My "audiophile" LM3886 approach

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#4,321
atupi said:
Found this interesting link about MyRef Evo : http://www.claudionegro.com/download/articoli/CHF%20116%20Trio%20Solido%20P2.pdf
Click to expand...

Thanks - I've seen the outline schematic before, but not the whole article with pictures. The pics have a lot of additional info relating to the placement and layout which were not obvious before. I used a different routing of the power traces in the MyRef-X2, which wastes a bit of board area but allows the chipamps to be mounted on the edge of the board and simplifies heatsink mounting. It also helps that the MyRef-X2 is a monoblock and completely through-hole.

If I ever respin the MyRef-X2, about the only thing I'd add is the LM317 series-shunt regulator (similar to the MyRef FE).
 
#4,323
Joseph K said:
For Fast Eddie:

I have a maximum respect for this designer. I think he had realized the project what you aim for.

https://drive.google.com/file/d/0BzbIeQI27LjoV21seUw4MG5jQWs/edit?pli=1

Some graphs and pics:

diyaudio.hu • Téma megtekintése - LM3886-QUAD

One day I will give a listen to it, for sure..

Ciao, George
Click to expand...

Thanks. I tried to make it big enough to see, but alas, my eyesight is extremely poor.

It looks like it has some of the ideas I'm working on, but I just can't see it clearly enough to get the big picture.

I have a circuit in mind, where the output chips are nested into the feedback loop on each side of the diff amp. But I'm getting ahead of myself; I need to optimize the single ended amp first, and I have to order some stuff before I can do a physical prototype.

I'm sure that it's been done before. It seems like such an obvious concept.
 
#4,325
Had a look again: i'm able to navigate, zoom in in both google drive links..

Anyway, mzperx, the author is a member here. And the project is definitely worth some considering.
It's a composite totally differential amp, where the bridged/parallel output buffers are encompassed in the outer loop.
the idea might be obvious but a well proven, working realization is very very far from obvious..

So you are onto a great project, wish you all the luck!

Ciao, george
 
#4,326
Yes, I can see it now, thank you.

That is exactly the concept I am thinking of. But first I must parse a practical single ended circuit, order the parts, and then build it. If I am satisfied with it I might move on to build the bridge-parallel.

Right now I am figuring out what I have and what I have to order. One of the links above recommended these bypass capacitors 35SEPF22M+TSS Panasonic Electronic Components | P16407CT-ND | DigiKey for local bypass and after looking at their datasheet I'm going to give them a try. They have much lower high frequency impedance and much higher resonance than comparable electrolytics. It looks like they might be the answer to tantalums, which I have experienced a high failure rate with.
 
#4,329
varun21 said:
What kind of drivers work the best with myref?
Click to expand...

I've used full-rangers, 2-way with 1st-order crossover, 2-way with 2nd-order crossover, and 3-way commercial. They all seem to work pretty well, but it does better with 8-ohm woofers/full-range units. The tweeter impedance doesn't seem to matter much as long as it can be padded to 8-ohms.

For normal listening, I have been using a 6" Sharp driver and a generic Mylar dome tweeter with a 1st-order XO in a sealed enclosure.
 
#4,330
Hi
I m from Kolkata, India. I want to assemble a LM3886 based stereo amplifier system with Bass Treble control. Can someone please suggest good AMP, PSU & BT kit available in India. Do i need any PREAMP if i want to drive it directly from PC or my Mobile?

How about these kits:
1. AMP KIT: Wintek - 68W Mono (LM3886) W/o Heat Sink
2. PSU KIT: Wintek - Dual Rail PSU Module
ALT PSU KIT: Lumin - Dual Rail 150W PSU
3. BT KIT: Wintek - Stereo Tone Control (X-Bass)
ALT BT KIT: Wintek - 3 Way Tone Control
 
#4,331
thekingstallion said:
Hi
I m from Kolkata, India. I want to assemble a LM3886 based stereo amplifier system with Bass Treble control. Can someone please suggest good AMP, PSU & BT kit available in India. Do i need any PREAMP if i want to drive it directly from PC or my Mobile?
Click to expand...

I don't know the specifics of the kits you listed, but the MyRef Rev C monoblocks don't need a pre-amp if driven from almost any PC sound card. From a mobile, you may or may not need a small gain stage to drive a MyRef - it depends on the signal level on the headphone-out jack of the mobile.

I offer monoblock kits for the MyRef Rev C - PM or email me for details if you're interested. It does not however include a bass-treble control, for which you may need an additional board.
 
#4,332
atupi: Thanks. Why is that? What happens if I use low sensitivity drivers? Or is it just that high sensitivity drivers are the in-thing? This will help me make an informed decision.

Siva: It's such a pain to get good drivers here. Which one did you go for? What are my options other than Sharp?

My eyes sparkle at Visaton B 80 though :hypno2:. Coupled with a TIW 300 in a 150L tower. Is it in my stars? :lickface:
 
#4,333
varun21 said:
Siva: It's such a pain to get good drivers here. Which one did you go for? What are my options other than Sharp?
Click to expand...

Of late, not many inexpensive driver options - what I've seen recently are some surplus Panasonic consumer-grade 6" drivers (from Mexico and Brazil), the Sharp 6" driver I mentioned earlier, a Daewoo 5.25" paper-cone woofer and a Robertson Audio 5.25" mid-bass driver that I'm playing around with. The last one seems to prefer a ported enclosure, and is a bit bass-shy, but that's fine with me. I haven't got around to evaluating the Daewoo - it appears to be a close cousin of the Robertson Audio driver (maybe the same OEM in Malaysia or China, just a guess). Of course, the Philips Hi-Q 8" octagonal frame dual-cone driver is still around, if you're into full-rangers. It has limited power handling, but that's not an issue for normal indoor listening.
 
#4,337
What a shame. I had the HQ48001 lying around all the time. They are brand new but I only used them when I was troubleshooting the myref. I also have the Philips Woofers (from the time when Philips manufactured it). I don't know which models though.

So Siva, the laziest thing for me to do is to order MDF towers of around 150L and put these in (or buy HQ48414P). Should I stick the woofers in as well? I plan to go sealed. How many Litres?

Mods: If this is not relevant here please move to a new thread. Thanks.
 

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#4,340
varun21 said:
atupi: Thanks. Why is that? What happens if I use low sensitivity drivers? Or is it just that high sensitivity drivers are the in-thing? This will help me make an informed decision.

Siva: It's such a pain to get good drivers here. Which one did you go for? What are my options other than Sharp?

My eyes sparkle at Visaton B 80 though :hypno2:. Coupled with a TIW 300 in a 150L tower. Is it in my stars? :lickface:
Click to expand...
With low sensitivity speakers You trigger spike protection of lm3886 and this result in very bad sound.
I experienced this with some Spendor sa1 speakers
 
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