How many Tube watts do I need?

eclein · « **on:** 19 Dec 2010, 04:46 pm »

I am seriously considering getting a tube integrated or tube amp and I don't really know how much power I need.
My room is like 12 X 16 roughly and my current speakers- JBL 4312A's are rated 91db sensitivity and I listen nearfield at comfortable levels, when other audiofools drop by they usually want to turn up the volume.
I currently use a Virtue TWO.2 amp and love it, it has plenty of power with the 30/130 power supply, about 55 watts a side my Grant Fidelity Tube DAC-09 is used as a pre & DAC and adds a bit of tube flavor to the sound. I'm perfectly fine with my current setup, love it actually, but I'm curious about hearing an all tube sound. Do I need 10 watts? 30 watts? more? less? You guys know tube watts and I don't so any guidance is much appreciated. Thanks..Ed

Ericus Rex · « **Reply #1 on:** 19 Dec 2010, 08:33 pm »

My room's a little larger than yours (with 10 ft ceiling), my speakers are 91.5 db sens and I get ear-piercing volume out of my 40 watt/channel tube amp. You'd do fine I would guess with 20 or more watts; maybe even 10 since you listen near-field at comfortable volumes.

wywires · « **Reply #2 on:** 19 Dec 2010, 08:49 pm »

Since you are a drummer and like to hear drum kit and percussive slam with realism, I would suggest no less than 40 watts. In addition to speaker sensitivity, you also need efficiency data to determine power requirements. 91.5dB, one watt, one meter is fine but what is the minimum impedance and at what frequency? If minimum impedance is well within the audible band and drops well below 4 ohms, then you need more power. As an example, Martin Logan speakers have respectable sensitivity but minimum impedance drops to below one ohm on some models. Wilson's have the same problem, especially the Watt/Puppy's.

FullRangeMan · « **Reply #3 on:** 19 Dec 2010, 08:55 pm »

Hi,
Other topic in this forum mention the dealer PacificValve this week, so perusing his site I find this 805 SET amp from chinese MingDa manufacturer, seems inexpensive by USA standards, 2,700dollars/pair and 40 tube Watts per monoblock.
http://www.pacificvalve.us/MD3008A.html
Iam salivating over this amp, cause it is a integrated monoblock, a very rare bird, and the 805 tube sell for 90dollars/each in this shop. An YouTube video inform this MingDa 805 amp can drive hard to drive speaker as Magnepan and others.

This is the only Tube or SolidState amp that fits my needs, since 1999 when I began pay attention on tubes, even the Polish site Lampizator rave about this amp:
http://www.lampizator.eu/AMPLIFIERS/CHINA/Mingdamc300-C/ming-da.html
Scroll down the page.
Good Luck, Gustavo

>Never go to a psychiatrist, adopt a cat or dog from the street. On the streets pets live only two years average.

eclein · « **Reply #4 on:** 19 Dec 2010, 09:25 pm »

Here are better specs:
Nominal Impedance -8 ohm
Power Rating -100 watts
Freq. Response- 45Hz to 20 kHz(+-3db)
Sens,-91db, 1W, 1M
Crossover Freq.- 1.5kHz, 7 kHz

The specs being what they are I think right around 40Watts outta get me there, I just wanted to make sure if I try it I get enough, the first amp I was lusting after was like 8 Watts, an expensive 8 watts and sounds like not enough...Thanks Alex, Fullrangeman & Ericus Rex

wywires · « **Reply #5 on:** 19 Dec 2010, 09:42 pm »

Just sent you an email...

TONEPUB · « **Reply #6 on:** 19 Dec 2010, 10:07 pm »

There is no difference between "Tube Watts" and solid state or class D watts. They are all the same. How they distort, how they compress and how much headroom either amp is designed with will make a difference.

eclein · « **Reply #7 on:** 19 Dec 2010, 10:19 pm »

TONEPUB...thanks, I know a watt is a watt but I always read reference to "good tube watts" etc..which led me to believe that the actual number was being fudged or weaker some how. I have a tour hybrid integrated tube amp that is supposed to be 20 watts and although it can drive my speakers and I don't doubt its 20 watts it just sounds thin and kind of anemic so I didn't want to make a mistake a buy underpowered.

FullRangeMan · « **Reply #8 on:** 19 Dec 2010, 10:20 pm »

Quote from: TONEPUB on 19 Dec 2010, 10:07 pm

There is no difference between "Tube Watts" and solid state or class D watts. They are all the same. How they distort, how they compress and how much headroom either amp is designed with will make a difference.

Sorry this ''tube Watts'', I mean say tube Watts in real life driving a speaker, not in a tone test senoid scope.
As is said by many tube custumers, one tube watt have the efficiency of two or more transistor watts, when driving a speaker with music.
Regards, Gustavo

>Never go to a psychiatrist, adopt a cat or dog from the street. On the streets pets live only two years average.

srb · « **Reply #9 on:** 19 Dec 2010, 10:40 pm »

The JBL 4312A is rated at 8 ohms nominal, but it's impedance doesn't dip too much lower in the lower frequencies. The impedance graph shows it reaches its minimum of 3 ohms between 5KHz and 10KHz.

The Virtue TWO.2 is rated at ~ 44W/ch @ 8 ohms and 87W/ch @ 4 ohms with the 130W supply. I would also venture to say you would probably be happier with a tube amplifier with 30W - 40W per channel.

Steve

Wind Chaser · « **Reply #10 on:** 19 Dec 2010, 11:07 pm »

Don't buy a tube amp merely for the sake of buying a tube amp in the hope of coming away with something better. It's not that simple. Your Virtue amp will put a lot of tube amps to shame. The same reasoning in choosing a SS amp must be applied in choosing a tube amp.

As previously stated, watts are watts. Makes no difference what amplifier they come from.

eclein · « **Reply #11 on:** 19 Dec 2010, 11:11 pm »

Steve you always have great stuff....I never knew how to read the graphs or what they meant but your post flipped the switch in my brain, I'm dim...but I see whats happening now, speakers present more of a load to an amp (lower ohms) when trying to recreate lower frequencies..correct? So when a speakers nominal impedance is 8 ohms thats like an average as the "ohmage" fluctuates depending on how much work it takes a particular speaker to recreate certain freqs. Am I right in thinking that a passage in a song that has alot of low end drives the ohm load say from 8 down to 4 because its harder to reproduce those freqs??
If so, then I am officially smarter now then 10 minutes ago...

or not...

srb · « **Reply #12 on:** 19 Dec 2010, 11:28 pm »

Quote from: eclein on 19 Dec 2010, 11:11 pm

Am I right in thinking that a passage in a song that has alot of low end drives the ohm load say from 8 down to 4 because its harder to reproduce those freqs??
If so, then I am officially smarter now then 10 minutes ago... or not...

Maybe not! Certainly some speakers have lower impedances with lower frequencies, but this particular speaker has a fairly even impedance around ~ 6-8 (?) ohms througout the low frequency range, except for a higher impedance peak of > 30 ohms between 50Hz and 100Hz.

This speaker then reaches it's lowest impedance of ~ 3 ohms just before 10KHz.

Steve

TONEPUB · « **Reply #13 on:** 19 Dec 2010, 11:48 pm »

Quote from: FULLRANGEMAN on 19 Dec 2010, 10:20 pm

Sorry this ''tube Watts'', I mean say tube Watts in real life driving a speaker, not in a tone test senoid scope.
As is said by many tube custumers, one tube watt have the efficiency of two or more transistor watts, when driving a speaker with music.
Regards, Gustavo

>Never go to a psychiatrist, adopt a cat or dog from the street. On the streets pets live only two years average.

You really don't know what you are talking about. There are plenty of solid state amplifiers with massively overbuilt power supplies that also play louder than their power ratings suggest. Again, it's all about reserve power, and headroom.

Give a listen to a pair of old Mark Levinson ML-2 monoblocks. Rated 25 wpc and will play louder than any 50 watt tube amp. It all depends on the design of the amplifier, not the devices used.

JohnR · « **Reply #14 on:** 19 Dec 2010, 11:50 pm »

Quote from: TONEPUB on 19 Dec 2010, 11:48 pm

You really don't know what you are talking about.

Jeff - please refrain from delivering personal insults to AC members.

sebrof · « **Reply #15 on:** 19 Dec 2010, 11:52 pm »

The graph looks like the speakers are relatively easy for a tube amp to drive, although the phase angle graph would help as well.
Regarding watts - If I read your post right, you like your 55 SS watts. If that's the case, I suspect just about 55 tube watts is what you would want. Something like a Push Pull EL34 might be nice. Lots of those around.

srb · « **Reply #16 on:** 19 Dec 2010, 11:57 pm »

Quote from: TONEPUB on 19 Dec 2010, 11:48 pm

It all depends on the design of the amplifier, not the devices used.

You may be right, but don't be so hard on Fullrangeman. A lot of us get this information from the manufacturers of the equipment.

One manufacturer (here on AudioCircle) says in his website information that "Power [of this tube amp] is 35 watts per channel, but you can use it where you would normally use a 100 watt solid state amplifier." And this manufacturer also builds solid state amplifiers.

Steve

srb · « **Reply #17 on:** 20 Dec 2010, 12:00 am »

Quote from: sebrof on 19 Dec 2010, 11:52 pm

Regarding watts - If I read your post right, you like your 55 SS watts. If that's the case, I suspect just about 55 tube watts is what you would want.

As I mentioned in a previous post, Virtue Audio rates their TWO.2 for 44W @ 8 ohms with the 130W power supply.

Steve

FullRangeMan · « **Reply #18 on:** 20 Dec 2010, 12:01 am »

Quote from: TONEPUB on 19 Dec 2010, 11:48 pm

You really don't know what you are talking about. There are plenty of solid state amplifiers with massively overbuilt power supplies that also play louder than their power ratings suggest. Again, it's all about reserve power, and headroom.

Give a listen to a pair of old Mark Levinson ML-2 monoblocks. Rated 25 wpc and will play louder than any 50 watt tube amp. It all depends on the design of the amplifier, not the devices used.

Sorry again, your personal opinion is unquestionable.
These amps you mentioned are outstanding build quality, I could add Bryston too.
Regards, Gustavo

eclein · « **Reply #19 on:** 20 Dec 2010, 12:28 am »

Gustavo....Thank you for you kind help, I totally understood what you meant and enjoy reading your posts.

Steve...so I'm sorta right?

Like I said in the opening post, I love my setup, the Virtue gear I have will be with me forever, its great stuff and Seth is a class act. I am just curious how my beloved JBL's would sound with a gaggle of tubes driving the bus!!!! I'm the kinda guy that when I get interested in a hobby I try every part of it, I'll build speakers soon, then try tubes, was thinking about making a DAC with the same chip thats in my Piano M1 but need more knowledge first so I ask questions. My Dad is 92 and the smartest man I know, when I asked him how he got so smart he said "I asked a lot of questions" ...