I owned a LS7 when it first came out. I wouldn't spend the money for a couple reasons. Not that they demand a lot of money today, but modifying it will reduce its value. I never thought it was all that good of a preamp to begin with; it wasn't horrible but there were many preamps that were much better at the time and one being a solid state, the LS3 was a much better piece. I'd suggest unload it and look for something different altogether.
Hate to keep bringing up this preamp but it's a tuff one to beat. A ModWright SWL 9.0 SE will walk all over your LS7 no matter what you do to it, and you'll be money ahead. I owned the SWL for awhile so I do know this preamp as well.
Modifying it might reduce its resale value, but if you intend to keep it for awhile you will be pleasantly surprised by the improvement after replacing the stock REL caps and also the Wima filtering caps on the power rails. I did this to an old ARC PH2 and was amazed. I was going to sell it for beans, but after modifications it has become my MM phono stage of choice.
For this application I wouldn't stretch for V-Caps. Infinicap is now Dynamicap-- which at least offers the consistency of being ARC's current cap supplier. Or try MIT PPFXS or ClarityCap MR or ESA.
Hi eddy, Replacing the coupling caps can make a very noticeable different (agree with Dave of Clarity caps) and the V cap OIMP you're considering are very worthwhile upgrades. The cost of those caps represent good value. I'd do this upgrade if I were you. I used these caps in a Quicksilver preamplifier(replaced original MIT caps) in the past with a very fine outcome. Charles,
I agree with DG. MIT makes caps that sound good, mainly the RTX (styrene and tin) and PPFXS (polypropylene and tin). Before spending big bucks, you might want to try some smaller valued caps in your system, and see what works in your system. Some caps sound brighter than others, and that may sound good in your system. In your system. Can't repeat that too often. In your system.
Some caps may sound so bad that you think of giving up listening. I'm serious. And if you've just spent big bucks ... well, you just might.
I would begin with MIT (above) and Relcap Teflons. Then see.
A LS7 no matter what you do to it is going to outshine a MW SWL 9.0SE. It's not just a cap upgrade it needs. I tried NOS tubes in mine and etc. it just wasn't a great design, was short lived and the LS8 wasn't much better... short lived too I recall. The LS2b was much better or look for a LS15 if you want to stay with ARC. I'm guessing no one else on this thread owns or owned one.
After I sold my LS3 I went to a Sonic Frontiers SFL 1 next which is a more musical unit. You can sell your LS7 and probably buy a much better preamp for not much more if any more.
If if you are going to keep it and try the caps I'd suggest keeping the caps in it and just add small bypass caps on them. I used to own the schematic but gave it to the guy that bought mine, so I'm sure you can get your hands on one. Assuming you know what you're doing? If not I'd have a tech with mod experience do the work or you might have a mess then it's worthless.
If considering vcaps, which are quite pricey, I would concur with adg101 and consider bypassing, particularly with this preamp. It’s going to improve for sure but the LS7 is really not worth spending too much on for upgrades, diminishing returns would really come into play sooner rather than later. I would focus on a better linestage more than upgrading eddy1. just MHO.
Hi Tubegroover, I'm not familiar with this particular ARC Line Stage and I'll defer to your assessment. You believe that 50.00 USD for the V cap OIMP isn't a good value upgrade? These caps were very beneficial in my older Quicksilver preamplifier. Is the LS7 that unworthy? Thanks, Charles,
I hear you, 50.00 for the OIMP caps really isn't the overriding consideration but as adg101 points out and I concur, this particular preamp isn't really worth spending too much time and money on. It's an entry level pre and IMHO and experience with ARC pre-amps not worth it. I would concur with adg101 and focus on something better which I feel would yield a better outcome in time and money spent. The bottom line is that you can't make a silk purse out of a sow's ear and I feel that is the case here. In any case don't spend TOO much eddy1 whatever you decide.
Whatever you decide to do don't underestimate the amount of time it will take to break in the new capacitors especially in a coupling capacitor application. V caps and others can take well over 100 hrs (I usually burn them in on a bench for 200hrs+ before installing them)
The ARC LS-7 is an ideal line stage to upgrade. I upgraded mine with the help of two long time Audio Research employees / friends in their spare time around 10 years ago. One was Ward Fiebiger an ARC engineer who has since passed away. The other was a since retired ARC service tech who worked there for many years. The power cord was replaced with a Furutech gold plated IEC ( used with audiophile grade power cord) , Two (2) 4 mf 425 V Stealth brand coupling caps ( mounted on underside of circuit board) replaced the stock caps. Steath brand (sourced from Peter Montcrief owner of Wonder caps) bypasses were also used ( mounted on top side of board). The stock ( V1-V4) 6922 Sovtek tubes were replaced with 1960’s Amperex 7308’s ( NOS). The two power supply caps were replaced with higher value ( low ESR) Mundorf caps 680uf and 220uf . The 680 uf electrolytic power supply capacitor was bypassed with a 2 mf reference grade V Cap ( mounted on underside of circuit board). Another smaller value teflon cap was used as well for bypassing the Mundorf 220 uf electrolytic capacitor. The rectifier stage was upgraded with Schottky zero recovery diodes. The power transformer in this modified line stage remained stock. The opamp in the power regular stage was replaced with a discrete Burson V5. Damping material was added to the border of the top cover ( underside). A 100K Goldpoint brand stepped attenuator replaced the stock Alps brand gain control. The chassis was damped ( isodamp) and the stock tube sockets were replaced with ARC gold plated sockets. The stock rubber ARC feet were replaced with brass still points. The unit sits on a 2D Sieismic sink for isolation. This line stage is currently used with an ARC VS 115 amp ( using Vandersteen 3A signature loudspeakers) with outstanding playback resolution. The sound stage is deep and very wide with a lush top end and excellent mid and low end bass. Parts cost was pricey ( around 2 grand as I recall) but worth every penny and essentially turned the LS-7 into a small chassis single ended Reference Line stage.