It may indicate a revision of the original, not compliant to Mauro's guidelines
It was the original name of the Fremen Edition, Mauro asked to change it, same as above.
Mauro sold last PCBs some years ago...
It may, one day, produce some more but from what we know it's out of production.
In that case, if there is no financial harm or direct competition to the designer/manufacturer of a non-production item, no patents or registered trademarks are violated, and full attribution is given as a courtesy, we may be swinging at windmills. As I said, my preference would be to depart from all "My Anything" as a naming convention and just make a clean break. I don't remember seeing "Edison" on the last bunch of incandescent bulbs I bought. 
If others feel differently, please post your reasoning.
If others feel differently, please post your reasoning.
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My Ref Tradeoffs
I'm new to the My Ref world. I've been reading lots of threads and I've got a couple of questions for you My Ref experts. Forgive me if these have already been covered and I haven't gotten to them yet.
I understand the uniqueness of this design and the recommendations of 24 VAC for 8 ohm and 22 VAC for 4 ohm loads. I've got a couple of kits on order from Siva and those will work fine with my current speakers.
My first question is how do you decide how much current you need from the transformer with this design. I usually assume a power rating, figure the voltage required working back from the speaker, and then calculate the current needed based on the power and voltage. In the My Ref, the voltage is defined by the design or so it seems. Do I use the same approach while watching that I don't exceed the maximum current of the 3886? I'm curious because I seen people using everything from 100 to 600 VA transformers for these amps and I don't understand why the variation.
That brings me to my second question. What are the tradeoffs or limitations of the My Ref design relative to lower impedance speakers? I understand that Rev A or C can drive 4 ohms without problem, but there appears to be an issue below 4 ohm load. Is this a limitation of driving a lower impedance at high power or a limitation for any drive level? I ask because I am considering using My Ref for a future speaker project with individual monoblocks for each driver. The tweeter on this project is the B-G Neo3 planar tweeter. I presents a nearly constant 3 ohms to the amp. Because it is a high sensitivity speaker and only covering the high frequency portion of the music, it doesn't require high voltage or power, but it is still a low impedance. Is the My Ref a poor choice for such a speaker?
Thank you in advance for helping me understand.
Jac
I'm new to the My Ref world. I've been reading lots of threads and I've got a couple of questions for you My Ref experts. Forgive me if these have already been covered and I haven't gotten to them yet.
I understand the uniqueness of this design and the recommendations of 24 VAC for 8 ohm and 22 VAC for 4 ohm loads. I've got a couple of kits on order from Siva and those will work fine with my current speakers.
My first question is how do you decide how much current you need from the transformer with this design. I usually assume a power rating, figure the voltage required working back from the speaker, and then calculate the current needed based on the power and voltage. In the My Ref, the voltage is defined by the design or so it seems. Do I use the same approach while watching that I don't exceed the maximum current of the 3886? I'm curious because I seen people using everything from 100 to 600 VA transformers for these amps and I don't understand why the variation.
That brings me to my second question. What are the tradeoffs or limitations of the My Ref design relative to lower impedance speakers? I understand that Rev A or C can drive 4 ohms without problem, but there appears to be an issue below 4 ohm load. Is this a limitation of driving a lower impedance at high power or a limitation for any drive level? I ask because I am considering using My Ref for a future speaker project with individual monoblocks for each driver. The tweeter on this project is the B-G Neo3 planar tweeter. I presents a nearly constant 3 ohms to the amp. Because it is a high sensitivity speaker and only covering the high frequency portion of the music, it doesn't require high voltage or power, but it is still a low impedance. Is the My Ref a poor choice for such a speaker?
Thank you in advance for helping me understand.
Jac
Welcome to the MyRef world.
The mids/tweets I am running right now on MyRefC monoblocks are crossed actively 2nd order at 300Hz. Their impedance dips down to 3 ohms at 300Hz, and below 2.5 ohms at 5k; the rest is around 4 to 6 ohms. I don't know how much power I'm using, but probably not much as I don't listen at ear-splitting levels. I have pretty hefty heatsinks (compared to the size of the chips) and they never get more than warm. The chips have never "spiked" and don't get more than barely hot (able to touch without any painful reaction). Each amp has a 22v, 200VA transformer.
I ran these same amps full range into B&W 802's, which are 8 ohms nominal. I think they dipped down to just below 6 ohms. Never had a problem, even when fully cranked.
I think thermal management is important for these amps. Use a pound or so of well-finned, well-coupled aluminum per chip, and they'll play all day.
Peace,
Tom E
The mids/tweets I am running right now on MyRefC monoblocks are crossed actively 2nd order at 300Hz. Their impedance dips down to 3 ohms at 300Hz, and below 2.5 ohms at 5k; the rest is around 4 to 6 ohms. I don't know how much power I'm using, but probably not much as I don't listen at ear-splitting levels. I have pretty hefty heatsinks (compared to the size of the chips) and they never get more than warm. The chips have never "spiked" and don't get more than barely hot (able to touch without any painful reaction). Each amp has a 22v, 200VA transformer.
I ran these same amps full range into B&W 802's, which are 8 ohms nominal. I think they dipped down to just below 6 ohms. Never had a problem, even when fully cranked.
I think thermal management is important for these amps. Use a pound or so of well-finned, well-coupled aluminum per chip, and they'll play all day.
Peace,
Tom E
Thanks
Tom,
Thanks for that. It helps me understand that, as unusual as aspects of this design are, the basic sizing of transformers works like I've always done. I don't have my mind completely around what is going on in a My Ref but I'm looking forward to giving them a try.
Thanks again.
Jac
Tom,
Thanks for that. It helps me understand that, as unusual as aspects of this design are, the basic sizing of transformers works like I've always done. I don't have my mind completely around what is going on in a My Ref but I'm looking forward to giving them a try.
Thanks again.
Jac
Are you using the same pot you were using before?
Use Caddock MP930s (remember the clip-on heatsink on them) for the current setting resistors.
I was referring to DCB1's parts...
BTW a 10K pot would probably be better.
A good quality low price pot (much better than the Alps) is the Type 21 SMD attenuator you can find on ebay.
They were the caps included in the original BOM.
They sound good and full but not as refined as Silver Micas.
330pF??? Where?