Speakers finished

salva · « **on:** 30 Apr 2004, 09:57 pm »

You can see photos here:
http://www.videoacustic.com/sferrairo/1801_final/

I'll post my comments tomorrow

Salva

salva · « **Reply #1 on:** 1 May 2004, 11:13 am »

OK, overall sound is good, very good. I'm not use to high end hifi stuff but I've to say that those speakers sound better than anything that I've ever heard.

Only small complain is that one of the woofers did a small "rattling" that went away after a period of break in.

If you are planning to do those speakers to hear low quality records, think again, the 1801 have the ability to do the good recors to sound better but the bad recors will sound horrible. They will reinforce what good or bad is in the record.

And, one last word ... think abt this ...

If you plan to do the 1801, enjoy your time and learn new things during the process you are on the rigth track, but if you are only going to do them just to save some $$$ don't do it, you better buy something in a shop. If you are a little bit perfectionist (as I am) this proyect will take 3 or 4 times more time and effort that you thougth on the first place.

Salva

tybee · « **Reply #2 on:** 1 May 2004, 06:37 pm »

Nice job on your 1801s. Since I do not have the skills to build these wonderful speakers, I commissioned Darren Thomas to craft a beautiful pair of walnut 1801s.

Your comments on the 1801s sound mirror my experiences with the 1801s. They will reveal shortcomings in the record or cd, but they do a great job on better recordings. I have currently matched the 1801s with an Anthem CD1 with a highly modded Jolida 502B integrated tube amp. This combination continues to bring a smile to my face.

Welcome to the 1801 club.

David Ellis · « **Reply #3 on:** 2 May 2004, 07:00 pm »

You gotta' Anthem CD-1, eh. Is it modified? If not, I have some very inexpensive swaps that will produce amazing results in that player.

We might have already addressed this, but I am not sure.

Dave

tybee · « **Reply #4 on:** 3 May 2004, 02:18 am »

Dave,

Please do give me the details for improving the CD1?

David Ellis · « **Reply #5 on:** 3 May 2004, 02:37 am »

I'd rather dicuss the mods with you on the telephone. The mods are pretty simple, but getting them all down on paper would take considerable time. Please send me your telephone number. I should have time to call you Monday/Tuesday night.

[email protected]
402 991-8528

salva · « **Reply #6 on:** 4 May 2004, 09:47 pm »

Hi, today I've measured the 1801b in the anechoic chamber, here you have some photos of the measurements (high resolution)

http://www.videoacustic.com/sferrairo/1801_anecoica/

Response speaker one, on axis http://www.videoacustic.com/sferrairo/1801_anecoica/graphs/1801_front_F.wmf

20 Degress http://www.videoacustic.com/sferrairo/1801_anecoica/graphs/1801_20_deg_F.wmf

45 Degress http://www.videoacustic.com/sferrairo/1801_anecoica/graphs/1801_45_deg_F.wmf

Response speaker two, on axis http://www.videoacustic.com/sferrairo/1801_anecoica/graphs/1801_second_F.wmf

Wich surprised me a little bit is the small (3db) rise in around 400 / 800 Hz

OK, Anyway ... enjoy the measurements

Salva

salva · « **Reply #7 on:** 4 May 2004, 09:52 pm »

OK, I just re read the specs on the W18 and my measurements seems to correlate with the specs of the w18

http://www.seas.no/excel_line/excel/E0018.PDF

See the efects of off axis in my mesurementes and in the datasheet.

Salva

David Ellis · « **Reply #8 on:** 5 May 2004, 01:45 am »

What was on the floor of the chamber, and what kind of signal was used?

Dave

salva · « **Reply #9 on:** 5 May 2004, 07:10 am »

We used MLS on the measurement, we tried sweep as well with same results. The microphone was a BK.

The material on the floor (same of the walls and ceiling) are abrorbent triangles designed for anechoic chambres.

The speaker was on a table and over a mattress of absorbent foam.

Salva

Ravi · « **Reply #10 on:** 5 May 2004, 07:45 am »

I would love to see similar response measurements of some other popular speakers on this forum. I think the Ellis response would humble quite a few of them

David Ellis · « **Reply #11 on:** 5 May 2004, 01:28 pm »

Well,

I am not disturbed, but am very curious. Even if there is a bump in that region, it's pretty small. I'd like to try and replicate that response, but am not sure I'll be able to accomplish that . I am also totally clueless about how the W18 driver could create that contour in the response curve. It's a very bazaar plateau. The Scan drivers notoriously have a a small ripple in the response around 800-1000hz.

My mic is calibrated, and Dennis's mic is calibrated too. Both yield the same response for the 1801. Neither indicate that little plateau. I am perplexed. I don't think the plateu is terrible though - only 2-3db.

I think there might be some folks who could provide some insight on this matter. I'll subject the first graph to the folks on the madisound page.

A few more questions first:

What was the measuring distance?

What was the microphone/tweeter height?

What are the room dimensions?

Was the MLS response gated?

Do other speakers exhibit the same phenomena from that measuring location?

I really appreciat the graphs. They are great. I'd simply like to assess the measurement setup before searching for the "bug" in our measurment jigs. The latter could be VERY exhaustive.

Dave

salva · « **Reply #12 on:** 5 May 2004, 06:39 pm »

OK, I'm curiosus too, the graph is better than anything we have measured. The mic is a BK (one of those that costs 1200 $) and we have tested as well against a BK Sound source.

We did the measurements both in MLS and in Sweep to rule out problems in the measurement Jig. Both speakers did measure exactly the same.

OK, The thing is that the datasheet for the driver seems to have a rise on the same region.

I Dave, will like to know exactly your measuring scenario (Soft, placement etc), so that I can try to reproduce it to see how it goes.

Measuring distance 1,20 mtr

Microphone centered between tweeter and woofer

Yes the MLS was gated

And other speakers do not show that behaibor.

Salva

David Ellis · « **Reply #13 on:** 5 May 2004, 06:50 pm »

Well,

I measure at darn near 1 meter - about 39-40" generally. The tweeter is about 40" from the floor and I use a gated MLS response. I generally set the window to COS, but this shouldn't be significant.

The lower limit of my response is generally 278hz. This is limited by the gate function and the wavelength extant. The direct wave is clipped before the reflected wave arrives.

I should be doing some testing this afternoon/tomorrow. I have a pair of speakers to finish for a gentlemen. Maybe I'll fiddle with the setup a little and try to find that bump.

Well, the 3db rise looks like the real deal. The thing that really puzzles me is the shape of the bugger. The SEAS factory graph shows a nice curve, but your graph looks like a plateau. Yes, it's a small plateau, but I'm anal.

I'll go ahead and post the graph on the madisound page for the "jury" inspection and deliberation. Hm, maybe Phil Bamberg knows something.

salva · « **Reply #14 on:** 6 May 2004, 05:11 pm »

OK, now that I've seen the lining of your speakers, I have seen how you do it and I only did the center region on my speakers. No batting as well

Coudl be that this difference in lining creates sone resonance that you see on the graph ?

Salva

David Ellis · « **Reply #15 on:** 6 May 2004, 06:02 pm »

I thought about the impact of the stuffing on your response graph. I don't really think this is the issue. Bumps in the response due to lack of stuffing normally correspond with the axial wavelength between the cabinet walls. While there are many modes, the axial mode is most prevalent.

The vertical height of the cabinet roughly corresponds to your response, bump, but this is questionable. It is worth consideration, but I cannot promise stuffing foam on the top & bottom will fix your problem.