Peachtree GAN400 Amplifier Review

[GXAlan]

It’s not my money, but my vote is to keep the Powercube. I personally have had two better than -100 dB SINAD 1 kHz amps where running a speaker load (Studio 530) and measuring things electrically showed one amp to have worse distortion that correlated with a tough part of your impedance curve.

 

[Mojo Warrior]

I see a trend in this product brand. They consistently over-promise and under-deliver. Not to mention over-priced.

Sad

 

[anmpr1]

It is an eval unit. Have to decide if I am purchasing it. Will probably do a stand-alone review for it.

An unexpected but happy surprise. FWIW, Peter Aczel had one. For reasons I never found out (I never asked him) it evidently went south on him. I don't know if he ever got it fixed, or what he did with it, but shortly thereafter he stopped reviewing. I think due to health reasons.

I know it is a very expensive instrument and would certainly make a positive addition to ASR investigations. However I'd be looking at warranty and service before making any major cash outlays. As with anything.

 

[Multicore]

You understand, but maybe partially. One power amplifier (or second channel of the DUT) sends current to the DUT output. I think it should be easy to understand. Sine sweep is sent from driving channel and response measured at the output of the DUT (forced) channel. At DUT, 1V = 1ohm, because 1A x 1ohm = 1V.

View attachment 271622

Now that's the ingenious part of the word engineering. Thanks for explaining. The "a) A sinusoidal current source" is provided by another audio power amp, perhaps similar tot he DUT, and "of internal impedance at least 10 times the expected value of the output source impedance is connected ... to the output terminals of the amplifier" 10 ohm should be plenty.

Presumably this has been standard practice since forever but, as I've never been involved in amp engineering, it's new to me.

It's a good day to be reading ASR. Thanks @pma

 

[RandomEar]

Funny thing is that the same company offers a better or similar specd and also powerful one at 1000$ less!
What would be the discriminator for someone to choose this over the cheaper one?

Obviously, this one says "GaN" on the front plate and the cheaper ones don't!

 

[peniku8]

Frequency response is disappointing as it shows load dependency:
View attachment 271534

@amirm Would it be a hassle to align this type of graph's 1khz level to 0dBr? I think that would improve its readability a bit. I checked the 8R graph's 20khz level and saw it at +1dB, but actually it's +0.5dB because the regular passband is at some +0.6dB.

As for the amp, that's a 1.5dB difference at 20khz between 4R and 8R, that's... not ideal...

 

[Gadgety]

Very, very pleased to see the power cube. This is great knowledge in making amplifier selection. Amir, you need to retest a lot of amplifiers!

 

[Gadgety]

Yeh, it is pretty bad. Alas, it was written by AP and it has no other choices whatsoever. I can export the data though and plot in Excel. Will do in the future.

That power stress test is super useful information, a lot of speakers have minimum impedance in the 3-4 Ohm range, but enough phase angle to become problematic. Would love to see some AV receivers subjected to it.

The 3D graph doesn't seem intuitive though. Is there an option for 2D plots, with the different impedance loads being different coloured traces, phase on X axis, and voltage on Y axis?

I find the 3D diagram extremely useful and easy to read. What is the trouble with reading the diagram, and why do 2D?

A bit strangely, at 2 ohm it would not run with 0 load angle but did produce half the output at other angles (hard to see in the 3-D graph). Since minimum impedance is 2.5 oh, we can't fault it for this. FYI I tested a couple of amps at my disposal and the both got quite unhappy with varying phase angles, shutting down and such.

Perhaps this is the problem both of you referred to. It can be seen but it does take some effort to see the shading and shape of the curve. Perhaps do both the 3D and a 2D in cases like this?

A separate comment, I wouldn't mind if the diagram and test covered even wider phase angles, although many amplifiers probably would. I assume the power cube isn't set up for it, and would be feedback to the Powercube developer, rather than directed to this excellent site.

 

[Dirk_67]

I think I understand this Power-Cube diagram so far ...
but how long has this power to be delivered from the Amp ?
continuous / 20ms burst / some seconds?
and at what distortion-values (1% / 10% / clip) ?

 

[DSJR]

I like that idea in principle, but how do we decide what that simulated load should be? A worst case of available speakers, an average, or what?

No time to trawl reviews, but the average two way passive crossovers I've seen do appear on the face of it to have broadly similar characteristics (accepting that you may well find exceptions to this broad-brush statement). I'd suggest that three way models could be even worse, so I suppose for a product like this, a typical two way 'average impedance curve' could be useful.

 

[Steve Dallas]

I see a trend in this product brand. They consistently over-promise and under-deliver. Not to mention over-priced.

Sad

The key to buying Peachtree products is to watch eBay for blems. The blem is usually a flaw in the cabinet that you can't see in normal use. My two Nova 300s were $1400 each shipped, which I do not consider bad for the feature set, country of assembly, cosmetics, and amount of power available. (One of my 300s was reviewed on this site.)

As for the GAN version, the G must be for Gimmick, and I see no reason for it to exist with the 500 available using IcePower modules.

 

[goryu]

The key to buying Peachtree products is to watch eBay for blems. The blem is usually a flaw in the cabinet that you can't see in normal use.

As for the GAN version, the G must be for Gimmick, and I see no reason for it to exist with the 500 available using IcePower modules.

These Peachtree GaN amps seem to all have a blem and it's more than cosmetic- it's their lack of post filter feedback and the resultant load dependent frequency response.

 

[anmpr1]

I think I understand this Power-Cube diagram so far ...
but how long has this power to be delivered from the Amp ?
continuous / 20ms burst / some seconds?
and at what distortion-values (1% / 10% / clip) ?

The only time I encountered the device in print was in a review of amplifiers the Boston Audio Society conducted (written up in their Speaker publication). I'd have to do some digging to see the BAS protocol.

For his part, Aczel explained:

The Power Cube, a software driven automated instrument with a PC front end, measures the maximum voltage the amplifier can deliver to the load at 1% distortion for a duration of 20ms at 1kHz. The loads have impedance magnitudes of 8, 4, 2, 1 ohm, and phase angles of -60, -30, 0, +30 and +60. The graphic output of the instrument shows the 20 data points connected to form a more or less cubelike polyhedron, which illustrates at a glance the true dynamic performance of the amplifier.

The test only takes a few minutes per channel. Under ideal conditions the voltage sourced by the amplifier should be a constant. A real amplifier, even a very good one is going to exhibit some tilt in the cube... The extent of the tilt depends principally on the primary capacitor reservoir size, the losses across the output devices, and the action of the current limiter if it is present.

I have no idea if the device measurement protocol is configurable, but I guess Amir will discuss that shortly.

 

[anmpr1]

I tracked down the BAS tests, reported in their Speaker publication (Fall 2017). The material is of course copyrighted so I won't quote much. However for anyone interested, and for anyone with access to the publication, it is worthwhile.

A problem for manufacturers producing for the real world is cost to the consumer v intended application. Looking at a 'graph' printout has to be interpreted carefully, whether it's power, or distortion. In the BAS article, two designers (Bob Carver--then at Sunfire, and Tom Holman, audio engineering director at Apple, designer of the Apt electronics) discussed their opinions and reservations about consumers using something like the Power Cube for purchasing valuations.

Editor Alvin Foster wrote the following:

Not everyone is in agreement with AudioGraph CEO Lars Ohlen about the universality of all amplifiers outputting a perfect cube with the loads specified in the IHF-A-202 standard. Some well-known amplifier designers believe that test selection and performance required depend on how the amplifier will be used, especially where music is the ultimate signal. They believe that an amp need not pass all AudioGraph tests to be more than adequate for music playback. Passing all of the tests might be more appropriate for amps in certain industrial applications.

If ASR is going to provide AudioGraph measurements (which I hope will be the case), a discussion of its practical (to the consumer) use ought to follow. In any case, because it's an old design, I am attaching the Phase Linear 700 AudioGraph. Phase Linear was one of the first, to the consumer, high powered amplifiers. FYI

 

[pma]

This link is quite new and hope that it is accessible even without login:

How to test your new Audio Amplifier Design - PowerCube basics and example graphs

Lets see how our test systems can help you design your audio amplifiers. To understand the need of the PowerCube test, you must be aware of how a loudspeaker appears to the amplifier during dynamic conditions.

www.linkedin.com

- with graph examples and explanations.

 

[mhardy6647]

Pretty disappointing performance for that kind of... (ahem)... moolah.

 

[badspeakerdesigner]

You can see the load dependency already starting at 3k giving a slope or a rise in very wide band depending of speaker impedance this is potentially audible ? This is leads to unpredictable performance with your speakers and you should not have to do home auditions for amps ? And then you change speakers ? This also means that two people’s listening impressions of this amp even if done in a controlled ABX way can’t be compared unless they have the same speakers.

In my experience not only audible but easily measurable. I have some load dependent cheap class D amps and a few of them exhibited rising HF response with a particular pair of speakers I own. Lots of testing was done, even sending the speaker to the company to be analyzed. Turns out it was my amps. Only until I was able to get a hold of an amp that didn't have the load dependency was I figure it out. Since then I've been looking around trying to find an amplifier that won't do this but also won't break the bank.

A07 (class D in green)vs. Audiosource Amp100 (class A/B in orange), I had to do this quickly at a friends house and forgot my mic stand so I did my best to hold the mic in the same spot. Speakers are Parts-express Cnotes.

Here's another measurement that I took that shows how bad it can get.

I thought this was super interesting because it kinda took a big poop on my long held belief that amplifiers generally don't sound different. It looks like they absolutely can. I was also surprised that no one really seemed to think anything of this when I shared my info.

 

[pma]

I also have numerous threads and posts on this issue here at ASR, but in the huge number of other threads they have quickly faded away.

Comparison of power amplifier distortions and FR into complex speaker dummy load

Comparison of AIYIMA A07 with DIY class AB amplifier into complex speaker dummy load (and more amps added soon) This is a measurement comparison of AIYIMA A07 amplifier (powered by SMPS Mean Well RS-100-24 27V)...

www.audiosciencereview.com

Hypex UcD180HG HxR amplifier module analysis and review

Neat. Also note that one solder joint that hasn't flowed correctly. Some components are frighteningly close to the mounting screws. Tom I think that the resistor close to the heatsink screw might be an optical illusion because of the camera lens axis vs. PCB angle during taking the photo...

www.audiosciencereview.com

AIYIMA A07 TPA3255 Amplifier Measurements and Review - LM4562 (and OPA2134) option

Thank you very informative.

www.audiosciencereview.com

On Class D Amplifiers Measurements

Unfortunately they don´t specify small signal BW, but slew rate was an incredible 200V/µs. So here are the extremes in advance of power BW, which, after all has increased significantly over time...from my perspective class D still has to improve by a factor of 2-3, until they can really compete...

www.audiosciencereview.com

 

[Ajax]

Hi Amir,

Thanks for the review, which reinforces the need to measure everything that we possibly can. I appreciate few here need convincing of this.

Peachtree was as hot a brand as there ever was, revered on Audiophile sites for many years. Subjective reviewers lauded their amps and DACs, however, they have a history of under achieving SOTA by a significant margin. IMO the best way to describe the company is a well marketed brand that produces average performance with a premium price tag.

Here are another couple of examples:

Review and Measurements of Peachtree Nova Pre

This is a review and detailed measurements of the Peachtree Nova DAC and Preamplifier. It belongs to my son who bought it years back prior to upgrading to the Oppo HA-1. Peachtree site still show it as current but I don't think it is available in distribution now. It cost US $999 when it first...

www.audiosciencereview.com

Peachtree Nova 300 Review (Dac & Amplifier)

This is a review and detailed measurements of the Peachtree Nova 300 integrated amplifier with DAC and phono stage. It is on kind loan from a member and costs US $2,199. The Nova 300 fits in the same chassis Peachtree has successfully used for last 15 years: It is quite beefy and heavy...

www.audiosciencereview.com

Peachtree amp500 Amplifier Review

This is a review and detailed measurements of the Peachtree amp500 stereo amplifier. It is on kind loan from a member and costs US $1,499. The amp500 comes in the same packaging of many previous Peachtree products. I wish company would innovate here as the design looks kind of dated. Then again...

www.audiosciencereview.com

Compare these prices with say a Topping E50 or second hand Benchmark DAC 2 combined with a Hypex 502 amp. I appreciate many will feel comparing new with second hand is not fair, however, the build quality of Benchmark gear is exceptional. I've had three over a 12 year period that never missed a beat.

Amir, pls keep up the good work, your efforts really are essential and appreciated by those of us needing help to sort the wheat from the chaff.

 

[lewdish]

Looks like not all GaN amps are built the same, and much more difficult to design for over Purifi/Ice/HypeX modules