Hey Workhorse,
Do you mean series parallel for the output devices? the Yorkville manual you
sent me looks like the devices are in series parallel.
So. . . four devices would be in series with each other, and the other four (in series)
would be parallel with them?
Does this sound right?
Also, How do I calculate the current (I) requirments for the power supply?
Thanks for the info on the caps and rail voltages!
Swagboy.
P.S. It's a Fluke! I just bought me a new Fluke. . . my old meter died. Model 112.
Good enough for what I am doing right now. . .
Do you mean series parallel for the output devices? the Yorkville manual you
sent me looks like the devices are in series parallel.
So. . . four devices would be in series with each other, and the other four (in series)
would be parallel with them?
Does this sound right?
Also, How do I calculate the current (I) requirments for the power supply?
Thanks for the info on the caps and rail voltages!
Swagboy.
P.S. It's a Fluke! I just bought me a new Fluke. . . my old meter died. Model 112.
Good enough for what I am doing right now. . .
Hi Workhorse,
I'm probably just ignorant here, but. . .
I am unsure how to calculate the requirements for current:
According to Ohm, 73.5 volts RMS will be required to dissipate 1200 watts
across a 4ohm load. . . this should require 18.382 Amps (9.191 Amps for
mono per rail, 18.382 Amps for stereo [what I am building] per rail).
If I run a rail at 120 volts, (V*V)/R=3600 Watts. . . not the required 1200 Watts.
The voltage/current relationship changes in Class-G.
can you help me with the math here?
Thanks!
Swagboy
I'm probably just ignorant here, but. . .
I am unsure how to calculate the requirements for current:
According to Ohm, 73.5 volts RMS will be required to dissipate 1200 watts
across a 4ohm load. . . this should require 18.382 Amps (9.191 Amps for
mono per rail, 18.382 Amps for stereo [what I am building] per rail).
If I run a rail at 120 volts, (V*V)/R=3600 Watts. . . not the required 1200 Watts.
The voltage/current relationship changes in Class-G.
can you help me with the math here?
Thanks!
Swagboy
Hi
Please can some one help me with a 150watts/8ohms schematic
and a audio mixer schematic
Thanks
here is my email dnkwenti@gmail.com
i will wait for the link
Please can some one help me with a 150watts/8ohms schematic
and a audio mixer schematic
Thanks
here is my email dnkwenti@gmail.com
i will wait for the link
Hi Swagboy,
your 1200W into 4ohms requires a Vpk=sq root[P*R*2]=root[1200*4*2]=98Vpk.
Ipk=Vpk/R=98/4=24.5Apk.
At very low frequency the speaker can appear as Rload ~=DCR~=0.75*Rnominal, In this situation Ipk can be about 1.33*Vpk/R but this is a very severe test.
For a purely resistive load the Vpk coincides with the Ipk and Vce=[Vrail-Vpk]is low so therefor low device dissipation.
For a reactive load Vpk does not coincide with Ipk and so Vce at Ipk can be much higher than [Vrail-Vpk].
As a rule of thumb the device can see Vce = Vrail @ Ic=half Ipk when load phase is about 45degrees. If you design for this when the rail is low and again when the rail is high then you are getting close to reliability. Worst case is Vce=Vrail when Ic=Ipk.
your 1200W into 4ohms requires a Vpk=sq root[P*R*2]=root[1200*4*2]=98Vpk.
Ipk=Vpk/R=98/4=24.5Apk.
At very low frequency the speaker can appear as Rload ~=DCR~=0.75*Rnominal, In this situation Ipk can be about 1.33*Vpk/R but this is a very severe test.
For a purely resistive load the Vpk coincides with the Ipk and Vce=[Vrail-Vpk]is low so therefor low device dissipation.
For a reactive load Vpk does not coincide with Ipk and so Vce at Ipk can be much higher than [Vrail-Vpk].
As a rule of thumb the device can see Vce = Vrail @ Ic=half Ipk when load phase is about 45degrees. If you design for this when the rail is low and again when the rail is high then you are getting close to reliability. Worst case is Vce=Vrail when Ic=Ipk.
Hi,
now I see why you want the Vpk.
Your maths to arrive at the necessary Vrail is correct, but you have missed out too many terms.
The loss through the transistors, the loss through Re, the rail droop taking account of all the cable losses.
I would allow 1V4, 2V, 15V =18V. add Vpk>=116Vdc
For ClassAB it is quite common to assume the transformer is rated at 1.5 times the output power and this allows for the efficiency of the amp at full power and seems to also allow for a rectifier fed smoothing cap appearing to derate the transformer to 70%. These combined with a music type signal seem to work out. Your lower rails could be calculated as for a ClassAB. When you come to the high rails, you are planning on running them from a voltage tapping on the same transformer? Here efficiency is much higher but you still have the 70% derating for cap loaded transformer. So the decision is;- allow the same 150% as ClassAB or allow a lesser amount. An error here will pull the high rail down further but since it is for a short term peak current only, you have the caps on the line supplying this and you may find that with music signals that the effective droop is more like increased ripple.
Your thought of, suck it and see, might be close enough until an experienced designer comes along and volunteers the information.
now I see why you want the Vpk.
Your maths to arrive at the necessary Vrail is correct, but you have missed out too many terms.
The loss through the transistors, the loss through Re, the rail droop taking account of all the cable losses.
I would allow 1V4, 2V, 15V =18V. add Vpk>=116Vdc
For ClassAB it is quite common to assume the transformer is rated at 1.5 times the output power and this allows for the efficiency of the amp at full power and seems to also allow for a rectifier fed smoothing cap appearing to derate the transformer to 70%. These combined with a music type signal seem to work out. Your lower rails could be calculated as for a ClassAB. When you come to the high rails, you are planning on running them from a voltage tapping on the same transformer? Here efficiency is much higher but you still have the 70% derating for cap loaded transformer. So the decision is;- allow the same 150% as ClassAB or allow a lesser amount. An error here will pull the high rail down further but since it is for a short term peak current only, you have the caps on the line supplying this and you may find that with music signals that the effective droop is more like increased ripple.
Your thought of, suck it and see, might be close enough until an experienced designer comes along and volunteers the information.
I'll help you with some rule-of-thumb power supply numbers.
You can do a search on my name if you want full explanations, I've explained it all before.
Transformer VA: bare minimum=watts you want out. Will sound better up to 2VA for every watt you want out.
Filter caps: 4000µF for 8 ohms, 8000µF for 4 ohms, 15000µF for two ohms, one for each rail per channel. A two rail design that is 'stable' to 2 ohms will need 8 pcs of 15000µF, or 120,000 total (Crest 6000).
For a two-rail design, put the lower rail at half the main rail(most pro amps ±50V, ±100V). For a three-rail, put the medium rail at half the high rail, and the low rail at half the medium rail (Carver M1.0 has ±25V, ±50V, ±100V).
Transformer voltage. Figure out the peak voltage at the impedance you want to drive. 98V(peak)=1200W/4R, subtract about 10%, that's the RMS voltage your transformer will need to be.
So for a 1.2KW/4R amp you would want a 90-45-0-45-90V 2KVA transformer with four 10,000µF~15,000µF at 75V per channel. This will give about ±135V (no load) on the top rail. Crest used a pair of 45-0-45 toroids rated at 1.8KVA each, with a total of four 33,000µF 75V (IIRC).
http://www.crestaudio.com/media/schematics/8001_schematic_set.pdf
The Crest 8000 is about what you want. It has 5 pair of 150W plastic 1302/3281 for outputs, 3 pair of 250W metal MJ21193/94 will replace these. Use the 1302/3281 for drivers (as shown).
Note the front end is virtually identical to the Leach, and so is the tripple EF output stage.
You can do a search on my name if you want full explanations, I've explained it all before.
Transformer VA: bare minimum=watts you want out. Will sound better up to 2VA for every watt you want out.
Filter caps: 4000µF for 8 ohms, 8000µF for 4 ohms, 15000µF for two ohms, one for each rail per channel. A two rail design that is 'stable' to 2 ohms will need 8 pcs of 15000µF, or 120,000 total (Crest 6000).
For a two-rail design, put the lower rail at half the main rail(most pro amps ±50V, ±100V). For a three-rail, put the medium rail at half the high rail, and the low rail at half the medium rail (Carver M1.0 has ±25V, ±50V, ±100V).
Transformer voltage. Figure out the peak voltage at the impedance you want to drive. 98V(peak)=1200W/4R, subtract about 10%, that's the RMS voltage your transformer will need to be.
So for a 1.2KW/4R amp you would want a 90-45-0-45-90V 2KVA transformer with four 10,000µF~15,000µF at 75V per channel. This will give about ±135V (no load) on the top rail. Crest used a pair of 45-0-45 toroids rated at 1.8KVA each, with a total of four 33,000µF 75V (IIRC).
http://www.crestaudio.com/media/schematics/8001_schematic_set.pdf
The Crest 8000 is about what you want. It has 5 pair of 150W plastic 1302/3281 for outputs, 3 pair of 250W metal MJ21193/94 will replace these. Use the 1302/3281 for drivers (as shown).
Note the front end is virtually identical to the Leach, and so is the tripple EF output stage.
Hi DJK,
In my 2.5KW amp The supply voltages are +-50, +-100, +-150V and the transformer is rated at 1.5KW continuous ....Capacitance per tier is 10000mFd..total is 60000mFd ..The rails sag is only 6 volts when fully loaded with 2 ohms and output power is in excess of 2.5KW..Due to rail switching the Tier loading is very less and power consumption from the transformer is also very less as compared to Class-B
regards,
K a n w a r
In my 2.5KW amp The supply voltages are +-50, +-100, +-150V and the transformer is rated at 1.5KW continuous ....Capacitance per tier is 10000mFd..total is 60000mFd ..The rails sag is only 6 volts when fully loaded with 2 ohms and output power is in excess of 2.5KW..Due to rail switching the Tier loading is very less and power consumption from the transformer is also very less as compared to Class-B
regards,
K a n w a r
High powered amplifier
Dear Swagboy,
To deliver 600 watts into 8 ohms means that you must deliver 69.28 volts into the load. taking into account some output stage saturation losses you would have to run it off a +/- 105v supply ASSUMING that the transformer has perfect regulation. Of course this is not possible unless you use a switchmode power supply.
So typically if you use a 1.5Kw transformer for each channel you will have to run the supplies at +/-120 to +/-130v under idle.
There are not that many BJTs that you can buy in complementary pairs which handle this voltage.
Mosfets are horribly pricey at these voltage-current levels.
You have some choices.
1) Run the output stage in a series configuration. This allows you to use LESS output devices for a given supply rail as the devices now run off a lower supply (50% in this case) and if you examine the safe operating area curves for any power device, they are much less prone to secondary breakdown at lower Vceo. So at +/-130v static rails, your devices if run in series, ONLY "see" +/-65v DC. I have referred to my spreadsheets for the large Toshiba 2SC5200/2SA1943 pairs and at +/- 65v, to be safe into 4 ohms and temperature derated the devices to 80 deg C, you would need 3 devices in parallel in each series bank. This would mean a total of 12 output devices per channel. Comparing this to running a standard parallel set of devices of only a +/-110v rail you would need 7 +7 devices. I do not have spreadsheet numbers at +/-130v but if at 110v you need more then at 130v it would be worse. We have built thousands of this type of output stage with an extremely low failure rate.
2) Run a multi rail class G system and you improve matters more (Though you have to add in the rail switching devices). But if you had say three rails say 45v per rail stacked, then the output devices only "see" about 50v rails and then you can go down to 2+2 devices as the pure outputs, and then add the necessary rails switchers.
3) Class D. This has to be the best solution as the average efficiency is so much better, the power supply becomes smaller (Class B amps basically ask the power supply for energy whcih is promptly dumped into the heatsinks as heat) and the power supply is pretty dumb and simply supplies what the amp demands whether it goes to the speaker or not. This soloution demands ultimate PCB design and layout and is not for the novice as I believe a 600/1200w amplifier is not for the novice.
Back in 1972 I built a 1.5Kw @ 8 ohm per channel home amplifier and it took me 18 months to complete and I had been building amps for many years before this. (www.zedaudio.com)
Dear Swagboy,
To deliver 600 watts into 8 ohms means that you must deliver 69.28 volts into the load. taking into account some output stage saturation losses you would have to run it off a +/- 105v supply ASSUMING that the transformer has perfect regulation. Of course this is not possible unless you use a switchmode power supply.
So typically if you use a 1.5Kw transformer for each channel you will have to run the supplies at +/-120 to +/-130v under idle.
There are not that many BJTs that you can buy in complementary pairs which handle this voltage.
Mosfets are horribly pricey at these voltage-current levels.
You have some choices.
1) Run the output stage in a series configuration. This allows you to use LESS output devices for a given supply rail as the devices now run off a lower supply (50% in this case) and if you examine the safe operating area curves for any power device, they are much less prone to secondary breakdown at lower Vceo. So at +/-130v static rails, your devices if run in series, ONLY "see" +/-65v DC. I have referred to my spreadsheets for the large Toshiba 2SC5200/2SA1943 pairs and at +/- 65v, to be safe into 4 ohms and temperature derated the devices to 80 deg C, you would need 3 devices in parallel in each series bank. This would mean a total of 12 output devices per channel. Comparing this to running a standard parallel set of devices of only a +/-110v rail you would need 7 +7 devices. I do not have spreadsheet numbers at +/-130v but if at 110v you need more then at 130v it would be worse. We have built thousands of this type of output stage with an extremely low failure rate.
2) Run a multi rail class G system and you improve matters more (Though you have to add in the rail switching devices). But if you had say three rails say 45v per rail stacked, then the output devices only "see" about 50v rails and then you can go down to 2+2 devices as the pure outputs, and then add the necessary rails switchers.
3) Class D. This has to be the best solution as the average efficiency is so much better, the power supply becomes smaller (Class B amps basically ask the power supply for energy whcih is promptly dumped into the heatsinks as heat) and the power supply is pretty dumb and simply supplies what the amp demands whether it goes to the speaker or not. This soloution demands ultimate PCB design and layout and is not for the novice as I believe a 600/1200w amplifier is not for the novice.
Back in 1972 I built a 1.5Kw @ 8 ohm per channel home amplifier and it took me 18 months to complete and I had been building amps for many years before this. (www.zedaudio.com)
Ok. . .
let's try trial and error.
What I'm gathering from what everybody is saying is that I can run my Class-G Amp
thusly. . .
Stereo (two channel) Class-G
600 watts @ 8ohms, 1200 watts @ 4ohms
+/- 120V and +/-60V rails
1.5 KVA to 2 KVA power transformer
8 pairs of MJL21193/MJL21194's in series parallel (four series parallel to four series).
Power Supply: 1.5 to 2KVA transformer
Assuming at LEAST 6V of losses (more depending on who you talk to):
120Vpk rails would require 90V RMS secondaries
60Vpk rails would require 49-50V RMS secondaries
Assuming 1KVA per set of secondaries would yield:
+/- 90V 5.6 Amp secondaries
+/- 50V 10.0 Amp secondaries
Is the assumption of splitting the VA correct?
Does this sound about right to anyone?
Worst case senario, will it work at all?
Thanks!
Swagboy
let's try trial and error.
What I'm gathering from what everybody is saying is that I can run my Class-G Amp
thusly. . .
Stereo (two channel) Class-G
600 watts @ 8ohms, 1200 watts @ 4ohms
+/- 120V and +/-60V rails
1.5 KVA to 2 KVA power transformer
8 pairs of MJL21193/MJL21194's in series parallel (four series parallel to four series).
Power Supply: 1.5 to 2KVA transformer
Assuming at LEAST 6V of losses (more depending on who you talk to):
120Vpk rails would require 90V RMS secondaries
60Vpk rails would require 49-50V RMS secondaries
Assuming 1KVA per set of secondaries would yield:
+/- 90V 5.6 Amp secondaries
+/- 50V 10.0 Amp secondaries
Is the assumption of splitting the VA correct?
Does this sound about right to anyone?
Worst case senario, will it work at all?
Thanks!
Swagboy
nobody mentioned rod elliott latest project yet at www.sound.au.com ?
1500 watt and all warnings are included ...
1500 watt and all warnings are included ...
Nkwenti, what use is the mixer for? Is for DJ use? Or is it for live sound use? How many inputs are required?
I like the Leach amp very much, but it may be a bit much for a first project. The M250 (one of the designs Andrew mentioned) would serve you well, and is less complex. It is well discussed and documented in other threads on this board. A 45-0-45V 500VA~1KVA transformer and a pair of 15,000µF~20,000µF filter caps would work for the supply.
K a n w a r, your amp sounds like a real brute! I'm glad you shared some of the details with us.
"But if you had say three rails say 45v per rail stacked, then the output devices only "see" about 50v rails "
MOER , your understanding of voltage requirements is incomplete. In a class AB amp the outputs must be able to withstand the peak-to-peak rail voltages. In class G or H they must be able to withstand the peak from the lowest negative rail to the highest positive rail (ie: for ±65V and ±130V rails for a 1.2KW/4R amp you need outputs rated at a minimum of -65V + 130V = 195V). The outer bank of outputs would only need to withstand 65V in this example, but the inner set of outputs will see up to 195V on transients during clipping.
I like the Leach amp very much, but it may be a bit much for a first project. The M250 (one of the designs Andrew mentioned) would serve you well, and is less complex. It is well discussed and documented in other threads on this board. A 45-0-45V 500VA~1KVA transformer and a pair of 15,000µF~20,000µF filter caps would work for the supply.
K a n w a r, your amp sounds like a real brute! I'm glad you shared some of the details with us.
"But if you had say three rails say 45v per rail stacked, then the output devices only "see" about 50v rails "
MOER , your understanding of voltage requirements is incomplete. In a class AB amp the outputs must be able to withstand the peak-to-peak rail voltages. In class G or H they must be able to withstand the peak from the lowest negative rail to the highest positive rail (ie: for ±65V and ±130V rails for a 1.2KW/4R amp you need outputs rated at a minimum of -65V + 130V = 195V). The outer bank of outputs would only need to withstand 65V in this example, but the inner set of outputs will see up to 195V on transients during clipping.
"nobody mentioned rod elliott latest project "
The MJ15024/25 only have 100W SOA at 100V and that amp will blow up in your face.
The original Crown VZ5000 is 1.3KW at 8 ohms, and uses the MJ15024/25 in a bridged quasi class H design so they have the full 250W SOA available.
In case you haven't figures it out yet, the ESP project is a joke.
"Is the assumption of splitting the VA correct?"
Hmmm, I would do exactly what Crest did and run two identical 45-0-45 in series.
The Crest 8000 was probably the most used amp in pro sound hire companies (touring) for bass (until they came out with even larger, newer designs).
You will also be able to find surplus 40-0-40V and 45-0-45V transformers (40-0-40V is only 1dB less power), You could use two small 800VA ones per channel, or one pair of 1.5KVA ones similar to what Crest did.
"8 pairs of MJL21193/MJL21194's in series parallel (four series parallel to four series)."
Yes, 4 devices per rail, 8 pair per channel total, is pretty conservative.
"Worst case senario, will it work at all?"
You can build it up with the front end and just the lower tier of outputs connected for check-out purposes, and add the top tier after you have the lower one working OK. With 4 pair of outputs and a pair of 45-0-45V transformers, the lower tier alone will put out about 600W into 2 ohms.
The MJ15024/25 only have 100W SOA at 100V and that amp will blow up in your face.
The original Crown VZ5000 is 1.3KW at 8 ohms, and uses the MJ15024/25 in a bridged quasi class H design so they have the full 250W SOA available.
In case you haven't figures it out yet, the ESP project is a joke.
"Is the assumption of splitting the VA correct?"
Hmmm, I would do exactly what Crest did and run two identical 45-0-45 in series.
The Crest 8000 was probably the most used amp in pro sound hire companies (touring) for bass (until they came out with even larger, newer designs).
You will also be able to find surplus 40-0-40V and 45-0-45V transformers (40-0-40V is only 1dB less power), You could use two small 800VA ones per channel, or one pair of 1.5KVA ones similar to what Crest did.
"8 pairs of MJL21193/MJL21194's in series parallel (four series parallel to four series)."
Yes, 4 devices per rail, 8 pair per channel total, is pretty conservative.
"Worst case senario, will it work at all?"
You can build it up with the front end and just the lower tier of outputs connected for check-out purposes, and add the top tier after you have the lower one working OK. With 4 pair of outputs and a pair of 45-0-45V transformers, the lower tier alone will put out about 600W into 2 ohms.
swagboy said:
Hi Swagboy,
If you want 1200W @ 4 Ohms, then use atleast 10 Pairs of MJL21193/94 devices...Series / Parallel
Since the upper Tier Secondary windings are loaded only when Peaks are encountered therefore your supply configuration is good with respect to music signals...
djk said:
Hi DJK,
Its only because of "You & Chris [Anatech]" the state of art information you guys have given. I am able to research and develop some thing which is first of its kind in this world...All N-channel Vertical Mosfet Class-H in Every Tier......
Thanks Alot,
K a n w a r
Hello Djk
I need it for Dj use and it should have 6inputs .and other audio efect .with 5band eq
i took a look at the m250 cool schematics but i still have problems geting these specs the mje350/340 and the 15030/15031
have you any web that i can buy them or what are the common kinds that should be replaced with
thanks
I need it for Dj use and it should have 6inputs .and other audio efect .with 5band eq
i took a look at the m250 cool schematics but i still have problems geting these specs the mje350/340 and the 15030/15031
have you any web that i can buy them or what are the common kinds that should be replaced with
thanks
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