ZAPpulse 2.3SE vs. 700XE

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Several have inquired about the sonic differences of these two ZAPpulse variants. Especially since the 700XE under some conditions have up to 250 times lower THD than 2.3SE.

How does this play out in real life sound quality?

Listening tests have been performed with non-technical but musically qualified testers.

Switching back and fourth between the two amplifiers with remote controlled high quality relays, made it easier to compare.

The first test is done on a typical 3 way speaker 700 Euro each.
First with some typical modern pop music, or jazz music. The room and soundstage is very clear on both amplifiers, the bass is tight and dynamic on both amplifiers. In fact there is very little or no difference to be heard. Lastly going to a known "problem CD", featuring a male choir (something like turtle creek chorale) known to ditch almost any amplifier.
Class A, A/B or D. On this CD a slight difference between the two amplifiers is audible, a thin curtain on the 2.3SE is lifted away, and the sound cleared up on the 700 XE. But the difference is small enough, that you would have to use the A/B relays to notice the small sonic improvement of the XE. So i would say for listening to primarily pop music, and using a 'normal' level of speakers would not endorce the extra cost of the ultralow distortion 700XE amplifier.

Now second test switching to a set of Dynaudio Consquence, high end speakers, also price wise. These 1.5 meter high towers of pure solid rosewood cost around 9000 Euro each. It's a 5 way dynamic speaker, known as ultra revealing to details anywhere in the signal chain.
With the same CD's in test, now the improvement is more noticable, even on the pop and jazz CD's. The sound is simply a wee bit cleaner on the 700 XE. When going to the problem CD that can make hifi salesmen very tired, when you take it to expositions and shops, the male choir is now noticably cleaner and more distinct on the 700XE compared to 2.3SE. You have no problems seperating voices in the choir. When playing on the 2.3SE you could on these high end speakers hear the thin curtains clutter the vocals. The cluttering is completely abcent and the sound crystal clear on the 700XE. There is no difference in soundstage, and bass dynamics on these speakers. The linear bass down to 16 Hz is really impressive, and not at all lazy or damped. It simply sounded fantastic!

So i guess which version is the best depends on whether your speakers are extremely revealing towards the amplifier, or if your taste of music leans towards what i would designate as very complex vocal or instrumental pieces. If not the 2.3SE will give you just as much value as the 700XE. The tester's simplest conclusion was clear: give us the 700XE! :)

At this points only a few qualified listening tests have been performed, since only one amplifier actually exists with the 700XE's. But it is my hope that in time many users of this forum will contribute with their own experiences.
Now i know how i 'knew' Turtle Creek was a mixed choir. :xeye:
The track i always use of Turtle Creek is no 5 found on Reference Recordings RR-905CD (The one supplied with a HDCD license from Pacific Microsonics - RIP)

It's Rutter: Lux Aeterna but as it turns out on this very track Turtle Creek Choir actually sings with the Dallas Women's Chorus. That's what confused me to think it was a mixed choir. Sorry :clown:
Listening tests are continuing, primarily using the higher regions of loudspeaker. We are talking price range of 10-20.000 US$ per box now. I am not participating in these listening tests myself, the amplifiers are rotating to the homes of independent testers around the country, and i get reports from them as things progress.

The word is that the better the CD player and loudspeakers you use, the cleaner 700XE is compared to 2.3SE (and most other amplifiers). Some of the testers are using Class A and Tube amplifiers in the same price range as the loudspeakers, and so far, they have not found any specific point of complaint of the sound from 700XE. The room and perspective of the 700XE is reported to be absolutely exceptional compared to any Class D amplifier tested so far.

So at this point i can't wait to get the new amplifier out. ;)
Hi lars

It would have been wonderful to know which class D, classA, and tube amplifiers, the 700XE has been compared to so far, especially as you have indicated that the 700XE performance has been in the 10K-20K price region.

I would like to ask another question ... Will you be designing a SMPS for the 700XE?
Will you be designing a SMPS for the 700XE?

This is definitely an option i am considering.

However when you make a cost / benefit analysis of the SMPS vs a normal PSU, there is no clear weight towards the SMPS.

The good news is that SMPS is slightly lower cost, has a lower weight and it is more 'cool'.
But the bad news it produces more EMI noise, and for some types of SMPS the feedback loop of the SMPS can influence the sound especially in the bass region.

What good points can you come up with to favour the SMPS solution?
Hi Lars, you wote 'What good points can you come up with to favour the SMPS solution?' ... I am not going to say 'don't you know' ... ahhh I said it?

This is very interesting to consider or not consider? I believe that the current NUFORCE experience needs to be considered, but, I have to say that if you design a PS according to Dejan V. Veselinovic 'Designing your own power supply' ... ttp://, why the need for a SMPS solution, other than size and weight. A 1KVA tranformer supply with this PS design, does an amazing job.

Can a SMPS solution control noise and supply suffient voltage and current to u-pass a tradional transformer PS. Lars, you are the knowledgeable one wrsto this, what are your thoughts?.
KLe: My thoughts are, that i think a traditional PSU can do a great job, there are many theories about how you can take a PSU or SMPS to the next level, but at least some of these theories are C**P and only meant to support one guy's personal opinions. (I am not talking about any of those links you suggest, but just in general).

5 years ago, the trend said you had to use fast rectifiers, and 4 pole T-Network or Slitfoil capacitors, because this PSU favours microdetails and precision in the top. But today more and more people are going back to conventional rectifiers and caps, because the sound is more relaxed and liqiud. It all depends on what you prefer the most. We actually have stockpiles of T-Network and Slitfoil caps in stock, that no-one wants to buy. :bawling: Because when people actually hear a PSU with conventional caps and rectifiers, they prefer that sound instead.

So my road map is to test different approaches, and sort out the good stuff from the bad, and then design a SMPS / PS that kicks *** .. ;)
Hi lars

Yes Lars, what does that say and what do you say, 'But today more and more people are going back to conventional rectifiers and caps, because the sound is more relaxed and liqiud'

Wrsto Dclass amps the power supply must control ripple, especially wrsto an open loop design, class D amplifiers, and rectifier noise. Fast rectifiers, a good idea, but, noiseless rectifiers work, hence the PS that I have directed you too? PSR rejection is indeed an issue and the hints are at 'And on the electronics side … ', and I believe will complete the PS requirements. The PSU favours ease of dealing with noise and a low impedance supply is essential to delivering powerful dynamics, especially, wrsto, difficult speaker loads?

Lars, can a SMPS u-surp a transformer PS?
Hi Lars

Yes, 'stockpiles of T-Network and Slitfoil caps in stock, that no-one wants to buy', I have that problem with cable. Fickle industry isn't it, but that is what makes it exciting? What are your testers saying?

Of course, the traditional PSU can do a great job, but, if you could you give your opions on a SMPS, it would be cordially welcome?
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