My_Ref Fremen Edition - Build thread and tutorial

Good to know there's another group buy going! I'm thinking about 2 more kits for a future active 4-way speaker project. In general, has anyone used the My-Ref in a multi-way project? Any thoughts on that? I'm a little concerned the wattage would be too small for any large woofers. Please re-direct me to the appropriate thread if this info already exists. Thanks!

Tom, Madisonears, has his working with a homemade active crossover last that I knew. I am currently listening to a pair of Linkwitz LXmini's that are powered by 4 FE amps. The LXmini uses a miniDSP for sound correction and the crossovers. It works fine. Although it goes down to 45 Hz, the woofers are pretty small, so I can't answer your question on large woofers. The FE puts out about 45W into 8 ohms, if memory serves, so as long as the woofers aren't too big or inefficient and you don't play too loud, many woofers would be fine. I am using FE's to power 8 inch speakers without any issue.

I guess it depends on the woofer and how deep and loud you want to go.

By the way, if you are curious, the Twisted Pear Sympatico amp is an evolution of the original My_Ref and is claimed to have 100+ watts into 8 ohms. Not the same support or development as here, but similar in concept.

Jac
 
Thanks Dario. I'll leave the MKP's alone for now so I don't risk any damage. And I'll save up for some Z-Foils for R37 eventually. ;)


I should have also mentioned I'm building these with the Evo-A mod as well. Seemed to be the way to go.


Good to know there's another group buy going! I'm thinking about 2 more kits for a future active 4-way speaker project. In general, has anyone used the My-Ref in a multi-way project? Any thoughts on that? I'm a little concerned the wattage would be too small for any large woofers. Please re-direct me to the appropriate thread if this info already exists. Thanks!

Not really the answer but used to power a pair of B&W 801 S2 with a “full” Evolution. This a current hungry beast. The 65 watt Evo with parallel LM3886 drove them to very loud levels. Bass control was excellent.
This was without the A revision. The A revision should do even better.
 
My amps are currently passively line-level high-passed first order at 400hz, so they handle mostly midrange/highs. It is much less intrusive than any active crossover I tried. Previously, the first pair of MyRev C's I built ran my B&W 802's full range. I have never heard any MyRef amp clip, even though sometimes I like to play music VERY loud. They can get slightly congested or compressed at very high volume, but then I back off a bit so as to not disturb the neighbors.

I built a pair of MyRef FE's for a friend who uses them with his Eggleston Andra II's, each of which has two 12" woofers, two 6" midranges, and the Esotar tweeter. He has never gotten the amps to clip, although his listening habits are a bit more subdued. They do not have quite the iron grip on the bass that a larger amp might have (no guarantees there, either), but the bass is clear and musical. He recognizes the very transparent, musical characteristics at all frequencies compared to his previous muscle amp which could be pretty coarse and unrealistic, although he didn't realize it until he heard these. The speakers easily convey the subtle differences between any changes made elsewhere in the system.

For reference, we both attend symphony concerts and he hears plenty of other live music.

You need only a few good watts rather than a lot of bad ones.

Peace,
Tom E
 
My amps are currently passively line-level high-passed first order at 400hz, so they handle mostly midrange/highs.

Peace,
Tom E

Hi Tom,

I had forgotten that you switched to passive. Very interesting.

Just curious, do you use a passive or active crossover for the bass speakers below 400 Hz? I can imagine a high input impedance active crossover for the bass speakers that was simply paralleling a passive crossover feeding the amps for the mid/high speakers. It might simplify things by reducing interaction between high and low filters.
 
Yes, low frequencies are crossed actively to a Class D amp with plenty of grunt. I've not tried a MyRef there, but maybe I should. Seems the bass is not affected by the active circuitry as much as the mids/highs. Perhaps the two are not perfectly integrated, but, after a bit of tweaking, I find the results satisfactory.

Between the 6db passive slope and the midrange drivers' smooth roll-off, I get a second order high pass, which mates well with active second order BW low pass. I think there is a bit of phase mismatch between the two, but I am not sophisticated enough to measure that or do much to adjust it. It is less disruptive at that frequency than it would be higher up. Vocals are generally very clear and present. One can almost understand Mark Knopfler's mumblings. ;)

I tried several opamps in the xover, and the most musical I've heard by far is a discrete from SparkoS Labs. Objectivists scoff at the specifications compared to the little plastic boxes, but they sure sound good and are a nice compliment to these amps. Far too much attention is paid distortion measurements, as if the only thing our ears can detect is THD.

Peace,
Tom E
 
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I'm sure I'll be trying the My-Ref's exclusively in an active multi-way setup at some point. Good to know they can drive your friends Egglestons. Very impressive.


Getting closer on the first two boards. Soldered up the relays and all the rectifiers last night. I only get an hour or so to work each night after the kid goes to bed, so it's slow going. But I'm making progress. :) On to all the electrolytics next, then some chassis work, then transformers!

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[...] the Twisted Pear Sympatico amp is an evolution of the original My_Ref and is claimed to have 100+ watts into 8 ohms. Not the same support or development as here, but similar in concept.
Well, not exactly. It share the use of LM3886 (actually its "double" version, LM4780) inside a nested NFB loop, but similarities stops there.

Its higher power comes from its balanced (bridged) configuration.

OTOH, MyRef/MyEvo concept is quite different and unique with its use of the LM3886 configured as a "current pump".
 
Well, not exactly. It share the use of LM3886 (actually its "double" version, LM4780) inside a nested NFB loop, but similarities stops there.

Its higher power comes from its balanced (bridged) configuration.

OTOH, MyRef/MyEvo concept is quite different and unique with its use of the LM3886 configured as a "current pump".

Fair enough. What I meant was that Russ White of Twisted Pair was the first one to interpret Mauro's My_Ref design into a pcb and the the chip based amps that Twisted Pear has sold have evolved from a variation on the My_Ref experience. You are correct that he has moved to a very different place.

Jac
 
Wired up one of my toroids for a quick test on one board last night. Relay clicked on the first power-up! I guess my soldering skills aren't so bad after all. Also, I was reading .01mV offset on the output. I'm VERY happy with that. Other voltage readings were pretty much on spec except for R101, which is only reading 1.1V. R201 is reading 1.2V. Is this an issue? Also, ground to the LM317 is reading a few volts below 35V, but I would assume this is attributable to the fact that I am using an Antek AS-2222 with 22V secondaries. Let me know if anyone has any thoughts on my voltage measurements. I haven't hooked the amp up to a source or speaker yet.
 
Wired up one of my toroids for a quick test on one board last night. Relay clicked on the first power-up! I guess my soldering skills aren't so bad after all. Also, I was reading .01mV offset on the output. I'm VERY happy with that. Other voltage readings were pretty much on spec except for R101, which is only reading 1.1V. R201 is reading 1.2V. Is this an issue? Also, ground to the LM317 is reading a few volts below 35V, but I would assume this is attributable to the fact that I am using an Antek AS-2222 with 22V secondaries. Let me know if anyone has any thoughts on my voltage measurements. I haven't hooked the amp up to a source or speaker yet.

Congratulations! No smoke and a relay click.

Regarding the voltage across R101, I would check the voltage across C102 and C202. They should be within 1 volt of the +14V/-14V respectively. Also flip over to ACV at the same time and make sure there is very low AC. The difference you are seeing is probably nothing, just component variation in the regulator circuit.

When you are talking about ground to LM317, I assume you mean the voltage across C101 and C202. If that's the case, then yes, with the 22 VAC secondaries and no load, you will probably be around 30V. It will likely drop a bit when you start running current through the amp.

If I were in your shoes, I would wire up an expendable speaker, feed the thing with some sort of volume control of pre-amp, and see if music comes out.

Jac
 
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Thanks for the tip Jac. I tested both boards with a makeshift speaker (Dayton PS95-8) and my phone as the source. They sound fantastic!!! Can't wait to get them playing through some real speakers. Thank you Dario and everyone that contributed to the My_Ref, especially the late Mauro Penasa.
 
A few updates. I'm working on mounting all of the components for the cleanest look possible. Here's why I soldered the Faston terminals to the bottom of the board. I wanted the look of a tube amp's exposed components without all the wire clutter. I'm really happy with the way its coming together so far. All the wires will be concealed below the 1/8" thick aluminum plate. I'll build a wooden frame for the aluminum plate to sit on and recess the input rca's, mains plug, and speaker output terminals into the wood frame.


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Apologies for busting in here, but was hoping you guys might be able to get me back on track...

I ordered qty6 1.7 boards back at the initial group order. At the time I had been following the 1.7 build thread enthusiastically and especially the various componant swaps/trials.

At some point (c Sep 2016) I kind of dropped off the face of the earth, and am now back and interested in sourcing parts and building 6 channels. I plan to follow through the build thread for 1.7 from where I left off, but am really interested in the current evolution of ultimate parts BOM for 1.7 and where to find it.

Again, sorry if I posted this in a < appropriate place (and long in content:eek:)

Everyone have a great and festive Holiday season, and stay safe!

Mark Parshall
from SFO bay area, USA
 
Hey Mark,

Welcome back. Don't feel you are behind the times. I'm about to start building some v1.2 boards I have and will eventually get around to the V1.0. The cool thing is that the circuit hasn't changed, just better implemented and updated BOM.

For a normal build, the Google Drive folder on the first post of this thread takes you to the BOM, etc. The first link has the BOM for version 1.5 and up. The suggested best part columns are what you are looking for.

There are some tweaks. The evo A is a worthwhile tweak and is also shown in the BOM. IF you are confident of your skills and want to try the latest ideas, start reading at about post 3078, page 308. Joseph K has been experimenting with opamps and has found interesting options. Care is needed at each step because you could ruin your amp or speakers, but everyone who has tried them has liked them.

Good luck and enjoy.

Jac