Inside
No heatsinks. Used chassis and then needed plate and CPU cooler. First transformers gave 37 volt rails and it ran hot. Changed out before the LM3886 gave up.
Using line input transformers instead of an input coupling cap to block DC. Have two installed, a Jensen and a Cinemag 4:1 stepdowns. Just resoldet the leads to swap for comparison.
DAC used is balanced only, prefer line transformer to cap and leads to convert balanced to SE.
No heatsinks. Used chassis and then needed plate and CPU cooler. First transformers gave 37 volt rails and it ran hot. Changed out before the LM3886 gave up.
Using line input transformers instead of an input coupling cap to block DC. Have two installed, a Jensen and a Cinemag 4:1 stepdowns. Just resoldet the leads to swap for comparison.
DAC used is balanced only, prefer line transformer to cap and leads to convert balanced to SE.
Attachments
Boardwork
I always install a snubber across the 10,000 ufd reservoir caps and 22 ufd caps directly to the legs of the LM3886. This gives a 20 to one drop in capacitance for decoupling, 10K, 470, and 22 ufd.
The snubber is 0.1 ohm Dale and 47 nfd Siemens stacked film because this is what I have.
The total lead length for the two Panasonic 22ufd 50v FM caps is under 1 cm. Should be low inductance.
The picture is from another amp, but all my My_Ref, Evo, and FE are the same.
I always install a snubber across the 10,000 ufd reservoir caps and 22 ufd caps directly to the legs of the LM3886. This gives a 20 to one drop in capacitance for decoupling, 10K, 470, and 22 ufd.
The snubber is 0.1 ohm Dale and 47 nfd Siemens stacked film because this is what I have.
The total lead length for the two Panasonic 22ufd 50v FM caps is under 1 cm. Should be low inductance.
The picture is from another amp, but all my My_Ref, Evo, and FE are the same.
Attachments
Took photos of my resting MyRef. Will need to clean it, upgrade components, order (finally) front panels from somewhere so it looks better and to connect to other parts of the chain.
My wife is leaving for a few weeks so I will be alone at home- perfect time to complete everything.
My wife is leaving for a few weeks so I will be alone at home- perfect time to complete everything.
Attachments
Sorry, I didn't see this.
I'm using a DIY Relaixed2 pre. It has 6 dB gain on SE and 9 dB on balanced.
I'm using a DIY Relaixed2 pre. It has 6 dB gain on SE and 9 dB on balanced.
I am using the Canare 4S11 right now and it sounds pretty good, inexpensive as well. I would recommend you to try this.
One word of caution, there are many counterfeit of Canare cables. Cheers.
Phono preamp specs ?
So ... I'm excited to build the FE My_Ref ! Following on Vox's question ....
I *might* want to build a phono preamp (MM/MC) once this project is complete and running. Anything I should know about component matching? (Newbie here). I don't want to assume that the FE works with any preamp I might buy or build, only to find that it doesn't, or worse -- gets damaged by a bad choice ! (I'm currently running 1990's era Linn audio preamp + amps, PSB speakers).
- Paul
So ... I'm excited to build the FE My_Ref ! Following on Vox's question ....
I *might* want to build a phono preamp (MM/MC) once this project is complete and running. Anything I should know about component matching? (Newbie here). I don't want to assume that the FE works with any preamp I might buy or build, only to find that it doesn't, or worse -- gets damaged by a bad choice ! (I'm currently running 1990's era Linn audio preamp + amps, PSB speakers).
- Paul
Paul,
The FE plays well with most preamps. Your Linn should be fine. Many have tried using a good quality stereo potentiometer to control volume with nothing else needed. That works fine.
Others have used transformer volume control, light sensitive resistor volume control (like Uriah's Clone Note - Clone Note aka Lighter Note rev 4), and step attenuators (like mine). You can have some gain (mine is 9 dB gain in the pre) or no gain like a potentiometer. It's nice to have a relatively low output impedance from the pre, but that's not critical since the FE has a 100k input impedance. I can't recall a specific case of a tube based pre being used with FE, but I'm sure that would good too.
If you use a transformer based pre, you get DC isolation from the transformer, so C13 isn't needed and can be replaced with a jumper. In sum, you should be fine with most preamps that spark your interest. I hope that helps.
Jac
The FE plays well with most preamps. Your Linn should be fine. Many have tried using a good quality stereo potentiometer to control volume with nothing else needed. That works fine.
Others have used transformer volume control, light sensitive resistor volume control (like Uriah's Clone Note - Clone Note aka Lighter Note rev 4), and step attenuators (like mine). You can have some gain (mine is 9 dB gain in the pre) or no gain like a potentiometer. It's nice to have a relatively low output impedance from the pre, but that's not critical since the FE has a 100k input impedance. I can't recall a specific case of a tube based pre being used with FE, but I'm sure that would good too.
If you use a transformer based pre, you get DC isolation from the transformer, so C13 isn't needed and can be replaced with a jumper. In sum, you should be fine with most preamps that spark your interest. I hope that helps.
Jac
Jac, thanks for your response ! Good to know a bit more of the options available. I spent a delightful evening reading about the Clone Note preamp, and reading about LDR designs. I'm starting to get familiar with some of the preamp projects that have developed a following on these pages. It's a lot to take in, but I'm enjoying the journey.
I've got all the parts for an Aikido and a Hagerman Clarinet build. Hoping to pair one of them with some boards from the 14th GB.
I have used a tube preamplifier with Rev C, not an Evo. Believe it or not, the coupling cap size on the preamp had to be increased. Assume the feedback loop of the Rev C effected the bandwidth.
No longer use a real preamp. Use the monitor outputs from recording interfaces. These are designed to drive 600 ohm loads. I think that is critical. Low output impedance and good voltage swing.
I tried a home Brew tube preamp with 6080 tubes. Could dump an amp. Not some weenie opamp with 50 mA. It needed a 8 ufd coupling cap. Then the My-Ref sang with full voice. First tried a 1 ufd coupling cap and it sounded like a high pass filter.
No longer use a real preamp. Use the monitor outputs from recording interfaces. These are designed to drive 600 ohm loads. I think that is critical. Low output impedance and good voltage swing.
I tried a home Brew tube preamp with 6080 tubes. Could dump an amp. Not some weenie opamp with 50 mA. It needed a 8 ufd coupling cap. Then the My-Ref sang with full voice. First tried a 1 ufd coupling cap and it sounded like a high pass filter.
My_Ref FE and Evo A mod
After reading about the FE compensation and the Evo A compensation, in particular the build thread and Dario's excellent tutorial, I must say I'm still confused. I don't have the technical training or experience with other projects to know what the choices mean. I read that the EVO Rev A Mod gives the amp more stability, which sounds good to me, but maybe I'm not seeing the big picture. Since this is the time to decide which variation to build, I'd like to hear from folks -- which variation is more common? In layman's terms, what are the trade-off's of one vs the other?
After reading about the FE compensation and the Evo A compensation, in particular the build thread and Dario's excellent tutorial, I must say I'm still confused. I don't have the technical training or experience with other projects to know what the choices mean. I read that the EVO Rev A Mod gives the amp more stability, which sounds good to me, but maybe I'm not seeing the big picture. Since this is the time to decide which variation to build, I'd like to hear from folks -- which variation is more common? In layman's terms, what are the trade-off's of one vs the other?
Hi truepaul,
I recommend that you build the Evo Rev. A version. Most folks are building that these days as it is a bit more stable and sounds as good or better than the original. That is the simplest and most reliable way have success and to get support if you should have a problem.
I would also recommend that you stay with the LM318 op amp for your first experience. As you read the forums, you may see crazy people like George (not really crazy, actually really smart) and me playing around with alternate op amps. They are an interesting alternative but add stability risk and the LM318 amplifier sounds just great.
Probably the best bet for your first build is to choose either the Mouser BOM or the "Suggested Best Part" so you can hear how it is supposed to sound. If you do get the urge to swap a few components after building the BOM, C9 and C13 seem to make the biggest difference in sound character of the amp.
Jac
BTW No problem posting here, but you would probably get more response on the Build Thread and Tutorial, even if it is an insanely long thread.
My_Ref Fremen Edition - Build thread and tutorial
I recommend that you build the Evo Rev. A version. Most folks are building that these days as it is a bit more stable and sounds as good or better than the original. That is the simplest and most reliable way have success and to get support if you should have a problem.
I would also recommend that you stay with the LM318 op amp for your first experience. As you read the forums, you may see crazy people like George (not really crazy, actually really smart) and me playing around with alternate op amps. They are an interesting alternative but add stability risk and the LM318 amplifier sounds just great.
Probably the best bet for your first build is to choose either the Mouser BOM or the "Suggested Best Part" so you can hear how it is supposed to sound. If you do get the urge to swap a few components after building the BOM, C9 and C13 seem to make the biggest difference in sound character of the amp.
Jac
BTW No problem posting here, but you would probably get more response on the Build Thread and Tutorial, even if it is an insanely long thread.
My_Ref Fremen Edition - Build thread and tutorial
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Jac is a smart dude too. His are excellent suggestions.
.. and the build guide is insanely big ;>)
Cheers, Pete
Last revision boards do not have a choice, only the Evo A compensation is supported, the pads for FE one are gone...
Thanks to everyone for the quick response !
The choice of the Evo A is already made, and I am happy to proceed, without worry of making the "wrong" choice! Excellent ! I'm looking forward to this project !
The choice of the Evo A is already made, and I am happy to proceed, without worry of making the "wrong" choice! Excellent ! I'm looking forward to this project !
George: I took the plunge and switched my opamp from the LM318 to your suggested OPA828 in my first build. I've been liking my ADA4627 build version EVO A better than the LM318 version (with all respect and reverence to Dario's hard work with component matching; both using Ver 1.72 boards). I think my old ears just found the LM318 opamps + cerefines just too "contained" even though the balanced and airy sound of the Evo A builds still brings one to the point of tears. I used a silver mica 68pF at C32 but I remember reading Jac preferred a polystyrene at that position. 5pF across pins 2&6.
I'm still deciding how to build the newest Ver 1.8 boards up.
Cheers, Pete
