Well, I meant this quite literally. If you or Bert had heard the Orelos as they sounded in my room, I don't think you would have recognized them at all. And I think it would have required this first hand experience to really get a grasp of what might be going on.

This is in no way a criticism of you or Bert for not coming over. All your other Orelo/Orelino customers seem perfectly happy and you can't go flying around the world when something doesn't work out for one person.

Is this clearer?

Mani.

I'll take some measurements next week - pure 50Hz sine wave fed to speakers, recorded at seating position with measurement mic, and analyzed on Audacity. Should tell exactly what's happening.


Peter, what do you want me to say? I haven't expressed to anyone my real level of disappointment in the Orelos not working out for me. I know they're great speakers, but they way they sounded in my room...  It's a shame you never managed to make it over and take a listen for yourself. Actually, Paul's earlier account says most of it. The only thing it doesn't (can't) convey is my often deep exasperation over the last two and a half years of not enjoying music in my main room. My office  and portable systems have been my saviours in this time. I now have a system that I love the sound of in my main room. Quite frankly, I don't care if it's distortion all over the place - I'll take it in a heartbeat over the sound I had before.

Mani.

Yeah, I don't know how else you'd get a 109dB/W@1m efficiency from a single 12" driver if it wasn't horn-loaded.

Listening to sine tones at my seating position, I'm getting useful output to about 40Hz, after which it drops fairly quickly. Interestingly, I'm getting very good output at 50Hz with the Animas - there was almost zero output with the Orelos at 50Hz... in the same room and at the same seating position. Weird...

Mani.

Hey Anthony, the sensitivity of my speakers was measured at the output of the speakers, so I'm assuming it included the 1st order crossover components.

But I totally agree that running speakers actively is the best way. I've been there and done that (but not with horns), see attached. 4x Hypex HG700 amps per speaker, so plenty of power. And yes, the results were much better than with the passive crossover. But the gear takes over the room and I'm just not prepared to go there now. That's the beauty of the Orelo speakers -it's all packaged beautifully together.

Mani.

Peter, my understanding was/is that the Orelo wings are not there for horn-loading - they are simply way too small to achieve this at such frequencies. True horn-loaded bass units look more like below, no? The second pic gives an idea of the length required for true horn loading at low frequencies.

Mani.

This gives a whole new perspective to the 'loudness wars'. It's just as well that much rock/pop music only requires 6-10dB of headroom as the majority of 'systems' out there would start clipping with more. You're sitting at home with your 50W amp thinking all is good. Well, for a 10dB headroom you're going to need a 500W amp! With a typical pair of 87dB/W@1m sensitivity speakers you'd get 84dBSPL in a listening room like mine. With 'better' mastered music requiring a 20dB headroom, you'd get just 74dBSPL at the listening position before clipping.

Really interesting stuff...

Mani.

VJ, I found the 'Amplifier Required Power' calculator thanks. With a 20dB headroom, it looks like I'm good for 86dBSPL at my listening position with my 5W amps and 109dB/W@1m speakers. Good enough for me.

It's all very well talking about the need for high powered amps to cope with headroom, but I think there is another potentially very important consideration: the effect these high-powered (non-class A) amps have on the AC mains. My feeling is that they might 'modulate' the mains with their current drain as the music plays, which may affect the source components adversely. Pure speculation on my part, but it was part of my reasoning to go the high-efficiency fully horn-loaded route, without servo-assisted bass.

Mani.

VJ, a few really dumb questions (and a lot of dodgy maths, I'm sure - a few edits already!):

1. Why would I need such high ratings of continuous power for momentary peaks in the music? Edit: Ha, I should have read the article more carefully. "According to Crown's chief amplifier engineer, Gerald Stanley, amplifier continuous power and amplifier peak power are nearly the same. Typically, peak power is only 1 dB higher than continuous power, and depends on peak duration."

2. My new SET amp will be only 5W pc. So in order to achieve 20dB peaks, the continuous power will be only 0.05W. But, my new speakers are 109dB/W@1m (across the full range). With only 0.05W, I can still achieve an SPL of 96dB @1m (109dB-13dB) - is this correct?

3. Let's consider the Orelo speakers now. We've got something like 60W of power going into the bass unit. So, for the same 20dB peaks, we have only 0.6W of continuous power. I'm assuming that the 'true' sensitivity of the bass unit is around 100dB/W@1m (it's just 'servo-assisted' to match the mid/high unit). So what does the SPL work out to with only 0.6W? 96dB (or so) @1m? In any event, around the same SPL as my Animas with only 0.05W of continuous power going to the bass unit.

4. It seems to me that the sensitivity of the speaker (across the full range, not just the mid and high) is way more important than amplifier power, because 10,000W+ amps just aren't a realistic proposition for home audio use.  In which case, 99.9% of audiophiles are 'stuffed' as they use woefully insensitive speakers. Is this correct?

I'm sure you're busy, so if anyone else would like to chime in, I'd appreciate it.

Mani.

Ah, so it's not that the music is boring! Thanks.

Mani.

Oh là là... They certainly look great together. Is the Lambo as much fun to drive as the Alfa?

But surely neither is as much fun as sitting at home listening to your hifi? 

Mani.

Hey Paul, you never used a full horn system with SETs though, did you? High efficiency (>105dB/W@1m) is a must to get the best out of a SET, I think.


Well, be prepared to be underwhelmed. It doesn't sound particularly impressive to my ears, mainly because it doesn't bring any part of the sound to attention. I haven't thought, "amazing bass", or "amazing dynamics", or anything like that. But what I have noticed is that I sit through whole albums just listening (no playing on the laptop) and am surprised when the album finishes.

And I can't even suggest that it sounds 'real'...

Mani.

I think for the first time ever, I've got a system that actually helps me to relax. Personally, I now think single-ended amplification is necessary to achieve this. I'm sure most people here would disagree, and I could certainly be wrong. But let me just quote something that Nelson Pass has written about this:

Given the assumption that every process that we perform on the signal will be heard, the finest amplifiers must employ those processes which are most natural.

There is one element in the chain which we cannot alter or improve upon, and that is the air. Air defines sound, and serves as a natural benchmark.

Virtually all the amplifiers on the market are based on a push-pull symmetry model. The push-pull symmetry topology has no particular basis in nature.

Is it valid to use air's characteristic as a model for designing an amplifier? If you accept that all processing leaves its signature on the music, the answer is yes.

One of the most interesting characteristics of air is its single-ended nature. Sound traveling through air is the result of the gas equation:

PV1.4 = 1.26 X 104

where P is pressure and V is volume. The small nonlinearity which is the result of air's characteristic is not generally judged to be significant at normal sound levels, and is comparable to the distortion numbers of fine amplifiers. This distortion generally only becomes a concern in the throats of horns, where the intense pressure levels are many times those at the mouth, and where the harmonic component can reach several per cent.

We can push on air and raise the pressure an arbitrary amount, but we cannot pull on it. We can only let it relax and fill a space as it will, and the pressure will never go below "0". As we push on air, the increase in pressure is greater than the corresponding decrease when we allow air to expand. This means that for a given motion of a diaphragm acting on air, the positive pressure perturbations will be slightly greater than the negative. From this we see that air is phase sensitive.

As a result of its single-ended nature, the harmonic content of air is primarily 2nd order, and most of the distortion of a single tone is second harmonic. Air's distortion characteristic is monotonic, which is to say its distortion products decrease smoothly as the acoustic level decreases. This is an important element which has often been overlooked in audio design and is reflected in the poor quality of early solid state amplifiers and D/A and A/D converters. They are not monotonic: the distortion increases as the level decreases.

Mani.

I have been wondering for a long time (many years now) why I can listen to many 'lesser' systems (kitchen radio, car system, office system) for hours and yet when I listen to most 'hi-end' systems I'm actually quite glad when the music stops after only a few minutes because I can actually 'recover'. The hi-end systems are certainly 'better', in the sense that they sound more real. And I think this is where things go 'wrong' for the brain perhaps.

When listening to the radio in the kitchen, it's obvious that it's a reproduction. The brain is relaxed with this - no need to work to fill any inadequacies in - the radio does the job it was intended to do. But when listening to a hi-end system, there are elements which sound so real, but others that simply will never, no matter how good the system, ever sound real. And the brain then has to do a lot of work to fill these inadequacies in.

Mani.

Hi Arvind, that's really good to hear. Anyone looking for end-game speakers with decent bass should have the Orelos right up there on their list.


I don't think I ever came across this issue with mine - perhaps with certain XX settings. Have you tried playing around with SFS and Q settings to see if you can tame this? Otherwise, I'm sure Bert will come up with something.

Mani.

Thanks Paul, that puts a lot of things into perspective. Yes, I could have persevered with the Orelos, but I suspect it would have taken a suspended ceiling to really make progress, and I'm not about to ruin the great job the Victorian builders did 130 years ago (when British engineering led the way... how times have changed!).

My system will never sound like yours - yours assaults the senses (in the best possible way - the visceral impact really has to be heard to be believed), whereas mine massages them (but only when using a SET).

Mani.