Gday.
I guess this isn`t a easy question to answer.
Remember i am a n00b, i also assume this is
valuable info. for those who just have entered the tube portal.
The question in itself, are quite simple:
What specs, should one look for, regarding tubes for high quality
audio reproduction, ect:
sonics/mid/bass/gain/microphoni, etc. I realy don`t know,
but are there any difference in tubes behaviour when it comes to dynamic headroom,? or are theese things more depending on
circuit/component quality.
I guess this isn`t a easy question to answer.
Remember i am a n00b, i also assume this is
valuable info. for those who just have entered the tube portal.
The question in itself, are quite simple:
What specs, should one look for, regarding tubes for high quality
audio reproduction, ect:
sonics/mid/bass/gain/microphoni, etc. I realy don`t know,
but are there any difference in tubes behaviour when it comes to dynamic headroom,? or are theese things more depending on
circuit/component quality.
Hi Geir
Some might not agree with this, but almost any valve can be used for audio... (ok, maybe a 5U4 wouldn't be so useful as an output stage..🙂 )
For sonics (bass, midrange, etc) you'll just have to go with what others have commented. IMO that has more to do with the circuit where the valve is placed, rather than the valve itself. A good valve in a poorly designed circuit will almost certainly sound terrible. Conversely, you don't need expensive valves for good sound.
For high gain from a single stage look for high mu (in triodes), or high gm (in pentodes). Getting more gain than you need is pointless (unless you're going to use NFB), because you're going to have to make other tradeoffs for higher gain. Just because the 12AX7 has mu=100 and the 6SN7 has only mu=20, it does not mean the 12AX7 will make a better driver stage.
Some valves (like the 5879, for instance) were designed for low microphony. Some manufacturer's valves are more microphonic than others. Unless you have them on hand to test, you'll have to go on what others say about microphony.
Another thing, for low noise - generally stay away from pentodes, and look for high gm (low rp) triodes.
Dynamic headroom is basically to do with the circuit. Also, the time it takes for the amp to recover from overload affects the sound and apparent power - that is to do with the circuit as well.
Some might not agree with this, but almost any valve can be used for audio... (ok, maybe a 5U4 wouldn't be so useful as an output stage..🙂 )
For sonics (bass, midrange, etc) you'll just have to go with what others have commented. IMO that has more to do with the circuit where the valve is placed, rather than the valve itself. A good valve in a poorly designed circuit will almost certainly sound terrible. Conversely, you don't need expensive valves for good sound.
For high gain from a single stage look for high mu (in triodes), or high gm (in pentodes). Getting more gain than you need is pointless (unless you're going to use NFB), because you're going to have to make other tradeoffs for higher gain. Just because the 12AX7 has mu=100 and the 6SN7 has only mu=20, it does not mean the 12AX7 will make a better driver stage.
Some valves (like the 5879, for instance) were designed for low microphony. Some manufacturer's valves are more microphonic than others. Unless you have them on hand to test, you'll have to go on what others say about microphony.
Another thing, for low noise - generally stay away from pentodes, and look for high gm (low rp) triodes.
Dynamic headroom is basically to do with the circuit. Also, the time it takes for the amp to recover from overload affects the sound and apparent power - that is to do with the circuit as well.
Gday.
Ok.
Is there a wiki around here at diy.?
If not, I assume it would be quite handy to have.
Most ppl. here, do know the way around, but for newbie`s,
it would bring a site with good info on everything
worth knowing about tubes and circuits.
Am thinking not only a primer, but also a more basic
compendium on valves and there field of usage,
evt: pre:line and phono, R2R, power amps etc.
I am quite convinced there are several ppl. here,
with a lot of knowledge.
A wiki, would offer everyone a chance to share that info.
Does it sound good.??
🙂
Ok.
Is there a wiki around here at diy.?
If not, I assume it would be quite handy to have.
Most ppl. here, do know the way around, but for newbie`s,
it would bring a site with good info on everything
worth knowing about tubes and circuits.
Am thinking not only a primer, but also a more basic
compendium on valves and there field of usage,
evt: pre:line and phono, R2R, power amps etc.
I am quite convinced there are several ppl. here,
with a lot of knowledge.
A wiki, would offer everyone a chance to share that info.
Does it sound good.??
🙂
wiki
I am also new to tubes, and would love some wiki info.. However, the sticky tubes at the top of this forum are a useful place to start. One thing I'm looking for is reviews of different tubes. It's subjective, but that's fine. How about a page in the wiki in which people give quick reviews of varous tube types? maybe a good cirucit for that tube can also be posted?
should I set up a template in the wiki?
I am also new to tubes, and would love some wiki info.. However, the sticky tubes at the top of this forum are a useful place to start. One thing I'm looking for is reviews of different tubes. It's subjective, but that's fine. How about a page in the wiki in which people give quick reviews of varous tube types? maybe a good cirucit for that tube can also be posted?
should I set up a template in the wiki?
I'm unclear on the concept. The notion that one tube is "better" than another in some Platonic sense confuses me.
Q: What's better, a 42 tooth nylon gear or a 25 tooth brass gear?
A: Depends on what you're trying to do.
Q: What's better, a 42 tooth nylon gear or a 25 tooth brass gear?
A: Depends on what you're trying to do.
of course there are no absolutes, but I think it should be possible to get some consensus. There may be some that majority of people think are terrible (or maybe not, which could be telling) and some that the majority of people think are good, or at least usable. I agree with the notion of trying various flavors, but it has to start somewhere. Given the multitude of tube types, and several manufacturers of each, we are talking hundreds of experiments. Let's get a starting point.
Using your analogy, a fair statement might be that the nylon gear may be quieter than brass, but should not be used under high stress, and should not be meshed with a metal gear. Maybe brass should be used instead of steel if it is under water. # of teeth might depend on size, material, ratios.... There may be exceptions, but I think most people would agree with statements like these
Using your analogy, a fair statement might be that the nylon gear may be quieter than brass, but should not be used under high stress, and should not be meshed with a metal gear. Maybe brass should be used instead of steel if it is under water. # of teeth might depend on size, material, ratios.... There may be exceptions, but I think most people would agree with statements like these
When it comes to output tubes' sound, I believe that, generally speaking, the higher the plate voltage the tube has been designed to work with, the easier to get a good sound.
I think this is a consequence of the small influence on the anode gradient due to the swing on the plate load .
That might explain why the 845 - 211 and similar high voltage tubes ( over 1 kV ), have such a good reputation.
Or am I wrong ???
If so, someone let me know.
However, for a newbe, such choice is out of question, due to the lethal dangers implied.
With regard to driver tubes, this also applies, to a certain extent.
I think this is a consequence of the small influence on the anode gradient due to the swing on the plate load .
That might explain why the 845 - 211 and similar high voltage tubes ( over 1 kV ), have such a good reputation.
Or am I wrong ???
If so, someone let me know.
However, for a newbe, such choice is out of question, due to the lethal dangers implied.
With regard to driver tubes, this also applies, to a certain extent.
[QUOTE
Another thing, for low noise - generally stay away from pentodes, and look for high gm (low rp) triodes.
[/QUOTE]
Hi there....Ummm your'e taking me on with this one......have you considered the benefits of a pentode strapped as a triode ? I use EF86's and so many others this......far better bandwidth is obtained and tube spread characteristics are more evened out.
The ECC88 is an excellent sounding little tube ((high gm (low rp)) but beware using it with poor/long decoupling.... it can oscillate quite nicely into vhf.
rich
Another thing, for low noise - generally stay away from pentodes, and look for high gm (low rp) triodes.
[/QUOTE]
Hi there....Ummm your'e taking me on with this one......have you considered the benefits of a pentode strapped as a triode ? I use EF86's and so many others this......far better bandwidth is obtained and tube spread characteristics are more evened out.
The ECC88 is an excellent sounding little tube ((high gm (low rp)) but beware using it with poor/long decoupling.... it can oscillate quite nicely into vhf.
rich
And don't forget that pentodes have tremendously greater gain, AND don't forget how much noise matters in absolute terms (I have a pentode front end in Frankenhouse, can't hear a darn thing when I stick my ear in the speaker!).
Tim
Tim
Four stage!? That thing must require an immense amount of gain. It's going to hiss one way or another.
No......the driver stage doesn't have much gain (10dB) as it's really a current dump driver for 8x Kt88's in fixed bias.....(I consider the direct pent anode connection to the grid of the triode concertina phase splitter really as one stage as it has zero phase shift..i.e 4 stage really 3.)
For drivers I'm using 2x ECL82 penny strapped as a triode with a CM cathode resistor......this stage sucks about 2x17mA i.e 35mA at 360V B+. Musically this tube is darned good sounding. The amp THD is lower than 0.25% for 140W at all audio frequencies. I really ought to post the schematic...as it's really so easy to make...but still working on it. I think the fault many make with tube amps is underestimate the driver stage...one that doesn't keep the o/p tubes under grip.
rich
For drivers I'm using 2x ECL82 penny strapped as a triode with a CM cathode resistor......this stage sucks about 2x17mA i.e 35mA at 360V B+. Musically this tube is darned good sounding. The amp THD is lower than 0.25% for 140W at all audio frequencies. I really ought to post the schematic...as it's really so easy to make...but still working on it. I think the fault many make with tube amps is underestimate the driver stage...one that doesn't keep the o/p tubes under grip.
rich
audiousername said:
Of course, not all pentodes are noisy. Amperex quotes Req for the 6922 at 330 ohm, while the quoted Req for the E180F by Philips is 330 ohm.
The thing is, some people seem to dislike pentodes, for one reason or another. I quite like them myself, and use them quite a bit. Ordinary triode input stages get a little boring...
Ordinary triode input stages get a little boring... I couldn't agree more.....you won't find the ECC83 in my armoury.....
rich
rich
Hi there......the villians in amps which used ECC82/3 en masse (and there were alot of them) sounded right when the NOS or sim tubes were fitted. The GEC KT88-50W amp had a changed sound for the worse when I put rebranded Bentley tubes in lieu. The 88's weren't the culprit, but the see-saw or floating phasesplitter used brought out the deficiencies of this type of circuit. It's simplicity was it's bonus! The famed Mullard ECC82's were known to be low noise............and later on many clone manufacturers found it very hard to meet the Mullard specs. In some cases I've often found a 6SN7 quieter than an 82 and in frustration cannibalized the chassis to fit it the int oct. It looks more grandee.
There is still amps in production (europe) which use an ECC83 with 150K load as a tube driver driving a KT88.....what a scandalous waste of un-utilised bandwidth ;-6dB at 15Khz ! So much for lousy circuits for stability.Perhaps we shouldn't blame the tubes afterall.
rich
There is still amps in production (europe) which use an ECC83 with 150K load as a tube driver driving a KT88.....what a scandalous waste of un-utilised bandwidth ;-6dB at 15Khz ! So much for lousy circuits for stability.Perhaps we shouldn't blame the tubes afterall.
rich
Evaas said:
Of course they can be made to sound good, it's just that (as Rich has said) they are so often misused....
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