My summer experiences with the Jfet discrete (Pass) amps is at the core of this experiment. They produce excellent sound and are the preference for thousands of amp builders. It's my contention that the FEs create a more dynamic and colorful sound with equal clarity, a deeper stage and a generally more "Live" presentation. The first stop will be with a major discrete amp guru/expert for that comparison . There are a couple other heavy-hitter DIYer including Uriah, who will give the amp a listen.
As reported on another thread. I have the resources to get direct comparisons to high-end tube and solid state amps right here in my community. Those will happen after I complete my "final version" build. These are RCs, but they are fully capable of demonstration the sound quality of Dario's design.
But since you mentioned it - I might try to hook up with some additional audio shops while these are in circulation.
As reported on another thread. I have the resources to get direct comparisons to high-end tube and solid state amps right here in my community. Those will happen after I complete my "final version" build. These are RCs, but they are fully capable of demonstration the sound quality of Dario's design.
But since you mentioned it - I might try to hook up with some additional audio shops while these are in circulation.
It's my understanding that the strongest field comes perpendicular from the "Doughnut Hole" at the core of a toroid transformer. I tried to locate that over the PS section of the FE boards. It's still extremely close to the signal elements - but there doesn't appear to be a problem.
If your monoblocks have the transformer mounted to the bottom plate of your chassis, that can only aid in defeating any interference.
Cheers Bob, I had planned to mount the transformer on the bottom plate. I was going to order two new ones but I have decided to re-use the enclosure and 22v 300Va transformer I already have. I have ordered another identical enclosure for the other monoblock along with an extra back panel for the original enclosure. This means I now only need to buy a second transformer and that's everything taken care of.
I might even get everything in time for Christmas
I might even get everything in time for Christmas
But since you mentioned it - I might try to hook up with some additional audio shops while these are in circulation.
Now Bob,
Be careful how you state things. We wouldn't want to think of you as an audio slut.
I'm very interested in the opinion of your tube and Pass experts. Please keep us informed.
Jac
Bob, that's an interesting minimalistic placement of boards, connectors, trafos, etc. - the bulk of the weight is contributed by the trafos, I expect.
Regarding the hum, it depends on how the earth wire to the shield is connected - in some cases, it creates a half-turn winding on the trafo that can contribute a significant hum (probably of the order of 100s of mV).
In this respect, the waist-belt copper-foil shield on EI trafos is better - almost any Earth connection to the band doesn't create an additional parasitic winding on the core.
I used four 160va ApexJr toroids and even with 105 db/w compression drivers I can happily say that I cannot hear them.
It's very amusing to here the mic gain hiss in some recordings and know that its not coming for your components.
Has anyone tried soldering the low level input directly to the board?
The pins are convenient but could compromise the signal.
It's very amusing to here the mic gain hiss in some recordings and know that its not coming for your components.
Has anyone tried soldering the low level input directly to the board?
The pins are convenient but could compromise the signal.
Attachments
Thanks Siva. It will be fun to translate the compact size into all metal. I'll post when it's done.
The extra shield produced a hum so strong that it could possibly cause speaker damage. I'll investigate further when the amp gets back.
damuffin - I did solder the input wires a week or so ago when I was hunting down a problem while connecting the Lighter Note. It turned out to be lost contact on the pin of a Neutrik RCA socket, but that was only discovered after I had soldered the inputs. I had those little green terminal blocks on at the time, thinking they offered better contact than the pins. Still might try to find some high quality pieces like that just for convenience.
It was only about an hour but I didn't notice any significant improvement with the soldered wires. I did put the pins back in for this latest configuration, but I've always thought I would solder everything signal related once I complete the final version boards. Dario included TH pads for use even on the outputs if a builder wishes to use them.
Haven't investigated, but maybe rear mounted RCAs and posts might be a solution to the removal problem with solid connections.
The extra shield produced a hum so strong that it could possibly cause speaker damage. I'll investigate further when the amp gets back.
damuffin - I did solder the input wires a week or so ago when I was hunting down a problem while connecting the Lighter Note. It turned out to be lost contact on the pin of a Neutrik RCA socket, but that was only discovered after I had soldered the inputs. I had those little green terminal blocks on at the time, thinking they offered better contact than the pins. Still might try to find some high quality pieces like that just for convenience.
It was only about an hour but I didn't notice any significant improvement with the soldered wires. I did put the pins back in for this latest configuration, but I've always thought I would solder everything signal related once I complete the final version boards. Dario included TH pads for use even on the outputs if a builder wishes to use them.
Haven't investigated, but maybe rear mounted RCAs and posts might be a solution to the removal problem with solid connections.
A DCB1 buffer board and 4 matched transistors arrived today, Shaun (shoom) sent them to me, I offered but he did not want payment for them. The world needs more shoom's in my opinion, a scholar and a gentleman!
A nice buffer project to compliment the FE amps which I hope to get finished in time for Christmas.
This hobby is addictive
A nice buffer project to compliment the FE amps which I hope to get finished in time for Christmas.
This hobby is addictive
As long as you can still call it a hobby, you're in good shape. When it turns into a core lifestyle - we need an intervention.
lol, fortunately I have a missis who will intervene if it gets out of hand.
The FE and DCB1 will need to be the limit for the electronics side of things for quite some time.
A diy speaker build comes next
I used four 160va ApexJr toroids and even with 105 db/w compression drivers I can happily say that I cannot hear them.
It's very amusing to here the mic gain hiss in some recordings and know that its not coming for your components.
Has anyone tried soldering the low level input directly to the board?
The pins are convenient but could compromise the signal.
That's how I hope my final build will be like.
Are you using passive bi-amplification?
Rike Audio S-Cap for C13
I've been letting the Rike S-Caps settle and there might be a bit more settling with more time, but I'm pretty confident that I have a good evaluation.
Right out of the box, they have some emphasis on the treble range which makes the bass and mid-range seem a bit recessed. Given some playing time and that evens out to a very balanced and clear sound.
I used the K71-4 caps from the budget BOM as a baseline for comparison. I've always found these caps to be very clear and balanced, just lacking a bit of warmth and harmonic tone in the mid-range. I have never thought of the K71-4 as having a veiled sound at all. I've played the K71-4 enough now that they feel very comfortable and natural.
The Rike S-Caps are in a similar overall character but a clear step above for sound quality. They have a clarity and separation between instruments that makes the K71-4 seem a bit veiled.
The soundstage of the S-Cap is similar in size but each instrument is more clearly located and defined than the K71. There is also a noticeable improvement in dynamics; quiet spaces in the music are more silent, quiet instruments are quieter, and louder notes are louder and more forward. I have no idea how this kind of difference can be coming from a cap, but I'm not the only one who noticed it. Tony Gee also commented favorably on the dynamic range of this cap. Another difference is instrument harmonics. There is more sense of the recording room with this cap than the K71-4.
Overall, there is a lot to like in this cap. It is probably the most neutral cap I have auditioned with this amp. I mentioned that it has a similar character to the K71-4 and that may be the reason that preference for this cap will depend on the listener preference and system characteristics. I found this cap to be very clear and accurate but lacking a bit of warmth. It is kind of surprising to find a paper-in-oil cap that sounds cool, but that just shows that cap design is much more than capacitance value and voltage rating. If your preference is for clarity, precision, and neutrality or your system is naturally warm and can stand a cooler cap in the mix, this cap may be worth listening to.
Given my earlier taste in caps, you might be wondering how the S-Cap rates with my favorite K75-10 plus bypass. I would say that they are equally good, just a different choice. As my system currently stands, I enjoy the warmth of the K75s, so I just put them back in the amps and will leave them there. But the S-Cap is the best cap without a bypass I have tried in the FE I can easily imagine putting them back into the system on a different day.
I hope others give the S-Cap a try and report. They do seem like an interesting alternative to the True Copper, depending on what your system needs. I look forward to your comments.
Jac
I've been letting the Rike S-Caps settle and there might be a bit more settling with more time, but I'm pretty confident that I have a good evaluation.
Right out of the box, they have some emphasis on the treble range which makes the bass and mid-range seem a bit recessed. Given some playing time and that evens out to a very balanced and clear sound.
I used the K71-4 caps from the budget BOM as a baseline for comparison. I've always found these caps to be very clear and balanced, just lacking a bit of warmth and harmonic tone in the mid-range. I have never thought of the K71-4 as having a veiled sound at all. I've played the K71-4 enough now that they feel very comfortable and natural.
The Rike S-Caps are in a similar overall character but a clear step above for sound quality. They have a clarity and separation between instruments that makes the K71-4 seem a bit veiled.
The soundstage of the S-Cap is similar in size but each instrument is more clearly located and defined than the K71. There is also a noticeable improvement in dynamics; quiet spaces in the music are more silent, quiet instruments are quieter, and louder notes are louder and more forward. I have no idea how this kind of difference can be coming from a cap, but I'm not the only one who noticed it. Tony Gee also commented favorably on the dynamic range of this cap. Another difference is instrument harmonics. There is more sense of the recording room with this cap than the K71-4.
Overall, there is a lot to like in this cap. It is probably the most neutral cap I have auditioned with this amp. I mentioned that it has a similar character to the K71-4 and that may be the reason that preference for this cap will depend on the listener preference and system characteristics. I found this cap to be very clear and accurate but lacking a bit of warmth. It is kind of surprising to find a paper-in-oil cap that sounds cool, but that just shows that cap design is much more than capacitance value and voltage rating. If your preference is for clarity, precision, and neutrality or your system is naturally warm and can stand a cooler cap in the mix, this cap may be worth listening to.
Given my earlier taste in caps, you might be wondering how the S-Cap rates with my favorite K75-10 plus bypass. I would say that they are equally good, just a different choice. As my system currently stands, I enjoy the warmth of the K75s, so I just put them back in the amps and will leave them there. But the S-Cap is the best cap without a bypass I have tried in the FE I can easily imagine putting them back into the system on a different day.
I hope others give the S-Cap a try and report. They do seem like an interesting alternative to the True Copper, depending on what your system needs. I look forward to your comments.
Jac
Last edited:
Hello Jac,
thank for your review, where did you buy K75 ? I have red some reviews and I would like to try them, they are not expensive too. I have found them only on ebay, there is some shops in Romania that sell them (can I link the shop ??). In the same shop I have found four K75 for 10$ and Teflon K72P-6 for possibly bypass. Witch is the right value for bypass capacitor? ... 0,039uf is it right ?
Hello Marco,
I purchased my K71-4 and my K75-10 on ebay from valtek_2005. He is in Romania. I have actually purchased from him 5 different times and highly recommend him.
As for the K72P-6, I don't have any experience with that particular cap. It might be a good choice. If you try it, please let us know your experience. You may have already seen it, but I refer you to this link for a good discussion of Russian caps.
http://www.diyaudio.com/forums/tubes-valves/115744-russian-pio-caps-should-i-use-them-2.html
I have found that, for a 1 uF K75, a 1 nF (0.001 uF) bypass cap is my favorite. I have tried a teflon (FT-1), a polystyrene (K71-7), and polypropylene (Amtrans AMCH). My personal choice is the polypropylene. I have a theory that you should bypass a cap with a smaller, but similar type of cap to get the most coherent combination.
Have fun playing with them. The K75 alone is probably too colored for most. But with the right bypass, it can be both rich and balanced.
Jac