|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
161.69.14.137
I'm building an active system where a 45-based SET will drive the midrange driver, operating 300/400Hz to 2/2.2kHz. What attributes should I look out for in a driver to make it a good match?
Initially I thought high sensitivity (>100 dB/2.83V.1m) and high impedance, but after looking further into it I'm wondering if those are good starting points.
I see, for example, Lowthers come in 15 ohm, but are "only" 95-96 dB/W, yet are highly regarded for use with SETs.
Tang Band W8 also are higly regarded with SETs and are 93dB/W and are 8 ohm. Yet an AE TD10M also is 8ohm and 94dB/W, a great driver by many accounts, but I have yet to come by a post suggesting it's a great match with a SET.
So what should I look for?
Thank you!
Follow Ups:
You will want a driver with a very high efficiency such that you are using the lowest possible power requirement from the SET. In this manner you will also not limit yourself with respect to dynamic head room.
Thank you all for the good feedback.
Being an active system with the SET directly connected to the driver I thinking I should be able to choose a driver with a relatively flat impedance in the pass band.
I am also going to design with the amp output impedance taken into consideration.
With this in mind, does it make a difference if the driver impedance is flat at about 6 ohm or flat at about 12 ohm?
No difference for a tubed amplifier.
So to take examples: Lowther DX3, widely regarded as a great match for SETs, and Beyma 605Nd, high sensitivity pro driver.
Beyma has higher sensitivity and very low distortion.
Both have a rather flat impedance between 300 and 3000Hz.
Both good choices?
Beyma has lower Mms/BL at 0.76 vs 1.16. Beyma also has higher motor strength.
Lowther has much lower Le @ 1kHz: 0.0035mH vs 0.5mH.
Lowther has much higher suspension compliance (Cms)
How do you guys look at Lowthers spec to know it's a better match for a SET? Or maybe it's not the specs but rather word-of-mouth and actual listening experiences demonstrating they are great performers?
So to take examples: Lowther DX3, widely regarded as a great match for SETs, and Beyma 605Nd, high sensitivity pro driver.
Beyma has higher sensitivity and very low distortion.
Both have a rather flat impedance between 300 and 3000Hz.
Both good choices?
Beyma has lower Mms/BL at 0.76 vs 1.16. Beyma also has higher motor strength.
Lowther has much lower Le @ 1kHz: 0.0035mH vs 0.5mH.
Lowther has much higher suspension compliance (Cms)
How do you guys look at Lowthers spec to know it's a better match for a SET? Or maybe it's not the specs but rather word-of-mouth and actual listening experiences demonstrating they are great performers?
Most tube amplifiers have taps for different speaker impedances. Given that, there is no reason to prefer one impedance over another.
There is a minor consideration, in that some output transformers perform better (have less leakage inductance) on a particular tap. The difference is confined to the very high frequencies, so it is not relevant for a midrange driver. This effect depends on the detailed design of the transformer windings, so only the maker can be more specific.
Other than that, tomservo has addressed the question well. I'll just add that most SETs will have an output resistance between 1/4 and 1/2 of the rated impedance (e.g. 2 to 4 ohms on an 8-ohm tap).
To make life a little simpler for all, you should delete your duplicate thread.:)
Edits: 05/18/17
While generally a good design concept, you're going about it backwards. You should first choose the drivers which will create the soundfield in the room, THEN choose the amps to power them.Also, for best sonic quality, I'd avoid putting a crossover in that 300-400 Hz area, since that is smack in the middle of many musical instrument's range. Better to drop it to 150-200 Hz or even a little lower.
:)
Edits: 05/18/17
The issue with SET's so far as the driver is concerned is that the bass response and to a degree elsewhere is adversely effected by having a significant "source impedance". That source impedance varies from model to model etc. In that way, the variable impedance can cause issues like it does with text book passive crossovers.
While SS and closed loop tube amps have a low output impedance and so are effectively a Voltage source, the Voltage at the speaker terminals will go up and down with frequency, changing the normal frequency response if there is a significant impedance in series. Where the loudspeaker has a low impedance, that will have reduced output, where there is a bump in the load impedance, there will be a rise in output, compared to Voltage driven.
What your would want then is an efficient speaker with the flattest impedance curve you can find -or- find an efficient speaker, measure it on your amplifier outdoors (no room effects) and eq it flat, then move inside -or- using software, design a conjugating network that tames the impedance while minimizing the sensitivity loss.
"using software, design a conjugating network that tames the impedance while minimizing the sensitivity loss".........Tomservo
Is this how you have tamed the SH-50?
Hi Claude
Well no, i really didn't take any pains to keep the impedance constant as most, nearly all who use them have amplifiers that have a lower output impedance like SS, switching or closed loop tube amps.
I have looked at doing that however on other existing speakers and the process can be sped up immensely by using a program like lspcad.
Best,
Tom
I'll be designing an open baffle speaker using an 8" full range driver with super low inductance, coupled to twin Eminence Alphas and an Original Heil AMT tweeter. I can't afford LSPCAD right now, but I can get by without it.I don't ever plan on going back to tubes (left those bias/tube replacment headaches behind in my 20's) but I have tried class AB, Single Ended FET Class A (with tube-like 2nd order distortion products), and soon to be Class D on my SH-50's. So I have none of those non-linear "dynamic voltage divider" issues that are prominently provided by single ended tube amplifications.
I have yet to try Rephase on a MiniDSP since I use a Yamaha Pre Pro for 6.2 and 2.2. BUT, the YPAO room correction does a great job of taming the abundant bass on the SH-50. It still blows my mind that so much bass can come out of such a small horn. In my room, I only need Sub bass below 40 Hz, with my "subtle" TH-50's.
This is still the best sound I've ever had, but I do find the 3D qualities of open baffle speakers to be interesting as a second setup to play with. We shall see.
That being said, I have heard 8" whizzer cone drivers on open baffle and they did sound very good with SET and other amps. Besides, I believe in Room EQ, which would go a long way to tame any frequency/impedance dependent anomalies anyhow.
Perhaps the SET amp lovers need to look to those solutions also.
Edits: 05/20/17
Hi Claude
If you can measure the SH-50's (or anything else) outdoors so you don't have room effects, RE-phase (and a mini dsp) can take you the last bit of the way.
The only measurements i have handy are an sh-50 in my living room at a meter with and without Re-phase's correction impulse.
If you want to try it, i can talk you through if there is a problem
Which miniDSP? Is it the "Open DRC" if so, I'm assuming we want the one that is full digital and no analog?
"I'll be designing an open baffle speaker using an 8" full range driver with super low inductance, coupled to twin Eminence Alphas and an Original Heil AMT tweeter."
There are drivers which a manufacturer or customer can call a "full range driver", but there is no such thing as a full range driver. We've covered this misnomer multiple times in the past. Even "TheTubeGuy1954" gets it now. Moving on...
You should consider using two (per channel) low frequency drivers, wired in-phase. This will give you essentially omni-directional LF output, without the front/back sound cancellation problems from the baffle.
:)
Inmate #51 shall be set free, as he understands !
I don't plan on using it as a full range, but as a broadband midrange with a very light cone and a low hysteresis coil from 200-1200 Hz.(give or take after measurements).The AMT tweeter is currently the one that is most copied, since the patents ran out...........for good reason. 21 square inches of diaphragm, controlled directivity front and back with low distortion AND transient response that rivals horns make it a great candidate for this.
On the bass side, the only bass I have heard that rivals horn bass is open baffle, since it is effectively, decoupled from the room. I regard the "cancellation" as a solution, and not a "problem" as you put it, for the twin 15" woofers I'll be using.
If I were to enclose woofers again, I would go back to my Quarter Pie Horn design, which I shared the the Klipsch Forum to over 50,000 views. It's been built all over the world with great success. Been there, done that, want to try other stuff for fun.
Klipsch Theater Horns with TAD drivers, Horn bass and, most recently all Danley tapped horn and synergy horn products are my reference standards, not the overpriced stuff at "high end" shows. I regard Open Baffle speakers as the antithesis to horn systems, so I want to hear both ends of the product spectrum. I'm pretty sure I will be giving up horn DYNAMIC IMPACT for 3 Dimensional depth, but it's a worthwhile experiment with cheap and used drivers and cheap lumber recycled from Cherry wood desks I got at Salvation Army for 40 bucks!
Edits: 05/20/17 05/20/17
The loudspeaker cabinet.
This part is really a problematic component. It plays its very important role in
separating the sound
from front
and backside of the units.
Any attempt to mix them, no
matter how, will result in wrong reproduction.
As far as I can see, the "expert by self proclamation and publication," to whom, you bow, is merely parroting the design philosophy of B&W, whose many designers have come up with clever ways to maximize their custom moving coil driver performance in various sealed/ported box configurations, including their "Matrix" box stiffening methods, which are technically sound......no pun intended.
Then you use this unpublished parrot writing whose author did not withstand the peer reviewed aspect of the Audio Engineering Society as a basis to criticize something that has been BUILT successfully by others who have, obviously, a broader band of knowledge regarding all speaker types, including the B&W offerings, which are more space heater than loudspeakers with their limited dynamic range and flammability when a 30 db watt amplifier is employed in an attempt to derive a single acoustic watt of output without gross IM distortion or burning the house down.
On the cheap AN FR.
Inmate Claude shall remain locked up, for he exists in a non-reality:
"On the bass side, the only bass I have heard that rivals horn bass is open baffle, since it is effectively, decoupled from the room. I regard the "cancellation" as a solution, and not a "problem" as you put it, for the twin 15" woofers I'll be using."
Really ? bass cancellation is the solution to bass ?
(Is there a doctor in the house?)
Yes, that is how a 1/4 wave based, (Figure 8) pattern is created, like the H box as cited by Martin King's papers. The bass that is cancelled is the bass that would emanate on the sides, where it's not needed or wanted. By spacing the cabinet far away from the front and side walls, the rear bass arrives at the listener greater than 20 milliseconds in time. Open baffle speakers have a pleasant 3 Dimensonal presentation that is uncanny.
Go read the work of Sigfried Linkwitz, of Linkwitz-Riley filter fame on open baffle for technical details that required many years of work on his part.
Instead of criticizing something you have never tried, you might want to go and build one, then compare notes with those who have done it.
Fair enough?
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: