Recommendation for mono boombox?

[lost eden]

As you may have seen in this thread I am building a new boombox this summer with the intention of it being substantially more powerful than the last one I built which used a Sure TA2024 board with 2x 6" car speakers & a 12v 7AH SLA.

The new boombox is going to have a 10" mid/bass & a horn-loaded compression driver for HF. I've already designed the enclosure & bought most of the parts, including 2x 12v 3.4AH SLA & a 24v Mean Well SMPS, I'm just finding somewhere that will cut the wood for the enclosure for me now.

Originally I was going to use a TDA8920BTH board because it was cheap, can run in bridge (the boombox has a single 10" & a single compression driver, so mono) & I thought it would run from 2x 12v SLA in series. I got it yesterday & discovered that it actually needs a symmetric supply (+/-24v, I didn't even know what a symmetric supply was before!) so it's not so useful. I have been looking for ways to still use the amp with the 2x 12v SLA but the options don't seem great;

• I could use something like this or a PT6650 but I suspect that will waste a lot of energy as heat & might not sound great for an audio application.
• I could try using the 2x batteries separately to get +12/0/-12 but with the safety cutoff at 12.5v the amp would probably refuse to work long before the batteries were fully discharged.

I think my best option is to put the TDA8920BTH I bought aside (it only cost ~£20 delivered & I can use it for another project) & look for another amp. Does anybody have any recommendations? Ideal requirements are;

• Runs off +24v DC (2x 12V SLA) outdoors & a +24V 2.5A Mean Well SMPS when indoors.
• Mono, or bridgeable.
• Capable of >50W RMS into an 8ohm load.

I've ruled out the TDA8920 family because of the need for a symmetric supply, likewise the LM3886 & associates.

I know that the TP2050 cannot be bridged because it is internally bridged (or something like that), but can be paralleled? I don't really understand what paralleling means, so can anybody tell me if the TP2050 (or similar) would be of any use?

A different & rather inelegant solution I thought of would be to use something like the 2x 100W TC2000/TP2050 board from Sure & use 1 channel for the mid/bass & the other channel with substantial attenuation for the HF. Seems like a dreadful hack though...

[fraction]

This? Hifimediy T1 CTR TK2050 2*80W STA508 tripath amplifier | eBay UK

[lost eden]

Originally Posted by fraction

This? Hifimediy T1 CTR TK2050 2*80W STA508 tripath amplifier | eBay UK

I've looked at that, but it "can not be easily bridged" so I would only be making use of one channel & wasting the other. The 80W into 8ohm is at 35v & 10% THD so with my 24v (maybe more like 27v to begin with) I would probably be limited to under 50W particularly if I want it to sound half decent.

The Hifimediy T3's power requirements are too much for a portable rig, I'd have the same problems as with the TDA8920BTH.

If there were an easily bridgeable STA508 board available that might be perfect, but I haven't come across one yet?

Edit: There is this one but I'm going to contact him about the price; he has two auctions, the first for a single amp & the other for 2x amps but they're almost exactly the same price...

Edit 2: Ah, one is the first version & the other is the second version. Wonder what makes the second version so much more expensive...

[lost eden]

How easy is it to use a stereo amp to bi-amp the mid/bass & the tweeter? I presume I'll have to build a line-level crossover to split the input going into the amp & maybe attenuate the high frequency input? It's beginning to look as though something like that stereo STA508 might be the cheapest & easiest solution as long as I can use it in a bi-amp configuration.

[kristleifur]

Originally Posted by lost eden

If there were an easily bridgeable STA508 board available that might be perfect, but I haven't come across one yet?

IIRC, all TK2050-based amps are internally bridged to begin with - that's the reason.

[lost eden]

Originally Posted by kristleifur

IIRC, all TK2050-based amps are internally bridged to begin with - that's the reason.

The TK2050 cannot be bridged, but I was talking about the STA508 which can. The only bridged STA508 amps I've come across are those from arjenhelder_electronic, I was wondering why there aren't more?

[kristleifur]

Originally Posted by lost eden

The TK2050 cannot be bridged, but I was talking about the STA508 which can. The only bridged STA508 amps I've come across are those from arjenhelder_electronic, I was wondering why there aren't more?

As far as I know, the STA508 is just the same. Virtually all TK2050-based amps are already bridged - it's how you get useful power out of the chip. And by TK2050-based, I mean using the power chips TP2050, STA505 to STA517B, or Apogee DDX2000 etc.