有源管箱衰减器 Ultimate Attenuator 介绍
有源 Ultimate Attenuator 介绍首先我未用过,也不是卖这个的.
因为见识有限,以前见过的管箱衰减器都是无源的.所以对这种新东西会有兴趣.
http://www.ultimateattenuator.com/index.html
内有足够信息.我贴点其中有趣的在下面.
用一个不精确但通俗的归纳就是--输出给喇叭的信号变少后经一个晶体管放大电路再送到喇叭. 而这晶体管放大电路得音量当然会很好调. 具体效果,各人自己看英文. 看来有优胜之处.
http://www.vintageamps.com/plexiboard/viewtopic.php?f=1&t=81179&sid=3f262b4a7596ef206bff914ae39546e3&start=45
Re: hot plate/powersoaks http://www.vintageamps.com/plexiboard/styles/prosilver_se/imageset/icon_post_target.gifby plexi on Wed Feb 11, 2009 6:56 am
I'verun many different, if not all the major brands of attenuators in mymany years of working with Vintage Amps. Of all those I've used, theygenerally have the same result. There is a flattening of brightness andan overall degradation of the sound quality. As transparent as thosebrands claim they are, I must be honest, there is no such thing as aperfectly transparent attenuator. There are a number of built inmethods as well to help tame amp volume levels. The first that come tomind are the brands using the Kevin O'Conner system, Power Scaling. My own amp line, Mojave has a system we developed called Power Dampening.This is a good way to go with a new amp but it does not help with avaluable investment grade vintage amp and I would never prescribe orendorse modifying a vintage quality amp with an internal modificationlike Power Scaling or Power Dampening or anything else for that matter.Its destructive and devalues the product. The best solution is to finda safe and palatable way of getting the volume and tone to a point youlike without ruining your amp. I do know that Mercury Magnetics doesnot want their OUTPUT TRANSFORMERS used with any attenuators. They havedone their own investigating and feel that running attenuation isdamaging to the transformers. I tend to agree with them since the truthis, the load is static and the transformer will not behave the samewith loads such as an 8 or 16 ohm resistor or even inductive loads. Thetruth is, they don't sound that good either. If your amp is set to 16ohms and your pumping 100 watts into a 16 ohm load attenuator, yourtheoretically matching your load to your amps Output Transformer. Thatis supposed to get you the correct frequency response and provide anatural effect. the truth is, that by the time you reduce the powerlevel to the point where your satisfied with the volume, your morelikely to be disappointed with the tone quality.
With respectto the Ultimate Attenuator there is a difference. The first palce thisdifference exists is the load resitor. The Ultimate Attnuator, alsoknown as the "UA" uses a 30ohm load resistor. I do not know exactly why that value was chosen, butI do know this. It's safer. A lot safer. Your amps power output is amathematical equation. If you match the load to the ohmage tap on thetransformer, say 8 ohms to the 8 ohm tap on the amp, your amp willprovide maximum power efficiency. That means it works hard and willpass the maximum current. That also means heat. Heat in the Powertransformer and the output transformer. That is because its passingloads of current. Dangerous for an old amplifier. This is not an idealscenario for a vintage Marshall. The older original transformers weresimply not designed for this kind of use or better yet "Abuse". Withthe Ultimate Attenuator, your amps current is reduced leaps and bounds.
For instance, if your amps set for a 8 ohm load, the UA is onlygoing to see a maximum of around 25 watts made by your 100 watt amp.That is because the load is approximately 4 times larger. The result isthe power amp is full throttle but the power output is low. That isgood. It saves not only your output transformer but your powertransformer. This is probably a good answer to the Mercury Magneticsconcern now that the amp is not actually making any where near its fullpower even though the power amp is full tilt. The power transfered fromthe amp to the laod simply cant be any higher then the equation allowsfor.
Now what about the tone. The load is so far mismatched, how can the sound be correct? The UA has a built in low impedancepower amplifier. The term low impedance means strong high frequencyresponse and with their well crafted internal audio coupling, they havemanaged to retain and preserve the sound quality while keeping the ampat a low volume. The reduction of actual power is safer and the audioquality is preserved and enhanced via the audio coupling circuitry aswell as the built in low impedance power amplifier, which does exactly what you need for low volume high frequency preservation.
Becauseof these two basic facts, the Ultimate Attenuator is definitely thesafest product you can use and it delivers that low volume sound withthe least impact which results in a very accurate quality of soundreproduction. For what its worth, this is just my opinion and myexplanation was provided here to try and help some of you understandthe way these things work.
Over the years, I have always toldmy customers that it was safer to use both a Hot Plate and a Variactogether. The reason was simple, you can knock down the volume with theattenuator but you need to lower the power that is fed to the amp whichresults in how much power is made by the amp to protect it fromcatastrophe. I also recommended that the customer not use his besttubes since a variac will lower the heater voltage and thus reduce thetemperature of the cathodes and that causes the preverbal Cathode Stripping, which simply put, ruins your tubes very quickly.
Ifyour using an attenuator at present, I strongly advice you incorporatea Varaic to dial back the power level the amp can make. Reducing thepower by 30 volts is enough to prevent catastrophe. The coretemperature of the transformers can get very high internally and thatwill melt insolation between wire and cause shorts. The attenuator thatis set way down for good volume control and even if it sounds good toyou will be absorbing full power. Full power means full throttle on thecurrent flowing through the transformers and full throttle on theinternal core temperatures, several hundred degrees F. That can damageyour amplifiers original transformers. Newer transformers like Mercuryhave developed improved insulation and with a quality improvement inover all design materials, they can withstand the increased coretemperature much better but it's still a risk not really worth takingif you can simply avoid it.
The UA offers a higher load to startwith and that makes it safer. You can mismatch a passive attenuator buyusing a 16 ohm Hot Plate or similar attenuator on your amplifiers 8 ohmoutput tap, thus reducing the power in half, but the mismatch and thefact that your using a passive system will further erode tone qualityif not dealt with some how. Again, the UA has adapted audio couplingand incorporates the low impedance power amp which resolves the toneissue.
I'm in no way claiming the UA is perfect but it does thebest job to my ears and technically speaking there is a safety factorwhich is worth considering especially if you want to keep those oldtransformers from blowing or over heating.
I was informed thatthere is a protection circuit to prevent a major issue if you plug upyour amp to the UA in reverse. That is to say you plug the output ofthe amplifier into the speaker output of the UA. That would result in aproblem if there were no protection for that. Thanks to Tone-Freak, Ihave made the correction to my previous comments that you could have aproblem with the UA because of its built in power amp. It's not anissue and that is very cool to know.
Sorry to admit it but I amguilty of this mistake. Thank God it was a passive Hot Plate. I didplug the amp into the speaker connection and the speaker into theamplifier input of the Hot Plate. There is no damage and no ill effect.The unit simply does not work as an attenuator. If you reverse thewires your back in business and all is well. one of the safer factorsof a passive system.
For the money and trouble of buying both apassive Attenuator and a Variac and the fact that you will have to lugaround an additional 13 pounds of iron using the variac and think aboutyour tubes dying off, It makes a lot of sense to stick with the UA. Theunit provides safety, good tone and you can use your best Mullard powertubes. The UA does have a 100 volt power outlet on the rear of the unitto allow you to run your amp 20 volts down for a good measure of safetyespecially if your using an old JMI that runs on 100VAC or 105 VAC.That goes for old Marshalls as well. We did many old Coffin logo, Blocklogo and Script logo Marshalls. They run exactly right at 240VAC but ifyou set them for US voltage, typically 105-115VAC on the back of theamps selector, they are over voltage at 120VAC. 100VAC is ideal for theolder amps and will keep those internal voltage low enough not to blowup your original capacitors. Just another good reason to have the UA.When you guys use your older Marshalls or Vox amps or any British ampthat was originally built for UK use, be sure to check this out or havesomeone check it out for you. You can see if your amps running hot buymeasuring the heater voltage on pins 4 and 9 of the pre amp tubes. Theideal voltage for the heaters is 6.3VAC. If your looking at 8 VAC,you've got a problem and your running the amp with a very high internalvoltage most likely. This is where a Varaic can help. It will lower thepower down until the amps running at 6.3 Volts AC on the heaters. Nowyou can see where your amps AC input needs to be. If it sits at 100VAC,then that is the input you can safely use. If the running voltage worksout to say 115 VAC input, your probably ok to just go ahead and run120VAC since the difference is not outrageous and your not jeopardizingthe amp. This is off topic but I mention it because the heaters reflectthe internal voltages. That is to say if the heaters are way high, thenyour going to most likely have very high internal voltages inside youramp and then your in danger of over voltage on the old capacitors andputting tremendous stress on older tubes and power output will increaseas well. Al these things are tied together. 看了半天，lz这文章下的实在难懂。但lz对这个理解可能要商榷：
实际衰减器主要要克服的是听觉曲线的问题，有源无源不是主要问题，但如果你在电子管回路中加入了晶体管，那是大忌讳的。专业的吉它手是不这样干的， 甚至，弹混网络都要求变压器藕合，我到原网站看了一下，没有这个论述，有时侯，这是商家的一种宣传，把一个简单东西搞得神神秘秘。 我刚看过这东西2个版本的图片,看完后不是一般的呕血.
是的,就是用晶体管放大电路,输出到喇叭时可选加入线圈和不加入线圈.
道理就是类似于所谓在晶体管放大器的输出并入变压器来实现 管味.
看到这里,熟行的应该明白他与被动式的比,起码可以说---各有优势.
回过头说,开辟了思路---这样也行.
至于好不好听---有或者说一众管箱爱好者的耳朵好不好---玩弄---
懂英文的自己上网搜索一下就知道了.
放一个价值不菲的分体---衰减后经 1 IC 晶体管放大器----接价值不菲的CAB
----这么说吧,CAB那部分的质量是一定存在的, 另外音源部分(对于晶体管放大)
也是足够管味的..
我到是有兴趣做来试一下.
不建议生产这类东西的来回帖(可以用马甲来讨论), 否则一不小心,砸到自己脚.
[ 本帖最后由 logicmj 于 2010-8-13 08:03 编辑 ] 英文水平低 是不是等于串了一个晶体管功放,然后再改变音量?就像van halen在机头后面接一个HH晶体管功放再到箱体一样?利用晶体管功放不受音量影响来做到不损失声音? 我看过他的售价USD 699.是要吐血。个人认为完全没有意义，花了那么高成本实际上就是一个胆石结构，那我不如直接买胆石。还便宜点。
[ 本帖最后由 kldguitar 于 2010-8-13 08:48 编辑 ] 您也起得挺早啊.按这个价格,其实就是一台功放了 上面贴的英文是一个用家说的,可参考.
产品的主页并没有具体描述.这东西应该是一个中国人发明的.
我是通过看照片说的, 我说的也不一定就正确.
正常来说,管箱的喇叭输出不能直接接晶体管音箱的输入的, 一定有其他改动(或者用了管箱的line out). 你说起van halen, 有很多van halen 的band房照片, 地上都有一个那种大型可调变压器, 在顶部有一个龙头开关状调节旋钮. 我不知他怎样用的
我的理解是最后你听到的是经过晶体管放大器的,调节音量是调节晶体管放大器的音量.-----注意这并不代表出徕效果不好---要自己试.
看到5楼的意见,这么说吧,
如果被动式衰减能一统天下的话,根本不会有这类东西的生存空间的.
你上网搜索一下评价吧. 卖得便宜,估计人人说声音 cheap.
我不清楚这些东西的价钱, 按它这样的外观, 好像比许多被动的都贵.
开放思维,用耳朵验证.
我上面也说了它有可能 " 玩弄 " 很多人,有其基础的.
[ 本帖最后由 logicmj 于 2010-8-13 09:00 编辑 ] 不但有起得早,还有没睡的.Van halen的设备图里,是把HH V800 Power Amp接在5150与箱体之间.但是看起来并不是直接连接的.这样应该可以在head作出合适的音色之后再用晶体管放大.不过既然能放大,应该也就能缩小吧.
http://www.guitargeek.com/rigs/img/v/vanhalen_eddie_1997.gif 变压器似乎是他在marshall时代用的,把电压调到90v来得到他的BrownSound van halen 的连接中,
最起码 palmer speaker simulator 是可以将输出到喇叭的讯号变少的.
对palmer不熟,不确定.
他这套, 我理解只是为了省mic .
带着这套,外场也全包了,声音效果会很稳定.
van halen 现在就是一个酗酒康复者,长期high gain abuser.
他的耳朵吗......
[ 本帖最后由 logicmj 于 2010-8-13 09:13 编辑 ] 原帖由 madchenxing 于 2010-8-13 09:02 发表 http://bbs.guitarschina.com/images/common/back.gif
不但有起得早,还有没睡的.Van halen的设备图里,是把HH V800 Power Amp接在5150与箱体之间.但是看起来并不是直接连接的.这样应该可以在head作出合适的音色之后再用晶体管放大.不过既然能放大,应该也就能缩小吧 ...
他讲的和这个是不同的，HH V800 power 是功放，他那个实际就是分压后接一个晶体管组成的EQ，（从中文理解，英文写得实在玄妙，不知所云）和价格一起考虑实在看不出他妙在那里，可能可以满足一部分人的猎奇心理。买东西我个人觉得是要买对的，不要买贵的（当然，如果大家都认为贵的就是对的，那我就太高兴了，直接涨价就好） 有源的将是王道，成本不会比无源的高多少，功能实用性大太多了
光是无级调节就比换挡式要灵活，若加上修饰补偿电路的话~~~~~ 洋货实在不能从成本去考虑定价,不过做得外观很复古.我也一直希望衰减能做成旋钮多一些选择. 实际大家过于迷信无级衰减， 我们本来是要推无级的，但是有一个问题，无级衰减器个人水平要高，要会调，有些人没耐心调，反过来说你机器不好，不是有人认为THD的也不好吗？档位的简单，调试方便，就那几个。 不用太费劲 UA还不错, 价格比Ho贵一些
这两种都是靠那个re-amplify的过程减少听到的tone loss
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