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I would like to use my DV Mark Jazz 12 in bedroom volume level. What is the problem, one can ask, it is not a tube amp...
My reason: it has no master volume for the power amp, so it works always on max, which produces some noise (the max noise). The volume pot regulates the pre-amp, and when I turn just after a bit above the silence it is almost to loud (bedroom).
My idea is say half the power on the loudspeaker, then the noise will be reduced, and I also got some extra leveling range for the pre-amp volume pot.
I did my homework, and basicly familiarized myself with the master level concept, and also on the attenuators. The master leveling is ruled out, as the amp has no effect loop in/out and I do not want to hack into the amp. The attenuators seems to be way overkill this moment.
I am aware that the loudspeaker is a non linear load on the amp, where its impedance depends on signal frequency. My guess using the linear 8 ohm / 100W resistor serial with the loudspeaker will not hurt the sound quality and the pick attack only generaly will lower a bass (having similar effect when I lower the EQ bass)
Can anyone confirm at all is this an idea worth to try, or have some similar experience. Any thoughts appreciated
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08-28-2018 06:09 AM
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Try a 100W L-pad instead.
steven
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Many thanks. Obviously my homework was not grade A as I missed this thing. Now continuing... Any experience on the sound quality degradation? I am afraid there is a reason why others are using $500 - $1000 devices just to achieve the very same goal...
Originally Posted by stevo58
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Do you also use the amp to play out at normal levels? Or are there times when you need it louder? I know it's not what you asked, but I'm just thinking a quieter bedroom amp might be an easier solution.
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A series resistor can have more than one "technical" effects but with a solid state amp I'd expect just minor changes in the sonic result.
Quite diffetent situation with a tube amp...
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Attenuators are normally used with amps with tube output stages; solid state doesn’t seem to pair up well.
Also, there are fundamental differences between a tube and solid state amp, including the way the output transformer and the loudspeaker interact. The attenuators shouldn’t change this; it can change the entire feel of an amp. Solid state amps generally have no output transformer and the speaker is driven directly by the power transistors. Much of the circuitry in a good attenuator is there to make sure this interaction doesn’t get lost. Otherwise it’s easy enough to turn power into heat, which is basically what happens in an attenuator.
Solid state amps are much less dependent on the output stage as a tone-shaping mechanism; the power amp generally functions to make the already-shaped signal louder. So just turning it down has far less effect upon the tone.
Please note I said nothing about ‘good’ and ‘bad,’ I only spoke of ‘different.’ I’m not interested in tube vs. solid-state harangues. I’ve heard great solid state amps and horrible tube amps.
steven
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Attenuation at the speaker will not reduce noise. If it does anything to noise level, it will make it worse.
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Currently I use it only in bedroom volume. I am very happy with the sound quality. Originally Posted by Woody Sound
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OK, It seems it worth a try.
I found this one: Speaker L-Pad Attenuator 100W Mono 1" Shaft 8 Ohm
It is not clear how the heat will dissipate, no mention of cooling... anyway the amp is 45W and I will not dial over 12 hours.
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Are you trying to over drive the amp at bedroom level? You should not be trying to over drive a solid state amp. If it is too loud just turn down the volume. Originally Posted by Gabor
What kind of noise? Guitar amps should be quiet, especially solid state. All my tube amps are quiet. Originally Posted by Gabor
If the amp is too loud with the preamp volume up just a bit, turn down the volume on the instrument.
All amplifier gain stages run their full gain (amplification factor) all the time; how much level comes out depends on how much level is put in... putting attenuation on the output of a gain stage reduces the level from the attenuator, not the gain stage itself. Originally Posted by Gabor
Right, don't hack into the amp. Originally Posted by Gabor
That would present a 16ohm load to the amp's output stage. Originally Posted by Gabor
W=(V^2)/R watt equals squared voltage divided by the load resistance.
Without the added resistor
45=(V^2)/8
V^2=360
V=19 Volts (what the amp was spec'ed and designed to produce, may be maximum)
With the added resistor
45=(V^2)/16
V^2=720
V=27 Volts (well beyond what was designed, may distort heavily if beyond maximum)
How this might sound at less than rated power depends on too many unknowns to guess.
Maybe you could further explain what you want to do... playing at noise free quiet undistorted levels should be perfectly easy. Originally Posted by Gabor
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The heat dissipates over the ceramic body. If you turn your amp up all the way and the load down, it will get pretty hot, because - surprise - it is converting output power to heat. The more it converts, the hotter it gets. You want to mount it in a box.
By the way, I agree with Woody Sound - in the long run, you will be happier with a small bedroom amp. I’ve never heard an attenuator that really sounds good. I have a THD HotPlate here somewhere that I haven’t used in at least ten years, and that’s a fairly pricey bit of gear. The best attenuators for tube amps are reactive. I think Suhr makes one, and Aiken has info on building one. This has nothing to do with solid state amps. And I agree with pauln - I don’t understand why you think you need this.
Steven
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Thanks for all the answers,
Listening to the advise, now have the option to look for a bedroom amp, which is obviously an other topic.
Just for answering for Steven's last question and pauln:
1)
The shss like white noise is coming from the power amp, and constant level, regardless to the Volume pot (which levels the pre-amp), and of course regardless the guitar pot. Therefore in very low bedroom levels, the noise/signal quality is bad and disturbing. In normal volume pot setting the noise/signal is OK (as the noise constant), so leveling down this good signal we should got a low level sound with much more less noise.
2) It is very inconvenient to use the Volume pot when after the total silence and dialing up, immediately the next is almost too loud (for bedroom). So again, leveling down the final signal should allow the pre-amp Volume pot to have a bit more range to function normally in bedroom levels.
That were my reasons in more detail. If the amp would have a master volume, it would solve my problem, but it has no such.
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Since the noise is from the power amp (after the volume control) an L-pad should reduce it. As others have said, it might change the frequency response since you’ll be changing the coupling between the speaker impedance and power amp. I’d suggest trying to contact an engineer at the manufacturer to make sure your mod won’t hurt the amp. I wouldn’t expect it to though, as long as you ensure the load impedance on the power amp stays higher than 8 ohms at all L-pad settings. Originally Posted by Gabor
Solid state amps typically can tolerate load impedances higher than rated. Tube amps typically tolerate impedances lower than rated.
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The noise...
I would suggest that if the listening level you want is so low that the normal "blow" of an amp designed for stage performance bothers you, get a $99 MicroCube or similar amp dedicated for low level practice... about 1-2 watts.
"Leveling down" the final...
That is likely going to shift your volume knob problem from being a touchy volume level control problem to being a touchy distortion level control problem.
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Or a little Fender Mustang. The modeling amps have gotten quite good.
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Get the $12 attenuator.
My boy Dale bought 2 of them to control out of control guitarists (I may have been one of them)
When you got too loud, old Dale would just pot you down, no fuss, no muss! Worked GREAT!
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solid state amps can certainly have a large amount of noise and hiss...roland jc 120 is a classic case...known for that high frequency hiss...as are the smaller jc models...solid state certainly does not mean quiet
i used an l pad years ago on amps...it works, but don't run it too hard or too long....generally you want to cut some db...not in 1/2!!
also remember that an amp tone is combination of amp and speaker...once the speaker is not being driven in the same way, the tone will be changed
cheersLast edited by neatomic; 08-28-2018 at 05:49 PM.
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Just a nitpick, but when power is cut in half, that’s just 3dB. The OP’s objective is to reduce the amplifier’s noise, and 3dB isn’t really very much, since the ear compresses dynamic range. I’ll bet the OP is hoping for more like a 10db drop in noise (1/10th the power). Padding the output to achieve this would mean 90% of the power goes to heating the L-pad and 10% to the speaker. It might work ok at bedroom volumes, but it would make more sense to find a quieter amp or fix the noisy one. Originally Posted by neatomic
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Why not use the headphones output, either into phones or into a small self-powered speaker - you get both controllable low volume and no power amp hiss !
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That was my first try... Unfortunately the headphone out has the very same volume independent noise and the volume is incredible loud, so practically the exact same problem as with loudspeaker. Originally Posted by newsense
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Interesting - I've just taken delivery of a Roland JC-22, mainly because of the stereo capability. Like its bigger brothers in the JC series, it has some hiss from the power amp (volume knob independent) - but certainly no worse than my Little Jazz, which it will probably replace. It doesn't worry me when playing through the speakers. However there is absolutely no hiss on either the phones or line outputs, which allows me to play quietly sans hiss. The JC block diagram in the manual confirms that these outputs precede the power amps, whereas the DV diagram shows the phones output (but not the line out !), comes after the power amp.
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Thanks for the details. I can not find any line out on my amp... Originally Posted by newsense
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This owner’s manual shows line out. It’s XLR, so you’d need to run it to something with an XLR line-in input or use an adaptor if you only have a 1/4” jack input. I doubt the line out will drive a headphone, so you might need to run it into a small mixer or headphone amp. And the result probably won’t sound a lot like your DV amp, since what comes after the line-in is an important part of a guitar amp’s tone. Originally Posted by Gabor
http://www.dvmark.it/media/filer_pub...v_jazz_212.pdf
Last edited by KirkP; 08-30-2018 at 04:46 PM.
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Well, it's embarrassing my forgetfulness I mean. Originally Posted by KirkP
My excuse, that in my actual amp the "Line Out" label is a tiny vertical line, not as good visible as in the photo, so I thought XLS is a a Mike In... (and also, it was dark :-), and I could list many more excuses, for example...
Regarding the tone, although my understanding that in solid state amps the power-amp is not as tone shaping than in tube amps, still I agree and same time afraid of, that the loved tone will gone. Also we lost the cabinet and the loudspeaker interaction with the amp.
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I actually own a Fender Mustang I V2, that was my first try, now I have a comparison. I spent a year living together with it, so I had chance to play out all the combinations, with no success. Just after I got the DV Mark, instantly I felt, this is a new world. Literally, like Ferrari compared to a toy. This applies to the pure jazz tone, maybe with other tones there is no such huge quality difference. Originally Posted by stevo58
I know comparing the two amps is not quite fair, because of the price is $150 vs $450. Still the DV Mark is not in the high end price category like $2000 - $5000, so the extra $300 on top of the Mustang price is really worth it IMHO.
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