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    the safety precautions around high voltages.

Why can't I build my own ARC LS-5 or CJ PV-12?

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As far as the pv-12 the cap are the only thing special but you can use good polyprop or even teflon for big bucks . The circuit is not much more than text book the power supply regulator is advanced and was desigened about 30 years ago . the store will soon have great boxes to put them in . As for the ls-5 have not loked at the schematic .
 
As far as the pv-12 the cap are the only thing special but you can use good polyprop or even teflon for big bucks . The circuit is not much more than text book the power supply regulator is advanced and was desigened about 30 years ago . the store will soon have great boxes to put them in . As for the ls-5 have not loked at the schematic .

Thanks Triodethom. Does that mean I won't be able to duplicate the power supply regulator? What about the transformers? Any other problem with trying to build one?

Thanks...
Jim
 
Available from ARC DataBase website: ARCDB - LS5

It is a completely balanced circuit with all XLR connectors with no RCA single ended connector at all.

preamp schematic:
An externally hosted image should be here but it was not working when we last tested it.


power supply schematic:
An externally hosted image should be here but it was not working when we last tested it.

I don't know if I want balanced or not, I don't really understand it. But is there anything about this preamp a rookie like me should not be able to duplicate with patience? What about the transformers?

Thanks a lot...
Jim
 
There is nothing special or particularly worthwhile about either of these units. You can build better sounding clones by using better passive components and in particular a good quality switched attenuator for volume.

Nothing special about the transformers either. Any decent R-core with higher power rating will sound better than what the originals used.
 
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Jim , you can do anything you set your mind to do.

Your question is the very question I had asked myself when I first started out many many many moons ago and it is the very same question that drives my passion for this hobby back then and today !!!!

Just sayin'.


:cheers:

jer :)
 
Thanks Triodethom. Does that mean I won't be able to duplicate the power supply regulator? What about the transformers? Any other problem with trying to build one?

Thanks...
Jim
Sorry if I was misleading . the regulator not that hard to build built one from the schematic 27 years ago it not hard. If you can build off a schematic no problem . I like the aikido at tubecad.com much better than the two you chose even the cj act series is not much of a circuit just very expensive parts . The Aikido has circuit boards for sale making it a lot easier for a first time builder . The store here at diyaudio has boards for power supply and soon boxes to put the pre in .
 
Hi, thank you all. I picked these two just because of the acclaim they seem to receive from the tube audio crowd. I have a Conrad Johnson PV-5 mated to either a Marantz 8B or McIntosh MC-240 or MC-30s. I gathered this system in the 90s. I have just broken it out and love it, except that the sound is just too "thick" and "congested." I like the fat warm sound of individual instruments like jazz guitar or female voice, but for ensemble playing I would like it to be more clear, so when all the players in a jazz band kick in together it doesn't just sort of mush up and you could still hear individual instruments better. On the amp end I bought a SS amp to try cheaply, a B&K ST-140. It does sound slightly more clear, but not a lot. So I want to focus on the preamp. The PV-12 is supposed to be more neutral than my PV-5 but still with the CJ warmth, and people say ARC is a lot more neutral than CJ and the SP-8 and LS-5 are favored ARC preamps. Thus my choice of those.

I would dearly like to be educated about a better preamp to try and build that will give me tube liquidity and palpability, yet be more neutral and clear. Are there descriptions of the sonic character of the Aikido? I'm ready to jump in and start building different preamps til I get an understanding of what makes good sound that I like.

I was a bit surprised at how underwhelmed you all are at two preamps that are so acclaimed by tubophiles. Please do suggest any existing plans, boards, etc. that I might consider, and thank you all so much, I would not venture into this without you guys.

Jim
 
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With ALL Super-Fi equipment there will always be the "subjective" element. If you can borrow one to listen to and compare then you will soon find out what you like.

I've said it before -- When asked what Super-Fi is BEST, I answer, "Take your ears shopping". Come the end of the day you are buying what you are going to listen to.
 
Thanks Jer, I'm going to need that kind of encouragement :). I learned to solder when I discovered RC airplane flying/building. But soldering boards would be new. Maybe I should stick to point to point. But I'm ready to try.

Jim

If you are NEW to soldering I would try a simple circuit or two just to perfect your technique first. It's easy but there are a few tricks that you need to learn first.

You will already know that both surfaces need to be heated to the melting point of the solder, you will also know that both surfaces need to be clean of oxides and grease.

With electronics all you need to add to that simple technique is making sure that you don't overheat the components. Surprisingly a small iron can sometimes do more damage than a big iron. A big iron will heat and complete the joint very quickly. A smaller iron may take longer to heat the joint but will also heat the components above their failure temperature.
 
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KatieandDad, I certainly have experienced this. I used a Craftsman 45 watt pencil type. I have to admit I am never able to heat the components to the point they melt the solder, unless I touch some solder to the iron to act as a heat conductor. Often I end up just melting the solder into the junction between the iron and the parts. I guess this is bad but I'm not sure how to fix it. I certainly have melted the insulation on wire trying to get the wire hot enough to melt the solder. After my last post I started thinking who in this small town (Las Cruces, NM) I might ask to teach me to solder better. Maybe there is a community college class I could take.

I know this is going to be important if I am going to build my own preamp.

Jim
 
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I would just buy a bit of VEROBOARD and some wire and practice tinning the wire first and then making joints to the veroboard without melting the wires insulation.

Using solder to "wet" the tip is a good idea, just don't use too much because the flood of molten solder may jump tracks and cause short circuits .
 
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Use wire with teflon or irradiated PVC insulation that doesn't melt at the drop of a hat.. Could be you are doing nothing wrong, wire from the local Rat Shack has cheap PVC insulation that will melt during any attempt to tin it.

Tin the tip before soldering, heat the work while applying solder between the tip and that which you are soldering. Make sure the solder flows properly into the joint. When cool the joint should appear shiny if you are using lead solder. Eutectic solder 37/63 followed by non eutectic 40/60 generally gives great results. Kester is recommended. Lately I have started to avoid certain exotic (read expensive) lead solders targeted at audiophiles because the flux is too messy and makes far too much acrid smoke (I have asthma, and the flux is a serious irritant) - in terms of solder quality Kester is pretty hard to beat.

RoHS compliant solder is not required in the US, and while I use it at work from time to time I avoid it completely in home projects - none of which are slated to end in landfills any time soon. It's harder to achieve good solder joints with lead free solders, usually requires additional flux and makes a joint that never looks quite right - even when it is.
 
Thanks Jer, I'm going to need that kind of encouragement :). I learned to solder when I discovered RC airplane flying/building. But soldering boards would be new. Maybe I should stick to point to point. But I'm ready to try.

Jim

Soldering PCBs is really easy.

I do not use lead based solder, and have been using Johnson solder with Cardas flux. Used with the flux it flows just fine. I clean it up with alcohol and a toothbrush. I use a Hakko soldering station set at 800 degrees. I doubt I need to worry about tin whiskers in my tube amps....

Johnson Eutectic IA-423
Rosin Core FLUX RECOMMENDED
Diameter: 0.8mm
Melting Point: 423°F (217°C)
Silver 4.7%, Copper 1.7%, Tin 93.6%
 
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