Without a circuit its impossible to say what everything does. You could look up the device number of the chips and see what they are.
I think its going to be really really easy to make a mess of this and end up ruining it (my opinion).
I think its going to be really really easy to make a mess of this and end up ruining it (my opinion).
Agree with Mooly. The components used are of good quality and more than sufficient, and it seems there is no capacitor in the signal path, I don't think by changing the resistors/capacitors will yield any noticeable benefits, even if you use Duelund cap. You might just ruin the tidy look and degrade the sound.
IMHO, the only component that can be replaced are the 2 NE5534 opamps in the preamp section (if I remember correctly), you may replace it with top opamps, like OPA627, AD797, etc.
IMHO, the only component that can be replaced are the 2 NE5534 opamps in the preamp section (if I remember correctly), you may replace it with top opamps, like OPA627, AD797, etc.
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Looking at the voltage rating of the main filter caps, the main supply lines are around, or above +/-50V DC, so the 100V Schottky diodes you mentioned are not suitable for this application. One type I used successfully in my modding practice is BYW 29-150 and 200, those are ultrafast 8A rectifiers in TO-220B case.
The other thing to replace -where you will hear the difference for sure- is the main filter caps, with Kendeils, but they are not cheap. In my opinion those are the best filter caps for audio use.
The other thing to replace -where you will hear the difference for sure- is the main filter caps, with Kendeils, but they are not cheap. In my opinion those are the best filter caps for audio use.
Modifying audio equipment: recommended components
Very good site about recommended parts for audio mods. (mostly for Naim stuff, but I guess useful for others too....)
Very good site about recommended parts for audio mods. (mostly for Naim stuff, but I guess useful for others too....)
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Thank you for all your replies. So are all of the Wima 0.1uf caps in the power supply and none in the signal path? I was planning on changing the filter caps from Nippon 10000uf to Mundorf MLytic AG 15000uf and changing the little blue Epcos 0.01uf bypass caps with Mundorf Evo-Oil 0.01uf poly caps. The On Semiconductor MUR420 diodes are rated at 4A 100V, could I swap these for Cree SIC Schottky 6A 600V diodes?
The MUR420 are ultrafast 4A 200V rectifiers, changing those to anything "better" is only waste of money, and won't cause any audible difference .... IMO
Sorry I meant 200V. I have read that Schottky diodes are more 'quiet' than their ultrafast counterparts. From a technical standpoint, would it be possible to replace them with 6A 600V Cree SIC Schottky diodes? They only cost a few dollars each so I wouldn't mind the small outlay to reduce the noise level even if it's almost negligible.
Been looking up op amps and it seems the opa627 is the best. Please can someone advise whether I can definitely change the NE5534 op amp for this? I found opa627 op amps on eBay for £4.75 each but I would rather pay £25 from here and know they are real! OPA627BP TEXAS INSTRUMENTS, Operational Amplifier, Single, 16 MHz, 1 Amplifier, 55 V/µs, ± 4.5V to ± 18V, DIP, 8 Pins | Farnell element14
Never buy semiconductors like opamps from ebay. Ask yourself why the price seems to good to be true.
You can not just go swapping in devices like the OPA627 without at least having the circuit in front of you. Its a high performance device and needs care in designing and using the appropriate circuitry.
http://www.diyaudio.com/forums/anal...u-have-checked-see-its-stable-havent-you.html
You can not just go swapping in devices like the OPA627 without at least having the circuit in front of you. Its a high performance device and needs care in designing and using the appropriate circuitry.
http://www.diyaudio.com/forums/anal...u-have-checked-see-its-stable-havent-you.html
Mmm, it is really starting to sink in just how unsimple upgrading something is. It is so far beyond my knowledge it's scary! I honestly thought it was a just a case of swapping out parts for better parts but that's far from the case. So far the only thing that I am sure about changing are the filter caps. Is this a safe place to start?
You mean the reservoir caps... the two big ones ?
From an electrical point of view of not doing any harm its a safe place. One real issue that I don't think has been mentioned is that it takes considerable skill and experience to desolder and cleanly remove components from a board like this. Its all to easy to chew up the print removing parts without the correct equipment.
From an electrical point of view of not doing any harm its a safe place. One real issue that I don't think has been mentioned is that it takes considerable skill and experience to desolder and cleanly remove components from a board like this. Its all to easy to chew up the print removing parts without the correct equipment.
I really wouldn't bother trying to upgrade this amp. Seems they got most things correct in the first place and the design of the amp doesn't really lend itself to upgrading easily nor are you likely to get any significant upgrade in sound quality. I say this as someone who likes to replace caps etc with better specced parts but you do have to choose your 'battles'.
My advice would be to sell the amp and move up the range if you are generally happy with the SIM Audio sound.
Something I have learned since reading forums is never to trust the guesswork, exaggeration and scuttlebutt we read everywhere on audio chat forums and blogs. I think that many folk are probably sincere and actually have performed their claimed modifications, perhaps correctly too, but we still cannot assume their conclusions are more than BS or just imagination saying there is any improvement to be had there amongst the endless part swapping.
Much enthusiasm to tinker comes from the hubris of audio gurus or those who just like to see others take them at their word. This is a social game too. Tests though, should include some note of our imperfect hearing and the gaps that are often filled by psychological influences like expectancy, mood, programme affinity and the delays between samples. Are other neutral observers happy with the result or just happy that you are? Is it just one or all changes in a number of parts swaps?
Modifications can take hours, days or weeks to complete. After only short delays, movement etc. there is no way you can expect memory to work for you as a reliable reference for minor perceptual changes. Suppose the sound was considered worse or "dunno" by another listener? Who is correct? Was this a waste time?
We can learn much here from the professionals over years but we won't have understood much by reading a datasheet or a few forum threads and then claiming that because B has better specifications than C that it is significant to an audio application. What of the dozens of other parts not yet tried by either guy or the fact that "tried" is meaningless without controlled testing. This is where we need to know a lot more than forum chat before messing with quality designs. Because they are not just another slapped-together piece of me-too budget electronics, Moon amps are one of the last places to begin tinkering IMV.
If you would like to start learning audio electronics with recommended texts and tinker with parts for different sound effects, we can often help. After the audio electronics basics, you could buy a cheap kit of power amplifier parts, build and test, listen and enjoy. Consider the design and parts values - simulate what occurs when dumb things are done to the circuit. Then progress to a known good but old working amplifier model and experiment, backed with the knowledge and care gained from something inexpensive, simpler and easier to understand. Who knows, you might prefer the sound of simplicity.
Down the track, you might find that the design and build DIY theme here has a lot to offer everyone. You may want to share your own DIY efforts with others here too. That could be worth striving for 😉
Much enthusiasm to tinker comes from the hubris of audio gurus or those who just like to see others take them at their word. This is a social game too. Tests though, should include some note of our imperfect hearing and the gaps that are often filled by psychological influences like expectancy, mood, programme affinity and the delays between samples. Are other neutral observers happy with the result or just happy that you are? Is it just one or all changes in a number of parts swaps?
Modifications can take hours, days or weeks to complete. After only short delays, movement etc. there is no way you can expect memory to work for you as a reliable reference for minor perceptual changes. Suppose the sound was considered worse or "dunno" by another listener? Who is correct? Was this a waste time?
We can learn much here from the professionals over years but we won't have understood much by reading a datasheet or a few forum threads and then claiming that because B has better specifications than C that it is significant to an audio application. What of the dozens of other parts not yet tried by either guy or the fact that "tried" is meaningless without controlled testing. This is where we need to know a lot more than forum chat before messing with quality designs. Because they are not just another slapped-together piece of me-too budget electronics, Moon amps are one of the last places to begin tinkering IMV.
If you would like to start learning audio electronics with recommended texts and tinker with parts for different sound effects, we can often help. After the audio electronics basics, you could buy a cheap kit of power amplifier parts, build and test, listen and enjoy. Consider the design and parts values - simulate what occurs when dumb things are done to the circuit. Then progress to a known good but old working amplifier model and experiment, backed with the knowledge and care gained from something inexpensive, simpler and easier to understand. Who knows, you might prefer the sound of simplicity.
Down the track, you might find that the design and build DIY theme here has a lot to offer everyone. You may want to share your own DIY efforts with others here too. That could be worth striving for 😉
Thanks your message Ian, I am in the process of looking for a compete book on electronics and trying to learn as much as I can. Hopefully one day I will be able to give advice rather than just seeking it.
In an ideal world I would sell it and buy a better model but the price jump is crazy! They become very expensive and so I was hoping to improve things a little with some tweaks. The only reason for this is that I notice that the sound can become a little hard a high volumes, it's not the speakers as I have had them for years and know their sound even at much higher volumes. I will not be doing the work myself, I will get getting a professional to do it who specialises in upgrading units but generally they are source units or DACs and amplifiers rarely get requested. So I was trying to get as much knowledge from experienced guys like yourselves to help as much a possible. If you could copy and paste the questions below and write your opinion on each I would really appreciate it very much.
Changing the Wima MKS2 polyester 0.01 caps to something that may offer better performance. Any thoughts?
Please can anyone tell me if there are any resistors in the signal path and if so, changing these to Ohmite Audio Gold 5W versions? Any thoughts?
The potentiometer is a motorised 50KBX2. I am looking into changing this into TKD 2CP-2511 MC Motorized. Any thoughts?
Changing the preamp opamps from NE5534 to OPA627BP so long as the voltage is ok and it does not cause any oscillations. Any thoughts?
Changing the main reservoir caps from Nippon 10000uf to Mundorf MLytic AG 15000uf. Any thoughts?
Changing the smaller reservoir cap from a Nichicon 2200uf to a Mundorf MLytic 2200uf. Any thoughts?
Changing the Epcos Polyester 0.01uf bypass caps on the above reservoir caps to something that may offer better performance. Any thoughts?
Changing the On Semiconductor ultra fast 4A 200V diodes to Cree 6A 600V Schottky diodes. Any thoughts?
Snubbering either of the above diode options with either or both a 0.1uf cap and a 200K resistor. Any thoughts?
I know I have asked a lot of questions and thank you to those that have already answered some of my questions. I thought I would write a full list as I wanted to cover all potential upgrade options. I would be very grateful for your thoughts and advice on all the above options. Many thanks in advance. 👍😁👍
Changing the Wima MKS2 polyester 0.01 caps to something that may offer better performance. Any thoughts?
Please can anyone tell me if there are any resistors in the signal path and if so, changing these to Ohmite Audio Gold 5W versions? Any thoughts?
The potentiometer is a motorised 50KBX2. I am looking into changing this into TKD 2CP-2511 MC Motorized. Any thoughts?
Changing the preamp opamps from NE5534 to OPA627BP so long as the voltage is ok and it does not cause any oscillations. Any thoughts?
Changing the main reservoir caps from Nippon 10000uf to Mundorf MLytic AG 15000uf. Any thoughts?
Changing the smaller reservoir cap from a Nichicon 2200uf to a Mundorf MLytic 2200uf. Any thoughts?
Changing the Epcos Polyester 0.01uf bypass caps on the above reservoir caps to something that may offer better performance. Any thoughts?
Changing the On Semiconductor ultra fast 4A 200V diodes to Cree 6A 600V Schottky diodes. Any thoughts?
Snubbering either of the above diode options with either or both a 0.1uf cap and a 200K resistor. Any thoughts?
I know I have asked a lot of questions and thank you to those that have already answered some of my questions. I thought I would write a full list as I wanted to cover all potential upgrade options. I would be very grateful for your thoughts and advice on all the above options. Many thanks in advance. 👍😁👍
Here's the latest edition of a widely used and respected text: https://www.amazon.co.uk/Art-Electronics-Paul-Horowitz/dp/0521809266
Not cheap but a better investment than throwing gold plated parts into an already high-end amplifier.
If you want to recap your amplifier and replace the motorised pot for some reason, your replacement may not be a drop-in component or the diode snubbing components may require fixings to install properly, though snubbing each diode is an outdated and incorrect means of quelling the increased switching noise of fast diodes. Get a technician to do the work since you would be very unwise to attempt modifications without first having experience with hand SMT solder assembly.
Don't try it on real commercial products until you've built something similar yourself. There is a lot to learn and a lot of practice to achieve the skill and confidence needed. You can try and maybe succeed too but what you will have after that will not fetch its value any more. It will be seen as a damaged item, not an upgraded one unfortunately. There will be tears if you hoped amateur upgrades would be all wine and roses. Sadly, they are not often so.
I don't have much to say on changing caps. I've used M-lytics only 7 or 8 times and not happily because of price and a few disappointments. Sometimes the claimed qualities of components don't mean they will do anything that any other replacement cap of the same spec won't also do in the same location. Caps are like tyres - any new tyre beats a well worn one. If we don't compare when both types are new, how can we claim either as superior?
Not cheap but a better investment than throwing gold plated parts into an already high-end amplifier.
If you want to recap your amplifier and replace the motorised pot for some reason, your replacement may not be a drop-in component or the diode snubbing components may require fixings to install properly, though snubbing each diode is an outdated and incorrect means of quelling the increased switching noise of fast diodes. Get a technician to do the work since you would be very unwise to attempt modifications without first having experience with hand SMT solder assembly.
Don't try it on real commercial products until you've built something similar yourself. There is a lot to learn and a lot of practice to achieve the skill and confidence needed. You can try and maybe succeed too but what you will have after that will not fetch its value any more. It will be seen as a damaged item, not an upgraded one unfortunately. There will be tears if you hoped amateur upgrades would be all wine and roses. Sadly, they are not often so.
I don't have much to say on changing caps. I've used M-lytics only 7 or 8 times and not happily because of price and a few disappointments. Sometimes the claimed qualities of components don't mean they will do anything that any other replacement cap of the same spec won't also do in the same location. Caps are like tyres - any new tyre beats a well worn one. If we don't compare when both types are new, how can we claim either as superior?
Thanks Ian for the book link and for your thoughts.
Redline why do you recommmend the OPA627AU instead of the OPA627BP?
Redline why do you recommmend the OPA627AU instead of the OPA627BP?
It's usually complex with SMDs and if you don't have access to the schematics or at least a report by someone who's already performed some mods.
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