Balcro

Hi DanDare, Agreed, yes. I understand your comment, but in this case and at this stage all you need are the externals from which you deduct 18mm per panel with a small extra allowance for the front baffle recess. It's simpler for the OP rather than breaking out the screwdrivers etc. As winISD auto-calculates port length from a given port diameter, the existing port will have to be accepted as part of the calculations. I don't expect the final advice will give a 100% solution, but it could be 95% plus. PM to bigevilman.

Good morning Joe, As it sounds like a total loss, you'll need to give the forum some measurements:- the cabinet external height, width & depth. Then measure the diameter of the port at the back. Do that and then get back to us here. From that we can give you the best advice.

To echo Phil Starr, the FANE Sovereign Pro 8-225 is the best fit I've seen for a cabinet of about 18 litres net volume. It models in winISD very well. It's not 100% but I'd say it's 95%. Bear in mind the impedance change from 4 to 8 mentioned above, but otherwise it's definitely a get-out-of-jail choice. A quick search showed Blue Aran selling it for 2 different prices - one at £46.84 and the other at £56.88, depending upon the day in question. Fitting in your speaker cab depends on the frame shape, the overall diameter and the diameter of the fixing holes. Some older models appear to have shaved sides to the frame. See here for dimensions. https://www.fane-international.com/downloads/FANE-SOVEREIGN-8225-DS141117.pdf By the way, if you look at the data sheet - see the General Specifcation section which shows how "power handling" can be inflated! Your unknown original speaker is in fact only rated at 175w - it depends which website you're looking at.

No .1 Do as Phil Starr says. Just because it says 300W on the speaker does not mean the speakers will handle 300 W down to zero. Many a speaker will have a power capacity that dips in the 50-70Hz range; it depends upon the overall speaker design and the drive units. The Vanderkleys may well have no dip - no one can be sure. There may be a minor fault somewhere on the amp or the speakers. If the illustration on Gear for Music is accurate than you have the facility to radicaly reset the eq. Turn off the "Bass boost" switch and cut the bass down to -15. 2. Leave the Low-Mid Bass Range set on 165. Re-start & test, with the emphasis on getting the low-mid settings right - slowly increase the level. 3. Likewise with the High-mids. Set the range anywhere between 600 & 1K; re-start, test & adjust. 4. Presumably the "Enhance" switch works in the middle-upper range. Check the manual. Start with it off and slowly increase but without causing the clip light to function. 5. Slowly bring the Bass level back up, but not too much. Minus 12, minus 9; Try it & see the result. Good luck.

Ah! The Acoustical Resistance Unit. I seem to remember this being linked to a Goodmans catalogue. The idea being that it gave a smoother low-bass roll-off than a ported enclosure with a touch more extension. The odd hi-fi brand also made use of the idea. Celef Audio was one. Specific size was not as precise as a port for tuning. If you had an 18" speaker then you probably needed a 10"x10" ARU; smaller hi-fi style speakers only needed a 6"x 6" or even smaller. You can still get them today - SEAS the Norwegian hi-fi loudspeaker manufacturer offer a small round version.

THanks for that. Balcro

Another question for Bill. Can you expand upon your meaning of passband. I've looked up the meaning of "passband" but it can be a very wide or very narrow range. In respect of a single bass driver, when you said "within the passband at full excursion" do you mean from the low point where xmax is reached up to the top of the range or is there some other range of frequency response. Thanks. Balcro.

THanks Phil, I take your point about the problem with multiple ports. There's probably some deep turbulence / friction physics going on there, because the addition of more ports seems to be increasingly non-linear where resultant port length is concerned. I've just tried adding some filters to a specimen frequency response and the difference can be dramatic. Air Velocity was reduced from 20 down to 13.2 @ 40 Hz and the reduced Cone Excursion below 35Hz was even better. A definite alternative solution for chuffing, particularly in small boxes. Two bonuses for the price of one. Balcro.

Thanks Bill, It looks as if I am in the right area with 18 M/S in the pass band. Balcro

When modelling speaker drive units in winISD I understand that to avoid Port Chuffing you should keep Air Velocity below approx 18 M/s. Mostly, higher Air Velocities occur down at 22 - 35Hz or so, while the level @ 100Hz usually stays at about 3 - 5 M/s When modelling, I would set the input power level to either full rated power throughout the response range (for those units that can achieve it) or at the bottom of the traditional power-handling "60Hz dip" so that "xmax" is not exceeded. What would be good / best practice? Any comments, technical or otherwise. Balcro.

AUDACITY - If you haven't already done so, you need to install the "lame" encoder for Audacity. Go here :- https://manual.audacityteam.org/man/installing_and_updating_audacity_on_windows.html#winlame Once up & running, Import the FLAC file --> Select "Export as MP3". When "Save" dialog box appears with "Format Options", select "Insane" or "Extreme" quality. Other options:- Ashampoo (ashampo.de English) - Music Studio 2018 - the free version should do it. Alternatively, Music Studio 6 or 7 - short term trial versions.

Hello Douglas, Having put your supplied figures through winISD I would say you have a workable solution. The finished speaker will be more than loud enough for home practice or even a jam in the garage with a mate. That level of loudness will be achieved by only putting in 50 watts! So your amp will be cruising nicely. If you can get one round plastic pipe of about 3" internal diameter and 2.8" long, that will do for the port. Alternatively, two 2" ports of 2.5" internal diameter will work with a length of 5.1". In both cases the tuning is at 59Hz. If you can confirm the port sizes you have to use, (your pipes in the USA may be different to ours) then I can tell you the required length.

As Bill said, there are many considerations involved. First of all, think about closing up the back panel. Download and install the latest version of winISD - see Bill's link. Then post the information you have on your chosen 12" bass unit. Once the model and/or it's details (Theile/Small parameters) are visible, then a number of people on here can let you know whether it's suitable for bass and suitable to fit in a 30litre enclosure.

Hi LukeFRC, I can confirm chienmortbb's (Tuesday post) earlier estimate of "how loud it will go". Just ran winISD in auto mode - it sets the volume @ 69.81 litres. The following are basic & theoretical figures without fine tuning, nor is there reference to the actual volume of stevie's cab:- 165w input gives a maximum SPL of 119dB from 80Hz upwards!! xMax is only exceed below 37Hz at which point the output is 108.5dB. There's no arguing with stevie's assertion that "this cab will certainly go as loud with your amp as any other 12" cabinet out there." No discernible difference in output between 165w & 300w - the graph lines overlay each other. Putting 2 drivers in - just for fun- & upping the volume to 130 litres (still with 165watts) gives a potential 124.7db!! Balcro.

Mike Shrieve giving it his all on the biggest stage. One of rocks' magic moments and my favourite Woodstock clip. New Santana CD's sitting 4' away ready for Christmas wrapping.

Hi paulbuzz, I've re-done the responses with the 3 drivers, on the basis of a 17.2 litre enclosure with the port length unchanged at 12.5cm. This gives you clearest comparison. If you alter the port length it means cutting wood and damaging the enclosure. There are many variables involved because none of the drivers are an immediate best fit. To work with the port length, some of the drivers will need to have adjustments to the port area. In all three cases, at 100watt input, things don't look too bad, but change the input to 200watt and things start to get out of control. Frequency response around 100-150Hz pushes the response curves into exaggerated peaks, the port ventilation requirements increase to a point where "chuffing" might occur and the requirement for the vent area can exceed the available size. Of the 3, the Eminence is the least adaptable. Push up the ventilation to reduce port noise and the power handling suffers. It's not a bad drive-unit, I just think it's the least suited to this enclosure at 200w input. Of the other two, the 18sound is marginally better than the Celestion: 50 watts more power-handling down to lower frequencies (54Hz compared to 72Hz for the Celestion). The response curves around 125Hz are similar. In practice (and for both drive-units) I would think the latter difference could easily be eq'd out by cutting the bass a touch. If there's a "middle" control, boost that a little. If more reserve is your requirement, then it's the 18sound. At 200watts both drive-units are pushing the likelihood of "port-chuffing" but you'll be so loud you probably won't hear it - see last para. No 100% solution with either the Celstion or the 18sound. Looking at winISD, you have to assume it gives you the complete picture, and there's an ideal bass response which you'll like, but what's the original like?! It could be far inferior in terms of even frequency response or how it presents in winISD, but might still sound very impressive. Putting in one neo-dym speaker will probably only save you 1Kg. Without a full specification on the original no one can say the replacements will be sound better or louder (winISD @ 200watt input is predicting a sound pressure level of around 116dBa for the 18sound ) (you want to get louder?) and as Bill Fitzmaurice has said, you won't get extended bass in that small box.

Hi paulbuzz, I'm working on it. Comparison pictures up later - we've got plumbers in at the moment - Original assessments from last year and the new 18sound driver have had to be adjusted for maintaining the port length of 12.5cm. The 18sound is looking very good. More later.

Hello Geoff, Do you have a problem? Balcro.

What Dood said. Seconded. Check out this Q.Acoustics 3020 in Matt Graphite - bargain at Richer Sounds - https://www.richersounds.com/hi-fi/standmount-speakers.html Search online for reviews of the same. Learn it's strengths and it's weaknesses, but I think it's a good place to start. The whathifi.co.uk site also does a lot of reviews. PS. I don't own anything Q Acoustic.

Hi stewblack, Looked at the pics and listened to the sound. It looks like the solder joint has been repaired once before. With every movement of the cone back & fore, that small plate is going to constantly vibrated. A physical repair by gouging out the top of the broken rivet (watch those fingers!) might be possible. Loosen the top piece of the rivet with whatever comes to hand and then finally remove it with pliers; that should avoid any metal pieces falling into the "back of the cone space". You could then pass a piece of wire through the rivet / hole and twist it tight to secure the plate. The solder joints where the inner speaker wire is looped through a hole and then bent round the lug don't appear to be soldered , so give them a good squeeze with some pliers and then apply solder to both joints. After that try the sound test again. If that doesn't improve things then push the cone back and fore, as Twincam said, to see if there's a rubbing sound or unusual roughness. Balcro.

The usual advice in cases like this is try the simplest stuff first. Remove the grille or front cover if possible and check the speaker-unit securing nuts or screws. Undo the nuts and remove the speaker carefully, taking care to disconnect the speaker wires as you do so. Check inside - anything looking loose or unglued? Is the speaker rear connection panel secure? After that, you can post here with any details you can find printed or stamped on the defective drive unit. It may be an inexact replacement from an original. Tell us the speaker type; 1 x12, 2 x10 etc. Measure the the internal dimensions of the box as well as the diameter and length of any ports. Picture (front & back) of the croaking unit are often useful. There are a few likely lads on here who can tell you all sorts of things from pictures of the speaker and the code numbers. Replacement speaker cones and repair kits are available but the option to repair is usually governed by the cost of a new unit. There are several places to buy new units and as usual a number of us here can do all the calculations for fitting a suitable speaker. Post in the details as above, and we'll take it from there. Balcro.

More graphs....

Thanks for the correction on the parameters Phil. Lesson for today - always go to the manufacturers website. The Thiele / Small parameters on the Blue Aran web-site are nearly all wrong! Where they got those figures from I don't know, but they don't seem to found on any of the models in Beyma's new CMV2 series. The CMV2 is marginally weaker on power handling through the overall frequency bandwith, but the difference to the the SM212 is quite small. With both models assessed on a 200 watt input & in a 50 Litre cabinet:- The sm212 - takes full rated power down to 37Hz. The 12" CMV2- takes full rated power down to 41.5Hz xMax in the low bass is only reached @ 35Hz whereas in the CMV2 it's 40Hz, a function of the SM212's capability of being tuned to a lower frequency. The sm212 was auto-tuned to 45.45Hz by winISD. However the CMV2 appears to have an extended frequency response up to 5 & 6K whereas the SM212 drops off quickly above 4K, so maybe that's the real intention. A cheaper bass-mid speaker rather than a pure bass. Balcro. PS. Attached Frequency Response curves. CMV2 in green.

I've just put the specs through winISD and it looks like an improvement on the SM212. It has the classic Beyma smooth bass roll-off and handles more power. It appears to be very flexible in it's cabinet volume requirements and maybe requires fewer vents / ports. This maybe a case of "what's not to like"! I'll put some graphs up tomorrow. Balcro.

Hi stewblack, Phil Starr or Stevie can probably verify if this idea is acoustically practicable, but I think there may be an alternative to putting bricks inside the cabinet to reduce the volume. You could get hold of or scavenge some rigid polystyrene blocks ( packing pieces) such as these. https://www.amazon.co.uk/Small-White-Polystyrene-Sheets-Boards/dp/B0164QUZN0/ref=sr_1_6/258-6901820-1773340?ie=UTF8&qid=1536417827&sr=8-6&keywords=polystyrene+blocks If my maths are correct, each sheet takes up 6 litres. The average brick occupies about 1.75 litres so there's plenty of scope to save weight. Balcro.