always sounds better.

Glad we agree!

Krell by far...

If nelson pass is the reason you are interested in the adcom then check out threshold, perhaps a s300, watt for watt threshold will be a little less money than krell but expect the class A or mono thresholds to be as much as a krell on 2nd hand market

And same scenario as mentioned before, class a, a/b for a 20+ yeah unit will need some sort of bill of health and recap. Threshold repair is also much more available and probably cheaper.

Also worth mentioning the nak pa-7.

The Nak PA 7's are great amps but also getting up there in the purchase price. I think the Cats out of the bag with Nak units and gone are the days when you could get Threshold sound on a lower budget. Threshold is an excellent recommendation and probably cheaper to service than a Krell. But I doubt that the savings will be much. The op would be well served with either of these amps. But I will say that the Krell I own is a very musical amp and while I too feared that it would be very analytical in sound, it just isn't that at all.

 

[tarior]

You can have Krell repaired also, just not by yourself. Adcom specs do not tell the whole story. They are not that good. To me they are grainy.

Unlike many here, I am a trained tech. I flat out will not touch any piece of gear that doesn't have full service documentation.
As far as I'm concerned, a company that sells amplifiers/preamps/etc. that won't publish full specifications and full service documentation is trying to hide something.
I won't in good conscience ever recommend equipment made by an outfit like that. Ever.
In the case of sounding "grainy". I don't even know what to tell you there.

 

[Tedrick]

Krell by far...

If nelson pass is the reason you are interested in the adcom then check out threshold, perhaps a s300, watt for watt threshold will be a little less money than krell but expect the class A or mono thresholds to be as much as a krell on 2nd hand market

And same scenario as mentioned before, class a, a/b for a 20+ yeah unit will need some sort of bill of health and recap. Threshold repair is also much more available and probably cheaper.

Also worth mentioning the nak pa-7.

Or if you want newer, check out the Usher 1.5. It's essentially a very slightly modified authorized copy of a Threshold S/300. Sounds amazing, too.

 

[llwhtt]

I had the privilege of repairing three Krells not too long ago, two KSA100MKII and a KMA100MKII. All I can say is WOW what amplifiers they are. Easy to work on, wwwwwwaaaaaayyyyyyy over built, and good sounding. They do run hot though, my repair was mainly replacing the roasted output transistors but the customer wanted the small electroytics replaced as well. Other than the power supply filter capacitors there are only two electrolytics in the signal path and they are in the feedback loop, the rest of the electrolytics are in the output relay circuit. If I had the choice I would pick the Krells, comparing the Krells to the Adcom is just not fair, completely different build qualities. If you are into hardware and build quality the Krells are the way to go.

Craig

 

[tarior]

You can but you need to be certified by Krell. It is just one of the ways that high end companies protect their equipment from hacks.

That is a fairly valid point. I've seen some ugly **** come out of so-called professional shops. Though I am more than certain that work like that tends to be done by personnel who don't bother with service manuals.
However, I still stick by my initial assessment of some of them either having something to hide, and/or wanting their customers on the treadmill.
My experiences with Meridian, Levinson, and Classe` in particular bear that out.

Even comparing Nakamichi with Threshold. Nak published full docs for all of their gear, including N. Pass designs. Threshold doesn't.
Nak is gone now, but we can still keep their gear in operation thanks to their excellent service docs.
Hi Fi companies go under all the time for various reasons. It would be nice if techs who actually care could keep these things alive. Tough to do without service information.

I had the privilege of repairing three Krells not too long ago, two KSA100MKII and a KMA100MKII. All I can say is WOW what amplifiers they are. Easy to work on, wwwwwwaaaaaayyyyyyy over built, and good sounding. They do run hot though, my repair was mainly replacing the roasted output transistors but the customer wanted the small electroytics replaced as well. Other than the power supply filter capacitors there are only two electrolytics in the signal path and they are in the feedback loop, the rest of the electrolytics are in the output relay circuit. If I had the choice I would pick the Krells, comparing the Krells to the Adcom is just not fair, completely different build qualities. If you are into hardware and build quality the Krells are the way to go.

Craig

Nice to know.

 

[damacman]

This series of Krell amps has always intrigued me. Apparently they’ve aged far better then the ML designs of that time that have cap failures.

The MC500 I just sold would also have been a nice match for your speakers.

 

[tarior]

It's funny. I remember drooling over ML, Mc, Krell, Classe', Meridian, etc. ads in Stereo Review and Stereophile when I was a kid.
After learning electronics and working on this stuff, the only ones that haven't been disappointing (excluding vintage) have been McIntosh and Adcom. Though there are few that I haven't dealt with at all, like Krell.

 

[Blue Shadow]

Same with the Adcom.

I think you were agreeing with DS2000, wanting the amp refurbished before purchase. Not really necessary if one can do that work themselves because the documents are available on line, not factory only.

I would still go with the Krell. It is just a better design.

Can't argue with that. Surprised a true high end manufacturers product is even being compared with a general run of the mill unit.

Same with the Adcom, and the Adcom doesn't have a protection circuit so when it goes, it will take the speakers with it.

Now you are just piling on that poor adcom. I believe that the lack of protection in an adcom is more frequently mentioned because it happens more with them than with other high powered amps that don't have that protection because the break a bit more frequently. Getting a fully serviced one is recommended for any used adcom buyer.
At least you did finally mention the sound quality difference and your reason to prefer the Krell.

I haven't been in a Krell amp but as @llwhtt said there is significant difference in build quality. I got a GFA-555 recently and was amazed at the chassis for that unit. Simply a piece of sheet stock bent to form a flat bottom U with a lip bent on the top of each vertical. That was it. The four amp modules are screwed to this chassis at the bottom into the heatsink. Top holds the parts in place on the other end. Once the top is removed the amp modules are floppy along with the input board and connectors. Strength of the unit as a whole is from small screws holding the amp modules, top and front panel in place. For a 200 wpc amp, I' more used to a solid chassis that will hold the components instead of rely on them for structural support. This Adcom build style allows it to sell for way less. It was also my lightest amp for power that I have owned. 200wpc/33 pounds vs. 200/45 for Cit 22, 185/50 for the DNA-1. Makes it one easy amp to move around considering the power. Those high end brands are in another league when it comes to weight for a 200 pounder but the Class A operation requires considerably more heat sink that an A/B amp.

 

[llwhtt]

These were the first Krells I'd worked on, the KSA and KMA amplifiers are simple, no computerized opto-bias or whatever the newer models have. Found the schematics on the interweb and went from there. All parts are still available except for a couple FETs but those could probably subbed with something else. Wouldn't hesitate for a second to work on a older Krell again. Now working on a ML is another story, been there done that and I would probably refuse to work on it, too complicated with no service lit. available. I might make an exception for the ML-2, everything is plug and play, looks fairly easy to work on.

Craig