Parasound Halo P 5 Stereo Preamplifier Preview

[admin]

Looking around at some of the high end two channel offerings available today, it's quite possible you'd think that the zenith of stereo reproduction would be represented by a bare bones analog preamplifier fronted by a fine turntable, feeding a power amplifier, which in turn powered a pair of loudspeakers. While such a system can sound quite good, the fact remains, this is 2013, not 1973. The advent of digital audio and bass management has changed the landscape of audio significantly, and for the better. Fortunately, not all manufacturers opt to stick their head in the sand, case in point Parasound with their new P 5 stereo preamplifier. Priced at $950 and boasting three digital inputs (USB, coaxial, and optical) as well as analog bass management, the P 5 preamp appears to have what it takes to be the brains of a modern, high end two channel system. How does it stand up to a first glance by the Audioholics? Read on to find out.

Discuss and Read the Parasound Halo P 5 Stereo Preamplifier Preview

 

[macddmac]

The link doesn't work.. At least for iPad

 

[haraldo]

Again, thx Steve

Mind you guys, of course we are here looking at bass management in the analog domain, not digital!
Strange thing that there is a SINGLE xlr sub-out, they only provide balanced output for one subwoofer, maybe there is a space constraint issue somewhere, weird, this is....
Well there is single ended sub outs, but why have only one balanced sub-out if the amp is fully balanced all around?

It seems like there is no control of phase on sub-out, of course you will manage if you do have this in the sub-amp but then again why include crossovers and claim that the amplifier provides full bass management if there is no phase adjustment, beats me

 

[gene]

Well there is single ended sub outs, but why have only one balanced sub-out if the amp is fully balanced all around?

As mentioned in the article, the P 5 preamp is a single ended design with balanced connectors. It's not a fully differential design topology.

 

[haraldo]

As mentioned in the article, the P 5 preamp is a single ended design with balanced connectors. It's not a fully differential design topology.

Aha, thx, then I missed that part and .... then it's strange why they provide XLR output's really....

 

[gene]

Aha, thx, then I missed that part and .... then it's strange why they provide XLR output's really....

This is the case with many preamps. You have to look very carefully if the design employs fully complimentary circuitry throughout the entire design. Most don't unless your dealing with upper echelon gear.

 

[haraldo]

This is the case with many preamps. You have to look very carefully if the design employs fully complimentary circuitry throughout the entire design. Most don't unless your dealing with upper echelon gear.

To be honest, it's a bit cheating the customer, isn't it.......?

I heard it from a manager of a major hi-end shop here that sometimes they sell single-ended amps with XLR-outputs, telling the customer they will have no benefits from this as it's single ended design.... but still some people want XLR outputs .... In this case... what for, I ask?

From another side, the Krell KAV-400xi integrated amp that I have is fully balanced all through, but only contains single-ended pre-out .... but in that case it's probably a space constraint on the back panel

 

[Irvrobinson]

To be honest, it's a bit cheating the customer, isn't it.......?

I heard it from a manager of a major hi-end shop here that sometimes they sell single-ended amps with XLR-outputs, telling the customer they will have no benefits from this as it's single ended design.... but still some people want XLR outputs .... In this case... what for, I ask?

Balanced cables are still a value-add for long cable runs, as it provides common mode rejection for noise and distortion induced on the cables themselves. Some installations, especially the custom, built-in sort, need runs of well over fifty feet. The use of fully differential circuitry in a pre-amp and even amplifiers is actually of dubious benefit, more for bragging rights than audible differences, while long runs of single-ended cables can have more real-world problems.

 

[PENG]

Balanced cables are still a value-add for long cable runs, as it provides common mode rejection for noise and distortion induced on the cables themselves. Some installations, especially the custom, built-in sort, need runs of well over fifty feet. The used of fully differential circuitry in a pre-amp and even amplifiers is actually of dubious benefit, more for bragging rights than audible differences, while long runs of single-ended cables can have more real-world problems.

I have to agree. I noticed that most lab measurements on HTM shows slightly better SN numbers with unbalanced, even when the unit tested was truely differential from one end to the other. Presumably the cable runs under those test conditions were kept short. In theory for short runs, either way is good.

 

[haraldo]

If we open this discussion here with single-ended vd balanced and if you can hear the difference we will end up in never-never land, I am tempted but I'm gonna keep my mouth shut about this

I do see Irv's point with long cable runs and I'm sure he's correct on this

 

[Adam]

Steve, I enjoy your articles quite a bit. IMO, though, the "Performance" section should be renamed to "Specifications" or the like. Speculating on performance seems a reach for a preview...as is any discussion of build quality on an article that's never been handled or even seen in person. It's pretty much an opinion piece based on internet info, right?

 

[Steve81]

Steve, I enjoy your articles quite a bit.

Thanks

IMO, though, the "Performance" section should be renamed to "Specifications" or the like. Speculating on performance seems a reach for a preview...

I'll brood on that one, though the specifications I'm looking at in that section are all performance related. Perhaps "Performance Specifications" or some such...

as is any discussion of build quality on an article that's never been handled or even seen in person.

In this case I noted it as "Presuming build quality carries over from its Halo siblings, overall build quality is likely to be quite good, albeit not quite in the "cost no object" category", so there's no actual hands on, just an educated guess based on other equipment from the family I have seen/handled.

It's pretty much an opinion piece based on internet info, right?

More or less. I'd like to think it's at least a marginally educated opinion though

 

[Adam]

I'd like to think it's at least a marginally educated opinion though

Oh, I wasn't questioning that part of it.

 

[gene]

If we open this discussion here with single-ended vd balanced and if you can hear the difference we will end up in never-never land, I am tempted but I'm gonna keep my mouth shut about this

I do see Irv's point with long cable runs and I'm sure he's correct on this

As a telcom engineer for 7 years prior to doing this website full time, I can tell you all things being equal, fully differential designs are ALWAYS superior to single ended. It's not just for noise immunity but for reduction of distortion too. When I designed analog front ends of modems, we needed huge amounts of SNR and low distortion in order for the transmitters/receivers to work. Every design was fully differential for that very reason. Only in home audio do things tend to get dumbed down either for cost purposes or b/c the consumer marketplace isn't properly educated.

That being said, single ended preamps/amps can still sound great but if you're truly pursing the best, you go for fully differential designs, PERIOD!

 

[slipperybidness]

Balanced cables are still a value-add for long cable runs, as it provides common mode rejection for noise and distortion induced on the cables themselves. Some installations, especially the custom, built-in sort, need runs of well over fifty feet. The use of fully differential circuitry in a pre-amp and even amplifiers is actually of dubious benefit, more for bragging rights than audible differences, while long runs of single-ended cables can have more real-world problems.

So, even if the pre isn't fully differential, there is a benefit to XLR? Doesn't this meant he XLR is technically single ended and not balanced (therfore I would not expect a benefit)?

I'm asking to get a better understanding, I haven't had much XLR or balanced experience.

Perhaps a schematic of true balanced XLR vs the P5 XLR would help to visualize the difference here? I may need to use the google.

 

[haraldo]

As a telcom engineer for 7 years prior to doing this website full time, I can tell you all things being equal, fully differential designs are ALWAYS superior to single ended. It's not just for noise immunity but for reduction of distortion too. When I designed analog front ends of modems, we needed huge amounts of SNR and low distortion in order for the transmitters/receivers to work. Every design was fully differential for that very reason. Only in home audio do things tend to get dumbed down either for cost purposes or b/c the consumer marketplace isn't properly educated.

That being said, single ended preamps/amps can still sound great but if you're truly pursing the best, you go for fully differential designs, PERIOD!

It's what I think too, but I didn't want to start the discussion... again.

It's my clear opinion that the Krell KAV-400xi (which is a fully differential design) works better when it's gets it's input from truly balanced sources, as opposed to single ended sources...
I don't know why and what the issue is but it's clearly unmistakably "more grain" when going single ended, it's just more natural sounding.... going fully balanced (source being a benchmark DAC1)

EDIT: As I now hear the DAC1 is not fully differential, but there's still an audible difference by running single ended vs balanced onto the Krell KAV-400xi, I have no idea why.... I would really like to know, though

 

[gene]

So, even if the pre isn't fully differential, there is a benefit to XLR? Doesn't this meant he XLR is technically single ended and not balanced (therfore I would not expect a benefit)?

I'm asking to get a better understanding, I haven't had much XLR or balanced experience.

Perhaps a schematic of true balanced XLR vs the P5 XLR would help to visualize the difference here? I may need to use the google.

Usually they use a differential input op-amp and then convert to single ended. Depending on grounding scheme, its possible to get some noise immunity benefits but not lower distortion.

 

[Irvrobinson]

As a telcom engineer for 7 years prior to doing this website full time, I can tell you all things being equal, fully differential designs are ALWAYS superior to single ended. It's not just for noise immunity but for reduction of distortion too. When I designed analog front ends of modems, we needed huge amounts of SNR and low distortion in order for the transmitters/receivers to work. Every design was fully differential for that very reason. Only in home audio do things tend to get dumbed down either for cost purposes or b/c the consumer marketplace isn't properly educated.

That being said, single ended preamps/amps can still sound great but if you're truly pursing the best, you go for fully differential designs, PERIOD!

High performance networking equipment is one thing, but even the measurements don't point to the superiority of fully differential designs in home audio equipment on a consistent basis, no less audible differences. I admit to looking askance at equipment that isn't fully differential, because we all know that in theory one can always do better with differential rather than single-ended circuitry, but then you look at the measurements and you wonder if it's worth it for audio.

For example, I hesitated before ordering a Benchmark DAC1-HDR a couple of years ago because it didn't appear to be a fully differential design, I intended to use it with fully differential amplifiers, and it was replacing the fully differential Levinson No39. Looking at the measurements from the Audio Critic and Stereophile I had to ask myself, what possible advantage could differential circuitry offer? Almost every artifact was measured at -110db or lower. When I purchased the Levinson in the 1990s I was convinced that the fully balanced nature of the No39 played a role in my strong preference for it over competing CD players and preamps (the No39 is a transport, DAC, and pre-amp in one chassis), but now I'm thinking that advances in IC designs have made topological considerations secondary for line-level audio equipment.

I have no idea if the P5 will measure as well as the DAC1 on the analog outputs, and I probably wouldn't buy it without seeing measurements. Recently I've been wondering about the value of fully balanced power amplifiers too, where I thought there might be an audible difference. As much as I try to hear a difference between my fully differential amp and a model from the same manufacturer that isn't fully differential (which I use for a secondary system), I can't. There isn't even an idle noise difference. I understand wanting every possible practical design advantage, and I think that way myself, but it is a tenuous argument.

 

[Irvrobinson]

So, even if the pre isn't fully differential, there is a benefit to XLR? Doesn't this meant he XLR is technically single ended and not balanced (therfore I would not expect a benefit)?

There is still a benefit to using XLR (balanced) cables, as I mentioned. The question here is simply where in the signal path you are taking advantage of common mode cancellation, in the electronics, in the cables, or over the entire end-to-end signal path. Clearly, as Gene states, there is a theoretical advantage to using balanced circuitry end-to-end. In real-world, line-level audio components, as I just posted, I'm less sure that the difference in the electronics is measurable.

 

[gene]

There is still a benefit to using XLR (balanced) cables, as I mentioned. The question here is simply where in the signal path you are taking advantage of common mode cancellation, in the electronics, in the cables, or over the entire end-to-end signal path. Clearly, as Gene states, there is a theoretical advantage to using balanced circuitry end-to-end. In real-world, line-level audio components, as I just posted, I'm less sure that the difference in the electronics is measurable.

Comparing two identical circuits, one being single ended, one being fully differential, it's very easy to measure a difference in noise and distortion. It's a very trivial matter actually. Audibility is another story however.

I recommend reading this article I wrote many years ago:
http://www.audioholics.com/audio-video-cables/balanced-vs-unbalanced-interconnects

Anyone truly interested in the topic should pick up a copy of: Noise Reduction Techniques in Electronic Systems by Henry Ott.