R/E/P > Dan Lavry

can i swap a resistor for a speaker in a cabinet?

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Andy Peters:
Sin x/x wrote on Sat, 11 November 2006 21:28
You can also get more output stage (penthode) distortion if the amp has output tubes in parallel. Simply remove 1 half of the tubes and instead of the 8 Ohm trafo output you must use the 16 Ohm output.

... or you could just use an AC15.


Jon Hodgson wrote on Sat, 11 November 2006 11:22
danlavry wrote on Sat, 11 November 2006 00:40
iCombs wrote on Fri, 10 November 2006 22:57

My bad...I was talking 110-115+ dB SPL...stage volume.  Loud.  As I said before, I CAN'T speak to the noise reduction...but I don't give a rat's ass, either.  If I want to make my amp less noisy, I'll pick tubes carefully, make sure my cables are good, and make sure my signal chain is properly grounded.  Or I wouldn't turn my gain knob up so damn much.  I wouldn't buy a Hotplate for that purpose.  I've never even so much as looked at THD's lit on the thing...the guys at my local guitar shop (not GC...good high-end/vintage crazy shop...[url
http://www.solidbodyguitar.com[/url]) swear by them, and I've come to trust their opinions on a practical level as they have the time and resources to shake this kind of gear down.    

I cannot speak to the noise reduction issue, but I'd say that it's safe to say that no one thinks "noise spressor" and buys a Hotplate.  That said, perhaps a better look at the circuitry of the Hotplate is in order?

You seem to like the product and that is fine. With electric guitars I expect that people go for a lot of analog type of distortions, nothing new here. In fact, the amp distortion is part of the sound of an electric guitar, and I have no problem with that.

If no one cares about the "noise reduction" aspect, then why do the sellers of the product promote it as a noise reduction tool?

Personally, for me, I do have a problem with 110+spl. I know it is "part of a culture" to go to a rock concert, to a high
school dance and similar, where people blast their ears real bad. The long term outcome for such a short term "pleasure" is pretty sad. It really does not take much time at 110 spl to have permanent hearing loss.

Sadly, I know that my comment will do little good. People like fat food and loud music, and it is often not until after the damage is done that they realize it. This is not a top down lecture. I too did some real dumb things in my life, I was a heavy smoker and I did not eat well. It is sad to see a whole generation of Ipod users be exposed to such loud music.

Dan Lavry


I think you're missing the point a little.

Firstly with regard to levels, iCombs was talking about getting the desired tones WITHOUT those levels. The thing is that guitar amps tend to give the best sounds when they are being driven hard, but driving them hard usually means high volumes. One of the aims of units like the hot plate is to attempt to achieve those tones without deafening the guitarist.

Secondly as regards the "noise reduction", the problem with driving guitar amps really hard is that you end up with a lot of noise, this isn't really a problem when you're playing (since it's being masked by a signal that's choc full of harmonics), but is a problem in between notes. Given the choice between two otherwise equally good units, where one can reduce this problem and one cannot, you go for the one which reduces it, hence the feature and hence it goes in the advertising.

The information on THD's site is pretty clear on this, they say it reduces noise BETWEEN notes. It doesn't claim to improve signal to noise ration, because by definition there is no signal when there's nothing being played.

You might argue that their claim of noise reduction is incorrect with regards to engineering terminology, but it is NOT incorrect with regards to the English Language. Noise Reduction is by definition something which reduces noise, and cutting it during periods of silence, even if you do nothing anywhere else, is reducing it.

OK, you are correct that they are talking about "reduce the noise between notes". But reduce noise compared to what? The other leading product? It is very unclear to say the least.
Of course as an engineer I would prefer some noise figure or a plot for the unit between notes.  

Clearly, it is not engineering terminology. But it is also poor English description. It took you coming in here to explain to me that someone is trying to do their best to make sure that the tradoff between "tube saturation" (or whatever they use it could be a transformer or even a transistorized circuit) provides an acceptable balanced between saturation when the note is played, and noise between notes.  

You are in fact describing "less noise increase", not noise reduction, and even that is without a referance.

I can see that marketing would rather not say "less noise increase" when they can say "noise reduction". There is no noise reduction between notes. There is possibly "less noise increase" compared to some other product, which may have a lot of value to a user. I do not know all the products on the market. I do think it should be stated in a clearer way.

Dan Lavry  


Where I come from a basic gate removes noise and is a noise remover, not a reducer as the noise isn't removed but eliminated below threshold. However it only works when there isn't any keeper material, so it's effective at removing 60 cycle hum and the higher noise floor that amps exhibit in between notes where John correctly stated the noise is typically masked by the loud keeper notes, but the gate is never activated when the keeper notes are present, so noise removal does not take place while the guitar notes are sounding, otherwise it would remove the keeper notes. Modern gates have range settings which allow the gates to act like a low level expander. They attenuate the signal relative to range setting and thus are not true gates which mute the total signal route. Technically the Hot Plate folks are not gating if they are attenating the signal in between notes and I agree it points to a downward expander, which pushes low level signals down while leaving the main levels intact. Typically noise removal is a gate, whereas noise reduction can be based on various parameters from narrow band eq cuts where the noise range resides, to dynamic expanders that reduce noise on the broadband by attenuating lower levels at all frequencies. If the circuit has an expander involved that attenuates low levels by -10dB, than it qualifies as noise reduction.


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