Just a second, I can't wait till mine are finished either. It is taking so long that sometimes I forget I am building them. 
Yes, I'm getting the urge to finish mine as well. Gotta get the heatsinks and case together first. I bought a smaller Toroid after posting above. I read a little more and realized that the 62+62 VAC was going to result in 86 volt rails which are too much for this amp
I bought a 45+45 VAC toroid instead. You can see it here.
Hopefully this will get me close. It seems that 50VAC would put me right at 70 volt rails, which is what Rod lists as max. Why do us guys always have to strive for the maximum?
I'm going to try and build my own case once my heatsink get's here. I hope it's big enough.
Blessings, Terry
I bought a 45+45 VAC toroid instead. You can see it here.
Hopefully this will get me close. It seems that 50VAC would put me right at 70 volt rails, which is what Rod lists as max. Why do us guys always have to strive for the maximum?
I'm going to try and build my own case once my heatsink get's here. I hope it's big enough.
Blessings, Terry
just to motivate u Terry and co,
im not far from done on my variation , been
all weekend to knock up the case out of some scrap aluminum i picked up, just needs more polishing.
rest will be done as soon as i finish wiring everything up, and adding some sheilds around the preamp (this is kind of an intergrated amp without a selector switch for the itme being)
Terry , if my enclosure looks big enough to u, for the record its
12 x 17 x 4 inches internal volume, gives u an idea of what you can fit in there.
.
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im not far from done on my variation , been
all weekend to knock up the case out of some scrap aluminum i picked up, just needs more polishing. rest will be done as soon as i finish wiring everything up, and adding some sheilds around the preamp (this is kind of an intergrated amp without a selector switch for the itme being)
Terry , if my enclosure looks big enough to u, for the record its
12 x 17 x 4 inches internal volume, gives u an idea of what you can fit in there.
An externally hosted image should be here but it was not working when we last tested it.
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An externally hosted image should be here but it was not working when we last tested it.
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An externally hosted image should be here but it was not working when we last tested it.
mAJORD,
Really nice work!
Is it Rod's volume/sound contol you're using?
Terry,
I'm concerned about your heat sink temperature. I have no specs on it, but it seems a little on the small side for this kind of amp, running at max ratings. If you insist on using this one (cut in two), I would consider making the feet of the enclosure high enough for you to mount a row of the small 4x4 cm fans underneath, or have a big, slow-rotating one at the back with an air-flow channel to send it up from the bottom of the sinks. I would not use fans to begin with, but pe prepared for them.
Another thing... Have you tried to place the components on a table, marked for size, and see how it will all fit?
I'm beginning to worry for you to run out of space.
Jennice
Really nice work!
Is it Rod's volume/sound contol you're using?Terry,
I'm concerned about your heat sink temperature. I have no specs on it, but it seems a little on the small side for this kind of amp, running at max ratings. If you insist on using this one (cut in two), I would consider making the feet of the enclosure high enough for you to mount a row of the small 4x4 cm fans underneath, or have a big, slow-rotating one at the back with an air-flow channel to send it up from the bottom of the sinks. I would not use fans to begin with, but pe prepared for them.
Another thing... Have you tried to place the components on a table, marked for size, and see how it will all fit?
I'm beginning to worry for you to run out of space.
Jennice
thanks jennice,
yes it is a p97 preamp id made earlier, which i need to get rid of the tl027s , and perhaps get some better caps in the signal path , it sounds harsh atm
, no matter what amp i connect it to
yes it is a p97 preamp id made earlier, which i need to get rid of the tl027s , and perhaps get some better caps in the signal path , it sounds harsh atm
, no matter what amp i connect it toHi still4given,
did you parallel the primary tappings to do the load test in post119?
I think if you under run the 230vac tapping at 120vac you will get misleading results. Any comment anyone?
For a transformer this size the volts drop at the secondary seems very high, over 8% lost at 1020va. Could this be due to wrong volts at input? I would expect 3 to 5% regulation on this transformer.
regards Andrew T.
did you parallel the primary tappings to do the load test in post119?
I think if you under run the 230vac tapping at 120vac you will get misleading results. Any comment anyone?
For a transformer this size the volts drop at the secondary seems very high, over 8% lost at 1020va. Could this be due to wrong volts at input? I would expect 3 to 5% regulation on this transformer.
regards Andrew T.
mAJORD,
The Opamps Rod use are ok, but nothing specil. I am satisfied with analog Dev's OP275. If you decide to try them, please let me know what the result is (or if you make any other hanges, which result in changed audio).
AndrewT,
I think the transformer was tries at the 115V primary terminal.
That a transformer is rated 1 kW doers not mean that it behaves well at 1kW. You can optimize for low output impedance, low idle dissapation (spelling???) etc. It is also a matter of losses, material choice and stray field.
It's hypothetical since Terry bought another one, but I'm sure it would have made a very sturdy PSU for any 2x200W amp, with all the caps he has at hand. 😀 (And a nice, stinking bomb, as they aren't rated high enough voltage, if I recall correctly
)
Anyway...
I have put some pics of my line-up (allocation of space in my amp) as I plan it to be. You should (hopefully) be able to see them at ftp://sylvest.dyndns.dk . The bottom (and top, which is not shown in the pics) is made of 1mm metal sheet, bent into U-shapes for strength (the top will be flat). The rear part of the U-profile will also be the back plate of the amp, where the terminals will be fitted. The heat sinks (2 side-by-side, on each side) give an overall depth of 36cm, and 10cm height. Width will be standard 43cm. The parts will be supported by 20 x 30 mm L-shaped aluminum profiles. The feet will be 15mm high, 55 mm diameter aluminum pieces (not pictured). The idea is that they will be big enough for them tu directly support the weight of the heat sinks, and what else may be stacked onto these, without the strain being put on the screws and L-profiles.
I still need to find the right place for the extra switch mode PSU and the power / soft start / audio-output-relay switching circuit. also, I bought a pack (200 pcs) of small M3x18 mm screws in black (the hardened ones, but bought for the colour). US$70 !!! Speaking of "getting screwed"!!! (Sorry, moderators, I just couldn't resist it!) We're not talking rare metal screws or anything... just standard industrial screws, for crying out loud! That price is outrageous, but there is only one place around here that sells them 🙁
Jennice
The Opamps Rod use are ok, but nothing specil. I am satisfied with analog Dev's OP275. If you decide to try them, please let me know what the result is (or if you make any other hanges, which result in changed audio).
AndrewT,
I think the transformer was tries at the 115V primary terminal.
That a transformer is rated 1 kW doers not mean that it behaves well at 1kW. You can optimize for low output impedance, low idle dissapation (spelling???) etc. It is also a matter of losses, material choice and stray field.
It's hypothetical since Terry bought another one, but I'm sure it would have made a very sturdy PSU for any 2x200W amp, with all the caps he has at hand. 😀 (And a nice, stinking bomb, as they aren't rated high enough voltage, if I recall correctly
)Anyway...
I have put some pics of my line-up (allocation of space in my amp) as I plan it to be. You should (hopefully) be able to see them at ftp://sylvest.dyndns.dk . The bottom (and top, which is not shown in the pics) is made of 1mm metal sheet, bent into U-shapes for strength (the top will be flat). The rear part of the U-profile will also be the back plate of the amp, where the terminals will be fitted. The heat sinks (2 side-by-side, on each side) give an overall depth of 36cm, and 10cm height. Width will be standard 43cm. The parts will be supported by 20 x 30 mm L-shaped aluminum profiles. The feet will be 15mm high, 55 mm diameter aluminum pieces (not pictured). The idea is that they will be big enough for them tu directly support the weight of the heat sinks, and what else may be stacked onto these, without the strain being put on the screws and L-profiles.
I still need to find the right place for the extra switch mode PSU and the power / soft start / audio-output-relay switching circuit. also, I bought a pack (200 pcs) of small M3x18 mm screws in black (the hardened ones, but bought for the colour). US$70 !!! Speaking of "getting screwed"!!! (Sorry, moderators, I just couldn't resist it!) We're not talking rare metal screws or anything... just standard industrial screws, for crying out loud! That price is outrageous, but there is only one place around here that sells them 🙁
Jennice
mAJORD,
Nice looking case! Those heatsinks look kind of small to me, at least the fins do. I was wondering about running the fins horizontally. I thought maybe the air flow wouldn't work properly without a fan. I'm looking forward to see how that works out for you. I have seen may heatsinks on ebay with the fins running lengthwise. I would rather run them that way if it works. It would certainly be more comfortable to handle.
Andrew T,
I didn't mean to mislead anyone. The test results I posted are from the add on ebay. I didn't do them myself. Most of them are way over my head. That's why I posted them here so you guys could tem me if this tranny would work for me.
Rod returned my email and said;
The guy I bought the tranny from didn't have a 50V so I bought the 45V. I doubt I will hear the difference between 45V and 50V.
Anyway this is my first project so I expect to have a few hurdles to cross. All in the name of learning. 😀
Jens,
Yeah, I am still learning what all these voltages mean. Once I realized it was going to be over 60V rails I knew it wouldn't work for what I am doing. Too bad since I already promised to pay for it. Now I own a monster toroid.
Hopefully I will find another project to use it on.
The new one I bought should fit the bill nicely.
I'll watch the temperature closely with those heatsinks.
If you really think they are way to small I will look for something else and keep these for a future project. I was thinking that I will probably never run this amp at anywhere near full power for any extended period of time anyway. But I should probably not build it with that in mind.
Blessings, Terry
Nice looking case! Those heatsinks look kind of small to me, at least the fins do. I was wondering about running the fins horizontally. I thought maybe the air flow wouldn't work properly without a fan. I'm looking forward to see how that works out for you. I have seen may heatsinks on ebay with the fins running lengthwise. I would rather run them that way if it works. It would certainly be more comfortable to handle.
Andrew T,
I didn't mean to mislead anyone. The test results I posted are from the add on ebay. I didn't do them myself. Most of them are way over my head. That's why I posted them here so you guys could tem me if this tranny would work for me.
Rod returned my email and said;
The guy I bought the tranny from didn't have a 50V so I bought the 45V. I doubt I will hear the difference between 45V and 50V.
Anyway this is my first project so I expect to have a few hurdles to cross. All in the name of learning. 😀
Jens,
Yeah, I am still learning what all these voltages mean. Once I realized it was going to be over 60V rails I knew it wouldn't work for what I am doing. Too bad since I already promised to pay for it. Now I own a monster toroid.
Hopefully I will find another project to use it on.
The new one I bought should fit the bill nicely.
I'll watch the temperature closely with those heatsinks.
If you really think they are way to small I will look for something else and keep these for a future project. I was thinking that I will probably never run this amp at anywhere near full power for any extended period of time anyway. But I should probably not build it with that in mind.
Blessings, Terry
Terry,
IMHO, your heat sink will be fine for "normal" use with a reasonable amount of bias. Parties, PA use or playing your Electric Bass through it would probably tax it. My 4 channel Leach amp is built on an ApexJr tunnel heat sink with a fan that will turn on if it gets hot. The fan never comes on. But then again, I don't get loud for long.
If you want to play it safe without buying a new heatsink, borrow an idea from my Hafler 500. It has a temperature switch that opens and shuts down the amp if the heat sink gets too hot, and resets as it cools. Digikey has them for about $7, I've seen them for less at allelectronics.com, as surplus house. I'd use something that opens at 60-70C.
Bob
IMHO, your heat sink will be fine for "normal" use with a reasonable amount of bias. Parties, PA use or playing your Electric Bass through it would probably tax it. My 4 channel Leach amp is built on an ApexJr tunnel heat sink with a fan that will turn on if it gets hot. The fan never comes on. But then again, I don't get loud for long.
If you want to play it safe without buying a new heatsink, borrow an idea from my Hafler 500. It has a temperature switch that opens and shuts down the amp if the heat sink gets too hot, and resets as it cools. Digikey has them for about $7, I've seen them for less at allelectronics.com, as surplus house. I'd use something that opens at 60-70C.
Bob
BobEllis & Terry,
I would not go above 60C on the heat sinks (regarding the safety switch).
Also, I would use it to switch the outputs off and/or light an indicator. I would not use it to switch off the entire amp via the mains relay.
Finally, I would use the thermal switch to control a transistor (or similar), as a relay causes nasty voltage spikes when it switches off. I know one does not hope for the thermal switch to operate at all, but it will not keep working if burnt by high voltage arching (sparks) inside it. I've seen this on a car, where a thermal switch on the radiator controlled a relay, which in turn controlled the radiator fan. The relay lived happily ever after, but the thermal switch died every now and then.
Jennice
I would not go above 60C on the heat sinks (regarding the safety switch).
Also, I would use it to switch the outputs off and/or light an indicator. I would not use it to switch off the entire amp via the mains relay.
Finally, I would use the thermal switch to control a transistor (or similar), as a relay causes nasty voltage spikes when it switches off. I know one does not hope for the thermal switch to operate at all, but it will not keep working if burnt by high voltage arching (sparks) inside it. I've seen this on a car, where a thermal switch on the radiator controlled a relay, which in turn controlled the radiator fan. The relay lived happily ever after, but the thermal switch died every now and then.
Jennice
Hi, two thermal switches would be better.
1. to monitor the temp & give a warning.
2. to switch off the amp and latch off.
Why latch? Well without a latch, if the amp is running unattended the outputs will cycle upto cutoff temp and then cool and keep repeating. The transistors that have a high temp range will eventually fail due to this cycling of junction/die/case connection stresses.
regards Andrew T.
1. to monitor the temp & give a warning.
2. to switch off the amp and latch off.
Why latch? Well without a latch, if the amp is running unattended the outputs will cycle upto cutoff temp and then cool and keep repeating. The transistors that have a high temp range will eventually fail due to this cycling of junction/die/case connection stresses.
regards Andrew T.
Andrew,
Apart from the point, that I didn't expect him to run the amp hard, while unattended, you have a very good point there.
Jennice
Apart from the point, that I didn't expect him to run the amp hard, while unattended, you have a very good point there.
Jennice
Jennice:
love the perforated chassis, not only looks good but must be a breeze to attach things to 😀, attahcing various sheilds in my setup is going to be a pain i dont feel like making more swiss cheese, im actually thinking of using existing mounting points as ancors for folded thin alum` sheilds.
as for the opamps, the OPA627 is about the only thing i can get easily, and from what ive read is fairly neutral yet warm sounding, we will see, ive also tried to order some black gate caps for any electros in the signal path. see how it goes.
Terry: cheers, the heatsinks are rated at 0.7deg c /watt. For the low power version (which mine is) 1.0c/watt or lower is recomended by rod, so hopefully these will do the trick, i too was a bit sus about mounting them horizontal, but i will monitor the temps and see how they go. i don't predict any problems tho, being a "fan" type heatsink the fins are quite widley spaced allowing pretty decent airflow regardless, it also gives them good specs for there size as u can see by there rating when compared to bulkier heatsinks.
love the perforated chassis, not only looks good but must be a breeze to attach things to 😀, attahcing various sheilds in my setup is going to be a pain i dont feel like making more swiss cheese, im actually thinking of using existing mounting points as ancors for folded thin alum` sheilds.
as for the opamps, the OPA627 is about the only thing i can get easily, and from what ive read is fairly neutral yet warm sounding, we will see, ive also tried to order some black gate caps for any electros in the signal path. see how it goes.
Terry: cheers, the heatsinks are rated at 0.7deg c /watt. For the low power version (which mine is) 1.0c/watt or lower is recomended by rod, so hopefully these will do the trick, i too was a bit sus about mounting them horizontal, but i will monitor the temps and see how they go. i don't predict any problems tho, being a "fan" type heatsink the fins are quite widley spaced allowing pretty decent airflow regardless, it also gives them good specs for there size as u can see by there rating when compared to bulkier heatsinks.
mAJORD,
The chassis is with 2mm holes, so I can't avoid drilling. I I have a lot of M3 screws around (not only the black ones), as well as locking nuts (those with a thin plastic washer attached, so they won't come loose by vibration or thermal expansion/shinkage.
My plan is to test mount stuff (therefore the line-up), mark and drill the holes, spray paint the metal parts (including the aluminum profiles when I have ut them to length), and then do the final mechanical assembly. I plan on mounting the stuff on the heat sinks, first, though, before mounting these sub-assemblies (2 sinks and the profiles) to the perforated metal sheets and the feet. (The feet screws go through both the metal sheets and the L-profiles, holding it all in place.
After that, I will do the hard-wiring of the remaining electronics (PSU/caps, terminals on the back, etc.)
Jennice
The chassis is with 2mm holes, so I can't avoid drilling. I I have a lot of M3 screws around (not only the black ones), as well as locking nuts (those with a thin plastic washer attached, so they won't come loose by vibration or thermal expansion/shinkage.
My plan is to test mount stuff (therefore the line-up), mark and drill the holes, spray paint the metal parts (including the aluminum profiles when I have ut them to length), and then do the final mechanical assembly. I plan on mounting the stuff on the heat sinks, first, though, before mounting these sub-assemblies (2 sinks and the profiles) to the perforated metal sheets and the feet. (The feet screws go through both the metal sheets and the L-profiles, holding it all in place.
After that, I will do the hard-wiring of the remaining electronics (PSU/caps, terminals on the back, etc.)
Jennice
heh you still have to drill, but uve go a pilot hole! 🙂,
I hate centre taping and drilling, i dont have a drill press, i have to instead be very patient, and make sure drill bits are razor sharp to avoid it running off my centre punch mark
I hate centre taping and drilling, i dont have a drill press, i have to instead be very patient, and make sure drill bits are razor sharp to avoid it running off my centre punch mark
True enough with the pilot hole, but it's a pain if the spacing doesn't fit the things I need to mount.
As for the punch mark, it takes more than a needle, you know. 😉 😀
I use a fairly big nail and a hammer like our friend here:
I'm not suggesting you hammer the nail through, but the drill isn't critical if the punch mark is deep enough.
Jennice
As for the punch mark, it takes more than a needle, you know. 😉 😀
I use a fairly big nail and a hammer like our friend here:
I'm not suggesting you hammer the nail through, but the drill isn't critical if the punch mark is deep enough.
Jennice
I've got another question if you don't mind. I was planning on using a copper plate for the ground strap across the top of the filter caps. I planned to bolt the strap down to the chassis to help hold the caps in place. Is it alright to connect the ground strap to the chassis?
Thanks, Terry
Thanks, Terry
Terry,
It's perfectly OK to bolt the transistor "ground" plate (the - of the positive rail, and the + of the negative rail) to ground. This should then be your only ground reference point. all ground connections from PCB's audio terminals, etc should then meet there.
Do not have more than one ground reference point. If you did, you will cause ground error currents, and they will not be at the exact same location. Also, connecting this single point (well chosen, actually) to the enclosure will prvide the best shielding from RF interference.
Jennice
It's perfectly OK to bolt the transistor "ground" plate (the - of the positive rail, and the + of the negative rail) to ground. This should then be your only ground reference point. all ground connections from PCB's audio terminals, etc should then meet there.
Do not have more than one ground reference point. If you did, you will cause ground error currents, and they will not be at the exact same location. Also, connecting this single point (well chosen, actually) to the enclosure will prvide the best shielding from RF interference.
Jennice
OK, great! I was hoping that would work. I had planned to land all of the ground wires on that strap. Just wasn't sure about tying it into the chassis. I don't have all those neat little cradles for my caps so I figured to sloder them to the ground plate and then bolt the whole works down to the chassis.
My whole reason for building a three channel was to use for the front-end of a 5.1 system for the theater room I'm planning on setting up. I'm hoping it will sound as good as everyone says. If so, I will build a two channel for the rear.
I doubt I will ever run it anywhere near full power but I love the way a powerful amp tends to seperate everything so nicely.
I have a bunch of JBL studio monitors that I plan to use for this.
Blessings, Terry
My whole reason for building a three channel was to use for the front-end of a 5.1 system for the theater room I'm planning on setting up. I'm hoping it will sound as good as everyone says. If so, I will build a two channel for the rear.
I doubt I will ever run it anywhere near full power but I love the way a powerful amp tends to seperate everything so nicely.
I have a bunch of JBL studio monitors that I plan to use for this.
Blessings, Terry
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