Carver Raven 350 Amps


Has anyone heard these amps?
They supposedly can produce 350 watts per channel which in my opinion is remarkable for a tube amp. I have the Atma-Sphere M-60’s 3.3 and I love their tube sound.

But I am curious, Bob has made some very interesting products through the years.

ozzy
ozzy
It is remarkable.  Looking forward to hearing some listening impressions. 
grannyring,

So, you have heard it? I can't seem to find any reviews for it.

ozzy
I have the Crimson 350's, used them to power my Ulfberht speakers. Very nice tube amps, but I went with BHK 300's for more power. The Carvers are an interesting design that run the tubes very cool, they only get lukewarm even after hours of use. They have adjustable feedback to change the tone of the amp, from a more solid-state sound to a more traditional "tubey" sound.
If I did not need the extra watts in my setup, I would have stuck with the Carvers.
No, I have not heard them and was only confirming the remarkable nature of his designs. 
jeffery, out of curiosity, why did you feel you need so much (more) power for a 99dB sensitivity speakers? They look like incredible animals.
33heffery,

Yes, I am curious also. With the Carvers stated 350 watt/ch that should be more than enough power. 

Perhaps the Carver did not have enough bass compared to the PS BHK 300?
Please explain more.

ozzy
I heard them driving a pair of his speakers in a very large room at the Capital Audiofest.
Very nice sounding amps!
erj1963,

Thanks I wish I could hear them.

P.S. I still own the Carver M400 cube amp.

ozzy
My listening room absorbs sound like a sponge, so I have to crank up the volume quite a bit to get the concert-hall levels that I like. The Carvers sound great, but would run out of gas before getting to those levels. The BHKs have no problem with this. In terms of sound quality, the amps are pretty much even, with the Carvers having a bit more sweetness in the midrange.

The Ulfberhts are sensitve speakers but they do enjoy being hooked to powerful amps. Bass does indeed benefit from this. They take on an effortless quality when driven by large amps.
333jeffery,

Thank you for the reply.

ozzy
Well I have not found much info about these amps on the internet and it looks like not much in the way of Audiogon users either.

ozzy
bobcarvercorp.com

Carver tube amplifiers are very similar to his earlier VTA/Cherry 180s and 305s with the exception of the transformers and tube complements so those old reviews are relevant. This is a tube amplifier for those who don't like messing around with tube amplifiers. 

I've had my 180s going on six years and the only power tube issue I've had was the glass bottle on one tube seemed loose on its base even though its bias was maintained. I purchased six new tubes expecting to hear years of degradation and there was no obvious audible difference so I replaced the one tube and put the old set back in. I did roll the input tubes to pairs of Psvanes which resulted in a slightly more refined and open presentation.

A few months after their initial biasing the tubes needed a minor adjustment and have held for all these years. All six tubes are biased at the same time.  

These KT88 tubed 180s are driving a pair of Avalon Acoustics Eidolons which are a difficult load with a sensitivity of 87dB and a nominal impedance of 4 ohms 3.6 minimum and recommended amplifier power of 50-500 watts. We often listen at realistic volume levels that would begin to congest my linear solid state amplifiers and have never needed more power. In an email Bob Carver suggested using KT120 for added power and a slightly different presentation but there's just no point.

So how do they sound? With the adjustable feedback its really up to you. 

What your not getting: Heat. Fancy casework. A jive assed limited non transferable warrantee. Regular power tube replacement intervals. Odd order distortion from a hybrid solid state design. Degenerating printed wire boards with tube sockets! Individual bias adjustments. And worst of all no tube cage, damn.

By the way I think BHK stands for Bascome H. King who wrote a review of Bob Carvers tube amplifiers for Tone Audio. Don't forget to bone up on the Carver amplifier challenge.

m-db,

Thank you so much for your reply.
Have you ever heard the Atma-Sphere M-60 amps?
I like their sound, just don't know how they would compare to the Carvers.

ozzy
Funny you should ask as I have owned both Atma M-60 amp (with Vcaps and Caddock resistors) and currently own the Carver Cherry 180 mono blocks (Vcap output coupling caps and Gold Point stepped attenuator instead of the stock volume pot).  It is the precursor to 200 watt precursor to the Crimson and uses KT88 tubes.  The Carver tube amp is a remarkable tube amp.  It drove all of my speakers without ever clipping including the relatively inefficient Raidho D2.1 and D1.  Compared to the Atma M-60, the Carver is much more dynamic, has more precise imaging and deeper soundstage, although slightly less wide soundstage than the M-60, which has more diffuse imaging and soundstage.  As far as bass dynamics and extension, the Carver is hands down better and can drive almost any speaker out there. The M-60 requires careful speaker matching because of its OTL design and can sound very loose in the bass if you don't mate it with the right speaker. I would say the M-60 has a smoother, albeit more bland midrange.  The M-60 has hands down the most extended crystalline smooth high frequencies I have ever heard from any amp, solid or tube. My experience is based on stock tubes for both amps.

One thing I didn't like about the M-60 was its reliability.  Within 6 months of ownership (bought brand new), 3 output tubes failed with a dramatic POP sound from the speakers every time a tube blew itself.  I didn't like power transformer hum and tube hiss either.  The Carvers are essentially dead silent unless you have your ear a foot away from the power transformer in a ultra quiet room. Then you will hear a very low level hum. It's as quiet if not quieter than the solid state amps I own.  I never heard any tube hiss from the Carvers.
dracule1,

Well thank you for that comparison. It is very appreciated.
The newer version of the M-60's (the Mk3.3) is supposed to have taken care of most of the previous problems and the sound quality is said to have been greatly improved. Although, I can't tell since this the only unit(s) I have owned.  

I have only had one output tube fail in more than a year of operation. Dam Russians...
I'm also crossing over at 80hz and using some very (DIY) high efficiency flat line 8 ohm speakers. The M-60 meter barely moves.

But, I would like to try in the future some Martin Logan or Magnapan speakers and I know that I will need different amps to use with them.
So the Carver is on my short list.

ozzy

Ozzy, just realize that all manufacturers claim every new version is significantly better than the older version ;)

You shouldn't have any output tube failure in the first year of operation. I have owned the Carver amp for 8 years now with zero output tube failure.

I think crossing over the speaker at 80 Hz and letting the M-60 handle everything above is a very wise decision.  I have a 2 way speaker that is relatively efficient (89-90 dB) with lowest impedance 5.8 Ohm at crossover, mostly >8 ohm.  I was told by Atmasphere this shouldn't be a problem, but the bass was just too loose for my taste.

The Carvers should have no problem with Maggies.
I've been wanting to hear the Carver on my Magnepan 3.7i's.
dracule1,

I have heard from others that the Carver Raven 350 has a severe drop off in the higher frequencies. I am concerned about that. Can you comment more about that?

Thanks, ozzy
Ozzy, That has never been my experience with any of Bob's tube amps (I've heard the 350 and Silver 700 monster as well.). 

Context is very important.  What was the preamp, source, and speakers used to evaluate the 350 that showed "severe" drop off of the higher frequencies?  Were the tubes in the 350 stock?  The stock Shuguang KT88 are on the bright side in my opinion compared to the for example the Golden Lion K88 reissues, which are more natural sounding but can sound a little recessed in the highs.  Did the person who evaluated amp make sure the tubes were functioning normally?

Good thing about tube amps is that you can roll tubes and suit the sound to your taste to a certain degree.
dracule 1,

So you think the Carvers 350's have a decent top end?
Even the review of the 305 hints about a darken sound.

ozzy
Ozzy, it depends on which amp you’re comparing the Carver’s to and what your preferences are. Are you referring to the review by J. Valin? His reference amps are fast SS amps, I believe. In that context, I’m not surprised by Valin’s assessment. There is a way to significantly improve the sound of the 350’s without spending too much money. You can replace the stock built in volume pots with a mono stepped attenuators from DACT, Gold Point (I have them in my amp), etc. The Gold Points should cost you less than $200 (I have extra set of new Gold Points if you are interested). You can also replace the stock coupling caps with Vcap, Jupiter, or Duelund caps. You’ll need 4 of the 0.22 uF caps (you’ll need to verify values). They’re low value caps so shouldn’t cost arm and a leg. If you go with the tin foil Vcaps (I have them in my amp), you’ll pay around $400. You’ll hear more transparency/detail, increased dynamics, and more extension in the high and low frequencies. These upgrades are well worth the money, and you’ll never think they are "dark" sounding.
dracule 1,

Thank you for your help. I need to find some place to audition them.

ozzy
Glad to have helped.  Good luck.  Let us know what you decided on.
I have a set of the 305s and don’t find them dark at all.
Rig:
Legacy Aeris with Wavelet DSP/preamp & Oppo 105
Only driving 300 hZ+

To be fair, the Aeris are revealing and the AMT tweet/super are what I’d called prominent in the stage. Not overly forward but very revealing.

I can’t speak to how well they handle bass as I’ve never used mine for anything below 300 hZ.

I’m selling my 305s only because the Wavelet has a hard time with many tube amps and do not work with any SET amps.
Bummer as the Carvers have an incredible stage and great clarity (with switch set for less feedback) for a tube amp.
Scott
Well I went ahead an ordered a Carver Raven 350. Not quite sure how long it will take to get it though.

ozzy
Glad you ordered the 350.  If you want to take the 350s to another level, try the mods I suggested.  You won't be disappointed.
Ok, thanks. I am looking forward to trying them. BTW, I did talk to Bob Carver.

Can you recommend speakers for the Bob Carver Raven 350?
I like 60-80’s rock and perhaps some jazz and more recent music.
I must admit at times I do like to crank it up...

I have (2) JL Audio Fathoms F-113 subs with an electronic crossover in my Preamp (DEQX). So the speakers would not have to handle much below 80hz.

I have owned Legacy Focus, Eggleston Works Andra 2, Von Schweikert and a few others. Nowadays I would prefer less bulky, less boxy speakers.

I just listened to the new Focal Kanta 2. It had a good mid range and soundstage but the little 6.5 woofers were having trouble in the bass. However, with my subs that probably wouldn’t be a problem. I did like the way they looked.

I also just listened to the Magnapan 3.7i’s and was sorely disappointed. As most agree they are not rock music speakers. I knew they wouldn’t do the lower end but I was surprised how much they lacked in dynamics.

ozzy
How about Bob's new ALS speakers? It's only 5" wide and 5" depth, but about 7 feet tall, so very small foot print.  You already have subs, so you won't need to pay for the subs that come with the ALS.  It will play close to 110 +dB with the 350's (ALS can handle 120+ dB). It's dynamic as hell and soundstage and imaging are one of, if not, the best I've come across.  You can dial in the speakers to your room because the crossover has controls for treble, midrange, and upper bass balance.  Bob designed the ALS with 350's in mind.
dracule1,

Definitely Bob's speakers would be the right choice. However, they are a bit too $$$ high. So, I'm looking for other options.

ozzy
You might want to audition these:
https://totemacoustic.com/en/element-fire
https://totemacoustic.com/en/element-earth
The midrange/woofer driver don't need crossover, so it can be very dynamic.  They may be in your price range.  I have a friend who has very good ears and really likes them.
Also Proac speakers are very dynamic speakers.  If you can find a dealer, I'd lug your amplifier over and test the speakers with your amp.  Or the dealer may actually let to audition them at home.
Thanks, I’ll check them out.

My present DIY speakers consist of one Aurum Cantus G-1 Ribbon tweeter and one 7" ScanSpeak woofer. I used Mundorf SGO caps, Janzen Inductors and Path Audio resistors. They are crossing over to 2 JL Audio Subs at 80hz.

So, I would like speakers to have enough surface area to reflect a large soundstage but not necessarily deep bass. That’s why I thought of the Magnapan. And... I also want them to look cool or unique.

ozzy
Then I suggest you check out the 2-way stand mounts from Proac and Totem.
Just talked to Bob and he says my Raven 350 amps should be shipping this week.

ozzy
Great! First thing you'll need to do after turning on your amp is check the adjustable bias.  Start with withwhat Bob recommends. From there, Increasing bias will make thing sound warmer and more upfront, while decreasing bias will sound leaner with better sound stage and imaging.
Thanks, interesting. What about the different ohm taps in the back? Should I experiment with these also?

ozzy
would love a pair of these. damn money is always the trouble.
too expensive, by the time im ready for these, company will be no more.
im happy with my sunfire.

let us know how they sound, etc etc, we expect a full report, review on your thoughts the sound with different music, switches, bias, etc etc.
arcticdeth,

I hear ya, cost is always the factor. The units were shipped and then were requested to be returned back to the sender. So, I hope this gets straightened out.

ozzy
Ozzy, which tap you use depends on the impedance of your speakers.  Unless you have really low impedance speakers like 1-2 ohm Apogees, the 8 ohm tap usually sounds better than 4 ohm tap. Bob's tube amps do have a 1 ohm tap.  But there is no hard rule regarding this, so you can experiment.  
Well it looks like I should get the Carver Raven 350's today.

ozzy
I went up to see Bob Carver yesterday and listen to the 350’s. After extended listening (the 350’s attached to his ALS speakers) I ended up purchasing a set of the Crimson 350 amplifiers. Bob and Jordan were both very gracious with their time and open and honest with the questions I asked. The listening included A/B testing with the amplifier I am replacing. 

Jordan is very knowledgeable about the products and actively involved with Bob in the development of new products, he has obviously spent a large amount of time with Bob learning what he has done and how he has done it.  Jordan was able to answer 90% of the questions I asked as well as help me understand the things I was hearing.

Bob offered to sign the amplifiers and I elected to have him personalize the signature.  I understand the personalization negatively impacts the value of the amplifiers, but it makes them more valuable to me.

This is the first tube amplifier I have owned and look forward to learning and experimenting with it. I hope I have the opportunity to go and talk to Bob and Jordan again after I have a few months under my belt with the amplifiers.
erichgs,

Did you bring the Carver amps home? 

ozzy
Yes, brought them home with me yesterday. Have you received yours?
@ozzy I just saw your Atma's up for sale and messaged you on your System. Please disregard as I just saw this thread and got my answer. Congrats on your new amps and just curious, you just spent all the time building your speakers why the decision to change?
jond,

I'm a rebel... 
No, I like the sound of Planar and Electrostatic speakers but I know my current amps wouldn't work with them. It will be hard to part with my Atma-Sphere amps though because they sound so good.

ozzy 
ozzy that's cool so what planars or electrostatics are on your radar? With that much tube wattage you could pretty much drive anything.
jond,

There are many including the Sanders, Magnapan, and the Martin Logan. All are difficult loads to drive.

ozzy
Question:

I have noticed considerable hiss coming from my speakers with the Carver amps. When I turn off my preamp the hiss goes away.
So, I’m thinking that the hiss is not coming from the amps but from the preamp or other upstream components.

My DEQX preamp has adjustable input/output settings that have not reduced the hiss. There are also internal jumpers to increase/decrease the preamp output but at this time I have not changed them.

I do not hear this hiss when I use my Atma-Sphere amps.

erichgs, dracue 1, or others, any suggestions?

ozzy
@ozzy 

Are the Atma-Sphere amps entirely quite (put your ear right up next to the tweeter on the driven speaker and see if you can hear any hiss)?   The gain on the Carver 350 is 30db while the gain on the M-60 is 20db.  Do you hear the hiss if you set the carver volume knob to 2/3 (not sure if this knob is volume (output stage) or gain (input stage))?

 I am no expert but did just spend two weeks researching and troubleshooting a hiss/buzz issue in the amp the Carvers are replacing and from everything I read if you remove the inputs (in many cases the recommendation was to short the inputs) and noise goes away it is almost certainly not an issue with the amplifiers.  The trick then is to find the offending electronics.  I didn't know this up front and ended up spending hours of trying different things before finally just isolating the amplifier entirely on a single outlet circuit with all the other breakers in the house turned off and the inputs on the amp shorted only to get the same buzz.

Since you have already determined unplugging the pre-amp stops the hum, maybe start by eliminating the pre-amp and driving the carvers from your sources one at a time and see if one has a buzz while the others don't.

Erich
@ozzy 

I sent an email to Jordan asking about the volume control and he replied that it is on the input stage.  I believe this would mean it impacts both gain and volume.

Erich