Vogue said:
I believe you're talking about a design like this:
http://www.briangt.com/gallery/album53
If so, you will need to take a close look at the specs of the tube.....
Magura 🙂
Just a plain tube ... aluminium 216 mm outer diameter and thickness 8mm - length approx 200 mm.
It's a standard tube .... proberbly not Blowtorch finish ... or design. But anyhow ...
Anyhow I think you know more about this ... this is also why I ask a lot of questions!
Vogue
It's a standard tube .... proberbly not Blowtorch finish ... or design. But anyhow ...
Anyhow I think you know more about this ... this is also why I ask a lot of questions!
Vogue
Vogue said:
Just to keep this thread reasonably on topic...if you need help drop me a line in private.
Magura 🙂
Consensus!
Let's build the preamp, using feedback from this thread, let's make the PCB's and start to build a transistor preamp as good as and probably better then the JC-2.
Kind regards
Kamskoma
Let's build the preamp, using feedback from this thread, let's make the PCB's and start to build a transistor preamp as good as and probably better then the JC-2.
Kind regards
Kamskoma
This is something I have to see!
Which JC-2? Parasound, Levinson, both?
Actually what you are heading toward is the JC-80, which received the 'preamp of the year' award in Japan, years ago. It is a good solid design, and with a few upgrades is OK in my book. Still, it sits in my closet so that I can use my zero global feedback CTC Blowtorch preamp, which sounds slightly better. Maybe someone has the schematics for the JC-80 that they can post here. It's OK, the design is more than 25 years old, now.
Which JC-2? Parasound, Levinson, both?Actually what you are heading toward is the JC-80, which received the 'preamp of the year' award in Japan, years ago. It is a good solid design, and with a few upgrades is OK in my book. Still, it sits in my closet so that I can use my zero global feedback CTC Blowtorch preamp, which sounds slightly better. Maybe someone has the schematics for the JC-80 that they can post here. It's OK, the design is more than 25 years old, now.
Why not this one http://www.ohbashoji.co.jp/support/discontinued/file/jc80
Or a modified JC-2 with a new PS
Kamskoma
Or a modified JC-2 with a new PS
Kamskoma
That is a JC-80, and it is only similar to a Levison JC-2 and also similar to the new Parasound JC-2 just coming out. It is a good solid feedback design, much like the original JC-2, but better.
Now, we need schematics, especially for the line amp. The phono stages are a throw away design at this time.
Now, we need schematics, especially for the line amp. The phono stages are a throw away design at this time.
In case you connect them properly, very well. Milled stair-step shape connection. Minimalized leak. Maybe I post picture next week.
Envelope!
If you use alu plates you have to treat them with some type of "alodine" just to get a non oxidizing surface, you also get a better conducting surface, it is a must.
Kamskoma
If you use alu plates you have to treat them with some type of "alodine" just to get a non oxidizing surface, you also get a better conducting surface, it is a must.
Kamskoma
It is difficult to make 1 piece box. That is for experts. Just use sheet metal aluminum, and you will be OK. Thick is better than thin. No magnetic materials.
RFI Tight Enclosures
Kamskoma
It is quite possible to make an enclosure from several plates that, for all practical purposes, is as good as a solid milled chassis. The thing to keep in mind is the relationship between leakage and the maximum aperture dimension. The leakage varies as the third power of the aperture, so it is vital to avoid slots or long gaps. There are several conductive glues or conductive elastomers that can be used to eliminate gaps between the plates. There are several companies, also, that make RFI gasketing material.
The other thing to remember is that RFI can enter an enclosure either via a radiated or conducted route. Closing the gaps will prevent radiated RFI, but conducted RFI (from any cable) can be even more of a problem. Mitigating this problem is usually accomplished by the use of ferrite beads or RFI filters that are built into the connectors. For example, most power entry modules contain an RFI filter, although its purpose is usually to prevent the escape of RFI out of the enclosure. However, the filter works well in the opposite mode.
With the widespread introduction of digital electronics and the FCC/CDE emissions requirements, there are lots of companies manufacturing RFI suppression devices, so there is quite a wide selection from which to choose.
Kamskoma
It is quite possible to make an enclosure from several plates that, for all practical purposes, is as good as a solid milled chassis. The thing to keep in mind is the relationship between leakage and the maximum aperture dimension. The leakage varies as the third power of the aperture, so it is vital to avoid slots or long gaps. There are several conductive glues or conductive elastomers that can be used to eliminate gaps between the plates. There are several companies, also, that make RFI gasketing material.
The other thing to remember is that RFI can enter an enclosure either via a radiated or conducted route. Closing the gaps will prevent radiated RFI, but conducted RFI (from any cable) can be even more of a problem. Mitigating this problem is usually accomplished by the use of ferrite beads or RFI filters that are built into the connectors. For example, most power entry modules contain an RFI filter, although its purpose is usually to prevent the escape of RFI out of the enclosure. However, the filter works well in the opposite mode.
With the widespread introduction of digital electronics and the FCC/CDE emissions requirements, there are lots of companies manufacturing RFI suppression devices, so there is quite a wide selection from which to choose.
Hmm, wouldn't graphite seals do the trick of closing any gap when making a box of sheets? You know, the kind used for gaskets and the like in high temperature environments.
Magura 🙂
Magura 🙂
Ok, so you're needing to build a chassis out of thick, solid aluminum in order to keep RF to acceptably low levels.
That leaves me wondering, what exactly do you plan on using to shield the interconnects that will be going into and out of this thing?
se
That leaves me wondering, what exactly do you plan on using to shield the interconnects that will be going into and out of this thing?
se
Steve,
this is just the point. In my case, instrumentation shielding box, there is only one input BNC connector connected galvanically on the surface of the box. Output is fiber optic cable.
If one let conductors get into box without their shield/screen connected on the box or HF feedthrough at least, the effect of electrical field shielding is lost.
this is just the point. In my case, instrumentation shielding box, there is only one input BNC connector connected galvanically on the surface of the box. Output is fiber optic cable.
If one let conductors get into box without their shield/screen connected on the box or HF feedthrough at least, the effect of electrical field shielding is lost.
Schematics!
Ok guys and dolls, let's go for the schematics, anybody?
JC-80 or a Blowtorch clone, schematics including PS.
Kamskoma
Ok guys and dolls, let's go for the schematics, anybody?
JC-80 or a Blowtorch clone, schematics including PS.
Kamskoma
Re: Schematics!
You can find pretty much the whole shebang in this thread...so back to page one 😉
Magura 🙂
kamskoma said:
You can find pretty much the whole shebang in this thread...so back to page one 😉
Magura 🙂
When I mentioned the JC-80, I was referring ONLY to the line stage. Everything else should be ignored, because better solutions have been posed on this thread, already. Please remember, the design itself is over 25 years old.
The line stage of the JC-80 is similar in overall topology to the CTC, but it uses negative feedback. Servos are essentially the same. Power supply buffering is essentially the same. It would be easier to make than the CTC.
The line stage of the JC-80 is similar in overall topology to the CTC, but it uses negative feedback. Servos are essentially the same. Power supply buffering is essentially the same. It would be easier to make than the CTC.
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