| rudi |
X-Calibre: Hot Rodding Mauro Penasa's LM3886 design
Mauro Penasa designed a very "different" LM3886 amp
http://www.diyaudio.com/forums/show...&threadid=54571
This is a really great sounding amplifier and tweaking it is allot of fun
There has been allot of speculation as to "tweaking" this design and unfortunately it has been shot down several times.
Here is a tweakers board, you can try allot of different configurations on it even build the original design on it, if you want, Minus the bridge rectifier
I will be doing a bit more documentation on it and how to build it,
My design uses
2 x 550VA transformers
8 x 10 000 Sprague 40v caps
16-x MUR 860
And all other caps are Rubycons
Regards
Rudi |
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| rudi |
| PCD - component side |
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| Dr.H |
Rudi, that's what we all want to know!
For the chaps in outer Mongolia to decide to build this after they built Rev C, they need to know that this outperforms previous designs. Also some specs perhaps? |
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| rudi |
Hi Dr.H
I do not want to give Mauro the idea that I am being disrespectful to his intellectual property. But he will have to give us something new because this one (for me at least) is much better. There is no way that I am going back to the old design - this one beat it hands down. in one word CLEAN
Sound staging is wide, while keeping a pinpoint accurate focussing
It has a depth that i did not pick on the original.
The entire sound spectrum cleaned up, bass is tight well defined. mids are sweet and very clean and tops are just spectacular,
The basic specs are the same as the original. i have just changed board features
* Possibility for larger input caps. The big boxy ones normally sound better
* Bipolar feedback cap configuration
* Parallel main caps. - You can get the advantages of more expensive caps by doubling up two caps
* snubber - if you want that. I tried it and it worked well, gave some life back to the amp
* Series or shunt regulation for the LM318 or even both if you want.
* Discrete diodes for the bridge rectifier – MUR 860
for the rest. It is exactly the same as the ref C, the main reason for me making this board available is that I thought that you can really make this amp sing. And that is where Mauro had the vision and I just want to give it the drive, as you can see in essence it still Mauro layout and 90% of his design. I just added the BLING |
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| rudi |
| just realised that we are missing the components |
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| Dr.H |
I've listened to Rudi's X-amp. It is very very good. We are all here to DIY and in that sense I think that Rudi has taken a great design and gotten even more performance out of it.
The sound of X:
Most noticeable was the quietness/blackness of the background, with no noise/hash present.
Extended, detailed and airy highs-lovely to listen to, no hint of grain. This is a real strong point in the amps performance, giving a real sense of musical timing, especially in acoustic jazz feauring cymbal work.
Mids were wonderfully detailed and present in the performance. In one instance, for the first time, I heard voice vibrato on a well-known piece by a female vocalist.
Bass was fundamental, i.e. not rolled off, but deep and powerful. The body of an acoustic/upright bass takes on more flesh/realness than previously.
Staging and presence were reference class.
Shortcomings? The amp needs a good pre to show its best. We started the listening session with a passive ALPS, but the pot tended to some warmth/bloom in the lower mids/upper bass. Replacing with a passive NOBLE cured the problem.
Bottom line is that I was intending to build REVC to replace my 3875-based design. I will now be building X-Calibre, the jump in performance is compelling! |
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| Nordic |
Yeah been talking to Rudi on the phone, actualy had to nag him to post the amp, seeing how there are so many people who are quick to dismiss anything.
I realy like what he did to the amp, although it is certainly no longer a low cost one. Will be one of those multiple month projects for me.
I was in two minds about adding that much capacitance, but Rudi was so convinced and compelling after actualy hearing his amp, there was no containing him.
I look forward to ordering my boards
First we gave you the heart transplant operation, now the x-calibre... proudly souf efrican |
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| carlosfm |
| quote: | Originally posted by rudi
* Possibility for larger input caps. The big boxy ones normally sound better
* Bipolar feedback cap configuration
* Parallel main caps. - You can get the advantages of more expensive caps by doubling up two caps
* snubber - if you want that. I tried it and it worked well, gave some life back to the amp
* Series or shunt regulation for the LM318 or even both if you want.
* Discrete diodes for the bridge rectifier – MUR 860 |
Hi Rudy,
You are obviously in the right direction, and you start to solve some of the issues that made me have absolutely no interest about this amp, it would not perform to the levels I'm used to with my LM3886.
This is not any critics to Mauro, which I respect, but I see this amp since the beginning as an exercise.
There are lots of things to improve there (and still are), but I stepped out of the discussion because:
1. I find the design unappealing. You can do better with less parts.
2. There was some 'animosity' on the other thread against whatever I (and others) said about the design, even if it was a suggestion to help improving it.
Yes, you have better results by snubberizing those big caps.
Yes, you have better results with discrete diodes, and the MUR860s are very good. This was reported years ago by Peter Daniel.
What are you guys doing, sleeping?
We are discussing this for years, working hard and sharing it here and you guys go all the way back and make the same mistakes all over again and then 're-discover' the ways to improve the amp, while this is old story for us that have extensive experience with these chips.
PS: Ryan, listen to the amp with the AD815 pre. ;) |
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| Nordic |
Well, if the alternative is just making the same mistakes and not moving on, then I think this is a step in the right direction...
In Mauro's defence he has always stated that some of the design principles were compromises, ones he was ok with, and also to some extent I'm sure some of these compromises included not haveing to spend as much on components.
There may yet be more elegant soutions as you alude to, but in the mean time us hobby types who didn't have the priviledge to have an electronics education, are haveing fun, learning good fundementals (sometimes the hard way), and most importantly building some decent amps.
| quote: | Yes, you have better results by snubberizing those big caps.
Yes, you have better results with discrete diodes, and the MUR860s are very good. This was reported years ago by Peter Daniel.
What are you guys doing, sleeping?
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Well these weren't in the Mauro amp, and now they are... I would hardly call that sleeping!
Have a good evening. |
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| t. |
Hey Carlos, great to see you on here:cool:
Thanks to Rudi for the new board layout and for opening a tweakers thread for this amp
After all the hype etc for this amp and seeing as though I built both Carlos and Pedja's chipamps why not try this one too, I already have the biggest part of the bits knocking around so I decided to etch the boards and give it a try
I first stook to the RevC parts list etc but used Rudi's layout because of the dual rectifiers which I thought would be better in the long run.
The amp is actually not bad but I was not happy with the bass to be honest
I've always felt Carlos amp had by far the deepest tightest bass out of any of the chip based amps and Pedja's had the best top and sheer clarity, this is MY opinion and in MY system
I now have swapped the standard diodes to MBR10100 Schottkies, removed all the small 100nf decoupling caps off the top board and cut the legs much shorter and soldered them directly to the LM318/LM3886 pins undeneath, the zener for the LM318 has been removed and replaced with seperate diy boards with LM317/337 TL431 set to output +/- 15v, added 2x 470uf back to back low ESR caps in the fb
I prefer the amp already to the original, I will also of course try the snubber too next;)
Thanks again to Mauro for sharing another amp to play with and to Rudi for the layout and fb tweak and to Carlos,Pedja etc for all the advice and nice diy amps to build in the past:D
This will probably be my last chipamp project after a few more mods to this one, I'm going to try the Hpex classD modules next |
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| carlosfm |
| quote: | Originally posted by Nordic
Well these weren't in the Mauro amp, and now they are... I would hardly call that sleeping! |
I hope you haven't taken my post personally, it was not meant to.
But it was funny to see everyone defend this as an untouchable design, and the best chipamp ever (!!!), and defending the (finally admitted) compromises as good, including those that have only one experience with the LM3886 chip: this amp.
I repeat, I respect Mauro (despite his attitude against me since the beginning, I don't know why) and I think this amp was initially created as a pure exercise, he didn't expect it would go on to a commercial offer and so many people building it. |
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| carlosfm |
Rudi, what does 'GECO AUDIO' means?
:confused: |
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| Nordic |
Hey T, couldn't help but notice about the scotkies, (forgive spelling) When I spoke to Rudi yesterday, he mentioned specificaly that he used them, but that they sounded horrible to him, if memory serves correctly, he did like the MUR860 or 680s...
Have you tried those?
Quite frankly the amp is not that bad, in that we are mainly just changeing the power supply circuitry, with the amp basicaly still in basic config. |
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| rudi |
I have had several request for boards or kits.
first of all i will not be able to do any during the december timeframe. sorry guys. it is summer in south africa and evertyhing is closing down during Dec.
I will have to do a investigation to the shipping cost to several countries. the south african postal system is a ripoff and i need to secure delivery if I were to do kits.
the goodnews is that i do have 400 sprague caps available that do add to the performance of the amp
please mail me if you are interrested and i will file all request and act on it during Jan 2006 (which is not that far away) |
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| rudi |
| quote: | Originally posted by Nordic
When I spoke to Rudi yesterday, he mentioned specificaly that he used them, but that they sounded horrible to him, if memory serves correctly, he did like the MUR860 or 680s...
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actually i said that the MBR 10100 gave a very good sound and were very clean but the MUR 860 gives you the bass. most speakers would need this . T. has transmission line speaker and he can sacrifice the bass a bit in order to get more clarity, and the MBR10100 did give me that, it is very nice but robbed the bass a bit |
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| carlosfm |
| quote: | Originally posted by Nordic
Quite frankly the amp is not that bad, in that we are mainly just changeing the power supply circuitry, with the amp basicaly still in basic config. |
Still, the PSU can make a HUGE difference on the sound of the amp. |
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| t. |
| quote: | Originally posted by Nordic
Hey T, couldn't help but notice about the scotkies, (forgive spelling) When I spoke to Rudi yesterday, he mentioned specificaly that he used them, but that they sounded horrible to him, if memory serves correctly, he did like the MUR860 or 680s...
Have you tried those? |
Hi Nordic,
I've tried several including the MUR860 and MSR860, remember this was in my system and my opinion, I personally find the MUR860 to have too much of a sonic signature compared to the schottkies, some people report the schottkies to have no bass and be a bit lifeless but I find them to make the sound less coloured, the Mur860's do seem to add more bass and mids, its down to you if you want this or not:) |
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| Peter Daniel |
| quote: | Originally posted by t.
I've tried several including the MUR860 and MSR860, remember this was in my system and my opinion, I personally find the MUR860 to have too much of a sonic signature compared to the schottkies, some people report the schottkies to have no bass and be a bit lifeless but I find them to make the sound less coloured, the Mur860's do seem to add more bass and mids, its down to you if you want this or not:) |
And what is your reference when you compare those two types of diodes (by saying one adds, the other does not)? |
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| rudi |
| quote: | Originally posted by carlosfm
Rudi, what does 'GECO AUDIO' means?
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Hi Carlos thanks for joining us.
I have lots of little gecko's around our house so i played with the word a bit - so it ended up with a variation of deco and gecko.
see i am actually a architect and i do not know much about the laws of electronics. just how to make them sound better. |
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| Nordic |
I suspect I'm of the bass loving types... my dad was a drummer for 25 years, and one of my my first memories is crawling up and going to sleep on the cushion he packed in the bassdrum bottom to damp it.
Geckos are little lizzards, that can hang on rocks and walls.
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| carlosfm |
| quote: | Originally posted by t.
This will probably be my last chipamp project after a few more mods to this one, I'm going to try the Hypex classD modules next |
Leo, I know you are a 'hardcore' diyer :D and you don't need kits or available PCBs to build something.
Before you go on switching your outputs [joke], give this a try.
I don't know if I'm still on time, you are the one who knows what you wanna do next, but I guarantee you very, very rewarding results. |
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| carlosfm |
| quote: | Originally posted by rudi
I have lots of little gecko's around our house so i played with the word a bit - so it ended up with a variation of deco and gecko. |
But what is a 'gecko'?
What does that mean?
Sorry to bother you with this. :usd:
Edit: I see. Thanks, Nordic. |
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| t. |
| quote: | Originally posted by Peter Daniel
And what is your reference when you compare those two types of diodes (by saying one adds, the other does not)? |
Hi Peter,
In this amp the Mur860's made the bass sound slightly artificial, a bit like cranking the bass up on a graphic eq if that makes sense, it was deeper but became less defined, the high also seemed slightly rolled off (more warm) compared to the schottkies
The MUR860's do seem to work very well with the standard GC amps but they just didn't work well for me in this amp.
Its all personal opinions of course;) |
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| rudi |
| quote: | Originally posted by carlosfm
But what is a 'gecko'?
What does that mean?
Sorry to bother you with this. :usd: |
see the pic that Nordic posted :D |
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| Peter Daniel |
Hi Leo,
I was asking because in a past I was using LM3875 both with baterry supply and AC supply (with MUR860 diodes) and I noticed very little difference in tonality beetween the two.
Battery supply appeared dynamically challenged in a long run and too smooth for my taste. ;) |
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| t. |
| quote: | Originally posted by carlosfm
Leo, I know you are a 'hardcore' diyer :D and you don't need kits or available PCBs to build something.
Before you go on switching your outputs [joke], give this a try.
I don't know if I'm still on time, you are the one who knows what you wanna do next, but I guarantee you very, very rewarding results. |
Thank you Carlos :)
I'd love to try this as soon as I can open it:bawling:
The UCD180's have already been ordered but its something else to try, adding another to my already huge pile of amps won't hurt, its another raved about thing these classd modules so I guess its got to be tried at least |
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| rudi |
t. download them and rename them with a .zip at the end then it works fine
Carlos you hijacker :D - just kidding |
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| t. |
| quote: | Originally posted by Peter Daniel
Hi Leo,
I was asking because in a past I was using LM3875 both with baterry supply and AC supply (with MUR860 diodes) and I noticed very little difference in tonality beetween the two.
Battery supply appeared dynamically challenged in a long run and too smooth for my taste. ;) |
Hi Peter,
Well I've also took your opinions serious regarding conponents especially after trying out the polarity of the BG N caps, I'm still shocked at the noticeable difference it makes;)
Its strange that I didn't like the MUR860's in this amp, maybe its just the design:confused:
I admit to liking the MUR860's probably best with the GC amps though and the Schottkies better if regulators are used |
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| t. |
| quote: | Originally posted by rudi
t. download them and rename them with a .zip at the end then it works fine
Carlos you hijacker :D - just kidding |
Cheers Rudi!
I'll give it a try |
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| rudi |
| quote: | Originally posted by t.
I admit to liking the MUR860's probably best with the GC amps though and the Schottkies better if regulators are used |
T , just somehting that i have noticed. with the X the MBR 10100 were better, and with a snubber evenmore so. but you will let us know when you build yours. it was a compromise because i need to do the entrire spectrum with the amp and for that reason i chose the MUR860
NB: anybody that wants to build the amp with MBR10100 should be aware that you would not have all the bass you are used to. and if you have a small speaker system then the MBR are not recommended. but with a proper fullrange system you will be richly rewarded |
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| t. |
Thats better, nice one Rudi:D
I'll let you know as soon as I can get the new board built, this is going to be a busy month for me:eek:
It goes quite for a while and all these projects come at once
Sorry to go off topic
Thats an interesting looking pre-amp Carlos
I've actually got a couple of those SMD AD815's but never used them for anything yet, I can easily modify your amp and implement the AD815 if I can find my magnifying glass and tweezers
Is there any threads with the layout? I could build this easy enough from your schematic but how did you manage to fit all the parts so close to the chip, its tiny:D
I could cheat and etch a board but no doubt its not as good as a tightly done p2p |
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| carlosfm |
| quote: | Originally posted by t.
Thats better, nice one Rudi:D |
Did you have any problem downloading the file? :confused:
It's a .zip, with 3 .png graphic files inside...
| quote: | Originally posted by t.
Sorry to go off topic
Thats an interesting looking pre-amp Carlos |
That may as well be the preamp of your life.;)
I'm not joking, this is serious.
And you can use it with whatever amp you have.
| quote: | Originally posted by t.
Is there any threads with the layout? I could build this easy enough from your schematic but how did you manage to fit all the parts so close to the chip, its tiny:D
I could cheat and etch a board but no doubt its not as good as a tightly done p2p |
Leo, the chip is not tiny, even the SMD version is quite big and relatively easy to work with.
Look at the datasheet for the pinout of the SMD version.
It has a perfect pinout.
It has the PSU pins located exactly where all the op-amps should, I mean if it was an 8 leg thing that would be pins 4 and 5.
I have never made a PCB for it, although I had the intention (but no time). My prototype (on veroboard) ended up as definitive inside my pre.
Some weeks ago Peter Daniel sent me some non-smd AD815 chips and I made this test setup. |
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| carlosfm |
| This heatsink is very oversized. It doesn't even get warm. |
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| t. |
Hi Carlos,
I could download your file but the pc would not open it, as soon as I added .zip at the end of the file name suggested by Rudi it worked fine
I've just dug out my smd AD815, your right, its not as small as I thought but I know how important the layout is so i'd like to get it right;)
Excellent work from you again and thanks for sharing:cool: I'll have a dig through my parts box, I've been after a nice pre for a while, I've got Nuuks tube pre to try too.
I presume an 8v reg would be ok for the nulling circuit |
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| carlosfm |
| quote: | Originally posted by t.
I presume an 8v reg would be ok for the nulling circuit |
Yes, it's fine. |
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| frdchang |
carlosfm,
i remember you posted the source of your 10k pots...(the green sturdy looking ones in your non soic 815 preamp)
could you post the link again?
i can't seem to find a good 10k pot other than the panasonic ones... (in the US)
thanks, |
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| frdchang |
jaycar double gang log pot
well the green pot is only 5 dollars... (which is better than 20 dollars... at this point in my life)
i will post my 815 preamp implementation shortly. |
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| Dr.H |
| I built this pre sometime ago using CFM's layout. The AD815 is a marvelous pre, easily outperforming the 627/634 combo's. Try it! |
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| rudi |
| Ryan, do you have a spare chip? i would like to try it with the X-calibre. |
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| lazyfly |
Hi Rudi,
If memory serves you were having a clipping issue that was rearing its ugly head with your original rev c. I'm just wondering if that issue has been resolved or you know why it was (is?) happening? |
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| rudi |
Hi Lazyfly.
you will always have those issues with this particular design but it is only when you play very load.
I am checking a few things , but i think that I might have over bias the Lm318 and that is causing the clipping , just a thought. will check it during this week (not that i will remove it if it is a problem, because it makes the amp focus much better)
this is like a race car. to get the max out of it you will have to sacrifice something else |
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| Mick_F |
I'd just like to mention that the Alps RK09 series are very good pots for a very low price. The are sold as 10k and 50k.
Mick |
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| rudi |
here is my current implementation
2 x 550va C-core transformers 28-0-28
8 x 10000uf 40 Sprague caps
16 MUR 860 diodes
rubycon yxf
Wima MKP4 630v input |
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| Mick_F |
| Well.... that looks good! |
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| carlosfm |
| quote: | Originally posted by rudi
you will always have those issues with this particular design but it is only when you play very load. |
There must be some issue on this particular design.
I have 86~87db speakers and a total gain of ~60x (21x power amp + 2.87x pre) and I can't get it to audibly clip, as much loud as I listen to. Maybe I would be deaf before that. |
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| Dr.H |
Rudi and I tested my amp (Pre=AD815 as per CFM, power=NI LM3875, MUR860’s, 300VA per channel, 1000uF per PS leg) against the Excalibur.
Before we get into the detail, Rudi hade made a mod to his DAC (reducing the output cap from 1.5uF to 1.0uF) which I think improved the overall sound of his system-basically the upper bass was not as warm, which I preferred.
Onto the shoot-out:
My amp had highs that were comparable to the X-amp, detailed, extended. This reflects the benefit of the AD815, since on its own, the NIGC 3875 highs tended to be relatively harsh.
That’s were the similarities end unfortunately.
The X-amp had better resolution and separation and presence on the mids. In comparison, my amp sounded a bit congested in the mids.
Also notable was the fact that the X-amp had much better layering, so that the various instruments existed more in their own space rather than being melded into one. But at the same time the amp still sounded organic, i.e. musical.
Bass performance was interesting: My amp went deep (the benefit of the AD815), but not as deep and fundamental as the X-amp-it is a real heavy weight in this department, some of the bass you feel more than hear. Also I’d say that the X-amp was perhaps more detailed.
Overall, the X-amp was more coherent/clean/clear and ultimately musical and enjoyable, especially in the mids vs my own. Less hifi, more music!
I would say that my own 3875 was transformed by the use of the AD815 and Rudi and I will be exploring using it on the X-amp.
Will keep ya’ll posted!
Ryan |
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| rudi |
This has been one of those shoot-outs that had me a bit nervous.
I have heard allot of the Lm3875 and the combination of this with an AD815. To top it Ryan had a DACT CT2 to control all of this
My combination were a passive ALPS and the X-Calibre as is published
The X-Calibre is much more airy and much less hash, much better definition and also allot quieter. the LM3875 sounded closed in and the mids were lifeless. The top were the only part of the amp that sounded realistic.
The LM3875 sounded very much like the stock standard Ref C that i have built (including the 550va trafo's and Sprague caps which transformed the amp) I do not think the commercial Ref-C amp can sound better than the Ref-C I have implemented.
It will be interesting to hear the difference between the standard TP Ref C and the X-Calibre |
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| BrianDonegan |
Rudi-
If I were to build one of these, what component changes to the compensation networks do I need to make to the RevC to handle the altered opamp voltages? |
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| t. |
I finally just fitted the Carlos snubber to this amp (0.47R-1n5) across the LM3886 pins as well as keeping the 100nf
Sorry guys but the snubber does improve this circuit IMO, if you can't hear the difference you must me deaf:D
I tried the MUR860's again but I still prefer the MBR10100
I also fitted the 0.47R-47uf snubber on the outputs of my regulator boards which power the LM318's, the sound has improved some more but not as noticeable as the ones for the LM3886 which is probably because of it helping those big 10k caps
A simple and cheap mod, worth trying at least |
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| rudi |
| quote: | Originally posted by BrianDonegan
Rudi-
If I were to build one of these, what component changes to the compensation networks do I need to make to the RevC to handle the altered opamp voltages? |
Hi Brian. I have done some simulations and the simulations did not show any ill effect with the changed voltages. When I checked it with a scope I also did no find any strange behaviour.
By changing small values on the compensation network is far worse. You will make it unstable in an instant. That is part of the complexity. |
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| lazyfly |
Hi Rudi,
I asked about the clipping because I think I may have crossed its path yesterday. I'll do a little testing today - bypass the pre (which is set to unity anyway) and run passive. I'm using a 50k pot though which may affect this behaviour.
It appears quite a bit earlier (in relation to pot position) than the amp it's replaced which is Brian Bell's 3886 circuit based on Carlos' snubbreed PS. While it could be easy to dismiss the 'volume control level' method as inaccurate (it is) this amp does not go as loud using the same cdp, speakers, cabling etc. Speakers are Peerless 2 way ~89dB, PMt's designed by Rabbitz.
I'll get back to you with some results a little later.
It pains me to say this Rudi but I feel your transformers VA rating is a little low... BAHAHAHA... kidding ;) |
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| carlosfm |
| quote: | Originally posted by Dr.H
Before we get into the detail, Rudi hade made a mod to his DAC (reducing the output cap from 1.5uF to 1.0uF) which I think improved the overall sound of his system-basically the upper bass was not as warm, which I preferred. |
Trying to solve jitter and/or analog stage problems by reducing the output coupling caps?
That's the easy solution, but far from perfect.
| quote: | Originally posted by Dr.H
Rudi and I tested my amp (Pre=AD815 as per CFM, power=NI LM3875, MUR860’s, 300VA per channel, 1000uF per PS leg) against the Excalibur.
...
Onto the shoot-out:
My amp had highs that were comparable to the X-amp, detailed, extended. This reflects the benefit of the AD815, since on its own, the NIGC 3875 highs tended to be relatively harsh.
That’s were the similarities end unfortunately.
The X-amp had better resolution and separation and presence on the mids. In comparison, my amp sounded a bit congested in the mids.
Also notable was the fact that the X-amp had much better layering, so that the various instruments existed more in their own space rather than being melded into one. But at the same time the amp still sounded organic, i.e. musical.
Bass performance was interesting: My amp went deep (the benefit of the AD815), but not as deep and fundamental as the X-amp-it is a real heavy weight in this department, some of the bass you feel more than hear. Also I’d say that the X-amp was perhaps more detailed.
Overall, the X-amp was more coherent/clean/clear and ultimately musical and enjoyable, especially in the mids vs my own. Less hifi, more music!
I would say that my own 3875 was transformed by the use of the AD815 and Rudi and I will be exploring using it on the X-amp.
Will keep ya’ll posted!
Ryan |
Ryan, you are comparing the uncomparable.
Please leave once and for all that low capacitance chipamp. What you are hearing is the amp sweating to drive those speakers. It can sound as soubtle as that, until you hear the REAL THING.
Check the zip file I posted a couple of pages ago.
Follow that strictly and make a new amp, or modify your amp. I prefer the LM3886, anyway, but you will have very good results with the LM3875.
You will wonder from where all that power comes from.
You will also wonder why have you once thought about paralleling chips (which degrades the sound).
And what you will listen, in all aspects, will amaze you.
For unregulated PSU I recommend 20,000uF minimum after the series resistors. I'm using around 30,000uF.
And 2,200uF caps ON the chips, snubberized.
Notice that the amp on this thread is starting to have some similarities to what I've been recommending for the PSU.
Another reason why it also uncomparable the two amps that you listened to?
Because on your amp you are driving the LM3875 chip with a pot or the AD815 pre.
On Mauro's amp (or on the 'X-calibre') you are driving an LM318 op-amp.
You have already built my preamp.
As I know you also are a 'hardcore' diyer :D I'm challenging you to build my amp, strictly following the schematics, as you did for my pre.
:cool: |
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| carlosfm |
| quote: | Originally posted by t.
Sorry guys but the snubber does improve this circuit IMO, if you can't hear the difference you must me deaf:D |
I will not comment, this time. :sour:
| quote: | Originally posted by t.
I tried the MUR860's again but I still prefer the MBR10100 |
It's curious you say that, because I have MBR16100 schottky diodes (3-leg TO-220) on my regulated PSU and I like them very much, but I never tried them on an unregulated PSU. |
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| Panelhead |
I should have time soon to build some amps. The X-Caliber looks very nice. If I tried to compare to the latest CFM NIGC, both should have LM3886 I guess.
OT, but are there any circuit changes needed to use the LM3875 in the latest CFM NIGC? I have a bunch and only one pair of 3886 right now.
I have a pefectly working My_Ref C. It will be interesting to hear it compared to either of these two amps. But my power demands are very low, less than 1 watt at peaks.
George |
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| carlosfm |
| quote: | Originally posted by rudi
The X-Calibre is much more airy and much less hash, much better definition and also allot quieter. the LM3875 sounded closed in and the mids were lifeless. The top were the only part of the amp that sounded realistic. |
Rudi, just look what a power amp with just 1,000uF of PSU capacitance can make for you.
Hash treble is because of the very low filtered PSU and high ripple, and the lower PSRR of the chips at high frequencies.
The rest is the inability of the amp to drive most speakers.
You are on SET territory to match the amp with a pair of speakers. |
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| carlosfm |
| quote: | Originally posted by Panelhead
OT, but are there any circuit changes needed to use the LM3875 in the latest CFM NIGC? I have a bunch and only one pair of 3886 right now. |
No, there are no circuit changes except the fact that the LM3875 has no mute circuit, no ground pin and different pinout. |
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| thejohn |
| OT as well but Carlos, does this mean you prefer your new version of unreg power supply over your regulated one? |
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| rudi |
| quote: | Originally posted by carlosfm
Trying to solve jitter and/or analog stage problems by reducing the output coupling caps?
That's the easy solution, but far from perfect.
|
WHAT?????.......Jitter, my DAC does not have jitter. :D Carlos you just wish you had a DAC like mine. ;)
the Cap is to block 90v DC. and also determines the LF rolloff. so nothing to do with staging and what have you. here you lost it a bit ;)
for the rest. the LM3875 will always suffer, compared to my X-Calibre. the amp is simply the best :D , Ok maybe I am loosing it a bit.
as far as T.'s comments. I will try the snubber today and maybe incorporate it.
Carlos just as a parting word. you are welcome to rant and rave as much as you like here. we will just sit back and grind at your antics :D |
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| rudi |
| quote: | Originally posted by Panelhead
I have a pefectly working My_Ref C. It will be interesting to hear it compared to either of these two amps. But my power demands are very low, less than 1 watt at peaks. |
Hi George. the X-Calibre will have the Ref-C for breakfast , that is just my and Ryan's experience. but I hope for somebody to do a comparison soon of there own.
you can always cannibalise your ref c and use the chips for this one |
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| rudi |
| quote: | Originally posted by thejohn
OT as well but Carlos, does this mean you prefer your new version of unreg power supply over your regulated one? |
Unregulated always sound more musical. But you need to get rid of the ripple to get the bass right. So your only option is a follows
HUGE capacitor banks to smooth the power and a HUGE transformer to drive the poor caps. Then you get very good smoothing. Best of both worlds and the end result is deep clean bass.
That is why I went for 20 000uf per rail 40000uf per channel and 1.1kva transformers and the end result is very evident when you listen to it |
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| rudi |
I have been playing a bit with the amp this afternoon and I discovered a that only the guys that bought the TP version know about the change of resistor values.
R41 and 42 should be 47R instead of 270R, this makes the amp more stable and takes care of the harsh clipping. This was never indicated on the schematics.
I remember somebody asking about it on the original thread.
Seems that the Ref A will be much more stable according to a simulation. I will test the Ref-A version on the X-Calibre and let you know |
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| carlosfm |
| quote: | Originally posted by thejohn
OT as well but Carlos, does this mean you prefer your new version of unreg power supply over your regulated one? |
No, it does not mean that.
I just post the unregulated PSU because it's easier for you to build.
| quote: | Originally posted by rudi
WHAT?????.......Jitter, my DAC does not have jitter. :D |
Wow, that's a hell of a claim.
Rudi, that is not possible, don't believe that marketing BS.
Whatever interface you use, NO JITTER is not possible in digital audio.
| quote: | Originally posted by rudi
Carlos you just wish you had a DAC like mine. ;) |
How do you know???!!!
I don't wish anything.
| quote: | Originally posted by rudi
the Cap is to block 90v DC. and also determines the LF rolloff. so nothing to do with staging and what have you. here you lost it a bit ;) |
What staging???
You're lost, you didn't understand what I said at all.
It's exactly the LF rolloff point that I meant.
With a 1uF output cap, you'll have a high-pass filfer at ~16Hz if you use a 10k volume pot after it, a little on the high side, don't you think?
If you need this to have tighter bass, something else is wrong, you should not need to cut this high.
That's what I meant, take it constructively, and try to improve that.
Please.
| quote: | Originally posted by rudi
Unregulated always sound more musical... |
Rudi, you're making another claim as absolute, and it's not. :att'n:
How can you say always?
| quote: | Originally posted by rudi
...But you need to get rid of the ripple to get the bass right. So your only option is a follows
HUGE capacitor banks to smooth the power and a HUGE transformer to drive the poor caps. Then you get very good smoothing. Best of both worlds and the end result is deep clean bass.
That is why I went for 20 000uf per rail 40000uf per channel and 1.1kva transformers and the end result is very evident when you listen to it |
I don't agree that you need those 1.1kva trafos.
And there's more than 'deep clean bass'. More capacitance is better, and a CRC arrangement still brings improvements. You'll hear clean highs to cry for the cleaner the PSU you use, and low impedance up to very high frequencies.
The regulated PSU I use also provides very 'musical' results (if you want to be subjective to the extreme), ultra-tight and deep bass, gorgeously clean mids and treble. And this with a smaller trafo and lower capacitance.
Please don't make abstract or generic claims, and you also don't have to believe what I say.
You just need to build both and try for yourself. |
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| doggy |
Hi Rudi,greetings
When you can,please let me know about getting 2 pcb's for a stereo pair and also those sprague p.s. caps. I would like to build this version of the Mauro p. amp also. Put me on your list.
I am still learning,and want a good power supply.
I wonder has anyone compared the mur860 diodes to a composite 25 amp rectifier bridge?
Cheers
Doggy :snowman: |
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| rudi |
Hey Carlos
exactly the ranting and raving i was talking about. at least you add flavour to everything ;) |
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| carlosfm |
| quote: | Originally posted by rudi
Hey Carlos
exactly the ranting and raving i was talking about. at least you add flavour to everything ;) |
You tried the snubber, right?
You liked it, right?
Mmmm... maybe I'm not so lunatic as some may think. :D
Why did I say that this amp needed snubbers on those big caps?
Did I even needed to build it and try it?
No.
Why? Because I've been there, done that.
Do you believe me?
Whatever. |
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| lazyfly |
| quote: | Originally posted by carlosfm
You tried the snubber, right?
You liked it, right?
Mmmm... maybe I'm not so lunatic as some may think. :D
Whatever. |
Wait, which amp are we talking about here, Rudi's new 'version' or the original revisions? There were mixed results with the original if memory serves. Yeah I know, try it before commenting, so I'm not commenting on whether it enhances anything, just which version of the amp we're talking about.
Carlos, even if your deemed a lunatic no one can take your passion away so you'd be a passionate lunatic ;)
Cheers
Kendal |
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| DcibeL |
I don't really understand all this talk about whether the subber should be there or not. Everyone has their own tastes, and the parts for the snubber aren't expensive or anything so what's the harm in trying it out and listening for yourself and deciding what you like best. I don't believe there is any right or wrong here, just personal preference. Why should we as a group have to come to a conclusion of what is better. It's your amp, do what you like with it.
Good work on your X-calibre amplifier Rudi. I really like the idea of a regulated supply for the op-amps. I see you've gone with a single relay for each channel. Is there any reason to do this instead of a double pole relay (is that the right term)? Or was it just easier to design the PCB this way? |
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| carlosfm |
| quote: | Originally posted by lazyfly
Wait, which amp are we talking about here, Rudi's new 'version' or the original revisions? |
I'm talking about my experience with these chips, I've done and tested many things with them.
| quote: | Originally posted by lazyfly
There were mixed results with the original if memory serves. |
Nobody tested my last PSUs with this amp. It would not be practical, anyway.
| quote: | Originally posted by lazyfly
Carlos, even if your deemed a lunatic no one can take your passion away so you'd be a passionate lunatic ;) |
Ok, then. :cool: |
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| rudi |
Well there seems to be sour grapes in the twisted pear camp.
Well let’s put some explanations and some apologies were it is due
1. Mauro. Not for one moment did I claim the amp design as my own. I have always given you credit for the schematic and the ingenious thought of implementation. And I thank you for you that
2. Hot Roding is a term to personalize something to your own tastes. In most case upping power or performance. In this case making a different power supply stage
3. My reference to this being commercial. From the beginning Russ stated that they are not doing it for a profit. I own my own business and not for one moment did the math indicate a profit. The point I am trying to make is that there only seem to be help to the people that build the TP version and it is ONLY about the TP version and if there is a small variation there were no support for this.
4. The X-Calibre is my development just as the current TP Ref C is a Russ White development, (by the sound of it with help from Mauro.), But I did mention that it is done according to Mauro design. Again giving him credit for the Amp part of the design.
5. There have been a lot of questions regarding the tweaking of this amp and I just wanted to satisfy the curiosity, and it actually worked. And it works extremely well.
6. The amp that I have originally implemented does clip, I started of by just mentioning it and there were no help to solve the problem or just a speculation of possible problem. If it were a TP board there would have been A LOT defence and immediate help. So the question is why does it clip so harshly when it gets to its limits. The reality is that I have a 9m x 6.5m x 3.2m listening room. It takes a lot of power to fill that room. And the ref-c is most probably not the amp to fill this space. I am already looking a locally amp that will give me 250w and can drive to 1.2 ohm, so no fear in me pursuing this variation, I will keep it strictly DIY. Just as a matter of interest. I tested the X last night and it got to 56W at 8ohm, then it became totally unstable, not just the normal clipping, I did not test it into 4 ohm
To bring me to the public apology.
Guys I am very sorry that I have pushed Mauro over the edge and robbed you of your new amp project.
I am sorry if I have offended anybody with any of my wild statement. I is my personality to get people to take initiative and to push them a bit
I am sorry if I took a condemning tone. It was uncalled for.
The TP is most probably a fantastic amp and I have never compared it to a X so to say that it will eat if for breakfast is very unfair. But it has been done in innocent competitive spirit.
Lets face the facts.
Musical fidelity came up with the topology. Then Mauro adapted it and implemented a more technical version by removing the mosfets and replacing them with a Lm3886 and documenting it in a fantastic way, I took that again and just implemented some known practices on the power supply. |
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| rudi |
| quote: | Originally posted by carlosfm
You tried the snubber, right?
You liked it, right?
Mmmm... maybe I'm not so lunatic as some may think. :D
Why did I say that this amp needed snubbers on those big caps?
Did I even needed to build it and try it?
No.
Why? Because I've been there, done that.
Do you believe me?
Whatever. |
Hi Carlos. I have tried them according to your latest supply and it does give it alot more life.
very much worth the little effort that it took to implement |
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| rudi |
After an unfortunate debate I am withdrawing my efforts from this forum out of respect for the designer. I did not realise that even to post the design i needed his permision
Feel free to contact me directly if you want my view regarding this alternative layout.
My personal opinion is that it sounds extremely good. the layout as is, does work and i have 2 of these running
If anybody would like to make the tweakers board available you have my full permission to do so but please ask Mauro if he has any objections
The Sprague caps that i had available, i will sell wholesale. |
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| float |
I for one am disappointed this little development has caused such a ruckus.
Ironically it was Rudi's enthusiasm for Mauro's amp that made me take the plunge - and I'm glad I did.
I hope you can still post your opinions of any mods you make to the basic design - even if they aren't improvements;) |
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| odysseybmx414 |
| i would just like to say something and that is if i came up with a design and someone else made it better, called it something else and said their modded version of my amp could eat the unmodded version for breakfast i wouldnt take so much offense i would probly build the modded version for having better sound and thank the modder for posting the mods but thats just me |
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| t. |
| quote: | Originally posted by odysseybmx414
i would just like to say something and that is if i came up with a design and someone else made it better, called it something else and said their modded version of my amp could eat the unmodded version for breakfast i wouldnt take so much offense i would probly build the modded version for having better sound and thank the modder for posting the mods but thats just me |
My thoughts exactly mate!
This is a diyaudio forum, its such a shame when the interesting threads end up in arguments, the reason we come here is to share out findings etc |
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| BrianDonegan |
Hi guys-
For the record, I don't mind, and I don't think Russ minds (buy I do not speak for him) that Rudi made his own boards. I also don't mind that anyone wants to try and tweak/change/whatever the circuit, be it on our boards, Rudi's boards or their own. That is why we are all here. I try stuff with mine all the time. That is DIY.
My interpretation of Mauro's comments is that he would like to see more technical discussion/description/reasoning behind mods. I personally do not have the technical depth and expertise to always explain things, nor to comment/remark on other people's. This is why I have not said much or tried to "help out" with Rudi's experiments, not that I mind them, I just don't feel comfortable offering advice I can't justify (plus, I don't have much time to keep up with it all ;) ).
In retrospect (20/20 hindsight), I think we shoudl have broken off the TPA board offering stuff from Mauro's main thread long ago, so that Russ and I could have commented on our stuff without it looking like we were somehow inflexible and hostile to other's ideas. I can only assure you that we are not, though, through the magic of the internet, communication of emotion is generally terrible.
I actually have to run to make some lunch for my son, so I hope this came out okay, as I had to rush it a bit.
I hope we can just get back to playing now ad have some fun! |
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| t. |
| quote: | Originally posted by BrianDonegan
Hi guys-
For the record, I don't mind, and I don't think Russ minds (buy I do not speak for him) that Rudi made his own boards. I also don't mind that anyone wants to try and tweak/change/whatever the circuit, be it on our boards, Rudi's boards or their own. That is why we are all here. I try stuff with mine all the time. That is DIY.
My interpretation of Mauro's comments is that he would like to see more technical discussion/description/reasoning behind mods. I personally do not have the technical depth and expertise to always explain things, nor to comment/remark on other people's. This is why I have not said much or tried to "help out" with Rudi's experiments, not that I mind them, I just don't feel comfortable offering advice I can't justify (plus, I don't have much time to keep up with it all ;) ).
In retrospect (20/20 hindsight), I think we shoudl have broken off the TPA board offering stuff from Mauro's main thread long ago, so that Russ and I could have commented on our stuff without it looking like we were somehow inflexible and hostile to other's ideas. I can only assure you that we are not, though, through the magic of the internet, communication of emotion is generally terrible.
I actually have to run to make some lunch for my son, so I hope this came out okay, as I had to rush it a bit.
I hope we can just get back to playing now ad have some fun! |
It came out fine Brian:)
I've got to know some very nice,helpful and intelligent people on this forum but it is very hard for everybody to agree with this stuff, theres nothing wrong in having debates but it usually does get out of hand.
Well it is nice to see things are calming down a bit now and hopefully both Rudi and Mauro don't leave |
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| odysseybmx414 |
| i was wondering if the "rev c" type design could be used on an opa541 chip as i really love these chips and wondering to make them even better than they already are. |
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| Ed Lafontaine |
| quote: | | i was wondering if the "rev c" type design could be used on an opa541 chip as i really love these chips and wondering to make them even better than they already are. |
Certainly you may try it. However the LM318 was chosen for its characteristics within the circuit that is Mauro's Ref. It is a synergistic relationship that is unlikely to duplicated or bettered by another opamp. This is explained better by Mauro himself in his thread. I don't want to discourage you from trying any option. I think however, if you would read the "high points" of Mauro's thread, you would understand this better than I can explain.
If you try it, we would surely like to know how it turns out.;) |
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| mikelm |
I think - more to the point the op amp that Mauro uses has some extra active pins that he utalises in the Rev C version.
So it's unlikely that other op amps will be substitutable...:(
rev A is more flexible...:) |
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| t. |
OPA541 is a power op-amp like the LM3886, I would not recommend you fit this with the Mauro circuit
You could probably build the amp around this chip but alot of circuitry needs to be changed |
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| mikelm |
| whoops - wrong chip...:xeye: |
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| carlosfm |
| quote: | Originally posted by BrianDonegan
My interpretation of Mauro's comments is that he would like to see more technical discussion/description/reasoning behind mods. |
No, here's what he said:
| quote: | Originally posted by mauropenasa
Compliments, Rudi. I wish you much success, with the results of MY work.
I Want you remember that you have not the legal right to criticize Russ or other if sell Kits.
I Want you remember that you are using the fruit of MY work, not of YOURS. |
This doesn't need 'interpretation'.
Mauro has the right to act this way, it's his design.
I may not agree with lots of attitudes you guys have taken with those who suggested improvements, but I respect these ownership issues.
So, love it or leave it.
What doesn't mean that people can't discuss improvements to the amp, on another thread.
Like... this one. :D
For those who have interest to improve this amp.
I don't.
It doesn't appeal to me at all, sorry. |
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| BrianDonegan |
Hi Carlos-
I wasn't referring to that comment in particular. That one is directly between Mauro and Rudi and is not my business. I agree it needs no interpretation.
I was speaking more of his general comments regarding critisism of the design. |
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| carlosfm |
| quote: | Originally posted by BrianDonegan
I was speaking more of his general comments regarding critisism of the design. |
I didn't see real criticisms of the design, that's on your head, as well as Mauro's.
What I saw was people suggesting improvements, or putting their hands on it and making it theirselves. That's what Rudi did, and I don't see any problem about it.
Think about it, if people make changes and go to that trouble is because they see the amp as promising, or as a good basis for a good amp.
I don't see what's wrong with that.
I think Mauro takes things too personally.
Mauro, if you're reading this, come on, let people build your amp, improve it, whatever. It will always be your amp. |
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| BrianDonegan |
Ah. I don't mean critisism as a negative term. I mean it as design comments. Like literary critisism. As in suggested changes and improvements.
Once again, I think we are agreeing, but don't know it. ;) |
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| Russ White |
| quote: | Originally posted by carlosfm
Mauro, if you're reading this, come on, let people build your amp, improve it, whatever. It will always be your amp. |
I don't think Mauro has any issues with any of that. :) Its just that if you are going to claim an improvement, it should be with a healthy dose of realism and respect.
Just and when someone claimed to "improve" your "snubber" and you were offended. :) |
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| ron.eddy |
I am a newbie to this whole forum, as can be seen from my registered date on the left. I have read the entire thread about the Mauro amp (myself wanting to build it), which is an excrutiatingly (sp?) long thread, and I have also read all of the branch off threads including the TP sections, and now this whole thread (a refreshingly light length so far!)
With that said I honestly (from an outsiders point of view completely) do not understand what all of this is about. Mauro posted a very unique design and many people liked it and built it. He posted it on a Do-It-Yourself website with no confidentiality agreement or anything like that (patents, etc...). This means, legally, people are free to make modifications, etc to his circuit and post those modifications. Once something is disclosed, it is unfortunately very hard to protect the rights of the one who made it, since it was disclosed in a public forum (i.e. public knowledge). In fact, here in the United States, there is virtually NO protection for public domain ideas (as far as I know). Unfortunate, yes, but good for the DIY crowd, for sure! We wouldnt exist without these rules (other countries vary of course).
That leaves us with only one way to protect it - respect. From all of the posts I have read and all of the threads, I can't think of a single instance of anybody ever disrespecting Mauro or his design or the "compromises" he made in building it (for cost reasons or whatever). In fact, quite the opposite I have seen. People have shown the utmost respect with the design (TP, Rudi, Carlos). They suggested improvements, and sometimes things got a little tense, which it seems was usually out of misunderstanding...
Insults were thrown around a little, but it seems to me like it was all over nothing. In the end we have to all go by what the original designer has to say about it, but lets face facts here, Mauro has admitted to not being the best at English, so when he says things in type, the "magic of the internet" and its inability to convey proper emotions is even worse. I am quite positive from reading Mauro's responses that he never meant to insult anyone or anything, nor is he overly concerned of people modding his designs (as can be seen in the quote Carlos gave from Mauro to Rudi), yet because of his less than ideal English, his sentences do come out as blunt and direct, causing aggression in many of the people on these threads, and that is very understandable, given that its a text conversation. Does he want to keep being recognized for the base design? Of course! And that just all goes back to respect. Which as I said I feel everyone has exhibited, even if at times things got a little heated.
I am new to the DIY audio scene and when I came to this forum I could not wipe the smile off my face. Here after all my searching was a place where I could interact with others who share my interest in the electrical world. I was so happy to join, and so happy once my moderator hold was lifted (after a few posts ;) ). It seemed like a great community for shared works, idea presentation, and helpful advice. But reading threads like these and seeing how things can get blown so far out of proportion makes me sick. It honestly kills some of the vast amount of enthusiasm I had for DIY audio, and makes me wonder whether this is where I want to spend my time learning about it all. And oviously that is what we are all here for.
So, in short, we can all get along just fine with common sense, and as far as I have seen from the 2000 or so posts I've read on this topic, there is a TON of common sense to go around.
Keep up the good work all of you. Mauro for the design, TP for the propagation, Rudi, Carlos, anyone else for the mods. Just be sure to know where it all came from - All of you, on diyaudio.com :D
Just an outsider's opinion, take it with a grain of salt of course. Sorry for the long post. I hope I came off alright, I mean NO disrespect to anyone. You all know more than I can even imagine and I look up to all of you. ;) |
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| Nordic |
Nice post.....
Now, can we posibly keep the rest of this thread for the actual discussion of the x-Calibre Mauro amp.
I still full intend building one, and reporting back!, may not be quickly though due to cost and parts aquiring processes...
So.... ! There are those of us who would like to see the thread go on. Just notice how Rudi is not posting lateley, same as Mauro.
Its just all this arguing and aruing about arguing and whether we have the right to do so etc... this site is not a physcology paper, lets get back to it being hands on, DIY and real.
Rudi, bring it on! |
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| carlosfm |
| quote: | Originally posted by Russ White
Just and when someone claimed to "improve" your "snubber" and you were offended. :) |
Russ, I was not offended, where did you see that?
What I don't accept is someone that says he can't detect any improvement by using snubbers on his LM3886 amp claiming an 'improvement' of something he doesn't even understand and he doesn't even admit.
And then he uses his own values.
His site has snubbers all over it, he has a link on his footer with incorrect information.
His 'improved' snubber is only on his head, because it's really no improvement, he doesn't understand it to know what he is doing.
He is using snubbers always with the same values, and in different places, even after regulators.
The snubbers had became a disease for him, I have been followed and attacked since the beginning by P-A.
Maybe he has seen some gold mine on this, I don't know. (???!)
Well, he sees $$$$ on everything, and I don't care what he says or what he does.
Whatever.
I simply let him say it say it's an improvement.
Who cares?
Not me.
He is happy that way. |
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| Russ White |
| quote: | Originally posted by carlosfm
What I don't accept is someone that says he can't detect any improvement by using snubbers on his LM3886 amp claiming an 'improvement' of something he doesn't even understand and he doesn't even admit.
And then he uses his own values.
His site has snubbers all over it, he has a link on his footer with incorrect information.
His 'improved' snubber is only on his head, because it's really no improvement, he doesn't understand it to know what he is doing.
He is using snubbers always with the same values, and in different places, even after regulators.
The snubbers had became a disease for him, I have been followed and attacked since the beginning by P-A.
Maybe he has seen some gold mine on this, I don't know. (???!)
Well, he sees $$$$ on everything, and I don't care what he says or what he does.
Whatever. |
Carlos,
Your statements right there are precisely what I think Mauro was feeling. People who do not really understand the circuit claiming to "eat for lunch" the implementation of someone who does. :)
BTW I do think your RC network (I wish it had a better name then snubber which is not correct) in the PS does indeed help almost all common NS chipamps. But success is very dependant on the amp design itself, which in the case of the "My Ref" is so much more than the LM3886, and very much different than a standard chipamp. You cannot apply the same rules to it as you could a NIGC and expect simillar results. Just because it uses a LM3886 does not mean all the same factors apply at all. The "snubber" mod is not one which can be universally apply to all topologies, at least not without some alteration. The "Snubber" must change to suite the circuit/trafo/PS to be truly useful. :) So there is no possible way one single set of snubber values will work universally unless all else is constant. That will never occur.
Carlos, I have always been very keen to listen to you as I know you clearly know what you are talking about. I have a lot of respect for you. It is too bad you don't think the "My Ref" is worth building, as if you tried it I think you would have a very different opinion, and you may be able to provide more detailed insights for those of us who value and respect your talents. And perhaps you could suggest things based on measurements and experience with the real thing, and not just supposition.
I would be more inclined to give your comments more weight if I actually thought you had something at stake. Something like your very own amplifier. :)
It would be great to see you contribute in a form more substantial than an outsider's words, not that that is not generous of you to post, it is, but I would love to see more. :)
So, I think you and Mauro feel a lot alike about your respective work. Keep in mind that from what Rudi said Rudi intended to sell the amp, which if he was not respecting the wishes of the amp's creator is not a good thing to do, just as you might feel about your work being improperly used by others. I am sure Rudi and Mauro have mended fences by now, and I am not bothered by Rudi in the least, in fact I think he just simply made a mistake in judgment which has long been forgiven. It really has no impact on me in the least.
I am just another happy DIYer who mods as much (probably much more) as the next guy. For instance I have tried your RC nets ("Snubber") on the "MyREF" long before it was ever suggested by anyone on the threads, but my findings were not (and have never been after trying all sorts of revisions) positive, and so I asked the designer "why did it not sound better, but worse?" then I learned that the LM3886 in the bridge/current pump configuration is quite another beast from a gainclone or an ordinary chipamp, and also learned of the issues of the ringing supply. But, because I respect those who know better than me I treat my findings with the skepticism they deserve as should we all until we are certain our findings are truly valid. :) So I have not really said "yes the snubber works in this case" or "no it does not" all I can say is "that guy who designed the amp tells me no it does not help, and could hurt" which was born out in my tests as the amp did not sound as good with those mods in place.
So, no acrymony here, no desire to squelch creativity or new ideas. Just an admonition to those with an open mind to use due dilligence in research, and not to buy too much into the latest "fads" or amplifier buzzword. In the end the person responsible for execution is the "Do it Yourselfer" not the designer. So many amps end up something completely other than what the creator created, but who is to say if it is "better" or "worse", really anyone who wants to can report anything they like. People can and do say whatever they like in a public forum. :) People can build whatever they like, and I will be very happy for them, but don't expect me to buy into a reported mod without a healthy dose of skeptisism - since I know what the amp is capable of in its stock configuation it will be very hard indeed to sell me on any "huge" improvement. ;)
For what it is worth, I have deigned more than a couple amps based on the "My Ref" design using many major and not-so-major design changes.
Here are a few:
1) Active shunt regulators for the bridge PS (much better than the 78xx-79xx regs). Almost no effect I can detect. Which is to say it still sounds ecellent. :)
2) A single chip LM4780 stereo version of REV A which uses AD8610s and sounds very good indeed. :yes: but better? well who is to say? Sure, I like it a lot, but I am not going to say it eats anything for lunch. I may only like it because it is(at least to some degree) the fruit of my labor, so of course I am biased, so I treat my own opinion as just that, an opinion, not fact.
3) Fully discrete amp modules using a bridge board and a power board and seperate PS. This is the most flexible appproach to the amplifier as it allows all sorts of tweaking since it is completely modular. :) This version I will likely eventually share, but I will work with Mauro and others to perfect it (as if anything is ever perfected) first.
These works I have done largely on my own, but I have gotten a lot of intellectual help from many here on the forum, not the least of which is Mauro himself. So, it should be obvioius to all I am all for "improving" and making the design my own, but I know my own limits, and I measure my words.
Sorry for the very long post, but I just didn't want anyone to think modding the "My Ref" amp is anything new, or that people don't do it or have not been doing it. It has been done from the beginning well before most DIYers could even obtain a PCB. Now at least they have something to play with. BTW it is very easy to mod TP monoblocs, just email me if you want to know how to try something. I will not discourage anyone, but I am not affraid to say "been there, done that" either, because while I have not tried everything I certianly have tried a lot of the mods proposed, and my experiences are sometimes quite different from what a few have reported. That is fine, but it is a fact everyone should consider. The phrase "your milage may vary" is key.
So happy building/modding/listening persue you happiness in the ways that please you best.
Cheers!
Russ |
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| rudi |
1- Mauro and myself did make peace and all I can say he is a true gentleman
2- just to be clear on a matter. My intension was to give 10 boards away for free. I am not into making up kits seeing that I have my own business to run and that is generating more than enough income.
3- all of us have different systems and some better some worse so how do we know what would sound good in another man's system. if you have small speakers, the amp will be limited, and if you have full range you will hear a bit more of what the amp can do.
the amp needs a system that can do 35hz -> up, changes will be more revealing on larger full range speakers than on smaller speakers seeing that the bass affect everything once you add it into the equation.
4-regarding the snubbers, well that is very simple for some it works and they can hear the difference and some don't in the X if added more life..........very simple but in other systems it might detract from the sound. The best is to find the point were you are happy and leave it like that, it most probably not last long before you change something.
5- the X works better in my system than the previous board that I build. And it is now stable without any clipping what so ever. I am getting 56W into 8Ohm. I am actually thinking of asking Mauro how to reduce the gain.
This is a fun project, and if i had to design amps or variations for a living I would have been bankrupt by now. So guys. Lets move on and build some really hot stuff. |
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| carlosfm |
| quote: | Originally posted by Russ White
BTW I do think your RC network (I wish it had a better name then snubber which is not correct) in the PS does indeed help almost all common NS chipamps. But success is very dependant on the amp design itself, which in the case of the "My Ref" is so much more than the LM3886, and very much different than a standard chipamp. You cannot apply the same rules to it as you could a NIGC and expect simillar results. Just because it uses a LM3886 does not mean all the same factors apply at all. The "snubber" mod is not one which can be universally apply to all topologies, at least not without some alteration. The "Snubber" must change to suit |
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