best amp for BASS

My system is in a relatively large room 25x40 with 25ft.ceiling..It is a 5.1 system with meridian 861 and 800.German physics speakers.The Main speakers are Loreley large speakers each having four 12in.woofers.These are bi amped with Xover at 200Hz,with 6db slopes.At present the amps are YBA Passion 1000 mono blocks for the highes(fantastic) and bryston 14bsst for bass.The bass is OK but definitly not great.I would like to augment the bass amp.any ideas?
Get the biggest Krell's you can afford.

Yes indeed,nothing better than a Krell for bass!
FPB 300 or FPB 600 KRELL
Krell FPB300cx or FPB400cx (what I use)
I'm partial to Steve McCormack's DNA-2 Revision A amplifier.

There's something spectacular about the bass when using XLR connections thru-out with this particular amp. I've used XLR connections with other amps, including my very highly rated McCormack DNA-2 LAE(Limited Anniversary Edition), but I've not witnessed anything close to what the DNA-2 Rev A does with those 2 additional volts from the XLR connections.

Regardless of which amp you select, you most likely would be better served if you use XLR connections. With XLR connections, the dynamics and bass are most always at least a bit better reproducing just a bit more of that live bite.

Bass response is HIGHLY dependent the on the room and where the speakers are placed in the room . What you perceive as an amp issue might be resolved by repositioning the speakers or room treatments. Throwing money at the problem by buying better equipment will only take you so far. Since money does seem to be a major concern, you may wish to seek professional advice on room treatments and speaker placement.
If you like YBA, Krell may not be quite what you expect although it does have tight bass (the 600s on Wilson Sophias). FWIW, I had a Krell KSA 100 for a while and it was good but a little bright.

I liked the McIntosh MC1201 monoblocks the best however, slamming massive McIntosh XRT28 speakers like I have never heard before. Everything was shaking except for the amps and speakers (they weigh incredible amounts). I was impressed but it's a conservativly-rated 1200W per channel amp afterall. At any rate, try to audition whatever you can because room and system synergy are critical for any new component to sound good. Arthur
What great advice!Put the money back in your wallet and take a good look around.What you probably need to do is start to "see" the sound with a rat shack meter and a test disc.Or better yet a signal generator.You mentioned the bass was not up to par, is it weak ? Do the subs max out and make a mechanical distress sound ? How are the four twelves wired ? Do they have an 8ohm load (which would lead me to believe they are series -parallel.Not that Krell amps are not the answer some day, always look further to correct the problem.Sounds like a great system and a whomping big room.Amost willing to suggest old JBL scoops from the pro audio world for that big ol' room of yours.I just built some subs using Adire Tumults with some Adcom 555mkII's and they fit the bill.You may need a parameteric eq to remove room modes and really start to hear the bass.Good luck and post your solution.
Try the Crown K-2, maybe two K2's in bridged mode. Although it's cheap I expect that it will outperform a Krell 600 or 650.
I use a Crown K-2 for my Wilson Audio WHOW sub which complements my Watt/Puppy 5.1. It has fantastic control and power. As the WHOW is a mono sub I use the K2 in bridged mode. It has 1600 Watt @ 8 ohms (2500Watt@4Ohms). Damping factor is above 3000!
List price of a Crown K2 is about 1800$ only.
Use XLR connections with the K2 if possible!
Geez,I'd love to have a Krell for Mains let alone for using one just as a Bass Amp.

I always thought Bass was the easiest single driver to drive provided you have a high Watt capability along with good Damping Charctheristics.

Just thought Krell might be alittle of overkill for a Bass amp.

How about an older MUSE or as someone aluded to the McCormick's. Anyways,just thinking!
His speakers are 4 ohm rated, the specs. call out a minimum of 350 watts a channel and bass output is rated 110db at 18HZ.

Thanks for the inputs.I do use balanced connectors.The bass is very clean not boomey but not powerful.My guess is that having a large room with very few walls(the size was describing floor not the enclosing walls) will require lots of current with fast rise time,and large power supplies.I agree the best approach is auditioning different amps.However this is difficult if you do not want to pay retail and you are buying on audiogon.I did hear the Loreley speaker with Crown amps,definitly inferior to Bryston.I do not like the Krell amps for their highs and mids,but maybe for the bass they will be good what about the FBA600c?
Thanks for the responses.
As mentioned, the sound that you hear will be most influenced by speaker placement and room acoustics. Given the level of gear that you have, i would hope that you've spent some time working with those two subjects prior to investing anything further.

Having said that, look for an amp that has an "old school" iron core transformer ( no toroids ), has "gobs" of filter capacitance and uses what most would consider to be a huge output inductor. Since effective damping factor can be increased by manipulating negative feedback levels, it should be high but you don't have to go crazy with that spec. One can't obtain ultra high damping factors without playing games with figures and circuit designs. My experience is that amps that work fabulously for bass are not necessarily amps that you would want to run full range and vice-versa. Sean
On the used market I would recommend the Parasound HCA-3500 350 WATT/CH dual-mono amp!You can probably find one for around $1,000.00 to $1,100 used. Massive power supply, two huge toroid transformers, two power cords!The best bass I have heard!
Nothing conrols the BASS like Krell.

It is no contest, in my opinion.
Not a big fan of Krell, but the bass on those amplifiers rule no question. We ran a real muddy pair of Kef Reference Model 2's with a small Krell amp. That amp did wonders for the bottom end of a pair of speakers that used a crappy bandpass configuration with very poor bass drivers to begin with.

If money is no object, Ill vote Krell as #1.

A very close 2nd for 100% total bass control would be the Aragon Palladium's(not the 8008BB). For pennies on the dollar your getting 99% of the Krell's bass performance for less to alot less money.

Parasound alos makes SS amps with killer low end punch and detail. Ill put them in the top 5 category.

A few others I think are worth mentioning are Pass Labs and Linn.

Linn makes a killer pair of super efficient monoblocks that are just awesome sounding from top to bottom with no weaknesses.

Pass labs may be the most "refined" sounding of em all, could be a bit too refined for some people though. I have heard a pair of x600's powering a pair of Revel Sub 15's through a custom external xover.The monitors were powered by a pair of MAC 2102 tube monoblocks to a pair of Aerial 5B's. I was completely blown away is all Ill say no matter what disc I put in the CDP(BAT VK-D5). This guy had his room dialed in too. It was awesome.
Ramy: as per your request, here are some basic suggestions. Obviously, some Krell's make for great bass amps but there are also some others that are very worthy contenders. Before mentioning some models though, here's a thought for you. Quite honestly, it is what i'm doing with my main system.

Like you, i have four 12's per side, each of them rated at 4 ohms. In order to maintain dynamic headroom and keep from going too low on the impedance, i split the four drivers per side between two channels of an amp. That is, i run both channels of a stereo amp for one side. I have two 12's on Channel A ( 2 ohms ) and two 12's on Channel B ( 2 ohms ) of the same amp for the right channel. An amp with a small output inductor just would not work very well at this low of an impedance. I then have a duplicate amp wired up the same way to drive the left channel. This is more expensive, but works killer to say the least.

I've used the same approach for the mids and the tweeters too. In effect, i have six stereo amps acting as mono-blocks in an actively tri-amped system. All twelve channels are driving multiple drivers per frequency range. This allows them to share the low impedance load without any one channel or amp ever getting stressed. Things are "cleaned up" even further by actively crossing the amps with a sharp slope, therefore limiting the bandwidth that each amp has to cover. You could do much the same thing with your woofers should you choose to go that route.

As for the amps, i'm running two Perreaux PMF-3150B's with two ohm loads per channel. This results in about 800 wpc x 4 channels driving my subs. If i could find them at the right price, i'd like to snag two PMF-5150's. I "think" that the 5550's would also work well here too, but i'm not sure if these use iron core transformers or toroidals. I don't know when Perreaux switched to using toroidals, but i think it was after the 5550 series. Having mentioned Perreaux's, i wouldn't use 2150's, which are relatively abundant and cheap, for low frequency reproduction. Even though these were rated at 200 wpc @ 8 and clipped at about 280 per channel, they were earlier designs. Peter Perreaux revised the design of that circuit and the results are FAR superior in terms of bottom end "oomph" with later models.

Other amps worth considering for "booty busting bottom end" might be Classe' M800 or M1000 mono-blocks ( 800 wpc rms and 1000 wpc rms mono-blocks ). These are huge behemoths to say the least. Other BIG Classe' amps ( 300's and 400's ) might be okay for bottom end, but i don't really like them at higher frequencies. I would not doubt that these would be better choices than the Bryston that you currently have though. As many folks here know, i am not a fan of Bryston amps even though their customer support is the best in the business. I know that Pbb won't be mad at me though as i just recommended another Canadian company to take their place : )

As mentioned above, using a pair of smaller amps might also do the job. In this case, you might try a pair of Aragon 8008's or Electron Kinetic Eagle 7's. A factory MODIFIED ( not stock ) Sunfire ( or two ) or ( preferably ) a Sunfire Signature amp ( or two ) would also work well. Any / all of these amps could be further updated / optimized / modified for very specific "low frequency reproduction". Some of the earlier Threshold amps might work well, but they would require a lot of upgrades compared to the others mentioned. I've never considered any of Nelson's designs that i've heard to be "killer" in terms of "bass thump" although i love everything above that range on many of his amps. The newer X series might be an exception, as these amps have absolutely huge power supplies. I would not even think about using one of his Aleph's or the newer XA series for something like this though.

Hope this helps and gives you some ideas to think about. I know that using two stereo amps with all channels driven is not something that most folks would normally do, but it definitely has its' advantages in this type of situation. Sean
If you need to save money (as in I am on a budget), buy a Krell KSA-300s, this is the amp that many Apogee (very hard to drive) speaker owners use to drive their bass in Bi&Tri amped systems. This amp will drive your bass as well as any of the new Krell's. Get one thats been back to Krell in the last couple of years...they come up for sale here on Audiogon often at around $3,500 fresh from a trip to Krell service.

I must apologize to those of you who responded to my question and to Bryston.When the dealer installed my meridian(the meridians installation are beyond me and most older hobbiest) and the bryston he set the amplifier with the wrong gain,on ballanced inputs it had the low gain ie 100watts @8 ohms instead of 500 watts@8 ohms.What a difference it made the system sounds great.Bryston thpough is not totally blameless it doid not provide a manual for the 14Bsst,only after downloading from the web did I discover the set up error.I do appreciate all of your inputs,Someday I may try the Krell 600 or 700fba I have a hard time placing a n amplifier which is deeper than 24".
Thank you
I just sold my Classe 15 which had excellent bass. I have heard the Krell 750monos at a friends and they were awesome, simply staggering sound quality...then we realized that we were listening to the AudioResearch tube amp sitting between them. A big older 250watt tube job, go figure. The Krells were excellent too but for the price it was a no brainer.
My two cents.