Reference 75

[MylesBAstor]

I doubt it would happen though. I owned the D70 MKII and I heard the REF-75. I know which one sounds better to my ears.

Truly.

All it takes is one listen with the Ref. 75 driving either the $195K or 10 K NOLA speakers!

 

[DaveyF]

Have any of you guys actually listened to a D70Mk2 with newer ancillary gear in the last few years? Or, are you simply relying on an audio memory that is years old. I'm going to try and source a Ref75 to put up against my D70Mk2 and play them both for all to hear. Should be an interesting AB. I think the last person to hear my D70Mk2 was Flez, maybe he could comment.

 

[puroagave]

Have any of you guys actually listened to a D70Mk2 with newer ancillary gear in the last few years? Or, are you simply relying on an audio memory that is years old. I'm going to try and source a Ref75 to put up against my D70Mk2 and play them both for all to hear. Should be an interesting AB. I think the last person to hear my D70Mk2 was Flez, maybe he could comment.

the d70 mk II was my first 'high end' tube amp, i drove maggie IIIa's fairly well with them back in the day - it was ballsy for a 60w amp. schlepp your d70 over to stereo design i can arrange to have kentron or art set up a system for a shoot out.

 

[DaveyF]

the d70 mk II was my first 'high end' tube amp, i drove maggie IIIa's fairly well with them back in the day - it was ballsy for a 60w amp. schlepp your d70 over to stereo design i can arrange to have kentron or art set up a system for a shoot out.

Rob, PM sent.

 

[mep]

Have any of you guys actually listened to a D70Mk2 with newer ancillary gear in the last few years? Or, are you simply relying on an audio memory that is years old. I'm going to try and source a Ref75 to put up against my D70Mk2 and play them both for all to hear. Should be an interesting AB. I think the last person to hear my D70Mk2 was Flez, maybe he could comment.

I listened to it with the Convergent Audio SL-1 MKII that I used to own which is the same preamp that you own (or yours may be a generation behind). The D-70MKII is a very nice sounding amplifier. It will not have the bass quality and extension of the newer ARC amps. The VT-100 MKII would smoke the D-70 and the VS115 is just in another league entirely. The REF 75 has a bigger power supply than the D-70 and it has the KT-120 tubes which I think give the best bass compared to the usual contenders (6550/KT-88).

 

[KeithR]

I listened to it with the Convergent Audio SL-1 MKII that I used to own which is the same preamp that you own (or yours may be a generation behind). The D-70MKII is a very nice sounding amplifier. It will not have the bass quality and extension of the newer ARC amps. The VT-100 MKII would smoke the D-70 and the VS115 is just in another league entirely. The REF 75 has a bigger power supply than the D-70 and it has the KT-120 tubes which I think give the best bass compared to the usual contenders (6550/KT-88).

What about midrange?

 

[DaveyF]

What about midrange?

That's a great question, Keith. Since the power output of the two amps is similar and the the D70Mk2 is well known as having one of the greatest midranges, I'm thinking this is where the D70 will prevail. I love how mep states above that the VT100Mk11 would smoke the D70Mk2.....since it wasn't "smoked" by a VT100Mk3 in an AB that our group conducted about a year ago. Instead, the owner of the VT100Mk3 was so amazed at what the D70Mk2 could do, he sold his VT100Mk3 and bought M100's. BTW, If you were to ask Ken Stevens which tubes he prefers...the new KT-120's or Winged C6550's...you will get an interesting answer! ( Hint, it isn't the newer tube) BUT then again, what does Ken know
Like I implied in my other thread, IMHO to give an opinion on an amp that one hasn't heard in another's system and in how long, is foolhardy at best!

 

[mep]

That's a great question, Keith. Since the power output of the two amps is similar and the the D70Mk2 is well known as having one of the greatest midranges, I'm thinking this is where the D70 will prevail.

So how many people said the D-70 MKII has one of the "greatest" midranges? How many years ago was that? Was that back in the 1980s? And let's say that for some reason you feel that your mighty D-70 MII has a better sounding midrange than the REF 75 but loses everywhere else, does that make you *win*?

I love how mep states above that the VT100Mk11 would smoke the D70Mk2.....since it wasn't "smoked" by a VT100Mk3 in an AB that our group conducted about a year ago.

I have never heard a VT-100 MKIII and don't know how it differs sonically from the MKII that I owned. I also don't know how old the tubes were in the MKIII you did the comparison with and how long it had been since they were biased and if they were biased properly. The VT-100 series were another biasing nightmare brought to you by ARC. You practically have to disassemble the amps to bias them and if you don't bias the input tubes correctly your output tubes will never operate correctly. Kevin Deal from Upscale Audio will not sell any tubes for any of the VT-100 series amps because he knows how wacky the bias scheme is and what the chances are that regular customers could come close to setting them up properly, ruining the new tubes, and blaming him.

Instead, the owner of the VT100Mk3 was so amazed at what the D70Mk2 could do, he sold his VT100Mk3 and bought M100's.

That makes perfect sense that if your friend liked the sound of your D-70 MKII amp better than the sound of his VT100 MKIII amp that he would go for a pair of M100 amps. The M100 amps have the same type sound as the D-70 except they have more power, they are monoblocks, and they are much easier to bias than the D-70 while keeping that house sound ARC had back in the 1980s. Part of that sound is the 6550 series regulator tube used in the power supply. Using a 6550 regulator tube was a scheme that ARC used for years, and then they went away from it, briefly came back to it, and have since abandoned it. The M100 amps are still sought after and their price is increasing.

BTW, If you were to ask Ken Stevens which tubes he prefers...the new KT-120's or Winged C6550's...you will get an interesting answer! ( Hint, it isn't the newer tube) BUT then again, what does Ken know

Big deal that Ken Stevens doesn't like the KT-120 tubes. ARC and CJ both switched over to them, but hey, what do they know about designing tube amps?

Like I implied in my other thread, IMHO to give an opinion on an amp that one hasn't heard in another's system and in how long, is foolhardy at best!

I gave my opinion based on owning the D-70 MKII and having it in my system, not yours or someone else's system. I hope you follow through with Rob and cart your D70 off to the high-end shop and have your little throw-down at the hoe-down and report back with your findings. I'm more interested in hearing the opinion of others who will be there because I'm pretty sure you already have your mind made up. Your speakers of choice don't have much bass and are more midrange oriented and since you love the midrange of the D70, that's a great choice for you and your system. I get why you like it. I do believe that when the D70 is hooked up to a speaker that is more full range than yours, the advancements of the newer ARC amps will shine through. I for one will be amazed if the REF 75 doesn't eat your D-70 for lunch from top to bottom.

 

[dafos]

Quick question gentlemen: How can I connect the REF 75 to my (futur) REF DAC if the balanced XLR Analog output of the REF DAC is already used to connect my balanced Headphone Amp to the REF DAC ?? I have a pair of XLR-Out missing !

You hit it right on the head, you need an extra balanced output that is only present in the arc line stages. Since I assume you don't listen to headphones and your speakers simultaneously, just connect the amp or the headphone depending on what you are listening to at that given moment. Or you can buy a ref line stage and enjoy the benefit of twin balanced outputs.

 

[rblnr]

I know that some people including Carl Marschiotto of Nola like the 75 better than the 150.

 

[mep]

I know that some people including Carl Marschiotto of Nola like the 75 better than the 150.

Probably because it's easier to keep two output tubes per channel reasonably matched and biased correctly than it is with 4 or more per channel. The REF 75 just hits a sweet spot on both power, simplicity of a single pair of output tubes per channel, and looks. It may well be one of the best looking amps that ARC has ever made. And, it will be easier to maintain the proper bias than scads of other ARC designs.

 

[KeithR]

Probably because it's easier to keep two output tubes per channel reasonably matched and biased correctly than it is with 4 or more per channel. The REF 75 just hits a sweet spot on both power, simplicity of a single pair of output tubes per channel, and looks. It may well be one of the best looking amps that ARC has ever made. And, it will be easier to maintain the proper bias than scads of other ARC designs.

Have you heard it Mark? It appears to use less negative feedback than the 150, which may result in folks preferring it over the 150.

http://www.stereophile.com/content/audio-research-reference-75-power-amplifier-measurements

 

[mep]

Only at RMAF and Axpona. I think it sounds great.

 

[microstrip]

Have you heard it Mark? It appears to use less negative feedback than the 150, which may result in folks preferring it over the 150.

http://www.stereophile.com/content/audio-research-reference-75-power-amplifier-measurements

Keith,

There are so many and so large differences between the two amplifiers that I that I think we can not be sure that the sound differences are due to the small difference in negative feedback (1dB). I heard it once, but without direct comparison in my system I will not risk an opinion.

 

[KeithR]

Keith,

There are so many and so large differences between the two amplifiers that I that I think we can not be sure that the sound differences are due to the small difference in negative feedback (1dB). I heard it once, but without direct comparison in my system I will not risk an opinion.

I'm not sure how much is used in either, but do note the rising distortion vs frequency which is a function of it's use. however, distortion vs output seems more smooth in the case of the 75, which is why I assumed it uses less feedback- i coudl be wrong.

 

[TommyTunes]

I've been looking at the ARC Ref150 to drive Wilson Sophia3's but I like the Ref 75 anyone know if this amp would be a good fit with the Sophia's?

 

[jap]

HP's REF 75 review:

http://www.hpsoundings.com/2013/12/...ampaign=audio-research-reference-75-amplifier

The REF 75 also got Stereophile's Products of 2013 Joint Amplification Components of the Year Award:

http://www.stereophile.com/content/stereophiles-products-2013-joint-amplification-components-year