Hi Adrian,
As I recall, the mica sounded flat, not bad, just not as alive. The ceramic, a MLCC COG, was also uninteresting and a bit harsh. The polystyrene, or is styroflex?, was warmer without being colored. In the normal, 150 pF used for other opamps including LM318, I usually use an Amtrans AMCH or some old styroflex ERO caps I have, so it makes sense that something like that would work here. The cap has a similar impact on sound as with the 150 pF. It just needs to be a smaller value for stability.
I have been using the quad SMD R3 until recently. I had a stability problem that turned out to be outside of the FE, but I removed them and replaced them with Isabellenhutte to see if it helped. Both sound good, but there was no point in removing the IH R3's. I have some of the quads running in another project amp, so I still find them interesting.
Jac
Regarding C32 at 68 pF for OPA828, these might be interesting. I haven' tried them, but they would be another option.
https://www.newark.com/wima/fkp2o100681d00jssd/film-capacitor-68pf-1-kv-5-radial/dp/74M1161
https://uk.farnell.com/wima/fkp2o100681d00jssd/cap-68pf-1-kv-5-pp-through-hole/dp/1519291
Jac
https://www.newark.com/wima/fkp2o100681d00jssd/film-capacitor-68pf-1-kv-5-radial/dp/74M1161
https://uk.farnell.com/wima/fkp2o100681d00jssd/cap-68pf-1-kv-5-pp-through-hole/dp/1519291
Jac
Thanks George, it was needed.
If you don't mind I've included it (with credits and minor editing, see chapter 13) on the preliminary updated build guide.
George,
I do not have the IsabellenHutte yet. Next build.
I have a parallel - series combo of Dale Current sense resistors in one build and Caddock in another.
Hi Dario / fellow members ...
New to this forum - Dario, there seemed to be numerous threads about your My-Ref Fremen and I couldn't see one that was still actually current, so I sent you a PM yesterday evening.
However, I've now found this thread this morning which does indeed seem to be very current and active!
So, my question to you was 'are your kits still available' - which looking through this thread I can possibly deduce that indeed they are! In which case, I would love to obtain a kit and would appreciate if you could confirm the current arrangements for doing so (order on latest 'Group Buy' form?).
Also, is the current BOM list (v1.5 and up) still the recommended one to obtain best sound?
Many thanks indeed,
Richard
New to this forum - Dario, there seemed to be numerous threads about your My-Ref Fremen and I couldn't see one that was still actually current, so I sent you a PM yesterday evening.
However, I've now found this thread this morning which does indeed seem to be very current and active!
So, my question to you was 'are your kits still available' - which looking through this thread I can possibly deduce that indeed they are! In which case, I would love to obtain a kit and would appreciate if you could confirm the current arrangements for doing so (order on latest 'Group Buy' form?).
Also, is the current BOM list (v1.5 and up) still the recommended one to obtain best sound?
Many thanks indeed,
Richard
Pm Dario, see if he has any boards left.
Best parts on Dario's Google drive here-
My_Ref Fremen Edition GB (14th GB)
Best parts on Dario's Google drive here-
My_Ref Fremen Edition GB (14th GB)
I am finally looking forward to building one of these! Does anyone know of a monoblock chassis that only has one heatsink, similar to the ACA original chassis? Seems silly to be paying for an unused heatsink ��. If not does one of the Dissapante 2U (300mm) work well for a stereo build?
Yes but please refer to the Google Docs one, the Mouser BOM is still valid but some parts have to be deleted (R3, R3 Heatsink)
If you're looking at the DIYAUdio Store you can use this one (steel covers) or this (Aluminum covers and 10mm aluminum front panel), choose 230x280mm, the side panel heatsink is enough for the My_Ref, with the same chassis I've built a very compact STEREO set, still in use by my brother.
Two of such monoblocks, side by side, are about 19".
If you can also order them directly from the HiFi 2000 store:
Silver or Black.
But I think that for US buyers it's cheaper from DIYA Store.
In a previous 'standard' Gainclone build I did a few years ago I included Zobel & Thiele networks on the output to minimise any potential issues due to inductive or capacitive loads respectively, just to make sure!
That said, my cable runs to speakers are only around 3 metres or so max ... 8 Ohm speakers, HiVi Research (i.e., Swans) full range + Fountek tweeter.
So, my question is would there be any benefit to include these with my proposed My_Ref Fremen build as well, or not really necessary do you think?
That said, my cable runs to speakers are only around 3 metres or so max ... 8 Ohm speakers, HiVi Research (i.e., Swans) full range + Fountek tweeter.
So, my question is would there be any benefit to include these with my proposed My_Ref Fremen build as well, or not really necessary do you think?
Build as shown
The feedback loops (or nets) are optimized for load tolerance and more importantly, fast clipping recovery. Some have posted they drive very low sensitivity speakers loud and never heard the amplifier clip. It is most likely clipping a lot.
The Evo build, which all14th Group Buy are is less sensitive to speaker reactance. I have driven many different speakers with no issues as designed.
The feedback loops (or nets) are optimized for load tolerance and more importantly, fast clipping recovery. Some have posted they drive very low sensitivity speakers loud and never heard the amplifier clip. It is most likely clipping a lot.