Carver Crimson 275 Measurements

[MakeMineVinyl]

TT motor could work if designed for that.

Yes, that's how the phonograph was originally set up. As far as I know, this arrangement was the norm with cheapie phonographs of the day, with a single 50L6 tube, crystal cartridge and in the case of this phono, a 3.2 ohm speaker. The measurements I did were with a 4 ohm load. The amp will put out about 500 milliwatts before clipping at 1kHz.

 

[egellings]

I remember the 117L7 tube, which had a 50L6 and a 35Z5 rectifier in the same GT size bulb.

 

[MakeMineVinyl]

I remember the 117L7 tube, which had a 50L6 and a 35Z5 rectifier in the same GT size bulb.

Now you've got me curious about the schematic I have for that phono amp - I'll have to try to dig it out.

 

[mhardy6647]

Yes, that's how the phonograph was originally set up. As far as I know, this arrangement was the norm with cheapie phonographs of the day, with a single 50L6 tube, crystal cartridge and in the case of this phono, a 3.2 ohm speaker. The measurements I did were with a 4 ohm load. The amp will put out about 500 milliwatts before clipping at 1kHz.

we're drifting a little off-topic here but here's my personal favorite way to die at the hands of a phonograph with a series-string amplifier. This one's stereo, though, and avoids the dumping of 60 to 70 AC volts to warm the room or set the house on fire.
Don't stand on a damp concrete slab when spinnin' your Beatles record, though, or you could wind up smoking more and enjoying it less (as my best/favorite high school science teacher was fond of saying).

Obviously, the addition of a 1:1 isolation transformer on the "supply side" would render this design much less terrifying to 21st Century eyes.

 

[mhardy6647]

One final (I hope!) digression from me: Y'all do know that in DIY vacuum tube parlance, amplfiers such as discussed in the previous few threads are fondly referred to as spud amps... i.e., one tubers.

OK, Imma stop now. Honest.
Back to the Carver-fun!!!

 

[MakeMineVinyl]

we're drifting a little off-topic here but here's my personal favorite way to die at the hands of a phonograph with a series-string amplifier. This one's stereo, though, and avoids the dumping of 60 to 70 AC volts to warm the room or set the house on fire.
Don't stand on a damp concrete slab when spinnin' your Beatles record, though, or you could wind up smoking more and enjoying it less (as my best/favorite high school science teacher was fond of saying).

View attachment 178542

Obviously, the addition of a 1:1 isolation transformer on the "supply side" would render this design much less terrifying to 21st Century eyes.

This reminds me of the AC/DC radios we built in my high school electronics class. The teacher admonished us to check the AC voltage potential between your chassis and the guy next to you, lest you bump up to each other and go up in smoke.

 

[TriodeLuvr]

I would agree completely that, most of the time, comparing a tube amp with a Crown or Eigentakt is ludicrous, were it not for the unhappy reality that there are people out there at this very moment claiming that tubes still “sound better” than solid state.

My professional experience includes warranty service for Crown, Revox, B&O, Dynaco, Phase Linear, Sansui, Teac, Akai, and many other well-regarded brands. That was in the '70s and '80s. My listening experiences then and since expand that at least three-fold, adding names like Levinson, GAS, NAD, SAE, etc. You can believe that I not only know what solid-state sounds like, but that my permanent switch to vacuum tube amplification some 25 years later was not an arbitrary decision.

As a measurement person, I certainly agree that numerical comparisons between these two genres are worthless. But I also believe the audio industry has produced an overwhelming amount of solid-state equipment for all the wrong reasons. Solid-state gear is cheaper to produce and easier to market to a consumer populace eager to believe it will bring the best of modern sonic technology into their living room. Much of it fails miserably in that regard, but it continues to find favor for reasons of cost, size, power consumption, and above all, profitability. Those of us who believe in the audible superiority of vacuum tube gear are not fooled.

I know this is a contentious subject, and I don't wish to debate it with the masses. Nevertheless, I stand by what I've said here, and I hope each of you who has not enjoyed the privilege of hearing a musical performance reproduced at its finest will someday find the time to audition a well-designed system utilizing only tubes. I do this every day, and like I said earlier, I'll never go back.

Jack

 

[egellings]

I think the draw of S.S. was its reliability, low heat output, and compact lightweight size; no tubes to fizzle out & need regular replacement and no bad backs caused by heavy transformer-laden chasses. My preference happens to go with home brew tube amps & preamps. They're fun to make, parts are readily accessible, and when you're done, there's the music. I'm a happy camper, and if the equipment breaks down, I can readily get it going again. As for the weight, well, I am a gym user, so it's no big deal.

 

[paulbottlehead]

we're drifting a little off-topic here but here's my personal favorite way to die at the hands of a phonograph with a series-string amplifier. This one's stereo, though, and avoids the dumping of 60 to 70 AC volts to warm the room or set the house on fire.
Don't stand on a damp concrete slab when spinnin' your Beatles record, though, or you could wind up smoking more and enjoying it less (as my best/favorite high school science teacher was fond of saying).

View attachment 178542

This is a really good example of an amp that should not be run without a load!

 

[LTig]

As a measurement person, I certainly agree that numerical comparisons between these two genres are worthless. But I also believe the audio industry has produced an overwhelming amount of solid-state equipment for all the wrong reasons. Solid-state gear is cheaper to produce and easier to market to a consumer populace eager to believe it will bring the best of modern sonic technology into their living room. Much of it fails miserably in that regard, but it continues to find favor for reasons of cost, size, power consumption, and above all, profitability. Those of us who believe in the audible superiority of vacuum tube gear are not fooled.

My eperience was just the opposite. When I looked for a better amplifier in 1988, to replace my Kenwood KA80 which needed repair too often, I stumbled upon a 25Wpc tube amp from Audio Innovations. In the shop it sounded much better (smooth, soft, relaxed - you name it) than a similar expensive but much more powerful solid state pre/power amp combo (Parasound?).

A few weeks later in another shop I had the chance to audition the Audio Innovation amp and another solid state pre/power amp combo (Audioplan Homogen/Amber ST70, about 40% more expensive). This combo was even smoother than the tube amp and its bass control was better, so I bought it. At this point I knew that both technologies have potential for excellent sound and then the choice for solid state is a no brainer (less heat, less maintenance, more power, usually cheaper).

 

[Xulonn]

Those of us who believe in the audible superiority of vacuum tube gear are not fooled.

Indeed! Strong beliefs often overwhelm reality!

 

[restorer-john]

The measurements I did were with a 4 ohm load. The amp will put out about 500 milliwatts before clipping at 1kHz.

A real powerhouse.

The very first amplifier (SS) I built put out 500mW per channel running off my model train transformer. I think I was about 11 or 12yo. You can imagine the next thing I built was a regulated 2A 12V power supply to run it... Oh, and some flag heatsinks for those poor BD-139/140s. Those Philips transistors took a beating running multiple paralleled speakers I'd pulled out of car doors at the scrapyard.

 

[dfuller]

yeppers.

to wit (and FWIW)...

View attachment 178534
source: https://worldradiohistory.com/Archive-Catalogs/Allied-Catalogs/Allied-Catalog-1960.pdf

Nowadays, we might say "landscape or portrait."

That is a fascinating speaker having an 8 inch, um... tweeter?

 

[mhardy6647]

That is a fascinating speaker having an 8 inch, um... tweeter?

Do you know about Edgar Villchur's (Acoustic Research's) first loudspeaker, the AR-1 of the mid to late 1950s?

The AR-1 was the first commercial "acoustic suspension" loudspeaker. The AR-1's "tweeter" was the famous Western Electric (later Altec) 755(A) -- which, today, is worth far, far more than the AR-1 in which one might, if one were lucky, find one. The 755 is an 8-inch 'fullrange' (extended range) driver, which was used as the (for lack of a better word) tweeter to extend treble response of the AR-1.

The EV Leyton originally used an EV "Wolverine" LS-8 twincone "fullrange" driver as its "tweeter". The LS-8 is a nice little driver -- not in the same league as the 755A... but a nice little driver. I have... umm... a few LS-8s "in stock" here.


Here's one of the LS-8s installed in a really cheezy 'test baffle' at one point a few years back

Here's another LS-8 in situ as the midrange driver of the next model up from the Leyton -- the EV Esquire. The Esquire added an EV T-35B as a proper tweeter The Esquire is a darned fine sounding little loudspeaker... similar in performance to Klipsch's Heresy but without the screechy MR horn, a better-behaved tweeter*, and more bass.


... youse guyses pulled me off-topic... again!

________________
* For whatever reason, the T35B with EV's simple XO is far less ear-gouging (to me) than was the EV T35 in a Heresy with Col. Klipsch's XO. EV generally got better sound out of the T35 family members (e.g., EV coaxes that used them, as well as speaker systems) than other manufacturers who used them in their own designs.

 

[MakeMineVinyl]

Hey, let's talk about pressure washers.

 

[BlackTalon]

Hey, let's talk about pressure washers.

passee. Ultrasonic cleaners are where it's at

 

[jjptkd]

This is a really good example of an amp that should not be run without a load!

Have you seen the replies to this thread on the Jim Clark forum? They claim there's a special way to test them?

Carverfest Amps and how to measure them. A note from Bob. – Carver Stereo Forum

QUESTION: Bob, A guy is claiming a 275 makes 17 watts with strange distortion numbers any thoughts?



ANSWER: Thats ridiculous, a 75 watt amp.. Isn’t it obvious? It is being test wrong or its damaged.. My amps can be difficult to test, difficult to get the grounding correct. I’ve been dealing with people testing my designs wrong and getting grounding errors effecting measurements, most of my life.

 

[paulbottlehead]

I did try hooking just my scope up to the speaker terminals and no analyzer with my scope running on its internal battery (so completely floating), and this did not change the waveform appreciably. I will submit to ASR this image, as I borrowed a bathroom mirror out of my house so you can see that the amp is drawing lots of current. You can see my generator hooked up to the amp (not even using my FFT for this).

Notice there's no power cable going to my scope as it's running on its internal battery. Also notice that I have my scope leads hooked up backwards so if there was an earth reference at the scope, it would short the output and I'd see nothing. Swapping the scope leads doesn't change the waveform under these conditions.

Here's a scope grab. I don't do a lot with push-pull and I'm not sampling to measure THD, but that's a LOT more than 1% THD.

Tomorrow I will drop off the production unit to Amir.

 

[Tom C]

The day we’ve all been waiting so impatiently for!

 

[Blumlein 88]

You probably should put at least 470 ohm load across the outputs of a xfmr coupled tube amp like that. Normally you don't want to run one with no load connected.