Jump to content


  • Content Count

  • Joined

  • Last visited

Total Watts

34 Excellent

About Balcro

  • Birthday 08/12/1947

Recent Profile Visitors

1,063 profile views
  1. 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.
  2. 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.
  3. Thanks Bill, It looks as if I am in the right area with 18 M/S in the pass band. Balcro
  4. 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.
  5. 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.
  6. 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.
  7. 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.
  8. 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.
  9. 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.
  10. 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.
  11. 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.
  12. Hello Geoff, Do you have a problem? Balcro.
  13. 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.
  14. 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.
  • Create New...