What's the catch - horns and compression drivers 1/II.
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- เผยแพร่เมื่อ 11 ต.ค. 2024
- -What does a compression driver do WITHOUT A HORN?
-How does the horn modify its response?
Do you know what the best dome tweeter can do?
Do you know what compression drivers can do?
Food for thought about tweeter technology. That was the previous episode...
now we delve into the mystery of compression drivers and horns!
This is part of the A5 VOTT series, looking at the compression driver used in the A5.
Currently there is little to no information on how to build cabinets for 515 and 288 series drivers. I'm stirring up the scene, and throwing this stone in the pond to rediscover these magnificent drivers, which are supposedly the finest high efficiency woofer and the finest compression driver ever made.
I've built my speakers with 515C and 288H. I call them Voice of Lancelot (VOL). They do not follow any currently available cabinet concepts or designs, they are the result of my two decades long research and know-how passed on to me by one of the greatest minds of high end audio (Stu Ono), who broke down ever single speaker design and taught me how to improve on them. Sadly, he is gone, but his legacy shall continue.
VOL includes a few groundbreaking concepts, the synthesis of the current cabinet design principles, backed by music instrument making principles, adapted for human auditory systems requirements and the actual room requirements (as opposed to designing for an-echoic chambers and optimizing for measurements rather than human hearing). This video series will start introducing these ideas to help you get ideas to build your own design, and enrich your life with truly astounding musical instruments. As the saying goes, once you go Altec, you can't go back.... the adage is true, a properly built Altec is what I (and many) think as the finest music reproduction instrument available in our age. Even better, you can use other drivers, you will be able to apply what you learn, and leap to the next level!
Kaplah.
MUSIC: Wolgemut Schauspeluden. CD.
I'm glad you mentioned how we've sacrificed fidelity and realism for size and convenience. I absoloutely love compression drivers and gotta say, if anyone out there hasn't experienced HLCDs, you don't know what you're missing.
* there is no free lunch, there's always pros and cons of everything and HLCDs aren't perfect either. If I had to say why I like 'em, these are my reasons:
1.) CDs never sound strained when pushed to loud sound levels
2.) clarity
3.) efficiency (most will reach ear-bleeding loudness with fairly low input power) In a car, the average 75 watts per channel amplifier will do the trick
4.) replacement coil/diaphragms are available, so if you smoke one, it can be fixed
Now, for the cons:
1.) large physical size makes them difficult to fit in mobile applications
I've been loving your channel! Will you please do a video on the strength /weakness of planar magnetic speakers like the BG Neo 10/8/3?
Thank you Dru for your suggestion! I will do a video on these drivers :) I'm glad you like channel! cheers, Janos
Any recommendations on low crossing compression drivers you have heard apart from the Altec 288? For the moment I've found these candidates: Altec 290,291, the more expensive TD2001 then cheaper: EV DH1A (I have these), or JBL 2447, in current production: SB CD65/75, Faital pro HF206, Radian PB950, Celestion Axi2050, TD4001
I have not played around with them, so cannot recommend how low they would get. The feedback I heard on Faital and Radian is that they don't want to be pushed low, they are really voiced for the 1kHz+ range.
@@realworldaudio Yes saw those comments too but then I hoped it may be fine for way below specced power levels, so hence I asked. But generally yes, about all the modern available CDs seem to suffer that limitation...
That's so true. I never realised how good speaker can sound until i listened to a pair of JBL Project K2. And i have been enjoying this setup since the 90's. I initially augmented with the beryllium UT045be, but now switched using ribbon design beryllium from Pioneer PT-R9 that pushes the frequency response from 50khz to 120kHz. Sounds so much better now when paired with the K2. My friend too, i took a mini JBL 4306 for him to have a listen, after this experience he was totally convinced about the compression driver potentials. We build his system around JBL LSR705i and LSR708i... sounds fantastic! Now he is running JBL M2, together with beryllium ribbon Pioneer PR-R7iii. And me too building a new system based on M2 components...also augmented with beryllium ribbons, never looked back ever since. These components sounds superb especially running a digital active crossover setup. 😊👍
Cheers, superb! & thank you for the tip on using the Pioneer to supplement the ultrasonic region.
@@realworldaudio We would like to share with you ALL a few other very useful tips, which we have learnt and discovered during our past decades of audio journey that would surely greatly help in achieving great sound without breaking the bank.
TIP #1: Forget Passive Crossover and go Active Crossover
TIP #2: Look for hidden gems in speaker design that are based on the most advanced compression driver and waveguide design
TIP #3: Use a Digital Active Crossover that supports 24-bit 96kHz and run a steep crossover slope of at least -48dB/Oct
TIP #4: For HF Amp, choose a model that would provide super wide bandwidth and linear response into the 1MHz range.
TIP #5: For LF Amp, choose a model that would provide high efficiency drive to cater for low impedance high current demands of the woofer unit
TIP #6: Forget PreAmp and choose a musical DAC that has HQ solution towards volume control
TIP #7: Focu,s on reducing jitter and achieving high-accuracy clock in your digital source
TIP #8: Connect your digital source to Digital Crossover and to the (multi) DACs and their respective amps, to drive the speaker drivers directly.
TIP #9: Apply jitter reduction components to fine tune your system
TIP #10: Component placement. Group DAC and Amp as close to the speaker they are responsible for driving as close a possible and run as short analogue cable as possible.
On Tip #1, without going into too much technical details, passive crossover introduces a lot of issues into the audio playback pathway that degrades the signal and is hard to correct. Also it is difficult to achieve steep crossover slopes with passive approach. For details, have a read on this white paper: www.deqx.com/wp-content/uploads/pdf/What-is-DEQX-Technology-Whitepaper.pdf
On Tip #2, as much as I am a nostalgic person who admires great classical compression driver design, the reality is, there has been great leaps of advancement being made by JBL in recent years. Many would have heard the amazing sound from the JBL M2 monitors. But much less well known and unheard of (and auditioned) are the JBL 7-series monitors. There are 2 passive models in this range the 705i and 708i. Both are jaw-droppingly good and way more afforable than the M2 (not that M2 is too expensive, it is reasonably priced). Very few people would have had the opportunity to audition these speakers beacuse they are mainly sold to Broadcast stations and recording companies. And unless one works in such environment, the chances of working and listening to them are rare. There are no Audio Shop we know of that stocks these speakers for demo. And because they sound so good, very few pickings in the 2nd-hand used market...unless a recording studio goes out of business due to financial reasons. You all just have to take our word for it, the sound from these monitors defies normal reasoning and are jaw-droppingly stunning. The sound is completely disproportional to their physical size. Even the smallest 5" bass on the 705i is unbelievable. It may look ridiculously tiny, but certainly not its sound... and the bass is amazingly deep, clean and good. Check out the DDD driver and its very long extended bass port if one gets a chance to see the real thing. And they are very afforable for what they are capable of delivering. We would recommend to start with the 705i for the best bang for bucks. And if budget permits look into 708i. The compression driver and waveguide on these monitors would deliver the most beautiful and extended highs most people would get to experience, from a monitor speaker that is very close in performance to their elder brother the M2 monitor. It would definitely put a huge simile on any audiophile, listening to these monitors for the first time (and each and every time subsequently) on a good proper digital active crossover setup. It would give new definition to all the familar tracks one is familar with, revealing new details on each listening session. These 7-series monitors would be our prime choice recommended to start with a digital active crossover setup. Later if budget permits, seriously look into upgrading to M2 monitors. Or for the more technically inclinded a DIY version of the M2.
On Tip #3, The DEQX unit may be a bit too pricy for someone who just started with Active Digital Crossover and wants to evaluate how much improvement an Active Digital Crossover can provide. We highly recommend to look into NanoDigi 2x8 B as an alternative. We have achieved superb results in Ken's setup deploying NanoDigi. It will definitely provide the eye-opening revealation needed to convince anyone the benefits of a good Active Digital Crossover setup at a super affordable price. We run a -48dB/Oct crossover slope on Ken's setup. For more advanced setup and when budget permits, look into upgrading to DEQX. With DEQX, which I personally use, I run a -300dB/Oct crossover slope.
On Tip #4, This tip alone is probably the critial success factor that reveals the true potentials of a good digital active crossover setup is capable of. Without an amp that is highly accurate in time domain response, the benefits of the active digital may not be that apparent. Forget about Tube amps they have restrictions on the high frequency bandwidth required. We need an amp that has a 3MHz super wide bandwidth and has a flat response within the the first 1MHz bandwidth. There are few amps that will meet this criteria except the Goldmund JOB4 circuit. Of course there are various amp models within Goldmund with JOB4, but there are also variants of JOB4, if you know where to look. Goldmund's professional branch StellaVox makes a PW1 mono block. Not only that it features JOB4, it supports XLR balanced input. These amps are super difficult to find in the market but if you are one of the lucky ones to find one, you are blessed. The PW1 would be our top pick, even over the Goldmund amps because of the XLR Balanced input support. Then there is the JOB amps and even if you know where to find a NuForce STA200 which also features the JOB4, in a slightly scaled/powered down version. The claritiy of the JOB4 has to be experienced to be believed. In our opion this is the most transparent amp in the market, regardless of price. It has the potential (if you deploy it right) to make your audio equipment dissapear and start to enjoy the music itself. It is also super revealing and will allow debugging what problem one setup has easily. There is no masking of problems with this amp.
Check out this Goldmund Amp review to get some insight into this advantage:
www.monoandstereo.com/2016/05/the-goldmund-telos-360-universal-mono.html
On Tip #5, we found to get the most out of the latest generation of JBL DDD bass drivers, it needs power. To get optimal and extended bass response, you need amps with high current capabilites, with power delivered in an efficient manner. The best balance we found are the 500w version of ICEPOWER amps. The ICEPOWER amp can deliver incredible amount of current to achieve full control of the bass drivers. With an active crossover setup, we can bypass all the energy sapping inductor coils in a crossover network. So always wire the bass driver directly to the ICEPOWER amp. We use one 500w ICEPOWER monoblock amp per bass driver. The best value for money implementation of ICEPOWER 500W we found is from a less well known source - Ghent Audio GA-M500P. They are excellent value for money and are highly reliable. And have been providing excellent performance in our setup since we went down the path of full active digital crossover setup over a decade ago. On a proper setup, these amps will allow the awesome JBL DDD driver to completely control the air mass within the listenig room.
On Tip #6, despite being nostalgic, we have assessed many latest modern DACs and reckon that the Wadia DAC still sounds the most musical and is still our favourite choice. Wadia's implementation of the digital volume control is also superb and maintains very good resolution within the typiacl listening range. The sweetspot is around the 85 setting and this is the norminal setting we aim to tune our setup towards. Of course, with multi-channel for 2-way crossover, one will need 2 DAC units. In Ken's setup, we deploy dual Wadia 122 DACs. These DAC despite being very affordable sounds incredible! We paired NanoDigi in 2-way setup with Dual Wadia 122 powering his HF and LF amps driving a pair of JBL LSR708i. And the sound is truly heavenly. Definitely an eye-opening experience and we can confidently say sounding much better than many system that cost 10x-20x more! The clarity and high resolution power of his setup has to be experienced to be believed. And bass from that 8" DDD driver is stunning to say the least....completely defying what 8" drivers are capable of delivering. It is hard to put this listening experience in word, one just have to experience this at least once in their life to believe this.
FYI, in my setup I deploy dual Wadia 322 DACs with DEQX as active digital crossover, with a Goldmund SR8 to support and decode mult-channel and digital source selector and digital volume control.
On Tip #7, try to use a digital source with as precision in clock signal as possible.
Starting from the digital source, we looked at how the digital clock can be improved.
I run 2 main digital source. To cater for various digital audio media on files, I deploy a modified Wadia 171 with high precision DEXA Neutron-star clock mods and various upgrades.
For traditional CD/SACD I deploy a ESOTERIC X01 Limited player.
With a highly accurate clock, when we deploy the digital reclockers in tips below, you have a much beter chance of achieving HQ audio.
On Tip#8 and Tip#10, the focus is to significantly reduce channel crosstalk and noise pickup during signal transmission. With a 2-way setup a standard appraoch is to have one DAC decoding HF for Left+Right and another DAC decoding LF for Left-Right. But this is not the optimal setup. A better setup is to have one DAC decoding both the HF and LF of the LEFT channel; then second DAC decoding both the HF and LF of the RIGHT channel. And more importantly, reposition the DAC to very close to where the speakers are, and power the monoblocks within close range.
NanoDigi supports this remaping of digital channel output to achieve the topology of this setup. This way all the analogue signal cable runs are kept to minimal and no issue with channel crosstalk, as the LF and HF signals are correlated in the first place. The longer run of digital from NanoDigi to the DAC we would recommend running Glass Optics. This can be achieved easily as the Remedy Reclocker supports both Optical and Coaxial digital IO. Always run Balanced XLR whenever possible.
With speaker cables from amp to driver, try to bypass the original passive crossover network whenever possible. Modify the wiring within the speaker if necessary to achieve direct coupling. Avoid interaction of the signal with any capacitors and inductors to preserve signal integrity.
Choose speaker and signal cables with very low dielectric constant (eg. Air + Teflon/PTFE), to minimize any potential smearing of original signal.
On Tip#9, this is the element that will bring a lot of fun and joy to this type of digital active crossover setup. Through much experimentation, we have found that by incrementally improving the time domain accuracy of the playback signal, the audio quality is very notacably improved. Although both digital source here have highly accurate clock, the signal transmission and preservation is the challenge here. It is amazing by progressively introducing a digital reclocker (Remedy Reclocker from Wyred 4 Sound) on each of the digital signal paths, we hear quite notacable improvements. In all, I have now 7 reclockers running in my setup. This agian, would require one to experiment and experiencing this improvement for themselves to believe. It sounds unbelievable...but as one recloker is online, two is online...it gets better and better...even down to the 7th unit. Try removing one reclocker at a time and see if one can tell the differrence! It's very fun! And these remedy reclockers are very affordable. So definitely very high on our list for the afforable tuning list worth trying.
@@damianhla Thank you for sharing, and for all the details, and the encouragement for active crossover.
@@damianhla Thank you for all the effort you put in to share your findings! I will not let it stay a sleeper, will make a video and present your solutions and recommendations, with your permission. I think you have put in a LOT of work and love, and it payed a lot of rewards.
One reason I have shied away from electrostats and magneplanars is because their diaphragm seems so constrained, not allowed to move. I would think this would hinder dynamics. Yet, when you look at a compression driver, there is not a flexible surround typically on compression driver diaphragms. Could the horn be making the work easy enough that it doesn't need the excursion?
Most of the efficiency conversion is done by the compression chamber, the horn is just a gearbox to shift the gains in efficiency from the higher to the lower frequencies. Sound generation has two components: 1 excursion 2 efficiency of energy transfer from diafragm to air. The energy transfer is an incredibly wasteful process, that's why we need super high excursions with normal drivers. Also compression drivers are not asked to work below 500Hz (or usually even higher), and these the sound waves require very small excursions compared to bass. (The excursion is the low frequency response limiter for compression drivers: eg an Altec 288 can easily go down to 100Hz, but at low SPL because that frequency demands very high excursion, that it does not have.. )
@@realworldaudio thank you so much for your reply! I suppose the next questions might be: what would a compression driver be like with a surround, what about horn-loaded woofers, and is the reason for high power handling because the diaphragms are so durable without the surround.
What is it about dynamic drivers that compresses compared to horns?
@@ColocasiaCorm The relative compression is caused by the lack of headroom. Compression drivers have +20dB or more headroom over an average dynamic driver. So, basically when a dynamic driver is pushed to the limit, a compression driver is working at around 0.1-1% of its potential. The more a driver is pushed, the more it distorts.
Hello boss, what would be a good midrange driver for a realistic 4024a
Here's a thread on it: audiokarma.org/forums/index.php?threads/mach-one-4024-4024a-4029-information-and-upgrades.261425/
I'd say though that first go for upgrading the crossover, will benefit greatly from higher quality caps and resistors & keep the original midrange
@@realworldaudio one of the midrange driver is not working. Thank you sr great help !
@@elchachote33 What a bummer! I hope you can find a replacement.
I’ve never heard that your skull is a “receiver” to 100Khz frequency, at my age I’d be shocked if I can hear 10k. Bell Labs did a sex/age study on hearing acuity, and I was amazed how dramatically our hearing, at least using our ears, falls off. I’ll have to hook up a super duper high frequency driver to see if my skull and brian can detect high frequency. My problem is Red Book Standard has a hard filter in the low 20Ks and even in my youth, LPs I owned didn’t go super high either.
Actually, the 100+kHz recognition appears to be limited to few individuals. (Those who can hear bats...). Sadly true, HF starts dropping with age, although the process can be slowed down or mildly reversed when much effort is placed on it. (Protect ear from loud noises at work, home an commute, plenty of hydration and sleep, vitamin C...)
My father can hear the "youth jammers" (they place extremely high frequency spakers to drive off kids hanging around at places) they use at 60+. So it really is from person to person. Supposedly nobody over 20 can hear them. Scientifcally proven.
Ever since he went legally blind his hearing got even better. He can hear extremely well.
I can hear those damn high pitched sounds they use to drive off kids too. I am 38.
Anywhere to find the 288? Or something similar?
Great Plains Audio sells them.
Have a pair!
GPA still makes it, but they've been closing business on / off during the past years. The used market would be the only source. Very easy and cheap to find in California, expensive on ebay, almost impossible elsewhere. Other alternatives: EV (DH1A) or JBL (various models).
Why the trash in background?
Sabotage. Unreal.