Ported v sealed

[Kevin Dean]

If you had two identical cabs   but one was ported & the other sealed what would be the main difference between the two ?

[Chopthebass]

I'd be keen to know whether there is a difference to the listening audience. I have only ever had ported cabs and the extent of my knowledge is that the air movement from the port makes my trousers flap.

I hope Bill Fitz can give a good simple explanation.

[Bill Fitzmaurice]

Can you read SPL charts? This compares response of a Simplexx 15 sealed and ported with the Eminence BP1525 driver.

Note that if you want to get the same response from the ported as sealed you can, just back off on the bass EQ, which also reduces power draw from the amp. The chart only extends to 200Hz because above that they're identical. The ported advantage in low frequency sensitivity is there, but it's not huge. Now consider this, a maximum SPL chart, which takes into account the response, the driver thermal power handling and driver excursion limit:

The sealed cab doesn't even come close down low. The difference is attributable not only to the output added by the port but also the reduction in cone excursion that porting results in, and it's excursion that primarily limits how loud a cab will go below 70Hz or so, not the thermal power capacity. You can get a ported cab to sound like a sealed cab, but you can't get a sealed cab to deliver the low end output of a ported cab. There will be those who say otherwise, but in controlled double blind listening tests when EQ'd for the same response listeners are unable to tell the tone of one from the other.

[Kevin Dean]

The reason why I asked is that  I use to have a ported Ashdown ABM Neo  1 x15  I gave it to a charity a few years ago . I ordered  another one a few weeks ago & It's a sealed version  , Ashdown have given me dimensions of the two circular ports if I want to add them . They have told me that it will make it louder but not deeper & that has confused me a bit as I remember it sounding deeper ?

[Lozz196]

I`ve recently had the port on my ABM410 closed off. I spoke to Ashdown about what I was after, as the cab seemed too "wampy" and backing off of the bass, although getting there, wasn`t getting as near as I wanted. They suggested closing off the port so last week I stuck a towel in the (front) port. Instantly the sound I want was there, tight and focused, it really made that much difference. Previously, using my Para Driver as my main eq I still had to use the eq on the amp to back off the lows and up the high mids, now I have the eq on it bypassed using only the Para Driver.

[Bill Fitzmaurice]

4 minutes ago, Lozz196 said:

I`ve recently had the port on my ABM410 closed off. I spoke to Ashdown about what I was after, as the cab seemed too "wampy" and backing off of the bass, although getting there, wasn`t getting as near as I wanted. They suggested closing off the port so last week I stuck a towel in the (front) port. Instantly the sound I want was there, tight and focused, it really made that much difference.

That tells me the drivers used probably weren't well suited for a ported cab. Some drivers can be used either way, but most are optimized for either one or the other. You probably could have arrived at the same result with EQ, but it's likely the level of EQ sophistication required wouldn't be found in a typical bass amp. The one thing about sealed that ported can't duplicate is the low frequency compression that results when drivers in a sealed cab reach xmax, which may or may not be desirable based on personal preference.

[Deedee]

I don’t know too much about the science behind them, but I’ve just purchased a Bergantino NV115 sealed cab.  Used it for the first time on Saturday night and it sounded fantastic, clear, punchy and exactly how I’d hoped it would sound.

I was/have been trying to replicate the bass sound I have in my head which is that of a Trace 1x15 cab paired with a 2x10 cab but obviously in a smaller package.  This Berg to me is the closest I’ve ever gotten to it without hooking up the real thing.

Now this is the bit I don’t understand.  Why does a modern take on a sealed cab replicate the sound of two old Skool ported cabs so well ? 🤔

Edited March 19, 2018 by Deedee

[Bill Fitzmaurice]

Knowing the driver specs and cab particulars the science would reveal exactly what both of those set ups would sound like.

[Deedee]

50 minutes ago, Bill Fitzmaurice said:

Knowing the driver specs and cab particulars the science would reveal exactly what both of those set ups would sound like.

Here goes, I think these are correct:

 

Trace Elliot 2103h

2x10 with horn

Impedance: 8 ohms 

Frequency Response: 50Hz - 6kHz

Dimensions: H 610mm (24.6in) W 480mm (16.9in) D 430mm (16.9in) Weight 31kg 

Power 200 watts max 

 

 

Trace Elliot 1153

1x15

Impedance: 8 ohms 

Frequency Response: 32Hz - 5kHz. 

Dimensions: H 610mm (24.6in) 

W 480mm (16.9in) 

D 430mm (16.9in)

Weight 1153- 27.1Kg (59.7 lbs)

Power 200 watts max 

 

 

Bergantino NV115

• Woofer: 1-15” Ceramic Magnet Woofer w/ Vented Pole Pieces
• Midrange: 1-6” Intelligibility NV Series Cone Midrange Driver
• Cabinet Design: Sealed
• Cabinet Material: Baltic Birch Plywood
• Cabinet Covering: Black Tolex
• Impedance: 8-ohms
• Power Handling: 400W RMS
• Crossover: Custom Phase-Coherent Crossover
• Frequency Response: 45hZ – 6.5KhZ
• Sensitivity: 96db @ 2.83v / 1-meter
• Dimensions: 24”H x 18-1/2”W x 15”D
• Weight: 53 Lbs.

[Bill Fitzmaurice]

Those aren't driver specs. This links to an example of what a spec sheet looks like:

http://www.eminence.com/pdf/Kappalite_3015.pdf

 

 

[VTypeV4]

I believe the O/E Trace drivers were both variations on standard Celestions of the day - I owned both the 2103H and 1153 for a time..

The 10" is a 16 ohm C10H - a variation on the old BG10-80 model albeit with a larger magnet which may (or may not) change the spec compared to that of the standard model. And the 15" is a C15H which is essentially K15T / H with a slightly different cone / dust-cap and possibly a few other detail changes - again how much difference over a standard K series it is, I don't know. 

Celestion are generally pretty helpful with their older range - I've had plenty of info from them in the past so hopefully somewhere in their archives are the T/S specs for these older units..

As for the tuning of the Trace cabs, I can't recall the depth of the port - I think they're 8" maybe 10" deep by 4" dia although someone would have to check if they wanted to run the numbers accurately. I seem to remember something in one of the old manuals about there being bungs available to block one or both ports to alter the characteristics of the cab. Both open 45Hz, one open for 35Hz or maybe the other way round? Seems a bit daft to tune so low - neither cab would do anything close to 45Hz (from memory at least) let alone 35 although they were both great sounding boxes.

As for the Berg cabs, I can't comment as I know nothing about the model or the drivers they use..

[Kevin Dean]

Interestingly the ports on the  ABM Neos have no depth at all  just two round holes  next to each other , Having looked at some old TC  cabs  does it matter if the holes are next to each other or not ? 

 

[Lozz196]

12 hours ago, Bill Fitzmaurice said:

That tells me the drivers used probably weren't well suited for a ported cab. Some drivers can be used either way, but most are optimized for either one or the other. You probably could have arrived at the same result with EQ, but it's likely the level of EQ sophistication required wouldn't be found in a typical bass amp. The one thing about sealed that ported can't duplicate is the low frequency compression that results when drivers in a sealed cab reach xmax, which may or may not be desirable based on personal preference.

I think you`re on to something there Bill. I`d always loved the punchiness of the ABM610 & 810 when I used them, wondered why the 410 didn`t have the same sound, but last week was told that both the 610 & 810 are sealed - and the blurb on the site seems to indicate that the same speakers are used in all of the cabs.

[Deedee]

7 hours ago, Bill Fitzmaurice said:

Those aren't driver specs. This links to an example of what a spec sheet looks like:

http://www.eminence.com/pdf/Kappalite_3015.pdf

 

 

Ah, thanks for that.

To be honest it was just a general question for my own interest as to how seemingly very different cabs can sound similar (at least to my ears).

All I know is that I’m very happy with the sound I’m getting from the Berg 😁

[lojo]

14 hours ago, Lozz196 said:

They suggested closing off the port so last week I stuck a towel in the (front) port. 

Thats the next Gas item craze sorted , "Port Towels" 

Edited March 20, 2018 by lojo

[Bill Fitzmaurice]

4 hours ago, Kevin Dean said:

Interestingly the ports on the  ABM Neos have no depth at all  just two round holes  next to each other , Having looked at some old TC  cabs  does it matter if the holes are next to each other or not ? 

 

The position of the ports doesn't matter, but the lack of ducts does. Unless the cab is gigantic ducts are required to lower the tuning of the cab to where it must be for proper operation.

[Phil Starr]

15 hours ago, Lozz196 said:

I`ve recently had the port on my ABM410 closed off. I spoke to Ashdown about what I was after, as the cab seemed too "wampy" and backing off of the bass, although getting there, wasn`t getting as near as I wanted. They suggested closing off the port so last week I stuck a towel in the (front) port. Instantly the sound I want was there, tight and focused, it really made that much difference. Previously, using my Para Driver as my main eq I still had to use the eq on the amp to back off the lows and up the high mids, now I have the eq on it bypassed using only the Para Driver.

If you look at Bill's graphs it's fairly easy to see what is happening. Stuffing the ports to block their output cuts the deep bass by 3dB roughly. Cutting the bass makes everything else clearer, just as rolling off the treble makes your bass 'bassier' on top of that deep bass often sets off room resonances which can muddy the sound. We don't hear those very low frequencies that well anyway so don't miss them that much, in our studio recordings recently I cut everything below 50Hz form the bass, you could barely hear the difference on the isolated bass (sadly the filter added no talent) but it cleaned up the overall mix nicely especially on the sort of small speakers potential bookers are likely to listen to. You'd think that the more bass the better, but it ain't always so.

15 hours ago, Deedee said:

I don’t know too much about the science behind them, but I’ve just purchased a Bergantino NV115 sealed cab.  Used it for the first time on Saturday night and it sounded fantastic, clear, punchy and exactly how I’d hoped it would sound.

I was/have been trying to replicate the bass sound I have in my head which is that of a Trace 1x15 cab paired with a 2x10 cab but obviously in a smaller package.  This Berg to me is the closest I’ve ever gotten to it without hooking up the real thing.

Now this is the bit I don’t understand.  Why does a modern take on a sealed cab replicate the sound of two old Skool ported cabs so well ? 🤔

Part of the 'sound' of the speaker, I'd argue easily the  most important part is how it portrays the bits we can hear well, the mids. It may well be the Berg does mids similarly to the Trace, so happy days. Equally it may be that the lack of deep bass is an advantage in terms of clarity and punch, as I've explained above. Bill's response curves are of the same driver in sealed v's ported cabs, it's quite possible to choose a driver and design a ported cab which will have a bottom end that rolls off in a very similar way to the sealed cab in his example. The bass handling of a speaker is the combination of both the nature of the driver and the design of the cab

16 hours ago, Kevin Dean said:

The reason why I asked is that  I use to have a ported Ashdown ABM Neo  1 x15  I gave it to a charity a few years ago . I ordered  another one a few weeks ago & It's a sealed version  , Ashdown have given me dimensions of the two circular ports if I want to add them . They have told me that it will make it louder but not deeper & that has confused me a bit as I remember it sounding deeper ?

The final part of the puzzle is that what we hear depends upon how our ears and brains work together to interpret sound. What we hear as bass is often sounds above 100Hz. Just turning up the mids and treble makes us think there is less bass. Our ears are so insensitive to 30Hz for instance that even if the speaker is good in that area we won't notice a 30Hz filter because all the other sounds in music drown it out anyway. It may well sound deeper if you port it and how it sounds to you and anyone else is what matters, not the output at one particular frequency.

In this case however I kind of see what Ashdown are saying but I don't think it's helpful. If you go back to Bill's graphs then that is what they are predicting will happen with your cab. The speaker won't be any different above 200Hz as Bill says so it won't be louder. In his first graph you'll see just a touch more bass around 80Hz which you will notice (the exact frequencies boosted will be different in the Ashdown) but you'll get better power handling in the bottom octave which Bill shows in the bottom graph, so when you turn it up you'll be able to make more bass noise before it distorts with the ports. I'd say it will sound bassier to you.

[Kevin Dean]

Some years ago I had to replace a 15" Black widow bass speaker in a PA Sub  & even though the ohms & wattage was correct  it turned out there were several different designs & model numbers to choose from the difference  sound / performance was huge .

Edited March 20, 2018 by Kevin Dean

[Deedee]

Many thanks guys, I think it’s finally starting to make some sense 😀

[Kevin Dean]

I'm about to cut some holes ..wish me luck

Edited March 20, 2018 by Kevin Dean

[pfretrock]

Is this any cop?

http://www.tolvan.com/index.php?page=/basta/basta.php

[Kevin Dean]

It now sounds just how I wanted it to more thud ,funnily enough it sounds the same as my 4x8 but thatstoo heavy for me .

[JohnDaBass]

Kevin,

Now you have got the speaker out of the cab, and with your trusty cordless screwdriver to hand 😉, you may as well line the inside with some acoustic furry stuff to dampen the cab even more!

[Lozz196]

4 hours ago, JohnDaBass said:

Kevin,

Now you have got the speaker out of the cab, and with your trusty cordless screwdriver to hand 😉, you may as well line the inside with some acoustic furry stuff to dampen the cab even more!

The guy I dealt with recommended that I do this on my cab, said it would really tighten things up. I`ve used the cab this eve and it sounds great though, so coupling this with my natural laziness means I`m holding off on damping the cab at present, think it was Dacron he advised to use?

[Kevin Dean]

2 hours ago, Lozz196 said:

The guy I dealt with recommended that I do this on my cab, said it would really tighten things up. I`ve used the cab this eve and it sounds great though, so coupling this with my natural laziness means I`m holding off on damping the cab at present, think it was Dacron he advised to use?

Yes I don't think mine needs it , I really like it how it is , My old Barefaced cabs had quite a bit in them though ?