The basic amp core in post 118 is one I've used since the mid 80's in amps from 50W to 1500W. The version that's in development now is a class H, and thus needs the rail switches. The power supplies (LV, MV, HV) are roughly 47V apiece giving a total of 280V. The outputs run off only +/-47V until more is needed. They automatically switch the output transistors Vcc to the next tier when the speaker output voltage gets to within 12V of the rail. You could run the amp off off the full supply without the switches, but you'd need more than the 9 outputs per bank and you would want to run the banks in series/parallel (cascode). And it would run blazing hot, trip breakers, and melt wiring. The cascode is easier to build because the power supply is simple and you don't use the rail switches which are sensitive to layout. The cascode version (posted elsewhere) which used only a single +/-127V supply is low-bias class AB. There is NO efficiency advantage of a cascode over a standard output stage. Although the outputs can handle it easily at lower VCE, it still generates a lot of heat. And draws a lot of AC - a single channel monoblock running subs at 2 ohms will melt the plug off the extension cord if you play it loud for 6 hours at a time. Yup, I turned a pair of $40 (at the time) 12/3's into goo. I'm surprised we didn't start a fire. Which is why the next batch is class H. The class H won't be as hard on the electrical supply (or the electric bill) even with higher rails and greater power.
I have also used the same amplifier "core" with just a standard output stage to build a number of lower-power units - including a couple "Dirty Harry"/CS-800 size amps, a few DC300A "clones", "Rebuilt" an old Bose 1801 and a Dyna 400 with all new innards, and two really nice 100W/ch versions.
I have also used the same amplifier "core" with just a standard output stage to build a number of lower-power units - including a couple "Dirty Harry"/CS-800 size amps, a few DC300A "clones", "Rebuilt" an old Bose 1801 and a Dyna 400 with all new innards, and two really nice 100W/ch versions.
wg_ski said:
Wouldn't that be the same for all high power amps ( besides class D )
since the current draw would be the same at high output as there will be large draw on the transformer/toroid *** power output increases so does power consumption, the only gain i see of "hybrid" amps is the power consumtion at low to moderate levels.
The efficiency of class G/H amps is almost double that of a class B amp of same power playing music at the clipping point so it does make a big difference.
Class B amp efficiency is typically about 20% with music at clipping point or up to 50% if heavily compressed (almost no dynamics left at all).
Class B amp efficiency is typically about 20% with music at clipping point or up to 50% if heavily compressed (almost no dynamics left at all).
So these amps switch the rails for every wave crest above the threshold (swithing at up to 20khz)?
... which is why they are not used for "critical listening" situations...
Adrian, 1500va toroids ARE BIG TOROIDS.
My Symphony No.1 amps - check my webpage yet? - are rated at 180watts into 8 ohms, run high bias AB (not pure A) and have about 2.5kVA of toroids in the toroidal PS Mk.II version. All aluminum construction, nothing there to intentionally "bulk it up".
Weight? 128lbs.
Save urself some grief already and buy a commercial high power amp that is bullet proof and does the job already?
Oh, and if you want better results wire the suckers you buy for 240vac input and use 4 x 10ga AC mains wires... but that stuff is heavy too!
As I said, but you ignored, the quality of ur SR/PA is in the mids and the highs. Work on that.
Imho, most bass bins, folded bass horns sound like dog poopie anyhow - THUMP THUMP THUMP just great... but that's merely my very limited experience with these things.
_-_-bear
Adrian, 1500va toroids ARE BIG TOROIDS.
My Symphony No.1 amps - check my webpage yet? - are rated at 180watts into 8 ohms, run high bias AB (not pure A) and have about 2.5kVA of toroids in the toroidal PS Mk.II version. All aluminum construction, nothing there to intentionally "bulk it up".
Weight? 128lbs.
Save urself some grief already and buy a commercial high power amp that is bullet proof and does the job already?
Oh, and if you want better results wire the suckers you buy for 240vac input and use 4 x 10ga AC mains wires... but that stuff is heavy too!
As I said, but you ignored, the quality of ur SR/PA is in the mids and the highs. Work on that.
Imho, most bass bins, folded bass horns sound like dog poopie anyhow - THUMP THUMP THUMP just great... but that's merely my very limited experience with these things.
_-_-bear
bear said:
I did already. I have an RMX5050. The trouble is I need 7 more, slightly heavier duty (4 ohm bridged will be normal operation, not overload). So make it 15 more. I don't have $25,000 to spend, but I've got time. I have about $4000 in parts and supplies to build two batches of four amps.
bear said:
That's what all 8 of my lightweights are for - the uppermid/high boxes. The low mids and subs need the big iron. Most folded horns sound like dog poopie because they either use too short a path length (CV, EV, etc) or too few boxes. Either way you get a massive peak at 90 Hz. You won't with 6 or 8 lab horns grouped.
The stack just produces an eerie, shuddering low end that will rattle your eyeballs and dental fillings out without ripping you new eardrums.
It would cost me 3 times more for a "proven" amp, but I did find a good deal on an Alto amp that I'm currently looking at, but has a europlug on it and have to figgure out if I can work with that.
Honestly, I have no idea what you guys are buying out there.
There is a glut of decent (for this application) powerful amps on the used market.
Find yee any bigish pro sound company, walk in the back door and see what carcasses, surplus and used gear they have loafing about.
Last time I looked even on ebay the cost of a 500watt class amp is way under $1kUSD, and not chinese junk either.
Then too you have choices to make - one big amp for multiple bins/drivers or multiple smaller amps per bin/driver. Which is better? Which is more reliable?
But, wtheck do eye no?
Look, if you can turn out high power amps on the cheap for your own use in a PA system, you MAY be in the wrong business??
But if you can do that, ur not sitting here asking about how to do it.
Buy commercial amps. Even blown ones and fix them. Or use the carcasses for the PS and heatsinks/fans...etc.
Giant toroids and the like are a bit silly given the realities of today's power amp market and what is trying to be done with them in this application.
_-_-bear
There is a glut of decent (for this application) powerful amps on the used market.
Find yee any bigish pro sound company, walk in the back door and see what carcasses, surplus and used gear they have loafing about.
Last time I looked even on ebay the cost of a 500watt class amp is way under $1kUSD, and not chinese junk either.
Then too you have choices to make - one big amp for multiple bins/drivers or multiple smaller amps per bin/driver. Which is better? Which is more reliable?
But, wtheck do eye no?
Look, if you can turn out high power amps on the cheap for your own use in a PA system, you MAY be in the wrong business??
But if you can do that, ur not sitting here asking about how to do it.
Buy commercial amps. Even blown ones and fix them. Or use the carcasses for the PS and heatsinks/fans...etc.
Giant toroids and the like are a bit silly given the realities of today's power amp market and what is trying to be done with them in this application.
_-_-bear
Followed your advice and a local pro audio dealer wanted to sell me a second hand QSC RM2103 ( ??? ) for $740+ TAXES....
yeahhh
i think i will build my own..
yeahhh
i think i will build my own..
Read what I wrote please?
I said SR/PA company.
A touring sound company not a local small time operator.
Not a pro audio dealer.
(although you can get lucky anywhere...)
That and ebay, fwiw.
Do you think you will build one of your proposed amps for less than $740 in parts? Just curious.
_-_-bear
I said SR/PA company.
A touring sound company not a local small time operator.
Not a pro audio dealer.
(although you can get lucky anywhere...)
That and ebay, fwiw.
Do you think you will build one of your proposed amps for less than $740 in parts? Just curious.
_-_-bear
bear said:
I most certainly will...
the expensivest part is the Power supply itself ( 2x$160 for the toroids and 12x$12 caps)
each chanell will run me about $125 + 15 for each board.
PS...
the power output will be a lot more than that QSC amp will be able to swing
I think you have underestimated the cost of building the amp.
is your time worth nothing ?
and the connectors, wiring, proptection circuits etc etc EMC filters
(the list goes on) all adds up
*unless you want to use junked parts*
Good luck with the build though !
Hopefully we see some building of some / any kind soon intead of all talk !!!!
-Dan
is your time worth nothing ?
and the connectors, wiring, proptection circuits etc etc EMC filters
(the list goes on) all adds up
*unless you want to use junked parts*
Good luck with the build though !
Hopefully we see some building of some / any kind soon intead of all talk !!!!
-Dan
Adrculda said:Followed your advice and a local pro audio dealer wanted to sell me a second hand QSC RM2103 ( ??? ) for $740+ TAXES....
yeahhh
i think i will build my own..
Adrculda said:
I most certainly will...
the expensivest part is the Power supply itself ( 2x$160 for the toroids and 12x$12 caps)
each chanell will run me about $125 + 15 for each board.
PS...
the power output will be a lot more than that QSC amp will be able to swing
Friend,
you need to add up what you just said:
2 x $160 = $320 (toroids)
12 X $12 = $144 (caps)
2 X $140 = $280 (boards)
What does that add up to?
That's before chassis, heatsinks, wire, resistors, connectors/relays, transistors, screws, etc. etc. etc.
You can build the amp of your dreams, but realize that buying new parts and building anything is usually much more expensive than the equivalent mass produced, high volume production item.
Do you think that the advice I'm giving comes from out of the air??
_-_-bear
PS. seems to me that in the PASS Labs section here there are some high powered amps, and people who have built them, laid out the boards and are selling them cheaper than you can make ur own... and they are known to work. Maybe consider that?
you need to add up what you just said:
2 x $160 = $320 (toroids)
12 X $12 = $144 (caps)
2 X $140 = $280 (boards)
What does that add up to?
That's before chassis, heatsinks, wire, resistors, connectors/relays, transistors, screws, etc. etc. etc.
You can build the amp of your dreams, but realize that buying new parts and building anything is usually much more expensive than the equivalent mass produced, high volume production item.
Do you think that the advice I'm giving comes from out of the air??
_-_-bear
PS. seems to me that in the PASS Labs section here there are some high powered amps, and people who have built them, laid out the boards and are selling them cheaper than you can make ur own... and they are known to work. Maybe consider that?
expect the amplifier to cost ~ 30% of the total budget, about 30% for the PSU, another 30% for the chassis and heatsink and finally about 10% for the chassis hardware.
danieljw said:
That is the key to the whole thing. Junked parts. Anyone who pays $300 for a toroid is a nut. Or $50 for a cap. You buy surplus for all of the heavy hardware or you don't build amps. Period. When 2200VA worth of toroid cost $60, six 68kuF caps cost $24 (new pulls - I bought two pallets), heat sink stock for $20 for a 17" section, a 4x8 sheet of aluminim stock that builds multiple chassis a mere $75, and buying all the small parts in bulk, the cost of building a small lot can be quite reasonable. Compared to the $1500 for competing (entry level) or $3000 (professional) amps. Each. A rack full of those is a new car. I'm not talking about the little 500 watt units which you can get for $300. I already have enough of those, a some older gerneration homebrew units, and 6 new/used 3kW (yeah right) switchmode units to limp by on low power. I'm trying to get enough power together - around 50k watts - to run the system all the way to its potential.
Ok, I tried to do a quick cost breakdown on the latest project. Turns out the amp is about half, the supply and chassis about half of the remainder each. Of course, this as assuming what I actually paid for stuff, in the qunatities purchased. Some is just conservative guessing as much of it has been acquired over time (been in stock for years) and used on multiple projects.
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Compared to what most people would be paying, if they just started out to build "one" - instead of intentionally stocking up to build a batch and taking advantage of surplus. The amp becomes a smaller fraction of the total, and it's a wash compared to just buying a used Crest. And more expensive than a QSC.
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I got a 2000VA UI-core transformer for about $20 (though shipping was also $20) and 10 10000µF/63V caps for $10 or so IIRC... 😛
Will have to rewind the transformer though, it has a single 80V secondary with almost all power, a 48V CT and a 24V CT IIRC of lower power.
Transistors - bought some non-lead free NJL1302/NJL3281 from Arrow when they sold them out - $1/pc including shipping (bough 125 of each...)! 😱
I also got a blown Crest CA4 and Crest CA9 for $300 total. The CA4 has burned a hole in the power supply/preamp board but contains nice heatsinks, the chassis of course and a 2x60V about 1000VA-1500VA something transformer.
The CA-9 had a totally incinerated preamp board on one channel but I bought a good one from Zero Cool here on the forum so that one will be up and running soon.
Will have to rewind the transformer though, it has a single 80V secondary with almost all power, a 48V CT and a 24V CT IIRC of lower power.
Transistors - bought some non-lead free NJL1302/NJL3281 from Arrow when they sold them out - $1/pc including shipping (bough 125 of each...)! 😱
I also got a blown Crest CA4 and Crest CA9 for $300 total. The CA4 has burned a hole in the power supply/preamp board but contains nice heatsinks, the chassis of course and a 2x60V about 1000VA-1500VA something transformer.
The CA-9 had a totally incinerated preamp board on one channel but I bought a good one from Zero Cool here on the forum so that one will be up and running soon.
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