I have an old B&K ST-120 amp with a blown MOSFET (that I hope to fix soon). On the other hand, the amp case, layout, power supply, and interconnects seem perfect for a class D retrofit as well.
PS has toroidal transformer and dual +/- 53V rails, guessing about 100W per side based on original amp rating.
Am thinking of trying IRS2092 boards out, the voltages look compatible - any other ones to consider?
PS has toroidal transformer and dual +/- 53V rails, guessing about 100W per side based on original amp rating.
Am thinking of trying IRS2092 boards out, the voltages look compatible - any other ones to consider?
Likewise, I would go for these:
Assembled LJM L15D-Pro Stero Power Amplifier Board IRS2092 IRFB4019 J163 | eBay
Assuming, of course, that there's room.
I run a pair of these, in a home built pair of monoblocks. They sound as good or better than various (expensive) commercial amps, both valve and solid state I have tried
I especially like the fact that they come with relay switched outputs that provide protection against the risk of speaker damaging failures.
Assembled LJM L15D-Pro Stero Power Amplifier Board IRS2092 IRFB4019 J163 | eBay
Assuming, of course, that there's room.
I run a pair of these, in a home built pair of monoblocks. They sound as good or better than various (expensive) commercial amps, both valve and solid state I have tried
I especially like the fact that they come with relay switched outputs that provide protection against the risk of speaker damaging failures.
Thank you! I like the boards with relay protection and it appears they could fit. The original amp had zero speaker protection for it's outputs (not even a fuse) which likely led to it's demise.
I have DIY'ed TPA3116 amps before, not familiar with IRS2092 yet.
Here's a pic of internals awaiting replacement MOSFETs on left channel.
I have DIY'ed TPA3116 amps before, not familiar with IRS2092 yet.
Here's a pic of internals awaiting replacement MOSFETs on left channel.
Attachments
Looks very 'doable'
The heatsinks will be pretty much redundant but that doesn't matter. I don't know what size the main capacitors are, but it wouldn't hurt to add a couple more.
I did check out a few class A/B amp modules, but most of them are sub +/-50V rails.
I would definitely go for it.
The heatsinks will be pretty much redundant but that doesn't matter. I don't know what size the main capacitors are, but it wouldn't hurt to add a couple more.
I did check out a few class A/B amp modules, but most of them are sub +/-50V rails.
I would definitely go for it.
I'm doing this to an old Sony TAF6B, it's a great idea as you get a great looking box to go with the good sound and a metal box is always a good idea with class D.
Class-D is very reliant on the PSU (90% efficient!) , and usually wants a single rail low(er) voltage for the same power.
So if it was me I'd install a decent switcher, and use the heatsinks for a high gain high frequency transistor as an emitter follower power regulator driven from a stable (independent) voltage reference. Only drop 2-3 V as you shouldn't need more and it helps if you accidentally 'weld' the transistor.
You can buy cheap BTL compatible speaker protectors and also use fuses as belt and braces.
Remember you may need power for lamps and preamp - you can buy nice switchers, DC-DC or use an analog supply for these. Many DC-DC have a built in voltage display and a pot so you can tune them to exactly the required voltage. E.g. my pre-amp needed a -35-0+35 for the pre-amp (op-amp) so I had to use a twin secondary xfmr into two DC-DC regulators and cascade them - earthing the centre - to re-create the supply it needed (which in that amp came from a retro switcher!).
You are left with a huge selection of class-D, I am using a modded 7498 but you may want to try the AA-AB32313 module (400 x 2) as people seem to like it. Give it enough space and you can swap it out in the future as you fancy.
I also found a nice big metal conversion box gives a huge amount in internal space which makes it easy to upgrade to air cores in the future.
Class-D is very reliant on the PSU (90% efficient!) , and usually wants a single rail low(er) voltage for the same power.
So if it was me I'd install a decent switcher, and use the heatsinks for a high gain high frequency transistor as an emitter follower power regulator driven from a stable (independent) voltage reference. Only drop 2-3 V as you shouldn't need more and it helps if you accidentally 'weld' the transistor.
You can buy cheap BTL compatible speaker protectors and also use fuses as belt and braces.
Remember you may need power for lamps and preamp - you can buy nice switchers, DC-DC or use an analog supply for these. Many DC-DC have a built in voltage display and a pot so you can tune them to exactly the required voltage. E.g. my pre-amp needed a -35-0+35 for the pre-amp (op-amp) so I had to use a twin secondary xfmr into two DC-DC regulators and cascade them - earthing the centre - to re-create the supply it needed (which in that amp came from a retro switcher!).
You are left with a huge selection of class-D, I am using a modded 7498 but you may want to try the AA-AB32313 module (400 x 2) as people seem to like it. Give it enough space and you can swap it out in the future as you fancy.
I also found a nice big metal conversion box gives a huge amount in internal space which makes it easy to upgrade to air cores in the future.
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Had not considered using those heatsinks for a power supply mod, interesting. Probably beyond me (yet has me thinking too for higher power). Figure whatever I replace with will not meet rated power on the boards because the original PS is not that beefy.
I would love to see your Sony upgrade - sounds very cool (in terms of both efficiency and repurposing 🙂).
Go for the class D modules. The heatsinks could even be removed for other projects and replaced by metal plates cut from another unused case. Class D draws typically 50% less current from power supply at same power output (typical 3 to 8 music crest factor). IRS2092 boards don't compensate for HF peaking due to speaker impedance but do compensate for any supply sag quite well, so no need to improve PSU. Next level are UCD or similar modules that do compensate for HF peaking.
Class 'D' retrofit
I currently have three of these because I liked the first one so well: 2x100W TPA3116 D2 Dual Channel Digital Audio Amplifier Board 12V-24V For Arduino Sale - Banggood.com The 3116 is a Texas Instruments chip and they actually do achieve rated power. I am currently running one as a subwoofer amp in my primary system. Yesterday, I pushed my system to it's limits and the main amp cut out first! They are, to say the least, very impressive!
I currently have three of these because I liked the first one so well: 2x100W TPA3116 D2 Dual Channel Digital Audio Amplifier Board 12V-24V For Arduino Sale - Banggood.com The 3116 is a Texas Instruments chip and they actually do achieve rated power. I am currently running one as a subwoofer amp in my primary system. Yesterday, I pushed my system to it's limits and the main amp cut out first! They are, to say the least, very impressive!
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