They will work, but will start to rag out soon. Go to your local thrift store and get a surround sound subwoofer. They usually have a couple for cheap.
A resistor can be added to the 8ohm across the terminals, but I don't know the needed value. 4ohm sounds logical, but not sure if it's correct.
A amps watt rating can be confusing at times because there's a operational wattage for the amp and a output wattage for the amp. Sometimes an amps label will show the operational wattage and people will think it's the output wattage by mistake. Example: My Silvertone 1482 tube amp says on the back label that it's a 117Volt 70Watt amp, but the output wattage is 15Watts.
Here is the page from WGS on the speaker I'm going to use and the measurements are all listed at the bottom of the page. This speaker will handle over 93 decibels. Should be enough.https://wgs4.com/vet10
These speakers rock. I like their British Voiced Green Berets too.
Oh man.... you are the best....this is just what I have been looking for. I've been scouring the net for a schematic that had the pots included in the diagram. Thanks a million for posting this drawing.
I revised the schematic and posted it at the top of the page.
Changes are N3 chips instead of the N1's due to the N1 chip's not lasting long in a bridged amp.
A change in pot/controls: 1 volume - 1 tone - 2 gain.
Added caps in the output lines: the cap values will change depending on the speakers used.
For example: The Ruby and other single chip amps have a 220uf cap in the + output line to the speaker. Since this is a bridged amp, it gets a cap in the + and - lines to the speaker.
I used a WGS 8ohm 20watt 10" speaker for my build and I started off with the 220uf caps, but it was very very bright sounding. Might be what you like, just not what I was going for. So I tried a couple of different value caps til I got the tone I liked which ended up being 10uf for both lines. So the speaker you use(due to it's voicing) or your personal likes will determine which output caps will be best.
My original build had no caps in the output lines, but also had a lot of unwanted noise and some oscillation.
Can you post a pic?