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89 db is it enough ?

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Hi everione,
I'm new to this forum and (almost) new to DIY tubes. I would very much appreciate if you would gave me opinion on the following:

My room is of a moderate size 10' X 24' X 9'. My speakers are old Altecs Lansing 1012 with sensitivity of 89 db. I'm thinking to build SE but I'm not sure if 4-5 W would be suficien to drive this speakers. Altough, I have built a tube preamp before I don't have experiance with tube amplifiers.
Also, if somebody would sugest output tubes for this project. This is my first project so I don't wont to start with something very expensive and complicated. I'm not very much interested in kit building. Thanks for your help.
 
If you listen to music very quietly, you might get by. But let's see how limited this setup is. Let's assume that when you say "89 dB" you're saying "89dB/2.83V/m." And let's further assume a frequncy region where the impedance actually looks like 8 ohms. In that region, 1 watt will give you 89dB at a meter, 4W will get you to 95dB on peaks. Move away to a more reasonable 2m listening distance, and the peak SPL drops to 89dB. That's not terribly loud and you're running the SE amp in the power range where its distortion performance is likely to be terrible. And remember, these are PEAK sound levels, not average- the average SPL is more likely to be 20dB or more below this, say 65-70dB.

Two solutions: more sensitive speakers (like 95dB/2.83V/m or better) or an amp with decent power and distortion performance (i.e., not SE).
 
SY said:
And remember, these are PEAK sound levels, not average- the average SPL is more likely to be 20dB or more below this, say 65-70dB.

If one listens to mostly modern pop music, you might be able to get away with only 4-5W. The difference between average and peak levels nowadays is strictly much less than 20db and usually less than 10db. I was happy enough with 89db/w/m speakers and 3W 90% of the time. My room is a little smaller and I'd say I listen at a slightly lower level than most other audiophiles.

If you have more omnivorous tastes and in particular if you listen to large scale classical it wont be anywhere near enough - IMO.
 
I've got some slightly "power-hungry" speakers,(not sure of the efficiency,they were homebrewed by my father 20+ years ago,he said the efficiency was kinda low.) and I use a PP 6V6 amp (~8wpc,before any real signs of distortion.) and have plenty of volume.Granted,my room is fairly small,at something like 12'x12',but it can rock the house!
I'm the type of guy who likes to occasionaly listen to Metallica or Pantera at concert-volume,and even with only 8wpc,in a smaller room,it's loud enough to get there! Not to mention it sounds good! ;)
(Yes,even Metallica and Pantera can sound good through tubes!)
 
MlinarS said:
...My room is of a moderate size 10' X 24' X 9'. My speakers are old Altecs Lansing 1012 with sensitivity of 89 db. I'm thinking to build SE but I'm not sure if 4-5 W would be suficien....


As everyone else has indicated it really depends on how loud you like to listen. My current tube amp is 8W (probably 4.5W RMS) per channel. I initially listened to it using a pair of Advent/1 speakers which I believe are between 87 and 89dB 1W/1M. For me, in my listening room (13' x 18') 8W was plenty.

I'm currently collecting the parts for a pair of SE monoblocs that should have about 4 or 5W (3W RMS). For probably 90% of my listening (maybe more) 4W should be enough if I used the Advents.
 
HOW MUCH POWER?

Let's make things clear -- if your loudspeakers are 89dB/W/m, and the room size is the stated -- 4-5W are quite enough, unless you listen to headbanger music or whatever!

Secondly, let's make things clearer:

Two solutions: more sensitive speakers (like 95dB/2.83V/m or better) or an amp with decent power and distortion performance (i.e., not SE).

More sensitive speakers is not the issue here! The guy already said his speakers are defined (maybe one day he will change);
further, more efficient speakers are a compromise road, just like any other.

Decent power and distortion performance? Not SE? What is this about? Do I feel bad vibes about SE? Well, if it was a garden variety SE, meaning 300B with 8-9W per channel, it would have both enough power (more than 4W) and distortion performance (all lovable 2nd order) and a sound better than the guy has ever heard in his room!

What is it that PP could offer, especially to a novice? I know that "de gustibus nihil discutandum est" -- but guys, that was a question from a novice, give him a break... and some credit!

When it comes to 4-5 (and more) W of SE power, with decent distortions etc. -- those who have not yet done it, might take a look at my site (before I close it for renovations, i.e. adding new designs). The site is as listed below the reply.

Regards to all!
Aleksandar
 
Thanks everione for repply. Sorry I didn't mention that I live in the appartment so the loud listening is out of question. The music I listen to is Lorrena McKennit, Diana Krall type and some clasical music.
....i think EL 84 would be a good start.....

I was thinking about this tube to.


...more sensitive speakers (like 95 dB/2.83V/m or better)....

The speakers I have are temporary solution 'til I faind somebody here in HK to build boxes for a new speakers I'm planing to design. ( I recently moved to HK from Canada, temporary).

...If this is your first project I would definetly recomand an SE amp....

This is exactly reason I was thinking about an SE.


Thanks everibody for replies.
 
89dB etc

I use 89 to 90dB speakers in a room 18ft x 14ft, driven by a 300B SET which gives
6.5watts (measured). This is a bit lower than the normal 8watts, due to having the
OPT set to 5kohms rather than the more normal 3kohms. I believe the gains in
sound quality are a good tradeoff for the minor (in dB terms) power loss.

I have no problem with volume levels at all. In fact, I can listen fairly comfortably
from an adjoining room.

Now my 300B amp was designed to give good dynamics, with a seriously
strong driver stage; I'd say that this makes as much difference as say a doubling
of output power. This amp has its own PSU for the driver; this is a tridoe/pentode
mu stage with low output impedance and wide voltage swing of +/- 150V; and
it has its own PSU of adequate voltage for the mu stage (490V).

I just had to post when I saw you mention Loreena McKennit!
Mmmmm, she is a great favourite of mine.
Please please please hear her though a nice SET amp!
Oh, the lovely delicate subtle nuances to her singing; the expression of her
near whisper; and then when she so smoothly transitions into full singing and
of such quality, it makes my spine tingle!
It just has to be a 300B SET (in my biased personal view) to really get all this ...:)
 
Agreement...

Hi to all...

Well, Loreena McK... I did not yet have the chance to listen to her music... or was not aware of that. Diana Krall and the rest, OK (let's call that garden-variety in the best sense of the term, just like 300B SET is garden-variety... :)

In full agreement with Mike C -- go for SE, it's simpler. If you want to make something cheap (not cheap as not valuable, but cheap as it-will-not-cost-an-arm-and-a-leg) go for one of the designs on my site (www.tubeaudio.8m.com) and you will not be disappointed.

Mike C -- you could extract the few missing watts by simply higher B+ since you are most probably running too few V across the tube and a higher (my choice exactly) Ra does not allow more power than what you get unless there is more V flowing across the tube... if you have already reached full dissipation, decrease the current a little. That is, if you need the extra 2W you could get out of it...

Regards to all,
Aleksandar
 
Loreena McKennit

Her defintive albums are 'The Visit' and 'the mask and mirror'.

The music isn't to everyone's taste, but if it suits you, you will go weak and
wobbly at the knees while swooning with pleasure.

Re my 300B amp - yes, that's a good suggestion about raising the B+.
I'm running with 365V B+ with fixed bias, so about 345V across the 300B and
68mA; 24 watts.
I believe the TJ's I'm using are good for 27 watts dissipation so I can tweak them
up a bit. Easiest to try a bit more current, but more voltage may indeed give a
better result. Not hard to do this by adding a small cap across the 1st one in the PSU.
I'll try it when I get a chance; thanks!
 
Alex Kitic said:

In full agreement with Mike C -- go for SE, it's simpler.


From everithing said here I think I'm going to be OK with SE. The only question now is how expensive should I go.

Mike C said:
Her defintive albums are 'The Visit' and 'the mask and mirror'.

In addition to this two I have "The Book Of Secrets" but my favourite is "The Visit".

Mike, if you don't mind me asking, what is your impression of TJ 300B and what are you using to drive TJ's.

Is there any site with revue on different brands of 300B's.

Thank you all.
 
TJ 300B

I like it a *lot* but I've only ever compared it to the cheap Valve Art 300B, and I
have never heard another 300B valve or amp in my life so that shows just how
little I know!
My amp, with the TJs, is fast, clean, has good dynamics, pace, rhythm, drive.
Subjectively, it's the most powerful amp I've ever owned - is that weird or what?
I'd say it has the SET sweetness, but not 'added' sweetness; just a lack of
harshness. Very musical with it - it certainly makes ones feet tap.
And of course- emotionally persuasive in a big way!
How much is due to the amp and how much to the TJ's I can't say, but I have a
sound that I love to bits. Party that's luck but mainly it's from the great advice I've
had from people here and on Tube DIY Asylum.

There are several reviews of 300B's out there, eg on the SET Asylum. If you
search the web for '300B shootout' I'm sure you'll find lots of information.

My driver stage is a 6SL7 (both halves paralleled) with active load; using an
E83F pentode load (Kimmel mu stage circuit). This is highly inspired by the
Welborne Laurel amp - same circuit, different pentode.
The E83F seems to be a good musical small signal pentode.
I think I've improved on the Laurels by using a separate PSU for the driver stage.
To run the valves with decent voltage, and allow a wide signal swing, needs
a lot of B+ and that's what I did; about 490V.
The 6SL7 is a very linear valve with wide voltage swing. With about 220V on it,
active loaded, it will go 150V either way and be exceptionally linear. It's also
good sounding, and there are several to try to fine tune the sound.
It just doesn't have anything like enough current to drive a 300B properly, but
in my case this is overcome first by parallelling up the halves, but mainly by
using a pentode active load. Works a treat.
Do note, there are *many* types of driver stage; all are equally valid, all have some
advantage.

For my next amp I may try a different triode, perhaps one of those special 7 pin
single triodes of high gain and good Gm; but I'll probably go for a pentode load
again. Oh, and I really want to try a grid choke ....
 
2 cents..

From everithing said here I think I'm going to be OK with SE. The only question now is how expensive should I go.

The question will depend on how much do you want to invest for the rest of the system. I would suggest 300B or 2A3. Use cheaper chinese tubes, it sounds just as good as those NOS tubes. You can upgrade it easilly when you win a lottery later.
If you are adventerous enough you can try other tubes as well. But with your speakers (89db) you are limited to small number of choices.
Cheapest SE design I know is using the ecl82 or ecl86. And sounds better than most SS amps. Recommended as a first project
 
Chinese vs. NOS

Beside the fact that all of you seem to be just fascinated by standard DHTs -- 300B and 2A3 -- completely forgetting that excellent and interesting and different (since everyone's dream, thanks to good marketing practice, is having a DHT amp) SE amps can be built both with IHTs and tetrode/pentode tubes, at that, costing a fraction of the price...

Actually, a quote like this one says it all:

I would suggest 300B or 2A3. Use cheaper chinese tubes, it sounds just as good as those NOS tubes. You can upgrade it easilly when you win a lottery later.

If you have not had the chance to try i.e. NOS 6B4G with black anodes etc. vs. Sovtek or similia (Chinese, etc.) you just cannot know that the difference is HUGE. The same is unfortunately true of other tube types as well... NOS sound generally MUCH better than current production (excluding special tubes like KR etc. that seem truly pieces of art to me, although I have not had the chance to try them, so until I try I cannot say).

Therefore -- WE300B is waiting for you! Eventually, various Vaic or KR tubes... alternatively, you could go on a different path without wishing you had won the lottery and enjoying NOS sound.

Regards to all,
Aleksandar
 
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