Altec 9844-8B

[iosif]

I have completed missing RTA from last test, and made additional with BMS 4552ND on N-800-F and M-19-Z in 2.0 and 2.5 woofer modes.

Next I will do a listening shootout in mono between 902 HF on N-800-F and BMS on whatever x-over sounds best with that. Both 2.0 and 2.5 will be compared.

All of it will be posted together.

In the interim I have gotten fuzzy on the 2.0/2.5 modes which I was clear about last month.

Do I understand this correctly: In 2.5 with 20mH in line with helper woofer, the crossover sees 16 Ohms down to the crossover region, when lower frequencies engage the helper and the inductor essentially allows both woofers to play in parallel, 8 Ohms.

Looking at Zilch’s sims:


Green and yellow are 8 Ohms. ERROR: PLEASE READ POSTS ABOVE!

In helper mode, the crossover region in the low pass appears to be significantly boosted by maybe 8dB in the upper bass, really lower mids, whereas when 1 woofer is operating (16 Ohm), you'd have an 8 dB contour cut there. A boost lower down would occur when both woofers kick in.

Do I have this right? ERROR: PLEASE READ POSTS ABOVE!

Dear Rider

Would you help me please with scheme of crossover for BMS 4552nd on Fane colossus 12mb

Thank you

Josef Mazur

[Skywave-Rider]

I don't know what horn/waveguide you are using, but if you read this thread you see that I did not need additional HF compensation on the 811B with BMS 4552nd. This was using the N-800F crossover, stock, in the 98448B, 8 Ohm woofer load, 8 ohm 4552. On my RTA the frequency response looks pretty flat from the horn.

The N800F schematic is posted in this thread.

If you are interested in the JBL PT waveguide which has been discussed in the thread, the BMS works great on that employing an HF compensating circuit developed by Zilch. I will re-post it here and credit goes to him.

Heeding further advice from me in the realm of crossover design could prove hazardous.
PS: any relation?
http://en.wikipedia.org/wiki/Jozef_C._Mazur

[Russellc]

Hi Zilch and Skywave

Reading through that long Ak thread, I came upon an interesting comments about my 811bs being gonadotrophic. Well, I am willing to try a couple of waveguides with d210 or d220. So what's the verdict? BMS being the best and how are d210 and d220 differ?

Hey Zilch, Perhaps the altec people would love to make some comments on your comment about the 811b and 511b?
Well, you get the point.

MrT!

He told me the same thing about the 511B on my A7s when I asked if the wave guide could keep up.....it did and bests it considerable in HiFi terms.
811b and 511B still tops for gonadatrophic effects!

Russellc

[MrT]

I think you're right. I've ordered a couple of waveguides and d220tis. My first choice was BMS but, i could not get email replied and other store did not "endorse" bms. After a weeks of waiting in frustration, I came upon the AK waveguide thread. Actually, I am pretty excited. I wanted to register at AK but admin turned it off. So, I am waiting.

MrT

[felixx]

Any news with d220 + waveguides?

[Skywave-Rider]

Plenty of news here:
http://audiokarma.org/forums/showpos...&postcount=228

[felixx]

I put 811 horns + 806 driver + Fostex T925A to work and I compare those with Supravox 215RTF Bicone (full range driver) into open baffle.
Both was augmented with 2 Eminence Alpha 15A per side (15").
All into 20m2 listening space.

The maximum sensitivity on Altec is about the same with Supravox...96-97db.
The details on Altec was a little soft and silky and a few steps back, somewhere close to the wall.
The feeling on Supravox was "right in my face" the vocalist was "here..here with me".Allmost I touch the instruments.Microdetails was there.
The single "weak link" on the Supravox was when I go up the volume.. ...aprox. 45W ...(on 96db spl)...the sound became ugly agglomerate,harsh and unpleasant....but on 30W is amaizing.
On jazz or classic music the instruments on Altec horns was something on the back seats comparing with Supra on the baffle but easy listening on higher volume.
I change 806 with Selenium 220TI,2500Ti-neodimium and BMD450-S ferofluid from PAudio.
The 2500 is a little dark,220TI something dull and 450 in between...
All these drivers don't go up enough,the mark -"metal inside"- was not my cup of tea ,something still missing comparing with Supravox.I don't tryed the drivers on other horns.

So,my question is if that feeling to be a little behind on 811 is because of the 811 or is specific to all radial horns?
The feeling -"metal inside"- was on all drivers.
Any thoughts?

[Zilch]

So,my question is if that feeling to be a little behind on 811 is because of the 811 or is specific to all radial horns?
The feeling -"metal inside"- was on all drivers.
Any thoughts?

Unless you have measurement capability and can normalize the frequency responses, you are shooting crap here....

[speakerdave]

. . . .
Any thoughts?

I think the veiling you are talking about, if I understand you, is often blamed on the interdiction the crossover performs on the signal, by the Full Rangers, that is.

What Z-man said--you really must know whether what you're hearing is caused by frequency response anomalies before you can make well-based judgments about the sound quality of various components.

I think some people have had success restoring the tactility and soundstage of full range drivers, and getting better frequency response and less IM distortion, by carefully designing the crossover and other factors of the relationship between drivers, and choosing very fine compression drivers, like the JBL 2452SL, the recent JBL beryllium models, and some of the TAD's.

[Skywave-Rider]

Although my Altecs don't use any of the components you are integrating apart from the horns, I may know what you mean by "the sound a little behind."

That is that the sound apparently emanates from behind the baffle, if I read you correctly. Of course the HF does, but I don't know the answer to your question however.

I tried the 220Tis on the horns and found after listening and looking at their response, that they can't work without a new crossover in these speakers.

Take some readings.

[felixx]

Although my Altecs don't use any of the components you are integrating apart from the horns, I may know what you mean by "the sound a little behind."

Comparing face to face,that was my impression.I know the conclusion is too early.The crossover for drivers was only N800.
The integration of Fostex T925A with 811 is acceptable good.
But the feeling on these 811..."somewhere behind" comparing with "here in my face" is my concern before I go to spend on other radial horns and compression drivers.

Happy Holidays to all.

[pcchipvn]

Comparing face to face,that was my impression.I know the conclusion is too early.The crossover for drivers was only N800.
The integration of Fostex T925A with 811 is acceptable good.
But the feeling on these 811..."somewhere behind" comparing with "here in my face" is my concern before I go to spend on other radial horns and compression drivers.

I doubt your problem is because of the arrangement of the 811 horn. Although you use N800 X-over but the arrangement can cause phase problem at the crossover point (especially the phase between the woofer and the 811horn).

[stuck.wilson]

I doubt your problem is because of the arrangement of the 811 horn. Although you use N800 X-over but the arrangement can cause phase problem at the crossover point (especially the phase between the woofer and the 811horn).

i had difficulty with this myself... but i'm not using an 811 with my 4552nd-- but a wider dispersion fiberglass horn. no matter HOW i seemed to align the horn, i couldn't make them sound coherent with the n800f 2nd orders! for the most part, they sounded 'clean'.. but tonally something didn't work.

i'm probably speaking out of turn, as i'm not really equipped as a measurer, and the good folks around here with RTAs have done me a very good turn- so absolutely no offense meant to them is intended! but in dealing with my horn-- i took the bottom half of the n800 (the low pass on a 614 cab with a 414b in it), and reassembled the 'top half' as a first order filter (wired reverse polarity, with 12uF and an lpad) recently... and it really opened up a LOT. could be my horn, could be broken ears.. i dunno.. but it sounds SO much 'easier' to me... and i'm really a fussy old grump about too much top end, as witnessed by wanting to ditch my 4552's for a while.. 'course, i've got 15 watts on tap too, so not much worry of blowing my drivers either!

NOW though... the balance is pretty wonderful- very even keel and smooth, and imaging is fairly outrageous.... but like i said-- could very much be preference over science- and i don't want to give the impression that i disrespect the work of zilch or skywave a bit! from my non-measuring impression though.. not a bad mix! the second order DID do my 414 a fantastic turn!

[Zilch]

You've GOT to use HF comp to dial it in "right."

[Skywave-Rider]

If anybody's interested, some 9844 cabs, not "B" versions, on ebay.
No affiliation, of course.
http://cgi.ebay.com/ws/eBayISAPI.dll...E:B:SS:US:1123
Yes, they're in Kalifornia.