Audiophoolery - Page 1
Forum section: electronics / projects

author: jwflammia
author_rank: Newbie
timestamp: May 07, 2016, 01:01:03 pm
content: check this crap outhttp://makezine.com/2016/05/06/warm-tube-tone-is-just-what-the-raspberry-pi-has-always-been-missing/

author: stmdude
author_rank: Frequent Contributor
timestamp: May 07, 2016, 01:11:08 pm
content: Phoolery?We're not talking directional cables or $500 wooden knobs for your amp here.It seems like a decent product for a decent price for people that enjoy that particular type of distortion.. Or am I missing something obvious here?

author: suicidaleggroll
author_rank: Super Contributor
timestamp: May 07, 2016, 01:12:17 pm
content: I don't see what the problem is. Why do you think this is "audiophoolery"? I don't see anything impossible or misrepresented and the price looks appropriate. Tube amps DO sound different than solid state, and some people prefer them, what's wrong with that? Sticking it on a Raspberry Pi might be a little...odd, but there's no "audiophoolery" at play here that I can see.

author: Audioguru
author_rank: Super Contributor
timestamp: May 07, 2016, 01:22:52 pm
content: An amplifier spec's should show its frequency response (the output transformer for the vacuum tube probably cuts lows and highs).The spec's should also show distortion at its rated output level and load impedance (a single vacuum tube amplifier produces many even harmonics).I think a vacuum tube amplifier compresses loud levels somewhat because it has soft clipping.Then the audiophools think that the bad "telephone" sound quality is warm.

author: jwflammia
author_rank: Newbie
timestamp: May 07, 2016, 02:13:58 pm
content: What 's the tube for. It needs at least 100vac to work. Where is that coming from?

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: May 07, 2016, 02:23:36 pm
content: Quote from: jwflammia on May 07, 2016, 02:13:58 pmTry reading what you linked:"At first I shuddered at the thought of using tubes again, but after looking into it I found a number of low-voltage tube designs that folks seemed to really like. ""I was not a big fan of the tube sound in general, never mind one that runs at such a low voltage (for tubes). "They're probably running some variation of the classic PAIA "starved tube" configuration.http://www.paia.com/ProdArticles/tubesnd.htm#tubeworkPS: Why do you think tubes need "100vac"? How would that work?

author: jwflammia
author_rank: Newbie
timestamp: May 07, 2016, 02:38:08 pm
content: I don't think you understand what a tube is and how it works. Do a little research and get back to me.

author: botcrusher
author_rank: Regular Contributor
timestamp: May 07, 2016, 02:53:18 pm
content: While I'm not an expert in tubes, tbis doesn't seem unreasonable to me.QuoteThat's just from a wikipedia page.From other things I'm reading, this tube doesn't need a large amount of power, sure, the pi doesn't have a rail with the correct voltage. But the tube only needs about 1.89 Watts to operate the heater. I'd imagine that there is a cute little boost converter ready to get the appropriate voltage.I'm a bit weary at the price. The tube in question can be found for $15-20, those other components don't cost terribly much. But It is far from unreasonable.

author: suicidaleggroll
author_rank: Super Contributor
timestamp: May 07, 2016, 03:00:29 pm
content: Quote from: botcrusher on May 07, 2016, 02:53:18 pmAccording to the kickstarter page for the project (linked from the article) the amp has its own external 24V supply (which it then drops to 5V to feed the Pi as well).

author: jwflammia
author_rank: Newbie
timestamp: May 07, 2016, 03:23:24 pm
content: The 12au7 need 12.6v AC or DC at about .16 amps to turn on the heater and about 100 v DC (I said AC in an earlier post, a typo) plate voltage to work. The 24v power supply will light up the tube and it will look pretty but will have little or no effect to the circuit.

author: IanJ
author_rank: Unknown
timestamp: May 07, 2016, 03:32:05 pm
content: Tubes do not necessarily need high plate voltages..........it's called tube starving. There are a few guitar foot pedals that have tubes in them with no sign of high DC voltages. Whether they sound the same is up for debate.........Ian.

author: krivx
author_rank: Frequent Contributor
timestamp: May 07, 2016, 04:24:04 pm
content: Quote from: jwflammia on May 07, 2016, 03:23:24 pmThey will operate as triodes just fine at plate voltages well below 100V, as long as the heater is working. The 12au7 datasheet specifies the plate characteristic well below 100Vhttp://www.sophiaelectric.com/pages/se/12au7.pdf

author: Fungus
author_rank: Super Contributor
timestamp: May 07, 2016, 05:11:11 pm
content: Quote from: stmdude on May 07, 2016, 01:11:08 pmI think that:a) People who like that sort of distortion probably already have it,b) Putting an amplifier that close to a digital circuit will probably end badly.Seems to me more like a geeky conversation piece than a useful amplifier.

author: StillTrying
author_rank: Super Contributor
timestamp: May 07, 2016, 10:42:50 pm
content: If they lit the tube by an orange led beneath it, and did the distortion another way, how many would notice?

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: May 07, 2016, 10:49:50 pm
content: Quote from: jwflammia on May 07, 2016, 02:38:08 pmRight back at ya, chief.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: May 07, 2016, 10:53:13 pm
content: Quote from: blueskull on May 07, 2016, 04:27:22 pmAccording to an expert with 5 posts, the problem is "you [don't] understand what a tube is and how it works. "Interesting. I wonder if he will school me on how Nuvistors work, or maybe pencil triodes? I'd be ever so grateful to have the operation of the 2GHz tube-based LO explained to me from a person who can't tell ac from dc.Or maybe he can explain 1940s hearing-aid tubes to me?

author: Delta
author_rank: Super Contributor
timestamp: May 08, 2016, 12:15:52 am
content: I see no audiophoolery here, just a quirky little product for those who like "dat kind of ting" (said in an Irish accent, so some reason...)Valvesdosound different to transistors, they add more (and different) harmonic distortion than transistors. Some people like what they do to the audio signal, hey Ilovewhat they do to the signal from my Telecaster!Audiophoolery comes into it when idiots claim their £££££££ valve amp "performs" (subjective term) better than a ££ solid state amp because it produces less distortion or suchlike, which is objectively bollocks.

author: dannyf
author_rank: Super Contributor
timestamp: May 08, 2016, 01:28:50 am
content: QuoteQuite frankly, I don't understand the phoolery that some people seem to be so single-mindedly focused on exposing such "phoolery". itself is pretty phoolery if you ask me,QuoteVery good advice. You sound like could benefit greatly from it as well.