ltank Posted July 6, 2023 Share Posted July 6, 2023 (edited) Hello wizards, As an absolute beginner to cabinet repair and musical equipment maintenance, I'm venturing into uncharted waters here, so please bear with me. I need advice on removing glued speakers and on identifying suitable replacement speakers. I am the proud owner of an exceptional Mesa Boogie PH410, which I believe is top-notch. However, following our recent performance, I suspect that one of the four speakers has blown. It's begun to sound noticeably distorted compared to the others, and it also seems to vibrate more intensively. I purchased it second-hand, and the previous owner had one of the speakers replaced by a professional repair technician who has experience with this specific model. However, he is currently unable to service it within an acceptable timeline, hence he suggested that I simply purchase the same type of speaker he had installed earlier. When I tried removing the faulty speaker, I found it firmly glued in place. Can anyone suggest a reliable method to handle this? I own a heat gun; would that be an appropriate tool to use in this situation? To assist with identifying the right replacement, I've attached a photo of the speaker that was recently replaced. To my limited understanding, the speaker indicates 4ohms. But if the total cabinet impedance is 8ohms, shouldn't each speaker, when wired in parallel, be 32ohms? Interestingly, on the Mesa Boogie's official website, it's mentioned that the original PH custom Eminence speakers are no longer in production. They recommend using Eminence Legend CA10 as a suitable replacement. However, I am unsure of the impedance I should opt for. Can anyone provide guidance on this? https://store.mesaboogie.com/products/speaker-10-eminence-legend-ca10-8-200-watt-8-ohm-1.html The original speakers don't have any discernible markings on them. I sincerely hope some of you can provide me with some guidance. My apologies for the lengthy narrative, but I am genuinely in need of assistance. Thank you. Edited July 6, 2023 by ltank Quote Link to comment Share on other sites More sharing options...
Mottlefeeder Posted July 6, 2023 Share Posted July 6, 2023 A cab with ports will perform better if it is not also leaking air from the joints, so what you may have is a sealant around the speaker, or just a speaker chassis that is a tight fit in the rebated cavity. It is unlikely to be glued in place because in addition to the eight screws, it would serve no useful purpose and would make servicing more difficult. Your repair tech may be able to confirm that. If you have confirmed that it is faulty, you have nothing to lose by taking the screws out and hitting the rear of the chassis (or the magnet) with a mallet to break the seal. David 1 Quote Link to comment Share on other sites More sharing options...
BigRedX Posted July 7, 2023 Share Posted July 7, 2023 Is it the replacement speaker that has blown? For the cab to have an overall impedance of 8Ω the speakers should all be 8Ω each and wired in series/parallel pairs. If this replacement speaker really is 4Ω then the impedance of the whole cab will be under 8Ω (6.86Ω approx) which could also damage you amp if it isn't rated for loads under 8Ω, or it's valve amp and you are using the wrong transferee tap output. Also what is that bit of orange tape doing on the white wire? Is it just for identification purposes or is it covering a join? If it's a join I'd be looking at that as a possible source of any unwanted noises, and replacing it with single continuous wire. Quote Link to comment Share on other sites More sharing options...
Hellzero Posted July 7, 2023 Share Posted July 7, 2023 Do you have a multimeter @ltank? When yes, unconnect an official "Mesa Boogie" speaker and measure it, then give us the resistance reading. You won't have the exact impedance of the speaker (which is a way more complicated process), but you could know it by this reading. If it's an 8 Ohms cabinet, why the heck is there one 4 Ohms speaker in it? Are you sure it's an 8 Ohms cabinet? Quote Link to comment Share on other sites More sharing options...
warwickhunt Posted July 7, 2023 Share Posted July 7, 2023 A professional repair technician put a 4 ohm driver in a cab rated at 8 ohms and populated by all 8 ohm drivers... you've had a lucky escape that he is busy! If you have a valve amp you really need to get the ohmage sorted. If you have a solid state amp it is less of an immediate issue as your amp is likely to go down to 4 ohms but it is not good for the drivers to be mismatched like that. 3 Quote Link to comment Share on other sites More sharing options...
John Cribbin Posted July 7, 2023 Share Posted July 7, 2023 You need agedhorse who is one of the guru's at Mesa Boogie and is very active helping with MB issues. I don't know if he is still active here, but I'm probably breaking a forum rule by suggesting if he doesn't pick up here, post the issue on Talkbass were he's certainly active. Good luck with getting your issue resolved. 1 Quote Link to comment Share on other sites More sharing options...
warwickhunt Posted July 7, 2023 Share Posted July 7, 2023 I'm sure @agedhorse will be along shortly, he's on the ball with stuff. 1 Quote Link to comment Share on other sites More sharing options...
Dan Dare Posted July 7, 2023 Share Posted July 7, 2023 6 hours ago, warwickhunt said: A professional repair technician put a 4 ohm driver in a cab rated at 8 ohms and populated by all 8 ohm drivers... you've had a lucky escape that he is busy! Yep. Probably explains why it went pop. It's been copping most of the output of the amp. 1 Quote Link to comment Share on other sites More sharing options...
ltank Posted July 7, 2023 Author Share Posted July 7, 2023 I'm truly appreciative of your prompt responses! Currently, the cabinet isn't at my place, it's situated at our studio. But I'll swing by, give some of your ideas a try, and gather some more info so I can answer your questions better. 13 hours ago, BigRedX said: Is it the replacement speaker that has blown? For the cab to have an overall impedance of 8Ω the speakers should all be 8Ω each and wired in series/parallel pairs. If this replacement speaker really is 4Ω then the impedance of the whole cab will be under 8Ω (6.86Ω approx) which could also damage you amp if it isn't rated for loads under 8Ω, or it's valve amp and you are using the wrong transferee tap output. Also what is that bit of orange tape doing on the white wire? Is it just for identification purposes or is it covering a join? If it's a join I'd be looking at that as a possible source of any unwanted noises, and replacing it with single continuous wire. The original speaker placed above the new one has given out. I'm not sure what the tape is doing there, but I'll get back to you on that one. 13 hours ago, Hellzero said: Do you have a multimeter @ltank? When yes, unconnect an official "Mesa Boogie" speaker and measure it, then give us the resistance reading. You won't have the exact impedance of the speaker (which is a way more complicated process), but you could know it by this reading. If it's an 8 Ohms cabinet, why the heck is there one 4 Ohms speaker in it? Are you sure it's an 8 Ohms cabinet? That's a good point, I wish I had thought of it earlier. I currently don't own a multimeter, but I will acquire one soon and then share the findings with you here. 13 hours ago, warwickhunt said: A professional repair technician put a 4 ohm driver in a cab rated at 8 ohms and populated by all 8 ohm drivers... you've had a lucky escape that he is busy! If you have a valve amp you really need to get the ohmage sorted. If you have a solid state amp it is less of an immediate issue as your amp is likely to go down to 4 ohms but it is not good for the drivers to be mismatched like that. Fortunately I use a GK1001RB which is solid state and can take 4 and 8 ohms. Quote Link to comment Share on other sites More sharing options...
ltank Posted July 7, 2023 Author Share Posted July 7, 2023 In the meantime, if I were to switch out the two speakers (the broken one and the one that the technician incorrectly installed), what would then be the correct ohm to buy? I live in Northern Europe, so I don't have access to US markets. Quote Link to comment Share on other sites More sharing options...
Hellzero Posted July 7, 2023 Share Posted July 7, 2023 8 ohms, if it's an 8 Ohms cabinet. Quote Link to comment Share on other sites More sharing options...
ltank Posted July 7, 2023 Author Share Posted July 7, 2023 21 minutes ago, Hellzero said: 8 ohms, if it's an 8 Ohms cabinet. Regarding wattage, is it essential to stick to 150 watts per speaker, or is there some flexibility? Quote Link to comment Share on other sites More sharing options...
warwickhunt Posted July 7, 2023 Share Posted July 7, 2023 1 hour ago, ltank said: Regarding wattage, is it essential to stick to 150 watts per speaker, or is there some flexibility? TBH there's a lot of variables and unless you know the exact spec of your other speakers (not just 8 ohm 200w or whatever figure), you run the risk of having an unpredictable outcome. You can of course just bung any 8 ohm 10" driver and crossing your fingers but I'd be messaging MB or their distributor; someone on here might know the spec or you may find someone selling identical drivers! Quote Link to comment Share on other sites More sharing options...
Hellzero Posted July 8, 2023 Share Posted July 8, 2023 I would buy 4 Eminence CA10-8 200 Watts as they are the replacement suggested by Mesa Boogie and change the 4 of them, but that's a lot of money... Quote Link to comment Share on other sites More sharing options...
Hellzero Posted July 8, 2023 Share Posted July 8, 2023 By the way, where do you live as Northern Europe is quite vague... Quote Link to comment Share on other sites More sharing options...
ltank Posted July 8, 2023 Author Share Posted July 8, 2023 5 hours ago, Hellzero said: By the way, where do you live as Northern Europe is quite vague... Sorry, Denmark. Quote Link to comment Share on other sites More sharing options...
ltank Posted July 8, 2023 Author Share Posted July 8, 2023 5 hours ago, Hellzero said: I would buy 4 Eminence CA10-8 200 Watts as they are the replacement suggested by Mesa Boogie and change the 4 of them, but that's a lot of money... Why change all four? The two speakers on the right side are fine to my knowledge. Quote Link to comment Share on other sites More sharing options...
Hellzero Posted July 8, 2023 Share Posted July 8, 2023 1 hour ago, ltank said: Why change all four? The two speakers on the right side are fine to my knowledge. Because you won't have the exact same speakers as Mesa Boogie is not providing the original models anymore, so there might be some mismatching in tone... Quote Link to comment Share on other sites More sharing options...
agedhorse Posted July 11, 2023 Share Posted July 11, 2023 On 07/07/2023 at 13:52, ltank said: I'm truly appreciative of your prompt responses! Currently, the cabinet isn't at my place, it's situated at our studio. But I'll swing by, give some of your ideas a try, and gather some more info so I can answer your questions better. The original speaker placed above the new one has given out. I'm not sure what the tape is doing there, but I'll get back to you on that one. That's a good point, I wish I had thought of it earlier. I currently don't own a multimeter, but I will acquire one soon and then share the findings with you here. Fortunately I use a GK1001RB which is solid state and can take 4 and 8 ohms. Sorry, I wasn’t feeling well for a couple of days and missed this. First, a professional service technician that made that kind of mistake (substituting a 4 ohm driver for an 8 ohm driver in a 410 needs to hand in any credentials he may (or may not) have. That’s a bone-head error in judgement, just like choosing a BP-102 which is about the worst driver I can think of for that application. The original vendor for the earlier PH cabinets went out of business, the parts for those drivers are no longer available. The closest match to the drivers in your cabinet is the Legend CA-10 (8 ohm), and the drivers are wired series-parallel. Note that wiring so the polarities are correct is essential. If you need a diagram, message me and I will get it for you. This is why I always recommend verifying that the cabinet you are buying used is really what you think it is, I see folks get burned all the time. 3 1 Quote Link to comment Share on other sites More sharing options...
ltank Posted July 11, 2023 Author Share Posted July 11, 2023 7 hours ago, agedhorse said: Sorry, I wasn’t feeling well for a couple of days and missed this. First, a professional service technician that made that kind of mistake (substituting a 4 ohm driver for an 8 ohm driver in a 410 needs to hand in any credentials he may (or may not) have. That’s a bone-head error in judgement, just like choosing a BP-102 which is about the worst driver I can think of for that application. The original vendor for the earlier PH cabinets went out of business, the parts for those drivers are no longer available. The closest match to the drivers in your cabinet is the Legend CA-10 (8 ohm), and the drivers are wired series-parallel. Note that wiring so the polarities are correct is essential. If you need a diagram, message me and I will get it for you. This is why I always recommend verifying that the cabinet you are buying used is really what you think it is, I see folks get burned all the time. Pm send! Quote Link to comment Share on other sites More sharing options...
Downunderwonder Posted July 11, 2023 Share Posted July 11, 2023 On 09/07/2023 at 03:24, Hellzero said: Because you won't have the exact same speakers as Mesa Boogie is not providing the original models anymore, so there might be some mismatching in tone... There's that, and then the chances of the other two going out on you must be pretty bad. You might get a good enough deal buying four and only be up for one lot of shipping. Could be worth it. Quote Link to comment Share on other sites More sharing options...
agedhorse Posted July 12, 2023 Share Posted July 12, 2023 46 minutes ago, Downunderwonder said: There's that, and then the chances of the other two going out on you must be pretty bad. You might get a good enough deal buying four and only be up for one lot of shipping. Could be worth it. At this point, we don't know if any of the speakers are damaged yet. We do know that one is (very) incorrect. Quote Link to comment Share on other sites More sharing options...
Downunderwonder Posted July 12, 2023 Share Posted July 12, 2023 46 minutes ago, agedhorse said: At this point, we don't know if any of the speakers are damaged yet. We do know that one is (very) incorrect. OP reckoned one of the originals had nasty noises, and some numbnut has put adhesive/sealant on it. Not toast? Quote Link to comment Share on other sites More sharing options...
agedhorse Posted July 14, 2023 Share Posted July 14, 2023 On 11/07/2023 at 18:13, Downunderwonder said: OP reckoned one of the originals had nasty noises, and some numbnut has put adhesive/sealant on it. Not toast? Maybe not, no way to know without a little more troubleshooting. The good news is that we do still have the newest PH 10" driver (8 ohms) in stock. Quote Link to comment Share on other sites More sharing options...
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