LewisK1975 Posted October 17, 2016 Share Posted October 17, 2016 Should have a two10 heading my way this week It's a 12ohm version and I'm looking at getting the stuff from BF to convert to 4ohm, which I'm led to believe is a relatively simple swap job. Has anyone done this? Does anyone know how much BF charge for the conversion kit? I have emailed them directly but no response as yet.. Quote Link to comment Share on other sites More sharing options...
skychaserhigh Posted October 17, 2016 Share Posted October 17, 2016 Ask them for some tolex glue while you're at it.....! Quote Link to comment Share on other sites More sharing options...
LewisK1975 Posted October 17, 2016 Author Share Posted October 17, 2016 [quote name='skychaserhigh' timestamp='1476706910' post='3156438'] Ask them for some tolex glue while you're at it.....! [/quote] Quote Link to comment Share on other sites More sharing options...
Barabass Posted October 17, 2016 Share Posted October 17, 2016 I've done the conversion. It's simple to do. BF sent me a clear manual, it's easy. Quote Link to comment Share on other sites More sharing options...
LewisK1975 Posted October 17, 2016 Author Share Posted October 17, 2016 [quote name='Barabass' timestamp='1476715583' post='3156570'] I've done the conversion. It's simple to do. BF sent me a clear manual, it's easy. [/quote] Cheers for that, do you mind sharing how much the stuff cost? PM me if you don't want to put it here. Quote Link to comment Share on other sites More sharing options...
LewisK1975 Posted October 17, 2016 Author Share Posted October 17, 2016 A quick google search showed a response on the Barefaced wesbite to the same question as mine - from August last year - the replacement loom to convert to 4ohms was £30. Cool. Quote Link to comment Share on other sites More sharing options...
LewisK1975 Posted October 19, 2016 Author Share Posted October 19, 2016 Yep - still £30. Ordered! Quote Link to comment Share on other sites More sharing options...
goingdownslow Posted October 19, 2016 Share Posted October 19, 2016 (edited) How do you convert a 2X10 12Ω cab to 4Ω with just a wiring loom, is it magic cable? Edited October 19, 2016 by goingdownslow Quote Link to comment Share on other sites More sharing options...
machinehead Posted October 19, 2016 Share Posted October 19, 2016 [quote name='goingdownslow' timestamp='1476882017' post='3158060'] How do you convert a 2X10 12Ω cab to 4Ω with just a wiring loom, is it magic cable? [/quote] Remember, we're talking overall cab impedence here and both speakers don't cover the same frequencies. Frank. Quote Link to comment Share on other sites More sharing options...
LewisK1975 Posted October 19, 2016 Author Share Posted October 19, 2016 [quote name='goingdownslow' timestamp='1476882017' post='3158060'] How do you convert a 2X10 12Ω cab to 4Ω with just a wiring loom, is it magic cable? [/quote] The 'kit' you get includes a wiring loom, crossover and rear panel. I guess the magic's in there somewhere! Quote Link to comment Share on other sites More sharing options...
stevie Posted October 19, 2016 Share Posted October 19, 2016 [quote name='machinehead' timestamp='1476888019' post='3158148'] Remember, we're talking overall cab impedence here and both speakers don't cover the same frequencies. [/quote] Yes, do go on. Quote Link to comment Share on other sites More sharing options...
machinehead Posted October 19, 2016 Share Posted October 19, 2016 [quote name='stevie' timestamp='1476890909' post='3158181'] Yes, do go on. [/quote] Oh I think you could explain it much better than me stevie. It was my day job for 43 years and I don't like talking shop. Frank. Quote Link to comment Share on other sites More sharing options...
MoonBassAlpha Posted October 19, 2016 Share Posted October 19, 2016 speaker impedance figures are only nominal, I wouldn't sweat it. Quote Link to comment Share on other sites More sharing options...
stevie Posted October 20, 2016 Share Posted October 20, 2016 [quote name='machinehead' timestamp='1476899510' post='3158314'] Oh I think you could explain it much better than me stevie. It was my day job for 43 years and I don't like talking shop. [/quote] Sorry to disappoint you, Frank, but I can't explain it either. It doesn't make any sense to me at all. The only thing I can think of is that the 12ohm cabinet isn't actually 12 ohms, but 16 ohms. It was a perfectly sensible question though. Quote Link to comment Share on other sites More sharing options...
LewisK1975 Posted October 20, 2016 Author Share Posted October 20, 2016 Found this on TalkBass from Alex, hope he doesn't mind me quoting this.. [color=#191919][font=Lato, Arial, sans-serif][size=3] [indent]Right, so the impedance thing. I know most bass players think a 4 ohm cab is 4 ohms all the time and an 8 ohm cab is 8 ohms all the time but that that couldn't be further from the truth! When designing a driver one of the first things you decide on is the target impedance. You then have this complicated juggling act of wire material and gauge, length of voice coil, number of layers wound, and then that gives you the total length of wire on the voice coil and thus the DC resistance of the coil. Changing any of these physical properties also changes the inductance Le, the magnetic force BL, the moving mass Mms, the maximum clean excursion Xmax, and the maximum excursion before permanent damage Xlim. Changing those parameters also changes the resonant frequency Fs, the total Q Qts, the compliance equivalent volume Vas, the EBP, the Vd, the calculated sensitivity and so on. It also changes the tone through the midrange and treble. So as you can imagine it's not a straight forward affair in the slightest! That voice coil then needs to be matched up with a suitable cone, dust cap, surround and spider(s) to create your driver model. Once you have your driver simulation you can then model the impedance and the low frequency performance. If both are in the right ball park then you make a physical sample and test it to see how it sounds/performs, particularly through the mids and treble (because you can't model that, it's too complicated - although you can certainly predict approximately what's going to happen if you've got a decent feel for how loudspeakers work and understand the parts you're using). Now the thing about the impedance is it's a very long way from a simple flat line - in free air you get a peak at resonance whose height and width depends on the resonant characteristics of the driver and then it starts rising at higher frequencies due to the inductance. Once you put the driver in a cab that changes the low frequency impedance because you're changing the resonant system. The DCR of your voice coil is lower than the target impedance because the driver exhibits both inductive and capacitive reactance both of which add to the DC resistance to create the actual impedance. When you first set out with your coil design you have to figure in how those two aspects of reactance will add to the resistance to create the impedance. You don't want to start out with too high a resistance and end up with your driver having excessively high impedance compared to the nominal target as that will cost you in voltage sensitivity but you don't want to have too low a resistance or you'll cause amp shutdowns (destructive failures are rare nowadays). Also you can't vary the DCR continuously - wire comes in specific gauges, winding layers are one, two, three or more and you can't stop halfway around a turn! And changing the gauge or layers drastically changes the BL whilst changing the length drastically changes Xmax/Xlim. There are yet more issues - impedance is a vector quantity with magnitude and phase. Inductive reactance pulls the impedance into positive phase angles whilst capacitive reactance pushes it negative. Negative angles are much harder for amplifiers to drive than positive. The DC resistive component of impedance varies hugely with temperature - impedance is quoted at room temperature but at full power your voice coils will be at around 200 deg C and your impedance will have doubled. We've generally erred on the side of caution (the higher side) with the actual vs nominal impedance of our new driver designs - why? 1. Gen 3 cabs are loud already so we don't need to squeeze extra watts out of your amp 2. Some Gen 3 cabs have complex crossovers which make them more challenging to drive due to shunt coils dropping the impedance and series caps pulling the phase negative. 3. The Gen 3 cabs have huge thermal power handling so they don't get as hot and increase in impedance as much when you're playing loud. 4. Our Gen 3 cabs have big well-tuned ports which act as a capacitive component pulling the phase negative again. The end result of this is that the Gen 3 12XN cabs are all nice loads to drive. The Retro 10CR driver was designed as a 6 ohm driver so our new 6x10" would be 4 ohms. The final driver design we settled on is a particularly easy load to drive with the minimum impedance in free air not dropping as low as the norm. The hybrid resonator enclosure further raises the average impedance in the sub 150Hz region. There is that added capacitance higher up though and it's a series crossover so it drops the impedance more than a parallel crossover would. Also with six moderately large voice coils there's a lot of thermal power handling and thus minimal impedance rise due to heating. With the performance and tone we were getting there was no need to try and squeeze the impedance lower for more voltage sensitivity so the Retro Six10 was left as a very easy to drive 4 ohm nominal load. The Retro Two10 is simply one third of a Six10. Hence the 12 ohm nominal impedance with one third of the drivers, crossover and wiring loom. I realise that designing around six 10" drivers is unconventional but it just makes more sense to us for use with old school / valve amps than the "rarely loud/fat enough" sealed 4x10" or the "usually louder/fatter than you need" sealed 8x10". Yes our Retro10 cabs aren't technically sealed but they're more like sealed cabs in terms of sensitivity than ported cabs. It may be a more difficult marketing challenge than selling an 8 ohm 2x10" but hopefully our target market will understand! So, finally back to the 4 ohm 2x10". After we put the Retro Two10 on our site there was quite a bit of impedance related discussion online and I went back to look at our various documents and measurements. And that got me thinking... Almost every valve or solidstate amp on the market will drive a 12 ohm nominal load very happily - the only exception I can think of are valve SVTs which have 2 and 4 ohm taps but no 8 ohm tap. If we parallel rather than series wire a version of the Two10 then SVTs can drive a single cab without worry. Therefore we could offer a lower impedance alternative for SVT users (a great recording or small gig cab!) Due to the parallel wiring we'd need a different crossover and this crossover would have no capacitive component (reducing the negative phase angle) and would also raise the magnitude of the impedance at mid/high frequencies. This means that the lower impedance version would be a particularly easy load for its nominal impedance - so I did some modelling of a variety of 4 ohm bass cabs on the market, particularly focusing on the impedance minima and the phase angle at those points. We compared our model of the Two10 low impedance version to those cabs and it came out very well, especially considering that a simplistic analysis would declare it to be slightly lower nominal impedance. We need to test what happens in practice with a variety of solidstate amps whose minimum load is 4 ohms but based on all our measurements, simulations and the comparisons with other bass cabs I think it should be fine and thus can be deemed a 4 ohm nominal design. Sorry, that got a bit long! [/indent][/size][/font][/color] [color=#717171][font=Lato, Arial, sans-serif][size=2][right]Last edited: May 14, 2014[/right][/size][/font][/color][color=#191919][font=Lato, Arial, sans-serif][size=3] [color=#717171][url="https://www.talkbass.com/members/alexclaber.17037/"]alexclaber[/url], [url="https://www.talkbass.com/threads/barefaced-69er-thread.823993/page-11#post-15894787"]May 14, 2014[/url][/color] [url="https://www.talkbass.com/threads/barefaced-69er-thread.823993/page-11#post-15894787"]#203[/url][/size][/font][/color][color=#191919][font=Lato, Arial, sans-serif][size=3] [/size][/font][/color] Quote Link to comment Share on other sites More sharing options...
stevie Posted October 20, 2016 Share Posted October 20, 2016 Thanks, Lewis. I get it. Quote Link to comment Share on other sites More sharing options...
machinehead Posted October 20, 2016 Share Posted October 20, 2016 [quote name='stevie' timestamp='1476950782' post='3158659'] Sorry to disappoint you, Frank, but I can't explain it either. It doesn't make any sense to me at all. The only thing I can think of is that the 12ohm cabinet isn't actually 12 ohms, but 16 ohms. It was a perfectly sensible question though. [/quote] Sorry stevie, I mistakingly thought you were teasing me just a wee bit. My thoughts were simply that the two cab versions were different in simply series or parallel connection and that each connection would require a diffferent crossover design (because the two10 speakers dont produce the same frequencies) and that, combined with varying coil impedence at a range of frequencies and other parameters could present the approximate 4ohm and 12ohm impendence at the cab terminals. I could see how that would be possible and hence my reply to goingdownslow's post. Frank. Quote Link to comment Share on other sites More sharing options...
stevie Posted October 20, 2016 Share Posted October 20, 2016 Perfectly logical thinking, Frank, but I don't think that's it. And I wasn't teasing you - I was genuinely interested in your train of thought. Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted October 20, 2016 Share Posted October 20, 2016 [quote name='stevie' timestamp='1476950782' post='3158659'] Sorry to disappoint you, Frank, but I can't explain it either. It doesn't make any sense to me at all. The only thing I can think of is that the 12ohm cabinet isn't actually 12 ohms, but 16 ohms. It was a perfectly sensible question though. [/quote] [quote name='LewisK1975' timestamp='1476953400' post='3158685'] Found this on TalkBass from Alex, hope he doesn't mind me quoting this.. [color=#191919][font=Lato, Arial, sans-serif][size=3] Therefore we could offer a lower impedance alternative for SVT users (a great recording or small gig cab!) Due to the parallel wiring we'd need a different crossover and this crossover would have no capacitive component (reducing the negative phase angle) and would also raise the magnitude of the impedance at mid/high frequencies. This means that the lower impedance version would be a particularly easy load for its nominal impedance - so I did some modelling of a variety of 4 ohm bass cabs on the market, particularly focusing on the impedance minima and the phase angle at those points. We compared our model of the Two10 low impedance version to those cabs and it came out very well, especially considering that a simplistic analysis would declare it to be slightly lower nominal impedance. We need to test what happens in practice with a variety of solidstate amps whose minimum load is 4 ohms but based on all our measurements, simulations and the comparisons with other bass cabs I think it should be fine and thus can be deemed a 4 ohm nominal design. [/size][/font][/color][right]Last edited: May 14, 2014[/right] [color=#191919][font=Lato, Arial, sans-serif][size=3][color=#717171][url="https://www.talkbass.com/members/alexclaber.17037/"]alexclaber[/url], [url="https://www.talkbass.com/threads/barefaced-69er-thread.823993/page-11#post-15894787"]May 14, 2014[/url][/color] [url="https://www.talkbass.com/threads/barefaced-69er-thread.823993/page-11#post-15894787"]#203[/url][/size][/font][/color] [/quote] I think he's saying it's 3ohms but that it doesn't matter much Stevie. Which it won't to be honest. He may also be saying the crossover adds an ohm Quote Link to comment Share on other sites More sharing options...
lownote Posted January 30, 2017 Share Posted January 30, 2017 (edited) I bought a 12/ 210, agonised over the conversion and bought (but didn't fit) the kit - too many people said try it as it is and only go to the faff of changing if its vital. Well, I'm keeping up with drums, lead, PA and organ and we're getting comments about our volume outside a commercial sound insulated studio and my volume knob is at 9.30 (MB LM2). So I add my voice to those who say don't bother. Plus Alex has told me by email that it's not that easy a job, in his words while not difficult technically it's a pain in the neck. Edited January 30, 2017 by lownote12 Quote Link to comment Share on other sites More sharing options...
karlfer Posted January 30, 2017 Share Posted January 30, 2017 (edited) OK, seeing as there are guys in this thread that really know their stuff, dumbass question. I would love to get two of these 210's. Would that mean I'm running at 6 ohms? Current amp is Ashdown RM 800 (mannnn, that DRIVE!! getcha Lemmy on). Edited January 30, 2017 by karlfer Quote Link to comment Share on other sites More sharing options...
Merton Posted January 30, 2017 Share Posted January 30, 2017 [quote name='karlfer' timestamp='1485772214' post='3226475'] OK, seeing as there are guys in this thread that reall know their stuff, dumbass question. I would love to get two of these 210's. Would that mean I'm running at 6 ohms? Current amp is Ashdown RM 800 (mannnn, that DRIVE!! getcha Lemmy on). [/quote] Correct I can vouch for the RM sounding IMMENSE through the Two10 cab btw. If I had not been in the financial position I find myself that probably would have become my main rig this year. Quote Link to comment Share on other sites More sharing options...
LewisK1975 Posted January 30, 2017 Author Share Posted January 30, 2017 I'd say so Karl - two 12ohm cabs in parallel = 6ohm load presented to the amp. Quote Link to comment Share on other sites More sharing options...
chris_b Posted January 30, 2017 Share Posted January 30, 2017 (edited) Yes, 2 cabs will be 6 ohms. Just above the minimum on most amps. As usual, over-thinking is rampant. The guys who are running at 12 ohms say they are loud enough. . . . which is what Alex said on the website. If 12 ohms is 2/3rd of the volume of an 8 ohm cab then just turn the master volume up 2 clicks and there will be no difference in overall volume. I don't see the point in small 4ohm cabs, IMO the best idea is to leave yourself the option of adding another cab if you want more volume. And anyway. . . . IME one of Alex's 8 ohm cabs (even his 12 ohm cabs) are pretty much the equivalent to other manufacturers 4 ohm cabs. Edited January 30, 2017 by chris_b Quote Link to comment Share on other sites More sharing options...
karlfer Posted January 30, 2017 Share Posted January 30, 2017 Thanks fellas appreciated. Quote Link to comment Share on other sites More sharing options...
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