Wht are modern speaker less efficient then the ones in the 60's 70's? - Page 1
Forum section: electronics / general

author: Beamin
author_rank: Super Contributor
timestamp: August 23, 2018, 04:24:23 am
content: Many of those old Hifi systems had speaker with 100db at 1 watt 1 m. Many stereo amps were also rated at 25 watts where as today you would see 100 today. I see why they had to be so efficient, the amps and technology couldn't do 100 watts or at least not for the price.So as amps got more powerful why did they start making speakers less efficient? With more power it seems like you would get more bass and mid bass with todays speakers having big heavy magnets and matching voice coils. Was this the compromise to becoming less effective? Seems like the speaker companies would have to know the amp companies were doing this.How did they get bass out of 12" cones with those little tiny magnets or did they not?Heres a related stereo technique:My knowledge is limited to car stereos but I always wanted the loudness of a 15" with the accuracy and punchiness of a 10" sub. I figured out how to do this: Get a high end 15" sub that can handle a lot of watts 500 in my case. The speakers needed a 1 cu ft of air behind them and the speaker holds .5 cu feet in front or took up .5cu feet in back : So I took a .5cu foot box and mounted the speaker upside don so you saw the back of the speaker. I wired it so that the speaker fired into the box. For flattest frequency response you want a sealed box as ported have a peak frequency and bandpass have even greater peak. I then got a high end D class amp that did a lot of current that was higher in wattage then the speaker around 800 watts. The result was a super loud but more importantly really clean bass from 20-110hz. You can go to 110 because of the small box size and also still have the loudness at 20 because the amp is so big. It also looked cool and when listening at normal volume had tight sharp response. most subs won't do the really low frequency unless it turned up loud. This probably wasn't possible with those high efficiency speakers. Two 1 Farrad caps along with a 160+ amp alternator were needed for this to work.

author: BrianHG
author_rank: Super Contributor
timestamp: August 23, 2018, 04:50:00 am
content: QuoteThey got some bass, but not very low frequencies like the current car stereos which shake the windows of all the houses on the block.As for my home setup, I'm not sure, but I get plenty of bass and subsonic out of a 8 inch woofer, and at half the power, however, in my speaker's design, it is the huge tower cabinet with a huge internal specially shaped funnel with chambers inside designed as an inverted VLF 30hz whistle coming out the bottom of the cabinet. The timing from the inside rear of the woofer is phase delayed so that vent at the front bottom of the speaker outputs an in phase response with the front of the woofer at 25-45 Hz. Because of the whistle design, that speaker generates more than double the output at these very low frequencies for the same amount supplied wattage. They were designed to give you a subsonic kick with vacuum tube amps starting at 50 watts yet they can handle 200 watts continuous without issue other than annoy the neighbors. At 200 watts RMS, many action movie sequences hits you at your core and knocks you back into your seat. And since they are full range 25Hz to 25Khz, no stupid separate out of phase mono subwoofer needed.Though, it must be said that my speakers are 20 years old, authentically made in the US, and are around 5k$ in today's dollars. You wont find any Chinese built junk today which will come close & expect to pay around 15K$ for a modern speaker to come anywhere close.

author: james_s
author_rank: Super Contributor
timestamp: August 23, 2018, 04:53:40 am
content: As far as I've seen, the less efficient speakers came along side by side with the amplifier power arms race of the 70s-80s. As amplifiers got more powerful, speakers were made which could handle more power, and speakers got smaller. It wasn't something that just happened overnight.

author: Keicar
author_rank: Regular Contributor
timestamp: August 23, 2018, 05:32:26 am
content: I suspect the popularity of smaller enclosures is part of the story - my understanding is that it's a case of "small box, good bass, high efficiency - pick two" (or maybe one!).Cheers,Karl.

author: dmills
author_rank: Super Contributor
timestamp: August 23, 2018, 09:56:03 am
content: Pretty much.Basically speakers are an optimisation problem, and as power got cheaper and easier the optimum design moved towards smaller less efficient drivers.One other thing that smaller drivers really helped with is that an 8 inch cone can be crossed over higher without cone breakup becoming an issue, so it is easier to get the crossover point above the vocal band, this generally makes (all other things being equal) for a better sounding box.You can also take advantage of all that amplifier power by doing significant EQ ahead of the amplifiers.Now when you have a situation where making LOTS of noise matters (say a PA system), the advances in materials (Magnets and cones) and better system modelling mean that 105dB/w @ 1m is very routine, but that is just a different set of optimums, nobody uses tapped horns and the like in domestic systems.Regards, Dan.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 23, 2018, 12:20:53 pm
content: Isn't the demand for more efficient speakers increasing as battery operated Bluetooth speakers are getting really popular?

author: Cyberdragon
author_rank: Super Contributor
timestamp: August 23, 2018, 12:51:11 pm
content: Quote from: NiHaoMike on August 23, 2018, 12:20:53 pmMost of those are absolute trash consumer chinesium though. Using drivers basically sized for earphone use and overdriving the hell out of them just so you can hear anything.

author: Circlotron
author_rank: Super Contributor
timestamp: August 23, 2018, 01:06:21 pm
content: A speaker with a large Xmax will often have only part of the voice coil in the magnet airgap and a whole lot hanging out front and back. When the voice coil moves back and forth a constant amount of voice coil is always in the gap. Good for linearity, bad for efficiency. Old timey high efficiency speakers had all of the voice coil in the gap.

author: b_force
author_rank: Super Contributor
timestamp: August 23, 2018, 01:13:00 pm
content: Quote from: Beamin on August 23, 2018, 04:24:23 amInstead of chit chatting about subjective matter, lets get back to the original question.That really depends what kind of speaker you're looking for.With PA speakers (sound-reinforcement) you can still find drivers with high efficiency.90-100dB /W is not uncommon.The biggest difference is basically optimisation in "the motor" (the magnet system).The response of a loudspeaker is a big pile of compromises that need to be made.In the old days amplifier power was VERY limited and very inefficient (maybe couple of hundred of Watts at most with a PPP KT88 with basically no efficiency, lol)To compromise for that speakers were designed to fit in a bigger volume.Since you can compromise electrical power with acoustic volume.Also, you need to take the word "designed" with a grain of salt.Knowledge back than wasn't as good as today, mostly because FEM analyses and optimisations.There is actually also another side of this story.When developing a loudspeaker you roughly have a compromise between efficiency, lowest frequency (Fs, resonant frequency), total bandwith (so what will your highest frequency will be), distortion, maxSPL levels and needed acoustic volume.Since power isn't such an issue anymore, most manufactures give up efficiency to get a lower Fs plus the speakers can be used within a lower volume.(people don't want enormous speakers anymore).The magnet does play part in this, but it is definitely not always telling you the whole story.Also the material of the magnet really matter, ferrite, neodymium and in the old days they used alnico.But that gives yet another compromise in terms of thermal heat capacity and such (you can never win)In some cases people want maximum portability, so this means a lot of (extreme) compromises need to be made.Bluetooth speakers are an example of this (sorry, but I don't see how people can bring a 18" horn to the beach?)So in the end it's all about what people really want and need in a certain environment.Unfortunately the marketing department had a good go with that and that's why there is so much misconception and myths around audio.

author: PointyOintment
author_rank: Frequent Contributor
timestamp: August 23, 2018, 01:49:46 pm
content: Quote from: BrianHG on August 23, 2018, 04:50:00 amThat sounds like the kind of thing that would be worth a proper writeup, with diagrams and stuff.

author: tom66
author_rank: Super Contributor
timestamp: August 23, 2018, 02:01:44 pm
content: Quote from: Cyberdragon on August 23, 2018, 12:51:11 pmNot really. Tore down some Bluetooth speakers recently for competitor analysis. Mostly well built, the £40 Anker Soundcore 2 was very nicely built and the drivers are well over-specified in that. It also didn't clip once on any input, even at max volume, and objectively sounds quite decent.

author: b_force
author_rank: Super Contributor
timestamp: August 23, 2018, 02:10:51 pm
content: Quote from: tom66 on August 23, 2018, 02:01:44 pmMost well known brands have respected brand drivers in them, that is correct.Like I said before, there is only so much you can do from a 1-2" driver.Actually I am sometimes still amazed what they can with it all considering.Most of them use DSP to prevent clipping etc (although a lot of times this is even integrated in the Class-D chip)

author: vk6zgo
author_rank: Super Contributor
timestamp: August 23, 2018, 04:55:01 pm
content: Back in the day, the only people with"Hi-FI"systems were geeks.They were the sort of people who didn't care if their speaker system took up half their lounge room.These speaker systems were large, &weremore efficient than modern types.When "stereos" became mainstream, people wanted nice, small, unobtrusive speakers.Such speakers, were by definition inefficient, but serendipitously, the availability of higher power output solid state amplifiers coincided with their introduction, so they became the norm.Any loudspeaker is horribly inefficient, so we are really only talking here about relative degrees of inefficiency!

author: BrianHG
author_rank: Super Contributor
timestamp: August 23, 2018, 05:35:51 pm
content: Quote from: PointyOintment on August 23, 2018, 01:49:46 pmAsk and you shall receive:https://youtu.be/wY0ZxMJ6FCE?t=965(8 year old model)Latest 2018 version of this speaker technology, with ribbon tweeter: David Tower, located at the bottom of the page:https://www.solusloudpeakers.com/h-pas-productsIf you watch as far as his graphs in the Youtube video, you'll see a speaker so flat from 30 Hz and up which will roast top notch headphones & with the new ribbon tweeters, like my 25 year old versions of the speakers, they roast any headphones with a good enough amp. You can email a request to SolusLoudspeakers for the latest speaker's dimensions and frequency response plots for the David Tower if you like.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 23, 2018, 05:44:46 pm
content: And yet, overall, a set of modern speakers driven off a modern digital amplifier is way more efficient than a set of old speakers driven off an all tube amp. Which one sounds "better" depends on the listener, with the younger ones tending to prefer digital while older ones often prefer tube.It is also worth noting that the recommended maximum volume of 85dB for extended listening happens to be very close to the dBA/dBW rating of many modern speakers, meaning that in typical home use, the average power applied to the speakers is less than 1W.

author: Richard Crowley
author_rank: Super Contributor
timestamp: August 23, 2018, 05:46:26 pm
content: They had to be more clever back then to get decent sound levels AND decent low-frequency response. It involved a lot of experimentation and "tuning" enclosures and matching drivers to get better LF response. Typically by using low-Q resonance to bring up the bottom end.But now, when power is dirt-cheap, they can use "brute force" and active methods. And some companies like Bose use a combination of clever resonance-enhanced LF and brute-force active EQ to make pleasant-sound consumer products. Although reviled in pro audio circles: "No highs? No lows? Must be Bose"I recently got a pair of "IK Multimedia iLoud Micro Monitors ultra-compact 3" studio monitors" People on audio discussion groups had been raving about them for a year and I needed something compact for mobile video and audio production setups. They are remarkably heavy for their very compact size and they pump out an amazing amount of LF for 3-inch drivers. Certainly not the kind of thing anyone could even imagine back 50 years ago.

author: b_force
author_rank: Super Contributor
timestamp: August 23, 2018, 05:58:02 pm
content: Quote from: NiHaoMike on August 23, 2018, 05:44:46 pmThat word, the horror

author: floobydust
author_rank: Super Contributor
timestamp: August 23, 2018, 06:40:56 pm
content: Modern LF drivers have stronger (magnetic) motors- better magnets and smaller air-gaps.I haveJBL 2235's93dB 1W/1m with a 8.5kg old school magnet and 8.5mm Xmax.Faital Proneodymium magnet is 99dB 1W/1m and 5.8mm Xmax. at much less than half the weight of the JBL.6dB is a huge difference. But the newer magnets have a shorter B-field, so less real output.Edit: Checked B/I factor JBL is 20.5 N/A and the Faital Pro is 16.7 N/A so I must be out to lunch.

author: Beamin
author_rank: Super Contributor
timestamp: August 23, 2018, 06:46:35 pm
content: To my ears I never liked ported speakers. Real audiophoolery comes from sealed enclosures. They sound completely flat and if you want more bass you can use your eq instead of trying to figure out what frequency the speaker resonates at.As a kid I used to build bandpass boxes because they looked cool if you used crazy thick plex glass and were insanely loud. I once built a box for dual 12" that had a cu foot in front and another behind the speakers with a long port tube for a port. They could make the change jump out of the ashtray. The car I had them in also rattled the interior apart. You would increase or shorten the size and length of the port to make it peak at a certain frequency. Was a real art to make them. Also I found that using anything less then high density particle board would lessen the sound and make the bass less crisp. My first one had a thin plexyglass window that popped out because it distorted so much. Sound quality? What sound quality?

author: b_force
author_rank: Super Contributor
timestamp: August 23, 2018, 08:19:26 pm
content: With all the respect, but real audiopholery comes from judging one solution from others on an absolute way.They all have their pros and cons. Depending on the situation one can never say something by definition will always be better than the other.In fact if you get the frequency response equal they are technically the same.Guess some people lost their basic control theory a little bit after all these years.

author: VK3DRB
author_rank: Super Contributor
timestamp: August 24, 2018, 11:28:06 am
content: I restore Australian 1930's console radios. The speakers were generally VERY efficient because there was often only a couple of watts available to drive them from their valve AF amps. These days, we have it easy.A parallel is the smartest programmers in the 1970's were people like Dan and Kathy Spracklen who wrote Sargon chess to run in 4K of RAM. These days, few people care about efficient code. Compare to Apple's iTunes - bloatware and crapware rolled into one big mess.

author: james_s
author_rank: Super Contributor
timestamp: August 24, 2018, 03:28:03 pm
content: At one point iTunes was actually quite good and I used it as my primary music management software even on my Windows machines. They kept screwing with it though and completely ruined it then just made it worse.Anyway as far as that gear sounds best, sound quality is a very subjective matter. Some will prefer the cleanest purest sound they can achieve, while to someone else equipment that from an engineering standpoint adds all kinds of distortion could sound better to them. Recorded music is never going to sound the same as a live performance anyway, most of our livingrooms are not remotely like a concert hall from an acoustic standpoint.

author: raptor1956
author_rank: Frequent Contributor
timestamp: August 25, 2018, 05:15:38 am
content: Digital amps get a lot of negative press, but modern ones are not bad at all, particularly for bass drivers. As switching speed increases the frequency that can be reproduced with great quality also increases. In power limited uses digital is the way to go as its pretty much the most energy efficient way to produce sound amplification.I would agree that older listeners tend to prefer, or think they prefer, tube or non-digital amps while younger listeners are more open to digital. Sadly, the ripping of CD's into low quality MP3's with low bit-rates have conditioned the last generation or two and they now can't tell the difference.I personally have a digital amp based AVR and am quite happy with it though I would like a lot more power at times. What I can't tolerate is low bit-rate digital music that sound like your listening to it under water -- how can anyone listen to that crap.The next wave in audio/video sound reproduction in my view will be to build speakers with amps built into them so they are perfectly matched to the drivers. A speaker may have a 3-way design with, say, 5 drivers (1 bass, 2 mids and 2 highs) with 3 separate amps with a common or separate, beafy, PS. The receiver will send the audio in digital format via wifi or LAN along with EQ, timing, compression/expansion and SPL commands. Each speaker will then process the commands and with the timing info sync the audio as required. There will be no analog crossover as it will all be done digitally. I'd argue for 24-bit 96kHz as the standard.Brian

author: dekra54
author_rank: Unknown
timestamp: August 25, 2018, 06:26:01 am
content: As many already said: Amplifier power costs next to nothing these days. You can get an integrated ~500W 8Ohm amplifier IC for around 5$ in single quantity. Add a handfull of caps and resistors + powersupply and you have a very powerful amplifier. Compared to "the old days" where you needed about 10 power BJT's per side + all the other compnents to get it working.And it is easier. Just throw 500W at a 97db efficient Speaker with enclosure eg. your standard reflex cab than using a 250W hornloaded system which can be as efficient as ~ 105-108db but you have to develop it individually for each chassi and is a nightmare to build compared to a Box with a hole/tube.