Hi Tony, would just like to say I am VERY impressed with your channel, the amount of detail you give and what for me anyway is important, the speed is just right, many thanks for all your efforts and time you give us, simply the best, in your business time is always money so again many many thanks, stay safe and healthy.
I love solder wick, if you bump the heat up a bit I think its hard to beat and the addition of flux helps a lot, I love it when you do a project like this....cheers.
I feel so happy how you reper vintages make me happy 😊 you have sooo many machines to check things original parts . this is not available unfortunately in my contry. if we have any vintage think to reper it is not eazy . most the time no parts . God bless you sir
Hmmmmmmmm, nice job Sir, appreciate the tip on those Green SCRs. High power point to point connection in my ear sounds better than any Digital garbage.
Nice work! Grabbed that tip on the center base parts. Didn't know they existed. Thanks for that. Peace joy and happiness! A tip, I have been experimenting with current regulator diodes for the emitter drive of long tail input pairs in some vintage amps that use a simple bipolar input pair. It has been great so far, but in one instance, I got current injection into ground plane causing hum. All others without a hitch, and the sound has improved allot doing this. A constant current source does wonders here when it works.
I came really close to trying that on this amp. I had a couple of postage-stamp current source modules I made a long time ago with transistors and LED's, but I couldn't find them. Still on my list of things to try. Thanks for the comment!
SuperInteresting to watch and listen when you servicing those audio equipments. Thanks so much Tony. .. ..(here often downloading same schematics to have on the side. Its interesting to learn how those various audio-circuits you are working on are wired/traced, at the same time watching/listening your videos.) _Have nice upcoming weekend. br, from norway.
Tony, re thermal paste, get a thin plastic bag, cut out a small square, fold in two, put over spout, then screw on cap, ,like a condom, then put tube in fridge, lasts longer. This works too with vulcanising solution. Thanks for another grand video....DA. PS, I see Joseph Lalock suggested the same,great minds an all that : )
Always enjoy the "monologue" over the repair as it is moving along. High quality training film in my estimation. Brings me back to my time in field service. Thanks for the look and listen.
Tony, the Tektonix DPO scopes we have at work have an awesome "Filter View" feature on them. We have noise in our lab due to the fluorescent lights (I'm trying to get them to change over to LED). The filter can tune it right out. It is very handy.
My TDS 3032 was $7000 when it was new, and it is just a scope. The MDO has many more features, but for $1600, they had to cut some corners. I love both devices for what they were designed for. No doubt, the Tek scopes are a lot quieter on low voltage scales. Thanks for the comment!
Our Indian friend Central Semicon makes all the difference when working with vintage tht gear :) They often literally make the only replacement option still (commercially) available.
you should try keeping your thermal adhesive in the fridge. a. it would last longer. b. it will thicken when cold so you can keep dripping to a minimum when you need to use it
As per your bit rate comment, I hear what you are saying. That is a very good point. However, as discussed before, when you lay multiple instruments on top of each other, the idea of a sine waves becomes a misnomer. Add in instruments that do not have symmetrical sound waves like a sax or when distortion is intentionally added as in a hard rock guitar and the idea of sampling sine waves is out the door. Once that is understood, it can be more easily understood how more points can more accurately trace a non-sinevwaveform. The issue is that in the recreation d to a process is based on recreating sine waves. That is the point behind my previous comment about us not really knowing how to calculate distortion in the a to d and back process. . All I can say is that my 96 k sample music blows away the 48 K samples music.
You made a comment about not hearing ,01% distortion which sounded like a response to a comment string in the last video. I was not saying you can hear .01% distortion. My comment was related to how each successive gain stage increases any distortion from the previous stage. I was trying to say that the recording medium distortion will be multiplied to a much higher level by the time it is reproduced by the speaker. By that time, the very low levels of distortion may very well be audible. Therefore, keeping distortion low is important and you can't just look at the numbers of each device. The highest levels of distortion happen where energy is changes, mechanical to electrical, digital to analog ( & vice versa) then electrical to mechanical (speakers). Even the best tape decks can have 1% or more distortion. My turntable is stated as having .36% and that is only the arm, not the cartridge We haven't been able to truly figure out how to compare D to A or A to D. I remember recording and playing back a song on my 3 3/4 ips cassette deck. It sounded great. It was all there and sounded the same as the source. Yet something wasn't right. I believe the something was the added distortion of the tape medium. Then the power amp multiplied that cassette distortion as we turned the volume up. The amp was an excellent low distortion amp. So it was not the amp. Even the best reel to reel machines are rated from .5 to 1% distortion. Wireless mics are typically 1% as well. No, you can't hear .01%, but you can hear 1% that has been amplified (multiplied).
One final thing about digital, one of the big issues with digital is bit depth. In order to fit the music on a CD, the bit depth was increased to 6db per bit. That is way too large a difference. Even 1/2 db may be too little. Can you hear 1/2 db? For most, no. But again, when you lay the sound of multiple instruments on of each other ( a chorus comes to mind) this little half db differences would help define this differences and make the music more resolved and more more realistic. That is my theory. Since bit depth is the same for all bit widths, it is only a theory based on years of working both analog and digital, I believe it to be true.
Hi, Tony I am a great fan of your channel, I have 2 RA1412 s and one of them is without outputboards. I will try Chinese KSA50MKII boards (will have to take care of the relai sensing function) but: what substitute would you (iF) take for q606 2sa818 ? Stephan Bulgakov , The Hague, The Netherlands
Working on a DC coupled Sansui G-8700DB monster receiver where if failed catastrophically. All 8 of the TO3 outputs were shorted, and/or open less 3 of them, soft start 3.9 ohm resistor open, many open and damaged resistors on the driver boards. Ordered the ON semiconductor TO3 devices, MJ21193G, and MJ21194G. The driver transistors do not show shorted, but I don't know if I should trust them. 2SC2238B, and 2SA968B, not sure what to cross reference to a new modern part as they are not made anymore. Maybe I should just replace the failed resistors and bring it up slow with current limiting. What would you do?
Can't imagine the quality you'd put in to the field of High-End electronics restoration, of high quality Musical Amplifiers. So many old musical amps out there preferred and used by known musicians and studios. Sorry to say some of the Musical Amplifier service videos I've seen recently are in no-way in-depth.
Yes, if you increase the bit-rate, you have to increase the clock frequency of the DSP, which means more digital noise floating around. Besides, an audio amp isn’t a 2 GHz DSO; you don’t need to reproduce anything much over 20 kHz anyway. 🙂
Digital is executed properly these days. All those issues you mentioned have been dealt with. The only issue is build quality and poor design that introduces noise, something that can happen in the analog world. Digital is great.
Maybe the question has been asked before, which Transistors did you replace. And with what? I have a 1412 with similar problems. (my output Transistors are a mix of different types... These need to be replaced to) Best regards
One question, please, if allowed. At the end of the video, when you play the music, you can see on the VU meters that the left channel is always a bit quieter. Is the cause of the recording or is the left channel really quieter? Thx!
@@keybutnolock There is the same difference in both songs and the camera is aimed almost directly at the VU meter. You can see the differences clearly when you stop the video several times.
@@voenigs612 I have rewatched, both songs are viewed from the left and above, if you look at the perspective on the face of the amp, it clearly gets a lots smaller to the right and bottom. The right VU is being viewed from the left. The meter needles are set away from the meter back. It is a simple adjustment to set the meters to show the same values after setting output values. Why would Tony not do this ? If you watch other videos about amps he has made, you will see he points out the big difference a small difference in viewing angle can make.
@@keybutnolock I cannot accept your reasoning. The camera angle doesn't explain it. I also think Tony does an outstanding job, but in this case he didn't completely do the job. We have different opinions and that's ok!
Hilariously, I listen to everything on cheapish ear buds, or PC speakers, or Bluetooth mini-boomboxes. As long as the music is good, I never notice any of the qualities. If somebody plays a wrong note, though . . .
Too hard to use the desoldering pump when the component leads are bent over. They didn't use snap in components back then as much. Transistors don't anyway.
Why not just use ordinary thermal grease like that on the output transistors? I would think “adhesive”ing it is like putting $2000 brake pads on a beat up old Chevy Tahoe with 200,000 miles on it. Way overkill. And the thermal grease isn’t as runny, either. 😏
The thermal glue bonds the two transistors together, unlike the silicone paste. The paste also has a lower thermal transfer rate than the glue, as it is designed to be an interface between the device and a heatsink. from a cost standpoint, the glue was the same price as good paste, so no savings there. Also, the transistors can't shift around inside the heatshrink (which could be removed after the glue cures. Thanks for the comment! BTW, the glue was only used to bond the diff pair transistors. The outputs still have mica and silicone thermal paste.
@@xraytonyb - It’s good that the adhesive didn’t cost more as I suspect most folks probably are more likely to have thermal paste than thermal adhesive, though I doubt it makes an iota of difference if you’re joining the plastic faces of TO92 case transistors together - the plastic/epoxy case will have way more thermal insulation than either the paste or adhesive. 🙂
Having a lower harmonic distortion is not a good thing for amplifiers 0.1 is better than a lower rating, it's better than what it's spec is I would adjust the feedback so it's 0.1 thd Why don't you have the measurements from your scope on the main screen Paul Daniels does it software The little test you had for the differential pair lot of noise on the transistor can you use a capacitor in the test finding the right value to clean it up should be able to wire it in to the test and keep it matched? I don't like that idea of shrink wrapping the differential pair and with heat sink compound, and then shrink wrap, your trapping in the heat it's not necessary just wrap it with some copper tape don't need any paste Well you could cut the trace and put a surface Mount fuse on the DC that protect the rest of the amp Most important thing in digital is tap rate. Is it resin or Flux? if it's resin you can leave it on the board its less dielectrics then the board itself the resin Have your blood pressure checked you look hypertension take garlic oil capsules 4000MG 4 caplets a day for all your life should be anywhere if you're over 50
Your vintage audio videos are top shelf quality Tony, i watch ALL of them and learn so much! a bIG thank you!!!
Hi Tony, would just like to say I am VERY impressed with your channel, the amount of detail you give and what for me anyway is important, the speed is just right, many thanks for all your efforts and time you give us, simply the best, in your business time is always money so again many many thanks, stay safe and healthy.
i love this format where you show the soldering and replacing the components really enjoyed this thank you awesome video
Looks good, sounds good, and measures well. Can't ask for much better than that.
You are a legend Tony ! Loved this project.
I love solder wick, if you bump the heat up a bit I think its hard to beat and the addition of flux helps a lot, I love it when you do a project like this....cheers.
I feel so happy how you reper vintages make me happy 😊 you have sooo many machines to check things original parts . this is not available unfortunately in my contry. if we have any vintage think to reper it is not eazy . most the time no parts . God bless you sir
I enjoy your projects Tony.
Thank heavens the boards aren’t surface mount, what a nightmare that would be.
I liked the tire/capacitor analogy. Doc BC
Hmmmmmmmm, nice job Sir, appreciate the tip on those Green SCRs. High power point to point connection in my ear sounds better than any Digital garbage.
you are sooo professional person in reper . God bless you 🙏 sir . wish we have someone like you in my contry to reper electricians vintage thinks
Nice work! Grabbed that tip on the center base parts. Didn't know they existed. Thanks for that. Peace joy and happiness! A tip, I have been experimenting with current regulator diodes for the emitter drive of long tail input pairs in some vintage amps that use a simple bipolar input pair. It has been great so far, but in one instance, I got current injection into ground plane causing hum. All others without a hitch, and the sound has improved allot doing this. A constant current source does wonders here when it works.
I came really close to trying that on this amp. I had a couple of postage-stamp current source modules I made a long time ago with transistors and LED's, but I couldn't find them. Still on my list of things to try. Thanks for the comment!
Hi Tony, for the long tabs on the replacement transistors, you could shrink-wrap them to avoid the possibility of shorting out.
One Night In Bangkok, Murray Head.... Nice job, those new transistors sure cleaned things up.
SuperInteresting to watch and listen when you servicing those audio equipments. Thanks so much Tony. ..
..(here often downloading same schematics to have on the side. Its interesting to learn how those various audio-circuits you are working on are wired/traced, at the same time watching/listening your videos.) _Have nice upcoming weekend. br, from norway.
Tony, re thermal paste, get a thin plastic bag, cut out a small square, fold in two, put over spout, then screw on cap, ,like a condom, then put tube in fridge, lasts longer. This works too with vulcanising solution. Thanks for another grand video....DA.
PS, I see Joseph Lalock suggested the same,great minds an all that : )
I am definitely going to do that. I can't wait to hear what my wife says when she finds it in the fridge ;))
@@xraytonyb The joys of living with a man who tinkers with vintage amps : ) Take care mate...DA.
you can never know enough about sodering the flux makes all the difference
thanks for the videos
god clean fun !!
Great information. I have re-capped a few integrated amps and don't always get the results I want.
I enjoy your two cents my man!!!
Came for the troubleshooting ... stayed for the root canal ... 😂
Thank you for the testing/response to component change scenarios. That amp sounds great!
Always enjoy the "monologue" over the repair as it is moving along. High quality training film in my estimation. Brings me back to my time in field service. Thanks for the look and listen.
Tony, the Tektonix DPO scopes we have at work have an awesome "Filter View" feature on them. We have noise in our lab due to the fluorescent lights (I'm trying to get them to change over to LED). The filter can tune it right out. It is very handy.
My TDS 3032 was $7000 when it was new, and it is just a scope. The MDO has many more features, but for $1600, they had to cut some corners. I love both devices for what they were designed for. No doubt, the Tek scopes are a lot quieter on low voltage scales. Thanks for the comment!
Our Indian friend Central Semicon makes all the difference when working with vintage tht gear :)
They often literally make the only replacement option still (commercially) available.
you should try keeping your thermal adhesive in the fridge. a. it would last longer. b. it will thicken when cold so you can keep dripping to a minimum when you need to use it
If you're not transferring a significant amount of heat, just use super glue.
@@NiHaoMike64 no thanks
Good solide amp the way they don't make anymore. I'm into tubeamps but I bet this amp runs very good.
Nice rebuild 👍
Sometimes throwing new parts at an old amp is the best and quickest solution
As per your bit rate comment, I hear what you are saying. That is a very good point. However, as discussed before, when you lay multiple instruments on top of each other, the idea of a sine waves becomes a misnomer. Add in instruments that do not have symmetrical sound waves like a sax or when distortion is intentionally added as in a hard rock guitar and the idea of sampling sine waves is out the door. Once that is understood, it can be more easily understood how more points can more accurately trace a non-sinevwaveform. The issue is that in the recreation d to a process is based on recreating sine waves. That is the point behind my previous comment about us not really knowing how to calculate distortion in the a to d and back process. . All I can say is that my 96 k sample music blows away the 48 K samples music.
Now I have that song stuck in my head.
Great video - as always! BTW, when you first started making videos did your wife ask who you were talking to? :-)
..wondering on that here also :-D :-D
You made a comment about not hearing ,01% distortion which sounded like a response to a comment string in the last video. I was not saying you can hear .01% distortion. My comment was related to how each successive gain stage increases any distortion from the previous stage. I was trying to say that the recording medium distortion will be multiplied to a much higher level by the time it is reproduced by the speaker. By that time, the very low levels of distortion may very well be audible. Therefore, keeping distortion low is important and you can't just look at the numbers of each device. The highest levels of distortion happen where energy is changes, mechanical to electrical, digital to analog ( & vice versa) then electrical to mechanical (speakers). Even the best tape decks can have 1% or more distortion. My turntable is stated as having .36% and that is only the arm, not the cartridge We haven't been able to truly figure out how to compare D to A or A to D. I remember recording and playing back a song on my 3 3/4 ips cassette deck. It sounded great. It was all there and sounded the same as the source. Yet something wasn't right. I believe the something was the added distortion of the tape medium. Then the power amp multiplied that cassette distortion as we turned the volume up. The amp was an excellent low distortion amp. So it was not the amp. Even the best reel to reel machines are rated from .5 to 1% distortion. Wireless mics are typically 1% as well. No, you can't hear .01%, but you can hear 1% that has been amplified (multiplied).
GREAT AMPLIFIER NICE work brother keep up the good work the ital man 🎩👨🎓🏅☝️☻
One final thing about digital, one of the big issues with digital is bit depth. In order to fit the music on a CD, the bit depth was increased to 6db per bit. That is way too large a difference. Even 1/2 db may be too little. Can you hear 1/2 db? For most, no. But again, when you lay the sound of multiple instruments on of each other ( a chorus comes to mind) this little half db differences would help define this differences and make the music more resolved and more more realistic. That is my theory. Since bit depth is the same for all bit widths, it is only a theory based on years of working both analog and digital, I believe it to be true.
Hey Toni, have you done a video on your little circuit for checking the balance of your transistor's?
Check out my series on the pioneer spec 1 preamp. I go into some detail about the matching jig.
Hi, Tony I am a great fan of your channel, I have 2 RA1412 s and one of them is without outputboards. I will try Chinese KSA50MKII boards (will have to take care of the relai sensing function) but: what substitute would you (iF) take for q606 2sa818 ?
Stephan Bulgakov , The Hague, The Netherlands
Working on a DC coupled Sansui G-8700DB monster receiver where if failed catastrophically. All 8 of the TO3 outputs were shorted, and/or open less 3 of them, soft start 3.9 ohm resistor open, many open and damaged resistors on the driver boards. Ordered the ON semiconductor TO3 devices, MJ21193G, and MJ21194G. The driver transistors do not show shorted, but I don't know if I should trust them. 2SC2238B, and 2SA968B, not sure what to cross reference to a new modern part as they are not made anymore. Maybe I should just replace the failed resistors and bring it up slow with current limiting. What would you do?
Can't imagine the quality you'd put in to the field of High-End electronics restoration, of high quality Musical Amplifiers. So many old musical amps out there preferred and used by known musicians and studios. Sorry to say some of the Musical Amplifier service videos I've seen recently are in no-way in-depth.
Yes, if you increase the bit-rate, you have to increase the clock frequency of the DSP, which means more digital noise floating around. Besides, an audio amp isn’t a 2 GHz DSO; you don’t need to reproduce anything much over 20 kHz anyway. 🙂
Tony...I am a dentist, and I'm wondering, if a proctologist is doing a root canal, what is left for me to do?
thanks for the great vids,
Remember last video? Coupling caps can cause phase shifting
Digital is executed properly these days. All those issues you mentioned have been dealt with. The only issue is build quality and poor design that introduces noise, something that can happen in the analog world. Digital is great.
Maybe the question has been asked before, which Transistors did you replace. And with what? I have a 1412 with similar problems. (my output Transistors are a mix of different types... These need to be replaced to)
Best regards
One question, please, if allowed. At the end of the video, when you play the music, you can see on the VU meters that the left channel is always a bit quieter. Is the cause of the recording or is the left channel really quieter? Thx!
Maybe the camera angle, and/or the way it was recorded. It was very short to judge overall balance.
@@keybutnolock There is the same difference in both songs and the camera is aimed almost directly at the VU meter. You can see the differences clearly when you stop the video several times.
@@voenigs612 I have rewatched, both songs are viewed from the left and above, if you look at the perspective on the face of the amp, it clearly gets a lots smaller to the right and bottom. The right VU is being viewed from the left. The meter needles are set away from the meter back. It is a simple adjustment to set the meters to show the same values after setting output values. Why would Tony not do this ? If you watch other videos about amps he has made, you will see he points out the big difference a small difference in viewing angle can make.
@@keybutnolock I cannot accept your reasoning. The camera angle doesn't explain it. I also think Tony does an outstanding job, but in this case he didn't completely do the job. We have different opinions and that's ok!
@@voenigs612 Maybe, I know he's not perfect. Good wishes.
Hilariously, I listen to everything on cheapish ear buds, or PC speakers, or Bluetooth mini-boomboxes. As long as the music is good, I never notice any of the qualities. If somebody plays a wrong note, though . . .
Too hard to use the desoldering pump when the component leads are bent over. They didn't use snap in components back then as much. Transistors don't anyway.
Why not just use ordinary thermal grease like that on the output transistors? I would think “adhesive”ing it is like putting $2000 brake pads on a beat up old Chevy Tahoe with 200,000 miles on it. Way overkill. And the thermal grease isn’t as runny, either. 😏
The thermal glue bonds the two transistors together, unlike the silicone paste. The paste also has a lower thermal transfer rate than the glue, as it is designed to be an interface between the device and a heatsink. from a cost standpoint, the glue was the same price as good paste, so no savings there. Also, the transistors can't shift around inside the heatshrink (which could be removed after the glue cures. Thanks for the comment! BTW, the glue was only used to bond the diff pair transistors. The outputs still have mica and silicone thermal paste.
@@xraytonyb Could you use hot glue to acheive the same effect?
@@xraytonyb - It’s good that the adhesive didn’t cost more as I suspect most folks probably are more likely to have thermal paste than thermal adhesive, though I doubt it makes an iota of difference if you’re joining the plastic faces of TO92 case transistors together - the plastic/epoxy case will have way more thermal insulation than either the paste or adhesive. 🙂
Thanks.
I have two such treasures! unfortunately both are defective!
Having a lower harmonic distortion is not a good thing for amplifiers 0.1 is better than a lower rating, it's better than what it's spec is I would adjust the feedback so it's 0.1 thd
Why don't you have the measurements from your scope on the main screen Paul Daniels does it software
The little test you had for the differential pair lot of noise on the transistor can you use a capacitor in the test finding the right value to clean it up should be able to wire it in to the test and keep it matched?
I don't like that idea of shrink wrapping the differential pair and with heat sink compound, and then shrink wrap, your trapping in the heat it's not necessary just wrap it with some copper tape don't need any paste
Well you could cut the trace and put a surface Mount fuse on the DC that protect the rest of the amp
Most important thing in digital is tap rate.
Is it resin or Flux? if it's resin you can leave it on the board its less dielectrics then the board itself the resin
Have your blood pressure checked you look hypertension take garlic oil capsules 4000MG 4 caplets a day for all your life should be anywhere if you're over 50