I am so glad that you are still working on new projects and posting on your channel! I hope you are doing WELL also! Thank you for your effort and posts! Take care.
1:20 am - the night is but a fetus! Nice to see another nocturnal type - I typically get my second wind around 11:00 pm and go till way later than I should. Always a pleasure watching your stuff!
It is mostly cover up with the paint. Besides, it makes it unique. No other amplifier with have that exact same scratch just in case the amplifier becomes famous in a few hundred years like the Mona Lisa... and becomes worth $millions$ 🙂
I have done that a number of times when using these bell-end transformers and never had an issue but a good gentleman made me think abouit it so it is mounted above chassis just like it came out of the box. I was initially concerned that it would be too difficult to cut the hold perfectly for the outer diameter of the bottom bell to fit but it came out perfectly.
I smiled when you gave the tube socket hole dimensions in fractions! I'm sure some viewers will be thinking WTF? Canada converted to metric when I was about 20 but I was already imprinted to degrees in F, and dimensions in inches, feet and miles. 50 years later, if you tell me it's 15 deg C outside I have to mentally convert that to 59 F to know if I need a jacket or not. I've always found fractional units more intuitive than decimals. One of my early jobs was with a Japanese engineering company. In meetings they could follow me if i said that's half as big as it needs to be but they'd all be reaching for their calculators if I said closer to three eighths! I like your transformer mounting, I'd have probably cheated and used standoffs or a bracket but your way is much more elegant.
"Imprinted"... I like that. Absolutely prefer the fractional measurements. My Greenlee punches are etched, 2 1/2 inches - they are not etched 2.5 inches. That particular caliper is my favorite as it is the only one that is in fractional inches. Love it and will use it to my last breath. On the other hand - I do use, as I assume you do also, metric when it is the established way to do things. No one measures the speed of light in feet/second and ibuprofen is in mg and not ounces, etc. Whatever it takes to get the job done right. Thanks...
I came too late to this party, but I am a firm proponent of controls on the front, ports on the back, and nothing on the sides. Never understood why MacIntosh and others put anything on the side, or why some put the mains switch on the back. You need to be able to rack your equipment, and stuff on the sides prevents that, or at least makes it harder by wasting lateral space. Just my 2c.
Putting input/output and controls on the side had gotten me into trouble also. I like to build on 17" chassis and when mounting that in some 17" racks I built - well - as you said, it doesn't fit. Oh well... I still build left to right as I mentioned in the video and like schematics that have signal flow left to right. Maybe that has something to do with the vintage amplifiers ?
I like very much the asymmetrical style that you have chosen with power transformers on the right instead of placing it between the output Transformers.
Thanks. I do keep the PS and all it components in a corner all to itself. Getting hum into an amplifier with a poor layout is impossible to fix and as I have determined over the years, due primarily to chassis currents flowing from the CT of the power transformer to the electrolytic capacitors. Don't want the signal path anywhere around that area.
It's crazy how different, but still the same, we lay chassis out. I usually keep my power on the left side. Transformer, IEC connector, fuse, and power switch. I have a whole set of Greenlee knockout tools my father left me. I usually keep my volume control where the wiring is shortest. I hate painting chassis also. I get too picky. I end up wet sanding the whole thing because I have a piece of dust or bug in the paint, and putting another coat on. I have considered trying to powdercoat at one time. Still might. Watching for the next video. Want to see the circuit you use. I have a few 807s in my stash.
I painted it last night a got a few minor runs on it. It is still drying in the sun as I write. I can drill holes and work with HV all day long with no issue but If there is any place I can make a mess it is with the paint... 🙂
@ElPasoTubeAmps I'm working on a preamp build right now. I'm using the McIntosh C22 tube circuit. Plus a phono stage. I repurposed an old power supply chassis, but replaced the front and back on it. Used a piece of mirrored stainless on the back. Painted the front but some of it will be wood veneer. Used a Baxandall tube tone circuit. VU meters. Input relays. I'm actually winding a power transformer right now. I got into doing that lately. Maybe I'll make a video of it when I'm finished. I don't make too many.
Good progress. I keep meaning to get one of de-burring tools. Re connectors, completely agree, get the best, same goes for pots. I buy Nuetrik RCA's, bout £6 each & will only use Bournes cermet pots in future. Fed up with new pots going scratchy after a month or so. At low signal amplitude IE line level or lower., you want your signal path to be as good as poss
It is the little things over the years that makes equipment fail - volume pots - AC switches - cheap RCA connectors, etc. can make equipment intermittent and hard to live with. Totally agree with you...
On your power transformer that you are dropping thru the alum Chasse, and bolt the bell covers back on you need to isolate it from the chassie because you will short it to the alum chassis, not from a electral short but from a magnetic flux stand point. Try this take your transformer and short out the bell housing to the E core in the middle of the transformer, apply power to it and with no load to the secondary and look at the current draw . This is apparent power which is wasted p0wer and will decrease your total output power available to you that is why when you take the transformer apart you will have insulating washers to isolate the the bell covers. When shorted you are shorting out the magnetite flux of the transformer causing your current draw witch is wasted. When insulating the transformer back on the chassie make sure to isolate the bell covers from the chassie .Thanks Keith N9QDS
Thanks, Keith. I will have to consider that - never thought about it before and I have done this type of mount a number of times. It does have the wide copper strap around it to reduce external magnetic flux so I am thinking that will take care of it (?). A funny story here - many years ago I wanted to add that magnetic band but wound it around the core and not the outer part of the whole transformer. Immediately when I applied power the transformer moaned and the copper strap came unsoldered. I did a beautiful job putting the strap on but it can't be around just the inner core. I probably had 1 mV flowing with 10,000 amps thru that one-turn loop. I did realize what I had done and laughed - oh well - and of course, took the copper strap off. Thanks for your comments.
I find that metalwork part of building amps very difficult and onerous. I wish I could just 3D print a metal chassis with all the holes for IEC mains connectors etc. 😂
I agree. I have some fun laying it out on the chassis but getting serious with the Dremel tool to cut holes is not something I enjoy. For the round holes I have Greenlee punches so that is not too hard but always have to be care to not create too many "mystery holes".
You want to use parallel push-pull 807? You would need a transformer with a primary Z around 2500 ohms. That is kind of rare. I showed that very UTC transformer in the first video during the visit to my transformer stash but it is not mine to sell or give away. I will keep a watch on Ebay and if I see anything like that I will send you a link. On the other hand... you could use a 5K primary transformer - the most common - and put 8 ohm speakers on the 16 ohm tap and get a reflected Z of 2500 ohms for the 807's. That might not seem ideal but it is acceptable to use OPT with a ratio of 2:1 up or down in impedance (Z). Something to think about.
@@ElPasoTubeAmps That should be pretty perfect in my mind with the cathode bias but you sir would know better than me, I think they say in triode 400v max for 807/1625, I've ran 1625s higher than the 400 limit without any problem.
It is going to be a mono amp - a stereo amplifier is a lot more work and this is more of an experiment project that I can make measurements on and listen to for the sound of the SE design. I find SE amplifiers to have a real charm with the harmonic profile they produce. I don't know if you noticed during the moving of the camera but I use a mono McIntosh MC40 in my shop for FM music. I just parallel the speakers and it sounds great. Stereo has its charm and I have amplifiers that are stereo that I have built but I usually want at least 20 watts per channel for a real listening environment. 20 WPC is a pretty big SE amplifier so not likely to go there.
I don't know how that happened. I can only drag-and-drop the files into the editor. Oh well. We can't edit after published and it would mean deleting this video and all the comments to redo it. Apologies... 🙂
always fun watching you built and explanation of the topology make me more positive in my tube builds
I am so glad that you are still working on new projects and posting on your channel! I hope you are doing WELL also!
Thank you for your effort and posts!
Take care.
Its 03:00 in the Morning and I watch your Video, I am Night-owl too, btw. 1970 I was 5yo :-) Hope you do well & thankyou!
1:20 am - the night is but a fetus! Nice to see another nocturnal type - I typically get my second wind around 11:00 pm and go till way later than I should. Always a pleasure watching your stuff!
You described my schedule quite well. 🙂
Humidity is low for painting in my area of Texas. Don’t worry about that scratch!
It is mostly cover up with the paint. Besides, it makes it unique. No other amplifier with have that exact same scratch just in case the amplifier becomes famous in a few hundred years like the Mona Lisa... and becomes worth $millions$ 🙂
Like the way of mounting the transformer bell housing under the chassis. This should be a nice little amp.
I have done that a number of times when using these bell-end transformers and never had an issue but a good gentleman made me think abouit it so it is mounted above chassis just like it came out of the box. I was initially concerned that it would be too difficult to cut the hold perfectly for the outer diameter of the bottom bell to fit but it came out perfectly.
Also isolate the 4 screws that go to each side of the bell housing from shorting out to the alum housing Thanks Keith N9QDS
I smiled when you gave the tube socket hole dimensions in fractions! I'm sure some viewers will be thinking WTF? Canada converted to metric when I was about 20 but I was already imprinted to degrees in F, and dimensions in inches, feet and miles. 50 years later, if you tell me it's 15 deg C outside I have to mentally convert that to 59 F to know if I need a jacket or not. I've always found fractional units more intuitive than decimals. One of my early jobs was with a Japanese engineering company. In meetings they could follow me if i said that's half as big as it needs to be but they'd all be reaching for their calculators if I said closer to three eighths!
I like your transformer mounting, I'd have probably cheated and used standoffs or a bracket but your way is much more elegant.
"Imprinted"... I like that. Absolutely prefer the fractional measurements. My Greenlee punches are etched, 2 1/2 inches - they are not etched 2.5 inches. That particular caliper is my favorite as it is the only one that is in fractional inches. Love it and will use it to my last breath. On the other hand - I do use, as I assume you do also, metric when it is the established way to do things. No one measures the speed of light in feet/second and ibuprofen is in mg and not ounces, etc. Whatever it takes to get the job done right. Thanks...
I work with architectural dimensions, and I am more used to fractions.
I came too late to this party, but I am a firm proponent of controls on the front, ports on the back, and nothing on the sides. Never understood why MacIntosh and others put anything on the side, or why some put the mains switch on the back. You need to be able to rack your equipment, and stuff on the sides prevents that, or at least makes it harder by wasting lateral space. Just my 2c.
Putting input/output and controls on the side had gotten me into trouble also. I like to build on 17" chassis and when mounting that in some 17" racks I built - well - as you said, it doesn't fit. Oh well... I still build left to right as I mentioned in the video and like schematics that have signal flow left to right. Maybe that has something to do with the vintage amplifiers ?
I like very much the asymmetrical style that you have chosen with power transformers on the right instead of placing it between the output Transformers.
Thanks. I do keep the PS and all it components in a corner all to itself. Getting hum into an amplifier with a poor layout is impossible to fix and as I have determined over the years, due primarily to chassis currents flowing from the CT of the power transformer to the electrolytic capacitors. Don't want the signal path anywhere around that area.
It's crazy how different, but still the same, we lay chassis out. I usually keep my power on the left side. Transformer, IEC connector, fuse, and power switch. I have a whole set of Greenlee knockout tools my father left me. I usually keep my volume control where the wiring is shortest. I hate painting chassis also. I get too picky. I end up wet sanding the whole thing because I have a piece of dust or bug in the paint, and putting another coat on. I have considered trying to powdercoat at one time. Still might. Watching for the next video. Want to see the circuit you use. I have a few 807s in my stash.
I painted it last night a got a few minor runs on it. It is still drying in the sun as I write. I can drill holes and work with HV all day long with no issue but If there is any place I can make a mess it is with the paint... 🙂
@ElPasoTubeAmps I'm working on a preamp build right now. I'm using the McIntosh C22 tube circuit. Plus a phono stage. I repurposed an old power supply chassis, but replaced the front and back on it. Used a piece of mirrored stainless on the back. Painted the front but some of it will be wood veneer. Used a Baxandall tube tone circuit. VU meters. Input relays. I'm actually winding a power transformer right now. I got into doing that lately. Maybe I'll make a video of it when I'm finished. I don't make too many.
Go for powder coating - it works amazingly well in my experience. I got the dual voltage Eastwood kit 15+ years ago and it works a treat.
Good progress. I keep meaning to get one of de-burring tools. Re connectors, completely agree, get the best, same goes for pots. I buy Nuetrik RCA's, bout £6 each & will only use Bournes cermet pots in future. Fed up with new pots going scratchy after a month or so. At low signal amplitude IE line level or lower., you want your signal path to be as good as poss
It is the little things over the years that makes equipment fail - volume pots - AC switches - cheap RCA connectors, etc. can make equipment intermittent and hard to live with. Totally agree with you...
On your power transformer that you are dropping thru the alum Chasse, and bolt the bell covers back on you need to isolate it from the chassie because you will short it to the alum chassis, not from a electral short but from a magnetic flux stand point. Try this take your transformer and short out the bell housing to the E core in the middle of the transformer, apply power to it and with no load to the secondary and look at the current draw . This is apparent power which is wasted p0wer and will decrease your total output power available to you that is why when you take the transformer apart you will have insulating washers to isolate the the bell covers. When shorted you are shorting out the magnetite flux of the transformer causing your current draw witch is wasted. When insulating the transformer back on the chassie make sure to isolate the bell covers from the chassie .Thanks Keith N9QDS
Thanks, Keith. I will have to consider that - never thought about it before and I have done this type of mount a number of times. It does have the wide copper strap around it to reduce external magnetic flux so I am thinking that will take care of it (?). A funny story here - many years ago I wanted to add that magnetic band but wound it around the core and not the outer part of the whole transformer. Immediately when I applied power the transformer moaned and the copper strap came unsoldered. I did a beautiful job putting the strap on but it can't be around just the inner core. I probably had 1 mV flowing with 10,000 amps thru that one-turn loop. I did realize what I had done and laughed - oh well - and of course, took the copper strap off. Thanks for your comments.
I would like to build 807 push pull with 4807 in the output
I find that metalwork part of building amps very difficult and onerous. I wish I could just 3D print a metal chassis with all the holes for IEC mains connectors etc. 😂
I agree. I have some fun laying it out on the chassis but getting serious with the Dremel tool to cut holes is not something I enjoy. For the round holes I have Greenlee punches so that is not too hard but always have to be care to not create too many "mystery holes".
i use Neutrik female rca jacks
Fantastic work. And quick! Is there any way to share what's schematic you'll be working from? Again thank you as always
I will show the two schematics I have to chose from this afternoon or tonight.
@ElPasoTubeAmps thank you, sir.
Can you help me find an output transformer for the 4 -807
You want to use parallel push-pull 807? You would need a transformer with a primary Z around 2500 ohms. That is kind of rare. I showed that very UTC transformer in the first video during the visit to my transformer stash but it is not mine to sell or give away. I will keep a watch on Ebay and if I see anything like that I will send you a link. On the other hand... you could use a 5K primary transformer - the most common - and put 8 ohm speakers on the 16 ohm tap and get a reflected Z of 2500 ohms for the 807's. That might not seem ideal but it is acceptable to use OPT with a ratio of 2:1 up or down in impedance (Z). Something to think about.
Loving the 807 build! I’m guilty of never painting any of my chassis they are all bare aluminum! haha. What B+ are you aiming for?
With the quick measurement I made of the power transformer, I would say the B+ should end up around 425 or so.
@@ElPasoTubeAmps That should be pretty perfect in my mind with the cathode bias but you sir would know better than me, I think they say in triode 400v max for 807/1625, I've ran 1625s higher than the 400 limit without any problem.
Is Switchcraft the connector manufacturer that you use?
Yes - maybe it is age but sometimes names/words just won't come to me. Thanks...
Is this a mono amp? Assumed it was a stereo at first.
It is going to be a mono amp - a stereo amplifier is a lot more work and this is more of an experiment project that I can make measurements on and listen to for the sound of the SE design. I find SE amplifiers to have a real charm with the harmonic profile they produce. I don't know if you noticed during the moving of the camera but I use a mono McIntosh MC40 in my shop for FM music. I just parallel the speakers and it sounds great. Stereo has its charm and I have amplifiers that are stereo that I have built but I usually want at least 20 watts per channel for a real listening environment. 20 WPC is a pretty big SE amplifier so not likely to go there.
Switchcraft?
Yes... thank you.
I'm sure you know already but the video is repeated!
I don't know how that happened. I can only drag-and-drop the files into the editor. Oh well. We can't edit after published and it would mean deleting this video and all the comments to redo it. Apologies... 🙂