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Carver Raven 350 Review (Tube Amp)

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 269 82.8%
  • 2. Not terrible (postman panther)

    Votes: 29 8.9%
  • 3. Fine (happy panther)

    Votes: 17 5.2%
  • 4. Great (golfing panther)

    Votes: 10 3.1%

  • Total voters
    325

anmpr1

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Audio Research corporation.
In the late '70s, ARC was seriously thinking of abandoning tubes, in favor of their 'proprietary' Analog Module brick. I'm not even sure what that was... a potted IC or something?

Anyhow, in a press release, Bill claimed they would continue to support legacy devices, selling inventory 'for as long as their was demand'. From the depths of my questionable memory, I think the biggest ARC influencer at that time, Harry Pearson, took a listen to William Z's latest and greatest solid state preamp. Shortly thereafter, the entire Analog Module push was forgotten, and it was back to the future for ARC. LOL

The 'problem' with this stuff from Bob (if Bob even has anything to do with this stuff), is not that it's goofy. His gear always had a little bit of goofy baked in. Customers expected and wanted that. It's that Bob always sold at a reasonable 'blue collar' price. And sold by way of dealers, who then took their cut. So you can guess his margins. Now, he's asking ARC prices for direct sales. I mean, I guess he is actually selling these.

I don't get it. For five large you can buy a 'little' ARC integrated. In six colors (it says here). The damned thing even has 'plug in' modules for a DAC and RIAA stage, for crying out loud.

According to ARC (and they should know) it's functionally simple, visually engaging, and musically sublime, taking listening to a whole new experience. And not only that, it's lovingly hand-crafted in Minnesota. I don't know about anyone else, but Minnesota is a deal sealer for me. Plus, it looks like it's got some digital LEDs indicating something or other. This one is 21. And if you look closely, it's wearing some of those little tube condoms. A very 'safe' amp, no doubt.

Bob really needs to up his game. For five thousand dollars? Unless he's sending Miss Hologram to my house for an extended... um... er... hands on listening session, I'm making Audio Research the stop.

arc.jpg
 

SIY

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So can you show an example (full set of measurements, of course) of a tube preamplifier and power amplifier that would:

1) a preamp having similar distortion parameters as the SOTA solid state designs, i.e. THD about -120dB into 600 ohm load at 4Vrms
2) a power amp with similar distortion parameters as the SOTA solid state designs, i.e. THD about -100dB into 4 ohm load at 100W power and full power BW at both 20Hz and 20kHz

I am curious.
Where did I say this? Especially JUST after I answered the question of limitations in ultimate distortion performance in tube circuits? And since you quoted back my SPECIFIC reason, you clearly read it, though perhaps didn't understand it.

And honestly, who cares? If distortion is down to the 0.00x% region, as is the case for my preamps, it's ridiculously better than needed.

And what kind of moron has 600 ohm loads in a home hifi system? I can design for that, but it's a stupid use of resource and unneeded expense and complication.
 

Asmodeus2112

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So, there are amp measurements, and speaker measurements. Is it possible to do an amp + speaker measurement? Keep the speakers the same, but change the amp from a SS to a Tube and see what the difference is? (Or if this is done somewhere could you point me to some tests, hope this isn't a silly question.)
 

RammisFrammis

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Your high sensitivity speakers can work well with small tube amps, or say with a small 10-25W Class-A amp.
The small Class-A amps are also a bad choice for a modern speaker with a difficult impedance.

Pointing back to the historic speakers and amplifiers, that predated the solid state era, doesn’t really help.
What people did 75 years ago, is not totally germane to what we might do today… but it was what I inferred from you words.

These days if people have low impedance speakers, and want high powered amps, then a high powered tube amp is as good of choice as a high powered SS… at least if $ is not a problem.
But that Carver amp is not an ARC tube amp.

And yes, a small 300b tube amp will not power many modern speakers.
I still say that ANY tube amplifier over maybe 50 watts is irresponsible in today's energy environment. As irresponsible as a muscle car which runs on gas for going to the grocery store. Class D makes far more sense with power hungry speakers with horrible impedance dips and power demands. Building a larger tube amplifier to deal with these types of speakers makes no sense, and such an amplifier cannot even hope to perform as well as the class D amp. Amplifiers like the Audio Research are zombie dinosaurs.
 

GXAlan

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On the topic of tubes, the Vacuum Tube Valley magazine is available online via PDF. In one of their issues, they show the difference in distortion based upon the bias that is being applied. The difference can be under 0.1% versus 0.5%. Looking at the EL34, the difference at a fixed bias between the best and worst tubes is ~0.5% vs 0.7% and the 6550’s is around ~0.5% to 0.7% also.

This sort of gives indirect support for statements that different tubes probably sound VERY similar in blind testing, gives rationale why different tubes may perform differently (since the EL34 and 6550 will handle bias differently), but also why tube amplifier tests should specify which tube, and what bias (once warmed up).

08AA5EC2-F2D7-4BF5-843C-14B1C285B017.jpegD3F7AD01-E4B1-47DD-A05E-AFF00A689B9E.jpegEE7D1FEE-32A7-47B7-8FA7-7F73DF16F990.jpeg

So, there are amp measurements, and speaker measurements. Is it possible to do an amp + speaker measurement? Keep the speakers the same, but change the amp from a SS to a Tube and see what the difference is? (Or if this is done somewhere could you point me to some tests, hope this isn't a silly question.)

Not speakers, but here are headphone measurements (which presumably is easier to avoid run-to-run variation)
https://www.reddit.com/r/headphones/comments/9evcjd/_/e5s97hz
Not my test, but just one I bookmarked. Frequency response is identical for many of the headphones, bass is higher for some. Distortion is different.
 

Ken Tajalli

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They can indeed have much more negative feedback applied and generally do. But the circuits start out far more non-linear, so the distortion reduction starts out with a different basis.

OTLs can definitely have a bandwidth advantage.
My OTLs (now in storage) have two distinct sections. A class A balanced input/voltage gain section (one double triode), and then the driver and output section.
There is no global feedback!
The driver/output section has a large feedback. the input section has local feedback.
Output imp. is just under 1 ohm, with two 6C33C tubes, I get about 25W, with four about 60W.
I used to mostly run it with two, that was enough for me (around 10W).
 

Blumlein 88

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So, there are amp measurements, and speaker measurements. Is it possible to do an amp + speaker measurement? Keep the speakers the same, but change the amp from a SS to a Tube and see what the difference is? (Or if this is done somewhere could you point me to some tests, hope this isn't a silly question.)
It could be done, I don't happen to know of it being done. Generally most tube amps will measurably alter the frequency response due to output impedance interacting with the speaker impedance. It would be more revealing to measure at the speaker terminals between two different amps. The bottom line is tube amps probably do have a sound in most cases. It isn't a higher fidelity, but you might prefer it.
 

pma

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So, there are amp measurements, and speaker measurements. Is it possible to do an amp + speaker measurement? Keep the speakers the same, but change the amp from a SS to a Tube and see what the difference is? (Or if this is done somewhere could you point me to some tests, hope this isn't a silly question.)

No problem to do it, I have plenty of such measurements, for myself. But do not expect that the reviewers will do it, it may be time consuming and there will be an excuse that the result would not be universal. In a fixed setup you get some comparison. But for the normally designed solid state amplifiers with flat frequency response and low output impedance you get the same measurements at the acoustic output of the speaker. You get some differences in the near field, like few cm from the speaker cone, as a result of different signal to noise ratio of various amplifiers.
 
OP
amirm

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So, there are amp measurements, and speaker measurements. Is it possible to do an amp + speaker measurement? Keep the speakers the same, but change the amp from a SS to a Tube and see what the difference is? (Or if this is done somewhere could you point me to some tests, hope this isn't a silly question.)
I have not done it with speaker system. But have done with Stax headphone. The amp distortion definitely travelled through the headphone.
 

mhardy6647

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The 'problem' with this stuff from Bob (if Bob even has anything to do with this stuff), is not that it's goofy. His gear always had a little bit of goofy baked in. Customers expected and wanted that. It's that Bob always sold at a reasonable 'blue collar' price. And sold by way of dealers, who then took their cut. So you can guess his margins. Now, he's asking ARC prices for direct sales. I mean, I guess he is actually selling these.
Carver devotees are pretty... umm... devoted.
To the point of what I like to call nonlinearity. I.e., they'll slurp products like this up -- and especially if Dr. Carver signs 'em with a silver (or gold) Sharpie*!
;)

Unless he's sending Miss Hologram to my house for an extended... um... er... hands on listening session, I'm making Audio Research the stop.

I'm sure you meant ears-on -- right?
:cool:


index.php

The little matrix display "1" and "2" really make that AR amp pop.** I guess ARC's got the lock on the IP. Eat your heart out, McIntosh! :D

_______________
* Not to be confused with a Sharpei. :cool:
**
In most of my amplifiers, it's usually a capacitor that makes 'em pop.
:rolleyes:
 
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amirm

amirm

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dougi

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Are you sure that isn't an oven? With those handles, and the metal front with glass window, it looks like something for a trophy kitchen.
A kitchen would be cheaper.
 

dougi

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I think part of the problem is that tube stages don’t have a lot of gain to start with, so the amount of negative feedback (the #1 distortion killer) that can be applied in an amplifier is limited.
Speaking of gain vs feedback, how is it that this Carver seems to have more gain on the high feedback setting compared with the lower feedback one? Isn't that counter to the normal expectation? I assume some peculiarity of how the feedback switching is done.
 

theREALdotnet

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Are you sure that isn't an oven? With those handles, and the metal front with glass window, it looks like something for a trophy kitchen.

Nah, that’s how high-end AV gear is supposed to look. Consider this laser disc player for example:

1661205502994.jpeg
 

Asmodeus2112

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I have not done it with speaker system. But have done with Stax headphone. The amp distortion definitely travelled through the headphone.
Thanks Amir, I'm curious how the "Tube Sound" would show up in speaker tests like the ones you perform. As you show distortion would transfer, and I assume frequency response would be different, could anything else be measured? Maybe a fools errand, but can things like damping effect be measured at the speaker?
 

DonH56

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Damping factor is related to output impedance so low DF will cause greater variation in frequency response into a speaker or other non-flat load. Actually measuring the DF at the speaker, meh, that's essentially measuring the amplifier's output impedance after the speaker cables. The good news is for most tube amps the cables contribute negligibly since the output impedance is so high.
 

Asmodeus2112

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Damping factor is related to output impedance so low DF will cause greater variation in frequency response into a speaker or other non-flat load. Actually measuring the DF at the speaker, meh, that's essentially measuring the amplifier's output impedance after the speaker cables. The good news is for most tube amps the cables contribute negligibly since the output impedance is so high.
Ok, thanks. I do not have the detailed knowledge about all of the details involved here, just wondering overall how much of the amplifier differences could be measured in the air after the speaker.
 
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