Tube amp (Schiit Valhalla) in a drawer with no ventilation: Fire hazard or just fine?

[Entropy.]

Hullo,  

          I've heard a lot about how the Schiit Valhalla, among other tube amps, can get extremely hot while operating. Now, I've been looking to purchase one to add to a "minimalist" desk setup, to use with some Sennhesiers hd6xx's. Because of that I want to keep the amp tucked away in a drawer to keep my setup looking clean. My desk is made out of wood, which the manufacture lists as "Processed/engineered Wood." If it helps, It seems akin to oak or ash wood. I doubt the amp could reach a point where it could autoignite any wood, but still, I wanted to ask if having it in a drawer could pose a potential problem? I'll have basically nothing else in the drawer with the amp. Ty

[HumdrumPenguin]

45 minutes ago, Brok3n But who cares? said:

Hullo,  

          I've heard a lot about how the Schiit Valhalla, among other tube amps, can get extremely hot while operating. Now, I've been looking to purchase one to add to a "minimalist" desk setup, to use with some Sennhesiers hd6xx's. Because of that I want to keep the amp tucked away in a drawer to keep my setup looking clean. My desk is made out of wood, which the manufacture lists as "Processed/engineered Wood." If it helps, It seems akin to oak or ash wood. I doubt the amp could reach a point where it could autoignite any wood, but still, I wanted to ask if having it in a drawer could pose a potential problem? I'll have basically nothing else in the drawer with the amp. Ty

Send us a picture of the place where you intend to put the amp on. Nervetheless, I'd avoid living a tube amp in any area without ventilation. 

[H713]

Not a good idea. I'm not going to comment on whether or not it's a fire hazard, but it's going to absolutely cook that amplifier. The tubes won't care, but everything else will.

 

Is the appearance of that amplifier really that objectionable?

 

 

[Entropy.]

48 minutes ago, HumdrumPenguin said:

Send us a picture of the place where you intend to put the amp on. Nervetheless, I'd avoid living a tube amp in any area without ventilation. 

Will do, I might have to get back to you tomorrow, however. 

48 minutes ago, H713 said:

 

Is the appearance of that amplifier really that objectionable?

 

 

No, It's just that I said I'm going for more of a "clean" aesthetic- the amp does look quite nice imo however, it's just that I feel like there's no good way to integrate it with the rest of my setup. Do you think that the heat would disturb the operational lifetime of the product or do you think It'd just upright damage it? I mean worst case worse schiit has a five year warranty, if it ever dies on me because the heat I could be a dick and use the warranty, and not tell about where I put it, kek. 

[Entropy.]

1 hour ago, HumdrumPenguin said:

Send us a picture of the place where you intend to put the amp on. Nervetheless, I'd avoid living a tube amp in any area without ventilation. 

Untitled folder - Google Drive
sorry for the pictures lol, DWH this is 16x13x5 inches, with a very small amount of ventilation from the gap in between the top of the drawer, and the desk. 

 

 

R9b1827eba38c794a90099fbbd8bd2880.jfif

[HenrySalayne]

2 hours ago, Brok3n But who cares? said:

sorry for the pictures lol, DWH this is 16x13x5 inches, with a very small amount of ventilation from the gap in between the top of the drawer, and the desk. 

It's not going to work. But you also need a cut-out for the cables and you could add a fan to the back of the drawer.
Nevertheless, just get a solid state headphone amplifier. The only reason to get a tube amp in the first place, is the nice glow of the tubes.

[rice guru]

1 hour ago, HenrySalayne said:

The only reason to get a tube amp in the first place, is the nice glow of the tubes.

There are a few sonic reasons beyond that as well. 

 

3 hours ago, Brok3n But who cares? said:

Untitled folder - Google Drive
sorry for the pictures lol, DWH this is 16x13x5 inches, with a very small amount of ventilation from the gap in between the top of the drawer, and the desk. 

 

 

R9b1827eba38c794a90099fbbd8bd2880.jfif 1.65 MB · 2 downloads

I really would not put a tube amp in an enclosed space like at all if it doesn't start a fire you may end up just killing the amp 

[HenrySalayne]

7 minutes ago, rice guru said:

There are a few sonic reasons beyond that as well. 

We've been over this again and again. There is no inherent difference between a linear tube or transistor amplifier. Anything audible is caused by (intentional) "bad design" leading to colouration. The Shiit Valhalla is advertised as a linear amplifier and can be easily replaced with a decent solid state amplifier without any noticeable difference whatsoever.

 

This "If you want a decent amplifier you have to get something with tubes" is just wrong and there is nothing to back it up.

[HumdrumPenguin]

6 hours ago, Brok3n But who cares? said:

Untitled folder - Google Drive
sorry for the pictures lol, DWH this is 16x13x5 inches, with a very small amount of ventilation from the gap in between the top of the drawer, and the desk. 

 

 

R9b1827eba38c794a90099fbbd8bd2880.jfif 1.65 MB · 2 downloads

You'd have a hard time managing cables and changing volume all the time (since you're supposed to change volumes on the amp's pot, not on the software running your computer). Leave it on the desk, or think of another alternative that would go well with your setup that is within your budget.

[Entropy.]

4 hours ago, HumdrumPenguin said:

You'd have a hard time managing cables and changing volume all the time (since you're supposed to change volumes on the amp's pot, not on the software running your computer). Leave it on the desk, or think of another alternative that would go well with your setup that is within your budget.

Eh, I have a plan for cables, Volume, It shouldn't be that bad. Only concerned that the amp will fry.

 

9 hours ago, HenrySalayne said:

It's not going to work. But you also need a cut-out for the cables and you could add a fan to the back of the drawer.
Nevertheless, just get a solid state headphone amplifier. The only reason to get a tube amp in the first place, is the nice glow of the tubes.

I wouldn't say that a tube amp would make no difference at all, there's probably some traits that are easier to reproduce with tube amps rather than in solid states. Yeah, I've been considering something like a schitt stack with a loki mini+, who knows what I'm going to go with. 

[HollowSavant]

Mine gets "almost too hot to touch the volume knob" level of hot. I wouldn't put mine in a drawer, but you can always test it out. Reviews of the product show people having different experiences when it comes to the amount of heat it generates. I can feel the heat through the bottom of my desk when I touch it...
FYI, I also do what some consider a taboo and turn it off when I am going to be away from my computer for a few hours. Using it a little over a year, driving Fidelio X2HRs, with no issues. 

[rice guru]

10 hours ago, HenrySalayne said:

We've been over this again and again. There is no inherent difference between a linear tube or transistor amplifier. Anything audible is caused by (intentional) "bad design" leading to colouration. The Shiit Valhalla is advertised as a linear amplifier and can be easily replaced with a decent solid state amplifier without any noticeable difference whatsoever.

 

This "If you want a decent amplifier you have to get something with tubes" is just wrong and there is nothing to back it up.

thge inherent difference between a tube amp and a traditional non tube amp is one can use tubes or not tubes themselves change the sound signature. and depending on which group of thought within audio it can change stuff like presentation as well with tube rolling. different tube amp designs are more ennclined to tube rolling than other amps. I was also not at all suggesting OP get a tube amp at allnor was I ever suggesting a person needs a tube amp to get anything decent as I myself for a long time and to this day run a $100 solid state amp.

[H713]

As a general rule, vacuum tube based amplifiers will have higher distortion than solid-state amplifiers. Much of this is actually a physical limitation of tubes. Something like the O2 amplifier had hundreds of transistors in it. You can do it with fewer, but it's tricky to get ultra-low numbers without using a lot of devices. To get THD down in the .001% range, it's generally necessary to have a lot of open-loop gain. This allows for lots of negative feedback. That's how op-amps get their THD as low as they do. We are generally quite limited in how many triode (or pentode) sections we can use in a single chassis, however, as each tube takes up considerable space and filament power.

 

There is another issue that we face in trying to design a good tube power amplifier, and that's impedance. As a general rule, we're driving very low impedances. Even if you have 600 ohm headphones, that's a relatively low impedance by tube standards. Reasonably sized tubes tend to have a limited maximum cathode current. Those that have higher cathode currents, in almost every case, have very high filament currents as well. The 715C is a good example of a tube like this- it can handle 15 amps of cathode current (pulsed), but it's got an insane filament requirement.

 

If you try to get more cathode current out of a tube than it is intended, you run the risk of depleting the electron cloud around the cathode. With tungsten or thoriated tungsten filaments, this isn't really a big issue. Oxide cathodes are much more vulnerable to being "poisoned" by positive ion bombardment in this circumstance. This is a much bigger issue with transmitting tubes than with small-signal tubes, but even if we ignore this issue, trying to extract 20 mA from a 6SN7 is NOT going to result in a linear, low-distortion circuit.

 

The traditional solution is to use an impedance matching transformer. Transformers are not ideal, however, and good ones (with low distortion) are very costly. Just look at the prices on Lundahl or Jensen transformers.

 

OTL amplifiers, like the Valhalla, attempt to get around this by using beefy tubes without an output transformer, and it works... sort of. They still aren't much good with low impedance headphones. The Valhalla does better than a lot of them, but its still has a minimum output impedance of 3.5 ohms, and 14 ohms in high-gain mode (this is likely because they're reducing the amount of negative feedback applied in high-gain mode).

 

So tube amps almost always have higher distortion for the reasons specified above. The trick is that many find the distortion produced by most tube amps to be largely unnoticeable. If they do notice it, many consider it to be unobjectionable or even pleasing. 

 

I can attest that really good tube amps sound an awful lot like a good solid-state amp. The output impedance on the Valhalla is likely to be the most noticeable difference. With 300 or 600 ohm headphones it's unlikely to be super noticeable (that depends on the headphones, however), but with some low-impedance headphones it could be. 

 

 

 

 

 

 

[HenrySalayne]

10 hours ago, H713 said:

OTL amplifiers, like the Valhalla, attempt to get around this by using beefy tubes without an output transformer, and it works... sort of. They still aren't much good with low impedance headphones. The Valhalla does better than a lot of them, but its still has a minimum output impedance of 3.5 ohms, and 14 ohms in high-gain mode (this is likely because they're reducing the amount of negative feedback applied in high-gain mode).

I wouldn't be too concerned. A dampening factor of 5:1 already falls in the 'unnoticable' category. Current is mostly limited by the headphones impedance.

[H713]

39 minutes ago, HenrySalayne said:

I wouldn't be too concerned. A dampening factor of 5:1 already falls in the 'unnoticable' category. Current is mostly limited by the headphones impedance.

True, they have gotten it low enough to not be too big an issue. An output impedance of 3.5 ohms isn't great, but as you pointed out, probably not too noticeable. 

 

Now, they rate distortion into a 600 ohm load. I haven't had my hands on a Valhalla or Valhalla 2 for testing, but I would be willing to bet money that output power and distortion into low impedance loads is abysmal. 

 

In case you can't tell, I'm generally not big on OTL amplifiers, especially for low impedance headphones. To me, the technical downsides to an output transformer are a much better compromise than those made in an OTL amplifier. 

 

At some point, I may experiment with an OTL headphone amplifier using 6AS7s, possibly paralleling two sections. Super impractical, but it could perform acceptably well with low impedance headphones simply because the 6AS7 has such a monstrous cathode.

 

By the way, because someone is going to ask:

I mentioned the 715C in my last post, a tube that can handle 15 amps of cathode current during a pulse. These would NOT be a good candidate for any sort of audio amplifier. They have neither beam-forming plates nor a suppressor grid and they are very nonlinear. They were designed for use in radar pulse generators during WWII. That's why they can stand off 20 kV and handle 15A pulses. They're still very useful in certain laboratory applications, but not for linear operation.