I have in my possession a mid-fifties consolette, I have brought it back to life, AM receiver and all and she sounds stunning, but of course, two nearly 70 year old 8 inch oxford drivers can only do so much down low. I've modeled nearly every conceivable vented, closed, and horn type I can come up with, and can still only achieve a modeled flat response down to about 100hz, give or take. I would like to enjoy my listening sessions without having to lower the bass pot to save these poor dear old drivers on the few bass heavy tracks in my collection. Inasmuch, I've decided a powered subwoofer is in order, and have decided to incorporate it directly into the console, to keep the existing footprint and the wife approval factor.
I was wondering if it would be better, sonically, to apply a high pass filter to the woofers to protect them, or a band-pass, and full crossover redesign, giving the tweeter more range to play? Mind you, cost on this project is absolutely ZERO object, as this one is to be kept and enjoyed for some time.
I was wondering if it would be better, sonically, to apply a high pass filter to the woofers to protect them, or a band-pass, and full crossover redesign, giving the tweeter more range to play? Mind you, cost on this project is absolutely ZERO object, as this one is to be kept and enjoyed for some time.
Rel makes some pretty good subs. Mine have a back panel much like this:
They are made to be adjustable to dovetail in with existing speakers.
Some info on how they recommend to tune the subs: https://rel.net/blog/2015-07-23/tuning-guides/how-to-tune-a-rel/
Maybe some of that will give some ideas. Hopefully so 🙂
They are made to be adjustable to dovetail in with existing speakers.
Some info on how they recommend to tune the subs: https://rel.net/blog/2015-07-23/tuning-guides/how-to-tune-a-rel/
Maybe some of that will give some ideas. Hopefully so 🙂
Attachments
Not to nitpick, Mark, but you seem to have completely missed the mark on this. I understand how to turn a pot to tune the crossover frequency on the sub. My question isn't about tuning the sub to my system, but on protecting the irreplaceable drivers from attempting to reproduce frequencies well below their designed operating range at high volume. Take an 8" alnico woofer, on an open baffle and start playing bass test tracks at 95dB, frequencies below 120Hz or so begin to distort as the driver reaches xmax, impedance maxes out and it flat out struggles.
But I like it loud. I can't fathom turning it down, so I must protect the original drivers.
But I like it loud. I can't fathom turning it down, so I must protect the original drivers.
Assuming this is a typical console with a record changer, adding a subwoofer internally will create substantial cabinet vibrations, resulting in annoying feedback issues when playing records, particularly at louder volumes.
I'm not speculating about this, trust me, because I've serviced and modified hoardes of consoles for customers, old mono, and stereo, and have my own consoles.
So, opening up a can of worms will soon raise it's ugly head.
Better to use a sub away from the console, unless you want to get involved with adding a subsonic (Sallen-Key) filter to remove anything below 20 or 25 Hz, which is what I did to my consoles.
I'm not speculating about this, trust me, because I've serviced and modified hoardes of consoles for customers, old mono, and stereo, and have my own consoles.
So, opening up a can of worms will soon raise it's ugly head.
Better to use a sub away from the console, unless you want to get involved with adding a subsonic (Sallen-Key) filter to remove anything below 20 or 25 Hz, which is what I did to my consoles.
Okay. It would seem reasonable to HP filter the existing woofers in order to help protect them. The question would then seem to be at what frequency and the most suitable roll-off rate?
I added a sub to my mom's tube console back in the 70's. It was just 3 passive resistor-capacitor stages into a Knight-kit amp. You could add a gentle 6dB roll-off, but more would probably color the sound. Especially old tube amps with output transformers have a natural bass roll-off. There will be no 10Hz coming out of an old tube amp like that. This is because 1. the transformer inductance is limited so it ~shorts the bass and 2. feedback is minimal if any that would prop up the bass. The other thing is that small driver back EMF is about cone movement and not acoustic output, so even a flat input produces a bass roll-off sound.
Change the component! It has already gone back and forth millions of times and probably it's tired!
Then... tweeter? Again, make the step to the novel technology.
Is the grill cloth a problem?
Wise, the sub-sonic filter was on my mind as well, and mind you, I'm not talking about up and stuffing a 1000 watt amplifier and 15 inch servo into the cabinet, but more realistically, a 25 watt plate and modest modern woofer of about 6.5". Cabinet resonances will be taken into consideration. As far as vinyl goes, I don't intend to use the record player currently, functional as it is, since it's a crystal cartridge, and HEAVY tonearm assembly from 1955, good for a few spins but probably not my good albi. Not that it doesn't sound good, but that's a project for another day.
Pico, why change something, if you like something? Everything else about the drivers are fine. I have auditioned newer drivers and found them lacking in similar presence. Not to knock ferrofluid woofers and space blanket folded ribbon tweeters that get destroyed anytime I open the front door on a Tuesday. When it's time, I'll bite the bullet and be out of service while I recone the original drivers for another 70 years of service.
I know you like 'em but still, those cannot produce the thing you want.
The choice Is to make an Aid and take the Dangerous band out of them, or change 'em.
The choice Is to make an Aid and take the Dangerous band out of them, or change 'em.
I appreciate new technology as much as the next guy, and wish to incorporate said technology in ways that don't interfere completely with history. Take a classic Jaguar, for example, can be turbocharged, and disc brakes added for a performance upgrade, or you can yank out everything that made a Jag a Jaguar, and drop in a crate 700 horsepower Hellcat motor and have ended up completely destroying the essence and sophistication that was the blissful inline six.
I own things outright. What I own I repair. What I don't know I learn. If I fail, it won't be the same way twice.
I own things outright. What I own I repair. What I don't know I learn. If I fail, it won't be the same way twice.
Yes, you are right...of course...the creative stage Is up to you. For car analogies, I'd Say it's like you have a broken First Gear and you cannot climb or start to run, either...
But as Steveu wrote, One has to consider the merits of the amplifier. Probably a complex load stresses too much, the EMF could be too high.
About changing the speakers and their lifetime job, I was refering to the spider and the external suspension, not the VC.
But as Steveu wrote, One has to consider the merits of the amplifier. Probably a complex load stresses too much, the EMF could be too high.
About changing the speakers and their lifetime job, I was refering to the spider and the external suspension, not the VC.
Subwoofer incorporated directly into the console is a bad idea, as @wiseoldtech explained earlier. Any active subwoofer can be placed in the room to be unobtrusive to the eyes.
Use 2nd-order (C-L) passive high-pass filter for the 8" driver - it requires big inductor and capacitor. Or, easier to do - make line-level passive CR high-pass filter.
I suppose tweeter filter is just a single capacitor, so a proper 2nd-order (C-L) or 3rd-order (C-L-C) high-pass filter would be better.
I think that the tweeter Is Just a 3" paper cone, so air resistance makes the rest, i.e.'bracking' the membrane
Having thought about it a little more, it might help to reframe what it is you actually want. IOW, how much protection of the woofers do you want? Do you want them to never hit a mechanical limit, or is it something else? If they are never to hit the end of their travel then sweeping with one frequency is not necessarily the worst case.
Pico you are correct it is a paper cone 3.5" sealed back driver providing the high frequencies.
Mark, as far as what type of protection I'm looking for for the original woofers, I'm talking about preventing low end distortion with the woofers at high volume, by filtering frequencies lower than 120hz. Thus preventing the over excursion that causes distortion at those low frequencies and high volume levels.
I'll restate my original question. Sonically, would it be better to filter out low frequencies to the woofers with a high pass filter, or a band pass filter, reducing the woofers contribution to HF?
Mark, as far as what type of protection I'm looking for for the original woofers, I'm talking about preventing low end distortion with the woofers at high volume, by filtering frequencies lower than 120hz. Thus preventing the over excursion that causes distortion at those low frequencies and high volume levels.
I'll restate my original question. Sonically, would it be better to filter out low frequencies to the woofers with a high pass filter, or a band pass filter, reducing the woofers contribution to HF?
Aren't there multiple factors involved? Suppose there was a loud 120Hz music component combined with a high crest factor 2nd harmonic. The combination of frequencies might distort when 120Hz alone might not. Using a bandpass filter might reduce the chances of something like that happening, but it introduces other questions about possible effects to the overall sound.
May I ask if all your audio is digitally processed, or is some or all of it purely analog?
May I ask if all your audio is digitally processed, or is some or all of it purely analog?
I listen to mostly digital sources lately, cD, DVD, FLAC. More analog to come when I go through the reel to reel. Analog sounds absolute best, then AAD recordings, when I get into the ADD and modern purely digital recordings, there feels like zero headroom on the low end as if bass were maxed out and compressed to within an inch of it's life.
It might be possible to insert some processing into the digital signal chain that is a low frequency peak limiter. Or at least a low frequency peak detector. For one example of people doing such things, many professional class-D power amps have built-in DSP that offers compression, and or limiting in different degrees with different detection thresholds, compression ratios, etc., to softly start limiting driver power gently at first, then as strongly as needed to protect the driver. Something like that might be too extreme for home use, however I could imagine routing digital audio through a VST plugin such as 'Waves L2' lookahead peak limiter (IIRC there is also a multiband version of the limiter, so LF could have its own setting). It will show you how close you are getting to the limit you set. For mild limiting it is pretty transparent. I could also see testing the system for distortion with a LF yet high crest factor time-domain waveform to help establish a likely estimate of when distortion might occur with real music.
It might help if the consolette in question here was known. (photos, model number, speakers/chassis info, etc)
I've probably serviced one for a customer at the repair shop.
Also, since these things were designed originally for a certain quality of sound, making any modifications will certainly affect the original sonics.
The cabinet itself gives a certain flavor to the sonics, as panels resonate mostly adding "boom effect".
I've probably serviced one for a customer at the repair shop.
Also, since these things were designed originally for a certain quality of sound, making any modifications will certainly affect the original sonics.
The cabinet itself gives a certain flavor to the sonics, as panels resonate mostly adding "boom effect".
