The old school shortcomings of vacuum tube amplifiers solved by Bob Carver's RAM 285.

[Ar9Jim 6,057]

 

Vacuum tube technology turns 120 yrs old in 2024.

 

Common shortcomings of the past:

 

1) Issue: Tubes run scalding hot and present a burn risk to pets or children.  Solution: Bob Carver designs run tubes relatively cool, only being quite warm but not scalding hot.

 

2) Issue: Tubes need to be replaced every 1-3 years at high replacement cost to the owner.  Solution: The cool running Bob Carver design has a history of over 10 years. On the rare occasion that service is required, tubes as old as 10 years still test within new specifications. Bob calculates they should last past 40 yrs.

 

3) Issue: Tube amplifiers roll off at low frequencies in general, giving them the old school reputation for great mids and highs, but less performance at bass frequencies compared to solid state. Solution: This is correct in most cases, although tube amps have an ability to increase voltage in response to increases in loudspeaker impedance, often found at bass frequencies. This ability contributes to making tube amps sound more powerful than their power rating would suggest in comparison to solid state, although below 50 Hz or so, tube amps tend to roll-off.. Notice tube amp specs from (all?) tube amp companies compared to solid state specs.

 

I'll use 75 watts in this example like the error with the Crimson 275 quantifiers that caused issues before my time here. This is where the difference in quantifying matters. Typical boiler plate solid state spec.. (75 watts 20Hz to 20Khz, 8 ohms, .001 THD+N).. Compared to typical tube amp spec.. (75watts 1Kz, .5% THD+N).. It's a huge difference that salesmen can make a mess of.. If salesmen use the solid state quantifiers on a tube amp, a measuring site with make a big deal out of it. The Black Magic 275 meets the tube amp specs used today, while being essentially the same as the Crimson 275 with some updates. Tube amp companies spec power and THD at 1Khz for this reason. Into a standard resistive load at low frequencies, the power generally rolls off in this type of 8 ohm drain test.  

 

The RAM 285 is different. The RAM 285 spec is at full rated power 20 Hz to 20Khz. It's a beast of a tube amp. It will make full rated power exceeding the audio bandwidth from below 18Hz to beyond 20Khz w/n only +- 1 db. (not 3db). The spec is not written in error by sales like the earlier 275, this is all engineering. Actually the 285 will meet it's specs past 100 WPC so we have a comfortable margin built in. The RAM 285 has textured resolution in the low end, as deep as your speakers will go.

 

4) Issue: Tube amps need efficient speakers and limit your choices. Solution: The RAM 285 is a simultaneously high voltage, high current, heavy weight design. We factory listening test the RAM285s using Magnepan speakers in order to provide enough load to make the RAM285 exercise.

 

5) Issue: Tube amps with efficient speakers tend to have more background noise:  Solution: Technology. The RAM 285 uses the latest manufacturing engineering technology to solve higher noise often associated with vintage designs. Computer aided design, prototyping and simulation technology, common in aerospace, have enabled the very best performance possible from the genius circuit design of Bob Carver. The RAM 285 SNR exceeds 100. Customers report lower background noise than their solid state amplifiers.

 

That's the RAM 285. Best of tube amplifiers without the shortcomings. A true legacy level product from Bob Carver, a brilliant physicist who has spent a lifetime improving our enjoyment at a price more could afford.

Edited December 11, 2023 by Ar9Jim

[4krow 5,077]

I do appreciate this explanation. Specs and numbers get regularly fouled up by sales staff among others as well. You know, if you say something with enough conviction it assures the listener that your opinion has merit. Again, there is nothing like an in home test for this. Dam all the specs. What does it sound like in your environment? Even then, you better give your opinion some time to settle in.

[radtraveller 216]

Well, will be able to see / hear next weekend, I hope.

At least initially, will set direct to maggie 1.7i.

 

should have both the RAM285 and a thoroughly rebuilt 4000t from Nelion arriving this week.

Might be another couple of weeks until I can get the whole system set up.

Still need to obtain some marble or heavy quartz for setting the amps on.

Christmas downtime project probably..

 

Anyone have any good ideas, other than setting the amps up in adjacent room, to protect tubes from..high intensity sound waves?

I can run longer, heavier gauge speaker wire rather than having the tubes shaken like a james bond cocktail..

 

[4krow 5,077]

I was able to buy machinists' 2" thick marble slabs for much less than I thought they would be. I think that they were 11" X 14" which was just right for the small mono blocks that I was using. Not that it matters but they were machined to one ten thousandth of an inch. 

 I have to ask, if you are concerned with vibration migrating into the tubes, just how loud are you going to be playing music? And what are you using for bass? If it is a sub, then perhaps there is reason for this thinking, but in normal terms, I don't think that you will be able to hear any effect of the airborne or otherwise vibration that the tubes have to endure. I would say otherwise with a tube that is high in microphonics such as the miniature 3S4. 

[radtraveller 216]

Tekton Double Impact SE

Tekton 2x10 subs (2 of them)

magnepan 1.7i

When everything is hooked up.

 

490t

Gustard r26 ladder dac
4000t external processor loop to eq.
4000t output A to sublime audio xover to tekton amps.  Two sub outs..

4000t output B to Maggies.

RAM285 (tekton biamp mid-high)

Silver 7t (tekton woofers)

Silver 7 900, Magnepan, 100hz high pass to amps.

300 watts on each powered 2x10 sub

 

LOUD..  🙂. When I want to.. with either tektons, maggies or both pairs. Many options for dialing in how I want to hear on any given day..

 

not just hearing microphonics, a little concerned damaging hot tubes with vibrations..  the marble or quarts will sit on top of cork cushions themselves on top of a thick wood shelf, on top of a sturdy cabinet base.. and the devices themselves have their own feet..  I want to have an 8-9 foot long area.. 7-900 power on outside, then 7-900 tubes, then 7ts, then 285 in center.  4000t, 490t and dac sit on shelf underneath.  Unless I stick the amp in back room, then 4000t, dac and cd will be on an audio platform in main room and wites running back to amps, then speaker runs.. none more than 12 feet..

 

just to be clear, this is purpose built for 2 channel audio.  The home theater system is an entirely different (and waaaaay less expensive) setup.. I just don’t watch movies or tv that much. So the surround probably not much of an issue.. though I might try it for concert hall effect sometime in the future.

 

Edited December 10, 2023 by radtraveller

[radtraveller 216]

If I ever have the cash in the future, I may upgrade the Double Impacts.. but now I am done spending money on equipment for awhile..  I still have a bunch of Carver gear, almost all  refurbed by Hitech or Nelion then tested and enjoyed for limited periods when I had time then boxed up and stored in a controlled environment. I don’t even remember all of the pieces now, but I do still have 3 pieces I need to get refurbed at some point.. CT-19, 390t and a 760x.

Just from memory:

1.5t x 4

1.0t x 2

tfm-42

tfm-55 X2

i think I have a couple more amps also.. just cannot remember the models.

out on loan to nephew is a hr-875 and a non-tube 5 disc carousel cd (cannot remember model#)

And my original two Pieces, the Carver Receiver (130w) and a dtl-200 circa 1987.

plus what I have and will shortly have here in Reno, the 490t, Silver 7-900, the 7ts, RAM285 and 4000t.

nope, don’t get involved in repairing Carver, but many years of experience with SS stuff. Looking forward to experiencing all that tube glory 😉

 

next time I visit Oregon, maybe I will lay everything out and post some pictures.

[Ar9Jim 6,057]

1 hour ago, 4krow said:

I was able to buy machinists' 2" thick marble slabs for much less than I thought they would be. I think that they were 11" X 14" which was just right for the small mono blocks that I was using. Not that it matters but they were machined to one ten thousandth of an inch. 

 I have to ask, if you are concerned with vibration migrating into the tubes, just how loud are you going to be playing music? And what are you using for bass? If it is a sub, then perhaps there is reason for this thinking, but in normal terms, I don't think that you will be able to hear any effect of the airborne or otherwise vibration that the tubes have to endure. I would say otherwise with a tube that is high in microphonics such as the miniature 3S4. 

Found similar marble and granite in 1 inch thick at a countertop shops. They have pieces left over from sink cut-outs etc. and will cut to your size. The mass seems to isolate well. Could get fancy with 1 inch thick layers of marble with rubber sheet between the layers. 

[radtraveller 216]

Is rubber better than cork?  I went with cork based on some article I read, but can’t find it now.. smh.. getting old..

[4krow 5,077]

Maybe it is better to know what frequencies that rubber vs cork attenuate/control. What comes to mind for me is a rolled-on coating that can be built up by coats on two different opposing surfaces giving you constrained layering (the same idea as cork or rubber). I would venture a guess that the two slabs being used for this be of two different thicknesses.

 This is a subject that has always been of interest to me.

[Ar9Jim 6,057]

9 hours ago, 4krow said:

Maybe it is better to know what frequencies that rubber vs cork attenuate/control. What comes to mind for me is a rolled-on coating that can be built up by coats on two different opposing surfaces giving you constrained layering (the same idea as cork or rubber). I would venture a guess that the two slabs being used for this be of two different thicknesses.

 This is a subject that has always been of interest to me.

Likely an accelerometer available for measuring the results. Could be fun. Common sensors for vibration testing in aerospace. Used on machines known as "shaker tables" that induce vibrations at test frequencies while measuring electronics performance.https://clarktesting.com/service/vibration-testing/?gclid=EAIaIQobChMI_Orv0bGHgwMV5CvUAR3MEgtqEAEYASABEgJNVPD_BwE

Edited December 11, 2023 by Ar9Jim

[radtraveller 216]

Ok, so I submitted a question on their website asking if they had any relevant prior testing they could reveal or advise for isolating tube amps in the presence of high spl audio.

 

Will report any reply.

 

by the way, RAM285 just showed up..  got to eat dinner first though.

[radtraveller 216]

On 12/10/2023 at 4:37 PM, Ar9Jim said:

Found similar marble and granite in 1 inch thick at a countertop shops. They have pieces left over from sink cut-outs etc. and will cut to your size. The mass seems to isolate well. Could get fancy with 1 inch thick layers of marble with rubber sheet between the layers. 

Stopping by counter top place tomorrow to see about any fall offs.

[radtraveller 216]

Short.. gotta find a better way to convert qucktime video to mp4..

[radtraveller 216]

A little better….

Sounds good.  Gets a little distortion at really high volume. 
Found I cannot use the maggies yet.. I cannot find the fuses I ordered so.. ordered some more.. Maybe this weekend..

[Ar9Jim 6,057]

Looks like 85 watts is serving you well power wise. How do you like the sound quality at less than hearing damage levels?😁

Edited December 12, 2023 by Ar9Jim

[radtraveller 216]

Later last night, I relaxed with some HD AC/DC before bed. (About 80db at my seat)

Very enjoyable.  This is full range to the tektons with the 2 subs getting signal from the 285 sub outs.

i imagine it would be better if I high passed the amp, used the sub outs at the eq and adjusted the subs to 110 or so.(for high spl), easy switch..I’ll try that this evening.

That was straight from DAC. Did not adjust any settings on it from SS use, so some play time there in my future.

4000t is supposed to be here tomorrow..

Edited December 12, 2023 by radtraveller

[radtraveller 216]

Just a thought…

I have 8ohm and 4 ohm speakers.

An A/B switch would be cool.   A=8ohm outs and B=4ohm outs. Autoselect the feedback with switch position.

[AndrewJohn 8,184]

14 hours ago, radtraveller said:

Stopping by counter top place tomorrow to see about any fall offs.

Those counter-top shops around here are putting a premium price on cut-outs..., lots of creative uses are making them see profit opportunity, as opposed to getting rid of them so they don't build up as waste in the yard.  I probably don't live in the best place for "good deals."

[Ar9Jim 6,057]

6 minutes ago, AndrewJohn said:

Those counter-top shops around here are putting a premium price on cut-outs..., lots of creative uses are making them see profit opportunity, as opposed to getting rid of them so they don't build up as waste in the yard.  I probably don't live in the best place for "good deals."

The countertop shops water jet cutting granite and marble sure lends itself to a DIY open baffle speaker design, right? Value added process.

[AndrewJohn 8,184]

OK, I was thinking..., Zoro, and even Amazon, sell some B-grade Granite Surface Plates that may be more economical than engaging with the local counter-top maker..., 

 

...and you can save gas, because these are "prime", and free delivery for something that weighs 80+ lbs.

 

Below is the size that would fit under a Silver 7t Monoblock.  For 2 x $86, for a block of granite that is 2 inches thick.

 

 

[radtraveller 216]

Fall off not to my liking.

https://www.homedepot.com/p/NewAge-Products-3-ft-Solid-Surface-Countertop-in-Black-Galaxy-Granite-89106/315511240#overlay

need 3 of em, but they are 76 pounds each..  Thats pushing it for me to move around.  Could always put on a second layer too.. with another layer of cork or rubber between.. but that might be just a little overkill.

And I like the black. 🙂

But it is a total of >2x what I thought I would pay.. sigh.. 15 years ago, when I bought pieces to do an above garage apartment, stuff was alot less expensive..

But at 225+ pounds, that top should be a sufficient base for the RAM285 and the Silver Sevens 

Edited December 13, 2023 by radtraveller

[3M_Audio 880]

just a thought about a base...make up a 2" high frame of exactly the shape/size you want and mix up some cement, pour, and then polish?

 

 

[xavionics 1,406]

I have a 16” x 16” concrete paver I have used under a turntable when all I had was a wire rack system at the time.

 

https://www.lowes.com/pd/Square-Gray-Concrete-Patio-Stone-Common-16-in-x-16-in-Actual-16-in-x-16-in/3034746

 

Cheap, readily available and effective.

 

Just wrap it with some wood of your choice…😎