Cary SLI-80 tweaks and improvements?

Hello all,

I have an older Cary SLI-80 that I'm trying to find a path forward to a wider sound stage and improved dynamics.  In comparing it to my Decware Taboo, yes, it has a boat-load more power available, however, the Decware has a much wider sound stage, better channel separation and decay from instruments like cymbals, compared to the Cary.  The channel separation is much better on the Decware and this is especially apparent with songs that feature heavy panning from left to right and back again.

The Cary is running vintage Bugle Boy 6922's, vintage Sylvania 6S7N's, and Ruby 6550's.  

I have been looking at a couple of different paths forward:

Moving to EL34's or another power tube?

Upgrading the internal capacitors such as upgrading to the F1 mod?

A combination of both?

Any other ideas to try to capture the performance of the Decware are welcomed.

Thank You!


Some of this can depend how old and what generation/model your SLI-80 is. If you don’t know, check the serial and call Cary and ask. There were a few nice changes/upgrades over the years and outside vendors who created their own series with upgrades, i.e. F1, and even those can be upgraded again. For example, is it a Base model or Signature model, are any of the factory upgrades applied over the years, i.e volume control installed, signature wiring yes/no, how old are those Ruby 6550s, etc. This depends on how you want to attack it, piecemeal -or- possibly go for the whole batch of common upgrades all at once (I recommend this approach, so worth it).

Many of us here could likely go on for pages here about all of the things to look for and try, dare I say send it to Cary to test and apply upgrades, or better yet find a really good local tech to test it. For example,, look over at the caps/age installed, test the tubes/transformers, and more - inside. A really good tech can quickly assess it and speed you forward fwiw. Good techs do this quite regularly. 

I owned a fully factor upgraded Signature, then had a local tech buddy help me discover more upgrades replacing caps again, a few diodes, better Silver wiring inside, then tried a few different quads of KT88s, various vintage input/driver tubes, and 6SN7s. I think upgrading to the really good coupling capacitors and [new] main output tube changes made the most notable differences to me in one shot. Get this - Cary actually bought my SLI-80 back from me for more than retail price to study the upgrades we did. The new owner was absolutely thrilled with it. Ended up going with a SLP-98 preamp istead and separate amps. That souped up SLI-80 was sweet, should have hung on to it actually. Again, mine was already a Signature model to begin with. Seriously, I’d just seek a great tech if you want to cut to the chase and start enjoying it more, sooner. It’s worth testing/upgrading if you can. Best of luck.

Thanks for the detailed reply.  Mine is not a Signature model.  By looking at the font on the top of the unit, it's probably more of a "first-generation' type.  What KT88's did you eventually land on?

I'm searching for a good local technician so hopefully I can fine someone that's not only competent, but not backed up 6 months!

I emailed Cary this morning to see the costs and turn-around time for the F1 upgrade.  We'll see what they have to say.

I emailed Cary this morning to see the costs and turn-around time for the F1 upgrade

I wish you good luck with that.

Your comparison achieved the results I would have predicted.  Cary is a swiss army knife with high power.  Decware keeps it very simple, touches the signal as little as possible, and stays lower power.  

I suggest instead of working on the Cary, you shop for more sensitive speakers and maybe even go SET.  I don't even do push pull any more.  I had a ZMA, it was excellent, but couldn't match an SET.  push pull is a compromise but many make it because it is better than SS and their speakers don't support SET.


I looked at changing speakers for a while, but I really like my present speakers, which are Vienna Acoustics.  I have looked at a pair of Omega bookshelves since they are more sensitive and almost bought a pair.  There isn't much else that I have seen that interests me and fits into my budget.  I also thought about picking up a set of those Klipsch RP-600 MII's since they're relatively cheap just to see if I like them.  I still might do that.

I almost think that I'll eventually land on a Decware Torii which should do enough of everything I want.  The just don't come up very often, though.  :\


Swiss army knife is my own term for amps that do everything.  The circuit gets complcated, lots of switches and selectors attached to it and each one degrades it a little.  You lose your tube magic and start sounding like a printed circuit board based SS amp.  

It isn't nearly as bad as a few other propular brands.  It is perhaps a the medium swiss army knife that you can carry in your pocket as opposed to the giant one with everything including a fork that just barely fits in the glove box.

I'd like to see a circuit diagram as there are quite a lot of components in the photos I'm seeing.  


In the hands of a very skilled tech, you can get a bit more out of the amp and make it more enjoyable with your current speakers. The stock model has the lower grade volume control getting in the way, limited coupling capacitors (may even be dried out), standard wiring to the binding posts, and clearly using limited tubes. I ran Gold Lyon KT88s in mine, and they were decent, not too bad. You could try PSVANE, and we did these in a buddy’s upgraded Jolida amp, they were very nice new.

btw, helped a buddy upgrade his VA speakers, the end result required woofer cone replacements and entire crossover replacements with help of Danny at GR research. In hindsight my friend should just have replaced the factory x-over parts with better parts a few levels up, and left the crossover design alone imo. We tried a simple parts upgrade because he was cheap, but it made a difference. Then the GR upgrade, which I felt was overboard. And, I’ve heard that amp with Klipsch RP600Ms, and would not waste your money IF you can simply get the same tech to replace crossover parts in your existing VAs instead. Just trying to save you money, and cut to the chase, a lot of hype out here imo.

Even if it takes a solid year to find and you have to drive/haul the gear 5hrs away to find the right tech, it can be worth it. Best of Luck.

A couple things here as I’ve owned the SLI-80 a couple times both upgraded F-1 varieties. It’s a great amp and IMO will never be confused sound wise with SS and has definitely has that tube magic with the right speakers. Duane, the upgraded volume control I believe you refer to is actually an input selector switch that Cary offers an upgrade from factory standard issue to Grayhill brand which was included in the F-1 Editions.

Cary still only lists these including the Grayhill switch. A local colleague did additional upgrades on mine beyond the std stuff Cary offers. The newer upgrades were better imo than the older F1 upgrades. The newer Mundorf caps really made a difference over the older Jensens too on my buddies 98 pre. He had both versions in his preamp too. I sold mine, will see I if I can find the name of the upgrades volume potentiometer etc. Cary does not offer it iirc. 


I received a reply from Cary.  It looks like their upgrades have expanded beyond what's on their website.  They now offer an upgraded choke as well as some Solan bypass caps that can be installed.  Also, the larger coupling caps are now Mundorf caps as decooney mentioned.  Mine must be a bit older since I have the Jensens in the kit.

I'm emailing the gentleman there for some clarification on a couple of items.

There's a local technician that I found that mostly works on vintage guitar tube amps that I have used to test my tubes as I come across them.  I'll see what his thoughts are if he wants to tackle this project.

What's funny about this thread is the amp sounds quite good, actually.  But since we can be a weird bunch and I think I must have been spoiled with the Decware, here I am chasing that last bit of detail.  


I have a couple of other questions:

1) When installing the 4 Hexfreds, do they just replace the standard diodes that are there, while retaining the tube rectifiers, or are they meant to replace the existing tube rectifiers all together?  The installation "diagram" doesn't say anything about this.

2) I can't seem to locate a Grayhill volume control pot mentioned anywhere such as a part number or anything on Cary's website.  Would you have that info, as well?


Thanks for all the replies and help, so far!

1) yes, you are replacing them as I understand it.  Best to ask Cary what they do.  Personally I like the tube rectifiers but I'm sorta old school in my thinking perhaps.  

2) Grayhil is the updated input selector switch, as pehare noted above.  

I'm not sure where my local tech sourced the volume control and he's long retired and out of all that now. Just doing the caps, input selector, silver wiring at the back to one set of inputs and possibly speaker terminal too can help.  

As noted, there is nothing wrong with the stock form amp, has it's own warmed signature the stock way too. The new/upgrades add a bit more transparency and detail IF that's what you are looking for. Some are NOT.  A personal taste imo.    I originally had the Jensen oilers in mine and later went to the Mundorf caps. The older-older gen1 version Jensen oilers should be replaced, they had some batches fail years back. This leaned many to try the newer Mundorfs that had different results most seem to like.  Best to go for it and listen, see if you like it or not.  

I actually like the tube rectifiers as well.  They just look cooler, in my opinion.  😎 

I was looking at this photo which shows the internally modified bits and it appears that it matches the diagram I have where the Hexfreds replace the existing standard cylindrical diodes.  It shows the rectifier tubes are still in place on this example:

Cary Audio SLI-80 Signature Stereo Tube Integrated Amplifier - The Music Room (

I can see what Cary has to say for clarification, just to make sure, though. 

Cary informed me that the hexfreds just replace the existing diodes and the tube rectifiers stay.


Also, does anybody know the plate voltage in these?  I can't find a stated value any where.  It would be helpful for trying different tubes.

I found the plate voltage for mine.  Measured it at 588v.  So for future reference, there it is.

Coincidentally I just got an email from Cary Direct about the SLI80, and in a review a customer is raving about the soundstage and the Hexfreds:

"I am currently a couple of weeks in with this great amplifier in my system. I am using it in mainly ultra-linear mode (but also like the triode option), driving Audiovector QR7se's. I have a Bluesound node acting as a streamer with a Chord Qutest DAC in the mix. Wow. This amp sings. I went with the Hexfred upgrade, but all else is based. The soundstage is incredible. The Cary team was also great with the purchase process, and the amplifier arrived less than a week after ordering. Very happy with this product."


Just for future reference, Cary emailed back a list of bias settings for the various tubes that will work:


EL-34 50mA

KT-77 50 mA

KT-88  75mA

6550 75 mA

KT-120 75mA - 80mA

Do not use KT-66's.

Woah hold up.  For the op:  DAC , cables and interconnects can make a large difference.

I have an older Cary dac for the exciter head phone amp.  It’s decent, but I’m not claiming It’s great. My point is that it sounds warm and smooth, but it in no way compares to the better DACs of today which gives huge stage..

and yes, certainly tubes can change the sound stage, but so do DACs and cables.