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Introducing: Clean-Current Speaker with Transformer Aid and Closed-Channel Damping
Introducing: Clean-Current Speaker with Transformer Aid and Closed-Channel Damping
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Old 21st June 2018, 02:34 AM   #11
Scottmoose is offline Scottmoose  United Kingdom
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In theory. In practice it doesn't always work out so pat.

Since the 15w/8434's innate off-axis response isn't especially great out past about 20 degrees I think I'll take a pass.
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Last edited by Scottmoose; 21st June 2018 at 02:37 AM.
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Old 21st June 2018, 08:54 AM   #12
45 is offline 45  Italy
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Quote:
Originally Posted by Scottmoose View Post
In theory. In practice it doesn't always work out so pat.
Sorry to say but this is just the usual approach of the middle ages. Why don't start from the fact that current drive is different and it works in practice if properly implemented? If you don't like it you can tell after you know for real....
The (inefficient) speaker + network in this 3D has been made precisely for that: let people try without spending a lot of money.
Of course you are free to withdraw but you should keep such conclusions for yourself because they are very likely wrong.
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Old 21st June 2018, 09:55 AM   #13
Scottmoose is offline Scottmoose  United Kingdom
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Ah. And there's me thinking that I owned a First Watt F2 for a while and spent some considerable time working with it, while also having a peculiar habit of designing speakers accounting for amplifier output impedance. It must have been a dream. Silly old middle ages me.

You may wish to refrain from making statements about other people's experience in a given field 'for yourself' before checking exactly what it is. If you had, you would be aware of the above and the fact that I actually rather like current drive in certain conditions. 'Sorry to say' however I did not find the wonderful advantages referred to in extending HF response to be an invariant. The Scan midbass in question here is one I am familiar with having used it several times, and its off-axis behaviour > 4KHz is not fantastic, which is the point I was making, since the cone and suspension were never intended to be used over an extended BW and are not optimised for such use. Since this is of some significance in terms of overall performance & sound quality (unless you are nearfield listening only), I have some reservations about its use in this way. As noted, if the OP is happy with the results though, that's what counts.
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Last edited by Scottmoose; 21st June 2018 at 10:18 AM.
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Old 21st June 2018, 10:37 AM   #14
papasteack is online now papasteack  France
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Hi,
Thanks for sharing this.
I don't have knowledge to understand what it is all about, but still, i'm curious, and this offer a way to try something different. In a current project, 4 way active crossed, the mid way 4" got 8db power margin. Should give a try, since it only need few passive component.
Akabak should help simulate this circuit. I've looked at manual, and it seems transformer can be simulated,. I'll give a try when i get time and motivation.
Simulation won't tell anything about distortion, but it should be useful to tweak and see for time integration with the other ways.
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Old 21st June 2018, 11:15 AM   #15
45 is offline 45  Italy
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Quote:
Originally Posted by Scottmoose View Post
Ah. And there's me thinking that I owned a First Watt F2 for a while and spent some considerable time working with it, while also having a peculiar habit of designing speakers accounting for amplifier output impedance. It must have been a dream. Silly old middle ages me.
I have owned current amps and dedicated speakers that really worked as intended. No tricks. They have been produced for about 30 years. A few years ago the company closed down. The only problem with them was the cost. When I moved to the UK I sold them to friend of mines that still uses them and occasionally I can still listen to them. I know the First watt in "current mode" and, in comparison, is poor.

Quote:
Originally Posted by Scottmoose View Post
You may wish to refrain from making statements about other people's experience in a given field 'for yourself' before checking exactly what it is. If you had, you would be aware of the above and the fact that I actually rather like current drive in certain conditions. 'Sorry to say' however I did not find the wonderful advantages referred to in extending HF response to be an invariant. The Scan midbass in question here is one I am familiar with having used it several times, and its off-axis behaviour > 4KHz is not fantastic, which is the point I was making, since the cone and suspension were never intended to be used over an extended BW and are not optimised for such use. Since this is of some significance in terms of overall performance & sound quality (unless you are nearfield listening only), I have some reservations about its use in this way. As noted, if the OP is happy with the results though, that's what counts.
It's mostly about suspensions. For this reason the new FR might not be an exact "lifted up" copy. That is only roughly true. Moreover there is much more to it than frequency response....
As you claim experience can you spec it out? Not in numbers but in basic principles.
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Old 21st June 2018, 11:16 AM   #16
wolf_teeth is offline wolf_teeth  United States
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So is this intended to be used with an average voltage-gain amplifier? I'm trying to figure out the aim of the exercise.

I've thought of using a transformer before on a lower sensitivity woofer to up the system's voltage sensitivity, but I'm not an expert on that and would need direction.

Later,
Wolf
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Old 22nd June 2018, 05:43 PM   #17
ETM is offline ETM  Finland
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Quote:
Originally Posted by wolf_teeth
So is this intended to be used with an average voltage-gain amplifier? I'm trying to figure out the aim of the exercise.
Yes, it's designed for conventional low-impedance amplifiers, to pave the way for getting a taste of the mighty benefits of current-drive without first having to build a current-output amplifier (transconductance amplifier), for which there are few instructions available and even fever commercial products. My site offers some knowledge.

Quote:
Originally Posted by papasteack
Hi,
Thanks for sharing this.
I don't have knowledge to understand what it is all about, but still, i'm curious, and this offer a way to try something different. In a current project, 4 way active crossed, the mid way 4" got 8db power margin. Should give a try, since it only need few passive component.
Hi, naturally the principle is also applicable for individual drivers or groups of drivers in a multiway system, active or passive.
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Old 22nd June 2018, 06:43 PM   #18
freddi is offline freddi  United States
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Introducing: Clean-Current Speaker with Transformer Aid and Closed-Channel Damping
interesting - so the in-band input impedance of the circuit never drops below ~6 ohms. Is a transformer with 1:2.8 turns ratio good for other drivers? If no correction trap is used, is it better to have additional resistance on the primary rather than in series with the load?

also - is using a higher powered solid state amp, what advantages does this approach present vs a simple series resistor?

Last edited by freddi; 22nd June 2018 at 07:13 PM.
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Old 23rd June 2018, 06:22 PM   #19
ETM is offline ETM  Finland
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Quote:
Originally Posted by freddi
- so the in-band input impedance of the circuit never drops below ~6 ohms.
It does drop to ~4 ohms at low frequencies.

Quote:
Is a transformer with 1:2.8 turns ratio good for other drivers?
With that, an 8-ohm load appears as 1.0 ohms and 4 ohms as 0.5 ohms. Quite in the useful range, but the answer is dependent on the current-drive factor desired.

Quote:
If no correction trap is used, is it better to have additional resistance on the primary rather than in series with the load?
Functionally there is no difference, but I don't recommend the latter because the DC current from the amplifier's offset voltage may use up a big portion of the transformer's flux capacity; and even without the DC, the transformer would operate closer to the saturation region.

Quote:
also - is using a higher powered solid state amp, what advantages does this approach present vs a simple series resistor?
No other advantages known than the sensitivity restored. (Both also protect the speaker against DC faults.)

However, if filtering is also used without the transformer, inductance values may become impractically high.
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Last edited by ETM; 23rd June 2018 at 06:38 PM.
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Old 23rd June 2018, 07:51 PM   #20
freddi is offline freddi  United States
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Introducing: Clean-Current Speaker with Transformer Aid and Closed-Channel Damping
Thanks ( from its index, your book appears extremely thorough - wish I had a more powerful brain and better math skills)

With existing speakers which were developed with ~ constant voltage drive, does the principal work best with sealed boxes and open baffles? Simple simulations show response variances as a speaker's input impedance can vary a lot and voltage divider effect minimal at the peaks.

How about front loaded horn systems which have a sealed back chamber? Are simple single ended pentode amplifiers adequate in distortion characteristics to employ for current drive operation ?
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