Well, you know I've been on this site for a while and I've had an end game in mind for my stereo system. These days I find myself convalescing to some degree, so things are pretty slow around my house, so I got the time and all the hardware. This project is based on what I think would be the best diy system to play with building active speakers and have the most flexibility when tuning a multichannel active speaker system while still having a way to easily switch back to an everyday system that can run a fully passive system for everyday listening that doesn't consume as much energy.
Recently I was able to horse trade for a dbx 4820, well I don't need to tell you that this is just what I was hoping to base this entire system around. It has direct balanced digital inputs, room correction, a multitude of features for sound contouring and measuring. I guess I could have gone the minindsp way or deqx but these solutions just don't seen as interactive and I just wanted to take another approach.
The only problem with the 4820 is there is no easy and cost effective solution to controlling all the 4820's channels volume simultaneously. It needs to be good quality. What I really need is a serious 6 channel preamp that also has a feature to run a separate amp and speaker system for everyday listening. I scoured that net for something suitable and came up with the Thule PR350. This is a really decent analog preamp, looking a bit more into it reveals that it has a completely seperate digital and analog sections and the seperation between the circuits (for the most part) it controlled by mechanical relays. That sounds like it would be super simple to modify into exactly what I need.
So the features on this preamp that I will use are the direct 6 channel RCA input to control volume on all 6 mono amps powering the active speaker setup and then the preamp also has a feature to have a separate direct XLR in to XLR out with simple buffer and volume to control the passive setup. The opamps are mostly OPA2134. These are excellent quality opamps. The volume control is handled by several lm1972 ic based volume control chips. These are excellent volume control ic's and are still in production today and seen in some seriously high end gear.
So you see how this project is going to play out, I'm not really sure anyone else is going to be interested but for the curious I will post my progress on this thread. The first step is repairing the Thule, it has some blown opamps but the control circuit is in great shape. I've used this preamps direct XLR feature for many years. It is a really high quality direct volume control. The circuit for this feature even has it's own little, highly regulated power supply. It's a beautiful preamp.
Another thing I'm going to do is post lots of nudes of the 4820. I've scoured the net and can't find any and I don't know about you but I love looking at nude photos of gear and I hope this helps others on their quest by making these available.
Recently I was able to horse trade for a dbx 4820, well I don't need to tell you that this is just what I was hoping to base this entire system around. It has direct balanced digital inputs, room correction, a multitude of features for sound contouring and measuring. I guess I could have gone the minindsp way or deqx but these solutions just don't seen as interactive and I just wanted to take another approach.
The only problem with the 4820 is there is no easy and cost effective solution to controlling all the 4820's channels volume simultaneously. It needs to be good quality. What I really need is a serious 6 channel preamp that also has a feature to run a separate amp and speaker system for everyday listening. I scoured that net for something suitable and came up with the Thule PR350. This is a really decent analog preamp, looking a bit more into it reveals that it has a completely seperate digital and analog sections and the seperation between the circuits (for the most part) it controlled by mechanical relays. That sounds like it would be super simple to modify into exactly what I need.
So the features on this preamp that I will use are the direct 6 channel RCA input to control volume on all 6 mono amps powering the active speaker setup and then the preamp also has a feature to have a separate direct XLR in to XLR out with simple buffer and volume to control the passive setup. The opamps are mostly OPA2134. These are excellent quality opamps. The volume control is handled by several lm1972 ic based volume control chips. These are excellent volume control ic's and are still in production today and seen in some seriously high end gear.
So you see how this project is going to play out, I'm not really sure anyone else is going to be interested but for the curious I will post my progress on this thread. The first step is repairing the Thule, it has some blown opamps but the control circuit is in great shape. I've used this preamps direct XLR feature for many years. It is a really high quality direct volume control. The circuit for this feature even has it's own little, highly regulated power supply. It's a beautiful preamp.
Another thing I'm going to do is post lots of nudes of the 4820. I've scoured the net and can't find any and I don't know about you but I love looking at nude photos of gear and I hope this helps others on their quest by making these available.
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Hi,
You already made some choices (and have particular needs) so it's too late but:
https://spl.audio/en/spl-produkt/volume-8/
What do you consider as room correction? Cause except for eq, loudspeaker management system doesn't include any room correction.
Anyway i'll take a look at what you'll do with it. Dbx4800 is a good unit which sound nice.
You already made some choices (and have particular needs) so it's too late but:
https://spl.audio/en/spl-produkt/volume-8/
What do you consider as room correction? Cause except for eq, loudspeaker management system doesn't include any room correction.
Anyway i'll take a look at what you'll do with it. Dbx4800 is a good unit which sound nice.
I've looked at the spl line of volume controls and for what I need they kinda break the bank for me, plus I got all this stuff hanging around my back room just dying to be put into action. The 4820 has room analysis and correction features not only in the frequency domain but also in the time domain. So by plugging a RTA mic into the front you can do a sweep and allow the unit to set your parameters for frequency and time according to the desired result. I was very blessed to get a 4820, honestly I would have preferred a 4800 with the physical user interface but the 4820 works exactly the same but it is programmed from your computer instead.
The dbx 4820 has some amazing software and hardware in it and its DAC really is second to none to my ears, the clarity with vocals and the overall rightness of the sound just enthralls me. I am really very excited about this project. I'm also going to replace the switching supply in the 4820 with a linear supply. I've already ordered the parts and it just needs to go all together.
Don't expect this to happen in a week or two. I'm pretty restricted in what I can do but if I take my time and go slow I see no reason why this couldn't be accomplished over the next few months.
First order of business is repairing the Thule, it's been broken since I got it, although I've just never needed the features that were broken so never bothered repairing it. Now I have a purpose for it!
The dbx 4820 has some amazing software and hardware in it and its DAC really is second to none to my ears, the clarity with vocals and the overall rightness of the sound just enthralls me. I am really very excited about this project. I'm also going to replace the switching supply in the 4820 with a linear supply. I've already ordered the parts and it just needs to go all together.
Don't expect this to happen in a week or two. I'm pretty restricted in what I can do but if I take my time and go slow I see no reason why this couldn't be accomplished over the next few months.
First order of business is repairing the Thule, it's been broken since I got it, although I've just never needed the features that were broken so never bothered repairing it. Now I have a purpose for it!
in case any are wondering about the Acurus equipment in the photo these are the posts of my rebuilds of an Acurus RL-11 and A-150.
https://www.diyaudio.com/community/threads/acurus-a150-rebuild.355971/
https://www.diyaudio.com/community/threads/acurus-rl-11-rebuild.377026/#post-6785830
I was always surprised that no one ever commented on my a150 rebuild. That is such a popular amp to rebuild and as far as rebuilds and upgrades go I think I took it about as far as you can go!
anyways that is probably what will be powering the passive side of my project mentioned above
https://www.diyaudio.com/community/threads/acurus-a150-rebuild.355971/
https://www.diyaudio.com/community/threads/acurus-rl-11-rebuild.377026/#post-6785830
I was always surprised that no one ever commented on my a150 rebuild. That is such a popular amp to rebuild and as far as rebuilds and upgrades go I think I took it about as far as you can go!
anyways that is probably what will be powering the passive side of my project mentioned above
Well, i've used the 4800 extensively either for live soundsystem and at home ( for a short time as i ended up buying some other product) and there wasn't anything room correction related. Maybe there was software update since but i doubt as the processor didn't have enough 'power' to run FIR.
Maybe you mix delay functionality and eq with FIR ( which are the only way to differentiate between time and frequency domain)?
Anyway it doesn't matter, the unit sound good and it's stable in use: it's a great tool and i must say it was tempting to keep it when i tested it. Another opportunity appeared so i skiped it.
No display is not a bad thing: once setup you won't want to mess with it and light emited can be bothersome in darkness imho.
May i ask why you want to discard original psu for a linear one?
For volume control it's nice you already have a plan to bring back to life an existing unit. I will follow your progress with interest.
Thanks for your input, maybe I was using the term "room correction" a bit too loosely. My plan is to use the auto eq wizard and the real time analysis features teamed with the delay features available and I'm pretty sure I can dial it in as close as my minidsp gets it.
and as for the power supply, I just wanted to give the unit a nice brush up. I think it would be interesting to see what differences could be heard. put it this way... I got way too much time on my hands right now and this is kinda a dream project for me. I just want to take the whole thing as far as I can go for as little money possible IE: use up a bunch of stuff I've collected through the years for something really awesome.
and as for the power supply, I just wanted to give the unit a nice brush up. I think it would be interesting to see what differences could be heard. put it this way... I got way too much time on my hands right now and this is kinda a dream project for me. I just want to take the whole thing as far as I can go for as little money possible IE: use up a bunch of stuff I've collected through the years for something really awesome.
