thank you steven
yes i have years building other audio items like speakers , 323 pair so far and working on 324 as we speak.
building the boards is no problem just not knowing or ever reading schematics.
so i guess i need to start a list as in r1,2,3,4--- and c1,2,3,4 and so on right?
You are building a mosfet output board so you can't use the normal Slewmaster output board schematic.[/QUOTE]
now you lost me again
printed from os site slew main schematic called slewmaster ops main.
if this is from his site and can't be used what now?
how is anyone going to know this.
man this is a crazy to find info project.
There's an LED missing in that schematic. This is the schematic Valery posted yesterday.
Attachments
Hi Gordie,
Feel free to ask questions. Most of us are subscribed to the thread so we are monitoring. It is not a difficult amp to build at all. No tricky parts to find and it is not real picky matching. Jason did a beautiful job designing these boards and for the most part the values are all right there on the boards. The cap values are in code so it is easier to just get those from the schematic. For the rest, you could literally build the amp by just following the screenprint. IMO there is no real advantage to building the HEXFET version over the BJT. It is just another option. A good place for you to start would be to make a Bill Of Materials list and post it here. That will serve a couple of functions. One it will help you familiarize yourself with the circuit and secondly, we can check your selections for accuracy. I don't think any of us placed an order for the whole thing as most of us have developed a part bit of sorts so we just order the things we are missing. Because of this, it is not likely that any of us have a complete Mouser BOM. However, Mouser carries all of the parts you will need to build this amp. I suspect you will become a lot more familiar with how Mouser's parts search engine works by the time you finish.
Blessigs, Terry
Feel free to ask questions. Most of us are subscribed to the thread so we are monitoring. It is not a difficult amp to build at all. No tricky parts to find and it is not real picky matching. Jason did a beautiful job designing these boards and for the most part the values are all right there on the boards. The cap values are in code so it is easier to just get those from the schematic. For the rest, you could literally build the amp by just following the screenprint. IMO there is no real advantage to building the HEXFET version over the BJT. It is just another option. A good place for you to start would be to make a Bill Of Materials list and post it here. That will serve a couple of functions. One it will help you familiarize yourself with the circuit and secondly, we can check your selections for accuracy. I don't think any of us placed an order for the whole thing as most of us have developed a part bit of sorts so we just order the things we are missing. Because of this, it is not likely that any of us have a complete Mouser BOM. However, Mouser carries all of the parts you will need to build this amp. I suspect you will become a lot more familiar with how Mouser's parts search engine works by the time you finish.
Blessigs, Terry
guys tonite you have me dumb founded
mosfet ? i was told this board uses hexfet which i have on order. so which is it?
the above schematic is nothing like what is from os site.
if you could understand from my view of outside looking in, this is nuts.
you all know more , i have no direction at all.
now i don't know where to start or how to start.
mosfet ? i was told this board uses hexfet which i have on order. so which is it?
the above schematic is nothing like what is from os site.
if you could understand from my view of outside looking in, this is nuts.
you all know more , i have no direction at all.
now i don't know where to start or how to start.
You can run Hexfets in these boards but you need to follow the Hexfet schematic and do a little modifying on the board. If you want to run BJT outputs you need to follow the standard schematic and use the boards as is.
The beauty of these boards is there are tons of options to choose from. The only problem with that is it can be intimidating to the first time builder. The only way around this is to bite the bullet and build a set. Don't be afraid to buy spare parts. These things are addictive. You'll want to build more. I think Terry's up to about 8 amplifiers a week by now.
Hexfets will likely be the best power handling device you could choose. Sanken MT-200 devices are a close second. There are some other choices available over in Europe but aren't likely worth the hassle and expense to get them here.
The beauty of these boards is there are tons of options to choose from. The only problem with that is it can be intimidating to the first time builder. The only way around this is to bite the bullet and build a set. Don't be afraid to buy spare parts. These things are addictive. You'll want to build more. I think Terry's up to about 8 amplifiers a week by now.
Hexfets will likely be the best power handling device you could choose. Sanken MT-200 devices are a close second. There are some other choices available over in Europe but aren't likely worth the hassle and expense to get them here.
Hexfet is another name for Vertical MOSFET. If you bought IRFP240/9240 you are golden. A little history. A few months ago OS had to move and because of that he was gone for two or three months. Us Slewmaster fans got bored and in a effort to keep the thread interesting, Valery provided some IPS units as well as the idea to use vertical MOSFETs with the Slewmaster OPS. A few of us built it. It works great and takes fewer parts. The hexfets are a little cheaper too. You're going to be fine, don't panic we are here for you.
Blessings, Terry
Blessings, Terry
OK, you sound like you are a little overwhelmed. Step back, take a breath and relax. All will be well. Please let me know if I get too basic on you, but you seem new to some of the stuff we have been talking about so I will explain as best I can.
The term MOSFET covers a very broad variety of devices. HEXFET is a type of MOSFET, an 'enhancement mode' type of device with a 'cellular' vertical architecture. In the case of what you are talking about, if I understand you correctly, is that you chose to order some IRFP240 and IRFP9240, which are International Rectifier's HEXFET technology, now available via second source supplier such as Vishay. There is nothing wrong with using these.
Let me try clarify the situation, hopefully. The designer, ostripper, created the circuit as a BJT based 'Triple EF' style output stage. At some point, both myself and Valery were thinking that vertical MOSFETs would also be usable with the boards that were already laid out. After some trials we found an arrangement that allowed the use of the boards with vertical MOSFETs. We ultimately settled on using one stage of BJTs to drive the gates of the MOSFETs and modified the bias circuit to get good thermal behavior from the MOSFET devices. The MOSFET 'option' will require you to follow the modified schematic. Not a big deal, just be aware that a few parts are replaced with jumpers, some left off entirely and one part (the LED) was never in the original design. The boards do not have to be cut or damaged to go with MOSFETs.
If you are really new to this type of build you have a couple choices to make. You have the MOSFETs already on order, so you can choose to use them with the understanding that the arrangement was developed after the boards were already in existence as a BJT based design, or switch to BJTs and build it as ostripper originally designed.
One of the nice aspects of this design is that it is modular. You can build and functionally check the individual boards on their own. If the OPS is making you uneasy, start with the IPS.
The term MOSFET covers a very broad variety of devices. HEXFET is a type of MOSFET, an 'enhancement mode' type of device with a 'cellular' vertical architecture. In the case of what you are talking about, if I understand you correctly, is that you chose to order some IRFP240 and IRFP9240, which are International Rectifier's HEXFET technology, now available via second source supplier such as Vishay. There is nothing wrong with using these.
Let me try clarify the situation, hopefully. The designer, ostripper, created the circuit as a BJT based 'Triple EF' style output stage. At some point, both myself and Valery were thinking that vertical MOSFETs would also be usable with the boards that were already laid out. After some trials we found an arrangement that allowed the use of the boards with vertical MOSFETs. We ultimately settled on using one stage of BJTs to drive the gates of the MOSFETs and modified the bias circuit to get good thermal behavior from the MOSFET devices. The MOSFET 'option' will require you to follow the modified schematic. Not a big deal, just be aware that a few parts are replaced with jumpers, some left off entirely and one part (the LED) was never in the original design. The boards do not have to be cut or damaged to go with MOSFETs.
If you are really new to this type of build you have a couple choices to make. You have the MOSFETs already on order, so you can choose to use them with the understanding that the arrangement was developed after the boards were already in existence as a BJT based design, or switch to BJTs and build it as ostripper originally designed.
One of the nice aspects of this design is that it is modular. You can build and functionally check the individual boards on their own. If the OPS is making you uneasy, start with the IPS.
Did you need to cut a trace for the LED or did you get creative with one leg on Q104?
Hi GKF!
So, first you need to get the PCBs (either original Slewmaster, or the one Marc just presented above) and order the required parts. For better understanding - schematic in post #406 is correct. I just was too lazy to re-draw it, so I have only showed the changes. I also did not re-draw the mosfets instead of BJTs, only changed their names.
Now, based on that, Marc went further, and now we have the full schematic and even a Pcb, fully following it (post #414).
Feel free to ask if you have questions
Cheers,
Valery
P.S. This design works fine with both 3 or 5 pairs of the output devices (depends on your power requirements).
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guys overwhelmed is putting it lightly.
all of you have to remember i have spent last 10 years in tube land, never looked at or cared about solid state at all. so i know nothing as a first timer.
so we need to get to the bottom of this with exact correct info period.
all i can tell you about my boards is they are marked slewmonster 5p ef3 ops.
i bought a matched set of 20 irfp240 and irfp9240.
power is what i am after more the better as long as i will not do damage to it.
i want these to be cost no object as they will be maybe my last build.
so if there is a better mosfet i need to know
all of you have to remember i have spent last 10 years in tube land, never looked at or cared about solid state at all. so i know nothing as a first timer.
so we need to get to the bottom of this with exact correct info period.
all i can tell you about my boards is they are marked slewmonster 5p ef3 ops.
i bought a matched set of 20 irfp240 and irfp9240.
power is what i am after more the better as long as i will not do damage to it.
i want these to be cost no object as they will be maybe my last build.
so if there is a better mosfet i need to know
If you can build with tubes then there is no reason solid state should be too daunting, just different.
No issue with the MOSFETs. That particular type is actually pretty well suited to use in audio, in so far as the vertical variety goes. They are used quite often and are pretty durable. Your boards will only work with either BJTs or vertical MOSFETs; lateral MOSFETs are not pin compatible. The output devices will likely be one of the last things you actually install. If you want to avoid any issues relating to the MOSFET 'interpretation' you could switch out to BJTs now before you even begin the build. If it were myself and I already had the MOSFETs, I'd go ahead and use them. Totally up to you at this point. Both MOSFETs and BJTs have their pros and cons; done right I don't feel one is really any better or worse than the other.
What do you have so far besides the boards and MOSFETs? Do you also have some basic test gear such as an oscilloscope and signal generator?
As a rough guide, I generally build in this sequence:
Power Supply first, you need it anyway and you can use it for testing. If you do not have at least a mains bulb limiter to keep mistakes from causing damage, this is also the time to build one with inexpensive hardware store parts (diagram attached). The bulb limiter also saved a grievous mistake on my part as it alerted me to the issue - I had gotten my board turned around when installing the output devices and had them all installed with the wrong polarity devices NPN<>PNP! No damage. A variac is a nice thing to use as well, if you already own one, but I wouldn't buy one for a single build.
Output Stage next, if you have your case or at least heat sinks. This part is really more 'mechanical' with laying out the holes, drilling, tapping and so forth. Drilling templates have been created and posed. Once you have a power supply and one output board you can actually basically do a functional test equivalent to 'idling' the amplifier. Using the bulb limited supply you can catch any assembly issues and get things to where you can adjust bias and verify its setting and stability.
Input Stage next. This can also be tested in isolation and initial adjustments performed. Lesser possibility of damage in this step as well. If you are not in a position to build the output stage first then go ahead and build the input stage first. This might even help warm you up to working with solid state before working with the output stage.
Then you marry the two sections, adjust again and test. When it looks good you can run the power supply without the limiter, make final adjustments and give it a true test. Of course, you can add auxiliary items towards the end if you care to.
No issue with the MOSFETs. That particular type is actually pretty well suited to use in audio, in so far as the vertical variety goes. They are used quite often and are pretty durable. Your boards will only work with either BJTs or vertical MOSFETs; lateral MOSFETs are not pin compatible. The output devices will likely be one of the last things you actually install. If you want to avoid any issues relating to the MOSFET 'interpretation' you could switch out to BJTs now before you even begin the build. If it were myself and I already had the MOSFETs, I'd go ahead and use them. Totally up to you at this point. Both MOSFETs and BJTs have their pros and cons; done right I don't feel one is really any better or worse than the other.
What do you have so far besides the boards and MOSFETs? Do you also have some basic test gear such as an oscilloscope and signal generator?
As a rough guide, I generally build in this sequence:
Power Supply first, you need it anyway and you can use it for testing. If you do not have at least a mains bulb limiter to keep mistakes from causing damage, this is also the time to build one with inexpensive hardware store parts (diagram attached). The bulb limiter also saved a grievous mistake on my part as it alerted me to the issue - I had gotten my board turned around when installing the output devices and had them all installed with the wrong polarity devices NPN<>PNP! No damage. A variac is a nice thing to use as well, if you already own one, but I wouldn't buy one for a single build.
Output Stage next, if you have your case or at least heat sinks. This part is really more 'mechanical' with laying out the holes, drilling, tapping and so forth. Drilling templates have been created and posed. Once you have a power supply and one output board you can actually basically do a functional test equivalent to 'idling' the amplifier. Using the bulb limited supply you can catch any assembly issues and get things to where you can adjust bias and verify its setting and stability.
Input Stage next. This can also be tested in isolation and initial adjustments performed. Lesser possibility of damage in this step as well. If you are not in a position to build the output stage first then go ahead and build the input stage first. This might even help warm you up to working with solid state before working with the output stage.
Then you marry the two sections, adjust again and test. When it looks good you can run the power supply without the limiter, make final adjustments and give it a true test. Of course, you can add auxiliary items towards the end if you care to.
Attachments
the 240/9240 will be fine. You have enough of them so populate all five pairs.
I like to make a list of all the parts as per the schematic. Then I sit with the boards in front of me and using the mouser or digikey site choose the parts being mindful of not just the values but also size and pin spacing. This can take some time but is better then getting a bunch of stuff that does not fit the board.
On my mosfet slewmaster I used fairchild fjl43150/42150 parts as drivers, otherwise I used what the schematic called for.
I'll post some photos of the completed boards when I get to my home computer
I like to make a list of all the parts as per the schematic. Then I sit with the boards in front of me and using the mouser or digikey site choose the parts being mindful of not just the values but also size and pin spacing. This can take some time but is better then getting a bunch of stuff that does not fit the board.
On my mosfet slewmaster I used fairchild fjl43150/42150 parts as drivers, otherwise I used what the schematic called for.
I'll post some photos of the completed boards when I get to my home computer
jason
i have ordered 2 626va 55-0-55, 2 10 x 6 heatsink and 2 5 x 6 heatsink. these will be high freq tig welded together to end up at 15 x 6. chassis are being worked on now . these are going to look tenor ampish. 10 irfp 240 and 10 irfp9240, soft starts each amp will have 60000uf cap and dual rectifiers.
i can build anything, fab anything, weld anything, machine anything.
i have no test gear just my ears
building tube amps are simple due to point to point wire no boards.
i have never heard the term bjt and have no clue what you are talking about.
you know a person does not need to be a electronic tech to build anything just need basic skills and a desire to . i have all that but just that.
i have used safety resistors on each leg before with great results .
terry posted the cfa schematic above , this took about 1 hour to do material list.
he also posted the ops schematic showing red boxes and green lines what is this about?
so if my boards i have are made the way they are what mosfet to use in it that way without board changes?
i have ordered 2 626va 55-0-55, 2 10 x 6 heatsink and 2 5 x 6 heatsink. these will be high freq tig welded together to end up at 15 x 6. chassis are being worked on now . these are going to look tenor ampish. 10 irfp 240 and 10 irfp9240, soft starts each amp will have 60000uf cap and dual rectifiers.
i can build anything, fab anything, weld anything, machine anything.
i have no test gear just my ears
building tube amps are simple due to point to point wire no boards.
i have never heard the term bjt and have no clue what you are talking about.
you know a person does not need to be a electronic tech to build anything just need basic skills and a desire to . i have all that but just that.
i have used safety resistors on each leg before with great results .
terry posted the cfa schematic above , this took about 1 hour to do material list.
he also posted the ops schematic showing red boxes and green lines what is this about?
so if my boards i have are made the way they are what mosfet to use in it that way without board changes?