I would like to refurbish four subwoofers. Each was previously were outfitted with a class-AB plate amp, which unfortunately is terrible. I powered the plate amps from a 300VA transformer that has dual 45Vac secondaries, which translates to an unloaded DC secondary of about 63V, and I would like to re-use them (there is one in each subwoofer box). I would like to remove the remaining amp guts, re-build the power supply, retain that large heat sink from the old AB amp and mount the new amp module to it. I have lots of 100V can style caps that I can use to make a beefy linear power supply. I'm just looking for an amp module to work at this rail voltage. I would prefer not to add other DC driver voltages if possible, although I would consider that. The drivers will be 4R nominal 12" subwoofers.
I would like to keep the cost at or below $200 per amp module and am looking for at least 250W@4R. Perhaps there is an older ICEpower or UCD module (e.g. UCD400) that would be good when only used for subwoofer duty?
Other suggestions welcome!
I would like to keep the cost at or below $200 per amp module and am looking for at least 250W@4R. Perhaps there is an older ICEpower or UCD module (e.g. UCD400) that would be good when only used for subwoofer duty?
Other suggestions welcome!
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Hmmm, the more I look at the Hypex UCD400HG the more I think THAT would be perfect for this project!
Now, if I could only buy them from a US source... I can only find it available in Europe (DIYClassD, AudioPhonics, etc.).
Now, if I could only buy them from a US source... I can only find it available in Europe (DIYClassD, AudioPhonics, etc.).
I thought about refitting an old class AB amp with a class D board using the original transformer.
Decided it was more economical to use a discarded laptop brick to power it.
Look for a mono class D amplifier board e.g.:
https://www.ebay.co.uk/itm/38526712...Pio1mIgFq8Ermg/opZxPeM2Owb|tkp:Bk9SR8Cyp7jCYQ
Note your sub will still need the low pass filtering arrangements as fitted to the original plate to adjust levels to match your system, unless you are implementing a line level crossover system or DSP.
Decided it was more economical to use a discarded laptop brick to power it.
Look for a mono class D amplifier board e.g.:
https://www.ebay.co.uk/itm/38526712...Pio1mIgFq8Ermg/opZxPeM2Owb|tkp:Bk9SR8Cyp7jCYQ
Note your sub will still need the low pass filtering arrangements as fitted to the original plate to adjust levels to match your system, unless you are implementing a line level crossover system or DSP.
@russc Thanks for your thoughts. To clarify a little, the transformer is off-board, in fact it is bolted to the bottom of the subwoofer cabinet and not part of the plate amp. I have the caps and rectifier that I would need to create the linear PS, so no cost there. The plate amp was full range and I use exclusively DSP in all my projects, so no need for any line level circuitry, etc. Thanks for the link but the TDA7498E doesn't' reach the stated 220W until 10% distortion, into 3R only, and needs a 36Vdc power supply to get there. That's hardly laptop brick territory (those are typically 19V). According to the datasheet, at 19V you get less than 60W in BTL mode at 1% distortion, and only 75W at 10% distortion. That's woefully underwhelming, as I have come to expect from that sort of chip amp.
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Here's one. It can use a power supply up to +/- 70volts dc. 250 watts 8 ohms, works down to 2 ohms if I read it right.
https://www.ebay.ca/itm/Assembled-H...e-a672-40f3-97ff-fd8a22efea00&redirect=mobile
https://www.ebay.ca/itm/Assembled-H...e-a672-40f3-97ff-fd8a22efea00&redirect=mobile
@multisync Hmmm, looks a bit sketchy. I was not aware that sort of configuration was available for the IRS2092 at that power and into 2R. Do you happen to have one and can relate your experience with it?
The Hypex UcD400HG is more expensive but it is from a known entity that sells high quality amp modules, and I can attach it to the existing heat sink of the plate amp after I remove the old board.
The other option I was considering is the IcePower 500A, but it needs an additional supply of +/-15Vdc. I could probably toss that together from parts I have around. For the added complexity its about the same price as the Hypex UCD400HG but I can get the IcePower 500A locally.
The Hypex UcD400HG is more expensive but it is from a known entity that sells high quality amp modules, and I can attach it to the existing heat sink of the plate amp after I remove the old board.
The other option I was considering is the IcePower 500A, but it needs an additional supply of +/-15Vdc. I could probably toss that together from parts I have around. For the added complexity its about the same price as the Hypex UCD400HG but I can get the IcePower 500A locally.
Hypex or Purifi both use 63V rails i believe. I don't know where to get them state side though. I've purchased directly from Purifi and Hypex. Shipments from both companies went fine, no problems.
I beleive the ICEPower 500A unit needs 0-75vdc, single rail, not dual rail... in addition to the +/-12vdc.
You can probably get away with just the single 0-65vdc connection (min is 0-42vdc) to the 500A on your linear power supply, but wont get anywhere near the output power...
You can probably get away with just the single 0-65vdc connection (min is 0-42vdc) to the 500A on your linear power supply, but wont get anywhere near the output power...
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You could maybe get away with the ICEPower 1000A tho (it only goes to 3khz anyway - perfect for subwoofer duty)... max is 0-125vdc, and you would be at 0-126vdc with your 63-0-63.... but you only have 300VA....
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I've been using a pair of these for occasional use over the last 3 or 4 years at +/- 67.5 V rails. Not as fancy as some, but they seem to do the job. Rock bottom price too.
https://www.ebay.com.au/itm/3551609...q6+e3zCsA20XLagj4fsgU6OnBP|tkp:Bk9SR_qOhYX3Yg
https://www.ebay.com.au/itm/3551609...q6+e3zCsA20XLagj4fsgU6OnBP|tkp:Bk9SR_qOhYX3Yg
@Nisbeth Agree, but with his 300va 45-0-45 tranny, the 500A could only be run at 0-65vdc, while the 1000A could be run at 0-126vdc, correct?
Whoops, hold on, I see your point, but are the following statement both correct as the OPs tranny only has 300VA (and limiting factor)?
there is no difference in output power between the ICE500A and ICE1000A if you run them on the same supply voltage.
there is no difference in output power between the ICE500A and ICE1000A if you run them on the same supply.
Whoops, hold on, I see your point, but are the following statement both correct as the OPs tranny only has 300VA (and limiting factor)?
there is no difference in output power between the ICE500A and ICE1000A if you run them on the same supply voltage.
there is no difference in output power between the ICE500A and ICE1000A if you run them on the same supply.
I don't know if @CharlieLaub found a solution yet or not, but UcD250LP modules can be found pretty cheaply on the second hand market. Fits the criteria for both power and supply voltage.
I recently purchased a used Sonance DSP 8-130 for $100 that contains 8x UcD250LP modules. Quite the bargain.
I recently purchased a used Sonance DSP 8-130 for $100 that contains 8x UcD250LP modules. Quite the bargain.
Anon - Yup, I have bought up those Sonance units too...but the UCD250LP does need that input buffer...donno if it matters for subwoofer duty...
Yes, IMO they are both correct.
A 300VA transformer should not be the limiting factor with a 500W amp that is only used for music, especially if it is a linear supply without a hard current limit. 126VDC would be very high for a 1000A because there is no additional margin for line voltage fluctuations etc. so that sounds unsafe for me.
The old eval-kits for the ICEpower A-series used a 400VA transfomer for the 500A kit. However, that rating included the low-voltage supply (app. 20-30VA) and the same transformer was used for both the mono and stereo kits.
The 1000A eval. kit used a 550VA transformer for the mono board, again low-voltage supply included.
I used these upcycle a Fisher power amp with butchered original boards. Works well, fan a little noisy. I've been running them 2 summers in my outside system.