ARC VSi75SE v. MF Nu-Vista 800

It seems there is a lot of items discussed here

1,The sound is right or not

2, The installation and operation is easy or not.

3, The basic model is valuable or not.

I am a guy to pay Audio research with more than 20 years.

1, The sound is right with Audio Research? YES 

Audio Research might have a lot of marketing problem,but the sound is very good.

By the way,I also understand the amplifeir MF. I have no good impression on their sound althought it is fully subjective.

2,The installation is easy or not. 

With Audio Research, I will say NO. I have VT100 MKIII,I change the bias myself with VOLT meter. The products is not so nice to clients.

But there is a point here. Auto bias is not the best way in my opinion.  

With auto bias,the machine bring the IC and the IC running all the time,and interfere the circuit. DO YOU THINK IT IS BEST FOR THE SOUND???\

BIG QUESTION HERE!

3, Does basic model value the money? Just like I/50.  

If you are talking about the sound,you best buy a old model from used market.

If you talk about the re-sell price, Audio Resaerch still good or better than most of brand.

I have my bad example here, I bought a 300B amp with no name,although the inside circuit is hand made, If I like to sell,it is very hard and I am doubt if I can get back 30% value.

Re: bias procedure for the ARC VSi75, yes that is correct.  There is a bias button on both  the remote and faceplate that will step through each of the four kt150 power tubes and show the individual mA values. There is a bias pot in front of each of the tubes that can be adjusted with the plastic tool.  It’s easily accessible with no need to disassemble the chassis, flip it on its side etc…super easy from a maintenance perspective. 

arafiq: Great feedback, exactly what I was looking for. Thank you.

Re: the C7 v. the 30.1, those two models are very similar, identical drivers & ports (admittedly arranged differently), similar cabinets, impedance curves, etc. The 30.1 is nominally 1 dB less efficient, so when I hear that a particular amp can drive the 30.1 well, I assume that I can extrapolate that recommendation to the C7.

FWIW, Alan Shaw claims that the C7 is his personal favorite model when driven with at least 80wpc. However, the XA25 is a high-current device (10A in the specs), and I suspect that its 30-ish wpc (into 6 ohms) is more powerful than you’d expect. And then there’s Herb Reichart’s high praise for the Harbeth+XA25 combination in his Stereophile 30.2 review. But still...

Your comments comparing the Lux & Pass are interesting. But I’d be even more interested in context. What size room, the type of content you played, volume levels, mounting, powered sub crossover freq, that sort of thing. I’m sure you’d agree that in this type of comparison, those details can make all the difference. In fact, your personal C7 experience seems to confirm Shaw’s (and Reichert’s) comments about these easy-to-drive yet finicky thin-walled boxes. Reichert found that even eliminating the blu-tak attaching his 30.2’s to Sound Anchor stands degraded their sound. And Shaw claims that, despite being designed to be insensitive to differences in cabling & ampflification technology, simply removing the grill cloths compromises his design. So again, devil in the details.

At this point, after digging through offerings from Levinson, PrimaLuna, ARC, Hegel, HiFi Rose, and Ayre, it looks like the XA25 & the Nu-Vista integrateds offer the best compromise among sonics, cost, connectivity/functionality, and form factor -- at least for my particular application. Even the INT-60, great as it must be, would not fit my system & room.

Unfortunately, there’s no way for me to hear these components before buying. All I can do is have long conversations with people who have had first-hand experience. And so far, there’s been no consensus about whether the XA25 is a good match with small-to-medium sized Harbeths like the C7 & 30.2. Many people, including trusted reviewers in Stereophile & TAS, describe in detail how beautifully they work together. But others, like you and Pass Labs’s & Harbeth’s own customer service reps, recommend more power.  Sigh.

One final question: Thinking of presentation, the things that the XA25 is noted for: holographic, three-dimensional soundstage, reproduction of room ambiance ("the players are in your room" v. "you are with the players in their own room"), realistic image size, Quad-ESL-like coherence, etc. -- did you lose any of that with the Luxman?

@cundare2 Please keep in mind that my experience was/is with Harbeth M30.1 and SHL5+. It is quite possible that C7-ES3s are a different animal altogether. I have owned P3esr and 30.1, and still own SHL5+ (home office) and 40.2 (main system). Incidentally, the C7s are the only ones I didn’t like when I auditioned them. But later, I heard a pair at a friend’s house and was quite impressed. I can only assume they were not driven properly when I auditioned them in person.

The reason I proposed a stout SS amp to drive them is because I believe the Harbeths already give you a tube-like presentation on their own. Adding tubes (with the exception of SHL5+) or warm sounding SS can be too much of a good thing. Secondly, they really shine with a ton of power and current. I agree that the sound can be more than adequate with many amps including INT or XA25. I was quite happy driving the 30.1 with tube amps and even PL INT-25 and told myself that it couldn’t really get any better. But once I put the Luxman in the system, the synergy was off the charts. The Luxman’s lively presentation was a good balancing act given the slightly darker sounding character of 30.1s. It was also better than the Pass Labs INT-25. If you are sold on Pass Labs, then perhaps INT-60 might be a better option to really give them the current they are craving for. So yes, the lower-powered amps can be ’more than adequate’ but IME more power allows them to reach their full potential.

Also, I'm not a fan of the Luxman sound in general. But it was a very good pairing with Harbeth M30.1. Not so much when I got the HL5+, which IMO and unlike other Harbeth models, is better driven by tube amplification.

In SS, I much prefer Accuphase and Vitus. You really get the best of both worlds, i.e. tube and integrated with these two brands.

@ghdprentice To be clear, my comments were specific to the i/50. It’s in a very competitive price bracket and I don’t think it’s a particularly good value given some other tube integrateds in the same ballpark. Apart from that, I am a huge fan of the Audio Research sound. I have owned VSi75 and GSi75 in the past and enjoyed them. But, IMO, the real magic starts at and above units retailing for > $15K.

I also love their preamps and consider them to be some of the best you can buy regardless of price. In fact, I might be getting the Ref 6SE in the near future.

Having said that, Audio Research doesn’t have a monopoly on ’natural musical perspective’, and neither are the AR owners the only ones who understand natural music :) There are many ways to get there.

classicalreflections:  So you're saying that the biasing procedure is much simpler on the VSi  than on the i/50?  You don't have to open up the chassis, clamp probes onto a resistor, etc.?

Hi cundare2- I have a couple of vsi75s paired with Proac 1sc bookshelves and d48 floor standers.  I recently auditioned the i50 prior to picking up the second vsi75.  Tonality was similar but I thought the vsi75 was more resolving and capable.  Sound quality aside, the other issue with the i50 was that it appeared to be manual bias only, whereas the vsi75 has individual bias for each kt150 that can be adjusted quite easily with the included plastic screwdriver.  Hope that helps and good luck with the search. 

arafiq: I’ve spoken to others who found the 25wpc Pass gear more than adequate for mid-sized Harbeths, but again, the devil is in the details. Can you give us an idea of the size of your room, listening levels, etc. when you found the INT-25 to be underpowered?

E.g., Was your experience closer to playing string quartets at moderate volume in an 8x10 room or blasting Black Sabbath at realistic volume levels in a 30x25x8 room?

Just trying to put things into perspective, since I’m about to purchase a simiilar amp for my Harbeth C7s without the ability to audition the gear before buying.

@arafiq

Actually what you say is completely consistent with the performance of these amps… for with someone who values lively detailed sound. Luxman would be perfect for you. Your comments on the Pass INT 25 sound right on, it is not that high a power so the Pass INT 60 would provide more solid sound. The ARC would sound a bit dead to you because it does not have the sparkle of the Luxman. Audio Research folks are looking for the natural musical perspective, and it delivers that (at an incredibly low cost).

@cundare2 Back when I still owned the Harbeth 30.1, I borrowed two amps from my friends to test. One was the Moonriver 404 integrated amp -- one of the worst amps I have ever tried. The other one was Pass Labs INT-25. It was very impressive but lagged behind in terms of dynamics. Finally tried it with Luxman 590AXII ... that was the ticket!

Now I know this might cause some heartburn for a few Audio Research fans, but I found the ARC I/50 to be underwhelming. Don't get me wrong, it's a nice piece of kit but you're paying a lot for the AR brand name. Right after I auditioned the ARC, I bought an Audio Hungary Qualiton a50i which, IMO, was a much better sound and value than the I/50. 

I later sold the 30.1 and bought SHL5+. The pairing with this speaker and Qualiton a50i was sublime. Oh, and the a50i is auto-biased, no need to take it to a technician for something as simple as re-biasing the amp. I mean who does that in this day and age?

erik: My understanding (and anyone with more currrent knowledge, please correct me) is that MF came up with a new variation on the old RCA nuvistors.  Supposedly, it discontinued the Nu-Vista 600 & 800 because of parts-availability issues -- but they were talking about front panels!

My SWAG is that MF is still working off its existing inventory, but has the means to manufacture more nuvistors as needed.  They actually sell nuvistor kits online.  And don't forget that tne Nu-Vista models are characterized as "limited edition."  I don't think they produce too many of these exotic beasts.

I thought Nu-Vista parts haven't been made in decades.  Is there a new manufacturing run?

OP,

On the topic of the Pass Integrated. I auditioned the INT 75 (and Luxman integrated $10K). What I was struck with was the excellent rhythm and pace of the Pass. It really got the beat with a pretty good midrange. I compared against the ARC I-50 and the Luxman… they formed a continuum from the bright detailed lean non-musical Luxman, the musical… well done solid state Pass and then the ARC - luscious but detailed musical sound. Big jumps between the three. 

OP,

I have got a seventy + year old back as well. I use talk and if necessary a $20 bill or two to deal with heavy equipment. There are all sorts of ways to arrange for you not to have to lift audio equipment. I will definitely not compromise the sound at my age to a trivial problem like my ego says I have to do this myself.

arafoq: The H590 is definitely on my short list, but some of the comments here suggest that even the entry-level ARC I/50 -- as well as MF’s limited-edition Nu-Vista products -- are in a whole different class. Again, w/o the ability to actually demo any of these amps, all I can do is ask and listen to responses.

The little Pass Labs amps, I believe, are quite robust when it comes to current sourcing. Wattage doubles, in fact, from 25 to 50wpc when going from 4- to 8-ohm (presumably resistive) loads.

One reason I’m considering the Pass now, at this late date (aside from reading so much praise from Audiogon users), is Herb Reichart’s rave Stereophile review, in which he pairs Pass’s integrated INT-25 with larger Harbeths than mine.

https://www.stereophile.com/content/pass-labs-int-25-integrated-amplifier

Btw, that review includes comments from Joe Pass himself about why his low-powered Class A amps "drive so many loudspeakers with so much dynamic authority and unmatched transparency".  Worth a quick read.

I love Harbeths. They need lots of current to wake them up. 
they sound really good with tubes but a solid state amp will drive them to their full potential. If you can swing it, look into Hegel H390 or H590. 
Good luck. 

Key typo in my last message: That list of "constraints" are NOT dealbreakers.  They're nice-to-haves, significant, but I'd work around them if I had to.

The advice I've gotten here is, as usual, excellent.  But TBH, I really am losing my mind.  “Overthinking”?  Well, yeah, maybe.

Priority #1 is giving my Harbeths whatever they need to shine, spending up to $10-12,000.  There are constraints, but are dealbreakers if the sonics are there.  The perfect choice would be an amp that:

i) my 70-year-old back can lift

ii) has an HT bypass

iii) will also work halfway decently powering the front speakers of a home theater (e.g., minimal warm-up time)

iv) has either a line- or speaker-level output for a sub

v) can be programmed to work automatically with a Logitech Harmony

I’ve considered several ARC & MF Nu-Vista models, as well as integrateds by Hegel, Levinson, HiFi Rose, and Ayre.  Bottom line is that the best-fit ARC model is its entry-level I/50, which lacks most of the functionality I want, but at least is light & has a HT bypass.  The Nu-Vista 800.2, which has just begun to ship, has an equally impressive reputation, but at 300/500 wpc and 90 pounds, it’s not perfect.  A better fit would be the lower-powered, lighter 600.2, reportedly due Q1 2024, but so far that’s just a rumor.

So maybe I need to rethink this from Square One.  I just started looking at a Pass Labs solution: the 20lb XP-12 preamp and 48lb XA25.  Just not sure if a 25wpc class A has enough oomph for the Harbeths, but I think Stereophile gave the Pass a rave review based on listening through a larger Harbeth model than mine.

Still, the I/50 is tempting.  It’s just hard to say whether I’d prefer the ARC or Pass “house sound”.  It’s not even personal preference, since there’s no way for me to audition either one first-hand.

I guess this is all part of the fun of this hobby!  Was it J. Gordon who defined “audiophile” as a person thinks more about stereo equipment than he does listening to it?

I contacted ARC directly and, as usual, it shot back an immediate response: The company does not recommend users biasing their own tubes but does so for general safety reasons.  The rep emailed me a 16-page illustration of the procedure.   It looks way more complicated than it needs to be -- even the Dynaco ST-70 was mroe user-friendly in this regard -- but it's nothng I can't handle.

This is from the manual.  But one has to wonder if they are afraid a person new to audio and tubes will shock themselves or if the unit is just unfriendly for anyone, even with experience, to bias.

MAINTENANCE

Vacuum Tubes It is recommended that you replace the vacuum tubes of your I/50 in sets. All of the tubes in your amplifier have been matched to have similar operating characteristics, to provide the best sound quality and reliability. 6550WE tubes should be replaced at approximately 2000 hours. 6922 tubes should be replaced before 4000 hours. Upon replacing a power tube or tube set, the I/50 must be biased by a trained technician to ensure proper operating values.

@cundare2 

Wow, that does not sound right.. but I can’t refute it with any knowledge. I’ll do a little research. I’d like to know. But it sure does not sound right.

Get the MF NuVista!  Why?  Because it's fits into your setup best.  Will it sound just like the ARC?  No, but so what.  It will sound great anyway.  If these are really you're only choices, then don't overthink this.

Now to overthink it, I would worry about having that much power being fed to the Harbeths, especially with other family members using them in the HT setup.

ghdprentice, I have a related question.

I see that the recent Stereophile review of the entry-level I/50 integrated notes that "When power tubes or the tube set are replaced, the I/50 must be biased by a trained technician to ensure proper operating values."  Holy cow, does this sound right to you?

Given that the likelihood of finding an appropriately trained technician is pretty low out here, does that mean that I'd have to ship my ARC integrated to the factory every time I need to replace a tube?

FWIW, I have a degree in Physics and decades of experience working with electronics, so it's hard to believe that something as simple as biasing vacuum tubes can't be done by an experienced user with a voltmeter.

Wow, I didn’t expect that.

Here’s why: Without the ability to audition, my expectations were based on: comments from knowledgeable people like you; trusted reviews; manufacturer reputations; and pricing. One key element was Fremer’s Nu-Vista review -- "the best product that this company has ever produced” — as well as lots of owner comments about the unique sonics produced by nuvistor technology.

The Nu-Vista 800.2, which replaced the 800 model I’m considering, differs primarily in its power-supply design & aesthetics (minimal if any change to the audio signal path). Sure, I know that PSs are critically important in any amplifier, but in my application, the 800’s 330wpc means that my Harbeths -- nominally requiring 25wpc -- will rarely suffer from lack of overhead. And my system includes $10K of power-conditioning. So I suspect that the 800.2’s improvements, wouldn’t be as dramatic in my system as they would in one built around, say, power-hungry Wilsons, or even Maggies.

OK, given all that: The 800.2 is a $22,000 box that probably sounds more like than unlike the 800. The VSi75 is ARC’s mid-performance integrated, normally selling for about $8K; and you & others have said here that, despite sounding more like than unlike ARC’s Reference amps, it’s not in a class sonically with the Ref 75.

So I wouldn’t have been surprised if you’d told me that the Reference 75 boasts clearly superior sonics than one of MF’s $5-10K MX-Series amps. But the VSi vs. the Nu-Vista? I’m not contesting what you say, because your opinion is far better informed than mine. I’m just saying that such an unequivocal statement was a surprise. Your initial comments about not being too familiar with MF products suggest that you might not be taking into account the Nu-Vistas’ reputation for sounding very different than MF’s more popular MX amps. Nonetheless, your comment pushed me far in the direction of going ARC.

But then you brought up another important point that I hadn’t considered. My listening is split pretty much 50-50 between "critical" SACD/phono/hirez streaming stereo and HT multi-channel. Do I really want to "waste" that much tube life watching TV? Maybe tubes are just a poor match for this application. And maybe the VSi is simply not configured to work in a HT Bypass application – no sub out & no bypass input. So am I back to Square One?

I’d originally hoped to find a way to share the Harbeths between two distinct sources: That is, drive them from the AV/receiver when watching TV, but switch them to better-quality electronics for critical listening. I finally gave up. Maybe some speakers have multiple, auto-switching inputs (like my MartinLogan sub), but not the Harbeths.

So since the solution I really need is out of reach, I’ve spent a lot of time trying to shoehorn products like ARC & Pass Labs integrateds into an application they weren’t really designed for.

None of this should imply that this conversation is not very, very helpful. I’ve always wanted ARC in the house, but maybe it’s just not in the cards. So that’s why I’ve been trying to get a fix on what the Nu-Vistas sound like *directly compared to* other products I’m considering. Your above comments are the most helpful I’ve found so far, so thank you again.

The ARC amp will outperform the MF. More real, natural, musical sound. I suppose it depends on how much time you run your HT. Lots of folks run the HT way more than the 2 channel. The start up time is a couple minutes… I have a friend with one… he will tell me exactly next time when he starts his up next time. My Ref 160s is 3.5 minutes.

If your HT is on 8 hours a day and a couple hours for audio only. That is going to cause you to replace the tubes every year. If that is not a problem… the definitely go for it.

My concern would be the difference in character between the center and surrounds given really natural musical sound to the FR and FL and budget solid state to the center and surrounds.

To see where I am coming from look at my virtual systems. My HT is B&W 805 speakers and two subs with Meridian Surround and Rotel 250wpc amp. My main system Sonus Faber speakers and all Audio Reseach components. I have a separate headphone system Aurrender/Ayre/Woo 300b. So I am familiar with the tradoffs.

THe operant word re: HT was "double duty". My legacy components, those I use for "serious" 2-channel listening, will be routed directly to the new integrated, bypassing all HT electronics & cables.

Context: The home theater uses relatively inexpensive $2K Class D amps to power the surround & center speakers; but its FL & FR signals will be sent to a single dedicated input of the integrated. Not yet sure if I’ll route analog FL/FR receiver output directly to an analog input or first pass the receiver’s unprocessed digital output through an external DAC. But there’ll be time to make that decision after I settle on an amp.

Either way, I’ll always drive the front-channel Harbeths with the same higher-quality power amp (and possibly preamp), regardless of whether the source is the existing A/V receiver playing a multi-channel disc or streaming 5.1 movie; or a stereo SACD, LP, or outboard DAC.

Oh, and re: headphones, the MF has a line-level output that would drive my Class A HP amp nicely.  I'm not sure how I'd extract headphone output from the ARC but that's not a dealbreaker for me.

I hope that clarifies things.

But I’m a little confused myself. After recommending the ARC, you cite the MF as the better choice. Was that a typo?

One other thing: I hope you’re not conflating popular MF’s M-series amps with its more esoteric Nu-Vista line. Completely different animals; e.g., the Nu-Vista integrated that just replaced the 800 I’m considering lists for $22,000; with Nu-Vista separates running twice that.

The Nu-Vista line is based on a modern version of 1950s nuvistor technology -- essentially tiny solid-state metal-and-ceramic vacuum-tube-like devices. I’d suggest browsing Michael Fremer’s Stereophile review of the 800 for a quick heads-up if you’re not familiar.

Btw, Mikey’s review contained some of the highest praise I’ve ever heard him give to an amp. In fact, some of his characterizations of the 800’s sound quality seem a lot like those I’ve heard about ARC tube gear. Hence, my original question.

See: https://www.stereophile.com/content/musical-fidelity-nu-vista-800-integrated-amplifier

Anyway, thanks for the reply; I think we were discussing a similar issue earlier this week, and I consider it a real opportunity to be able to discuss ARC gear with someone as knowledgable as you.

But given these clarifications, do you still recommend the MF? Remember that I’m trying to consider only differences in sonics at this point.

I would without question recommend the Audio Research for sound quality. I am very familiar with all their products. Less so with MF… but have read lots. However, since they are going to be part of a tv system… that is a different story. 
 

First headphone jacks out of nearly all, even high quality components are not good… so not much of an asset. Also, if you are talking about 5 channels, the center should be the same speakers, and not of wildly different sonic character from the other channels. 
 

Just as an aside… it is much preferable to separate two channel audio systems from HT if you can. Vastly different objectives and requirements. If I had say $25K for systems… I would put $20K in audio in a separate audio system and $5K in HT. But you may not be able to do this.

So, I guess the MF wins if this is the only two choices. 
 

If there are options… I’d be happy to look at the whole picture. There is a place to put photos and I’d your existing components under Virtual systems. I am 71, so this doesn’t come from a young whippersnapper,