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 Post subject: The Perfect Speaker
PostPosted: Oct Thu 19, 2017 8:58 pm 
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Obviously, there can be no 'perfect' speaker for every application, but on the subject of vintage audio, specifically tube amps, what do you think would be the perfect speaker?

I am a devotee of the original mono '50's equipment, primarily Fisher, Bogen, Harmon Kardon, HH Scott, et al. So, for me, I would like something full range, high efficiency, with an easy impedance curve that tube amps will find easy to drive.

The speaker tends to be the weakest link in the audio chain, thus the most expensive. Currently I use a homebrew speaker that is about 8 cubic feet, with JBL 2226H woofer, B&C 6MD38 mid, a B&C DE250-8 tweeter with horn, and of course a homebrew crossover. I find it very satisfactory.

There are some vintage speakers I wouldn't mind having, like the klipsch cornerhorn or perhaps one of the big altecs, but modern music tends to work older speakers very hard at the extreme ends of the audio spectrum, so I would always be afraid of a failure, which would most likely be very expensive to replace, if not impossible, so there is that.

What do you think?


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 Post subject: Re: The Perfect Speaker
PostPosted: Oct Thu 19, 2017 9:36 pm 
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This may be on the low end of your list but I have a Warfedale W-60 and I find it very pleasing to listen to with both Jazz and Classical.


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 Post subject: Re: The Perfect Speaker
PostPosted: Oct Fri 20, 2017 3:17 am 
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wharfedale W70 speakers are absolutely fantastic on good tube hi fi equip.

steve

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 Post subject: Re: The Perfect Speaker
PostPosted: Oct Fri 20, 2017 1:21 pm 
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My preference would be an old Bozak speaker. I have several of them and I really like them with tube equipment. Harry


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 Post subject: Re: The Perfect Speaker
PostPosted: Oct Fri 20, 2017 2:06 pm 
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"Perfect".......OK, please submit your financial data so we can assess how much you can afford.....;)

To an engineer, "perfect" is often read as "accurate". For a speaker, this means that the acoustic pressure has to match the input signal. The dominant issue is resonance. The ubiquitous conical speaker driven by an electromagnet is a spring-mass system with a natural frequency that is within the human hearing range. This "feature" has led to an abundance of effort in enclosure design and electronic design, some of which addresses another fundamental issue...to wit the sound that comes off the back of the cone.

Let's tackle the resonance first. To get the resonance out of our hearing range, there are two options:
Increase the mass, thereby putting the resonance below our hearing range.
Increase the stiffness, putting the resonance ABOVE our range.
Either one of these will require substantial power.

As for the "back wave", my impression is that the closed enclosure (acoustic suspension) is the most accurate, but I really have no current knowledge.

Bottom line: "perfect" will cost money and power. How much do you have?

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Last edited by pixellany on Oct Fri 20, 2017 6:36 pm, edited 1 time in total.

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 Post subject: Re: The Perfect Speaker
PostPosted: Oct Fri 20, 2017 6:13 pm 
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Speaker selection is highly personal. What sounds good to you may not sound good to someone else. What I always recommend is to go out and listen to as much un-amplified live music as you can, giving you a baseline as to what music should sound like that you can use to evaluate speakers.

Back in the day bass-reflex speakers were very popular due to high efficiency. They work well with tube amplifiers as they are well damped internally. However, to deliver very low bass they have to be large. Acoustic suspension speakers tend to be more accurate and are smaller but are inefficient as the back wave is used within the cabinet to create damping. Some of them work fine with tube amplifiers but others really depend on the high damping factor of a solid-state amplifier and will sound very tubby with a tube amplifier.

-David


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 Post subject: Re: The Perfect Speaker
PostPosted: Oct Fri 20, 2017 6:45 pm 
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and here we have a thread that will go down multiple side roads.....;)

I am curious about some things like electrostatic speakers. It seems like the perfect solution for the high end but, for low frequencies, the required travel would mean some pretty high voltages---or some other clever trick?

For the low-end, we see systems with multiple drivers. I wonder how far this can be carried---eg could one make a relatively small bass driver, and then put them in an array? Small cone but long travel--how would that work?

more hare-brain: Has anyone ever done a driver with no spring---this would use some kind of active position control, with a simple plate on the end of a piston. "no spring" is of course not possible, but could you get the spring constant low enough to push the resonance below human hearing?

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 Post subject: Re: The Perfect Speaker
PostPosted: Oct Sat 21, 2017 4:45 pm 
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pixellany wrote:
more hare-brain: Has anyone ever done a driver with no spring---this would use some kind of active position control, with a simple plate on the end of a piston. "no spring" is of course not possible, but could you get the spring constant low enough to push the resonance below human hearing?


"No spring" is certainly possible, you just need a low-friction slip fit. But it's not necessary. For such a servo-controlled system, it's entirely possible to actively damp any such resonances.

http://www.rythmikaudio.com/technology.html

among many others.

How well any of these systems are done is open to opinion. The things that are similar to open-loop systems are still present, like lack of pistonic motion, which is probably the biggest issue/misconception in conventional drivers.

Brett


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 Post subject: Re: The Perfect Speaker
PostPosted: Oct Tue 24, 2017 4:20 am 
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Create a room with good acoustic treatments, diffusion and absorption. These can be accomplished aesthetically pleasing and at minimum expense. Such a room will make marginal speakers sound good, without spending crazy prices. People spend a lifetime chasing amps and speakers only to use them in a boombox environment. Such a pity !


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 Post subject: Re: The Perfect Speaker
PostPosted: Oct Tue 24, 2017 1:06 pm 
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The short of it is there's no one perfect speaker for tube amps.

The best way to get the right speaker is to listen to several in your room with your equipment if at all possible.


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 Post subject: Re: The Perfect Speaker
PostPosted: Oct Tue 24, 2017 4:23 pm 
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Allison 1's and Allison 3's come pretty close.

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 Post subject: Re: The Perfect Speaker
PostPosted: Oct Wed 25, 2017 4:48 am 
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I'm a Celestion Ditton fan... 44's and 15's.
Cheers,
Roger

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 Post subject: Re: The Perfect Speaker
PostPosted: Oct Wed 25, 2017 4:53 pm 
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Some great suggestions so far! Will have to spend some time soon to look up and post some particulars. :)


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 Post subject: Re: The Perfect Speaker
PostPosted: Oct Thu 26, 2017 3:48 am 
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Tube Radio wrote:
The short of it is there's no one perfect speaker for tube amps.



This is generally true, but the problem boils down to a 3-way tradeoff between accuracy, efficiency, and cost. The driving factor with tube amplifiers is due to the relatively feeble output. Tube amps tends to "play bigger" than they actually are capable of to some degree, but that doesn't nearly make up for it and the distortion goes up tremendously with the volume knob. Most of the very efficient speakers are not very accurate of have coloration effects. That might be worth it for the extra efficiency but that's the trade.

With transistor or hybrid amps you don't have to care about the efficiency, you can have arbitrary amounts of power pretty easily and the distortion at high power is really not a consideration.

Cost is obvious, while you can certainly spend a lot of money on poor speakers, to get really good speakers you are going to pay A LOT of money, there is just no two ways about it. Once you get to a certain level of quality, almost all of the extra money goes into trying to wheedle out a few more Hz at the low end, going from 32 Hz to 28 Hz might double the cost from $4000 to $8000 or more.

Brett


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 Post subject: Re: The Perfect Speaker
PostPosted: Oct Fri 27, 2017 6:09 pm 
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Brett_Buck wrote:
This is generally true, but the problem boils down to a 3-way tradeoff between accuracy, efficiency, and cost. The driving factor with tube amplifiers is due to the relatively feeble output. Tube amps tends to "play bigger" than they actually are capable of to some degree, but that doesn't nearly make up for it and the distortion goes up tremendously with the volume knob. Most of the very efficient speakers are not very accurate of have coloration effects. That might be worth it for the extra efficiency but that's the trade.

With transistor or hybrid amps you don't have to care about the efficiency, you can have arbitrary amounts of power pretty easily and the distortion at high power is really not a consideration.

Cost is obvious, while you can certainly spend a lot of money on poor speakers, to get really good speakers you are going to pay A LOT of money, there is just no two ways about it. Once you get to a certain level of quality, almost all of the extra money goes into trying to wheedle out a few more Hz at the low end, going from 32 Hz to 28 Hz might double the cost from $4000 to $8000 or more.

Well said.

30 watts is a typical tube amp, which generally just isn't enough for the kind of realism a more elaborate system can produce. The speaker I use gives respectable volume with about 94 db efficiency, but I use it in a big space, and while it has plenty of bass, there is none of the bottom end 'slam' you get with a modern speaker setup. I figure for that I will have to integrate a separate subwoofer and amp.

So I don't think the high efficiency speakers are necessarily colored, but you do lose lower bass when you try to push efficiency. Balanced sound is lost by pushing efficiency and trying to maintain bass response. It's just not physically possible. This is another argument for reinforcing the bass. I actually plan to try that with my next speaker. I already have the drivers.

Another thing I would like to stress is simplicity and reliability. Aside from realizing the necessity for bass reinforcement, I don't think elaborate servo drivers and amps are really the answer. Yes, they certainly have their place, and some have been very successful like the sunfire subwoofers, but something about having a speaker setup that is more complex than the tube amplifier it is assisting just doesn't make sense to me. I would rather go with more standard components that are more easily repairable/replaceable. I would like any such speaker to be operable for many years, even many decades. This is why I also want to avoid foam surrounds that can rot out and ferro-fluid that can dry out, etc..


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 Post subject: Re: The Perfect Speaker
PostPosted: Oct Fri 27, 2017 6:40 pm 
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I've seen where some will use an efficient speaker open baffle and have a sub directly under it on the same baffle, although the sub is in a cabinet.

Far as a subwoofer amp goes may I suggest either of these depending on how much power you need.

https://www.parts-express.com/dayton-au ... --300-8010

https://www.parts-express.com/dayton-au ... --300-8000

The DSP is helpful in getting the sub optimized for the room and the adjustable HP filter is good.

You can feed it with whatever preamp you desire and use the HF output to feed your tube amp.


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 Post subject: Re: The Perfect Speaker
PostPosted: Oct Sat 28, 2017 3:58 am 
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I was thinking of precisely those plate amps.

I designed a speaker with 99 db efficiency down to about 80 Hz. To match that with the subwoofer driver I picked out will require a subwoofer amp of about 500 watts for a matching output down to about 25 Hz.

In this particular instance I was going to use a Fisher 500. I further determined it should be modified in no way, so the plate amp must be fed by a sample of the Fisher output in some way.

But I still want to get back to the vintage speakers at some point. Perhaps someone else has some information to post?


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 Post subject: Re: The Perfect Speaker
PostPosted: Oct Sat 28, 2017 4:54 am 
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Sol wrote:
30 watts is a typical tube amp, which generally just isn't enough for the kind of realism a more elaborate system can produce. The speaker I use gives respectable volume with about 94 db efficiency, but I use it in a big space, and while it has plenty of bass, there is none of the bottom end 'slam' you get with a modern speaker setup. I figure for that I will have to integrate a separate subwoofer and amp.


In fact, 30-35 watts is about the limit/sweet spot for an individual amplifier, any larger and the inductance of the larger output transformers start rolling off the high end, make the transformers smaller and they begin to saturate at low frequencies. the size of transformers you need for a 30 watt push-pull amp more-or-less splits the difference. Want more, bridge multiple amplifiers together, don't make a single bigger amp.

It's lower for single-ended amps, because of the feeble power of the tubes used and the gigantic output transformers required.

I also agree that all the crazy servo systems are not necessary or warranted, but someone asked.

The solution that no one has mentioned (perhaps because it is obvious, but I have mastered statements of the obvious) - I would look at the heritage Klipsch systems, Cornwall, Heresy, etc, on up to the Klipschorns if you have an appropriate room. They were designed precisely for this purpose, acceptable volume levels with the tube amps of the 50's and 60's. You can get old ones, or have them made to order new. The only others that I would seriously consider are Bozaks, all the way up to the Concert Grand.

Don't worry about damage, if they can build a new one, they can supply repair parts. I used to have some version of the Heresy to use with the various wimpy SET amps people wanted me to build them, I never had a failure of any time (of the speakers, anyway...) and I would play them for 24-48 hours straight for burn-in purposes many times. It was fine even with 2A3s, in fact, I preferred the 2A3 amplifiers (at something around 3 watts) over the 300B (at around 8 watts) in most cases.

Having said all that, however, I have excellent results with a Val Alstine Ultimate 70 (measured at 33 watts) with my B&W 803S (91 db/watt). Anything at 90 or above would be adequate for most purposes in my relatively small room. It plays Virgil Fox records *just fine* and effects in superhero movies and "Band of Brothers" are stunningly powerful, sounds like the house is going to come down. The only limitation is that the very lowest organ tones start getting muddy compared to my prime system, which is a hybrid with 850-900 watts/channel (only extrapolated that one, never had the guts to run it at that level for long enough, those resistors were glowing red). The extra power and much lower output impedance seem to force as much current into it as the speakers want.

Brett


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 Post subject: Re: The Perfect Speaker
PostPosted: Oct Sun 29, 2017 4:40 pm 
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It won't be optimum to do it this way and won't get the ultimate best sound, but at whatever crossover frequexy you choose just insert a capacitor in series with each speaker of a value that rolls the response off at the crossover frequency.

Another option is this.

If the Fisher has a tape loop you can connect the record out jacks to right after the volume control then where the volume control originally connected you can connect the tape in jacks. Then all you need is an OP-AMP buffer between the record out and plate amp. The plate amp will then serve as the crossover.


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 Post subject: Re: The Perfect Speaker
PostPosted: Oct Sun 29, 2017 4:49 pm 
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I like the Magnepan MG IIIA speakers I bought in 1984 ($1,000 each back then) and still have (the planar mid range and bass drivers were rebuilt by the factory): http://integracoustics.com/MUG/MUG/revi ... e_mg3a.htm

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