What Power Amplifier Should I Buy?

After all this discussion of power, I bought a Bryston BP-17 cubed preamp. I'll get it next week. This discussion has convinced me that I have enough power from my power amp. So I decided to see if the much newer BP-17-3 can outperform the aged Levinson #38s. I hope so.

@kevemaher - I suspect the crossover is not the biggest issue. I actually own a Sublime K235 (their newer model) and it seems pretty good although I don't currently have in my system. The graphic equalizer has many more lower-quality op-amps and capacitors in the signal path, so I think this is probably the bigger issue. 

If you really need equalization, I'd suggest looking for a decent DSP preamp, such as the Anthem STR or DEQX Pre-4.

Another option is the Danville Signal DSP Nexus. This isn't quite as fancy from a case-work perspective, and the software is quite complex (but there is good support), but the sound quality is pretty good using the latest AKM DACs. I also have a DSP Nexus 2/8 that I've been playing around with. 

And then there are the Trinnov systems although I don't know if their products support a phono preamp or even analog input.

@jaytor Yeah, I have always had concerns about the EQ. But some form of EQ is needed to help tame some of the FR variations from the room.

I have traps which are very effective. I don't need more, except for the floor to ceiling mode. But the "rules" prevent me from doing that. I have worked very hard at positioning the speakers and the sub to get the best FR, but there are still +/- 6 dB variations in the bass. I am restricted to near the present locations. I have tried a miniDSP Flex. It doesn't affect the time domain at all and is barely better than the analog EQ. I ditched that. And I enjoy the idea that I have an all analog signal path (except for the CD/DVD and music files).

So the dBx EQ is a somewhat "necessary" evil. I could live without it, but the engineer in me strives to have as perfect FR and TR (Temporal Response) as I can manage to obtain.

The XO does a very good job, far better than the Rane I once used. I don't like the idea of running the f208s full range and band limiting the woofer. However I haven't tried this in a while. Might be worth a shot.

Are you aware of any reviews on the Sublime XO?

Very helpful advice. Thanks.

My guess is that the dbx equalizer and sublime crossover have more to do with the lack of dynamics than anything else. These are both low cost devices with inexpensive opamps. In the case of the equalizer, you have dozens of opamps and cheap slider pots that you are running the signal through. 

The CODA 07x preamp also has dual XLR outputs (I think it also had an RCA).

It is a warmer tubey sounding preamp than the LA4. I kept the LA4.

The BP17 is great with the 2.5, best match I had with those amps. There is a brand synergy there for sure. I haven’t heard the BP19 or BR20. The Benchmark LA4 is one of the best preamps I’ve ever had, especially as far as neutrality goes. It is a gem and at its price a tremendous deal. But for synergy with Bryston amps I’d probably get a Bryston preamp, if it were me. Plus as you mentioned you get the dual outputs.

Lastly, another option if you want to stick with Bryston and/or save some $$ and shelf space, the B135 integrated has preamp outs.  So you could use that with your 2.5B to horizontally biamp.  

@kevemaher thats why I recommend not using them as monoblocks, which is what Bryston is talking about. In this case they are bridged and each amp becomes one channel and doubles the power into 8 ohms. Try to find specs though on what they put into 4 ohms when bridged. It’s not recommended for speakers like Revels.
If you use one channel though from each amp to power the highs and lows of a speaker you let the amplifier ‘see’ a much easier load than if it was powering the whole speaker, and offering much more headroom. Active speakers (like ATC) have an amplifier for each driver in the speaker. You’re right, and as I mentioned in my first post you need a preamp with two sets of outputs or you can get a y-splitter for your preamp. Incidentally, when I had two 2.5s I tried them in this configuration as well as bridged monoblocks, powering the Revel 228 Be. It sounded ok as monos but not as good as the other way. A bit muddy. And two amps definitely sounded better than one, but the difference was not huge.

I don’t think you could go wrong with a 3B or a 4B, but I was looking at it from a price perspective. Probably cheaper to pick up a used 2.5. But also, from a power perspective, 2 smaller amps may be better than one larger. The 2.5 is conservatively spec’d. It’s basically a 150/300 w amp into 8/4 ohms. So biamping, at 4 ohms you’re getting 300 w/ch into the mid and tweeter, and 300 into the woofers, and each amp channel sees an easier impedance load. With something like a 4B you would get 500 w/ch into each speaker and it will see the combined load of the whole F208.

@scm I deliberately crossover at 100-120Hz because of a nasty room resonance at 40Hz. This creates a big dip at 80Hz that can't be EQed away very effectively. This dip is very strong with the f208 speakers. It is much smaller with the sub. I've placed the XO frequency a reasonable distance from that resonance. I've used REW and other tools to guide me.

I've listened to sub only at 75, 100, and 120 Hz. I cannot hear voices at all. Frequencies below 200 Hz are radiated into a half sphere, with no dependence on angle. How can this muddy the sound?

Of course, I could be wrong. Could you explain how this higher XO frequency creates muddiness? Thanks.

Two subs may be the way to go.

@jimmy2615   @perazzi28 

I've talked to Bryston about bi-amping. They recomment against doing it because the speakers drop below 4 ohms at the xover to the highs (2.2 KHz), although they hedged saying I moght be OK because there's not much power/current needed at that frequency.

I'm not taking that chance.

Biamping will give me more power only if I use two outputs from the preamp. Not very many preamps have two (balanced) outputs. The ML 38s doesn't. But the Bryston BP-17 cubed does!

What's the word on this preamp? I've looked at it before thinking I would try it or the Benchmark LA-4. I wound up getting a Cary tube power amp. That didn't change the sound very much, so I went back to the Bryston amp.

Two things come to mind.  The vintage pre-amp may not be up to the task. Ensure that you choose a preamplifier with 2 outputs.  Ultimately consider bi-amping, running the Bryston's on the low-end and something else on the tweeters.  Could be another stereo amp or monoblocs?  You have options with the Bryston's like "jimmy2615" stated.

I have three ideas for you but one was already mentioned. Adding a second complimentary subwoofer would help. It's adding more watts, more sound and also taking some load off your main amp (which you like). When I did this, it really opened up the overall soundstage and I felt more amp was producing more realistic organic sound. The second idea I offer is to do the first thing (add second subwoofer that is the same model) and add mono amps of the kind you have. Bryston makes good amps, and if they offer mono amps, I think that would keep that good sound you stated you like. Third idea is to change speakers. I know this maybe a less popular idea, but the facts are some speakers are MUCH easier to drive than others and still sound great. I have had my share of speakers and that is simply an easy solution. Good luck.

@kevemaher 

One likelihood (based on my experience with F208s) is that your current amplification already outclasses your Revels. In other words, the speakers are likely a bigger bottleneck in the grand scheme. The 208s are nice speakers at their price point, but you’d likely get more “bang for your buck” by saving money toward a pair of pre-owned Salon 2s or others of similar clout.

IME, even a mid-tier integrated amp can scale up surprisingly well with >/=$10K speakers. I realized regrettably late in this game that loudspeakers are the major bottleneck in probably 90% of audiophile systems, even when a relatively humble amplifier is employed. For example, I am quite certain I’d rather be stuck on the proverbial “desert island” with my Børresen X3s and Yamaha integrated than with Revel 208s and cost-no-object separates. 
 

…just something to consider 🫣
 

 

I never heard the A21, but I was very impressed with the A21+. For the cost it was an excellent amp. I sold that to get the CODA #8 and thought it was more detailed and as powerful as the A21+. I now have the CODA #16 which is better than the #8. The Benchmark LA4 with the Parsound is a great combo. The Holo Serene preamp is another similar option.

The A21+ was disappointing for me. It produced plenty of grunt but otherwise I found it inferior to a 20-year-old OG A21 I had at the time. The A21 was/is considerably quieter and cleaner sounding. I suspect that’s the real reason for why the 21+ is not THX certified despite its claimed specs. The original 21 was measured by Miller Audio Research lab back in 2011. Other than maximum unclipped power, it posted better numbers than the 21+ did in Stereophile’s measurements. 
 

I agree the Coda No.8 is more detailed—it has a lower noise floor than most amplifiers I’ve tried, which probably contributes to that detail. By comparison, the A21 is a little rolled off in the top octave, but on balance, I ultimately preferred the A21 for the way it “effortlessly” went about controlling the speakers, which I didn’t quite get from the No.8. I consider the two amplifiers roughly equal in subjective performance, but the No.8 sells for over 2X the money on the secondhand market, so in that sense I consider the 21 the better value, especially for tougher speaker loads. The difference in outright power between the 21 and No.8 becomes much more apparent on speakers like Magnepans. 
 

The potential downside of the A21 is that its inherently laidback character makes compulsory the use of transparent upstream components, like the Holo Serene you mentioned. That is, if the system’s speakers are voiced neutral or warm. 

StringAmp d220 power amp ( same designer as for the Gamut d200 versions)

Michael has perfected the design all these years and his amps are built to last a very long time. He told me that the amps are even better sounding now, a lot of great reviews on the old Gamut amps on the net for people to investigate.

Hope to get one myself one day.

 

Buckeye Purifi. Objectively one of the best amps on the market, and without the snake oil markup.

i have just the amp for you in your price range, recently retooled by jeff at conrad johnson, i dont play it anymore because i sold the preamp.  look under audiomart under conrad johnson, but its a mccormack dna 500...... 500w the 2nd best amp ever made.

Get a second HSU sub no matter what. Get one before making an amp change because two-four subs is where you want to be.

I`ve heard the Revel 208`s many times used with 3 HSU subs.

Running the subs up to 120 Hz is only going to muffle/muddy the bass up.

Use 60-70 Hz and play with Q settings and volume level.

Agree with YYZ I would not use the 2.5s in mono, but as I recommended in my post if you use them to vertically biamp your speakers (since they are biwirable) there are many advantages to that over a larger stereo amp.  

Orchard Audio Starkrimson Ultra DMC 2.5 is what you want. 

Once the A21 warms up for a couple hours it just sings. I prefer it to the $6K Coda No.8.

I never heard the A21, but I was very impressed with the A21+. For the cost it was an excellent amp. I sold that to get the CODA #8 and thought it was more detailed and as powerful as the A21+. I now have the CODA #16 which is better than the #8. The Benchmark LA4 with the Parsound is a great combo. The Holo Serene preamp is another similar option.

Using a stereo amp as monos is not a good idea. Better to get dedicated monos. I would get the stereo 4B3 over 2 2.5’s. A lot of technical explanations on Audiogon about why this is the case.

I am selling my Sanders Magtech amp (500 W) which I think is as good and maybe preferred over the 4B3. Definitely great on Maggies but I am not sure about the Revel and Sanders synergy. My Sanders was not as good as I expected on my Yamaha NS5000 but on my Magnepan LRS+ it was amazing.

The 4B3 should be good on Revel. I used to have the 4B-SST and then the 7B-SST on Revel Salon 1. It was not perfect but not too bad. The extra power of the 7B-SST was noticeable on the Salon 1. Such killer bass on that speaker.

My rec is to save some money by getting an old-stock Parasound A21. Parasound currently has some available direct from their factory store for a great price:

https://parasound.com/products/vintage-a21?variant=49660977873215

I’ve owned a good number of power amps <$5K and the A21 is as good as any of them and better than most. Its distortion profile is 2nd-order dominant and it’s considerably quieter than the newer A21+ (and sounds better too). Once the A21 warms up for a couple hours it just sings. I prefer it to the $6K Coda No.8.

I previously owned some F208s. The A21 amp paired with a low-distortion, low-noise preamp (Benchmark LA4, Bel Canto Pre5 for examples) makes for excellent synergy with the Revels.

@kevemaher . I would buy a 2nd 2.5B and use them as a Monoblock for each channel. 

pick up a PARASOUND JC5, fantastic match with REVEL.  gobs of power, images fantastically.  and slightly used can be had for $4500-5000

Still think, despite your devotion to them, the Revel's are your issue. Please don't shoot the messenger. Why not try something else? Vandersteen, Tannoy or Focal to name a few.

@soix Hi, I can understand your frustration.

Please tell me how I can clarify. I would like to keep seeing your inputs to my questions, even if it is not complementary. I value what you have to say.

I cannot explain why this XP-12 was a failure in my system. I did swap out other preamps such a couple of vintage APT/Holman ones. I had no problems with either. I even sent the XP-12 back to the factory. I live 30 mins from the Pass facility, so I hand carried the preamp to them and explained directly to the tech what I heard. He did find a problem with the older gain modules. He replaced them with modern ones and retested OK.  However, when I put the XP-12 back in the system. the sibliance was still there, unlike all three of the other amps. So I just don't know why I had this experience with the XP-12. I did everything I could think of to make it work.

The suspicion that the 38s preamp is masking a different problem may have some traction. The problem with the XP-12 occurred with all inputs, two phono cartridges Koetsu RS and Shelter 901, the Paragon as Phono preamp and the SUT, one Technics SL-1200G TT, a re-aligned Sansui TU-X1 tuner, and the Bryston BDP-3/BDA-3 combo. I can't see how each of these could separately create the same sibilance.

I have looked at the Bryston BP-17 cubed before. Perhaps I should pick one up and give it a try.

I am surprised at your experience with the Pass XP-12, I added one to my system this year and it is an excellent pre, with zero grain or sibilance that I can detect.

@zlone  @hkfan  Yeah, that’s why I’m throwing my hands up on this one.  Something’s just outta sync here along with an insufficient description on what the OP is looking for.  Sometimes ya just gotta punt, and hopefully someone else can help unlock this cryptic riddle. 

@zlone - I agree.  I have an XP-22 and it's outstanding.  I have zero sibilant.  I also had a ML pre prior to the XP-22 and bottom end is much more pronounced.

I am surprised at your experience with the Pass XP-12, I added one to my system this year and it is an excellent pre, with zero grain or sibilance that I can detect. I suspect that it is only exposing some issues with your source(s) that the ML is glossing over. I would try the Bryston preamp, and if you have issues there, then look further up the chain for issues. 

@kevemaher Last year I was considering the same amp you have. I talked directly to Bryston about my room and they said the 2.5 should have plenty of power. Your room is slightly smaller than mine. Based on that and your updated comments about improved transients I would consider scrutinizing the pre. I saw a well regarded poster on here one time respond to the question "What does a pre add" and the answer was "Richness". I couldn’t agree more after my testing.  Could that solve your SQ improvement needs?

Another thing to consider is the BDP-3 is now out of production. Although Bryston has a solid reputation of supporting OOP models there is no guarantee the BDP-3 will support the new OS3 that is in the works. The BR-20 Pre should have the hardware to support the new Bryston streaming OS. Then you pick up the synergy between the Bryston Pre and Amp. Fair number of reviews out there on the BR-20.

Well, I’m at a loss as to how you’ll get “more oomph” or “more power for transients” as I just don’t know what that means.  I will say that after looking at your setup I think it’s highly unlikely your sub is positioned anywhere near optimally in terms of working best in your room.  Not sure what method you used for how/where to place it, but it’s almost never where you have yours and something else to consider if it’s only there for convenience.  I’d suggest reading Todd Welti’s research or even just the subwoofer “crawl method” to get ideas on finding optimal/better sub placement in your room.  FWIW, and best of luck in finding what you’re looking for. 

@jbuhl Hi, see my system pics. Room dims are there.

Room Dimensions?

I liked the PS AUDIO BK250 as well. Like it so much I bought another and now vertically biamp.  It imparts of bit of tube sound, but has a solid state output stage.  I find it to be a nice compromise.  I have the F208s but they are not hooked up to the BHK 250.  Nice speakers though.  I should try it sometime with the BHK 250.  I was using a benchmark and I feel like the speakers had a lot more to offer then the electronics I had paired with them could extract.  

Wow! So many great ideas.

I appreciate how these posts have recommended changes to other components, so much so that I thought I would discuss my system in a bit more detail.

The Paragon System E is used as a Phono pre only. It creates a beautiful bloom in the upper bass/ lower mids. Sometimes this works, other times not too much. I have other phono preamps I switch in from time to time.

I tried a Pass XP-12 preamp earlier this year. It was not a good experience. There was a lot of sibilance, no matter what I tried, even with a tube power amp. I did not enjoy the ergonomics, especially the grainy volume adjustment. I sent it back to the factory where Pass replaced the gain modules, but the sibilance remains. I sold it. I've tried some vintage preamps, such as the APt/Holman Preamps 1 and 2 and a 10 year old NAD. The lack of a remote (not the NAD), takes a bit of the fun away, although the APT preamps sound very good. I refurbished both with new caps.

I use a graphic EQ (dBx). I'd rather not have to use it, but need more room mode control than the passive absorbers can provide. I've experimented with analog parametrics, but found them very difficult to adjust. I've tried the miniDSP Flex, but I was underwhelmed. I'm able to do just as well with the GEQ. And the Flex has no control in the time domain (impulse response, group delay, etc...). I need Dirac for that.

The Bryston music server and D/A sound great. I'm very pleased.

My crossover is a Sublime Acoustic K231. This is a modern XO. I've tried XO frequencies from 75 Hz to 200 Hz. At 120 Hz, I get some help from room modes that are more apparent than with the sub. I have run the f208s full range, but was/am concerned about clipping the amp. This is one place where I need to continue experimenting.

The Revel f208 speakers are a keeper. They are the best sounding speakers I've ever had. I need to find an amp that will drive them well instead of getting more efficient speakers.

My main reason for getting a more powerful amp is to provide more headroom (which is why I use a sub). Perhaps I don't need more power. This thought has occurred to me. I could spend the money on something else.

To summarise, I feel very good about the sound from my system. However, I am always on the lookout for something else (better or just different?).

I need to update my system pics and description. I've changed a lot of components since the last photos.

I am still open to changing the preamp. I have already tried Pass, so that's out.

This continues to be a very informative discussion for me. Thanks for your participation!

@kevemaher Wrote:

 Could you explain how a second sub improves the imaging and sound stage?

In my experience, a second subwoofer improved transient response in the bass and the sound stage became wider, bass notes became more delineated. Depth of image slightly improved. See here and here

Mike

What @larryi said that's great advice. Also putting a good tubed preamp in front of the Bryston you have could reap some benefits.

@mglik +1 also AGD and Gold Note should be on the list. 

If you want to greatly increase your musicality, transparency and detail I would highly recommend buying the Atma-Sphere Class D mono blocks.

They are in your price range. They are a fluid as a great tube amp but much more transparent and detailed with great bass and smooth highs. To get better you would have to spend many times more.

All of them then you can roll them.ive enjoyed emotiva dr 1.bryston 28b3.mcintosh class d 1502. Michi m8. D sonic.manly and carver tube. The fosi audio mono is a bang for the buck on Amazon happy hunting enjoy the music.

By the way, the advice on looking at preamps may be good also if yours is truly a ‘softer’ sounding unit. I preferred the Bryston amps with a Bryston preamp, it provided a certain jump factor that was very much missing with other preamps I tried, including Primaluna, SPL, and DAC direct. I used a BP17. The only thing I didn’t like about it was that it was noisy. Also, I eventually settled on a NAD M23 amplifier. 1st class D amp I would recommend over something like a Bryston, and I’ve owned the different technologies over the years, Pascal, Ice, Hypex, etc. The NAD gives up just a little bit of bass slam to the Bryston (not much though) but is otherwise more refined and has a nicer midrange, and provides lots of clean power (200/400w in 8/4 ohms).  It’s cheaper also, and IME was not a sideways move.  Definite improvement for my tastes.  

Instead of a bigger Bryston get another 2.5B and vertically biamp. I did this to good effect when I had Revel 228 Be. Don’t run them mono, but use each channel of one amp to power the highs and lows of one speaker, or horizontally one amp the highs and one the lows. That said, while the sound may be cleaner and you have a bit more headroom, the difference may not be that huge. You are probably only using a small amount of watts from your existing amp. I found it beneficial overall though, and I don’t listen that loud either.  Only issue is using a y-splitter for your preamp outputs if you don’t have one with two sets of outputs.

I cannot explain why two subwoofers over one increases the soundstage and can improve the imaging (through enlarging the soundstage)… it does. I have heard it, and others commented,  whenever disconnecting one of my two subwoofers when I used them.

I have two suggestions.

1. If you haven't already, try running your Revels full range and let the subwoofer just handle the lowest frequencies. You will need to set its crossover low - around 40 Hz to achieve this and don't run your Revels run through the sub crossover. You may find that allowing the woofers in the Revels to handle lower frequencies improves the punch factor.

2. The 203's are a fairly difficult load for an amplifier. The Bryston is no slouch but it does not increase its power into lower impedances as well as some other amps (Pass, Krell, Martin Logan, etc.). You might want to look for an amp that is rated to 2 ohms or where the testing shows that power increases substantially into low impedances. These amps are heavy and expensive to build which is why most amps don't perform this way.

Based on your current setup, it sounds like you're already in a great place with your Bryston 2.5B cubed, but I understand the desire for more power. The 4B cubed would be a solid upgrade, delivering more headroom and dynamic range without sacrificing the Bryston sound you enjoy. Given your listening habits, it will likely provide that extra "oomph" you're seeking without risk of clipping, especially considering your Revel F208's sensitivity and your subwoofer crossover.

If you want to explore alternatives, consider amps like the Pass Labs X250.8 or used McIntosh MC452, both of which are known for high power, clarity, and reliability. Either should fit within your $5K budget used. However, the 4B cubed's synergy with your current system makes it an easy recommendation.

Good luck!

Try crossing them lower, like much lower, say 60Hz. You're cutting the f208 above the knees by crossing them at 120Hz! I know these speakers well and realize they aren't bass monsters, but you can definitely let them play to 60 or even lower and flush out more punch.

This is a fantastic Pre. The Raven Preamplifier by Don Sachs and Lynn Olson. Lots more here on Agon. Yes I have one and it's rumored I'm a fan.

But Speakers are requirement one.

I agree that the pre may be the issue.  You might consider the new Bryston BR20 and collapse the BDP-3,BDA and pre all into one box.  The sale of those components cover a good portion of the BR

Another vote for a pair of subs.

Likely the Revel f208's may not 'get 'er done." ( You removed the Usher speakers. ) Perhaps investing in better $peakers is the key.

The single sub may be vibrating your gear especially the turntable. 

Room is well treated so it's not that.

Current is what drives a loudspeaker - not watts. If you want more "umph" look for a high current amp that puts out at least 40A. Basic math tells us at your listening distance your Revel f208 (with 89db sensitivity) will put out over 94db with 10 watts at 1 meter. So, its not watts you are lacking. As previously mentioned, Klauss at Odyssey Audio sells extremely high value, high current amps and I bet one of his amps would provide what you are looking for.