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Old 21st April 2012, 11:48 PM   #4611
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Quote:
Originally Posted by a.wayne View Post
TVR,

Small speakers lack percussive energy, of course small room , small speaker, there is no way around that, speaker to room ratio has to be optimized for proper reproduction ...
Happy we agree on that. The trick is to get the speaker to room ratio as low as you can get without compromizing sound quality.
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Old 22nd April 2012, 01:08 AM   #4612
a.wayne is offline a.wayne  United States
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Tvr ,

My spenglish must be bad ....

IM NOT IN FAVOR OF SMALL DRIVERS, small systems or small amplifiers and don't get me started on FR single driver systems ...

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Old 22nd April 2012, 04:22 AM   #4613
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Hi,

Quote:
Originally Posted by jcx View Post
where did my post say anything about THD?
Okay, you did not say HD, however, the result invariably is low THD with extended high order harmonics.

All the various distortion mechanisms in Amplifiers tend to increase with rising frequency. Open loop gain tends to fall with rising frequency. So distortion rises with frequency often quite dramatically.

So it matters very little what happens where inherent (pre NFB) distortion is low and where loop gain is high, especially if you have sources with some ultrasonic signal content or noise (LP, Reel2Reel, SACD, Non-OS DAC's, > 48KHz sample rate PCM).

Using multiple distorting stages in series will create additional high order products not present in individual stages distortion. Using "local" methods (degeneration, cascoding etc.) will linearise individual stages so we do not get as much "distortion of distortion". Maximising the input stage linearity reduces "re-entrant distortion".

All this means relatively low levels of looped NFB with a very wide bandwidth. However if care is taken low enough HD can be attained this way.

Ciao T
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Old 22nd April 2012, 04:35 AM   #4614
Previously: Kuei Yang Wang
 
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Hi,

Quote:
Originally Posted by tvrgeek View Post
OK A, just where does one get a full range driver?
That depends on your definition of "full range driver". If you define Full Range as 20Hz-20KHz +/-1dB there is no such thing and there is also no such multi-way speaker, if we do not apply massive averaging.

However it is possible for example, to make a driver that can handle 40Hz - 16KHz in a 40 Liter vented enclosure, with a reasonably flat response to qualify for use as Studio Monitor in smaller rooms and at civilised levels.

In this case we are talking about the East German Z131/L40 Monitor which used the Schulze KSP-215 8" Fullrange Driver, rated at 12.5VA continuous power, introduced in 1966 and still in wide service in East Germany in 1989...

Ciao T
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Old 22nd April 2012, 06:27 AM   #4615
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I remember bi-amped BEAG studeo monitors, size of refrigerator, they were gorgeous devices!

Click the image to open in full size.
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Old 22nd April 2012, 06:59 AM   #4616
Previously: Kuei Yang Wang
 
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Hi,

Quote:
Originally Posted by Wavebourn View Post
I remember bi-amped BEAG studeo monitors, size of refrigerator, they were gorgeous devices!

Click the image to open in full size.
These look like influenced by the Telefunken O85. Old Mono Systems with very wide dispersion. With Stereo transmissions they had to be replaced.

The L40 looked rather more pedestrian. If matched with an Amplifier (original EL84 push-Pull, later transistorised) that equalised the response (instead of the Passive EQ in the Box) it became the Z132 Monitor System...

Click the image to open in full size.

There where many versions using this full range driver, from the 20 Liter sealed "Kugelboxen" K20 (spherical speakers of which some 60,000 where made and which hence still occasionally show up on e-bay) to the 80 Liter Reflex "L80".

More products from Heli in East Germany, both domestic and Studio may be found here:

www.HELIRADIO.de (Produkte)

Following the "Anschluss" in 1990 like many especially smaller companies in East Germany Heli was allowed the slow death of a thousand cuts, until it had to close.

About the only East German Studio/Pro Gear manufacturer that survived is justly famous MEG (Musikelektronik Geithain), oh yes, Vermona, maker of what I derived the "Zen-EQ"from also still cling on to life, in the day we used to call their gear "Zerrmona" (a wordgame substituting one of the german words for distortion into the company name)...

Ciao T
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Old 22nd April 2012, 07:09 AM   #4617
dvv is offline dvv  Serbia
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Thorsten, I must take issue with the idea that FM tuners have poor pilot tone (19 kHz) and subcarrier (38 kHz) rejection. That was a problem resolved even in the late 70ies.

Yes, some did have bad breakthrough, but we've moved a LONG way since then. But most had the problem more or less resolved. And I am not referring to my own reVox B760, rated at -70 dB out to 19...300 kHz (including all harmonics), that would be unreasonable given that its price made it very much a High End tuner in its day.

My Sony 3950 tuner did fairly well itself, rated at -50 dB 19 kHz and -70 dB 38 kHz. And that was no High End tuner, just areasonably good representative of its genre.

Ultimately, one could (and should!) question the logic of using a say DM 2,000 amp with a DM 300 tuner, which might have some problems.

The point being that I think MOST (but certainly not all) tuners would not be suspect in that arena.

SACD is another matter. Frankly, I know much less about it, I tried a few, even bought one (Denon 3910) of those "universal players", but the sofware came in greatly lacking, so eventually I gave it up as a moribund standard, a victim of MP3. A pity, I feel, but there it is. Anyway, again a sample or two could have problems with outgoing ultrasonic trash, which could upset the amp. But here again, one questions the logic of using a high quality amp with a cheap, run-off-the-mill Chinese made DVD/BD/SACD device.

That said, I still think reVox' logic is a good hint - make the amp capable of doing 300 kHz or better, and then install a first order filter at its input with a cutoff frequency of 200 kHz. It's simply a precaution well worth taking, that's all.

Brings into play the logic of a "tailored bandwidth", as not infrequently used in UK audio products. Quite simply, a high pass and a low pass second order filters, with cutoff frequencies of say 3 Hz and 80 kHz, usually executed with two op amps. Well, they used to do that, don't know how it goes these days.

Some of the DIY legends, such as Prof W. Marshall Leach's amps, used to have second order filters at their inputs, I forgot the cutoff frequency, but it was kinda low(ish). Just in case.
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Old 22nd April 2012, 07:20 AM   #4618
Previously: Kuei Yang Wang
 
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Hi,

Quote:
Originally Posted by dvv View Post
Thorsten, I must take issue with the idea that FM tuners have poor pilot tone (19 kHz) and subcarrier (38 kHz) rejection. That was a problem resolved even in the late 70ies.
When I was younger the Pilot Tone drove me nuts (like ringing in your ears), despite the Tuner being fitted with a Pilot tone Filter. I ended up building a 19KHz T-Network filter that added another 40dB or so and even fitted it to my Bathroom portable (mono) radio... Maybe I'm more sensitive than most.

The Revox should do okay.

Ciao T
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Old 22nd April 2012, 07:33 AM   #4619
dvv is offline dvv  Serbia
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Wayne,

You are wasting your time knocking on an open wide door, arguing that small speakers lack the wherewithall for a lifelike sound, at least in my case.

Historically, I got over that problem in 1972, when I exchanged a pair of small Uher speakers, which my dad purchased with their Royal de Luxe tape recorder (with built-in amps 2x10Wrms), for a pair of AR5 speakers. I'd have to be stone deaf not to notice the difference.

Ever since then, I have owned nothing but larger speakers, and I never once looked back.

As a general rule, small speakers image better than most big speakers, they tend to portray a wider sound stage, but dismally fall on drive impetus and sheer size presentation. Balls of glass, you might say.

I prefer balls of brass, even if I do pay for it for a little less imaging. Remember, I used to bang on the drums in my time, and anything that fails to do drums properly hasn't got a chance in hell with me. This assumes a bass driver no smaller than 10 inches (26 cm), and it has to be a 3 way speaker, because by the time one graduates to 3 way, one is able to optimize each driver for its near optimum reproduction range (assuming a good initial choice of drivers).

But let also say this - if you want to play the power game, then you have in all probability lost it before you even started unless you opt for well made (not just any, ol' ...) pair of active speakers. Consider - active speakers do not use passive crossovers, which rob you of a lot of input power. If their own built-in amps are well judged, the sheer feeling of a bottomless pit of power will be there, that subjective feeling that it has limitless power on tap - a trait I treasure greatly in all instances.

And, in addition, you can actually optimize your power amps for a specific driver. You do NOT need, under any cirumstances, more that say 50 Watts for a midrange driver, unless it is uncommonly inefficient, and your tweeter doesn't need more than say 30 Wrms - but these could well be pure class A watts, and NOTHING beats that.

Trust me on this, I have heard active sšpeakers from Philips, Grundig, Klen & Hummel (we had them in the studio of the TV editing room), ATC and several other less well known makers. And in all cases, the sheer dynamic range of them left like 90% of classic passive speakers standing still, even when driven by real high class amplification, which invariably ran your bill way higher than when using active right from bat.

Small monitors, even active ones, make sense only in ENG vehicles, where space is at a premium. Hence models like the BBC LS monitors, all the rage in the UK in the 70ies. Nice speakers, but they managed to lose bass altogether, they simply had none. That might be acceptable in an ENG vehicle, but certainly not im my room. I want and need the slam of it, and I'm not going to get any real slam with a 6.5 inch "bass/mid" driver.

And it generally works the other way as well - sticking in a 12 inch (30 cm) bass driver into as small a box as you can make it is not going to give that driver much of a chance. The only excpetion to this rule that I know of are some (not all) models made by a German company called Canton, such as model 530 and so forth - they had 12 inch drivers in smallish boxes which still somehow managed very decent bass (these were acoustic suspension models). They don't go below around 50 Hz, but what they do, they do well.
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Old 22nd April 2012, 07:43 AM   #4620
dvv is offline dvv  Serbia
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Quote:
Originally Posted by ThorstenL View Post
Hi,

When I was younger the Pilot Tone drove me nuts (like ringing in your ears), despite the Tuner being fitted with a Pilot tone Filter. I ended up building a 19KHz T-Network filter that added another 40dB or so and even fitted it to my Bathroom portable (mono) radio... Maybe I'm more sensitive than most.

The Revox should do okay.

Ciao T
Yeah, I know, that chirping sound, like you had birds inside the tuner. I've heard it on some occasions, and I believe you when you say it drove you nuts, it would drive me nuts too if I had to listen to it all day long.

My own situation was even more complicated. Being a city slicker, I also needed tuners which killed the pilot tone and subcarrier dead, but also did AM suppression well. Not easy to find, and not cheap either (at least in those days).

But again, the B760 does this uncommonly well, rated at -70 dB.

Actually, the REAL miracle here is that I still have 3 or 4 even FM stations which do NOT use PC driven MP3 for their programme, rather they stick to the true 16-bit CD format and pay attention to their sound quality. Not infrequently, you don't know whether you're listening to the tuner or the CD player, which is saying something.

But I suspect high compression DAB will end all that soon enough.
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