captainbeefheart

Nobody has said anything about it sounding terrible and nobody would have a problem if it was sold as a 15wpc amplifier. But selling a 15wpc amplifier as a 75wpc amplifier especially for the price is what the problem is. Add in the glued down parts, and lack of standard safety protocols and the Crimson doesn't look so appealing. $2500 is a lot for a basic 15wpc push pull amplifier.

No, I don't recall any experience with them.

That is why when Amir was testing the amplifiers the fast blow fuses would pop when testing over a specific power output, I think it was 27 watts. This is how they are avoiding transformer failures. Now it's possible they can claim the amplifier can produce 70 watts peak transient power for a very short duration and only in the midband, if not a short time period the fuse blows protecting the wimpy transformers.

All the square Russian PIO capacitors I have used for crossover networks were hermetically glass sealed. I have tried MBGO, MBGP, and KBGP If my memory is correct the third letter 'G' in the name type means that they are air tight hermetically glass sealed. The first letter 'K' is Aluminum foil where as 'M' is Metallized paper. The Second letter 'B' is paper insulation The fourth letter I can't remember, something to do with the type of case and or it being made specifically for "Boreal Climates"

Defects are one possible 'fault' mode, whatever defect in the film will be cleared during first use. Those small defect areas are more or less a short, this short current vaporizes the metal film causing a void and clearing the short. Other fault modes include over voltage conditions usually from short duration transients. This high potential over voltage causes a corona discharge effect or 'arc' like we discussed before, this arc current will vaporize the metal film creating a void again clearing the problem area. Over current and heat can also damage the capacitor. Every single time there is a fault and the metal film vaporizes making a void and clearing the problem area it effectively continues to reduce the surface area which subsequently lowers the capacitance/reactance which mathematically directly correlates to an increase in ESR. It makes sense if you think about it, you are effectively slowly reducing the overall surface area which directly relates to the amount of capacitance/reactance. From what I gathered the vast majority of faults over the lifetime of a capacitor is from over voltage transients. Small defects in the dielectric are present from manufacturing mostly and clear when used, it will rarely encounter that issue again in it's service life.

That's really not a bad idea, I wonder how much they will drop on the secondary market after the smoke settles. At the very least the first thing I would do is make it safe. 30 watt Edcor output transformers are $100 a pop, but for $200 and maybe an hour of soldering you can make this amp much better. I believe the power transformer is under sized as well, and if you upgrade the output transformers you might as well throw in a larger power transformer for another $100 putting you at a grand total of $300. The hardest part of changing output transformers is re-calculating the compensation networks but still easy done. I would like to have a closer look at this 'DC restorer circuit' during higher output level testing, I am willing to bet it hinders performance at the cost of increasing tube life. Honestly the way it was blowing fuses for Amir at such low power the DC restorer circuit will never come into function as the tubes require going into cutoff for the circuit to work. The tubes of course last so long with this amp because they are just loafing around low power and low bias with these amps, the 'restorer' circuit is a gimmick I am sure of it. The mismatch plate loads for the LTP phase inverter are there to hope for balanced sections and get somewhat close to symmetry but it without adjustment it's a crap shoot to get symmetry. The best option and easy to do is just remove the 20k tail resistor and use a constant current source, make both plate load resistors equal and the CCS will force symmetry no matter what tube you install, no adjustment ever needed for perfect symmetry. It would be optimal to regulate the power tube screen supplies so they don't sag under higher signals. Rearrange the current feedback by adding 1 more resistor and a potentiometer to give you variable damping with both negative and positive current feedback.

But who wants to be the first one to be injured or killed from something deadly like this? We don't know for certain if there has been any issues but assuming nothing can go wrong is not good engineering, you design things for worst case scenario especially where safety is concerned. I don't bend on this, performance is nothing compared to peoples safety. I'm far more concerned with the safety of this amplifier than the performance, if one of these amplifiers crossed my bench I wouldn't let it leave without grounding the chassis and rework the ground network. I have done it a million times with mostly guitar amplifiers but also many Vintage amplifiers that do not meet modern safety standards. I would never want to be responsible for injuring someone or worse, death.

Not a bad video, I have seen a lot worse. He should talk in terms of wattage but that's ok, I know he is specifically talking about the Fender amplifier but the part of the 12A*7 type tubes and the filament needs are incorrect. He says you need 150mA for each triode totaling 300mA per tube, this is correct for 6.3v with them in parallel but these tubes have a center tap and can run on 150mA total for both triodes with 12v across series connection of filaments. Wattage stays the same, no matter the connection each triode requires 945mW of power for a total of 1.89 watts per tube. Trivial in the context of this specific amplifier but I figured I would clarify. The replacement transformer schematic he pulled up that had two primary windings he is wrong about with 120v you only connect to one winding and not both. The paper even says directly on it for 120v connect the two primary windings together in parallel and for 240v connect the two primary windings in series. Third thing I would like to bring up is the fact that with a Class B amplifier like this one you cannot just use power tube idle current as the maximum plate current. That would be correct for a purely Class A amplifier, they are at maximum current during quiescent idle. With a Class B amplifier like this plate current will increase during the Class B portion of operation so drawing loadlines and calculating maximum plate current will give you a better idea of the B+ current rating you will want.

Are you not concerned with safety issues?

So far no official voice from the company has said anything I don't think. Jim Clark was rude complete with name calling about the whole situation and said specifications be damned the amp sounds nice. He claims to only compare sound and price. He completely misses the point of false advertising. So far the damage control has been really poor. I believe the company has already contacted their distributors as they all now say "Specifications subject to change without notice" which tells me they will either update the specifications which I think should certainly be done, or they will just leave that notice up and not change the specs in order to cover them legally. So far Frank and Jim have been nothing but shills on the matter failing to see the problem of grossly bloated specs to make more sales. First they held to their guns and claimed the amps make the rated power, now they have back tracked to specs be damned it's only about how good it sounds. The mental gymnastics are strong with these two, I don't know Jim but many that know Frank dislike him as he is so full of himself and seems to think he knows more than he does which never is a good look for anyone.

Congrats on your new speakers. Looks like you went with polypropylene capacitors and found out why many dislike them as they can be too bright with these speakers. If you are looking for the happy middle ground replace them all with Polyester capacitors, it will get you to where you want to be in regard to not as bright as the Polypropylene but not old and possibly out of spec original capacitors on the board you didn't touch. If you want to go for the absolute best right out the gate I would just go ahead and use paper in oil capacitors. They are really not that far removed from the Polyester cap sound, they tend to be just a bit smoother than Polyester. Stock capacitors from Klipsch is Polyester which is why they are #1 recommended. If you choose a Metallized Polyester type which is by far the most widely used I suggest up-rating the voltage handling in order to try and keep any sort of fault clearing from happening which makes them lose their capacitance and increase in ESR. Anything over 400v rating should be a good choice, I know many will say that's overkill but I'd rather be prudent to keep the caps as healthy as the day they were installed.

I have always had a soft spot for Art Deco. Thanks for posting, I forgot how amazing this building is.

I suppose that is a positive way to view the situation, but more denial than truth. Concept amps are 'innovative' which this amp is nothing of the sort. We have learned things over the years, one things is under bias isn't good, the more current you have the better the performance. Current feedback from the speaker is nothing new and it's not adjustable, I have been telling people the virtues of adjustable positive/negative current feedback from the speaker to adjust damping but this is not the case here. If you look at the frequency plot it is hardly flat, there is a boost in the low end to compensate for poor bass performance in the output transformer. Cleverly named 'DC restorer circuit' is a sliding bias scheme again not new. Now on paper if you were to draw this up you would expect the power output they claim, now that is if you use correctly sized power and output transformers, yes the power transformer is also grossly underrated for this design as well. I really think Bob designed this on paper to be a true 75 watt amplifier except someone in Corporate, most likely Frank Malitz grossly cut corners for profit. Now for people not in the know the transformers are by far the most expensive parts in a tube amplifier, so they skimped out on them to increase profits after they found out during the design stage that it sounds good enough to fool most people for long enough to rake in the dough. Let's put the power issue aside for one moment and I will 100% go with the notion it's a 'concept amp' and people love the sound and that's all that matters. There is one thing nobody should ever cheap out on and that is SAFETY. How do you explain away such gross disregard for safety in this product? Many of you have seen many products with only a two prong bipolar cable but if you look on the back it is Class 2 rated double insulated and sent to UL to be given a third party safety rating. If you do not design the device for double insulation Class 2 and you choose to for Class 1, the metal chassis/enclosure REQUIRES a solid safety earth connection for fault protection. It is there to blow the fuse in situations where something with lethal potentials fails and makes contact to the chassis, without the ground connection the chassis becomes 'hot' and you become burnt toast. The absolute worst part about this is they actually connect the chassis directly to the mains neutral on the primary via a resistor!! 😱 Many old houses and buildings have their Hot and Neutral reversed at the receptacle which is quite scary if you think about it, plug this amp into the wrong outlet and you have a hot 120Vac chassis you can get zapped from. Granted it's a 4.7Meg resistor that will limit current pretty severely but it's still a shock hazard and stupid design that would never meet a third party safety approval. Frank was never going pay for a third party safety approval anyway (big profits remember) so who cares about killing people. Although it's nice to spin the performance of this amplifier as positive there is absolutely zero excuse for blatant disregard to safety.

Specs are there for a reason and should not be fudged for sales with an excuse of 'we don't listen to sine waves on resistors' because that's just plain silly. RMS power is RMS power so list the accurate specifications for your amplifier if you are proud of it's performance and stand behind it knowing "it sounds good". Plenty of SET amps sound great but they don't advertise them as 75 watts per channel, they are listed honestly as 2 watts per channel and still sell. In the blink of an eye Music Direct says the Crimson 275 is no longer available for sale. And this very next thing I noticed is extremely important as an indication of what kind of business Frank is running, every other place that sells the Crimson 275 has added; "SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE" So they are still planning on selling this amplifier with the known bogus specifications but are covering their legal behinds with this very statement upon purchase. How scrupulous can you get? They should immediately CHANGE THE SPECIFICATIONS to exactly how the 275 tests out as and either leave the price and see if they still sell, or lower the price and blow them all out to save a little face in the game. Jim Clark acted like a complete child in the ASR forum. Of course we don't listen to sine waves with resistors Jim, but we do need some standardized method of testing specifications for both the service industry and also for consumers to compare apples to apples before making a purchase. I just cannot believe that was his stance after all this being a dealer, instead he should want to protect his customers and keep his product manufacturers honest. Hate to say it but most of us were not surprised at the test results, the weight of the amplifier was the red flag. What really took me by surprise was how cheap these amplifiers were made with serious safety concerns. Forget the amp not making rated output power. How do people feel about it not even making common safety protocols. If your device has a metal enclosure and is not a Class II double insulated design it needs to have the outside chassis connected to earth safety ground, no exceptions. To make this very serious matter even worse, they tie the neutral of the mains to the chassis by a resistor. What if your wiring is incorrect in the receptacle? You get a nice warm and fuzzy 120vac eye opener by putting the hot leg on the chassis. This thing is actually scary and I cannot believe it's even in production with all the glaring safety issues. I mean one single point failure could put over 600vdc onto the chassis and there is no protections against that? That's just plain crazy. Add in the glued in current meter and all the other cheapo crap inside and you have a dangerous $500 retail 15 watt per channel tube amplifier selling for almost $3,000. If anyone that purchased this amplifier is seriously considering returning it and is beyond their 30 day money back guarantee I wouldn't ask for a return because of the lower power output, but instead claim it breaks safety standards and is dangerous, make sure you are going to let them know you are writing to the better business bureau and other regulatory agencies over the safety issues concerning the equipment and they might be much quicker to give you your money back going this route.

"No less than 5 minutes" This is important, and as I said I run the amps at full rated output for at least 5 minutes often much longer to watch for thermal issues. As stated ratings are RMS unless otherwise stated in the specifications. Testing with sine waves at full bandwidth with no more than maximum specified distortion. I personally do not think they have a leg to stand on as their specifications are quite clear, they are deceiving the consumer to think the amplifier can produce 75 watts from 20Hz to 20kHz with no more than 1% THD. Quote from manual: "More than 75 Watts Per Channel, both channels driven at eight ohms, from 20Hz to 20kHz with no more than 1% total harmonic distortion. Distortion decreases at lower levels." This is deceptive because according to the industry standards of testing the amplifier cannot make the claimed specifications.

I have had many acquaintances over the years that love their Carver amplifiers but I will admit I have had the 'pleasure' of making many repairs from friends blowing them up. The problem was instability and not even from ES speakers, many of the Phase Linear amps would go bonkers on even slightly capacitive loads. I will give them credit, Bob was always putting out new service manuals with revisions to part values and such to make the amps more dependable. I have seen many burned spots on his PCB's. I would never go as far as to say Bob is a liar, he was just pushing the envelope of audio technology which comes at a cost of complexity and many revisions to get it correct. I think he has done very well up until this debacle with the Crimson 275 which is just plain sad to see a legend fall so far. Who knows if Bob is even replying, it's probably just Frank that made this mess and Jim has to follow suit to save face and make sales.

I can clear a few of your questions up. As for Amir worried about fuses his house was basically under water at the moment which is why it took him so long to do the review, it's not like he doesn't have 3A fuses more that he didn't want to go looking for them as stuff may be boxed up and all over the place. I myself keep spare fuses but 3A is the most common and I have run out of them often. All of the amps tested could make 75 watts of power, but only at 1kHz and with higher than 1% THD. The major problem with this amp is the fact they used an output transformer rated for 15 watts. That doesn't mean the transformer can't pass higher amplitudes at certain frequencies, like the standard 1kHz used for testing, what it does mean is that for the audio band it is rated for 15 watts, low frequency performance is directly related to the size of the transformer. That's the problem with the Crimson 275, it isn't anywhere near the specified bandwidth to power and distortion. An honest company goes by industry standard specifications. which is your rated output power should be for full bandwidth stated, at maximum distortion stated, and for RMS power into rated load for extended periods of time. So for 75 watts into 8 ohms you should be able to see on a scope a 34.3 volt peak waveform (sine wave) for all interested frequencies and this should not blow fuses. I can purposely clip amplifiers and not even blow fuses for honest amplifiers. You should be able to run a decent amplifier at rated maximum output for long periods. After I do major repairs I run the amplifier at it's full rated output into a dummy load for extended periods of time (hours) to make sure all is well. The Crimson 275 shouldn't be blowing fuses anywhere under 34.3v peak signals, it shouldn't even blow them when clipping either. Amir's testing is completely adequate to deduce this amplifier is a complete fraud. It's limited by the output transformer to being a high quality 15 watt amplifier regardless if it can produce 70 watts at 1kHz, that's not how you rate an amplifiers output power. This is where the confusion sets in, people not in the know see the amp can produce the power for short periods before blowing fuses but that is not how it should function, it should pass that waveform constantly into load at all interested frequencies (20Hz-20kHz).

I think some of the owners of these amps were hanging on to a sliver of hope this final test would show different results. There are going to be a lot of angry consumers looking for answers and refunds now, hoping the company bucks up and takes care of them on this. I really hope they don't deny these results and sweep this review under the rug with cease and desist orders from the court. Curious to hear from some of the owners in this group to see what they plan to do. I don't think I could personally sleep at night letting this company get away with this and even if I really liked the amplifier I would probably ask for a full refund, there are plenty of great amplifiers you can purchase or have custom made for $2500.

https://www.audiosciencereview.com/forum/index.php?threads/carver-crimson-275-review-tube-amp.29971/ Amir over at ASR finished up the review of the brand new out of box production unit and the results were actually more dismal than expected. I enjoyed the review of course and I am certain this amp sounds fine at <15 watts which is fine for Klipsch speakers, the issue is people purchased this under the guise it can produce 75 watts per channel cleanly into rated loads with published bandwidth and distortion and it doesn't. I could understand any owners frustration and not sure what I would do, probably try and return it if I paid full price honestly. NO SAFETY GROUND ON CHASSIS - Yikes!! Meter glued to frame is low class for this price point. Loose screw inside is scary for a brand new unit. Pretty bleak. If you purchase I high power tube amplifier make sure it weighs the part if it has output transformers.

He posted the review!! https://www.audiosciencereview.com/forum/index.php?reviews/

I will say that what these things CAN do that actually makes a difference is isolate ground loops, but that can be mitigated much easier. Nobody likes ground loops.

Pick a video on power conditioning and I will pick it apart if you like, much of what is said is maybe more 'misleading' at best. If the 'power conditioner' gives any advantage to whatever it's powering then all he would need to do is show difference in data between before and after at the output of the device. Say a preamp is plugged into the power conditioner, show a before and after noise floor measurement at the output of the preamp. Paul does a lot of talking but he never will quantify any objective data to prove without a doubt his devices improves anything, it's all subjective hoopla with tidbits of technical lingo to confuse a non engineer into making the wrong conclusion that they somehow need these 'conditioners' for their equipment. If you told the engineer that designed your top of the line high fidelity amplifier that you plug their gear into a power conditioner they will most likely be offended. They understand that your precious signal is nothing more than a modulated DC supply, and they go to great lengths to make sure that this DC supply is as perfect as can be no matter what is happening on the AC power input. Even if you had an absolutely perfect 120v 60Hz power signal what do you think happens when it passes through a rectifier? Your perfect sine wave turns into a nasty saw tooth wave full of odd harmonics because a rectifier is a grossly non-linear load. That's why all the important stuff happens AFTER the rectifier. I get it, the laymen isn't going to understand any of it, the people selling this stuff are really good at making you worry about things that are not there or do not matter. They are great at telling you very eloquently about the virtues but slow to show any actual relevant data of proof.

A few of my correspondents are into watching those PS audio videos of Paul, I can't stomach watching them myself as most of the information is wrong or misleading in order to sell their products. My understanding is your line quality becomes pointless with well designed equipment, we engineers understand that there are line fluctuations so we design around it. Also your average power supply will filter any noise out, they have a much more difficult job smoothing the 120Hz ripple currents as it's an ugly low frequency waveform full of nasties. Sensitive stages get regulated etc.. A 're-generator' would only be necessary where your line power has gross amounts of distortion (>10%) or worse has DC. These issues may make the power transformer work much harder which obviously isn't good but I have never seen a house with over 5% THD and if you have DC then you want to get that taken care of regardless of audio equipment as all your house appliances and electronics will suffer. The FCC makes laws where if your product is a highly non-linear load which can add distortion and pollute the mains they require filtering at the power input of the device. That's why you see switch mode power supplies like computer power supplies etc.. has all these common mode chokes and X and Y caps for common mode and normal mode noise suppression. PS Audio and many other power filter devices do the same thing, they are nothing more than passive filters. They may have an active filter type system by now which is much more effective in many regards but again if your equipment is designed well it's not needed, it's only needed by law if your device will pollute the grid. I keep large surge suppression breakers for each bus directly on the power distribution panel to keep line transients at bay for the entire house. These eventually accept all the energy they are going accept (typically MOV's) and should be replaced every 3-5 years depending how many transient events you receive on average. I advise before spending any money on anything have your power analyzed to see how clean and regulated it is. If it's fairly stable and <5% THD I wouldn't waste my money on any power products.

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