Peeking inside a Carver Crimson 275 Tube Amplifier

Oz, what are you running now?  Aric or a Sachs? 

Guys, great comments above are making this thread!  

Yes, I fully realize that swapping out coupling caps can change things for the better, not at all, or for the worse. I would, however, like to do the experiment.  

I'll likely test two types--WIMA and ClarityCap CMRs.  I've used Audyn, Mundorf, VCap, Auricap, MultiCap, ClarityCap, and others in the past. 

I'm very tempted to call up Bob the man himself and ask him if I could visit him for an afternoon.  I bet I'd learn more in 3-4 hours than I have tinkering, reading, and assessing on my own.  

I'm very, very curious to see inside the 350 monos.  

From above..."Go ahead and chase your tail. Knock yourself out! Placebos and sugar pills will make it sound “sublime!""

Hmmm.... Not only is this not a very fun spirit you cast on this experiment, but I cannot agree. Why is it do you think Bob himself says the 275 gets about 75% of the sound of the 350 monos, which cost $5k each?

I think it’s because he worked really hard to keep cost down.

Take Don Sach’s post about upgrading the crossover in the Klipsch Cornwall IV. Roy Delgado likely knows a bit more than Don about speaker design. That doesn’t mean Don is wrong. It means Don can be right that better caps and resistors can improve the speaker. It also, arguably, means that Don’s upgraded crossover parts come to $900 retail, and if Klipsch bought those parts the build cost would certainly elevate and perhaps drive down demand.

I see this being the situation here. Bob Carver--the madman designer--put the 275 together with an eye on budget and end user price.

And finally, I have real confidence in my ears and listening. I’ll even admit that something expensive or "better" doesn’t sound better when it doesn’t. When I put VCap CUTFs in my Primaluna at the gain and phase split area they helped and it sounded better. When I added in Audyn True Coppers and some better Mundorfs in as coupling the power tube section and filtering power they didn’t do much if anything--but cost me money!  Wanting something to be better and actually making it better are different pieces.  

To each his own.  Thanks for dropping by!

Thank you Charles! 

Carver may have designed a pretty sweet integrated amp recently. His company put out some prototype pictures of the amp. Very cool. But it hasn’t materialized. 

Oz, I didn’t know you had 350 monos!  Can you describe the experience? 

Damn, I had no idea there are two of you--well sort of.  Sorry for the mistake!

Thank you for being the voice of reason Don!

jjss and Oz, thanks for making me laugh! 
I hope to do the surgery this week; waiting on parts. 

Status Update--

I have all of the power tube coupling caps in, which consist of 4 .68uF and 4 .1 uF Clarity CMR caps.  I have yet to touch the two .22uF caps near the gain/phase section of the circuit--arguably those could do more to signal preservation (I'm waiting on VCap CuTFs to arrive for that section).  

I also replaced the four resistors linked to the larger .68uF coupling caps with Kiwame 5watts, .39kohm and .36kohm.

I'll spare you the audiophile shopworn terms, and we are only 8 hours into break in.  

The new caps make things sound more relaxed and less tense.  I don't mean relaxed in the sense of more laid back, but rather less uptight.  I know this amplifier, very, very well.  With the cap swap, on Johnny Hartman's "I Just Dropped by to Say Hello," things don't sound as intense.  There's a bit of strain in those old caps (Suntan, brand anyone?).  

The Clarity's are clearly more detailed and it's easier to pick out the space around instruments and voices.  Piano sounds like the recording was voiced better--mics placed more correctly--when it's the same recording. 

The originals had more a feeling like we were driving at breakneck speeds and while we never drove off the guardrails, a sense that we could was there.  That made the amp exciting, and even though it was pretty darn smooth, I'm now seeing where it wasn't. 

Here's a summation--

Old/Suntan Caps (<$1 ea) and Bargain Resistors (~pennies):  

• Fun, exhilarating sound
  
• Big soundstage
  
• Powerful, fast
  
• Slight electronic hash on the top end and bass could be a touch more defined. 
  
• Overall, pretty nice gestalt. 
  

New Clarity CMRs (~$225 upgrade) + 4 Kiwame Resistors on the Coupling Caps: 

• Presentation seems at ease with more mature stature. 
  
• Things are relaxed--less uptight--but still dynamic.
  
• Detail is improved.
  
• Gone is the slight hash and tizzy sounds that can occur on the upper mids and highs. 
  
• Overall, things sound more elegant.  There's no loss in dynamics and power, while the sound of space around things makes things more seductive. 
  

We can debate confirmation bias or placebo effect etc.  I think I know my amp and my ears.  When tuning a guitar by ear you develop quite the sense of nuance for timber and when notes properly engage each other with overtones that naturally must come with when the frequencies of them ring together properly.  I'm not claiming I'm a golden ear--there's tons of stuff I cannot hear.  I can hear this.  And, I have done upgrades in the past where I readily admitted that the improvement was marginal or non existence or not worth it. 

From a subjective estimation perspective, I think this makes things sound 5-10% better and break-in has just begun.  

Notes for DIYers or Techs: 

Holy cow--I'd never desoldered lead free solder or at least like this.  I had my Hakko up to 890 degrees and there were times I couldn't melt the stuff.  I obviously used audio-dork solder (Cardas Eutectitc solder), which is way easier to work with and looks great.  

I actually had to carefully drill out some of the through holes on the PCB (not my first choice), as whatever is in the solder used by Wyred4Sound in construction is insane.  

There is virtually no room on the board to install these caps.  I was sensitive to size when selecting.  There are way larger options.  After break in, I'll be adding silicone to adhere the caps down, and I may add some bracing to hold them. Honestly though, they are so snugly fitted that they aren't moving now. 

This was a tough surgery for me.  I'm no hack, but I'm no pro either.  I've built one point to point EL34 amp, 3 kits, and done plenty of mods in the last 5 years.  This required a bit more patience.  

Carver could easily draw the board bigger as there's room in the chassis for this, which would accommodate bigger parts.  He has massive real estate on the board for the big resistors but virtually none to upgrade those Suntan caps.  

Now, I cannot wait to do the VCaps and get through equipment break in and subjective break in.  

PS. Voltages measured better with the new caps too--for the objectives out there!  There were spots where it looked like some DC was slipping through a cap on its output.  Not much, but it was there.  None with the Clarity Caps.

Many more hours of listening to go though.  I'm happy.   

Blasphemy--I know.... The VCap CuTFs arrived as I was only <12 hours into coupling cap break in, and I just moved forward. I don't want to wait weeks to go back into this amp again. 

The VCaps are in and there is a much bigger improvement swapping out the literally pea sized .22uF caps hooked to the DC phase inverter output to 12AT7 gain tubes (or at least that's how I read the board (again--I'm no pro).  

We are looking at a $500 modification total.  I'd project the Company would have to charge an extra $1500 to do this.  It sounds glorious.  

I hope the VCaps get better not worse.  I know Chris specifies up to 400 hours break in.  I'm not hearing that any is needed. So if it stayed here I'd be happy.  

Bob Carver, if you're listening, how about we collaborate on a Signature Edition of the 275?  Woahhhh, where's my humility.  Get back to your day job dude and let Bob work his magic. :)

One more EARLY listening note....

On Walter Wolfman Washington's "Lost Mind" from the album "My Future is My Past" (opening track): 

The opening soliloquy where he's pouring a glass of bourbon (presumably) sounds creepily authentic. I can hear the room he's in much more.  I had to listen to it many times out of curiosity and pleasure. 

The acoustic guitar now sounds to recorded properly. Before I thought it was buried a bit too much and not defined enough.  Now it's right there. 

Let's hope these caps don't make anything sound worse--especially poorly recorded stuff. ;)

FYI--I'm actually considering setting up a swap out station for testing the .22 caps hooked to the phase and gain area of the circuit.  The listening tests could prove to be worthwhile at getting this little guy to his full potential for me.  Or, I'd drive myself crazy. 

Clarity CMRs are a wonderful cap though. They really are.  

jjss, I think you deserve MVP of Audiogon's forums!  You have great knowledge, are a team player, and oh-so-hilarious!  

I used to be single malt guy.  Now bourbon and a touch of the green scene.  

But, Sir, (assuming you are a sir), this was a tricky little upgrade!  I would take 2X the time if I was doing this on someone else's amp!  

I actually called a woodworking friend to see about making a sub-unit plinth so I'd have more room.  

For photo of the patient post surgery
https://systems.audiogon.com/systems/9364

Charles, you are a guy that I've always wanted to have a beer or coffee with!

Most of the folks who are skeptical lack experience in doing these things.  I think Don Sach's word is valuable and it is without question he has such experience in spades.  

This little Carver amp is so lovely.  I'm quite pleased. 

@klh007 ,  That's a brilliant idea.  Here's what I would think could be viable--

1.  Lighted Meter
2.  Add Balanced Input option
3.  Upgrade gain and coupling caps
4.  Upgrade key resistors
5.  Use Leaded Solder
6.  Enlarge PCB slightly to accommodate caps--there's plenty of space in the chassis.
7.  Add more substantial feet

I'm thinking that would increase the price of entry by $1500-2000.  From a business perspective, it would get the cost into the $4500-$5000 range, and I don't think it would step on the market for their 350 monos at $5k each because not everyone wants or needs that power.  I have 100dB efficiency speakers in a sizable room (at least to me).  I need one amp to do its best.  I couldn't use the power of the monos if I tried. 

@corelli, 

Sure, I'll give it a try--remember, these are my ears, my room and my gear. 

First off, I love what PrimaLuna does and stands for.  I had a wonderful experience with them.  I love what Kevin Deal does.  He's a good guy with tons of knowledge.  I think he's a tremendously positive businessman and a lover of all things hifi. The PrimaLuna is a fantastic build and sounding amp.  The remotes are to die for.  (Speaking of which, my remote had issues and they ultimately gave me a new one ($250) for free even though I was well past warranty expiration. 

I really loved the PL when it powered more modern loudspeaker designs--KEF LS50s, PSB Imagine T3s and T2s, Dynaudio, Golden Ear, hmmm...what else, oh, B&W.  I'm sure over the years I heard others.  Never a bad match with any stuff I had or heard it with.    

Disclaimer--I have not heard the PL EVO range. 

The PL I had was the Dialogue HP.  That thing could seemingly power anything!  It was built like a tank.  The construction is super.  It is really gold standard on point-to-point, layout, clean build, etc.  I wouldn't want to service one or go back in one, as there is little room in the bigger models' chassis.  I felt like a surgeon in there.   

Pros to PL

• Build quality; good to great parts quality.
  
• Power
• Ease of use/maintenance 

• Tube rolling paradise
  
• Can drive and sound good with most stuff on the market (so long as it's not paired with something crazy)
  
• Dealer and customer service are IMPECCABLE.  They are like Manley Labs--you're almost family.
• Pleasant sound that doesn't offend.

Cons

• It weighs a ton (at least the HP I had).  Moving a 60lb amp is no fun. 
• Aesthetics.  I never cared for how it looked (this is entirely subjective).  The casework is awesome, but wasn't my cup of tea. It looks clunky to me. Others like it. Who cares? It's my silly view. 
• Not the last word on detail, air, sweetness, and so on.  I think it's the equivalent of going to a really nice restaurant that has continental fare--you can find something you'll like and it will generally please everyone and offend no one. 

In my system, the PL sounded BIG (I have efficient speakers), bold, pleasant, and generally musical.  Imaging was good. Bass was large. However, compared to the 275, the sound was thicker, denser.  The 275 is sweeter, substantially more holographic, clearer, more delineated without being hyper detailed or analytical.  I've never really understood how to use the PRAT description but I suppose it would fit.  The 275 boogies.  It swings.  It's sweeter, creamier, but has more air too.  

I just go for what I hear and what wins in my personal shootouts.  Maybe this will help--- I built a highly upgraded Elekit 300B amp (see Herb Reichert's reviews on it--it's pretty amazing).  When I had the PL, I would go back and forth between the PL and the 300B.  The 300B gave me water like clarity and rich detail.  But, as Ralph of Atmasphere correctly taught me on these forums, the 300B has little distortion at very very low wattage--once you start getting up to like 30% of its power, it starts distorting substantial.  The PL gave me balls and bombast--also a killer remote, tons of inputs, and tube rolling fun. 

When I got the 275, I ultimately stopped using the PL.  And, here's what was surprising to me--I used the 300 B a bit less. Why? I asked.  I think the answer is the 275 has a healthy dose of clarity, sweetness and space with holographic images.

Note--I'm not saying the 275 is better than the 300B, but I use the 275 way more. 

When I started messing around with the PL, I was never really able to tweak it to make it sound like what I thought was missing or what I was after.  Again it was a great sounding amp.  With the 275, I thought it fit my taste better for long term.  So I sold the PL.  Someone out there has a PL with VCap CuTFs on the two gain tubes.  :)

I think the 275 is about 75-80% stock of where the amp could be, but I'd defer to Mr. Carver for sure.  

Our esteemed member JJSS bought one and tried it about the time I got mine.  He has some killer gear, and great ears/experience.  He liked it much but felt there was just a bit of sheen or haze on top--I think he said he might be nit picking though.  I agreed. 

So I cracked it open.  My jaw hit the ground when I saw these.  https://www.suntan.com.hk/Plastic-Film-Capacitors/TS02.html.  Not because I think you have to have boutique or hi end parts to sound good, but because the amp sounded pretty darn great with inexpensive caps that I think are below good quality WIMA, AMtrans, and so on.  So I though, King Bob Carver's circuit and know how was squeezing everything out of those mediocre-at-best caps.  How would it sound with legitimate caps?  By the way, the physical size of the original caps in the 275 is almost laughable.  The .22uFs on the signal/phase section are no bigger than my pinky finger nail--actually smaller. 

I'm inclined to tweak via a cap, resistor, or tube before going after a $1K power cord or interconnects--just me.  I have decent cables, but none costs more than $200, maybe $300.  

Finally, keep in mind that I'm running Klipsch Cornwall IVs. I just don't know how this amp would sound with modern, less efficient designs.  I would expect it would sound great. Who knows!?  It's got balls. 

Also, Bob is a genius.  The PL would heat my room. The 275 weighs 18lbs or so, I can lift it with one hand, and it never puts out noticeable heat.  I think Mr. Carver admitted he lifted and tweaked the DC restorer circuit from 1950s television design.  It idles those big KT120s at 9 watts or something insane. It's not a gimmick. It works, saves energy, less heat, and your tubes last longer.  

Oh, one more thing-- the user gets to set the bias (sooooo easy--do not be bashful) on the 275.  I run mine around 70, which produces a big soundstage and images.  

Thanks guys!  Yes, I don't get the negativity out there.  When I'm on guitar forums, it's soooo rare to hear someone tell another their view is stupid or they don't know what they're doing, etc.  In guitar world, for instance, techs set the gold standard on how strings should be wound and say do not wind them more than 2-3 turns max (or something)--YET they admit guys like BBKing wound the living crap out of his strings and no one ever said, Hey BB sounds like his intonation is off and he's constantly re-tuning.  There is more than one way to skin a cat. :)

Check out the pic in my virtual system (last one) of the original caps.  You'll see I used a Phillips screw driver head from my impact driver to show the scale.  It's shocking. https://systems.audiogon.com/systems/9364

jjss,  thank you Sir.  You are always doing good on these forums.  I for one have learned much from you.  I also like how you are open minded.  For example, I saw you picked up a Devialet integrated.  I like that you are not diametrically opposed to something just because you typically like lots of tubes.  

I did reach out to Frank.  I keep in touch with him a bit here and there.  I'm going to have lunch with him soon.  He lives in Chicagoland, like me.   I want to be careful not to give them too many opinions--lest they think I'm a charlatan or a know it all.  I do, however, think they could expand their product line.  There's a BIG gap between the $2800 275 and the $10k 350 monos.  

There are pics and a press release out there concerning a slick integrated they might be bringing to market.  

@corelli, I'm happy that my words helped at all.  

The PL is such a great product.  I'd add a big caveat:  Perhaps the PL is just too warm, big and dark for my system.  With the exception of my CD transport (which I rarely even use) I have nary a transistor in my system.  In other words, the PL might be a great fit for folks who have no other tubes in their system.  I'm not sure. 

I've been running the system 12 hours on and then 12 hours off.  The caps are opening up a bit more in the midrange and bass.  The high treble sounds about the same to me.  

I'm hoping the Clarity Caps and the VCap CuTFs mate well. So far so good.  

Quite honestly, I wish I could buy the 275 in a kit form where they sell me the chassis, transformers (power and output), and then I source the rest.  I say this because I cannot help but wonder what $50 of premium resistors and the very few small electrolytic capacitors would do.  

In fact, I'd love it if I could buy a new PCB from Wyred4Sound and mod it up completely, and then compare it to a stock model in A/B.

I'm about 70 hours into the VCaps and ClarityCaps.  

Everything sounds wonderful.  

An update on the differences between the stock Suntan brand caps and the new VCap CuTF and ClarityCaps---

With the stock caps, I had a massive soundstage; nicely holographic.  

With the new caps, the soundstage is just as big but the things going on are more focused without losing that holographic nature.  There's an added composure to the sound.  Things were little less organized before, but that was quite pleasurable given the overall picture.  Now, however, I feel as though I didn't give up the size of the picture while detail and definition increased.  Very cool. 

One thing about the size of the soundstage did increase; that is the depth of the performance.  It was good before. I heard depth on many recordings that made me smile. Now, I'm just hearing more of it, across more recordings.

I'll stop the reviews and updates now as things are settling in nicely.  All the best to those who chimed in!

@fmalitz, Hope all is well with you!  Your curriculum vitae is impressive indeed!  Thanks for dropping by these humble parts.  

I trust you know, from my correspondence and previous phone call or two, that I respect everything you, EJ, and Bob have done and are doing.  

All the best!  

@tomic601,thank you Sir!  I really enjoy learning, listening, tweaking and the journey.  It is a passion and a hobby after all. 

@jjss49, 

Sure thing.  

1. Output Coupling Caps:  

Four (4) .68uF 630v ClarityCap CMR
Four (4) .1uF 630v ClarityCap CMR

Available at PartsConnexion.

2.  2 Caps on Pre/Gain Tubes.  Note, I don't have a schematic so I'm taking my best guess as to what caps ore on the signal input side of things. 

Available at VCap. 

Two (2) .22uF V-Cap CuTF 300v (matched to at least 5% or lower)

3.  Resistors 

Two (2) 36k ohm (36kR) 5watt. Kiwame
Two (2) 39k ohm (39kR) 5 watt Kiwame

Available at PartsConnexion. 

***********

Some notes:  

If I did this again, I might use VCap ODAMs throughout.  They are so amazing.  ClarityCaps are very good to excellent too and I adore their sound as well.  ODAMs can sound better than even the VCap CuTF to me. 

Your tech is probably better and smarter than I.  But, those two sets of 36k and 39k resistors right in the middle of the board are placed counterintuively.  They do not seem to be symmetrically placed to the circuit.  Even though I took photos in case I needed to see the original layout, I still installed one channel's 36k and 39k resistors incorrectly--I swapped them.  Well, that channel was super faint as an extra 3k ohm of resistance (I had a 39k where a 36k should go) made the output too low.  Takeaway--be sure to follow exactly how they are in there to begin with.  It's easy to do one side/channel and mirror it on the other, which is incorrect.  You won't blow anything up, but it won't work right and you'll know it.  

Here's a photo from my virtual system for your tech. https://systems.audiogon.com/systems/9364#&gid=1&pid=7

PS--There's no need to duplicate exactly what I did.  Any decent cap will be an upgrade over the cheap, generic caps that were in there.  

There's a couple of giant Dale dark grey/black resistors on the input side of things.  I suppose you could look at Mills, Ohmite, etc.