I thought I would post some experiences I've had with running several different types of amps with the 1801's. The amps I'll describe are:
Yahama R-V703: A standard off the shelf be$t buy receiver that probably cost all of $150 when it was new. It's rated at 70W/ chnl, but I'd bet that was just one channel driven, see dicussion below.
Sony DA4-ES: Sony's last high end analog amp released in 2003. It's rated at 100W / channel
NAD 2155: 1980's vintage 2 channel amp rated at 55W / chn. The power cord is not very big (18 ga?). The power cord on my 30W soldering iron is bigger. One transformer for the entire amp.
Adcom 535: Late 80's vintage 2 channel amp rated at 60W / chn. This would seem to have a beefier power supply than the NAD. It has one transformer per channel. This amp is recommended on ...
Parasound 2200 MkII: Mid 90's vintage 2 channel amp rated at 290W / chnl. Highly rated at the time by stereophile. I use it in mono (1000W) for my diy sub and this thing ROCKS.
Golden Tube SE40-SE: Mid 90's vintage tube amp that is highly thought of in certain communities. It is in stock form and the tubes were just biased.
Preamp for separates: Adcom 565. Mid 90's vintage pre-amp that was highly rated at the time by stereophile. I'm not so sure this preamp is very good, but it's the best I have at the moment. I'm working on this
Source: Marantz DV-8400. CD/ SACD/ DVD-A player.
Cables: Parts Express OFC 12Ga.
Musical Selection: Natalie Merchant - Live (CD). I'll report more musical selections within each amp review, but this is the only cd that is consistent among all amps.
The 1801's were run semi-flat with respect to the tweeter level. This is to say, the series resistor was 7 ohms and the parallel resistor was 12.5 ohms.
A moderate volume level is around 85 dB sustained. Loud is over 90 dB sustained.
On to the review and I want to apologize at the outset because I can't really write using the same flowery language that the stereophile guys write with:
Yamaha - In a word, "ugggghhhh". This wasn't very pretty and I couldn't listen to it for long. I don't think it had anywhere near enough power to drive the 1801's, as this thing was meant to drive those tiny speakers that come with it. There was absolutely no soundstage depth at all, everything was on one level, right out front. Width was almost as bad. I'm guessing there was alot of distortion because the vocals just didn't sound good. The bass was heavily artifacted, I'm guessing this was also distortion. The mix of the music was also incorrect, as it was very boomy in the bass and in the vocals. Just yuck, I turned it off. If one was looking to build the 1801's and all one had was a cheap japanese receiver, I'd say use your budget elsewhere. Build a Dennis Murphy MB20 or Plop-in-the-Box and buy a used, low power NAD reciever. You'll be much happier.
Sony - Now we are getting closer. This will drive the speakers and would work in a pinch. I'd rather have this reciever and the 1801's than almost anything else I've ever heard. This isn't to say that the Sony is great, it's not. It works and if I had never heard anything else, I'd be happy (maybe). The sound is sterile and dry. I think the 1801's make the amp sound just like it was designed to sound. There is nothing very magical about it, it's just there. Soundstage depth is ok, not great. Width is fairly narrow. Bass was ok, but I could tell that this amp also didn't deal well with the heavier, punchier bass. The bass wasn't articulated well, it came across as hollow. Maybe distorted? Midrange was ok and tolerable. Highs were not very detailed and there wasn't much "air" around cymbals, etc.
Adcom - Better. Bass is better than the Sony reciever, it is more coherant. Midrange was ok to ok+. High's were slightly raspy and it is a tad too bright. Again, nothing special, but it's definitely the best so far. Sound depth is better than the Sony and so is the width. I had the cover off of this amp and was able to monitor the voltages in the power supply during some loud vocal passages. With no load, the PS puts out about 51.6 DC. My Fluke tells me the minimum voltage during a loud passage was 47.8 DC for a voltage drop of close to 4 volts. I don't believe this is good, as it leads to distortion. During these loud passages, the vocals didn't sound very good either.
NAD - Better still. The midrange and treble sound the best of all amps so far. Soundstage depth and width is also the best. Bass isn't as tight as with the Adcom. I was able to use a speaker line relay switcher to switch between this amp and the Sony reciever from my listening position at will. The NAD's soundstage was wider and deeper. There was more detail (or is this grit?) around cymbals. It was more musical and is much more enjoyable to listen to than any amp so far, One drawback, the bass wasn't as tight. I think it's underdesigned power supply really hurts it here. If I want to listen to rock on the 1801's and turn it up, well this amp really doesn't cut, it runs out of steam.
Parasound - Things start to get interesting here. This amp definitely has the balls to deliver bass. The bass is tight and not distorted, even at higher volume levels. The 1801's are very impressive paired with this amp from a low frequency standpoint. Midrange and highs are a different story. The amp doesn't do high frequencies very well, there is a lack of air around cymbals and such. It definitely isn't as bright as the Adcom. Midrange is ok, probably on par with the Adcom. The Parasound seems to do a good job with classical, such as one of the new Living Stereo SACD's, Scheherazade. WOW, the dynamics really shine as the music changes from a soloist to the full orchestra. None of the other amps I've mentioned can play with the Parasound when it comes to reproducing the large dynamic range at loud volume levels of a full orchestra. Trouble is, when listening at lower volume levels, the NAD is a better sounding amp. More musical. This may have something to do with the menagerie of electrical components within the Parasound. There are dozens and dozens and dozens of resistors, caps and transistors and the signals goes through three different circuit boards before it's done. I'm thinking less is better from a pure sonic standpoint.
Golden Tube - Very interesting. Overall, not as good sounding as the NAD. However, this amp does have a pleasing midrange and female vocals though this amp and into the 1801's are heavenly. Mary Black - No Frontiers sounds the best I've ever heard it or her sound. Lots of musicality. The new Living Stereo SACD of Rubenstein Chopin's piano solo is gorgeous through this amp. It just sounds good. Very Good. Is it being faithfulling reproduced? I don't know. The problem with this amp is that the bass is not as tight as the NAD. It's not bad, it's just not tight. I'm guessing this may be because of a lack of power. In addition, I've been unable to reproduce a sharp, fast attack with a stringed instrument (guitar) at moderate volume levels. I'd really like to hear a pair of these amps, one for each speaker. Back to the flaws. The highs seemed to be rolled off, as there really seems to be a lack of air around all high frequency sounds. But again, oh that midrange. I love it. If this amp didn't roll off the upper end like it does, it would be marvelous. Finally, this amp by itself lacks power and won't play very loud. It'll play loud enough to give one a headache over a long period of time, but it won't blast you out of the room.
What have I learned from all this hard work (heh)? Well, the 1801's like power if you want to play them loud like you might with rock or a full orchestra. Decent electronics are a must. If a reciever is used, then it should be as good a quality as possible. Stick with Rotel or NAD. Lesser power seems to give a better sonic signature at the expense of woofer control when one turns up the volume. If you never listen to music very loud, then the lower power amps I'm using are fine.
I'm going to build an AKSA 55W amp, but after listening to all of these amps, I'm a little concerned that the AKSA 100W amp might be a tad bit better for me.
This has obviously been my opinion and in some cases it differs from what Dave (along with others) has heard and written about. My observations about power and bass may just be the fact that I'm using older, low power amps. I'd like to hear how the AKSA 55W stacks up against the Parasound in regards to woofer control during a full orchestral passage at a moderate to loud volume levels. I'll get to do that later this year when I build it
Jim
