TOPIC:

I am contemplating the relative differences between the PWRICE-125 and the PWRICE-250 before getting another set of amps for building a 2nd set of the LXmini speakers, and I had these questions. I have sort of come to some conclusions but wanted to sound out the forum and Devteam, hopefully.
1) Are the gain structures are identical for these two amps? I referred to the spec “nominal voltage gain” and this spec IS different for the two amps. So I suspect gain structure is dissimilar.
2) In my system, the input I will use for the amps is/will be AES/EBU. Does this make a difference re gain structure? For a given level of digital signal, does the voltage gain spec apply or does voltage gain only apply to an analogue input?
3) I understand from the previous thread that the differences in some specs are heatsink related. However I also that the specs for the ICE250 don’t appear to be as good as the 125. Specifically the 250 seems to have a higher noise floor and higher distortion and lower dynamic range, as follows:
a) “Output referenced idle noise” is higher on the 250 (35uv vs 20uv for 125)
b) “frequency response” exhibits greater deviation on the 250 by 0.10db (+/-0.25db vs +/-0.15db for 125)
c) Dynamic range is smaller, ie worse (112db for the 250 vs 117db for the125)
d) Transient intermodulation distortion is however lower, ie better (0.003% for 250 vs 0.007% for 125)
5) From those specs, should we conclude that up to the power rating of the 125 amp, that the 250 amp has inferior performance? The trade off being that it can push more peak/continuous power out, albeit with more noise and distortion

I don't think there's anything to be gained by going to the higher power amps in the LXmini application. (The 125 amps are easily capable.)
What is your thinking on this???

Dave.

When I play orchestral music eg Rachmaninov's 2nd, at loud volumes, the music does not swell as much as I recall on my previous system...

This can be due to compression with any number of explanations.
1. The amplifiers may be running out of headroom at the top end of their range
2. The drivers may not be so linear at the top end of their range
3. There could be some compression in the cables (I've heard this in other systems pre and post recabling)
4. Conventional systems may exaggerate this "swelling" effect, and the LXminis radiation pattern may mean that this will not occur the same way with the LXminis.

I don't know.

I am not at all experienced in interpreting speaker driver and amp specs, and I can't tell that the amps are "easily capable". I also do not have audio or electronic measurement tools other than a multimeter, I only have my ears to guide me and I am speculating as above. The comment that a similar model amp the next size up "adds more body and bass" is ubiquitous in audiophool commentary. That's basically where I am coming from. Also, excuse me for resorting to subjective impressions, but I do find that with some tracks, the low/mid bass to be somewhat thinner than I have heard.

I do plan to address factor (3) with some DIY cable. So on that front I will take care of that variable, I feel. But on points one and two, I was hoping for some comment.

I plan to build to your subwoofer design too Dave, as I have said in the OPLUG forum, and my gain question relates to that. If the structures are indeed differerent, then that adds more reason to just get the 125 amps again. I can either play with them in a 2nd set or use them in a SW build.

That's the thought process that led to the question, and I do acknowledge some information was available on the topic below, re thermal heatsinking affecting some specs.

FWIW, my take on "swell" is that it's the subwoofer and to some extent the upper bass/lower mid driver. A large driver for the latter always seems to do a better job... with that said, systems set up that way typically have competent subwoofers as well. I don't know what Dave's sub design is but my inclination would be to focus there.

Indeed John. If I did not have to worry about value for money I might easily just get the 250 and try that.

But all things considered, I think I will get another pair of the 125, and build Dave's subwoofer.

On a peripheral note, that PE cabinet for the subs is 29 lbs or so and I haven't asked PE how much it costs to ship that to Sydney. Prefab is what I need as I don't want to get into woodwork.

But thanks Dave and John. I think direction is set.

But I note DEV have not commented on the question of the specs per se, which remains of interest. DEVTEAM any chance of some feedback?

On the sub cab, if you register an account with PE then partway through the checkout process it will give you the shipping choices. If that's the 10" 1cu ft cabinet, it tells me $70.81 (which is cheaper than I would have thought!)

Postage to Australia for 2 drivers and 2 cabs is $US200. Parts cost is $300 before postage.

We're spending Christmas in the West Coast, and I am thinking of just bringing it back.

3 children and wife and I should have enough baggage allowance. But might incur her wrath!

Hmmmm maybe $200 postage might be worth it!

That sounds like some interesting logistics Which drivers does it use (just curious)?

In the OPLUG forum, in the LXmini public pages, there's a whole sticky thread on it, Dave has specified Peerless 830668 10" drivers @ $150 the pair from PE

cheers

Jay

@ Jay,

Really sorry about missing your thread somehow!! We've been a bit busy these days.. Thanks again for your patience..

With regards to the PWR-ICE125/250, there will always be a correlation between noise floor and power. If the amplifier has higher power, the noise floor becomes a bit higher. It is mainly caused by switching higher voltage on the output stage. Generally speaking, if the output power is higher, it is more difficult to get high performance as the trade-off's in many area are quite tough. For example, if we set dead-time shorter, THD becomes better while power consumption becomes higher. The hardest is to find the tradeoff I guess..

So, the performance except for output power tends to be better if you choose lower power. The priority in choosing the module depends on which performance customers put the first priority.

Does this clarify your question?

DevTeam

Exactly the answer i was hoping for thanks kindly.
Life is full of tradeoffs and thank you for explaining how the parameters behave with respect to each othet.
Jay