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-   -   Old School Studio Monitor Build (https://www.avsforum.com/forum/155-diy-speakers-subs/2003722-old-school-studio-monitor-build.html)

Carl_Huff 05-17-2015 08:52 PM

Old School Studio Monitor Build
 
3 Attachment(s)
Hello all,

Yes Carl Huff is at it again building monster loudspeaker cabinets from the past. This time I am building a pair of old school large format studio monitors from 30 plus years ago. There are two cabinets gods from that era that are still living among us in the persons of George Augspurger (JBL and Augspurger Consulting fame) and Glen Phoenix (Westlake Audio).

More details can be found for George Augspurger here ...
http://augspurger.com/

https://www.avsforum.com/forum/attach...1&d=1500915021https://www.avsforum.com/forum/attach...1&d=1500915580

and here for Glen Phoenix ...
http://www.westlakeaudio.com/Speaker...ce_series.html

https://www.avsforum.com/forum/attach...7&d=1500915109
]

Carl_Huff 05-17-2015 09:33 PM

3 Attachment(s)
I've decided to build a variation of the classic Augspurger studio monitor. But in my case I will be taking a cue from Glen Phoenix and will be using a Smith horn for the mid to upper bands. The initial system will be 2 way. However I can always add a supertweeter down the road.

The cabinet plans are below ...
https://www.avsforum.com/forum/attach...1&d=1500915761

The dimensions were taken from an actual Augspurger cabinet. The displacement is (approx) 13 cubic feet which happens to be the recommended cabinet size offered up by Parts Express for a pair of Celestion buyout drivers.

I make no claims as to how my cabs will compare to an actual pair of Augspurger monitors. If you want authenticity a pair of Augspurger monitors can be had for $20K. However even if I had that kind of cash lying about (and I don't!) when it comes to loudspeakers I am definitely a DIY guy.

So here is what will go inside my version:
I've got 4 of the 15 inch Celestion buyout woofers from Parts-Express.
http://www.parts-express.com/celesti...8-ohm--299-418

I've got a pair of aging GAUSS 4140 Smith horms. These are only available on the used market and are getting hard to find in good shape. Luckily I've got a decent pair in my stash!

https://www.avsforum.com/forum/attach...1&d=1500915805https://www.avsforum.com/forum/attach...1&d=1500915805

And finally the compression driver. I will most likely slap a Radian 950PB in there http://www.usspeaker.com/radian%20950pb-1.htm

Or if the great god of cash $$ smiles upon me, perhaps a Radian 950 with a berryllium diaphragm loaded http://www.usspeaker.com/radian%20950Bepb-1.htm

_______________
Best Regards,
Carl Huff

Carl_Huff 05-17-2015 09:39 PM

5 Attachment(s)

Carl_Huff 05-17-2015 09:46 PM

2 Attachment(s)
Day 2 ...

https://www.avsforum.com/forum/attach...1&d=1500916193https://www.avsforum.com/forum/attach...1&d=1500916193

Not a bad start. I'd say my 'garage therapy' was worthy of the time spent and I have more to look forward to next weekend.
_____________
Best Regards,
Carl Huff

d_c 05-17-2015 10:10 PM

Nice Carl. It's refreshing to see a different design come along. Tell us more about that horn and what do you have in the plans for the xo?

Carl_Huff 05-17-2015 10:36 PM

Quote:

Originally Posted by d_c (Post 34298538)
Nice Carl. It's refreshing to see a different design come along. Tell us more about that horn and what do you have in the plans for the xo?

Sure,
The GAUSS 4140 was a big deal back in the late 1970's and 80's. Many tour companies used them. They were made in Hollywood, California USA. They take a 2 inch CD, are good down to 800Hz and have 120 degree dispersion. The GAUSS 4140 was inspired by the published work of Bob Smith back 1951. If you Google 'Smith horns' you will find the original article that appeared Audio Engineering. JBL had a very successful Smith horn with their 2397 product. Westlake monitors to this very day use Smith horns in their products.

As to crossover mine will undoubtedly be active. I've got a prototype active crossover with parametric EQ (audiophile Mini DSP???) on my workbench that I will be debugging on this project.
_____________
Best Regards,
Carl Huff

chrapladm 05-17-2015 10:48 PM

Subscribed. Glad to see you at it again Carl. Hope everything else has been going well for you also.

Carl_Huff 05-18-2015 10:05 AM

Quote:

Originally Posted by chrapladm (Post 34299082)
Subscribed. Glad to see you at it again Carl. Hope everything else has been going well for you also.

Thank you for the kind words! It's nice to get back outside doing garage therapy, working on a project that is strictly about relaxation and and having fun.
_____________
Best Regards,
Carl Huff

mobeer4don 05-18-2015 07:09 PM

Nice! Scoring the Celestions will help you justify the beryllium upgrade...;)

chrapladm 05-29-2015 07:14 AM

So how goes it?

PassingInterest 05-29-2015 08:50 AM

Cool project!

LTD02 05-29-2015 10:02 AM

neat project. the pic in post #1 just looks soooo right. :-)


are both woofers run up to the c.d. (2 way) or is the second rolled in only to help with the bass (2.5 way) in your design, and/or the original?

Carl_Huff 05-29-2015 01:00 PM

This last weekend I finished up the woodworking on the first cabinet and got my wife started doing the 'fill, sand, prime, wet sand' cycle. Since these cabinets are large and going into a public space in our home she wanted to go over the top. As result we will be applying an eye catching glossy OSHA Safety Orange paint to them. It was her idea and she wanted to be part of the fun so she volunteered for the 'fill, sand, prime, wet sand' cycle. She's never done this before, but she's working hard at it and doing a good job! I spent my time assembling the 2nd cabinet.

The raised triangle shaped trim pieces that go above and below the drivers were 'futsy' to build. I spent a lot of time making them. I ended up cobbling together a fixture to hold the pieces at the proper angle so they could be ran thru my table saw. It took 5 tries to create 4 pieces but it all worked out in the end.

Real Augspurger monitors use TAD 1603 drivers and CDs. The few real Augspurger monitors that I had a chance to study were all straight 2 way systems with the drivers operated in parallel. I'll bring both drivers out to binding posts. That way I can experiment with a 2.5 setup. I've never tried to build a 2.5 solution but it sounds interesting tho. Have you LTD02? Any thoughts to share??

I have a pair of TAD 1603s in my stash but not 4 of them. The TADs should reach an octave lower that the Celestions in the same cabinet. However that would be of little value if I use subwoofers. The cabinets are cut for the Celestions. I will have to check and see if the TADs bolt up. If they do I probably will swap the drivers back and forth a few times for jollies.

I'll take more PICs this weekend and update our progress.
____________
Best Regards,
Carl Huff

chrapladm 05-29-2015 07:57 PM

Carl have you ever had a ribbon for the highs above a large horn?

I was looking at doing a large bass bin with a large horn. Then I was looking at adding a ribbon for the highs above possibly 6khz and higher above the large horn. Wont be happening anytime soon as the ribbons are expensive and I only want to use the Raal's if I go that route. But I have always been curious on what a supertweeter sounds like.

Carl_Huff 05-29-2015 09:18 PM

Quote:

Originally Posted by chrapladm (Post 34611929)
... But I have always been curious on what a supertweeter sounds like.

About the only supertweeter that I have heard that truly impressed me were the Enigma Sopraninos that are here ...

http://www.enigmacoustics.com/prod-i...le.asp?idno=92

and are reviewed here: http://www.6moons.com/audioreviews/enigma/1.html

They cost stupid money, upwards of $4K per pair. But I admit, if I had the $$ lying about I would be truly tempted to buy a pair.
____________
Best Regards,
Carl Huff

chrapladm 05-29-2015 09:56 PM

Quote:

Originally Posted by Carl_Huff (Post 34613401)
About the only supertweeter that I have heard that truly impressed me were the Enigma Sopraninos that are here ...

http://www.enigmacoustics.com/prod-i...le.asp?idno=92

and are reviewed here: http://www.6moons.com/audioreviews/enigma/1.html

They cost stupid money, upwards of $4K per pair. But I admit, if I had the $$ lying about I would be truly tempted to buy a pair.
____________
Best Regards,
Carl Huff

Hmmmm.....thats probably the same experience I had with the AMT/Raal. Not saying they are exactly the same but for me it was night and day difference on the highs compared to CD's. BUT 4K a pair is a bit step. I thought Raal prices were steep at about 12-1800 a pair.

LTD02 05-30-2015 12:54 AM

1 Attachment(s)
"Any thoughts to share??"

iirc, about the same time jbl was experimenting with the Everest and they settled on a 2.5 way arrangement.

https://www.avsforum.com/forum/attach...1&d=1432968473

the second woofer is rolled in around 100hz.

http://cdn.avsforum.com/e/ed/ed85e92...tach213997.gif


part of the rationale, i suspect, was that they were shooting for smooth power response. with the 2 way, the drivers create some cancellations off axis (-6db somewhere around 500-600hz by my guess) which was a little lower than the capability of the c.d. on the horn. I'm not sure how much that matters if you'll pretty much be on axis most of the time...

LTD02 05-30-2015 01:03 AM

it looks like augspurger is running the 950pb. that should allow a low enough crossover point for smooth power response even in a 2way arrangement.
http://augspurgermonitors.com/gah4k/
http://www.usspeaker.com/radian%20950pb-1.htm

Boomassiv 05-30-2015 09:11 AM

Quote:

Originally Posted by LTD02 (Post 34615513)
"Any thoughts to share??"

iirc, about the same time jbl was experimenting with the Everest and they settled on a 2.5 way arrangement.

https://www.avsforum.com/forum/attach...1&d=1432968473

the second woofer is rolled in around 100hz.

http://cdn.avsforum.com/e/ed/ed85e92...tach213997.gif


part of the rationale, i suspect, was that they were shooting for smooth power response. with the 2 way, the drivers create some cancellations off axis (-6db somewhere around 500-600hz by my guess) which was a little lower than the capability of the c.d. on the horn. I'm not sure how much that matters if you'll pretty much be on axis most of the time...



I love those cabinets. The levels look good but I wonder what it looks like with the UHF removed. I also like the 2.5 idea if you are not using separate subs but see no reason for it otherwise.

Carl_Huff 05-30-2015 09:43 AM

Quote:

Originally Posted by LTD02 (Post 34615617)
it looks like augspurger is running the 950pb. that should allow a low enough crossover point for smooth power response even in a 2way arrangement.
http://augspurgermonitors.com/gah4k/
http://www.usspeaker.com/radian%20950pb-1.htm

Good research on your part, thank you! I had not known that Augspurger had switched CD vendors. By coincidence the Radian 950PB is what I was looking to use in these cabs. I wonder if they are still using TAD 1603s?

The 2.5 solution that you point to is certainly interesting. Not too long ago I setup a customer 2 channel listening space that amounted to a pair of JBL Everest DD66000s with 2 subwoofers. The electronics were a Datasat RS20i w/ Dirac Live thru quality amplifiers (don't remember what they were). That was the first time that I had done a room with that gear combination. Both the owner and I were very, very happy with the results.
___________
Best Regards,
Carl Huff

Nate Hansen 05-30-2015 12:22 PM

Quote:

Originally Posted by Boomassiv (Post 34620769)
I love those cabinets. The levels look good but I wonder what it looks like with the UHF removed. I also like the 2.5 idea if you are not using separate subs but see no reason for it otherwise.

I think the .5 would allow more flexibility in setting up multiple subs.....it doesn't really look like it goes low enough to run on its own and I don't see any reason for that anyways. Also, the .5 would increase headroom down low where power demands are increasing. Depending on how the speakers are setup it could also help with some modal smoothing and SBIR.

I've done some work with large side by side woofers like this and I would think you'd have a hole in the power response due to the increasing directivity of the woofers around 400-500 IIRC if you run them all the way up. Depending on the horn it could be a good match as long as you aren't listening too far off axis, but I don't think this design is really meant for that anyways.

kingpin111 05-30-2015 03:05 PM

Hey Carl. Are you replacing your current setup with these?

antisuck 05-30-2015 04:21 PM

Quote:

Originally Posted by kingpin111 (Post 34627169)
Hey Carl. Are you replacing your current setup with these?

Haven't you heard? Iwata horns are lame, nobody wastes their time with them any more. You should have Tux send me yours, I'll even pay for shipping. Tell him not to bother taking off those clunky compression drivers with the poisonous diaphragms, I'll figure out some way to dispose of them. ;)

AudioJosh 05-30-2015 05:00 PM

I was going to ask about the comparison with Iwata. However, it looks like the Smith horn is more CD like, am I right? It also doesn't load nearly as low. I always wrote off the Smith horn (on sight, haven't heard) as I assumed they were just old skool diffraction horns.

Carl_Huff 05-30-2015 08:29 PM

2 Attachment(s)
I've had these Smith Horns (ie: Gauss 4140s) for several years and never used them. A while back I had the pleasure of spending a long afternoon with Glen Phoenix at Westlake Audio in Newbury Park, California and listened to some of his top of the line loudspeakers. Glen has used his trademark hardwood Smith horns in his Reference Series for the last 30 years. Sure they are lesser tech than newer products, but I often wonder if we can truly hear the nuanced differences that we measure with the latest techniques and then see exaggerated on vendor cutsheets.

https://www.avsforum.com/forum/attach...1&d=1500916415https://www.avsforum.com/forum/attach...1&d=1500916415

To my ears the top of the line Westlake Audio products sound as good as they look.
___________
Best Regards,
Carl Huff

Carl_Huff 05-30-2015 09:03 PM

These loudspeaker will be replacing the IWATAs mounted on JBL theater cabinets that I am currently using. It's not that I've grown tired of the IWATAs. To the contrary they still sound good to my ear! But being the big kid that I am I'm simply ready to play with different toys. Building my interpretation of classic loudspeakers is a hobby for me. I enjoy looking backwards at 'old school' success stories.
____________
Best Regards,
Carl Huff

Tip24/96 05-31-2015 04:13 AM

Quote:

Originally Posted by chrapladm (Post 34613833)
Hmmmm.....thats probably the same experience I had with the AMT/Raal. Not saying they are exactly the same but for me it was night and day difference on the highs compared to CD's. BUT 4K a pair is a bit step. I thought Raal prices were steep at about 12-1800 a pair.

How would you impliment a Raal as a super tweeter over a compression driver considering that the Raal has such low sensitivity compared to any compression driver? Wouldn't that necessitate an active crossover?

chrapladm 05-31-2015 05:08 AM

well after viewing the link Carl posted on the electrostat like tweeter I am thinking it can be done just fine. Cross around 10Khz and let them over lap a bit. BUT I am just throwing ideas out there. And I will first get my setup dialed in after it is built then see if I want to add anything else. Still tossing around some ideas in my head like Carl and his build here.

Tip24/96 05-31-2015 06:27 AM

Quote:

Originally Posted by chrapladm (Post 34638153)
well after viewing the link Carl posted on the electrostat like tweeter I am thinking it can be done just fine. Cross around 10Khz and let them over lap a bit. BUT I am just throwing ideas out there. And I will first get my setup dialed in after it is built then see if I want to add anything else. Still tossing around some ideas in my head like Carl and his build here.

What compression driver and horn would you run?

chrapladm 05-31-2015 06:43 AM

Not sure yet. Everytime Carl posts these great builds I come back to the large horn and supertweeter idea. For me tI have to go where my budget can. SO its what I can find. Dont want to take away more from Carl's thread though.

I hope to see some more progress of his great build.


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