Driving a 275 thru XLRs from a single-ended pre?

[LewinskiH01]

I'm researching purist-design preamps to go with my 275 Mk IV and have come by 3 that, while being dual mono designs, only provide RCA outputs: First Sound Presence, Lamm LL2, Joule Electra LA-150.

The issue is the 275 Mk IV really is better off driven through XLRs to avoid the phase splitter tube and the volume pots...so here goes the stupid question: what's the downside of using RCA-to-XLR adaptors coming out of the pre and driving the 275 from the XLRs?

Feel free to flame me! :thmbsp:

Horacio

 

[nsgarch]

I'm researching purist-design preamps to go with my 275 Mk IV and have come by 3 that, while being dual mono designs, only provide RCA outputs: First Sound Presence, Lamm LL2, Joule Electra LA-150. The issue is the 275 Mk IV really is better off driven through XLRs to avoid the phase splitter tube and the volume pots...so here goes the stupid question: what's the downside of using RCA-to-XLR adaptors coming out of the pre and driving the 275 from the XLRs? Feel free to flame me! :thmbsp: Horacio

Horacio, you already answered your own question *see above. So why hogtie yourself by just considering those three preamps? Good as they are, there are so many others as good and better, that provide both kinds of inputs AND outputs (and XLR inputs are especially nice with CDP's DAC's and the best phono preamplifiers. :yes:

 

[LewinskiH01]

Hey Neil.

Glad you chimed in. You do have a point in regards to sources generally benefiting from XLRs. Yet I have to believe the very good purist designers behind these units had that in mind when they decided to go this route.

So the one purist preamp in my short list that is fully balanced is an Atma Sphere MP3. Only XLR inputs and outputs. Butt ugly too!

You wrote "there are so many others as good and better". Can you recommend some in the $2.5k neigbourhood (used)? I know you advocate solid state preamps. Feel free to recommend SS or tubed.

Horacio

 

[nsgarch]

Hey Neil.

Glad you chimed in. You do have a point in regards to sources generally benefiting from XLRs. Yet I have to believe the very good purist designers behind these units had that in mind when they decided to go this route. I wouldn't make that assumption (you forgot Shindo by the way ;--) And IIRC, Lamm makes pre's w/ BAL connections?
So the one purist preamp in my short list that is fully balanced is an Atma Sphere MP3. Only XLR inputs and outputs. Butt ugly too! If you're the best, no one cares what you look like Remember, the Atma Sphere has fully balance circuit topology (which is what makes it so expensive) but that is not necessary for an amp or preamnp for it to have real balanced connections. The Atma Sphere can have ONLY balanced connections because of its balanced crcuit design.
You wrote "there are so many others as good and better". Can you recommend some in the $2.5k neigbourhood (used)? I know you advocate solid state preamps. Feel free to recommend SS or tubed. Well there is Klyne, Ayre, Mark Levinson, BAT, to name four.

 

[MX117.MC7150]

The MC275 sounds especially nice with the BAT VK-30 (non-SE model to allow for tube-rolling, with 6-pack and remote options). Check listings on Audiogon for preamps. Upscale Audio in CA usually has some excellent deals on BAT preamps.

 

[LewinskiH01]

MX117: thanks for the BAT VK-30 tip! I'll research that pre. Do you know anybody pairing the VK30 and 275? I'd love to get in touch.

OK Neil, you are successfully derailing my thread.:yes: Don't want to get into an argument about your beliefs:thmbsp:. Going back to the point:

what's the downside of using RCA-to-XLR adaptors coming out of the pre and driving the 275 from the XLRs?

Anyone?

Horacio

 

[ron-c]

I would suggest you use unbalanced cables if your preamp only has unbalanced out. The amp will sound fine this way.

Thanks,
Ron-C

 

[MX117.MC7150]

MX117: thanks for the BAT VK-30 tip! I'll research that pre. Do you know anybody pairing the VK30 and 275? I'd love to get in touch. Horacio

I used the VK-30 with the MC275V for over a year. And, it is the one system I wish I had kept (but, I never do). I even ran the system with with a pair of MC275V amps and found that I prefer the sound of a single MC275V to a a pair of them running in mono. The best sounding SS amps have only two (2) output devices per channel (Sony TA-N86B & Bryston 2B-LP) just like the MC275V has only two output tubes per channel. Something magical to my ears about not having to match pairs of output devices. Looking back (too many years and too many systems) it was the best sounding system I've owned. After some tube-rolling, I found the most musical sound came from using a quad of matched Tung-sol reissue 6550s and some NOS RCA and Raytheon small signal tubes in both the VK-30 and MC275V. Here's a link to some VK-30 info. http://www.balanced.com/products/line/Vk-30/index.html

Also, I tried using XLR-XLR, RCA-XLR and XLR-RCA adapters at one and both ends and found the best sound was to simply to go RCA-RCA. I finally settled on a 1m pair of Wasatch (no longer in business) 105-U ICs. I think the XLR-XLR was just a bit deeper in sound-stage than RCA-RCA, but not as realistic in the overall presentation. That is why I suggested you try both.

 

[nsgarch]

MX117: thanks for the BAT VK-30 tip! I'll research that pre. Do you know anybody pairing the VK30 and 275? I'd love to get in touch. OK Neil, you are successfully derailing my thread.:yes: Don't want to get into an argument about your beliefs:thmbsp:. Going back to the point: Anyone? Horacio

OK Horatio, the downside is:
A. You're not accomplishing anything. You'd simply be feeding the balanced inputs (and input circuit) a single ended signal (albeit through a balanced connector), and
B. The amp would probably not meet it's specs (as Ron likes to say) trying to amplify a single ended signal that has not been properly split and inverted.
I don't understand what you meant by "derailing your thread". And besides, you invited us flamers! I think the comments you received from both Ron and MX117.MC7150 are quite relevant. Especially Ron's about using the UNBAL inputs if your preamp only has UNBAL outputs -- I just expanded on that thought a little further in A and B above.

 

[TSmith8605]

Just to further add to what others have said, I have used my C220 and MC 275 IV with both balanced and unbalanced connections with a pretty revealing system with about 15' runs and honestly could not tell much difference. Correct conversion from unbalanced to balanced requires a balun (transformer) or active circuit (with a tube or transistor). The first stage in the MC 275 does that function and does it pretty well.

Unless you have very long runs from the preamp to the amp, I think you should make the balanced / unbalance issue secondary to other considerations with your pre-amp selection. If you find one you like with unbalanced outputs, use it that way. My opinion, YMMV.

BTW, as another option, the C220 is a pretty nice preamp available used in your price range.

 

[LewinskiH01]

Thanks all for the input.

MX117: what speakers were you using with your VK30 + MC275 combo?

Neil: That's what I was looking for. Flames are fine, I knew I was asking something stupid, just didn't fully understand why it was so. The derailing comment was a jokingly way of referring to your comments about moving to other preamps instead of explaining why my question was dumb.

Terry: Thanks for the input too. I'm aware of the C220 as a nice device. The combo with a 275 does sound nice too. While it has XLR connectors, it's not really a balanced design. Also, while it's in my price range, it does have more features than I need and I'm more interested in a purist-type designs were all the money is spent on the few things that matter most to me. It is the option I compare everything else against, though.

Thanks all again.

Horacio

 

[markc2]

I will throw in an EAR 864 or if your lucky an EAR 868. Both can be had for around the price you are looking for, they also have balanced inputs. Not sure if they are truly balanced though.

 

[CruzBay]

what's the downside of using RCA-to-XLR adaptors coming out of the pre and driving the 275 from the XLRs?

From a technical standpoint, only pin 2 on the amplifier would get signal, on those adapters, pin 3 & 1 (low and ground) are usually shorted together.

That being said, they're used all the time in the broadcasting world.

I say try it and listen, losing the inverted portion (the noise cancelling part) may sound better than the phase inversion done in the amplifier.

 

[nsgarch]

From a technical standpoint, only pin 2 on the amplifier would get signal, on those adapters, pin 3 & 1 (low and ground) are usually shorted together. That being said, they're used all the time in the broadcasting world. I say try it and listen, losing the inverted portion (the noise cancelling part) may sound better than the phase inversion done in the amplifier.

Yes, but you wouldn't be providing the amp the BAL signal input voltage it requires in the BAL mode.

In the single ended mode (using the same single ended signal but through the RCA inputs) the splitter/inverter circuit creates the other "half" of the signal, doubling the original voltage in the process.

 

[whoaru99]

While I haven't personally heard one, I do know of the Audio Research LS-5, which is a fully differential/balanced tube preamp. Usually goes for around $2K from what I've seen.

 

[MX117.MC7150]

MX117: what speakers were you using with your VK30 + MC275 combo? Horacio

Yamaha NS-1000, Sony SS-M7, Krell monitors (I've forgotten which, but it is the current model) and settled on the Joseph Audio RM7's I'm using now. When needed, I augment with a powered sub. But not often. And, I listen in the near-field (<6') to remove room interference.