Tom Danley mods for Altec VOT A7?

[mcds]

I understand Tom Danley once proposed some mods to the A7 which are supposed to improve the sound greatly. I couldn't find anything on the net, and paging Tom on AA brought no result.

Anybody happen to know where I could find further info?

[louped garouv]

there's an old Sound Practices article by Jim Dickinson that you may want to search out also....


if you can still buy the Sound Practices Archive CD on Ebay, I thought it worth the admission price....

[mcds]

there's an old Sound Practices article by Jim Dickinson that you may want to search out also....


if you can still buy the Sound Practices Archive CD on Ebay, I thought it worth the admission price....

Thanks, I'm aware of the Sound Practices article as I have a full collection of the mag. However, according to an old thread on this very forum, Tom Danley said somewhere that his mods take several hundred degrees of phase distortion out of the design, an aspect which is not covered in the SP article.

[JBLRaiser]

Thanks, I'm aware of the Sound Practices article as I have a full collection of the mag. However, according to an old thread on this very forum, Tom Danley said somewhere that his mods take several hundred degrees of phase distortion out of the design, an aspect which is not covered in the SP article.

what do you need to know?

[mcds]

Here's the info that can be found on the Altec User Board:


A-7 mods

Replace stock drivers with JBL-2226 and BMS 4550.

Replace lower vent panel with one having 4 , 4 inch dia ports, 5 inches long.
Pic #60

Reinforce 15” horn flares, glued in with construction adhesive not wood glue or epoxy.
I used boards which were 5 ½ inches by 12 inches with one side cut to a 20 degree angle to better mate with the horn flare.. These are way too live.
Shown in pic # 62
Before and after is shown in measurement, gets rid of a few dips.

Optional, it wouldn’t hurt to put a 2X2 diagonally on the lower cavity side walls with a 2X2 added to tie the sides (from one side to the other) together.
I would use construction glue to adhere the 2X2’s to the walls and when dry, use screws to attach the cross brace.

Apply damping to the under side of the final bell of the 511 (not visible).
Mount the horn on the rear side of the wood, setting it back from stock.

Mount the 15’s with an extra front gasket for clearance at Xmax.

Use foam tape to seal all removable panels and replace the wood screws with 1 5/8 drywall screws.

Drizzle some extra glue at the front edge of the flare on the interior (the glue joint at the front where the bent plywood attaches. Use that gorilla glue (polyurethane) for this as it fills gaps. On this one there was a gap in the wood (on the inside).

Remove and remount the horn mounting board, remount 2 ¾ inches rearward and use the foam tape under it (which dampens the box top panel).

I'd love to see the pics, of course, but most importantly, I can't imagine that TD did not make any suggestions for the crossover.

Also, which version of the 2226? Not sure I'd go with the BMS, but TD usually knows what he's talking about.

[Zilch]

Not sure I'd go with the BMS, but TD usually knows what he's talking about.Unity horns are built with BMS 4550s, I do believe.... ;)

[robertbartsch]

I've used the JBL 2226 and various Altec VOTT woofers including the 411 and 416. Its weird to me that he would suggest replacing an Altec woofer with a JBL but, weirder things have happened, I suppose.

[spkrman57]

The cabinet is way too large for a small Vas driver like the 2226(I think about 7 ft from memory).

I think there are better drivers to use in the A7 VOTT cab.

Regards, Ron

[Zilch]

The cabinet is way too large for a small Vas driver like the 2226(I think about 7 ft from memory).Allegedly, it is a horn.

The friend he did that for already had the drivers; Danley said he'd have used something cheaper. That narrative is on Audio Asylum, as I recall.... :yes:

[mcds]

TD's original post from AA which Zilch alludes to, and which is quoted somewhere in the archives of this forum can be found here:

http://db.audioasylum.com/cgi/m.mpl?forum=hug&n=82503&highlight=2226+4550&r=

Since TD specifically mentions "several hundreds of degrees less phase shift through crossover", I'm thinking he must have done something to the crossover as his work on re-aligning the BR wouldn't change the response at the crosover point.

Now, to my mind, there's two possiblities: either TD found that with the existing crossover but different drivers, the phase shift through crossover was less; unlikely.

Or he changed the crossover schematic. This is what I'm trying to find out. Any help is very much appreciated.

[A9X]

Unity horns are built with BMS 4550s, I do believe.... ;)The original Lambdas had TAD 2001 or B&C DE25 (what mine have). The current Synergy's use the 4553 and other BMS from all I have read.

[Russellc]

Here's the info that can be found on the Altec User Board:



I'd love to see the pics, of course, but most importantly, I can't imagine that TD did not make any suggestions for the crossover.

Also, which version of the 2226? Not sure I'd go with the BMS, but TD usually knows what he's talking about.
Well I can tell you one thing, when you hold a 2226H or 2225H driver up to the hole in my 828 A-7 cabs, you're going to need a hole shrinker! Driver aint quite as big as the original I have, 416 8C and 515 8G anyway......

Russellc

[Zilch]

Danley posted this two days ago:

http://www.diyaudio.com/forums/showthread.php?postid=1870178#post1870178

The larger issue is the HF response, and Don McRitchie documented A7's "haystack" tuning. That keyword will find Don's post.

My best answer to the crossover question is the reconfiguration of the Model 19 crossover I did in Skywave's 9844 thread here, but even the "HF capable" Altec drivers exhibit a significant ripple when compensated, at least the 802s and 902s I measured. The BMS is higher sensitivity, so to bring it into the operating range of the dual controls, an additional fixed L-pad may be required.

No, I never ran it with 2226H as the woofer, and no I don't have any A7s to try that.

I extensively documented how the Model 19 crossover works here. Keyword "Gary" by Zilch will find it, "Here go, Gary...."

Bottom line, based upon my analysis, upgraded A7s begin with empty cabs, and after all of that, they'll still need subs....

[Goodwill_HiFi]

Bottom line, based upon my analysis, upgraded A7s begin with empty cabs, and after all of that, they'll still need subs....

Then they're not A7's, they're 828 cabinets with a variety of purposely chosen components installed.

[Zilch]

Then they're not A7's, they're 828 cabinets with a variety of purposely chosen components installed.Naw, they still have Altec sectorals, but we can work on that part, too, of course.... ;)

[Mr. Widget]

I hadn't read this thread until just now... it would seem to be rife with confusion, misinformation, and speculation. If you really want to know what suggestions Tom Danley has made regarding A7 mods why not ask him?

http://www.danleysoundlabs.com/

If the goal is to get the best out of your A7s, probably a better tack would be to follow some of the threads on Todd White's Board where the real Altec experts live.

http://www.hostboard.com/forums/altec-users-board/


Widget

[mcds]

Mr. Widget, thanks for taking the time to respond. My friend merlin speaks highly of you.

Somewhere on his website, Tom says he's unable to answer questions like mine. I still paged him on AA but he either didn't see it or chose not to respond. Fair enough, I'm sure he has more pressing needs to address than questions from complete strangers.

I'm a member of the Altec board and posted the same question there. Unfortunately, noone had more than I've posted here, either.

What specifically attracted my interest is the comment about phase.

Zilch, with all due respect, I'd rather use a 2405 on top rather than extend the FR of the hf driver. But thanks very much for the diyaudio links, I had not been aware that TD posted there and have started reading up on his old posts there.

[Earl K]

Hello mcds,


What specifically attracted my interest is the comment about phase.

- I concur with Widgets' advice for you to find a way to contact Tom Danley to obtain some clarification about his past comments about phase distortions ( re ; his A7 mods ) .

- I fear you may have read too much into something Tom D. said which might have been just an "off-hand" comment relating more to the superior UHF performance of the newer generation of drivers ( & not at all related to phase issues within the crossover area ) .

- For instance ; One result of using drivers with extended HF performance is the need for less radical HF (EQ ) contouring ( to flatten the HF response ) . Less HF EQ applied results in smaller phase changes within the HF region ( this might be what he was referring to ) .

>< cheers :)

[rlsound]

The larger Danley designs use Faital HF drivers. At least the SH95 does.

[Mr. Widget]

The larger Danley designs use Faital HF drivers. At least the SH95 does.Here is the site... had to check it out as I had not heard of them before.

http://www.faitalpro.com/products/hf.php


Widget

[Zilch]

Tangerine! :D

http://www.faitalpro.com/products/schede/cd.php?id=502010200

[mcds]

Hi Earl,






- I concur with Widgets' advice for you to find a way to contact Tom Danley to obtain some clarification about his past comments about phase distortions ( re ; his A7 mods ) .

Agreed, but unfortunately, I have no idea how to do this.


- I fear you may have read too much into something Tom D. said which might have been just an "off-hand" comment

Entirely possible.



- For instance ; One result of using drivers with extended HF performance is the need for less radical HF (EQ ) contouring ( to flatten the HF response ) . Less HF EQ applied results in smaller phase changes within the HF region ( this might be what he was referring to ).

The stock Altec crossover (N501) doesn't use HF contouring, it's a text book symmetrical 12 dB/octave design.

Maybe I really am reading too much into this.

Markus

[Ian Mackenzie]

I would pm cyclotronman (Kent) who has extensive expierience with modifying Altec systems.

Earl also has good handle on this stuff.

Years ago I read an article by Triode System who as I recall who did modifications to these types of systems.

Steve Schell would be another member to contact.

Ian

[Mr. Widget]

I would pm cyclotronman (Kent)...It's Cyclotronguy. :)


Widget