Pass amp paired with audio research pre?


 Wondering if anyone has had experience matching a pass labs amp with an audio research preamp. Do they make a good combination?  Thinking  about audio research reference 5SE matched to one of the X series pass amps. I have Harbeth 401.2 speakers...kind regards 
9be03082 a015 4313 a5c2 299d9a7c3034fanotunes
My current amp is a music reference rm-100. 

I also have a newly refurbished Harmon Kardon Citation 2. Haven’t had the chance to listen to it yet…
@fanotunes
Any particular reason the preamp has to be ARC?


ARC does not recommend driving an amp with less than a 30K input impedance. Pass Lab X series amps are lower than that (22,000 ohms according to their owner's manual), so bass will suffer and distortion will be higher.

If I were you I would look elsewhere. There are balanced tube preamps out there that have no problem driving Pass Labs amps at all and as a result IMO sound better as well.


There is a standard for balanced line operation (a.k.a. 'AES48'). The standard is there to insure that balanced sources will work with balanced inputs on things like power amps. Most high end audio preamps don't support the standard; not sure if they don't know it exists or simply chose not to. But in a case like this it makes a difference- if ARC supported the standard then you could just plug and play. There are tube preamps that support the standard.


Another aspect of the balanced standard is that it is effective at eliminating interconnect cable artifacts. If you've ever heard two cables sound different, or heard of that phenomena, you know what I'm talking about. This means you don't have to spend a lot of money on the cable and you can run it much longer distances, although you get the benefit of balanced operation even if the cable is only 6 inches.


In case you think I'm slamming ARC I'm not; you were asking about whether it would work. They are not alone in not supporting the standard. I can't think of a good reason why not (sound quality isn't one of them) unless it was just too hard to do, something like that.
The .8 series lists 50/100k input impedance.  A big increase over the previous series.

I felt comfortable running a Cary SLP05 into an xa30.8.  The Cary lists a low output impedance, but was measured at some point to hit 3400 at 20hz.  I like the combo with neutral speakers, but I have different issue with way too much gain.



I just sold an ARC Ref 3 that I used with a Pass Xa-25.  It was boring on rock, decent on jazz.
Thank you for the response!

boring on rock? Audio research can seem a bit thread bare sometimes. Is that what you’re referring to?
Thank you for the response!

boring on rock? Audio research can seem a bit thread bare sometimes. Is that what you’re referring to?
boring on rock? Audio research can seem a bit thread bare sometimes. Is that what you’re referring to?
No.  Too laid back.  I use a REL s/5 to fill in the bass.  
Gotcha. Attributed to amp or preamp?
Definitely the pre.  I'm using a Herron VTSP 360 now.  Only about 30 hours in and things are sooo involving.  The Xa-25 is super transparent. 

Pass amp paired with audio research pre?

 Wondering if anyone has had experience matching a pass labs amp with an audio research preamp. Do they make a good combination?
I think it will work great, just make sure the "output impedance" of the AR preamp is at least 10 x lower than the "input impedance" of the Pass amp. (Some Pass amp can be too low for many pre's) .

Cheers George

Pass amp paired with audio research pre?

 Wondering if anyone has had experience matching a pass labs amp with an audio research preamp. Do they make a good combination?
I think it will work great, just make sure the "output impedance" of the AR preamp is at least 10 x lower than the "input impedance" of the Pass amp. (Some Pass amp can be too low for many pre's) .

Cheers George
I think it will work great, just make sure the "output impedance" of the AR preamp is at least 10 x lower than the "input impedance" of the Pass amp.
The thing to look at is the output impedance at 20Hz, which is often considerably higher than it might be at 1KHz.
@fanotunes, did you mean to say you currently have an RM-200? I’ve never heard of an RM-100! It, like the Pass amps, has a relatively low input impedance: 20k single-ended, 30k balanced.
The thing to look at is the output impedance at 20Hz, which is often considerably higher than it might be at 1KHz.
I didn’t think AR would "cheap out" on output coupling caps that are too small into anything above 10k.

As this infers they have 10uF output coupling cap. Plenty large enough even into 10kohm power amp which would be -3db @ 1.5hz!! plenty low enough.
20k amp like some Pass’s would be -3db @ 0.75hz!!!!!
"Stereophile review: During shipping, one of the four large, 10µF Teflon output-coupling caps at the right rear of the printed circuit board had broken off. ARC sent me a replacement"

Atmasphere: 

 Thank you for your note! Hypothetical. Trying to think about where I should go with future purchases. I live in the sticks. Not much opportunity to listen to other components. I try to read and ask questions.

Been thinking about audio research reference 5SE, Audio research reference phono 3, pass labs 250.8. 

I have a VPI classic 4 with a transfiguration Proteus cartridge…

bdp24:

  My bad! I have an older model RM 200. I fell in love with Music reference amps early on.

Feeling like my system is a bit too polite. Wonder if my speakers could use a kick in the pants from a solid-state amp. Love their organic sound though.

I listen to very little heavy metal. More 60s and 70s rock,  grateful dead, traffic, Fairport convention, Joni Mitchell, ...fair bit of jazz and classical. Do occasionally throw on some Steve Miller, the cars, the police, REM, from my high school and college days…

 Wonder how much of this politeness I can attribute to my audio research LS-16
fanotunes OP
Been thinking about audio research reference 5SE, Audio research reference phono 3, pass labs 250.8.
This AR pre is what my figures were based on above, and this would be a fine match, with the Pass amp.

Cheers George
Post removed 
Ref 5 into a Pass X350. The X350 input is actually in parallel with a crossover used to run an SVS sub. So load on the Ref 5 is about 15k ohms. I think you'd have to go below 10k to really start seeing any degradation in response or output.

I think the ARC/Pass combo will give you the best of both worlds. Plus you can run the whole thing balanced and it's hard to beat the versatility of the AR preamps.

Audio Research has been changing output caps over the last few years so while I doubt they would go cheap some may have a different output impedance than others.

So load on the Ref 5 is about 15k ohms. I think you’d have to go below 10k to really start seeing any degradation in response or output.


Like I said above the AR Ref5 will have no problem. It’s 300ohm SE or 600ohm BAL outputs, and into 20k amp that’s no problem at all, and the coupling caps at 10uf and are fine down to -3db at 0.57hz also.

Worst case the AR Ref5 would be fine even seeing an amp load down to 3k SE or 6k Bal and the 10uf cap into the 3k would be still be only -3db at 5hz still ok.

Cheers George

@fanotunes, Tim deParavicini's EAR-Yoshino electronics don't get much love here (though they do elsewhere, including at Positive Feedback by Robert Levi, and in the UK press, especially Ken Kessler in HFN&RR. Ken loves Tim's stuff), but his 868 and 912 pre's are designed to drive a 600 ohm load. Paravicini does a lot of work in pro studios (including Pink Floyd's), where 600 ohms is the standard.

Those pre's have no trouble driving a 10k ohm power amp input. They also are fine sounding, the 868L being noticeably better imo than the ARC LS-16 (I've had both). It had better be, costing over twice as much new, and twice as much used! It is a pure-tube design, the LS-16 a ss/tube hybrid (as are all the LS models). By the way, your RM-200 is called by some a hybrid design, because of it's bipolar input stage (the driver and output stages pure tube), which po's Roger Modjeski. But that's a story for a different thread ;-) .

 Thank you, everyone, for the responses. Sorry for the late reply. I’ve been traveling for the last two days ( 23 hour drive from Spencer, Iowa to Beaufort, North Carolina! )

 Thank you for the discussion regarding input and output impedance. I learned something there! 

monoogan: 

If I understand correctly, you were running an x350 with a ref 5.  No issues with impedance.  What sort of music do you listen to? And how does it sound? What sort of speakers do you have? 

I really hope moving from the LS 16 to the Ref 5 will solve my concerns as i’ve always liked my Music Reference.  If not, a Pass amp may be the next step.

My system seems just a bit too polite. Right now, I am attributing that to the LS 16. If not that, thinking a more powerful  solid-state amp will help.

Could also be the transfiguration proteus as it seems pretty laid back too...?

@fanotunes, I would attribute the lifeless sound you hear to the LS-16 before the RM200 (I've owned both, and dumped the 16). Check into how ARC creates the balanced XLR outputs on the LS-16. Since the RM200 has true balanced inputs, you may as well feed it a true balanced signal (though it will accept unbalanced without modification or sonic penalty, says Roger Modjeski). In his EAR 868 (and in the 912), Tim deParavicini creates that pre’s balanced outs by way of transformers (standard in recording studio equipment). Though I don’t know it to be true, it may be that ARC does so with opamps, which is very common in consumer gear.
Why not pair a Pass pre with the Pass amp? Both are excellent pieces of equipment and should match well.
Thank you for your note.  Obviously an option to consider as well.  Had thought to stick with the tube preamp. Like the audio research stuff. But certainly in option to consider as well
Bdp24:

I suspect you’re correct. The LS 16 may well be the culprit.  The reference 5SE is supposed to have a more dynamic sound, and will hopefully resolve this for me. 

 Markcdaniel makes a good point in that may have to get away from the audio research preamp altogether. Audio  research does have its house sound which can be a bit un-involving at times.

 I have read some good reviews of the Ear products but have never actually listened to any.

 Trying not to add too many variables to the mix. Trying to take an incremental approach...?
Thank you for your note! Hypothetical. Trying to think about where I should go with future purchases. I live in the sticks. Not much opportunity to listen to other components. I try to read and ask questions.

Been thinking about audio research reference 5SE, Audio research reference phono 3, pass labs 250.8.

I have a VPI classic 4 with a transfiguration Proteus cartridge…
@fanotunes
If you are thinking about solid state Pass Labs is a very good choice, but since you already have the RM200, I see no point in changing out the amp- the RM200 is pretty neutral so I would not think for a moment that is is responsible for the excessive laid back quality.

Before changing anything out, I’d consider replacing the tubes in the line stage and possibly the input tubes of the amp. Its common if those tubes get weak for the preamp or amp to get a bit ’sleepy’- which might be easily described as ’too laid back’. You may find no need to do anything else once that is done!


After making sure those tubes are not an issue, I would then investigate the phono cartridge loading. The loading is there for the preamp, not the cartridge- its meant to prevent ultrasonic or RF resonance inherent in all pickups from messing with the preamp. The correct loading (if the preamp is sensitive to RFI; ours are not so no need for the loading with LOMC cartridges;) is the **highest** value that prevents the resonant circuit caused by the cartridge inductance and the tone arm cable capacitance from going into excitation. Since each cable is different (and thus the capacitance is not predictable), cartridge manufacturers make worst case recommendations; this can result in a duller presentation, since the loading resistor means the cartridge has to do more work. This in turn results in a stiffer cantilever that is less able to trace high frequencies. That is why its advantageous to work with a preamp that does not have the RFI sensitivity in the first place- and then no need for a loading resistor.




Audio  research does have its house sound which can be a bit un-involving at times.

Your situation sounds similar to my own.  I've been there, done that.  I spent several years trying to eliminate that lifelessness.  After replacing my speakers, turntable/arm and power amp the sound was a different lifeless.  I got down to my least suspected components - ARC PH-7 and Ref 3.  Jumping ship to another brand was a revelation.  I know people love ARC.  I did.  Things change.
ARC owners can sometimes resemble owners of Linn ;-) .
For those of you here who claimed that ARC house sound is uninvolving I would have to disagree with that broad general statement. You should have a listen to the ARC Reference 10 linestage preamp and other Reference series power amps such as the Ref 750 SE vacuum tube monoblock amps. Perhaps the entry level and lower end ARC products might not sound as involving as their Reference series gears. I have only listened to their Reference series gears such as the Ref 10 linestage pre and couple different Reference series models of power amps such as the Ref 750 SE vacuum tube monoblock amps and the newest latest Reference series monoblock amps that were introduced recently (can’t remember model number). So I can’t say for their lower end or entry level series products.

In regards to some of the comments made here about the so-called house sound of a particular brand, I would have to disagree with that. that’s a generalization based on insufficient evidence and facts. The so called and mentioned house sounds might have been attributed by some other components in the chain eg speakers, front end source components (both digital & analog), cablings, etc, etc.
There are so many contributing factors that some people came up with their own conclusions and called it a "house sound".
@bdp24 

ARC owners can sometimes resemble owners of Linn ;-) .

In regards to your statement above, that is not true at all. Not sure what you meant by that. 
I have owned Linn products in the past and currently own ARC Reference series gears.

I anticipated that observation might ruffle a few feathers ;-) . Further evidence ;-) ;-) .
For my part, I’ve owned a VT 100 mk II, a SP 10, a LS 16, a phono 5, ...  i like my ARC stuff but must admit I find, and general consensus is, they definitely have a somewhat ‘buttoned down’ house sound. Like they’re afraid of being accused of sounding tubey or something.

 For me, I like it because it puts the music on display rather than showing off artifacts introduced by the component manufacturer.  At the same time, it certainly shows off changes in components up and down the line. 

Sometimes I wish I had more snap and thump.  Sometimes I wish they were a bit more forward. But for what I listen to, I think they do a pretty good job. 

 That does not keep me from getting that ‘itch’ to try something new every now and again.

I’d love to have the chance to own, or even have some extended listening time with, a reference 10,…but right now,  I think I’ll concentrate more on paying off the house ...
Fanotunes, use a Pass preamp and get an ARC phonostage.
I dumped my vinyl pursuit a couple years ago, so I have 0 skin in the game, when commenting on phono pre’s, but Harbeth + Pass I will say is quite epic.  I too was reviewing ARC pre’s, and ultimately settled on a XP-20.  I did not A/B them, so I’m of little use on that commentary, as well.  I will say that the pass chain, to a set of Super HL5 pluses is quite rewarding.  The best way I’m able to put it, Instruments sound exactly like instruments.  
Not to turn the conversation, but I have a don Sachs 6sn7 preamp going into a pair of first watt f4s and it is definitely not boring. It improves the signal from my dac in every way without being syrupy or tubey at all.  You can read about it in my systems page.
Sorry I'm late.

The Ref5 has two parallel outputs. One connects directly to the X350 which drives a pair of Martin Logan Ascent ES hybrids. The second output goes to a dbx 223XL which drives a single SVS PC Ultra. The 223 is just used as a low pass filter, the SVS crossover is bypassed. The Ascents are run full range. This is all done with XLR balanced lines.

We pretty much listen to anything. For awhile it's acoustic blues, then funk, then prog rock and lately western swing. We also use it for movies (love the processor bypass). The music stick in my car has everything from Asleep at the Wheel to ZZ Top.

It's not polite sounding. It'll do Tower of Power the way it was meant to be done. It's very detailed and can go reasonably load before the panels start to compress. eally harsh and compressed recording sound really harsh and compressed.