The exact Norton-Thevenin mathematical theory tells us that, WITH A FLAT IMPEDANCE LOAD, voltage and current devices get to the same place. So my interest these days is getting a flat impedance!
That seems a wise starting point Steve.
I bet that old Radford would sound wonderful with some upgrades.
I've always liked Rotel for the amazing build quality. These babies go on for decades! Occasional magic spray on the switches and they just go on and on.
I used to have a higher quality setup that spanned many stacked boxes, but really what's not to like in the simpler system?
I fiddled with the Class AB crossover bias which had wandered over the years thanks to a competent service manual. It was worth doing.
These things are built around differential amplifiers at heart. And the NE5532AN opamp was about as good as it got. Back in the day, people like Quad used class A circuits on preamps, but whatever. As it goes, there are good theoretical grounds for matching resistors around a differential amp which reduces noise from the earth rail known as common-mode. The more complex balanced line 3 opamp version version was what I was doing with a phono-preamp which I showed to Michael Creek.
In theory with low source impedance it shouldn't matter. But in practice most low level sources have an output impedance around 1K to protect them from short-circuit condition.
You will see the long-tailed pair in most amps these days, in some form.
I used to have a higher quality setup that spanned many stacked boxes, but really what's not to like in the simpler system?
I fiddled with the Class AB crossover bias which had wandered over the years thanks to a competent service manual. It was worth doing.
These things are built around differential amplifiers at heart. And the NE5532AN opamp was about as good as it got. Back in the day, people like Quad used class A circuits on preamps, but whatever. As it goes, there are good theoretical grounds for matching resistors around a differential amp which reduces noise from the earth rail known as common-mode. The more complex balanced line 3 opamp version version was what I was doing with a phono-preamp which I showed to Michael Creek.
In theory with low source impedance it shouldn't matter. But in practice most low level sources have an output impedance around 1K to protect them from short-circuit condition.
You will see the long-tailed pair in most amps these days, in some form.
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It's all good stuff, isn't it? Possibly one last thing to mention about Rotel is some of their sought after old CDs used the famous original Phillips and Sony ladder DACs. This is a technology that was never exceeded IMO.
There's a lot to like in MTM. It's a sound I like. It has presence and projection and annoys the neighbours less. An MT is a horror if you get too close to it. Because it's inverse square loudness and will deafen you.
I have never had anybody agree with me that MTTM might be an even better way to do things. Wall-mounted preferably.
Or a ribbon tweeter which does much the same thing. It's all about the dispersion. Joe D'Appolito designed MTM as a BW3 system. He was attempting to cure the lobing issue that BW3 has. And we know that you can get impedance very flat with butterworth.
I get quite cross when people bang on about combing. Within 30 degrees on axis, BW3 sounds fine. Further than that, it sounds no worse than the falloff from any phase-aligned system. My brother-in-law and I decided that in the sweet spot, twin speakers like this work very well. In a wide sense, we decided that 5.1 home cinema style was better for everybody in the room.
There's a lot to like in MTM. It's a sound I like. It has presence and projection and annoys the neighbours less. An MT is a horror if you get too close to it. Because it's inverse square loudness and will deafen you.
I have never had anybody agree with me that MTTM might be an even better way to do things. Wall-mounted preferably.
Or a ribbon tweeter which does much the same thing. It's all about the dispersion. Joe D'Appolito designed MTM as a BW3 system. He was attempting to cure the lobing issue that BW3 has. And we know that you can get impedance very flat with butterworth.
I get quite cross when people bang on about combing. Within 30 degrees on axis, BW3 sounds fine. Further than that, it sounds no worse than the falloff from any phase-aligned system. My brother-in-law and I decided that in the sweet spot, twin speakers like this work very well. In a wide sense, we decided that 5.1 home cinema style was better for everybody in the room.
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The whizzer appears to work very well, hf dispersion is impressive, making the speaker effective over a very wide range of listening angles. In fact I sometimes listened to them side-on without any real problems in practice, perhaps the room fills in any issues. I detect something amiss dead on axis, but that dissappears a few degrees off. Bottom line - no beamimg.
Open backed box is going to have some dips and peaks like an open baffle but I didn't find it necessary to fx it. With the back on, the bass is more uniform sounding, but not quite as open so you takes your choice.
I don't recommend them for high power, they're not disco speakers.
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Yes, MTM's done well are able to play some magic (tricks).
The Living Voice MTM's are loved by many, though basically it's nothing more than a upgraded old Dali 104 (which my brother owns).
This should be that Rotel CDP, which is similar to (or based on) a Philips CD473 and/or CD650 if my memory serves me well.
The Living Voice MTM's are loved by many, though basically it's nothing more than a upgraded old Dali 104 (which my brother owns).
This should be that Rotel CDP, which is similar to (or based on) a Philips CD473 and/or CD650 if my memory serves me well.
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There's so many ways to skin a cat with loudspeakers.
TBH, I scarcely have time to build all the variations. Certainly, ShaneF warmed my heart with what started out as a simple attempt to build a competent computer speaker.
It ended up, IMO, as a near-perfect speaker for his small room using 5" SEAS CA15RLY drivers:
Seas CA15RLY X2 cabinet volume suggestions
TBH, he suffered from some mission creep adding a subwoofer. But really, I just didn't think he'd go far wrong in following a Steen Duelund idea. The Gryphon Mojo which goes for megabucks.
TBH, I scarcely have time to build all the variations. Certainly, ShaneF warmed my heart with what started out as a simple attempt to build a competent computer speaker.
It ended up, IMO, as a near-perfect speaker for his small room using 5" SEAS CA15RLY drivers:
Seas CA15RLY X2 cabinet volume suggestions
TBH, he suffered from some mission creep adding a subwoofer. But really, I just didn't think he'd go far wrong in following a Steen Duelund idea. The Gryphon Mojo which goes for megabucks.
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To conclude the Rotel R2R CDP's, here's an illustrative comment:
"FWIW, the biggest mistake I've ever made in this hobby was going from my beloved Rotel RCD855 (16 bit R2R) to a Rotel RCD 965 (bitstream) CD player during the end of my student days in the early 1990s. The loss in SQ was obvious in the first few notes. Fortunately, I rectified things by buying a Rotel RHCD-10 (20 bit R2R) a few years later, once I was finally working and earning some cash. I sold the RHCD-10 only a few years ago as I simply had no use for a CD player anymore. But to this day, I still maintain that the RHCD-10 is the best CD player I've ever heard - better than the Esoteric P70/D70 combo I had for many years, and better than the top-of-the-line Linn and Naim CD players I demoed at various dealers' places."
"FWIW, the biggest mistake I've ever made in this hobby was going from my beloved Rotel RCD855 (16 bit R2R) to a Rotel RCD 965 (bitstream) CD player during the end of my student days in the early 1990s. The loss in SQ was obvious in the first few notes. Fortunately, I rectified things by buying a Rotel RHCD-10 (20 bit R2R) a few years later, once I was finally working and earning some cash. I sold the RHCD-10 only a few years ago as I simply had no use for a CD player anymore. But to this day, I still maintain that the RHCD-10 is the best CD player I've ever heard - better than the Esoteric P70/D70 combo I had for many years, and better than the top-of-the-line Linn and Naim CD players I demoed at various dealers' places."
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TBH, My Rotel RCD-965BX (Limited Edition!) Bitstream CD player is a very ropey component.
Which is a shame because I shelled out over £300 for it. There's an unpleasant harshness at the top end. I really can't be bothered to wade through the schematic looking for weak links. Back in the day I'd replace electrolytic audio decoupling capacitors for MKT types and the like. Or use a better sigma-delta DAC.
But really, a competent CD mechanism for your computer costs about £15, and you could find a sound card with a good DAC quite cheaply. And wire it to your amp. Or just use the digital output of an old CD into something better DAC-wise. After all, the digital output should just be ones and zeroes and exact.
But we are speaker nuts! The most critical component IMO. Let's reiterate that little 5" plus 3/4" MA7 BW3 speaker I currently enjoy:
I'm actually amazed at the good bass sound a 5" can produce in 12L reflex. And VERY detailed.
There's a lot wrong with this speaker. But it does a lot right too. So, as a speaker nut, I want to keep the good things, and lose the bad things. This is the hobby, isn't it?
Which is a shame because I shelled out over £300 for it. There's an unpleasant harshness at the top end. I really can't be bothered to wade through the schematic looking for weak links. Back in the day I'd replace electrolytic audio decoupling capacitors for MKT types and the like. Or use a better sigma-delta DAC.
But really, a competent CD mechanism for your computer costs about £15, and you could find a sound card with a good DAC quite cheaply. And wire it to your amp. Or just use the digital output of an old CD into something better DAC-wise. After all, the digital output should just be ones and zeroes and exact.
But we are speaker nuts! The most critical component IMO. Let's reiterate that little 5" plus 3/4" MA7 BW3 speaker I currently enjoy:
I'm actually amazed at the good bass sound a 5" can produce in 12L reflex. And VERY detailed.
There's a lot wrong with this speaker. But it does a lot right too. So, as a speaker nut, I want to keep the good things, and lose the bad things. This is the hobby, isn't it?
HaHa. Certainly not a "little girl with a guitar" speaker so beloved of the simple crossover brigade! I'm currently "Groovin with Mr. Blow", aka Mr. Miles Davis on "Kind of Blue". The best way to explain Jazz, is you just set off not quite knowing where you are going to arrive.
According to my best simulation, this little butterworth3 MA7 has TERRIBLE impedance, and a peaky nature that may be slightly ameliorated by NP capacitors:
Some of Miles' notes just shriek. But overall a very good sound. So I think we should MTM this idea at ear-height. And since that ends up a bit tower, we might as well add a bigger 8" woofer and go 3-way.
I really don't know about tweeters. Surprisingly, classic old mylar plastic types seem to work well.
It's is all very Wharfedale E70, which had series wired mids:
But we can do a better job on crossover and the flat impedance. We now know how to do that.
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For small scale / small rooms / nearfield, 5 or 5.5" modern woofers - aspecially low Fs linear quality drivers from ScanSpeak, SEAS and similar - will cover 30 something up to 4-5000Hz. I have some Totem speakers with 5.5" SS and there's no sub needed with these.
Still: a large, light cone covering roughly 30-1000Hz is another universe, provided you have some space to let them breathe.
Still: a large, light cone covering roughly 30-1000Hz is another universe, provided you have some space to let them breathe.
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Here's a website I really like. This is a guy called Louis Coraggio, now sadly deceased. And his take on the easy 5" Scanspeak plus 1" Hiquphon idea:
HiquiSpeak 2 Way Monitor
I think he missed a trick on the low-dipping impedance, which would be fixed with your more classic BW3 3.3uF/0.3mH/10uF tweeter filter. And 12-15L reflex seems a no-brainer to me.
What I liked about Lou, is he is very honest that he just did it for fun and yuks. He also liked cheap most of the time.
I'm working through my heap of speakers right now.
TBH, I thought I'd finished this one. But the 3/4" SEAS 19TAF/G metal dome top-end really isn't as nice as the 3/4" mylar dome in the MA7 on Miles Davis and his band.
The cone Visaton TW70 is so small it won't fit. I think I shall go back to the Monacor HT22-8 cone tweeter. Something very musical and present about that one. Marco_gea wisely said one of it's strengths is the dispersion discontinuity at (3.5kHz and negative polarity) crossover is less abrupt than with small domes.
You Americans have a few freely available cone tweeters too, even ferrofluid:
100+ Tweeters in stock from Vifa, Dayton Audio, Aurum Cantus, Goldwood, Beston, and other High Quality Tweeter brands.
HiquiSpeak 2 Way Monitor
I think he missed a trick on the low-dipping impedance, which would be fixed with your more classic BW3 3.3uF/0.3mH/10uF tweeter filter. And 12-15L reflex seems a no-brainer to me.
What I liked about Lou, is he is very honest that he just did it for fun and yuks. He also liked cheap most of the time.
I'm working through my heap of speakers right now.
TBH, I thought I'd finished this one. But the 3/4" SEAS 19TAF/G metal dome top-end really isn't as nice as the 3/4" mylar dome in the MA7 on Miles Davis and his band.
The cone Visaton TW70 is so small it won't fit. I think I shall go back to the Monacor HT22-8 cone tweeter. Something very musical and present about that one. Marco_gea wisely said one of it's strengths is the dispersion discontinuity at (3.5kHz and negative polarity) crossover is less abrupt than with small domes.
You Americans have a few freely available cone tweeters too, even ferrofluid:
100+ Tweeters in stock from Vifa, Dayton Audio, Aurum Cantus, Goldwood, Beston, and other High Quality Tweeter brands.
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