Currently there was a talk and an attempt in our local audio community to build an amp which will utilize two bridged amp to be connected again in bridge mode. Since the debate is not yet close, I would like to ask your expert opinion whether it is possible or not, or any of you has done this, or is true that Crown or any manufacturer made the bridged-bridged amp and already sold this in the market?
Crown’s old bridged-bridged amps do not have a ground reference for the first “bridge”. The two bridgeable channels are independent and floating. This is the only way it can be made to work. Do not even try it with conventional amplifiers.
It is possible to clone. You do need completely independent power supplies for each channel, and follow the grounding scheme to the letter. You are fortunate that these amps are old and obsolete so the schematics are still available. Can’t get any documentation on any model since the Harmon takeover.
It is possible to clone. You do need completely independent power supplies for each channel, and follow the grounding scheme to the letter. You are fortunate that these amps are old and obsolete so the schematics are still available. Can’t get any documentation on any model since the Harmon takeover.
Thank you so much. This information is very useful indeed. I haven't found any schematic yet on Crown's bridged-bridged amp. I hope it is not hard to find one. 👍🙂
You want the original Crown MacroTech line. They have been posted on this site before and may still be around on the Crown website. There was a white paper biaically how it works, which may still be there. The “VZ” versions have additional circuitry which is not needed to basic function.
Somewhere there is a thread on here about building a “grounded bridge” amp using only 2N3055 or other cheap low voltage output transistors. I’m not sure it was ever constructed, but the general principles were sound.
Somewhere there is a thread on here about building a “grounded bridge” amp using only 2N3055 or other cheap low voltage output transistors. I’m not sure it was ever constructed, but the general principles were sound.
*Maybe* it would be more straight forward to simply build an amp with desired power from the beginning instead of tryin to bridge bridge smaller ones.
What kind of final power is your golal?
As a side note, very high power amps by definition dissipate a lot of heat.
"Normal" amps, or at most simple bridged ones, can be fed from the same supply.
If you use Class H to reduce dissipation, supply is still relatively simple and can feed both channels even if bridged.
Now if you need multiple independent power supplies, the task becomes more complex than it´s worth.
Just a "thinking aloud" comment.
What kind of final power is your golal?
As a side note, very high power amps by definition dissipate a lot of heat.
"Normal" amps, or at most simple bridged ones, can be fed from the same supply.
If you use Class H to reduce dissipation, supply is still relatively simple and can feed both channels even if bridged.
Now if you need multiple independent power supplies, the task becomes more complex than it´s worth.
Just a "thinking aloud" comment.
Thanks again, luckily I found Electrovoice EV P3000 Service manual. I think this will suffice my curiosity about the bridge-bridge configuration. The circuit is quite complex with different supplies for front-end stage and power amp stage. For front-end, it uses dual supply, while the power stage is a single supply grounded bridge stage. The upper amp output drives the load, while the lower amp output is connected to ground.
I have designed class AB amp with +/-230V rails. Because it is uses high voltage rails, the topic pops up in our radar, to seek the same higher power output using bridge-bridge topology with lower rails.
I have designed class AB amp with +/-230V rails. Because it is uses high voltage rails, the topic pops up in our radar, to seek the same higher power output using bridge-bridge topology with lower rails.
It is always more straightforward to just build a regular amp at the desired power/voltage level. Depending on that level, the voltage can go from the ridiculous to the sublime. I’m not afraid to build a tube amp running of 600-700 volts, or a solid state one running off 300. Some people are, perhaps for good reason.
It may also be a matter of resources. Often a less straightforward approach makes a project possible if you can use what you have, or obtain for a song, as opposed to paying full price for. Back in the day when all I could resonantly obtain were 80 volt transistors and low voltage transformers and caps I did all sorts of “stupid” things to make 200+ watt per channel amps. They wouldn’t have happened any other way. Perhaps the original idea was to use only 24 or 48 volt SMPS bricks, which are cheap and plentiful.
It is also “fun” to play with old technology.
It may also be a matter of resources. Often a less straightforward approach makes a project possible if you can use what you have, or obtain for a song, as opposed to paying full price for. Back in the day when all I could resonantly obtain were 80 volt transistors and low voltage transformers and caps I did all sorts of “stupid” things to make 200+ watt per channel amps. They wouldn’t have happened any other way. Perhaps the original idea was to use only 24 or 48 volt SMPS bricks, which are cheap and plentiful.
It is also “fun” to play with old technology.
That.
And if devices can´t take the voltage (not a problem these days), you can put them in series , has been done many times with success, a popular solution in the 70´s.
And topology, specially PSU topology, remains simple and straightforward.
The channel bridge in the two channel mode is nothing more then a trick to raise the supply rails of the 'hot' amplifier by the 'cold' amplifier. The bridged mode is connecting these channels with one with inverted phase.
One could use these two (unbridged) amps as another hot and cold amp to lift another supply even further, and bridged two of those setups for massive output power.
But as said, that's the old analog fashion, and complex and vulnerable for mishap.
But as an old analog bloke, I'd rather would opt for a bridged pwm mosfet amp, directly driven from the rectified wall outlet, 230Vac (stronghand countries) or 110Vac (weakhand countries). With several losses, the stronghand yields approx (200Vac)exp2 / 8Ω = 5kW and the weakhands only (100Vac)exp2 / 8Ω = 1.25kW.
seanny of #9 is right: he needs as many as he likes transformers to level stronghands.
#;-p
One could use these two (unbridged) amps as another hot and cold amp to lift another supply even further, and bridged two of those setups for massive output power.
But as said, that's the old analog fashion, and complex and vulnerable for mishap.
But as an old analog bloke, I'd rather would opt for a bridged pwm mosfet amp, directly driven from the rectified wall outlet, 230Vac (stronghand countries) or 110Vac (weakhand countries). With several losses, the stronghand yields approx (200Vac)exp2 / 8Ω = 5kW and the weakhands only (100Vac)exp2 / 8Ω = 1.25kW.
seanny of #9 is right: he needs as many as he likes transformers to level stronghands.
#;-p
MB, you're right it's a trick of the old when Vceo specs of those trannies were still low. Fast forward, nowadays, power trannies for audio amplification have already reach 350v like the MJL4281/4302. With cascoding, still Vceo can be raised twice. Now if cascoding is still not enough, we can employ bridging then. 🙂
Crown published an article at Audio Magazine in the 80's to 90's can't remember the month...they were the first ones to come up with such an idea of bridging bridged amps...
and on another note, Mark Levinson used their power amp to do welding job....how neat can that be..
and on another note, Mark Levinson used their power amp to do welding job....how neat can that be..