Amp for Nautilus 805

[gchronis]

Hello folks,

I am looking for an amp for an old set of Nautilus 805.

I am building a system for a new small office: 9ft x 12ft with 8ft ceiling, wooden floor. Here are a couple of pictures to give you an idea of the layout: https://www.icloud.com/photostream/#A35CmvASDC96v

I now have the B&W Nautilus 805’s from another room to save some money from buying new speakers and got some Energy 5.1’s for there temporarily. So, now I have the 805’s, a Schiit Mjolnir headphone amp (which is all balanced and has Pre outs as well) and the Audeze LCD-X headphones. I have a Marantz NA7004, which I mainly use as a DAC, that I got at a really nice price. I use a MacBook Pro for source (24/192 usually). I’m currently powering the 805’s from an old Pioneer Elite VSX-36TX I had laying around. That’s 100W @ 8Ω. The 805’s have a recommendation for 50W-120W amp. This is a fine amp and the speakers sound great, but it’s really a receiver, not a dedicated audio amp and I’ll eventually use it for a patio setup in the summer. So, I’m looking to buy a stereo amp for this room, which will be used more around the year, rather than buy something for the patio.

Here are a couple of options I’m considering:

1. Emotiva monoblocks like the XPA-1 and use the Mjolnir as a preamp - all balanced. This will give me 60W of pure class A, if I switch it to that.

2. Marantz PM8005. This has an output of 70W.

Since I’ve never heard a class A amp on speakers, I wanted to ask your opinion on what difference that would make in my case. And is it worth going the monoblock route, separates or integrated? Whatever else you may want to suggest, I’m all ears (and eyes).

Thanks for any advice you can provide.

George.

 

[PENG]

Class, A, AB are very matured technology. If we restrict ourselves to amps designed to be accurate and that they are working within their limits, a good class AB can sound better than a not so good class A. Differences heard by many people (hearsays) could be due to other factors including placebo.

If B&W recommends 50-120W, and if you must try a separate amp, any class AB rated 100 to 200W by Rotel, Marantz, Anthem, Parasound, Bryston should be fine for those B&Ws. I highly recommend the Parasound Halo A23. The big and heavy XPA-1 seems like an overkill in that small room. For short cable runs, I would just use RCAs unless you have the balanced cables already otherwise why spend the money when there is nothing to gain.

 

[PENG]

Class, A, AB are very matured technology. If we restrict ourselves to amps designed to be accurate and that they are working within their limits, a good class AB can sound better than a not so good class A. Differences heard by many people (hearsays) could be due to other factors including placebo.

If B&W recommends 50-120W, and if you must try a separate amp, any class AB rated 100 to 200W by Rotel, Marantz, Anthem, Parasound, Bryston should be fine for those B&Ws. I highly recommend the Parasound Halo A23. The big and heavy XPA-1 seems like an overkill in that small room. For short cable runs, I would just use RCAs unless you have the balanced cables already as there is nothing to gain in terms of sound quality.

 

[AcuDefTechGuy]

I would get the ATI AT1202 120WPC Stereo Amp brand new for under $700.

http://www.ati-amp.com/AT1202.php

 

[gchronis]

Class, A, AB are very matured technology. If we restrict ourselves to amps designed to be accurate and that they are working within their limits, a good class AB can sound better than a not so good class A. Differences heard by many people (hearsays) could be due to other factors including placebo.

If B&W recommends 50-120W, and if you must try a separate amp, any class AB rated 100 to 200W by Rotel, Marantz, Anthem, Parasound, Bryston should be fine for those B&Ws. I highly recommend the Parasound Halo A23. The big and heavy XPA-1 seems like an overkill in that small room. For short cable runs, I would just use RCAs unless you have the balanced cables already otherwise why spend the money when there is nothing to gain.

Great feedback, indeed. Thank you, very helpful. I tried to learn more about A and AB, but it starts getting very technical and I was looking for more information on what the resulting sound is, not so much how it works. Your answer is exactly the information I was looking for.

I don't HAVE to try a different amp. I just have to buy another amp for the patio and I thought that I could buy an amp for this office instead, so I can use the Pioneer in the patio. This way I'd have a "better" amp in the office, where it will be used more. I am definitely happy with the Pioneer; just don't know if I'm missing anything. I will definitely look at the Halo A23.

Balanced is not a big deal; I just had the balanced preamp and the XPA-1 happened to have balanced ins. I do have the balanced cables (from another application), but I also have RCA's and of course speaker cable, if I'm not going to go with monoblocks. From what I have been reading, it's better to have the long runs on speaker wire than signal on RCA, anyway.

So, thank you again, very informative.

 

[gchronis]

Here are the specs of my Nautilus, btw, if that helps...

Description: Two-way, stand-mounted, reflex-loaded dynamic loudspeaker. Drive-units: one 1" (25mm) metal-dome cooled tweeter, one 6.5" (165mm) woven-Kevlar bass/midrange cone with 1.24" (32mm) voice-coil. Crossover frequency: 3kHz. Crossover slopes: third-order Butterworth alignment with 49Hz cutoff. Frequency response: 49Hz-22kHz, ±3dB. Sensitivity: 88dB/W/m (2.83V). Nominal impedance: 8 ohms (minimum: 4.6 ohms).

Amplifier requirements: 50W minimum, 120W maximum. Maximum recommended cable impedance: 0.2 ohms.
Dimensions: 16.3" (415mm) H by 9.4" (238mm) W by 13.5" (344mm) D. Weight: 20 lbs (9kg).

 

[PENG]

I will definitely look at the Halo A23.

When you do, note that the A23, rated 125WX2 has the following power supply specs:

850 VA transformer, 48,000 uf capacitance, versus

XPA-2, rated 300WX2:

1,200 VA transformer, 45,000 uf capitance, and

XPA-3, rated 200WX3:

850 VA transformer, 60,000 uf capitance.

You can see that the A23 has more generous power supply capacity for its rated output power, relative to XPA amps.

Balanced is not a big deal; I just had the balanced preamp and the XPA-1 happened to have balanced ins. I do have the balanced cables (from another application), but I also have RCA's and of course speaker cable, if I'm not going to go with monoblocks. From what I have been reading, it's better to have the long runs on speaker wire than signal on RCA, anyway.

The Halo A23 has balanced inputs.

Again, you Pioneer Elite should be capable of 100WX2 and probably 150WX2 into 4 ohms. That's enough to drive your 805 for serious Stereo music enjoyment. However, you will likely perceive better sound quality from the A23 as Placebo effect can be highly effective when you are already thinking Class A and balanced connections. The A23 will get you the taste of both, so you are well prepared to be biased, in a positive way.

 

[TheHills44060]

Both the ATI and Halo are great suggestions for the 805's. It's been almost 20 years since I had the chance to play with an ATI amp but the experience was a good one and the Halo's seem to be very versatile as I have not heard a bad speaker combo with them yet. I wouldn't bother with an Emotiva since you get what you pay for with them when it comes to their amps.

 

[gchronis]

Got it. Thanks Peng. I've been reading all about Parasound and the A23. I have to admit, I don't know as much about speaker amps as I do about headphone amps. I've only looked at the run of the mill Marantz, Yamaha, etc. A lot of interesting options out there. I'm leaning toward trying the A23. Again, I am very satisfied with the Pioneer, but I will have to get another amp anyway for the patio. I thought I may as well get it for the office and throw the old Pioneer on the patio with some cheap Yamaha outdoor speakers. The Pioneer is also pretty big for the shelf I have it on (you can see in the picture) and I can't throw it in a corner somewhere. The A23 is looking great, because I will use my Mjolnir as the preamp with balanced interconnects. Much cleaner look. Even if the sound is the same as my Pioneer now, I'll be very satisfied.

One other thing with the Pioneer that I noticed is that if I have some source playing (say on the CD input) and I switch to another input that has nothing playing on it, I still hear the CD input through the speakers, if I go to -10db or more. That's probably some crossfeed of the integrated preamp, which I'm sure it will go away with the A23/Mjolnir combo. I can't hear any relays when I switch sources either, so it's definitely some cross feed. It's not something important of course, since I only have one source connected (the Marantz NA7004), but it's just annoying to know I don't have the cleanest signal lines in there. I really don't need all the additional circuitry of the Pioneer. That's when listening to the "direct" mode, btw, without the sound processors in the way (supposedly).

 

[gchronis]

Both the ATI and Halo are great suggestions for the 805's. It's been almost 20 years since I had the chance to play with an ATI amp but the experience was a good one and the Halo's seem to be very versatile as I have not heard a bad speaker combo with them yet. I wouldn't bother with an Emotiva since you get what you pay for with them when it comes to their amps.

Ok, great. I'll look at the ATI next as well. A23 is definitely more visually appealing and I like the balanced ins, because my Mjolnir preamp is fully balanced (no SE outs).

 

[AcuDefTechGuy]

However, you will likely perceive better sound quality from the A23 as Placebo effect can be highly effective when you are already thinking Class A and balanced connections. The A23 will get you the taste of both, so you are well prepared to be biased, in a positive way.

Right on.

Well, maybe that depends on the voltage gain of the Pioneer vs. the Parasound. If the Parasound has a lower voltage gain, the speakers will have less volume at the same master volume and trim level as before. Then the Pioneer will appear to sound better.

 

[slipperybidness]

When you do, note that the A23, rated 125WX2 has the following power supply specs:

850 VA transformer, 48,000 uf capacitance, versus

XPA-2, rated 300WX2:

1,200 VA transformer, 45,000 uf capitance, and

XPA-3, rated 200WX3:

850 VA transformer, 60,000 uf capitance.

You can see that the A23 has more generous power supply capacity for its rated output power, relative to XPA amps.



The Halo A23 has balanced inputs.

Again, you Pioneer Elite should be capable of 100WX2 and probably 150WX2 into 4 ohms. That's enough to drive your 805 for serious Stereo music enjoyment. However, you will likely perceive better sound quality from the A23 as Placebo effect can be highly effective when you are already thinking Class A and balanced connections. The A23 will get you the taste of both, so you are well prepared to be biased, in a positive way.

Just realize, I believe the A23 isn't a fully balanced circuitry design, just balanced inputs (or maybe just XLR inputs). It is still a fine amp, but I think balanced inputs without a fully balanced circuit design can be a bit misleading.

 

[PENG]

Just realize, I believe the A23 isn't a fully balanced circuitry design, just balanced inputs (or maybe just XLR inputs). It is still a fine amp, but I think balanced inputs without a fully balanced circuit design can be a bit misleading.

That is hard to say if it is fully balanced or not. That their documentation do not seem consisten at all. For example, depending on which document you read from their website, the power supply transformer for the A23 could be 785 VA, 1,000 VA or 850 VA if you email them. The same goes for the filter capacitance. The way they describe the balanced design in the owner's manual seems to indicate that all the Halo amps are of the differential design from input to output, but again, I really can't say for sure if it is or not. I don't care either because I know there is no audible difference to me. If I did care I would have emailed them for a definitive answer.

 

[PENG]

Right on.

Well, maybe that depends on the voltage gain of the Pioneer vs. the Parasound. If the Parasound has a lower voltage gain, the speakers will have less volume at the same master volume and trim level as before. Then the Pioneer will appear to sound better.

Well, if and when he is ready to A/B them we will make sure he volume matches them to within 0.1 dB to make sure the Pio won't sound better...

 

[gchronis]

Found a "factory refreshed" silver A23 on Audio Advisor for $712 and pulled the trigger. Comparison with the Pio coming up next week

Thank you to everyone for their feedback!

 

[AcuDefTechGuy]

Well, if and when he is ready to A/B them we will make sure he volume matches them to within 0.1 dB to make sure the Pio won't sound better...

Heavens forbid such thoughts. The Pioneer must lose at all cost.

 

[gchronis]

Heavens forbid such thoughts. The Pioneer must lose at all cost.

It better, cause I just paid 7 benjies for the A23.

I was going to get another amp anyway for the patio though, so no regrets. It's a good price for the A23 even if it's not as good as people claim.