Hi Jac, the seller still has some packs of 8 RJH left, i'll let you know when they turn up. It could still be a while before I get all the components together for my second build at this rate.
I still haven't decided what to use for R10
It absolutely make some difference, at least in my experience.
Same thing for wire gauge, one note though... did you pay attention to orientation? OCC wire is directional and some of the differences you heard may be due to it.
In my experience it does but everyone is free to do as they like
They should be genuine, one of the batches of RJHs of the GB was buyed from that seller.
Can't wait to read your impressions about it...
Thanks Dario, my industrial BOM FE's are so good that I've been in no hurry to complete my second set. I'm getting curious now though about the improvement I can get from premium components.
Did you settle on a resistor type for R10? I seem to remember reading somewhere that you preferred the KOA carbon film in the industrial BOM. That would be good price wise but if a reasonable improvement can be got by fitting something more expensive I might go for it. As long as it doesn't make the amps sound too bright.
Did you settle on a resistor type for R10? I seem to remember reading somewhere that you preferred the KOA carbon film in the industrial BOM. That would be good price wise but if a reasonable improvement can be got by fitting something more expensive I might go for it. As long as it doesn't make the amps sound too bright.
Reading up on naked foil resistors I found these and thought they might be of interest to some -
TX2575 (the Z-Foil upgrade to the TX2352)
I might try some, they even accept paypal, handy!
TX2575 (the Z-Foil upgrade to the TX2352)
I might try some, they even accept paypal, handy!
That is the "naked Vishay Z-foil" we've been discussing several times over the past few months. It is the best resistor I have heard at R10, including cheap metal film, Vishay/Dale metal film, PRP metal film, Shinkoh tantalum, Riken carbon film, and Caddock MK-132. Worth every penny. It does not produce any brightness or seem to make much sound of its own, but it is very transparent. If you have source problems, it will pass them along without masking. If you have musical sources, it will pass music without coloration.
Peace,
Tom E
Peace,
Tom E
So, if I understand this correctly, Tom likes the naked Z at R10 and Dario suggests the surface mount version at R12 (see Group Buy BOM, comments on the right side). Has anyone tried both R10 and R12? Or is that too much naked Z? Expensive too.
Any comments on the choice between R10 and R12?
Jac
Musings on Component Sensitivity
I have been playing around on the Pass Labs side of things. I haven't finished my Pass Amp, too easily distracted I guess. But the guys over there don't seem to believe in component choices affecting sound quality very much, especially in the passive components.
My experience with the My_Ref FE is that passive components make a big difference in tonal quality, detail, and stage presentation. I was curious if this was due to the My_Ref design or common in other amps, just not in line with the philosophy of the group.
I decided to try a completely different type of amp and see if it responded the same way as the My_Ref to components, in this case, the input capacitor. I have an old CMoy headphone amplifier hanging around and I decided to modify it so that I could easily swap input capacitors, including some large caps from FE experimentation. In addition to my own ears, I included a couple of guys at work, ones that haven't played with components and don't have any preconceived ideas about these things.
It turns out that all evaluators could hear a difference between a small polyester box cap (Vishay BC) and a Mundorf Supreme. The guys at work all thought that the Mundorf was cleaner and better sounding with more damping on the bass. In addition, I tried several more caps of different materials and design. My conclusion is that some differences were there between caps, but the differences were smaller than I experienced in the My_Ref FE. More than that, they were primarily tonal differences, with maybe a little clarity in the most extreme examples. None of the sound stage differences were noticeable, although I admit that headphones are the best for sound stage.
Thinking about why different amp designs are sensitive to components while others are less so, I come to the following. Most amp designs try to isolate the output from the input and feedback. They try to drive the speaker as a purely voltage device. The My_Ref is a current output amplifier and because the speaker is a voltage sensitive device, the impedance curve of the speaker is involved with and affected by the output of the amplifier. This was laid out more clearly than I can by Mauro in his explanation of the My_Ref.
What makes the My_Ref different is that the impedance of the speaker and of passive components in the feedback or even input chain all affect the way that the system sounds. So a resistor in the feedback loop, a capacitor between that feedback loop and ground, and an input capacitor all have unique impedance behavior and all result in a different sound quality. In other words, the design of the My_Ref amp is inherently sensitive to components and that is a good thing because it opens up sound stage and clarity with better components. The same is likely less true of other amp designs. At least that is how I understand the situation.
Now I don't claim to know this as fact, just my current understanding. Please feel free to correct and inform me further if I am understanding this incorrectly. Any thoughts?
Jac
I have been playing around on the Pass Labs side of things. I haven't finished my Pass Amp, too easily distracted I guess. But the guys over there don't seem to believe in component choices affecting sound quality very much, especially in the passive components.
My experience with the My_Ref FE is that passive components make a big difference in tonal quality, detail, and stage presentation. I was curious if this was due to the My_Ref design or common in other amps, just not in line with the philosophy of the group.
I decided to try a completely different type of amp and see if it responded the same way as the My_Ref to components, in this case, the input capacitor. I have an old CMoy headphone amplifier hanging around and I decided to modify it so that I could easily swap input capacitors, including some large caps from FE experimentation. In addition to my own ears, I included a couple of guys at work, ones that haven't played with components and don't have any preconceived ideas about these things.
It turns out that all evaluators could hear a difference between a small polyester box cap (Vishay BC) and a Mundorf Supreme. The guys at work all thought that the Mundorf was cleaner and better sounding with more damping on the bass. In addition, I tried several more caps of different materials and design. My conclusion is that some differences were there between caps, but the differences were smaller than I experienced in the My_Ref FE. More than that, they were primarily tonal differences, with maybe a little clarity in the most extreme examples. None of the sound stage differences were noticeable, although I admit that headphones are the best for sound stage.
Thinking about why different amp designs are sensitive to components while others are less so, I come to the following. Most amp designs try to isolate the output from the input and feedback. They try to drive the speaker as a purely voltage device. The My_Ref is a current output amplifier and because the speaker is a voltage sensitive device, the impedance curve of the speaker is involved with and affected by the output of the amplifier. This was laid out more clearly than I can by Mauro in his explanation of the My_Ref.
What makes the My_Ref different is that the impedance of the speaker and of passive components in the feedback or even input chain all affect the way that the system sounds. So a resistor in the feedback loop, a capacitor between that feedback loop and ground, and an input capacitor all have unique impedance behavior and all result in a different sound quality. In other words, the design of the My_Ref amp is inherently sensitive to components and that is a good thing because it opens up sound stage and clarity with better components. The same is likely less true of other amp designs. At least that is how I understand the situation.
Now I don't claim to know this as fact, just my current understanding. Please feel free to correct and inform me further if I am understanding this incorrectly. Any thoughts?
Jac
I think (no way of measuring) that all these "good" attributes come from the low tempco combined with the low temperature rise giving rise to an ultra low resistance change.
Goodness = constant resistance.
Badness = varying resistance.
whether that is due to age, humidity, soldering, power dissipation, tempco, etc.
Yes.
The MyRef is like all other Voltage output amplifiers.
It just happens to use a Howland "inside" to define the operating voltages and currents.
If cable composition can affect sound quality then components will do likewise. I can hear clear differences between a decent carbon pot and a stepped attenuator with metal film resistors. This amounts to a change of component directly in the signal path affecting sound quality. The next component in the chain is the amplifiers DC blocking cap, I'm not surprised that people report changes when trying better quality components in certain key areas like this one.
Hi Mark, Andrew, Davy,
Thank you for your replies. I managed to dig up Mauro Penasa's paper, "The Project My Reference". I was attempting to extend his comments to why the Mr_Ref might be more sensitive to components than other amps. It essentially agrees with Andrew's statement above, but seem to put more importance on the way that the Howland interacts with the load.
"Probably the most important feature, from an “audio” point of view, is that:
As a whole, the complete circuit works like if it were a common, normal Voltage Opamp,
because the high open loop output impedance becomes compensated by the applied negative
feedback, according to the following:
Rout=Rint / (1+Aol*beta) where beta= R/ (R+Rf) (beta=feedback factor)
But, looking closer at the above equations and the circuit, we can observe that the Load,
because of the unique functionality of G1, becomes an integral part of the transfer function,
because the signal that feeds the NFB network is not simply Vout(G1), but Iout(G1) Zload!
All the nonlinearities of the Zload become highly apparent at the input terminals of the
differential pair, which now can proceed to compensate for them. [by driving the output current
of G1 accordingly.] In a conventional setup, the open loop output impedance is generally much
lower with respect to the load, and so the NFB network works by sampling the amps output
voltage. (Vout=Av*Vin) In this way the circuit, though it will be highly immune to the load
variations, it will become too much self-referent and as such will not be able to compensate for
the dynamic interfacing problems between the loudspeaker and amplifier."
If I did this correctly, I attached the paper to this post.
Since Mauro is saying that the voltage output of current pump is a function of the load and that it's impedance refers back to the input, does that make it different from other types, especially in regard to the impedance of the load and other components in the feedback loop? I'm far from an expert here and just trying to understand.
Thanks again for your feedback.
If you connect a speaker with a 8 ohm tweeter and a 4 ohm woofer, the voltage gain of the LM3886 for the higher frequencies will be higher than for the lower frequencies, this is what you are explaining and it is correct but it is not the whole story. The LM318 compares the voltage feedback from the output with the input signal and compensates/corrects the global voltage gain. This completely removes the current pump function of the amp.
Update, in the end I ordered charcroft Z foils for R10, Amtrans AMCH for C12, 30 & 32 oh and Mundorf Supreme for C13. All for £68 inc delivery from hifi collective.
I have more BG FK's (4v) on their way from parts connexion for C9 and the 8 x Elna RJH for C1 & 2 I ordered from the Polish ebay seller turned up yesterday.
The only thing I've left out from the premium BOM is the Mundorf M-lythic AG caps for the power supply. I might just keep the Panasonic ones, not fully decided on that one yet.
I have more BG FK's (4v) on their way from parts connexion for C9 and the 8 x Elna RJH for C1 & 2 I ordered from the Polish ebay seller turned up yesterday.
The only thing I've left out from the premium BOM is the Mundorf M-lythic AG caps for the power supply. I might just keep the Panasonic ones, not fully decided on that one yet.
Experiments in C9 and C13 Combinations
Subjective evaluations only. The usual disclaimers. Works for my system, my ears, etc. Your results may vary.
I was interested in Siva's proposal for C9 of the Nichicon UD, but this evaluation is catching up on some capacitors that I got a while ago, so trying a UD will have to wait.
For C9,
my baseline was the Blackgate PK 220 uF, 4 V
Candidate caps that were new to me were:
Jensen 220 UF, 63 V axial (marked DK-025790-1 and sold by PCX about $15)
Mundorf E-Cap 220 uF, 63 V axial RAW (sold by PCX about $3.50)
Blackgate NX 220 uF, 6.3 V radial NOS (about $15 on ebay)
At C13, 4 of my favorites, each with their own character.
Mundorf Supreme 1 uF, 600 V (Dario's recommend cap, about $19)
Mundorf Silver Oil 1 uF, 1000 VDC (about $62, ouch)
Rike S-Cap, 1 uF, 600VDC (about $49)
K75-10 1 uF, 250 V + Amtrans AMCH 1 nF, 100 V (about $7 combined price)
Those prices are all PCX current prices. I admit, I got them some time ago and for a fair bit cheaper. By the way, you can save a few dollars on the Mundorf film caps at Madisound. The Jensen's were an experiment by Tom E that he never got around to. He offered them to me and I'm very glad. Thank you Tom.
I spent time over a few months listening to each cap and most combinations before sitting down and making more direct comparisons. What came out of this were several combinations that worked together well and others where certain strengths combined in less than ideal ways. For example, the Mundorf Supreme is a very neutral, slightly laid back cap. In contrast, the Mundorf Silver Oil has more detail and dynamics with more energy in the top octaves. The Blackgate NX is an excellent C9 that also has more detail and high end energy. If you combine the NX with the Supreme, you get a nice open sound with added detail. However, when I combined the NX with the Silver Oil, the result felt strained, even slightly harsh, at the top end. Even female voices singing upper harmony seemed strained, even etched a little. I guess that just proves that you can have too much of a good thing.
Looking at the other C13 caps with the NX, I liked the Rike S-Cap just slightly better than the Supreme when paired with the NX. The S-Cap as a slightly more open sound and clearly has better dynamics, and darker background. Overall, both are very good when combined with the NX. The K75/Amtrans combo also sound full and fluid with good detail, just not quite as much as with the other caps. Since the NX improves detail from C9, the NX is probably the best choice for the K75/Amtrans combo.
Looking back at the Blackgate PK baseline, it remains a very nice cap. Compared to the NX, the NX as more detail on offer, but the PK is slightly more laid back. Very nice and I don't worry at all about building with the PK. Obviously, the PK takes advantage of a C13 that offers more detail, like the Silver Oil. That combination approaches, perhaps equals, the NX with the Supreme.
The Mundorf E-Cap at C9 is an OK cap with a reasonable price, but frankly speaking, it is just too big to fit. That, plus it doesn't offer any improvement over the PK so I don't see the point of pursuing the E-Cap.
That leaves us with the Jensen C9. As an axial, it is definitely a challenge to fit properly. Tom E thought you could lay it down by using a different ground point, but I will probably try mounting it soldier style.
Combine the Jensen with the Supreme or the K75/Amtrans and you have a very nice sound with good detail, but perhaps missing a little sparkle on top. Combined with the S-Cap and it's a bit better with darker background and excellent dynamics. But the prize combination is the Silver Oil with the Jensen. At least in my system, those caps are made for each other. Excellent detail, black background, full rich bass and mids, dynamic, and clean. Definitely my new favorite. Those caps will be staying in my main system for a very long time.
So take this all with a grain of salt. It might not work the same in your system. And remember that these two caps in particular interact to affect the sound of your FE.
Jac
Subjective evaluations only. The usual disclaimers. Works for my system, my ears, etc. Your results may vary.
I was interested in Siva's proposal for C9 of the Nichicon UD, but this evaluation is catching up on some capacitors that I got a while ago, so trying a UD will have to wait.
For C9,
my baseline was the Blackgate PK 220 uF, 4 V
Candidate caps that were new to me were:
Jensen 220 UF, 63 V axial (marked DK-025790-1 and sold by PCX about $15)
Mundorf E-Cap 220 uF, 63 V axial RAW (sold by PCX about $3.50)
Blackgate NX 220 uF, 6.3 V radial NOS (about $15 on ebay)
At C13, 4 of my favorites, each with their own character.
Mundorf Supreme 1 uF, 600 V (Dario's recommend cap, about $19)
Mundorf Silver Oil 1 uF, 1000 VDC (about $62, ouch)
Rike S-Cap, 1 uF, 600VDC (about $49)
K75-10 1 uF, 250 V + Amtrans AMCH 1 nF, 100 V (about $7 combined price)
Those prices are all PCX current prices. I admit, I got them some time ago and for a fair bit cheaper. By the way, you can save a few dollars on the Mundorf film caps at Madisound. The Jensen's were an experiment by Tom E that he never got around to. He offered them to me and I'm very glad. Thank you Tom.
I spent time over a few months listening to each cap and most combinations before sitting down and making more direct comparisons. What came out of this were several combinations that worked together well and others where certain strengths combined in less than ideal ways. For example, the Mundorf Supreme is a very neutral, slightly laid back cap. In contrast, the Mundorf Silver Oil has more detail and dynamics with more energy in the top octaves. The Blackgate NX is an excellent C9 that also has more detail and high end energy. If you combine the NX with the Supreme, you get a nice open sound with added detail. However, when I combined the NX with the Silver Oil, the result felt strained, even slightly harsh, at the top end. Even female voices singing upper harmony seemed strained, even etched a little. I guess that just proves that you can have too much of a good thing.
Looking at the other C13 caps with the NX, I liked the Rike S-Cap just slightly better than the Supreme when paired with the NX. The S-Cap as a slightly more open sound and clearly has better dynamics, and darker background. Overall, both are very good when combined with the NX. The K75/Amtrans combo also sound full and fluid with good detail, just not quite as much as with the other caps. Since the NX improves detail from C9, the NX is probably the best choice for the K75/Amtrans combo.
Looking back at the Blackgate PK baseline, it remains a very nice cap. Compared to the NX, the NX as more detail on offer, but the PK is slightly more laid back. Very nice and I don't worry at all about building with the PK. Obviously, the PK takes advantage of a C13 that offers more detail, like the Silver Oil. That combination approaches, perhaps equals, the NX with the Supreme.
The Mundorf E-Cap at C9 is an OK cap with a reasonable price, but frankly speaking, it is just too big to fit. That, plus it doesn't offer any improvement over the PK so I don't see the point of pursuing the E-Cap.
That leaves us with the Jensen C9. As an axial, it is definitely a challenge to fit properly. Tom E thought you could lay it down by using a different ground point, but I will probably try mounting it soldier style.
Combine the Jensen with the Supreme or the K75/Amtrans and you have a very nice sound with good detail, but perhaps missing a little sparkle on top. Combined with the S-Cap and it's a bit better with darker background and excellent dynamics. But the prize combination is the Silver Oil with the Jensen. At least in my system, those caps are made for each other. Excellent detail, black background, full rich bass and mids, dynamic, and clean. Definitely my new favorite. Those caps will be staying in my main system for a very long time.
So take this all with a grain of salt. It might not work the same in your system. And remember that these two caps in particular interact to affect the sound of your FE.
Jac