I did drive Wharfedale Linton Heritage speakers with the Crimson too. They are reportedly 90dB efficient and 6 ohm nominal impedance. Had gobs of power for those loudspeakers. Maybe 17 watts is all you need.
Peeking inside a Carver Crimson 275 Tube Amplifier
So, I just had to pop the hood on the Carver Crimson 275 tube amplifier. I was so curious as to how this little guy weighs so little and sounds so lovely.
Does the sound quality of this amp bear a relationship to the fact that there’s not too much going on in the unit? There are very few caps--from what this humble hobbyist can tell--in the signal chain. And, none of these caps are even what many would consider decent quality--i.e. they aren’t WIMA level, just generic. This amplifier beat out a PrimaLuna Dialogue HP (in my room/to my ears...much love for what PrimaLuna does). When I explored the innards of the PrimaLuna, it was cramped, busy and had so much going on--a way more complicated design.
Is it possible that Bob Carver, who many regard as a wily electronics expert, is able to truly tweak the sound by adding a resistor here or there, etc.? Surely all designers are doing this, but is he just really adroit at this? I wonder this because while some parts quality is very good to excellent, I was shocked to see the Suntan caps. They might be cheaper than some of the Dale resistors in the unit. I should note that Carver reportedly designed this amp and others similar with Tim de Paravicini--no slouch indeed!
I have described the sound of this amp as delicious. It’s that musical and good. But, as our esteemed member jjss [ @jjss ] pointed out in his review, he wondered if the sound quality could be improved further still. He detected a tiny amount of sheen here and there [I cannot recall his exact words.] even though he loved it like I do.
I may extract the two .22uF caps that look to be dealing with signal related to the 12at7 gain tubes and do a quick listening test.
- The layout is simple and clean looking. Unlike the larger monoblocks (that cost $10k), this model uses a PCB.
- The DC restorer circuit is nicely off to one side and out of the way. It doesn’t look all that complicated but I’m no electrical engineer. Why don’t more designers use this feature? It allows the power tubes to idle around 9.75w. Amazingly efficient.
- The amp has very good planned out ventilation and spacing. No parts are on top of each other.
- Most of the parts quality is good. There’s a host of Dale resistors, what look like Takmans, nice RCA jacks, heavy teflon hookup wire, and so on.
- Some of the parts quality is questionable. There’s some cheap Suntan (Hong Kong mfr.) film caps coupled to the power tubes and some no name caps linked to the gain signal tubes. I was not happy to see those, but I very much understand building stuff to a price point.
Does the sound quality of this amp bear a relationship to the fact that there’s not too much going on in the unit? There are very few caps--from what this humble hobbyist can tell--in the signal chain. And, none of these caps are even what many would consider decent quality--i.e. they aren’t WIMA level, just generic. This amplifier beat out a PrimaLuna Dialogue HP (in my room/to my ears...much love for what PrimaLuna does). When I explored the innards of the PrimaLuna, it was cramped, busy and had so much going on--a way more complicated design.
Is it possible that Bob Carver, who many regard as a wily electronics expert, is able to truly tweak the sound by adding a resistor here or there, etc.? Surely all designers are doing this, but is he just really adroit at this? I wonder this because while some parts quality is very good to excellent, I was shocked to see the Suntan caps. They might be cheaper than some of the Dale resistors in the unit. I should note that Carver reportedly designed this amp and others similar with Tim de Paravicini--no slouch indeed!
I have described the sound of this amp as delicious. It’s that musical and good. But, as our esteemed member jjss [ @jjss ] pointed out in his review, he wondered if the sound quality could be improved further still. He detected a tiny amount of sheen here and there [I cannot recall his exact words.] even though he loved it like I do.
I may extract the two .22uF caps that look to be dealing with signal related to the 12at7 gain tubes and do a quick listening test.
234 responses Add your response
Funky54, I think you are making a big assumption, which may be true or it may not be true. That assumption is that ASR's testing was accurate and that it actually had a Crimson 275. The models ASR tested did not have serial numbers. The build quality from pictures is not consumer grade or fit for resale. Did you know Wyred4Sound makes these amps for the Carver Corporation? They must be in on the scam too. Look, if the Company made material misrepresentations then that is terrible. But don't you, or the numerous folks piling on the ASR forum recognize how absurd this would be? It would be one thing to miss your specs by a bit. Here, if ASR is correct then the Crimson 275 only makes 22% of its specified output. The Crimson 275 drove Kef Blades at Axpona a few years back with pleasant results. Maybe they just love 17 watts of power to get them to sing. I suppose that's possible. I once had LS50s linked to a 300b SET and they sounded pretty good. |
We’ll let’s talk about what I would hear. The manufacturer of my speakers says 100 watts are to be seen as an absolute minimum and it’s highly recommended to be ran on 200 Watts. It’s easy to hear noticeable differences going from 100 and then 200 W with my speakers. So having been a carver fan and owning twin C-500’s vertically bi-amped, I toyed with buying 275s. Can you imagine how incredibly angry I would have been? He, the manufacturer, Mr. Carver, is saying his amps put out 75 watts… it’s not true.. but he’s not even close. He puts out something like 17 W. You’re telling me I should be just OK with that because it might sound nice on some efficient speakers? 17 is not 75. And hiding the fact by putting teeny weenie little tiny transformers under big gigantic covers is just fraudulent. |
I’m not disagreeing with you, perhaps the specs are inflated and I do not support that. The OP and others posting here say it’s a very good sounding amplifier, to me that means something. ASR seems to care little (If any) about how a product sounds. What do you hear? That’s the essential question. |
yep, sonics matter..but so does ability to drive a speaker… so no speaker, no music. The specs are useful in assessing current and future suitability to drive various speakers…. Having said that, i am guessing the Music Reference RM-10 , also a lightweight gives the Carver a run for the sonic money…..Modjeski like Carver a genius… |
I agree listening enjoyment is most important to our hobby. I’m no fan of ASR - they put listening dead last. But outright false claims by manufacturers can also damage the hobby. And I don’t see how these particular amps come close to hitting their power specifications, unless they can break the laws of physics or have a hidden plate amp under those transformer covers. I’m not a stickler for 1% THD being the "clipping" cutoff for power measurement, but it shouldn’t be pushed much more than a few %. |
Kinda silly.. doesn’t take an engineer to look up the transformer part number and see it’s only rated for 15 watts. . Doesn’t take an engineer to measure output at only 15 to 17 watts per channel.. pick on science nerds all you want. Why does the manual say the transformers are made from fictional steel from Greek mythology or Wolverine’s claws… no kidding right out of the manual. FROM CARVER, there it’s verified. |
Carver’s own specs: 19 lbs for a Crimson 275 rated @ 2x 75 Watts?? That’s ridiculously lightweight, for a tube amp. That puts it in the class of a console-pull EL84 amp pushing ~ 15 Watts a side. No amount of Bob Carver "magic tech" talk can make that go away from my mind. The higher-end Carver monos also weigh only 44 lbs a side and claim 350 Watts! That’s very concerningly over-light, for the tube powers involved. The Rogue Audio Atlas weighs 55 lbs, actually hits its rated 100 Watts x2, and costs roughly the same as a Crimson 275. The Rogue Apollos weigh 100 lbs per side, spec 250 Watts, and cost similar to the Carver monos. Hell, I have a pair of Heathkit W5 that EACH weigh over 20 lbs. These are 25 Watts/ch KIT amps from freaking 1959. Their manual publishes detailed power response curves under load, and they literally kick the crap out of what ASR measured for the modern-year Carver Crimson 275! They sound really sweet, too. |
Sad (And regrettable)? Yes. Surprising? No. I’ve visited that site in the past and was very disappointed with the content quality. They can’t even be thorough enough to be sure they have a true representative Carver amplifier. Yet can natter incessantly about conclusions. Real scientific method being practiced over there. I think not. Charles |
A little birdie told me that the amps subject of ASR's testing were, in fact, $600 kit amps--differing in quality from actual units sold with serial numbers. It doesn't come as a surprise that folks over at ASR believe they've uncovered a fraud. However, surprise element aside, isn't it ironic that those touting science so heavily in high end audio likely didn't do their testing scientifically? For the love of all things sacred....If you're going to test things "scientifically" can you at least (a) buy the unit from a licensed dealer; (b) note the serial number(s); (c) make sure you know what you are talking about before posting alleged scientific conclusions. What's sad to me is that after reading all 13 pages of the ASR forum thread on their uncovering of "fraud", the confidence in their opinions never budges--even after a reputable dealer chimed in to clear some things up. |
I read the Audiosciencereview site testing and forum posts on this amp. A couple of thoughts. Folks, especially those who tested it, seem very confident that the amp cannot make spec output, uses Edcor PT and/or OPTs, and is a fraud. The original testers of the amp on ASR admit they didn't have units with a serial number on them. Other posters provided pics from Bob Carver's amp camp, a la Nelson Pass type of thing, where you could build one using Edcors as shown in photos. The piling on continues for 13 pages. Will ASR test a genuine model with serial number? They promise it's coming and things drop off from there. Let's see. Lest I forget, I own this amp and feel it beat out (in my system) a Primaluna HP integrated weighing 55lbs. I personally never cared for Bob's marketing. But sound wise, I think this thing sounds great. Be careful out there. As Benjamin Disraeli said, "There are lies, damn lies, and statistics!" I'm not sure where this will end up on ASR or any site. I do, however, question how valid, comprehensive or meaningful some of this criticism is on the amp. I don't think I care enough to crack my amp open again to look at the transformers. Keep it coming! PS. I've heard some of the DAC stuff they love on ASR because "it measures so perfectly." I tried two of them. They sounded good--not great, not musical. Kind of like a stereo in a luxury car. I also wonder how a Fender Bassman would measure. I bet gobs of distortion. Thank goodness ASR doesn't supply bands with amps. :)
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@funky54, I'm curious to read the fire from other cites/posts. Can you put up some links?
fiesta75, Can you tell us why you believe the 275 is a disappointment? Did you/do you own one? What experience do you have with the amp? What is it about the amp that let you down?
I have no comment on the unit's power output in watts. I have 102dB sensitive speakers so I don't need much juice. Let it rip folks! Transparency is a great policy. Frank, looks like you have some things to answer! |
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The 275 is under scrutiny on at least four other audio forums as we speak. Interestingly on one, the negative comments are largely removed. I’m happy here we can have a warranted inquiry without censorship. I’m not sure why the forum mods are protecting truth on this other audio forum.. but the real measurements and specs are all over the internet like wild fire. Multiple sources sharing the same failures to meet published spec in epic proportion. As a previous fan and owner of Carver products I’m anxious to hear the other side. My confidence has waned and I’m becoming bias with facts that will be tough to refute or explain. |
@fmalitz Frank thank you for this response.. however I’d like for you to respond to why the 275 does not even come close to its specs? Why does an amp spec’d for 75 watts per channel only put out 17 wpc? Why are the transformer covers very large fake covers over very small transformers that are only capable of 15-18 wpc? I almost bought a 275. I am glad I did not, seeing how I know from experience that my speakers need at minimum 75 to 100wpc. Can you imagine how angry I would have been finding out it can only put out 17 wpc?
I visit Audiogon often but hardly ever post.. I was moved to post this question. I’d like an honest answer. |
@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. |
so jbh - would you please write a short post with specifics as to your passive components mod (sorry to make you repeat this), so that i can pass the info to my tech to replicate your successful minor surgery to the unit? i have my parts connexion account locked and loaded to order the caps etc etc!! thanks in advance! 🙏 |
I have a great Bob Carver system. My Magnepan 1.6 QR have bypassed factory crossovers. They are bi-amped by a pair of Carver 350 monoblocks (woofers) and one Carver 275 (tweeters) using a Marchand vacuum tube electronic crossover. The preamp is a Vacuum Tube Audio SP14 by Roy Mottard. (The monoblocks are early iterations of the 350 series and have red, “Crimson,” chassis, but are definitely 350 watts per channel.) |
@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. |
I am Frank Malitz, owner of the Bob Carver Company. I should be addressing capacitor and resistor questions. But, I would like to respond to phantom. here’s what he said about my company: "I used to own the Black Beauty, It ran very difficult speakers and can handle difficult loads, Unfortunately Bob carver setup Distributors globally and got everyone to buy and market the amps for some time and then dropped all the distributors within an instant. Nice Amps but the people running the company have no idea." 1) the Black beauty was made many years ago and has nothing whatsoever to do with Glass Audio Inc. doing business as the Bob Carver Company. 2) Bob and I started the Bob Carver Company on January 1, 2016. I took over ownership January 1, 2020. Bob remains as my chief designer and certainly one of my best friends; we speak weekly. EJ is my only partner and builds it all by hand in CA. 3) I have only expanded into Thailand, New Zealand and Australia. I have not set up distributors globally because we have never been able to meet the demand and still cannot to this day. All purchasers of my product will be forced to wait between two weeks and six weeks depending on the model although two of our three approved Internet resellers stock large quantities which makes it easier on us all. Phantom, I have never dumped a distributor. Let me explain what a distributor is: we have no distributors in the United States. We only sell through retailers. We do not sell directly to the public. In the world of audio, a distributor will stock inventory in a warehouse in larger quantities than a retailer. That distributor would sell to the local retailers in his country who are too small to buy directly from the manufacturer--a common scenario. 4) the only time that Bob set up distributors globally was for the Carver brand and they fired him 35 years ago so phantom is a little bit behind the times. Even Sunfire, which Bob opened after being fired by the Carver Company, did not have global distribution. 5) Bob is still honoring the warranty on in-warranty tube units that he sold before January 2016. When he bought the Carver name back, he covered all the warranties out of his pocket. It is not legally our responsibility to back up those units but we always help anyone with a problem as best we can. This is easy because there are no failures. We have no service department. I can remember one 350 failure and about four 275s with buzzing transformers due to a mistake made by our supplier in not following Bob’s design. This is over a 15 year period representing hundreds of units sold. Our warranty is 40 times longer on the tubes than McIntosh or Audio Research, on our point to point units and 20 times longer on our PCB models and ten times longer that Prima Luna who are smart people! We’ve sent out eight tubes in ten years. In my 55 years in the industry, I have never handled any product with this low a failure rate (In all honesty, I don’t recall a defective Bel Canto). 6) I do not think it’s appropriate for phantom to claim that I have no idea what I’m doing. Most people would be offended. If this response is too wordy and defensive, I hope you can understand. I spent my life in this industry trying to bring good sound to everybody at every price level, hosting trainings at 8:00pm in the middle of nowhere. Yet, according to phantom I have failed. Here’s a list of companies I’ve established, designed for or represented: (from my profile): Onkyo USA Integra (part of Onkyo USA) Yamaha (twice) SME Grace Supex Denon DCM a/d/s/ Meitner Museatex VPI Thorens Trinnov Pro-ject REL Counterpoint Vector Research Kenwood Audio Alchemy (twice) Acoustic Research (second launch) Dahlquist (second launch) Apogee (second launch) Sonus Faber Totem Acoustic (three times) Triad Loudspeakers (three times) Golden Tube Tandberg (second launch) Electrocompaniet Cambridge Audio Earthquake Sound ADA Artison Harmon International (incl JBL, Infinity, etc) ELAC Sunfire Carver Sennheiser Focal Klipsch M&K AudioControl Nordost Monster Cable Arcam and at my age, I can guarantee I’ve left some out!
Consultation Experience: Denon (tone arms and cartridges) Stax (designed their first close back headphone) Ortofon (phono cartridges) BES (loudspeakers and marketing) Thiel (product and marketing) Acoustic Research (product and marketing) Signet (electret headphones) MXR (third octave equalization) I’ve enjoyed every minute of it. Coolest job in the world! Almost.Sometimes, when I visit a forum, at the close of business, which is a rare occurrence because I own three companies and I’m 75 years old, I see a note like phantom’s and I wonder why I’m participating in this until the wee hours of the morning. But, the positive responses make it all worthwhile. I know some of you folks and you hopefully know I’m on the level. Come see me at the shows. I’m delighted to help anyone on any hifi topic and my phone number is published right on my website! I’m here for you seven days a week. |
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! |
@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. |
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. |
@jbhiller Thanks much for such a detailed and thoughtful response. Also enjoyed your comparison to the Elekit. Your impressions of the PL seemed to parallel mine but you used yours with far more speakers than did I. I love elegant solutions--and the 275 surely leans in that direction compared to the PL. Your caps are only going to sound better in time and I hope this amp is long term keeper for you! Thanks again. |
@jbhiller attempts at morning humor aside, a few points back to you 1 - went through your system pics... just love your room, the guitars hanging... that is a sweet place to be for sure, i can feel the positive vibes just seeing the photos... 👍👍👍 2 - also want to commend you on your spirit of positivity, enthusiasm and passion, and your willingness to tinker to learn and potentially improve already very good gear, ’make it all it can be’ - i don’t trust myself with a soldering iron to save my life, but i am so glad a fellow dedicated enthusiast like you is willing to climb the learning curve and share findings -- for all its faults and garbage, this is the a-gon forum at its very best... 3 - the carver amp is brilliantly conceived, bob carver has more than a little spark of genius, but clearly the crimson amp is built to a price point to make it commercially successful and sell at good volumes, so i can imagine some of the internal components can stand upgrading if the owner seeks a higher level of absolute performance, and is willing to pay for it ... that is no knock on carver (quite the contrary), it takes talent, serious talent to make affordable stuff sound so great, it requires knowing where spending $ makes a real difference, and where $ can be intelligently saved 4 - i know e j sarmento at w4s fairly well, he is a smart, very nice guy, a fellow enthusiast, and he of course builds these units for carver and frank m... i would think he would be very open to trying to incorporate potential mods commercially, but bear in mind he is the contract manufacturer -- bob c and frank m own the brand, and thus the right to ok development changes - no harm in reaching out to them though... jb, i really look forward to hearing your further observations on how your lightly modded 275 is improved as it has more playing time, and i will likely follow your lead on passive component upgrades... it is a killer app amp at its modest price point in stock form, and the thought of making it even better is exciting! |
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 |
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. :) |
@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
Cons
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. |
@jbhiller, I have to tell you that those proposed amplifier modifications/upgrades for a final product cost of 4500-5000.00 USD seems very reasonable and doable. This would be a high quality very good sounding tube amplifier with a price that is assessable for a fair number of people. @corelli +1 regarding the demeanor of this thread . Reminiscent of how this forum was when I joined about 12 years ago. Charles |
Wow. This thread is like a breath of fresh air. Gentleman posting really interesting and helpful information. Well done! @jbhiller Great job on the upgrade and pics. My OCD kicks in on these types of things so I can imagine some angst at removing the original caps without destroying the board. I have had time with a Primaluna HP integrated in the past but never heard the Crimson. Could you comment on how these two sound relative to each other? |
@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. |
@jbhiller , Your post "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. :)", You need to ask EJ Sarmento of W4S and Glass Audio America who is manufacturing the 275 about making an SE version of the Stereo 275, W4S makes hot-rodded versions of their gear so a Stereo 275 SE should be a shoe-in. |
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. |
'Johnny Hartman's "I Just Dropped by to Say Hello,"' @jbhiller, ahh yes! You have excellent taste. I'm not surprised by your improved sound quality. Not sure why some are skeptical about capacitor and resistor upgrades. In my experience they can be quite worthwhile if chosen wisely. Congratulations. Charles |
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. |
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. |
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. ;) |
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):
New Clarity CMRs (~$225 upgrade) + 4 Kiwame Resistors on the Coupling Caps:
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. |
