Balcro

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.

Thanks for the info OP. I wouldn't touch a Red Bull if you paid me. Never thought that much caffeine was any good for you. Caffeine has it's place in medicine for speeding up the intake of drugs, i.e +varieties of paracetamol, but not for recreational "boosting". The one thing that will cause hearing loss on its own is Quinine, if taken in very large doses. A couple of bottles of Tonic Water will have no effect on the average person. Quinine used to be given to soldiers in the Boer & First World Wars as a preventative for Malaria but the doses were massive. Later, of course, it was found to cause the tiny hairs deep inside the ears to bend away from & not make contact with ( I think) the tympanic membrane. Damage was permanent. Maybe this is another ingredient to avoid if you already have a hearing problem. PS. another vote here for Yorkshire Tea Decaf!

The following link to the forum - first two entries - sums up the current situation - https://www.tapatalk.com/groups/unofficialacousticcontrolcorpmessageboard/ If you want the monster see "vetchking" o.n.a George Grexa. The forum people will probably tell you about reviews and voltages etc,. Search out any American amp review sites as well as talkbass.com

Hello fiatcoupe432, Sorry, "adledman" got there first followed by one other. I hope to have the second half the kit removed from the enclosure in this coming week, but unless "adledman" changes his mind then I have to acknowledge him as first person to request the kit. Regards, Balcro.

pm to adleman.

Done it at last - 2 tracks added. So many screens, so many log-ins, so many unhelpful help files and some 404's. In the end I think it was making my own playlist "collaborative". Then it worked on one screen.

Thanks for your help but it doesn't work. I tried that approach last night, but it only allows me to copy one of Dood's listings into my playlist. Spookily it even extracted 4 selections from my Amazon Music list and put them into a playlist on Spotify which I didn't know I had. Cheers, Balcro

Can't work out how to add to the playlist. tips anyone? Balcro

Very nice collection. For me, the standout is that lovely European Blonde upright. Enjoy. Balcro.

My venerable home built hi-fi speakers are to be replaced as it's a big x?0 birthday coming up. Nearly vintage hi-fi parts - well, late 70's - and all in good working order. Of late, they've been used about 2 or 3 times in a year. For lovers of something different, the drive units are a Shackman Electrostatic kit comprising of a Shackman Electrostatic mids/tweeter and an 8" Dalesford D.50 bass unit. Go search them out on the internet. I can provide a data sheet on the Dalesford. At the moment the bass unit is installed in a 30 litre box distributed-port cabinet and the electrostatic unit is mounted in a semi-open enclosure on top of the box. The crossover which operates @ about 500Hz, is incorporated onto the power supply board for the electrostatic unit. Yes, this thing is powered from the mains and has high voltages, so will need to be protected. Use of a small soldering iron will be needed. The bass unit will work in a much smaller cabinet if necessary and even in a closed - non-ported - cabinet. If you look at this video - (it's not mine) the electrostatic units are the small silvery curved things (about 8x6) on top of the other speakers. The overall sound is very clean with minimal colouration. Efficiency is low at about 84dBa per 1w, but the bass goes down a long way. It's not a party machine. ** It's yours, free to a good home for collection from SG1 or otherwise for the cost of postage & packing. As I'm "off-sick" at the moment, the kit won't be available until mid-December. PS. If you search on youtube for "Shackman Electrostatic" then scroll down the list until you come to the entry SRV, click on this for an aural treat.

As Bill says, "why not do it right the first time" or words to that effect. If you do it wrong, it might initially sound impressive because the speaker will sound louder, but at the same time you can dramatically affect the power handling & reliability of the drive-unit in the cab. Turn up the wick and snap, crackle, pop! Some drive-units will cope with the changes because they're versatile enough to "work" in both closed or ported cabinets. Many won't. It usually depends upon the internal volume of the box and the choice of drive-unit. Why not just ask the question "is it feasible"? On this forum, given the exact drive-unit specification and the volume of the box, I and several others can usually give you an answer in under an hour, but I suspect in most cases it will be negative.

First came across this while looking up turntables on youtube. One click led to another and then oooo.. I wouldn't have bothered normally, too many screeching guitarists to avoid, but this just has it. Stevie Ray Vaughan.. https://www.youtube.com/watch?v=zB10bRX0Hcw

Here's the frequency response curve -

Hello Sweeny... By my calculations the cabinets have gross internal volume of about 59 litres. The BL12 200x will work in that volume and give pretty reasonable results. Perhaps not optimum, I think the BL's need another 6 litres or so for that, but far from rubbish. It looks like they will give a slightly warmer sound than average(?). The curve dips down after 5-600Hz so there's room to up the mids and treble. I'll try and get a picture of a frequency response curve posted later today. Balcro.

Hi there, As Stevie says, either Celestion speaker will work OK in that box. By the way, my calculations are that it's 167 litres gross volume. Just one other observation. It's a square box 27 x 27". Having an exact square dimension might well cause some unwanted resonances, so it's best to pad out one side of the box with hard polystyrene blocks if you can get hold of some. They take up volume without adding any real weight. Two to three inches should be enough. For every inch in depth of poly blocks you'll lose about 5.9 litres in internal volume, but in this case it's all to the good. No significant difference to the frequency response.

After re-running the figures with the revised port length and a volume of 17 litres, etc., I agree with your general conclusion on the differences in response curves of the two drive units. The Eminence has the peakier / exaggerated response centred on about 135Hz while the Celestion is a flatter response by 2dB and centred @ about 115Hz. Marginally I would favour the Celestion. It might sound a bit less "one-note". Power handling for both units is well in excess of the original, especially in the low bass. The Celestion takes the full 250w rated power down to about 68Hz, the Eminence is similar except it has a dip to only 200 watts just around the area (125Hz) where it's output peaks. Balcro.

Hello paulbuzz, Can you please check the dimensions of the cabinet in your possession. Your written dimensions in the first post do not tally with the dimensions in the diagram. Balcro.

Thanks for the excellent diagram. I agree with your observations about changes to tuning & the frequency response. Yes, I am thinking of extending that lower shelf & reducing the 100mm gap. I shall re-calculate and give you the options. Will get back to you later. Balcro

Hi paulbuzz, The Eminence spec sheet is really very broad. When you put the Deltalite II specs into winISD, the automatic calculation produces a very flat frequency response at a volume of 60 litres. Reducing the volume to 30litres still gives a reasonable response curve, however when you check the "Maximum Power" chevron the result is a disappointing dip to 80w down at 80Hz. Reducing the volume to about 17litres tips the response sharply upwards in the low-mid bass, throwing the system tuning out. The Celestion still falls foul of the fixed slot port, with a tilted up frequency response, but not quite so much. To restore some sense to the situation you could retune the port quite easily. In other words reduce the 100mm gap at the back. Let me know the length of the slot port roof by measuring it's front-to-back internal length and I will recalculate. Balcro

I've had a look at this in winISD and it looks like the Celestion is definitely the one to go for. My rough calculation is that you have an internal volume (ignoring the slot port) of about 17.20 litres. This rules out the Eminence which would prefer at least double that volume. The Celestion handles 150+ watts all the way down to about 48Hz, while the original Elder Audio driver you have quoted (with a 50w input), dies at about 190Hz, bottoming out at 35watts on 90Hz! The Celestion goes louder for a given input and with it's larger xmax has much greater "headroom" at low bass frequencies. If anyone would like to cross check my findings I'm more than happy.

Nothing bad to say about them. Some of their prices can be surprising. I bought my Cort Bass from them 5 years ago. Prompt delivery in about 5 days as I recall. The credit card company made a call to me as the location flagged up as an unexpected usage location. That's was fine by me. Balcro.

It's best to start here:- [url="https://www.tapatalk.com/groups/unofficialacousticcontrolcorpmessageboard"]https://www.tapatalk...orpmessageboard[/url] There are lots of people on this forum who give you all sorts of information & answers about "Acoustic". This other link also looks interesting:- [url="https://acousticamplification.com/history-of-acoustic-amplification/"]https://acousticampl...-amplification/[/url] Then get over to youtube and see all the videos about the amp and the 360/361's. Then wikipedia. If you wan't to know the tone, see this - [url="https://www.youtube.com/watch?v=EGuEagHDL9M"]https://www.youtube....h?v=EGuEagHDL9M[/url] - he saves the best 'till last- play it loud! Balcro

There's a further complication to do with wiring and it bears on my comment about power handling. Do think about this before you decide to go ahead and bi-amp the 2 x10 cabinet with the 15" cab. See Phil Starr's post #22. Check the label on the side of the Deltalites and the 15"unit. It may make the mating of the 1x15 and the 2x10 even more impracticable. See search term "Power handling of a 2 x 10 speaker wired in series". Lots of answers, but as far as I can see you can only wire (in the case of the 2x10) 2 drive units in series or parallel but not in series/parallel. If you have any doubts, come back to the forum and double check with an Ohm wizard.