Carver Raven 350 Review (Tube Amp)

[AndreaT]

Wasteful product: what is the amount of watts/h it requires to generate such a copious distortion? Like many other myths, it banks on the idea that the past was better than the present, and we deviated from some golden era when we went “solid state”. I own a pair of Dynaco ST-35 (one original, one clone): the enjoyment of Music is superior with my old Krell 300i, and light years ahead with any of the Hypex class D amplifiers. A complex Symphony like Mahler’s Third does benefit from the low noise and low distortion of modern amp design and their higher dynamic range.

 

[DavidEdwinAston]

Street cred, yo.

Yo, unless you haul them around the"hood" with you, how you gonna get street cred?

 

[restorer-john]

It would be helpful to give us a total noise figure in dBV or

the 5w at is at 4ohms? so 4.4721V?
so ~13dBV so the total noise is at -75,5dBV?

83.476dB with respect to 5W@4R is 270uV of noise, or 0.27mV.

 

[pma]

83.476dB with respect to 5W@4R is 270uV of noise, or 0.27mV.

Hi John, my maths says 299uV, anyway, 270 or 299 uV of hum/noise, both is too much.

 

[SIY]

Hard to say. The tubes themselves make a big difference in sound quality. Companies like GE and Raytheon used to make tubes for industrial applications like oscilloscopes and you wanted maximum quality. Nowadays, nearly all of the tubes are made in Russia and China

Those tubes didn't give better linearity than "consumer" grade ones. Many of the best measuring tubes I've tested over the years were from standard suppliers like JJ or Electroharmonix.

The whole NOS thing is a rationalization of baseball card collector mentality.

 

[peng]

At that level of distortion, anybody might be able to hear it anytime. For once a product that sounds different...

Thanks!

I used to think that but no longer, after reading many articled on the audibility of distortions. Also, based on some online test, not that many people can hear distortions below even 1% (-40 dB) when listening to music instead of test tones. That was through speakers or headphones, when amps in the mix I don't know whether people would score even lower.

Distortion Listening Test

Ran into this interesting listening test by Klippel with regards to how much distortion you can hear. This is the link: http://www.klippel.de/listeningtest/lt/ Just casually wanting to see the test, I went with the defaults and for some reason, the levels were exceptionally low. I had to set...

www.audiosciencereview.com

 

[Bob from Florida]

Why is there more power at 8 ohms than at 4 ohms?

Output transformers match the load - speaker impedance - to the plates of the output tubes for best power transfer. Because the plate impedance is high the turns ratio is chosen to optimize the load. Higher measured power at the 8 ohm tap may be a function of how the output transformer is wound, etc. The different taps - 8 ohm, 4 ohm, etc - are at different turns ratios to accomodate the speaker impedance.

 

[irontortoise]

This is a beautiful-looking lamp and space-heater. I'll give Amir $49.99 to take it off his hands. It will look great in my home office!

 

[Sir Sanders Zingmore]

Output transformers match the load - speaker impedance - to the plates of the output tubes for best power transfer. Because the plate impedance is high the turns ratio is chosen to optimize the load. Higher measured power at the 8 ohm tap may be a function of how the output transformer is wound, etc. The different taps - 8 ohm, 4 ohm, etc - are at different turns ratios to accomodate the speaker impedance.

Thanks
I missed the crucial bit that it was different taps

 

[Bob from Florida]

Those tubes didn't give better linearity than "consumer" grade ones. Many of the best measuring tubes I've tested over the years were from standard suppliers like JJ or Electroharmonix.

The whole NOS thing is a rationalization of baseball card collector mentality.

Do you see any “longevity“ advantages with some NOS OEM’s?

 

[DSJR]

I own a valve-amplifier from EAR. It must be a better designed valve-amp because I don't hear any nice warm fuzzy sound. No richness either. I only hear a folded relatively rumbling bass, less clear treble and generally a bit weak dynamics. And a tendency to mush the sound in intense and strong parts. Not that it sounds bad, but compared to my Purify class D it is kind of tired. But it cuts in a pleasant way. On the other hand my class D does not cut at all.

The 'V6' is quite neutral sounding in the company of its peers, but the other amps in the E.A.R. range I've heard over the years do have a slight 'flavour' to them - slightly darker up top, sweet in the case of some lower powered models and the bass 'feel' is certainly meaty, but in fairness never bloated or 'organic' like a PrimaLuna model (Tim de P certainly knew exactly what he was doing and what was needed for his market). Got to say that had I bought a set of 509's back in 1989 when they were affordable to me instead of the (it appears) stressed out valve eating Tube Technology Genesis mono's, my audio path would have been very different I think.

 

[Pablo27]

But it sounds so warm...

 

[Deleted member 50971]

This is a review and detailed measurements of the Carver Raven 350 tube monoblock amplifier. It is on kind loan from a member and (I think) costs US $4,750.
View attachment 225095

The 350 is not a bad looking amp. It has the same "orange peel" paint job of the previous Carver 275 amplifier I reviewed. At 42 pounds, the unit is pretty heavy. With all the weight in the back, the front handle is kind of useless when it comes to lifting it.
View attachment 225100
There is an XLR input but I believe it is for convenience and performs the same as RCA. I measured the DC resistance of the 4 and 8 ohm terminals (after the measurements) and realized they are both the same! Here I was switching back and forth between them. Anyway, measured DC resistance is 0.47 ohm. The 1-2 ohm tap has a lower DC resistance of about 0.3 ohm.

Unlike the 275 amplifier, the fuses did not blow and the amp survived my sweep tests. Bias is to be set at "80" on the front dial and that was the case when I powered on the unit.

There is a gain control but you are advised to set it to max which is what I did for testing.

There is a flip switch in the front which changes the amount of feedback. I tested the amp in both settings.

Here are the specs:
View attachment 225121

Carver 350 Measurements
Let's start with high-feedback performance using XLR input:
View attachment 225102
There is copious amount of distortion causing SINAD to be dominated by it. At 44.1, it ranks as the second worst amplifier ever tested:
View attachment 225104
It even performed worse than the Carver 275 which had a SINAD of 46. Switching to lower feedback doesn't make things that much worse:
View attachment 225106

Note that gain is reduced and therefore, volume will be different. This makes AB testing tricky. Here is a more detailed FFT showing the small difference between low and high feedback:
View attachment 225115
Notice how distortion is made up of both 2nd and 3rd harmonics so you can't make the argument that it is "2nd harmonic goodness."

As noted, RCA performance is the same as XLR:
View attachment 225107

Power supply 60 Hz noise in both cases causes severe intermodulation higher up in frequency. No amount of grounding impacted that so it is endemic tot he design.

Noise performance is decent for type of amp it is:

View attachment 225108

Intermodulation distortion rears its ugly head again in multitone test:
View attachment 225109

I don't know how anyone could hear more "detail" with such an amp where so much of the music signal will get lost in the distortion "grass."

Frequency response should be flat but it is not:
View attachment 225110
It naturally will have load dependency due to output impedance.

Let's see the power situation as we had serious shortfall in the 275 amp:
View attachment 225111

We don't meet the spec there but come closer with 8 ohm:
View attachment 225112

Back to 4 ohm, here is our 1% THD (double the company spec) max and burst power:
View attachment 225113
We seem to get the same shortfall. There is momentary reservoir though allowing the peak output to shoot way up. This was not always consistent though.

I also tested 2 ohm capability:
View attachment 225114

You are still current limited so no more power.

Changing the test frequency gives us the following power curves:
View attachment 225116

There is some instability at 20 Hz and fairly significant power drop. This points to power supply not having enough capacity as the lower frequency taxes it for longer period. Some drop occurs in every amplifier by the way so it is a matter of how much.

Finally, the amplifier warms up quickly and is pretty stable:
View attachment 225117
Testing occurred after this warm up.

Conclusions
What an upside down the world of audio is. Folks want to pay so much more to get dirtier sound. You want dirty? The Carver 350 gives it to you. Even at 5 watts there is copious amount of harmonic distortion. Power supply mixes with that at such high level that it creates its own spread of distortion. A video must come with these amps that hypnotizes you into thinking you are getting great sound....

I can't recommend the Carver 350 monoblock amplifier.
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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Thank you for the review Amir. Looks pretty messy to say the least, my thoughts are if you go through the trouble of putting XLR input on it it should measure somewhat better because of it.

I know that these distortions should be audible, but has anyone listened to this and/or performed a blind test vs a well measuring amplifier?

Thanks again!

 

[Deleted member 50971]

Hard to say. The tubes themselves make a big difference in sound quality. Companies like GE and Raytheon used to make tubes for industrial applications like oscilloscopes and you wanted maximum quality. Nowadays, nearly all of the tubes are made in Russia and China

I had a McIntosh Mc2102 (sold) and currently have an SFS-80 running Milspec (JAN = Joint Army Navy) tubes. They aren’t state of the art but with those tubes it’s definitely on par with my JBL SA600 to my ears. I’d be shocked if the SA600 did worse than these . @amirm

You can see Stereophile’s measurements of the MC275 here

McIntosh MC275 power amplifier Measurements

Sidebar 3: Measurements

www.stereophile.com

Bascom King measured the SFS-40 here which ran 7 dB of negative feedback. He is the designer of the BHK PS Audio amps as well.

http://www.elektronikjk.com/elektroakustyka/wzmacniacze/wzmacniacze_lampowe/Sonic_Frontiers_SFL-1_Line_Preamp_and_SFS-40_AMP.pdf

Hi. I have NOS JAN tubes that came from a trusted source and test as new, I have bugle boys, I have Telefunken’s, and my conclusion about all of the more is… They all sound the same, and if there’s any difference it’s very small. At least that’s my experience.

One good thing about them I’ll never lose no money on them, and I’m going to have some preamp tubes up for sale soon. But I do understand the cool and fun side of it, as long as I’m not getting any coloration in my music that is.

 

[jtwrace]

When Carver meets an APx555 for the very first time.

 

[roog]

https://distortaudio.org/

Thank you @Killingbeans ill give this a go

 

[Deleted member 50971]

When Carver meets an APx555 for the very first time.

I think Yogi Berra said it best, it’s déjà vu all over again.

 

[xaviescacs]

I have two questions.

Why and A meter and not a V meter as usual?

Why they advertise "less than 0.5 % THD" instead of "up to 0.5 % THD"?

 

[Deleted member 50971]

I have two questions.

Why and A meter and not a V meter as usual?

Why they advertise "less than 0.5 % THD" instead of "up to 0.5 % THD"?

My two cents is, Bob Carver/Sunfire many times have put useless meters on their amplifiers. Looks?!

As far as the THD goes… I think they were hoping Amir‘s equipment broke down. Trust and verify… more of the latter.

 

[Deleted member 50971]

My old Sunfire cinema grand amp had a Joule meter on it, and once turned on it never moved, talk about useless lol.