DBX RTA-1 - repair and restoration

[Timbered]

no, no source, but see what you can do w an48

I will inquire about source for that

another rta1 owner and expert has gotten plotting done using excel and wrote me

What I did find was two good tutorials on YouTube, one showing how to graph one set of data and the other showing how to graph two sets of date. Links below [[your task would be to get them to do the diff / normalization functions, which is one of the cooler things about the rta1]]

Hi, Mr. Noon,
I'm the original design engineer of the RTA-1. I ran across your post here as I was preparing to move from the house I've lived in since 1985, when I was still working at dbx.
It so happens that I have the components of an RTA-1, though it is not in working condition. I've been trying to locate some of my former colleagues who still may want these parts. It would be a shame if they ended up as trash, if anyone can still put them to good use.
I noticed one of your posts mentioned someone who is still maintaining RTA-1s. I think I know who that is but I don't know how to get in touch. Can you pass along the contact information for that person? If you doubt my bona fides, you can pass along my name (below) and I'm sure he'll remember me.
If that doesn't work out for some reason, I can at least offer you the key caps you're missing!

By the way, you're right about the pink noise filter. I wrote a little in-house white paper on that -- we wanted to get the worst-case error in the pink noise curve down below +/- 1 LSB of the D/A converter.
- Don B.

Hi Don!

Thanks for weighing in, and the description of your excellent design work.

Did you find a home for the parts you mentioned you had?

Ray

 

[audioC]

Hi, Mr. Noon,
I'm the original design engineer of the RTA-1. I ran across your post here as I was preparing to move from the house I've lived in since 1985, when I was still working at dbx.
It so happens that I have the components of an RTA-1, though it is not in working condition. I've been trying to locate some of my former colleagues who still may want these parts. It would be a shame if they ended up as trash, if anyone can still put them to good use.
I noticed one of your posts mentioned someone who is still maintaining RTA-1s. I think I know who that is but I don't know how to get in touch. Can you pass along the contact information for that person? If you doubt my bona fides, you can pass along my name (below) and I'm sure he'll remember me.
If that doesn't work out for some reason, I can at least offer you the key caps you're missing!

By the way, you're right about the pink noise filter. I wrote a little in-house white paper on that -- we wanted to get the worst-case error in the pink noise curve down below +/- 1 LSB of the D/A converter.
- Don B.

Hello Don ! (thanks to Noon for the uploads)
>>> I'm curious if you still have parts <<<
I've worked on RTA-1's for a mix engineer who owns two, using them on the road with national (well known) acts since they came out.
As you could imagine, these need service every time they come in - currently the "A-rig" unit is not coming up (I'll see in a couple weeks what happened)
He relies on them quite a bit and still says there is STILL no equal on the market in 2024.
I've even made 24bit/192kHz recordings of the stereo pink noise just in case they finally die.

 

[david moran]

Hello and thanks for the welcome.

No, my last name starts with a B and ends with an r. I am trying to think of any dbx engineer from my era whose name started with K but I'm coming up empty. Memory is shaky after 34+ years. Sadly I didn't stay in touch with my old colleagues from the dbx days.

D___ B___ is / was a terrifically sensible engineer and his db-ex colleagues recall him specifically and fondly. He and I worked on good quicky documentation together and then a successor friend of mine and he produced more elaborate use-case documentation. His RTA1 is just a tremendously useful and reliable piece of measurement gear --- 25y after its intro it was still being used by at least two superior speaker designers if only for being so quick and reliable as to xover measurement iterations. Roy Allison said It's a dinosaur, but just so fast and dependable. I used and use it still for measuring loudspeakers (radpat) outdoors. The Michael Jackson tour bought a dozen or so and Entertainment Tonight once closed their segment on his latest tour w closeups of RTA1s driving a bank of EGA monitors in color .

Anyway, anyone who needs to know more about how to use and where to find a tech still willing to discuss (maybe), lemme know, [email protected]

 

[NOON]

Finally got some free time to play around with this properly! PSU that came with it was toast. Bodged an AT power supply direct to the motherboard, tracked down and replaced the shorted tantalum that is typical on these old motherboards.
It then booted right up! Fortunately a previous owner has replaced the graphics card with a VGA compatible model and my LCD is happy to work with it.
Ordered an ATX breakout board and added a -5v regulator, then attached a little ATX power supply. Mostly working as expected, although the pink noise looks a bit rough. I'll leave it on for a while to let the electrolytics reform and see how it goes. I don't fancy doing a full recap, there's hundreds of them!

 

[NOON]

Already settling down nicely!
Has anyone managed to produce any software updates for modern OS yet?

 

[NOON]

Also, mine has V1.5 ROMs which I believe are the latest, but doesn't have the RT60 ROM. Is this available anywhere?

 

[david moran]

View attachment 141494
Finally got some free time to play around with this properly! PSU that came with it was toast. Bodged an AT power supply direct to the motherboard, tracked down and replaced the shorted tantalum that is typical on these old motherboards.
It then booted right up! Fortunately a previous owner has replaced the graphics card with a VGA compatible model and my LCD is happy to work with it.
Ordered an ATX breakout board and added a -5v regulator, then attached a little ATX power supply. Mostly working as expected, although the pink noise looks a bit rough. I'll leave it on for a while to let the electrolytics reform and see how it goes. I don't fancy doing a full recap, there's hundreds of them!

I believe that the memory functions (digital video data) will not work due to the VGA card (analog video data). ... If the memory functions *do* work, please post the make and model of that video card so everyone can search for a couple.

 

[NOON]

I believe that the memory functions (digital video data) will not work due to the VGA card (analog video data). ... If the memory functions *do* work, please post the make and model of that video card so everyone can search for a couple.

Haven't tried saving anything yet, I'll give it a spin later today. It's a combo EGA/VGA card with both outputs and a set of DIP switches for options.

 

[NOON]

Seems to be able to remember curves OK and overlay them on the live display. Closest match I could find for the graphics card is a Video 7 Vega VGA / EGA
I see one of the EGA connector only versions on German ebay for 150 euros!