dylan722 Posted January 20 Posted January 20 After years of service my Legend acoustics Kurlo subwoofer has stopped working. I have tested the driver and the amp output which are both working. I would like to try and replace the amp to keep the unit going. Unfortunately I don't know what part of the amp is faulty (and in the opinion of a local repairer it probably isn't economical to repair) It has a 450w plate amp which is 265mm square. I note that subsequent versions of this sub used a 300w BASH plate amp. It seems that I can either replace the plate amp (+/- extra to make it fit correctly) or use a plate amp run externally or use an external amp. Dayton seem to be the main option here in Aus as far as I can see: https://www.daytonaudio.com/product/1851/spa300-d-300-watt-class-d-subwoofer-plate-amplifier There is a 300w model is class and ~$360 https://www.daytonaudio.com/product/1092/spa250-250w-subwoofer-plate-amplifier A 250w AB unit is ~$530 https://www.daytonaudio.com/product/1030/spa500-500w-subwoofer-plate-amplifier the 500w unit is ~$750 The 300w unit seems to have the best price to wattage, but am I missing something? seeing the 250 AB being significantly more than the 300D seems a bit of a worry I've seen people commonly use the inuke and crown amps in the DIY setting. The former seems to be good value compared with the Daytons options listed above. What is the downside? Open to all suggestions and experiences Thanks!
Keith_W Posted January 20 Posted January 20 Why don't you get in contact with them? https://www.legendspeakers.com.au/ Contact details at the bottom of the webpage. I believe Dr. Crawford is still around.
dylan722 Posted January 20 Author Posted January 20 Thanks - that was my first port of call. They have been out of production for 10years and he doesn't have any replacement amps unfortunately.
Cloth Ears Posted January 21 Posted January 21 On 20/01/2025 at 9:46 PM, dylan722 said: Thanks - that was my first port of call. They have been out of production for 10years and he doesn't have any replacement amps unfortunately. Expand You could try Redgum (https://www.redgumaudio.com/product/rgsw3-amplifier-plate/). It wouldn't need any extra hole sizing, but you'd need to mount it to a separate board and then attach that over the hole in your subby.
almikel Posted January 21 Posted January 21 (edited) On 21/01/2025 at 12:58 AM, Cloth Ears said: You could try Redgum (https://www.redgumaudio.com/product/rgsw3-amplifier-plate/). It wouldn't need any extra hole sizing, but you'd need to mount it to a separate board and then attach that over the hole in your subby. Expand In another thread I saw Redgum will cease manufacture 1 Jan 25 This may dissuade the OP from installing a Redgum amp as future support may be problematic? On 20/01/2025 at 10:26 AM, dylan722 said: The 300w unit seems to have the best price to wattage, but am I missing something? seeing the 250 AB being significantly more than the 300D seems a bit of a worry Expand I'd be entirely comfortable using a class D amp for sub duties. The class D doesn't need anywhere near the heatsinking of class AB, so that will lead to smaller heatsinks/smaller case/lighter/lower shipping costs etc - there's commercial justification for class D amps being less expensive than class A/B amps. On 20/01/2025 at 10:26 AM, dylan722 said: It has a 450w plate amp which is 265mm square. I note that subsequent versions of this sub used a 300w BASH plate amp. Expand Deciding if you should stay with a similarly powered amp (450W) or replace it with a 300W amp is very hard to determine - generally I would like to maintain the headroom of the original amp. Unless you have some way of determining that your sub never hit peaks above 300W, I would be cautious of reducing amp power. It could be entirely fine, and your 450W amp never went above say 200W on peaks, and 300W is sufficient! On 20/01/2025 at 10:26 AM, dylan722 said: I've seen people commonly use the inuke and crown amps in the DIY setting. The former seems to be good value compared with the Daytons options listed above. What is the downside? Expand The downside is the Dayton plate amps will have some DSP/EQ features. Heading down the path of inuke and crown power amps is fine also, but they don't have EQ - good bang for buck for $ vs watts...but you should factor in the cost of an additional unit to manage EQ/DSP, like a miniDSP 2x4 HD. Arguably a better approach, if you use the miniDSP to implement a proper crossover between main speakers and sub, including setting time alignment between mains and sub (which may require delaying your main speakers). cheers, Mike Edited January 21 by almikel clarification 2
dylan722 Posted January 21 Author Posted January 21 Thank you everyone for your replies I was considering the redgum but then found out the above - as you suspected Mike I was put off! As it turns out the 450w was the max power consumption rating of the amp - so I presume it is actually a 300-350w RMS unit (apparently it was a modified jaycar AA0501?). I think I'll go with the 300w digital unit as the price seems reasonable - hopefully I'll get a bit more life out of the sub. I'll report back once it is installed. Regards Dylan 1
pete_mac Posted January 21 Posted January 21 On 21/01/2025 at 7:08 AM, almikel said: I'd be entirely comfortable using a class D amp for sub duties. The class D doesn't need anywhere near the heatsinking of class AB, so that will lead to smaller heatsinks/smaller case/lighter/lower shipping costs etc - there's commercial justification for class D amps being less expensive than class A/B amps. Expand Indeed, there is nothing to be worried about here. One factor worth considering with both Class AB and Class D subwoofer amps is in my personal experience, many subwoofer amps die prematurely when left in the auto power up / standby mode for extended periods. I've repaired a few in my time. Some need capacitor replacements only, but others suffer catastrophic failures and are essentially bin-jobs. I get the convenience factor, but where possible I would suggest manually switching subwoofers on and off to extend the lifespan of the plate amps. 1
Upgrayed Posted January 25 Posted January 25 I have been using Hypex Fusion plate amps. Not expensive, have infinite DSP options and so far reliable
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