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On Fri, Aug 10, 2012 at 1:03 AM, Music Electronics Forum <email@example.com
Enzo has just replied to a thread you have subscribed to entitled - attenuation experiment, lack much theory, would like opinions - in the Music Electronics forum of Music Electronics Forum.
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Well here, let me confuse you further. It is one thing to reduce the sound level without changing the overall freq response, but your ears are not linear either. Go google up "fletcher-munson curves" to see how your ear responds. That is why stereo receivers have a "loudness" button. The less loud a sound is, the more limited is your ears' response to it.
And remember that in a guitar amp, the single largest variable in tone is the speaker. And once more, speakers are not linear either. They are mechanical systems, and can respond differently when run at polite levels versus when they are run LOUD.
Please be sure you understand the use of the term frequency here. A-sharp is a note, it has a frequency, same with B-natural. And all the others. The frequency is the note, or vice versa. All your EQ and tone controls and speaker effects change the frequency RESPONSE, meaning that in one system, given a dead even input, maybe the A-sharp comes out a bit louder than the B-natural, while in another system the B-natural comes out a shade louder than the A-sharp. However, in none of them is the B-natural turned into an A-sharp. If your guitar is in tune, and you change amp and speakers, the guitar will still be in tune, even if the tone is different. Frequency is the notes, frequency response is the relative loudness of each note compared to the others. Your tone controls or your attenuators or anything else that changes the sound will not change the frequency of the sound, it will change the frequency response of the sound. SO an active circuit can boost a frequency relative to another, not boost frequency. You turn up the treble control you get more treble, not different notes of treble.
I had an Ohmite wirewound rheostat, brand new, checked out for accuracy at 25 Ohms. I tried this alone(adjustable power resistor).
HOW did you try it? If you put it in parallel with a speaker, it won;t have a lot of effect, put it in series with a speaker it will have a larger effect.
Resistors are fine attenuators - electrically. WHy do they sell fancier things than resistors? Because they can. Every one of them touts itself as the best in some way. But really, the amplifier and speaker work together, they react to one another. An amplifier reacts differently to a speaker than it does a resistor. Those fancier attenuators have L and C elements addded in to make the amp react more like it does to a speaker, because a speaker is not a pure resistance.
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G'day Chuck.Thanks for the return on the "one too many project' ! Headphones aren't really a concern. My set-up(HT-1R) with
speaker emulatro/headphone jack, and 32 Ohm headphones with 20hz to 20,000 hz response don't teally sound bad. They DO sound different from the sound coming out of the Weber cv8a 8" Alnico I put in the Blackstar. Since giving up on Blackstars warranty crap, and re-tubing/speaker change, the amp has zero tone issues for me. I still don't like the fact that on the clean channel at full volume there is no sign of. overdrive/clipping/distortion/added sustain.this s contrary to what i was told by Blkackstar's chief technical engineer. Change channels, and immediately you hjave very noticeable distortion. There was supposed to be a smooth transition between fully craked clean channel and the
high gain channel at low volumes. On the high gain channel (actually Blackstar says this channel is not "high gain") a 40% increase in volume causes the distortion to be "so much thrash metal dissonence in my opinion. The headphones react much the same way.However,
more than that it just seems that they have a high degree of "brightness'.Although 20hz-20,ooohz sounds great, I,ve seen no graphical representation of just how linear that response is. perhaps the phones merely do a better job on the high mids and up. The tone is not untolerable though. it is really amazing what different tubes can accomplish. i did a lot of study to arrive at my choices to replace the cgeap Sovteks tht originally came with the amp. I ended up with an Electro-Harmonx 12 ax7 gold pin for the pre-amp position, and a JJ 12au7 gold pin for the output tube position. This change caused an immediate improvement in tone at all volume levels. When I installed the Weber speaker the tone became immeditely "warmer" or"browner" just as their description of it had stated. The Blackstar is as good as it's gonna get cause I'm not about to touch anything else inside that 90% s.s. mess. I'm heading toward that MOD 102 all tube build, and when I have completed it, there will be a great deal offered on one Blackstar HT-1R/modified-tubes and speake). The tubes ran me $45.00 and the speaker was $50.00. I'll probably tale $100.00 for the amnp that retails at $259.95-$299.95. If I can't get that, I'll go as low as $50.00, or I'll junk it for parts. Thanks for the replies and everything that you've sent me.I stilll need to print off the circuitry and set down to ponder it well.
I always think best setting down, and do my best back-pedaling on my feet. I hope you have a great day doing what you like best.