EDINGDALE speaker build

Dedicated to those large boxes at one end of the room
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Toppsy
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#91

Post by Toppsy »

Planet10 wrote
I have no disagreement there. What i supposed to be implicit in what i was saying was that the MA wasn't suited to this application
Dave,
I thought I had made that point
The MA T#3 (ERT26) maxs out at around a published 92dB. And it is here I think the tweeter is struggling.....................So I can only assume it's down to trying to ask a little too much from this fine (and cheap) unit.
At least we both agree that for these speakers the MA Tweeter is struggling and the 98dB ribbon suitably attenuated is a far better match. So I can at least get rid of the "offending" resistor and wire staright back to the XO through the L-Pad attenuator.
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Ali Tait
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#92

Post by Ali Tait »

It sounded very good, there was only the problem of a little sibilance to my ears, but then I'm running OB's with B200's and no tweeter, so I just may be more sensitive to this kind of thing now. Imaging was first rate, and I mean first rate, I've never heard a large floorstander image so well.
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#93

Post by Toppsy »

Chris661 wrote
Methinks to avoid such messing around, a true L-pad should be used: one resistor in parallel with the speaker, another in series to keep the impedance the same as the original.
I think Chris you are missing whole point of the exercise/experiment. Please re-read my postings on the relative SPLs of the 4 mid-woofers and the MA tweeter.

So armed with this data why would I want to intentionally attenuate the tweeter any more with a L-pad? The whole exercise was an attempt to tame the sibilence with as small a resistor as possible. This it did but in doing so it also reduces the SPL by -1 dB. Too much for the tweeter to gell completely with the woofers. So as Dave has qualified his earlier post, the MA tweeter in this application is not wholly suited.
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#94

Post by chris661 »

I was under the impression that we were talking about the crossover to the ribbon, with a series resistor.

I'm still unsure about why the MA tweeter wouldn't sound so great with additional woofers: it worked fine even under considerable power last Owston.
Whatever. It sounds like progress is being made, which is the main thing.
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#95

Post by Toppsy »

I was under the impression that we were talking about the crossover to the ribbon, with a series resistor.
Confused you are young skywalker. NO. The experiment with the series resistor was on the MA TWEETER NOT the ribbon. The ribbon does NOT suffer from the sibilence of the silk dome tweeter. But then the ribbon is wired through a adjustable L-pad attenuator.

The problem as I see it is with the 4-woofers the SPL is upped to around 93dB from a single mid-woofer SPL of 87dB. The tweeter max SPL is around 92-93dB depending who you talk to.

In the 2-way standmounts there is a true L-Pad to attenuate the silk dome down to 87dB. In the Edingdales the tweeter (silk dome) is run unattenuated.
I can only assume that the MA tweeter benefits from the addition resistive load and without such can get and does get sibilent.
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#96

Post by chris661 »

Toppsy wrote:
I was under the impression that we were talking about the crossover to the ribbon, with a series resistor.
Confused you are young skywalker. NO. The experiment with the series resistor was on the MA TWEETER NOT the ribbon. The ribbon does NOT suffer from the sibilence of the silk dome tweeter. But then the ribbon is wired through a adjstable L-pad attenuator.

The problem as I see it is with the 4-woofers the SPL is upped to around 93dB from a single mid-woofer SPL of 87dB. The tweeter max SPL is around 92-93dB depending who you talk to.

In the 2-way standmounts there is a true L-Pad to attenuate the silk dome down to 87dB. In the Edingdales the tweeter (silk dome) is run unattenuated.
I can only assume that the MA tweeter benefits from the addition resistive load and without such can get and does get sibilent.
I see. Possibly. You'll have to excuse me, its been a long day.

The L-pad device you're using on the ribbons is made up of two resistors to give something like this...
Image
Except variable. You get the idea.
Yes, that would make more sense.

I think I'll get some sleep now - the weather's cooled off a bit now.

Chris
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Nick
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#97

Post by Nick »

Frequency=impedance/2pi*inductance
Frequency is proportional to impedance.
Yes, and inversely proportional to impedance. So again, if the resistance of the tweeter is increase, the crossover frequency will go down.

All those two equations are doing is keeping the RC and RL points the same.

Any chance of that complexity you promised yet?
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#98

Post by Toppsy »

The L-pad device you're using on the ribbons is made up of two resistors to give something like this...

Except variable. You get the idea.
I was never confused and got the idea and makeup of an L-pad circuit many moons ago. This is the adjustable L-pad I'm using on the ribbons:


Image

On the 2-way standmount Edales the L-Pad is fixed by a couple resisitors as per your attached diagram.

BUT the whole issue of debate these last few posts has been the statement by DaveD that the series resistor, I tried in the experiemnt on the Silk Dome Tweeter,
reduces the level and pushes up the XO frequency.

The bit of the quote in contention and what Nick has been contesting being that in BOLD TEXT . And the fact you stated it is complicated. Again something Nick is contesting to what complication :?:
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#99

Post by brig001 »

Chris asked me to upload this.
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Nick
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#100

Post by Nick »

And the gain at 4.5k looks exactly the same in both cases.

If we take the gain at the right hand side of the graph as 0dB, then the level at 4.5kHz is more with the 10 ohm in series than without. Having more output at and below a frequency looks to me like the effective cross over frequency has gone DOWN not up.

I am more than happy to be shown where I was wrong in my understanding,
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#101

Post by chris661 »

Yes, the crossover point (chosing, say, the -6dB point) has reduced in frequency. The complications I talked of (where the attentuation from the inductor and capacitor don't happen at the same frequency) seems to have resulted in a peak in the output, instead of simply moving the curve further left.

Chris
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#102

Post by brig001 »

I'm afraid it's worse than that. The whole point of a crossover is to provide a flat sum from the two drivers. This relies on phase and amplitude, and if you use a crossover with the wrong load impedance, the phase will be wrong, which will make the vector sum wrong whatever the amplitude graphs look like.

Anyway looks like it's all sorted with the ribbon tweeters, and I am looking forward to hearing these.
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Nick
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#103

Post by Nick »

Yes, the crossover point (chosing, say, the -6dB point) has reduced in frequency.
So, given that the point I was questioning was that increasing the load resistance would cause a LOWER cross over frequency, you agree with me then?
The complications I talked of (where the attentuation from the inductor and capacitor don't happen at the same frequency)
With respect Chris, you didnt talk of any such thing, you simple said "its complicated" and pointed to a web page.
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#104

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Nick wrote
So, given that the point I was questioning was that increasing the load resistance would cause a LOWER cross over frequency, you agree with me then?
Glad that's all sorted and we are ALL now in agreement.

So back to the speakers in question.

Yesterday I did the mods to the front baffles to replace the MA tweeters with the ribbons and also installed the L-Pad attenuators on the rear baffles. I am using the existing XO with no modifications. So the robbons are corssing over around 3.5kHz.

I always knew from the first moment I fired these up there was potential for a great speaker in the making. However in some respects and especially with the sibilence from the 1" silk dome tweeter with a max SPL of around 92dB and the overall speakers being 93-93dB efficient it was just asking too much of this tweeter in these speakers. I now believe this slight mismatch, with the tweeter, had been holding back what was (and now is) a great speaker stuggling to get out the boxes. However having said that they did sound rather GOOD. And I do mean GOOD in that incarnation.

But now with the ribbons in place I must say these have leapt up a notch in overall sound. They have he same deep quality bass, but Oh that midrange. So clear and detailed. I don't think I have heard better midrange from any other conventional box speaker. They do remind me in this respect to my venerable Quad ESL63's and 57's. But, the HF has now taken on a wow factor to add to the mix. Overall and with the little 300b SET's they do sound FANTASTIC (to my ears) and definitely the best speakers I have produced to date. :lol: :lol:

Here's a couple photos of the reconfigured driver set up in my listening room.

Image
Image
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#105

Post by chris661 »

Nick, I may not have said so immediately (because I didn't know exactly what would happen, just that you wouldn't end up with the same curve as with the intended load), but I did say the crossover points for each components won't be aligned any more:
chris661 wrote:
I'm fairly sure Colin has a 2nd order filter. So the actual crossover points (for cap and inductor) will diverge, giving an unintended result.

Chris
I hope this clears that up.


Colin, I have to say that, even in their unveneered form, they certainly look the business: the ribbon tweeter gives them a somewhat high-end look.
Can't wait to hear these: have you tried them on a big ol' solid state amp?

Chris
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