Before you sign on for expensive mods, why not start with some Vibrapod cones and isolators
. I use Vibrapods under much of my gear, and I just put a special arrangement of Vibrapods under my turntable which has catapulted its performance to the next level.
For as little as $56 and no shop time, you could find out how far the Vibrapods take you where you want to go. See here
Disclaimer: I have no financial interest in Vibrapod; I've been an enthusiastic customer for over a dozen years, and they sometimes still surprise me.
Tubes that are tested for low noise might be the place to start. This would be a "plug and play" mod requiring only the effort to locate and purchase the tubes. But that romance and euphony might just be a product of noisy/micro phonic tubes. You won't know until you try.
Both caps and resistors will likely increase resolution and lower perceived noise floor. Retaining the tonal balance with these upgrades is a delicate balancing act. Most caps I've dealt with increase brightness to some degree, usually this can be adjusted for elsewhere in the system.
Modding power supplies may be helpful as well, particularly with the transients. I'm upgrading my Cayin's phono pre bridge rectifiers with HEXFRED's and bypassing the electrolytic caps with film caps next week, should have some answers soon. I'm looking for increased transient behavior, specifically more slam.
If you do go the modding route, just remember you can always undo the changes. I've also found modding to be the most interesting aspect of this hobby, really amazing sonic upgrades here! Endlessly replacing components is way too costly and relatively boring.
Mods are the way to go if you have some guts and soldering skills! Practice on cheaper pieces, gradually working your way up to more expensive components.
T bone, just looked at your system, like it! Also looks like you're comfortable with a fair amount of DIY.
The Jadis pre is nice, some VH Audio V-Caps, or better yet, some Duelund copper foil caps (depending on voltage ratings) should both give you what you're looking for. Others may have other cap suggestions, but the two caps mentioned above have to be on anyone's list of primo caps.
The Texas Components Vishay nude resistors (TX2575) are reportedly the best (I'll be making this upgrade soon to the Cayin). The Jadis is mostly point to point wiring which should makes cap and resistor upgrades easier.
Internal wiring would be my last upgrade, I like Mundorf Silver/Gold. Many others to choose from. NOS tubes and different isolation schemes may also prove very worthwhile.
Replace the rectifier(s)(whether a bridge or individual diodes) with soft recovery IXYS FREDs or CREE SiC Schottkys:(http://www.partsconnexion.com/catalog/semiconductors.html), and rewire internals with a good cable, like Kimber KCAG, going to a star ground with what would be the negative conductor and placing small ferrite beads on the positive conductors, at the source ends. Be certain your wiring is run tightly against the chassis, and(as much as possible) tucked in the bends along the outside of the chassis.
T_bone, if you have an older piece that you are wanting to update, the first thing to do is make sure that its actually working right first. To that end replacing the filter caps is the most important thing to do. You can get a lot of the aluminum can style caps from tubesandmore.com
Its not likely that improved resistors will be a whole lot quieter, but they will sound better. If you change coupling caps, which is where you will hear the most improvement, its a good idea to keep the following in mind: You can get better bass with larger caps, but you will pay a price in transparency and if the RC time constant associated with the cap is lower than that of the power supply low frequency pole, you will do your self a disservice. So I would stick with stock values for the most part.
Going to HEXFREDs is a nice touch although tube rectifiers are often lower noise. However, the higher output voltage that you get from semiconductors might allow you to install a high voltage regulation scheme. If you can do that, you will be instantly rewarded as long as the result is a B+ that is at least as high as stock! There used to be a device called the VB408 that was a high voltage regulator, very nicely suited for tube work. If you regulate, thats where you get the nice low noise floor.
Don't make a rat's nest of the insides. Keep your layout neat, with minimal wiring. It is a good idea to use a star-grounding technique and avoid using the chassis as ground. Its not OK even if the original manufacturer did it. That will help you get low noise too.
Thanks to all so far for responding.
Sns, it indeed is the Jadis I am thinking of working on. I am not nearly as comfortable with DIY as I would like to be.
Atmasphere, thanks for chiming in. The pre is a Jadis JP80, and it sounds wonderful as is, but I can hear where it is a bit off the mark vs other things I have had in my systems so want to try that. Without having schematics, I am a bit worried about going in myself (actually, with schematics, I am a bit worried about going in myself), but in this thread I am trying to learn which approaches will get me what I want. The pre has a separate power supply, which is beefy, and I have never felt it to be lacking. I think it is perhaps the main strength of the pre. I do not know how it is regulated. The newer versions are tube-rectified. At some point in the past, the power supply was SS. According to Arthur Salvatore's website, that started in 1990 and lasted a few years. Mine is a single-digit serial number, which would suggest it was before Jadis went SS, but since the aluminum cylinders in the back of the PS have covered tops, and I have not looked under the deck, I do not know if they are caps or completely enclosed tubes (and I am too much of a circuitry innards neophyte to have any confidence about what I see other than transformers, glowing tubes, resistors, and clearly marked caps (and, of course, I can usually tell what wire is)). Are "filter caps" the output coupling caps? And last question, would you suggest using a small cap in parallel as a shunt cap, as some do?
The "filter caps" are in the power supply. If you can still find Black Gate/Rubycon caps in the exact value that you've got in your pre now: They'd be a much higher performance replacement than the originals. I absolutely agree with Atmasphere- If your pre has tube rectification: Ignore my suggestion to go to FREDs.
I've investigated replacing the electrolytics in my Cayin power supply with a better electrolytic. Problem is the Black Gates/Rubycons are too low voltage rating (at least I've not found a source for higher voltage) for use in power supplies. I suspect he probably has decent electrolytics in his power supply, likely some better model of Nichicon, bypassing/shunt with film caps may be his best bet. I'm going this route in my power supply.
I believe coupling caps are the biggest bang for the buck, sonically speaking, these should be somewhere near the signal tubes. Not a job for the novice, find an experienced tech.
Have you thought of adding a power conditioner to your system? This made a big difference in my system.
There's some gear that responds extremely well to balanced AC. Had a SFL tube preamp that was a completely different beast when given 60/60.
I have a power conditioner that i have only ever used for my CD player (which I was using to isolate the other pieces from the CD player (which worked quite well). I can try it out to see what happens if I plug in only the low-wattage stuff (pre, phono, TT). Pretty soon you guys will talk me out of doing anything to it...
IMO/IME its a Bad Idea to bypass coupling caps. The result is smearing. The more resolution your system has, the more you hear it. On low resolution systems it may sound like that cap got speeded up a little.
Your best shot is to put in the best coupling cap that you can.
If the power supply does not have the tube visible in plain sight, then its not there. A can over the tube would overheat it!
If you decide that you really want to tinker with this preamp yourself, **do yourself a huge favor**: go out and buy a kit from PAIA.com or bottlehead, build it up and make it work. It should look like it was built by an expert inside. Seriously, this is important because you can get in over your head very quickly modding things! There can be shock and fire hazards, both to yourself and others, plus in the real world probably only about 5% of the total modified units ever wind up being better than stock- in the other 95% the mod is a destructive act.
After you have built the kit, look into how it is built and see if you can mod that to do better. If not, don't attempt it on something that came ready-built! Above all though, this is supposed to fun. Don't loose sight of that either.
Atmasphere has it right, start modding with something less valuable. You build up your skills on the cheaper stuff, as you become more skilled you become more confident in working on the more valuable pieces. Read some basic electronics books and ask questions at some of the more technically based audio forums.
You shouldn't be scared to start modding, it can pay off in sonics that fullfill your needs. You just have to understand the hazzards of modifying, nothing is fullproof.
I'm not sure I agree with Atmasphere that only 5% of mods are better, up to now I would have to put my success rate at aprox. 75%, YMMV. Doing you're homework prior to diving in is critical. Also, some equipment is not amenable to modding, the manufacturer may have already used premium parts and/or the voicing may already be optimized. I suspect a coupling cap upgrade in your Jadis will give you what you're looking for.
Atmasphere and Sns, thanks much for the comments, and the warnings. In any case, I had already planned on doing a Bottlehead pre (then changing caps, then adding shunts), to see what it would sound like, before touching the Jadis. Part of it an education issue, part of it a safety issue.
Feet- Isopods , sorbothane, Vibrapods, LAT
Chassis damping- Soundcoat
Electrolytics(power supply)- Blackgate, F&T, RDE
Coupling (output) caps-Mundorf gold, silver, ZN
Good tech to get proper direction on caps, optimize wiring scheme,etc.