humanflyz Posted September 14, 2007 Report Share Posted September 14, 2007 I recently became interested in transformer-based volume controls and want to learn about them. For example, what makes them different from regular passive pre-amps? And are there advantages to using one versus the other? For something concrete, I'm looking at ones offered by Promethus Audio for the sub-1k range, and the Sonic Euphoria models for sub-2k models. Quote Link to comment Share on other sites More sharing options...
aerius Posted September 14, 2007 Report Share Posted September 14, 2007 I'm somewhat drunk right now, so forgive me in advance if I don't make the best of sence. Ok, with a traditional resitive volume control, as in a pot or a stepped attenuator using resistors, the output impedance goes up when you turn the volume down, and the current it can pass also goes down when you do that. Which is bad because the more you turn it down, the harder of a time it has driving cables or whatever the hell's hooked up to it. Common effects are rolled-off highs, a dead & bleached sound, a lack of dynamics, and bad tone. A transformer volume control's different, as you turn it down, its current output capability goes UP and its output impedance goes DOWN, and that is a good thing. It helps preserve low level details, tone, dynamics, and allows it to drive cables & shit better. It'll also break ground loops, and that's also a good thing, no hum, blacker background, etc. Downsides. It's not going to have the super ruler flat frequency response of a pot or resistive SA, though with a good TVC the roll-offs or humps will be well outside the 20-20k audio range. Oh yea, there's also the autoformer volume control, which does all the same things as the TVC except it doesn't break ground loops, but it may offer higher resolution & detail. Quote Link to comment Share on other sites More sharing options...
philodox Posted September 14, 2007 Report Share Posted September 14, 2007 So if you listen to yo shit LOUD like me and post is OK?! Quote Link to comment Share on other sites More sharing options...
aerius Posted September 15, 2007 Report Share Posted September 15, 2007 In theory, but in practice, I find the TVC to be superior at all volume levels. Quote Link to comment Share on other sites More sharing options...
DigiPete Posted September 15, 2007 Report Share Posted September 15, 2007 Ok, so let me get this straight.... a. The pots and stepped attens suffer from rolled off highs, dead and bleached sound.... b. while the transformers are great, but do not have the ruler flat freq response of the pot or stepped atten... but above in a. you said that resistive volume controls suffer from rolled off highs, but in b. you say they have ruler flat freq response. Can't have both Quote Link to comment Share on other sites More sharing options...
n_maher Posted September 15, 2007 Report Share Posted September 15, 2007 Ok, so let me get this straight.... a. The pots and stepped attens suffer from rolled off highs, dead and bleached sound.... b. while the transoformers is great, but it does not have the ruler flat freq response of the pot or stepped atten... but above in a. you said that resistive volume controls suffer from rolled off highs, but in b. you say they have ruler flat freq If either of the above had rolled off anything that was to an audible degree it'd be measurable, right? I have yet to see information of any kind to support that a pot not to mention stepped attenuator has frequency response altering characteristics. Whether or not they affect the perceived sound is certainly something that I've observed but call me a skeptic to freq. response claims. Quote Link to comment Share on other sites More sharing options...
aerius Posted September 15, 2007 Report Share Posted September 15, 2007 I warned you it may not make sense as I was tipsy at the time. In an ideally designed system, where the stuff after the pot has a negligible capacitance and need for current, the pot will give a ruler flat frequency response without fucking up the sound. The problem is we don't have an ideal world, cables have capacitance, sometimes a fuckload of it, so do tubes (Miller C), MOSFETS (gate capacitance) and many other real world devices. That capacitance will require current from a low impedance source to overcome it, not enough current and/or output impedance from the source too high and the sound goes to shit, the highs get rolled off and the rest of the bad things I listed will happen. Quote Link to comment Share on other sites More sharing options...
philodox Posted September 15, 2007 Report Share Posted September 15, 2007 In theory, but in practice, I find the TVC to be superior at all volume levels. Yeah, but you'd die if you listened at my levels... Quote Link to comment Share on other sites More sharing options...
aerius Posted September 15, 2007 Report Share Posted September 15, 2007 His name is Phil! Quote Link to comment Share on other sites More sharing options...
philodox Posted September 15, 2007 Report Share Posted September 15, 2007 Well, I mainly just mean relative to aerius'. He listens extremely quietly... while I tend to listen at what others would term very loud. Not sure of the exact level though as I don't have a SPL meter. Quote Link to comment Share on other sites More sharing options...
Icarium Posted September 16, 2007 Report Share Posted September 16, 2007 I dunno man I've heard some of the legends involving the volume level at which Philodox listens at. I've heard his rig is constantly outputting volume so fucking loud that the mystical 2.3 Hz tone, which has been known to cause spontaneous boners to those that hear it (Even females) and take away the boners of those that have have boners previous to the tone hitting their inner ear, in a gajillion mile radius. That loud. I'll admit to have been hit by the tone myself (Probably from Philodox's rig) while leading an eyes open group prayer at church while wearing pants that have recently shrunk to over-drying. So inconvenient. So fucking loud. Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted September 16, 2007 Report Share Posted September 16, 2007 Constant impedance step attenuators are in fact available. Some of the goldpoint attenuators before mikhail bought the company were available this way. Requires twice as many resistors and twice as many rotary sections. And are basically twice the price. Quote Link to comment Share on other sites More sharing options...
philodox Posted September 16, 2007 Report Share Posted September 16, 2007 I've heard his rig is constantly outputting volume so fucking loud that the mystical 2.3 Hz tone, which has been known to cause spontaneous boners to those that hear it (Even females) and take away the boners of those that have have boners previous to the tone hitting their inner ear, in a gajillion mile radius. That loud. I'll admit to have been hit by the tone myself (Probably from Philodox's rig) while leading an eyes open group prayer at church while wearing pants that have recently shrunk to over-drying. So inconvenient. So fucking loud. Quote Link to comment Share on other sites More sharing options...
Icarium Posted September 20, 2007 Report Share Posted September 20, 2007 Mikhail bought goldpoint? Wtf. Quote Link to comment Share on other sites More sharing options...
Icarium Posted September 20, 2007 Report Share Posted September 20, 2007 I didn't realize that Mikhail had the capital to buyout a company. Quote Link to comment Share on other sites More sharing options...
philodox Posted September 20, 2007 Report Share Posted September 20, 2007 He bought it quite a while ago... I think he is looking to sell it again though, if he hasn't already. Quote Link to comment Share on other sites More sharing options...
fierce_freak Posted May 30, 2008 Report Share Posted May 30, 2008 I'm thinking about picking up a pair of autoformers from Dave Slagle over at intact audio. I'm trying to decide if 15 3dB steps is enough or if I should spring the extra cash for 24 2dB steps. Any thoughts? Quote Link to comment Share on other sites More sharing options...
fierce_freak Posted May 30, 2008 Report Share Posted May 30, 2008 lol, yes, much with the gooderness. my poor wallet, though also, the 24 step unit would have flying leads, and the 15 step would have bare bobbins that I'd solder wire to...so probably better to just go with the 24 step unit, anyway *wallet screams* Quote Link to comment Share on other sites More sharing options...
n_maher Posted May 30, 2008 Report Share Posted May 30, 2008 lol, yes, much with the gooderness. my poor wallet, though also, the 24 step unit would have flying leads, and the 15 step would have bare bobbins that I'd solder wire to...so probably better to just go with the 24 step unit, anyway *wallet screams* Holy heck, at that price I'd probably just go w/ an RK50. Quote Link to comment Share on other sites More sharing options...
fierce_freak Posted May 30, 2008 Report Share Posted May 30, 2008 It is expensive, for sure. I'm planning to place them right in my source (Buffalo -> IVY -> Autoformer, then split the output to pre-outs for my active speakers and a headphone output. Quote Link to comment Share on other sites More sharing options...
Jon L Posted May 31, 2008 Report Share Posted May 31, 2008 It's all true about various theories, but in practice, I still preferred resistor-based approach for *my* system, which is assembled to be passive-friendly. I kept the EVS Ultimate Nude attentuators (shunt type) after comparing to Bent Audio TVC (the upgraded silver TVC) and various tubed and SS preamps. The lack of extra interconnects and extra chassis/internal wiring really helps, too, b/c EVS is more transparent-sounding than even the Placette Passive, which uses the same Vishay resistor but requires another interconnect, chassis, etc. http://www.tweakaudio.com/Ultimate%20Attenuators.html Quote Link to comment Share on other sites More sharing options...
fierce_freak Posted May 31, 2008 Report Share Posted May 31, 2008 I'll take a look at that link soon. Thanks, Jon L. For my intended use, would a simple resistive control work? I want to pull a headphone output straight from the volume control (or should I place the volume control between the Buffalo and the IVY?) Maybe I should use the digital volume control for the Buffalo that the TPA guys are going to be putting together. Man, I feel like I'm not making any sense today...my mind has been melted by Lost. Quote Link to comment Share on other sites More sharing options...
spritzer Posted May 31, 2008 Report Share Posted May 31, 2008 Holy heck, at that price I'd probably just go w/ an RK50. Amen brother!!! Quote Link to comment Share on other sites More sharing options...
Jon L Posted May 31, 2008 Report Share Posted May 31, 2008 ...my mind has been melted by Lost. Hey, I've got it recorded on HD DVR. Will watch tonight, but man, I hope it's GOOOOD! Quote Link to comment Share on other sites More sharing options...
fierce_freak Posted May 31, 2008 Report Share Posted May 31, 2008 Brain. Melted. Quote Link to comment Share on other sites More sharing options...
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