??? Overboard ???
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URL: https://forum.speakerplans.com/forum_posts.asp?TID=23259
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Topic: ??? Overboard ???
Posted By: _Adrian_
Subject: ??? Overboard ???
Date Posted: 24 January 2009 at 10:55am
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Hey guys... well after pokin around the net and lurkin around here, i came to the conclusion that i have to do something with my spare time and what better to do and try and fry myself trying to build a monster  i came across the http://sound.westhost.com/ - Elliot Sound Products website and a certain http://sound.westhost.com/project117.htm - Project 117 caught my eye... After reading the page several times over came to the demented idea.. I Have To Build one, but not that one must beef it UP!!! so after a couple of hours on the computer i slowly reviewed and "improved" a couple of items: - Power Supply DOUBLED the caps from 8 to 16 10,000uf caps TRIPLED the Transformer from a 2KVA to a 6KVA unit ( in case i want to add a second channel ) RECTIFIERS went from 2 x 35A units to 3 x 50A units Also Bumped the voletage from 135V to 142V (i believe will be 140V) by using a 12v transformer instead of the 6V as well as using 5A rectifiers insted of the 1A ones shown -Amplifier section As of right now... board is in 1 piece, but i will break it into 2 sepparate boards and to help fitting larger heatsink and forced cooling along with slots cut into the board for breathing room for the rezistors. Also number of drivers was increased from 18 to 24. i may do other changes, but thats it for now... so far the powersupply looks like it will be in the $450 range to build ( ~10/cap, $7.50/brigde, $o.55/rezistor $225 for the 2 transformers ) Monday i have to go see a guy about making a few boards, hes got the equipment and the right stuff ( builds custom DC Servo Boards ) and said he does have some boards with some heavy copper on it ( Also uses a CNC Etching machine ) Here's my version of "Project 117".... |
Replies:
Posted By: _Adrian_
Date Posted: 24 January 2009 at 11:27am
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a picture is worth a thousand words someone said... Here they are...    The soft start circuit is basicaly the same, Hopefully wil have the BOM and the rest of the tedious work done tomorow along with entering all the pertinent data on the components... Leave your thoughts.... |
Posted By: odc04r
Date Posted: 24 January 2009 at 12:05pm
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A big project, its going to be heavy but why not ey. I assume you have experience building high power amps? |
Posted By: _Adrian_
Date Posted: 24 January 2009 at 4:57pm
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Car Audio ... YES, and fixed several ones that buddies of mine blew up in misc competitions, but not Pro Audio, with a robust power supply like that and the uprated output stage this would be a perfect workhorse for large bins with power hungry drivers. Besides.... Even as a kid, i had an early fascination with electronics... i still remember the first amp i built Using good ol 2N3055... haha there were no DSP's back then |
Posted By: Elliot Thompson
Date Posted: 25 January 2009 at 12:28pm
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Hello Adrian.
The “117” project offers a lot of similarities of the old Peavey CS 800 A (Non DDT Version). I stumbled upon the design the night before you created this topic and, began comparing notes amongst the two. Your biggest expense would be the power supply. A 6 Kilowatt Transformer is far from cheap these days. Best Regards, ------------- Elliot Thompson |
Posted By: _Adrian_
Date Posted: 25 January 2009 at 7:40pm
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Thanks Elliot, the copper prices these days are crazy, but like any other amplifier the power supply is the heart of the unit, i mean i could theoretically start with 8 caps and the add 8 more, but why ? The way i look at everything i do is "Do it once and d it right" aproach. The only other choice would be a SNMP power supply, but most likely lack the muscle. Also.. would you be kind enough to share the findings ??? Thanks |
Posted By: ceharden
Date Posted: 25 January 2009 at 9:15pm
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This amp uses what I would call a 'brute force' approach. If you really want to acheive this sort of output power you should really be looking at a class G or H design with multiple supply rails to reduce output device dissipation. That or build two smaller amplifier channels that can be bridged. Also, upping the auxiliary supply to 142V from 135V will not increase the power output at all. The output transistors are run from the 130V supply, the higher supply is purely to allow the driver stage some headroom to work in. A switched mode supply although much more difficult to design would in fact be a better solution.... |
Posted By: andyamp
Date Posted: 25 January 2009 at 9:40pm
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by running driver circuit higher than output stage will allow output stage to be driven to saturation. this will increase output power (sine wave) But considered not worth the benefit in gained performance and added cost. also, this helps reduce ripple rejection if done correctly ------------- a wise man changes his mind a fool does not. http://www.matrixamplification.com/ - http://www.matrixamplification.com/ |
Posted By: Elliot Thompson
Date Posted: 25 January 2009 at 10:57pm
The similarities are the power consumption under RMS ESP: “With a peak voltage of 110V, the peak supply current is 27.5A into a 4 ohm load. RMS speaker current is just under 20A at full power.” Peavey: “Due to the high currents (greater than 14 amps) at full output, it is recommended that No.16 or larger wire be used whenever possible.” “It should be connected to a circuit capable of at least 20 amps continuous or greater.” The output transistors used in quantity ESP: 10 MJ15024 transistors for each channel. Peavey: 12 MJ15024 transistors for each channel The lack of using a protection at the output follows the same scheme as the Peavey as well. ESP: “DC Protection - You cannot use output relays with this amplifier! Should a DC fault be detected at the output, the only option is to switch off the power. A relay that will withstand breaking 115V or 150V DC at 25A or more is going to be hard to get, and extremely expensive. Although the speakers will be subjected to the full supply voltage until the filter caps discharge, as the builder of the amp, you are confident that they will withstand the power.” The same thing applies the CS 800A model in terms of playing the unit with the power off to discharge the caps. It does offer a triac to short the outputs if the DC (1 Hz) occurs and destroy all the output transistors on the problem channel to protect your speakers. There is more however, I am not in a very observant mood at the moment.
I agree on not jeopardising the power supply. Many don’t realise that the power supply is more important than having a multitude of watts. Best Regards, ------------- Elliot Thompson |
_Adrian_ wrote:Posted By: _Adrian_
Date Posted: 26 January 2009 at 3:30am
Ahhh so theres some gains, not significant but. as far as the cost ?? It will be minimal as the transformer or toroid will be a custom unit and will be built to my specs. and adding 2 x 12VAC or 15VAC outputs will be minimal rise in cost
interesting though is that i never even was aware of the similarities between the ESP and the Peavey amps, but whats more intruiging though... is my "upgrade" path made the ESP amp section very similiar to the peavey, but now whats on my mind is the power supply specs between the 2 designs, which basicly is a very simple class A operation. As simple as it is and looks and it is... all the grunt comes from the power supply. need a good transformer to start with, good bridges and for sure will have heat sinks on them and good caps are a must! as i Learned in car audio to keep a clean and constant output capacitance is king !!! the only downfall of this in home/pro audio that there will be a large inrush current due to the powersupply "charging" the caps up, but this can be easily solved by having your operating voltage on your center tap as to when powering up we will only see half the voltage across the output of the secondariesand by the means of a zenner we could set up a relay to latch the "operating mode" of the supply to fully charge the caps up for operation. Also this feature can be used to reduce the output of the amplifier as the rail voultage woul only be half of the operating voltage while testing and also would be a plus not having to worry about blowing up low wattage drivers as well. Also with another idea i have been messing with is to relay the power feed to the amplifier section. Each feed with its own relay and own fuse and it would be a better way of protecting your output devices by cutting off the amplifier section from the power supply. |
Posted By: Elliot Thompson
Date Posted: 26 January 2009 at 12:48pm
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The Power Supply in addition to the heat sinks is why the 4ru version of the CS 800 would never get hot. The power supply was severely over designed in the 70’s. With customers requiring amplifiers to offer more watts with the least amount of current drawn from the receptacle today, creating a version to double the wattage with the same performance standards of the CS 800 is going cost more, weigh more, and increase in size. The in-rush current was never solved in any of the old CS lines (400, 800, 800x, 900, 1000,1000X, 1200, & 1200X). The CS 1200/1200X would trip a 15 Amp circuit (120 Volts) upon booting up. Many users would take out one of the fuses (It used two Power Transformers) so the in-rush current of both channels simultaneously would not trip the circuit. Once one channel stabilises, they would insert the other fuse to enable the next channel. The DDT (IGM in BGW) circuitry would monitor the amplifier and compensate the problem by a means of reducing the output level when activated. It would offer up to 20 decibels of compression under the most extreme conditions. The CS 800 "A" never offered DDT however, B, C, "89" and, "X" did. Bare in mind that all the old CS line amplifiers would deliver 20 – 20 kHz sine waves continuously under a 4-ohm load at it’s advertised watts with no more than 0.03% THD until the user decides to stop while still meeting UL requirements. There was no 1/8th or 1/3rd standard that is used today. In the case of the 4ru version, it is very rare the amplifier will get warm, much less hot under the worst (2-ohm per channel stereo mode) case scenario amplifying musical signals. It is not a Class-A amplifier. As I mentioned previously, the ESP design reminded me so much of the Peavey that I took it upon myself to open one of my old CS 800 (A version) to see for myself. There are two caps each rated 15,000, 90 VDC (125 VDC surge) inside the amplifier. Each channel shares the same voltage rail. Each channel offers a voltage rail of is 81 +/- per channel with an output of 40 volts per channel RMS. The Power Transformer that resides in the chassis is slightly under 50% of the enclosure. One could say the ESP design is a CS 800/BGW 750 on steroids for Peavey introduced the CS 800 (Designed by Jack Sondermeyer) in 1976. All this information is readily available on Peavey’s site. Although the BGW 750 is considered better than the Peavey CS 800, they are exactly the same design. Peavey focused more on the struggling artists, while BGW aimed for the elite. So those who turned up their nose to the CS 800 but embrace the 750, are nothing more than audiophiles that have no technical knowledge on the inner twining of the design. Both designs are a product Jack Sondermeyer that worked for RCA before moving to Peavey in 1965. Best Regards, ------------- Elliot Thompson |
Posted By: _Adrian_
Date Posted: 26 January 2009 at 3:04pm
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Ok.. As far as the power supply goes then im on the right track... trying to reduce the initial high current damand that would brown out half the neighbourhod is a bit nutty to everyone's standards now after a care full dissection i moved all the drivers onto a separate board whey they will reside. Also had the ludacris idea of adding more output devices so theres less stress on the drivers and could also drive lower impedances as low as 2ohms in 18 per polarity giving us a grand total of 36 drivers per chanell. ordered a total of 100 drivers ( 50 of each last night ) along with 8 MJE350/340 (4 of each) but hit a stump when it came to the rezistors as there no spec on them besides the rezistance and i would hate to use a low wattage one to cook the board with... what do you guys think .. 5w per driver is enough ??? |
Posted By: Elliot Thompson
Date Posted: 26 January 2009 at 3:34pm
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The only limiting factor would be the heat sink size. In this photo submitted in the following hyperlink, there is only one heat sink (one channel) shown in the CS 800. http://www.speakerplans.com/forum/forum_posts.asp?TID=18854 - http://www.speakerplans.com/forum/forum_posts.asp?TID=18854 Two would be around 16 inches across or deep for 24 transistors using one channel. Thirty-six will take up even more space (24 inches in width or depth for one channel). If you use the above type of heat sinks shown in the hyper link above, your design will operate very cold/slighly warm under any conditions in terms of music. Smaller types will increase the temperature. It may be wiser to use two Power Transformers so you can distribute the power on two AC circuits so, you won't have to current limit the amplifier. Once you begin current limiting the design, your project is lost for that's what it excels on. If you haven’t registered, you might want to join www.diyaudio.com - www.diyaudio.com and, create a topic in the solid state forum. Many designers are about (Old & New) that can tell you what is needed and, what is not. You might even find someone that was brazen enough to build such a design. At the rate you are going, you will approach close to 300 pounds in no time.
Best Regards, ------------- Elliot Thompson |
Posted By: _Adrian_
Date Posted: 27 January 2009 at 2:44am
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UPDATE: dropped off the pre-driver section to have a few board made up. the guy was amazed at first and was wondering if i was building a welder of some sort  When i told him what i was working on he gave me the  look and with a tiny voice he asked if he heard right...Couldn't rezist but had to trow in that i left the flux capacitor out of the diagram since thats the top secret part of it LOL long story short... $50 for 4 boards and got him to order me 2 forced cooling heatsinks, really nice ones at that!! its pretty much a square aluminum tube with copper honeycomb design inside and a wall thickness about 3/16 on the mounting side. dimensions are as follows 120mm x 120mm x 400mm long, and though it was a steal for $70 each. He uses them to keep triac cool disspating over 3500W into the tunnel and keeping it at only 22C. as far as the transformer goes... the closest i found was a monster 8KVA toroid with 2oo/440V primaries and tripple tapped secondaries at 25, 60, 120V on each secondary... $500 EDIT.. need to find BOM so i can start ordering some parts cuz the ones that were on the schematic are there but its incomplete information. |
Posted By: Elliot Thompson
Date Posted: 27 January 2009 at 12:59pm
Very nice Transformer. 
I began looking around for high current transformers and, the author was correct. It is very hard to find a readily available transformer above 1.5kW unless it is customed design. Have you figured out the overall dimensions of this amplifier yet? Best Regards, ------------- Elliot Thompson |
Posted By: Elliot Thompson
Date Posted: 27 January 2009 at 1:47pm
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Mate,
You might want to view this http://www.diyaudio.com/forums/showthread.php?s=54a8947fe10ac8342f280aeda9fc3e6a&threadid=97566&highlight= - this post It may help you add the missing parts that the author did not add. Best Regards, ------------- Elliot Thompson |