Best Tube Amp/Preamp combination with Quad 2805s

Recently upgraded my Thiel 1.6 paired with Krell KAV-400xi integrated amp for a pair of Quad 2805s. Told that the Krell pairing probably won't bring out the best in the Quads. Looking at PrimaLuna Dialogue 3 preamp and Dialogue 7 mono amps. Also advised to look at an Audio Research combination of pre-owned LS17 preamp with pre-owned VS115 amp.
The price combination for the PrimaLuna and pre-owned Audio Research actually comes out pretty comparable. I love jazz, jazz vocals, and classical music. I really want to find a combination in the $6k-$10k range that gives me the closest approach to that "live" performance. I love a big, natural soundstage, front to back and side to side. I just don't want something too analytical with the Quads that becomes fatiguing to listen to.
Any thoughts out there between the PrimaLuna versus Audio Research sound? Any other classic pairings to look at for my price range?
Think about an EL-34 based amp. I'm using a Luxman with a set of 989 and it's quite good. I've read that the CS 300(xs) is also very good with quads. I believe that amp uses 7981 or EL-84 tubes. Lower cost systems are certainly available from many companies like Dared, Jodila, Rogue, etc.... The thing about the Quads is they really don't require a lot of power. So you'll be good with 15- 30 watts. Based on the type of music you're focusing on you might want to start here.

Best of luck-enjoy!
Depending on your budget, I have used the following tube amps with great success with my Quads:
1. Atma-sphere M60 & S30 OTL amps. There
are a lot of Quad owners who swear by
OTL power amps
2. I also have used Audio Research amps with
current 2805's and ESL 63's. There is a
great synergy with AR and Quads. The Quad
rebuilder in Kansas City uses an all AR
system with all his Quads
3. My brother also has a set of Quads and
uses Lamm amps but they are way out of my
price range
Music Reference RM-10 with a Quicksilver or Conrad Johnson tube pre. It's a beautiful sounding 35 watt el-84 amp, the best I've heard so I bought one. I listen to the same type of music and I was using YBA solid state and wanted to try tubes. I use Vandersteens but I'm sure it would sound great with the Quads and you would have plenty left over in your budget.
Between the Primaluna and ARC I would take the Primaluna even though I am not a fan a Chinese tube amps.

The RM-100 is a better suggestion.

Also, since the 1950s, ESLs and OTLs have been the 'match made in heaven'. This is because ESLs are a Power Paradigm device, see:

Now if you read the article you now know that if you mix the two technologies, Voltage vs Power, you get a tonal aberration. The ARC is more Voltage than Power (uses a lot of feedback); you will find it does not play bass on the Quads very well.
Really interesting. Thanks for the reference. Also given advice to look at ModWright KWA-100SE/LS-100 combination, as well as VAC Integrated Sigma 160. Do these go along with the Power paradigm concept?
The Modwright is on the Voltage Paradigm. So on the Quads it will not make the bass that the speaker is capable of. You will have far better luck with the VAC.
After some extensive research, my thoughts are two of the best options out there for the Quads are: 1) Atma-sphere M40 MkIII.2 mono amps/M3a
pre-amp (with Zero-autoformers); and 2) VAC Sigma 160i integrated amp.
Any thoughts out there between these two options if you had to pick for your system? Strengths, weaknesses?
I assume you mean M60s, not M40.

Loved my Atma when I had appropriate speakers. But no experience with the VAC.
Well, *I* prefer our amps, so you will have to take my preference with a grain of salt.
I have the VAC sigma with a pair of Quad 57's. It is probably more power then I need but it sounds fantastic. It is a great amp and very musical. With the 2805's it would sound great.
I know that Quads have a reputation for getting along well with lower powered amps but if your 2805s are anything like my 989s, you might want to consider a little more power than 35 or 40 watts. This is just my 2¢ naturally but I've used both a c-j Premier 11A and a Premier 140, and as good as the 70 wpc 11A sounds with the 989s, the 140wpc of the Premier 140 takes the sound to an entirely new level in terms of clarity and dynamics. The sound stage, which was excellent with the 11A, solidifies, is better layered and expands with the higher powered amp.

As I said, just my 2¢.

Good luck with whatever you decide upon, the 2805s are supposed to be one sweet set of speakers.
hi Ralph,
base on your Paradigm theory, is ALL solid state amp belong to Voltage Paradigm? what about those amp which cannot double its power when impedence half?
Philipwu, now you see why the conflicts of these two paradigms has spawned the tube/transistors debate; yes, nearly all transistors are on the Voltage Paradigm, but not all- the Pass First Watt amps would be an example.

The Quad has a pretty variable impedance curve- which causes a lot of transistor amps to be bright in the highs and not play a lot of bass. If you investigate, you will find that most people that get bass out of Quads and transistors usually have the speakers only a couple of feet from the wall. This gets them some bass reinforcement, but only at one frequency.
I would like to reinforce what Joe_appierto wrote. Legends can sometimes be a big pain. People who are not familiar with the newer models keep repeating the wrong mantra. The newer Quads (2805 & 2905) can handle more power than their ancestors. In fact, they prefer more power.

Cosider amplifiers capable of 150W or more.

hi Ralph,
may i refer you to an Amp called AMPZILLA 2000 ver.2 Its spec mentioned :100% stable into any load angle 0 to 90 degrees, capacitive or inductive, regardless of waveshape.
is this Power or voltage paradigms? Thanks again.
I've noticed electrical phase & impedence varies greatly especially in electrostatics, will this amp serve better if it is Power paradigm?
Hi Phillip, If the amp can double power as the load is cut in half, then it is Voltage Paradigm. That is because the voltage stays constant regardless of the load.

The Ampzilla is an example of that.

The big variation of impedance in ESLs means that for most transistors, they can't make the same power into the bass regions that they can into the high frequency regions. Add to that that the speaker is really expecting the power of the amp to be the same at all frequencies. This causes transistor amps to not make enough bass and to make too much treble as I mentioned earlier.

That is why you generally want tube amps with Quads!
Ralph, this comment is obviously coming over a year since the last post. Nevertheless, if you catch my comment, perhaps you could respond to my question.

You mentioned that the Quad ESLs have impedance curves that vary a lot as a function of frequency. So, rhetorically speaking, why is that diffrent than most speakers?

My question goes to a point that you and Al (Almarg) have made on numerous occassions. Specifically, in order to know what type of amp matches best with a speaker, be it conventional, electrostat, etc., one should try to determine what the designer had in mind when he/she voiced the speaker in question.

So ... in the case of Quad ESLs ... do we know whether the designer intended that the model in question be driven by a Power Paradigm amp or a Voltage Power amp? My sense is that your posts above permit the inference the answer is Power Paradign amps -- not Voltage Paradigm amps. Is that correct??

Perhaps a match involving an ARC type tube amp, which as you observed uses negative feedback to lower output impedance, might be a better match if the Quad ESL is hooked up to the 16 ohm tap (higher output impedance and higher gain too). However, you might point out in response that using the 16 ohm tap might achieve a smoother sonic presentation, but using the 16 ohm tap might be a non-optimal impedance match. That is the back impedance presented to the output tubes off the primary windings of output transformer might be outside the optimal range of the output stage, possibly causing increased distortion?

Your thoughts??


Bruce, The answer is that the impedance of most loudspeakers relates to how the speaker behaves inside a box, along with its crossover components.

An ESL OTOH has its impedance curve based on a capacitor (IOW, a high impedance at bass frequencies, low impedances at high frequencies). The early Quads had a fairly high impedance at bass frequencies- over 45 ohms. In an attempt to get a little more power out of transistor amps, the later Quads like this one have a lower impedance in the bass, but the shape of the impedance curve vs. frequency remains the same.

As a result many tube amplifiers work better with the newer Quads when a set of ZEROs are employed, due to the lower impedance at high frequencies.

With your ARC, its likely that you would use the 4 ohm tap, but you would have to try it and see- its not always that predictable and you may be better off with the 8 ohm tap.

ESLs, because they are based on a capacitor rather than box resonance, have the same efficiency regardless of frequency so they are by definition a Power Paradigm device. If you drive them with a Voltage Paradigm amplifier, they can wind up being bass-shy and bright because of the amplifier's response to the impedance cuve (which, in most ESLs, varies by a good 10:1 change from lows to highs).

In a box speaker, the peaks in the bass are caused by resonance, meaning that the speaker is more efficient at those resonant points. The amplifier has to throttle back its power into those peaks to prevent tonal colorations (one note bass- bass boominess). As you can see, the principle of operation is different and is why matching the amp and speaker is so important.
Thanks Ralph. Your explanation is pretty clear. Just curious -- while ESLs behave like a giant capaciter, do they also have capacitive negative phase angles?

Also, as I asked above, does the amp/ESL match again come back to what the designer had in mind when he/she voiced the ESL in question? Working with your example, if the Quad ESL has an impedance curve that looks like it was a giant cap (i.e., high impedance in the bass and tappering off to low impedance as frequency increased), and if the ESL was voiced to be driven by a SS amp, plugging a Power Paradigm tube amp would make it sound like a tuba. Conversely, as you posited, if the ESL was voiced to be driven by a Power Paradigm tube amp, driving it with a SS amp or low output impedance tube amp like my ARC amp would make it sound like Mickey Mouse.

So my point is ... don't we gotta know what Quad or any ESL company had in mind. Otherwise, you're gonna have a great ESL product that sounds like a tuba or Mickey Mouse on estrogen if the wrong amp is used.

Do you know in fact what Quad has in mind with its current ESL offerings? I surmise that since you think one of your OTL amps would be a match made in heaven, an inference is permitted that my tube amp would not sound very good - (like Mickey Mouse on estrogen).
Bruce, Its not quite as extreme as that :)

You do get some capacitive phase angle. But most ESLs have a matching transformer too, so you have some inductive issues as well. Overall though other than impedance, all ESLs tend to be fairly benign in that regard.

I don't know of an ESL that is 'voiced'. When I look at the older Quads and the Sound Labs, they certainly aren't. In my book, 'voicing' is some sort of frequency compensation that has been introduced to make the device work a certain way.

I do know of an ESL that has tweeter and woofer sections, and is actually equipped with two woofers (where a Quad has only one). This particular speaker (which is not well known and is not an ESL that comes up when people talk about ESLs) only works with amplifiers that have a very low output impedance.

Martin-Logan loudspeakers have a low impedance and for that reason can be a difficult load for tube amps, but even they are not 'voiced' so far as I can tell- if you get a set of ZEROs you can drive them with a zero-feedback tube amp no problem (as long as the amp has the power). So I think the 'voicing' thing isn't, with regards to ESLs.

In recent years (since the ESL63 and ESL57) Quad has been going down the path of lower impedance, much like Martin Logan, in an effort to get transistors to be happier with their speakers. They have so far been more moderate about it than Martin Logan (whose speakers are typically rated at 4 ohms although they are only about 0.5 ohms at 20KHz), I think the newer Quads have been about 8 ohms (meaning their 20KHz impedance is about 1 ohm), as opposed to the old days when they were rated more like 16 ohms. FWIW the Sound Labs seem to come in around 30 ohms by the same measure.
I ran a pair of Quad 2905s with Conrad Johnson CT 5 and LP 70S for over 7 years. Amazing combination and available used in the OP's budget. Basically any CJ, ARC or similar tube amp with around 50 wpc should mate well with the Quads. Congrats on your selection of the Quads. Brilliant speakers.