--------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: EAZ00001 Date: 06/29/97 From: KEITH KNAPP Time: 09:26pm \/To: BONNIE GOODWIN (Read 0 times) Subj: Re: Website for AUDIO BG> I think we both agree that tubes are highly ineffecient, and rediculous BG>to use in digital audio.. That tubes were used in early computers is in BG>itself quite funny by today's standards. Whether tubes are highly inefficient (they are) does not relate to whether or not they sound good. I remember the first CD players -- the sound was pathetic. There was a weird veil of noise between the speakers and the viewer, and a feeling of fingers dragging on a slate chalkboard. Since then, CD audio has certainly gotten better, but the output is still a series of tiny square waves, the phase of which has little to do with the original high-frequency waves they were spoze to record. In every way _except_ those, I think digital is way cool, and clearly the wave of the future. Perhaps the more enlightened among us analog curmudgeons are not hankering for the past, but merely for a digital future that doesn't sound synthetic or irritating. Oddly enough, if I were an audio professional and had to buy hardware, I'd probably buy digital for cost reasons. But I'd still put a 12AX7 on the monitor outs. So there. Nyah nyah! * SLMR 2.1a * . Wisdom consists in knowing when to avoid perfection. --- PCBoard (R) v15.3/5 * Origin: * Binary illusions BBS * Albuquerque, NM * 505.897.8282 * (1:301/45) --------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: EAZ00002 Date: 06/30/97 From: PHIL ROBERTS Time: 01:55am \/To: DON DELLMANN (Read 0 times) Subj: Swapping Turntables -=[ Quoting Don Dellmann to Phil Roberts ]=- PR> Automatic is a must, as people from the steel-needle generation are PR> really hard on the stylus and don't use the cueing lever! I think I PR> have a lead on an old Garrard that's barely been used...which would be PR> a great table for this system and is convertable between single-play PR> and stack by changing the spindle. DD> Sounds like my "daily drivers" a pair of Garrard SL-95b's (plus three DD> more in the basement for "parts" to keep 'em running.) DD> I pick up that model whenever I see one at a rummage sale just to DD> insure a supply of parts, since the SL-95b was probably one of the last DD> "affordable" units made that would still handle 78's (which comprise DD> about 8% of my collection). I'm still hunting for the table. Turns out the one I knew was in Mom's attic and almost never used, well it's a victim of time and Mom's attic. All the rubber parts are shot, even the turntable mat has developed a bad dry rot! I can deal with friction tires, but finding a turntable mat that looks right doesn't sound like an easy task. BTW, I think that was the SL-95b. Definitely a Synchro-Lab. Phil --- Bink/Max/GE 1.20 Pro * Origin: Analytical Engine CBCS * 28.8k BPS * [216] 942-3876 (1:157/554) --------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: EAZ00003 Date: 06/29/97 From: TERRY SMITH Time: 11:11pm \/To: DAVID SCHMOLL (Read 0 times) Subj: system balancing DS> Actually what I described was from a booklet from Apogee called sound DS> reinforcement for worship, written by the Director of education and DS> senior systems engineer of Apogee, Patrick Price. In other words, some oversimplified sales literature to comfort people trying to have incompetent volunteers pretend to be able to handle things they should contract out.... DS> The point you should be concerned with is that if you use an assortment DS> of power amps in your system, and your high frequencies are amplified DS> by a factor of 40X, your mids are amplified by a factor of 45X, and DS> your lows are amplified by a factor of 35X, The high/mid/low balance DS> through the speakers will be severely messed up. Some parts of what you quoted aren't too far off as simple explanations. The above seems to be the heart of the instructions, and is quite simply wrong. DS> To properly calibrate a sytem using amps with different gains you must DS> use the gain controls on the amps to match their output levels (given DS> the same input) to that of the amp(s) with the lowest specified gain. DS> Start by putting a 0.5 volt 1kHz sine wave signal into each amp (no DS> speakers connected), and use an AC volt meter to measure the output DS> Now go through the remaining amps once again using the same 0.5 volt DS> input signal and adjust their gain controls so that the output voltage DS> matches that of the reference amp. DS> I attempted to say the same thing in less words in my original post, so DS> the question remains is the above valid or hype? I can't see how not DS> including the speaker efficiencies in the overall balance makes sense. You're right; it's hype. Bonnie's summary here was much more realistic. What they suggest, though leaving speakers connected, could be valid for full range cabinets closely located or covering different areas with similar system gain needs, and with similar cabinet ratings. Those are unrealistic assumptions. The implied 3 way system makes that idea utterly absurd. It is interesting to note that they likely suggest tests with speakers disconnected to avoid being blamed for destroying garbage better taken direct to the dumpster as found in many churches, while suggesting a procedure ripe for toasting mid/high compression drivers. It's also interesting to note how they fail to mention what would happen if you feed their 1 KHz tone to the amps via an electronic crossover. Dare I mention architectural acoustics, and differences between music fidelity and speech intelligibility? Terry --- Maximus 2.01wb * Origin: Do it near resonance! (203)732-0575 (1:141/1275) --------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: EAZ00004 Date: 06/29/97 From: TERRY SMITH Time: 11:26pm \/To: BONNIE GOODWIN (Read 0 times) Subj: Most common cassette tape type 23:26:0606/29/97 BG> Wonderful message about tape formulations, an area that I'm not that BG> versed on since I do as little with cassette as possible and that will I've done a lot less analog tape recorder setup work in recent years than I used to too. BG> shortly be even more so. I was unaware of that distortion in the Chrome With a mid frequency tone near SOL it's typically about 0.7 or 1.0 for ferric, versus about 1.0 or 1.4 for chrome and similar quality pairings of each tape type from various vendors and alignment choices. As you likely know better than most here, there are a number of compromises reflecting alignment choices, hardware, and oxide that complicate precise answers. BG> settings. Does the ferrite formulations emulating the Chrome also have I hesitate to offer a blanket answer, as I suspect exceptions exist and manufacturers change formulations periodically such that one would have to be an engineering supervisor at Ampex or a similar competitor for some time to have really solid wide scale data. Some such formulations seem to have that trait based on my experience. (I won't call it a "problem" since both analog and digital media have trade offs by design.) I'd hope any really serious tape users would test specific hardware, media, and alignment setups in house, in order to make informed choices to limit the scope of what's used, as opposed to more wild assed assumptions common to less serious users. BG> this problem? Also, as you know, tape has a natively high distortion BG> anyway. That's a feature, not a bug. Could you have imagined 48 tracks of tube limiters years ago, or FX boxes to give choices of odd/even harmonic simulations? Of course we've both spotted production glitches of unintended tape saturation on music releases over the years, as well as some intentional use of hot or conservative levels. Terry --- Maximus 2.01wb * Origin: Do it near resonance! (203)732-0575 (1:141/1275) --------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: EAZ00005 Date: 06/29/97 From: TERRY SMITH Time: 11:42pm \/To: BONNIE GOODWIN (Read 0 times) Subj: system balancing -> creative designs, have you ever had the chance to play with one of -> those theater/auditorium reinforcement systems designed to prevent -> regenerative feedback by using 100 plus drivers staggered around the -> audience, and computer switching which drivers are active quickly -> enough so that any given feedback path based on phasing and room -> quirks never has time to develop after space delays are included? BG> No I haven't Terry, and until now hadn't considered just what would be BG> needed to make such a system work correctly.. One thing that I would Budget to customize the algorithm to the acoustic environment? BG> love to play with sometimes is phase adjustments on BG> individual speakers within an array for feedback supression, coverage BG> pattern shaping, etc.. Acoustic theory in that respect really isn't much different than the RF work I do with directional arrays, other than a screwier set of wavelength to bandwidth relationships and lots of assymetrical non-point source sources. Cheap quality delay lines should make that practical for the better touring sound companies. BG> I've played some with the early Sabine feedback suppression, but that is BG> trying to find the offending frequencies and stomping on them hard.. The BG> enough filters to remove all of the offending frequencies with narrow BG> notch filters, or you get a frequency response that is riddled with BG> narrow holes in it, kind of like a field after a artillery shelling. BG> This is also a compromise point with this system of EQing. Enter noise cancelling mic systems. How about pairs of B&K small diaphragm omnis that offer near point source laboratory uniformity performance? Of course, they only work on very close mic'ing, with trained users. At least cheap wireless in the ear monitors have helped a lot. Since this isn't the "pro-" echo, should we let the mundane folk consider that monitors usually feed back before mains? BG> Another technique that can be used in a non musical situation is doing BG> pitch shifting the sound before hitting the amplifiers just a tad. That BG> confuses the feedback a little. I much prefer the old school trick of inserting roughly one syllable of delay. That does wonders testing the concentration abilities of professors. I'd hate to try that on a public speaker trained as a pipe organist though. As to more serious applications, it could be interesting to try scrambling circuits as have been used to randomize positive and negative polarity audio assymetry to equalize modulation in broadcast FM limiters as a minor feedback threshhold improvement trick. BG> Perhaps to me, the most important consideration in getting system BG> feedback down is NOM, or Number of Open Mics, which directly effects BG> system feeedback "headroom". We are much too microphone happy now... BG> Sound consoles now have more inputs than most recording mixdown systems BG> need with an arsonel of microphones that often makes the studios BG> envious. Keep that NOM as low as you can at all times. Ever work with automatic mic mixers? I've installed JBL's of a couple of eras in broadcast talk studios and churches alike. In live situations the simple reduction in space phasing problems can increase speech index surprisingly. In recording I'd imagine they could work better in some cases than typical channel gates, especially when you consider how room acoustics and background noise change character with different numbers of mics, or too many shut off compared to average open mics. We agree on the importance of NOM. I disagree that consoles with reasonably cheap capacity cause foolish operation though. Silly human technical incompetency and hype driven business might better get that credit. Terry --- Maximus 2.01wb * Origin: Do it near resonance! (203)732-0575 (1:141/1275) --------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: EAZ00006 Date: 06/28/97 From: THOM KOUWENHOVEN Time: 04:19pm \/To: TERRY SMITH (Read 0 times) Subj: system balancing Hi there Terry Op 26 Jun 97 21:29 you wrote something about *system balancing*... TS> I'd like to be able to generate 10+ KW of acoustic energy (NOT amp power TS> ) from 8 Hz through 5 KHz, tapering down to 1 KW of acoustic energy t TS> 25 KHz, within an area the size of a 500 person hall. Are you into audio or into assassination ? ;) Greetingzetcetera, Thom *----* ... Never let yesterday or tomorrow use up today. --- GEcho 1.00 * Origin: Aargh! BBS Amsterdam (31-20-6732585) (2:280/606.19) --------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: EAZ00007 Date: 06/29/97 From: THOM KOUWENHOVEN Time: 09:13pm \/To: DAVID SCHMOLL (Read 0 times) Subj: system balancing Goeiemorgen DAVID Op 27 Jun 97 08:23 had jij het over *system balancing*... DS> I attempted to say the same thing in less words in my original post, so DS> the question remains is the above valid or hype? I can't see how not DS> including the speaker efficiencies in the overall balance makes sense. You're right...it doesn't :) Groetenzenzovoorts, Thom *----* ... Een brok in de keel krijgen. --- GEcho 1.00 * Origin: Aargh! BBS Amsterdam (31-20-6732585) (2:280/606.19) --------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: EB100000 Date: 06/29/97 From: BONNIE GOODWIN Time: 07:35am \/To: JOHN ALLEN (Read 0 times) Subj: system balancing Hi John! -> Hi Terry, Your last ref'd: -> >>Giving summary impressions first, it sounds like you read some -> silly marketingBS, with some slightly confused suggestions that -> aren't quite right outsidebeing helpful simplified procedures within -> some possible context you didn'tdescribe as being detailed in what -> you read.<< -> After reading that about a dozen times I still haven't a clue if your -> talking about amps, military movements or a missing gobb of silly -> putty. HAHAHAHAHA!!! Not sure who was the funniest in that exchange, but both sure tickled my funny bone this AM!! Bonnie *:> --- QScan/PCB v1.18b / 01-0249 * Origin: The Capitol City Gateway, Since Dec 1979, 916-381-8788 (1:203/909) --------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: EB100001 Date: 06/29/97 From: BONNIE GOODWIN Time: 07:39am \/To: TERRY SMITH (Read 0 times) Subj: system balancing Hiya Terry! -> I'd like to be able to generate 10+ KW of acoustic energy (NOT amp -> power ) from 8 Hz through 5 KHz, tapering down to 1 KW of -> acoustic energy at 25 KHz, within an area the size of a 500 person -> hall. Care to try that goal, and more importantly, dare to venture -> in during an experiment in mind control through sound stimuli, -> audible and otherwise? <> -> I want this done efficiently, as you're limited to 1200 amps of 208 V -> 3 phase, including lower power incidental equipment for the hall. -> ;-) But you haven't stated whether you want to just chop or puree the audience... maybe just make a cannibal soup? Bonnie *:> --- QScan/PCB v1.18b / 01-0249 * Origin: The Capitol City Gateway, Since Dec 1979, 916-381-8788 (1:203/909) --------------- FIDO MESSAGE AREA==> TOPIC: 183 AUDIO Ref: EB100002 Date: 06/30/97 From: CAMERON HALL Time: 10:41am \/To: ALL (Read 0 times) Subj: Re: Most common cassette tape type -=> Quoting Bonnie Goodwin to Terry Smith <=- BG> Wonderful message about tape formulations, an area that I'm not that BG> versed on since I do as little with cassette as possible and that will BG> shortly be even more so. I was unaware of that distortion in the BG> Chrome settings. Does the ferrite formulations emulating the Chrome My experience with the various formulations sorta goes like this: :) Type I (normal): Slightly higher noise floor, higher high frequency distortion. Top of the line tapes are very good however. Type II (true CrO2): Low noise. Record EQ requirements slightly different than "fake" CrO2 formulations. Very clean, but high frequencies saturate at a somewhat lower level, but do it without much distortion. Type II (Chrome Equivalent): Mostly excellent overall performance with slightly higher noise floor then "true chrome". Type II (Metal particle): Excellent performance overall. EQ requirements for recording can produce a real "zip" at the top end if the machine is set up for "true chrome". Type III (Ferro-chrome): A hybrid of standard and "true chrome". Had very low noise. However, the wild differences between brands for record bias/EQ requirements and advances in Type II equivalents made this formulation obsolete. Overall sound was fine with the "true chrome" high frequency saturation effects but a cleaner low end performance. Type IV (Metal): Excellent top notch performance. Early runs of equipment couldn't properly utilize this tape as manufactures were still learning how to deal with it. And some were deceptive in claiming "metal" compatibility but the recording head, recording circuitry, bias generator etc. actually couldn't cope. These were soon weeded out. Some other random comments. A deck with Dolby HX-Pro with normal tape and Dolby C can provide very good performance if a higher end type I is used. After several decks over the years, I've finally settled on an AIWA ADF-990, which I got in the early '80's if I remember correctly. It's still working well but starting to show it's age with slightly higher flutter. Having obtained the service manual, I was able to fine-tune the auto-adjust and with a metal tape and Dolby C, it's hard to tell tape from source (it's a 3 head deck). I don't do hardly any taping now, as we've gone to a Panasonic cd portable. :-) And, yes, buying re-issues often makes a profound improvement in the quality of CD sound. BG> also have this problem? Also, as you know, tape has a natively high BG> distortion anyway. Absolutely! Experience though shows that for those who tape for the car, the "true chrome" types with the falling top end can sound very pleasing in the auto car units, softening some of the brutal top end on many CD's. Knowing what brand produces what type of recorded effect can often enhance the final outcome. Cameron Hall cameron.hall@bluebeam.gryn.org | ad121@hwcn.org Blue Beam MailServer | 905 662 5784 | Stoney Creek ON Canada | v34 FAX --- GEcho 1.00 * Origin: Blue Beam MailServer Stoney Creek Canada (1:2424/3120)