Paging Dr. Frankenstein - Monster System on a Budget

[miscrms00]

Paging Dr. Frankenstein - Monster JBL System (Monstrosity?) on a Budget

So as I mentioned in my intro thread, I somewhat accidentally have fallen back into the audio world in kind of ridiculously ambitious way. I was at a local college auction minding my own business, and next thing I knew I had a U-haul full of vintage JBL and Altec theater gear.

Well, after much reading and thinking and trading and soldering and listening and selling and marital stress, here's the preliminary plan that I've arrived at:

Budget: $0

Use: Multipurpose home theater, casual listening, gaming, critical(ish) listening system for jazz, classical, hip hop, folk, metal, rock, pop, classic rock, blues, world, punk, EDM, action, drama, comedy, art film, classics, cartoons, tv shows, sci-fi, etc.

Room: Finished basement, roughly 16x32' (?need to measure) open space, back half used for HT. Front half is all Legos, all the time.

Goal: Assemble the best sounding vintage(ish) system with modern compatibility possible within my budget while having as much fun building / tweaking / repairing as possible.

Based on the equipment I now have on hand (or ordered / enroute) here's what I'm thinking currently:

Any thoughts, concerns, encouragement, admonitions, etc welcome. :scratch2:

Rob

 

[dread31]

$0? Holy crap!!!!!!!!!!

 

[miscrms00]

Yeah, I got pretty lucky at the auction. As hard as it was to let them go I was able to sell the Altec speakers (288C CDs, 515B woofers in 816A cabs) for enough that I think the buyer still got a good deal and I made a small net gain, enough to purchase the Sherbourn and second JBL 5235 active crossover. After repairing the Altec 9440A (mostly just supply caps) I was able to trade it for the cosmetically rough but re-tubed and functional MA-230. The UREI crossover and Intellabeam were traded for the Denon CD and an Elac 50H turntable. The TV and older projector I already had, and the HK was sitting in the closet with a failed input board. Was able to remove the upper boards and repair a power supply issue to get the 5 power amps back up and running. The S38s have been my front pair for many years, picked up through a friend at an employees only sale along with the AVR-7000 many years ago.

Having way more fun than I should be

Rob

 

[miscrms00]

Getting ready to button the Harman Kardon AVR-7000 back up. Ready for multi-channel testing when the PT-7030 arrives tomorrow.

Always loved this amp, at 49lbs, 17.3"x20.4"x7.6" she's a monster and a beauty. Can't believe those supply rails. Claimed to be able to put out 75A instantaneous current. Could probably weld with it Maybe one of the last great HKs?

Built 2001, shelved with "Protection Mode" failure in around 2010? Had tried to repair previously, seemed like a failure in either the power supply or pre-amp board, but it had seemed like the power amps were still alive. In re-soldering some of the supply caps, I had incorrectly connected a "floating" resistor that did not appear in the service manual schematics and smoked it. Gave up on it at that point.

Replaced it with an AVR-3600, which was ok but definitely not of the same caliber. Having HDMI was pretty much a necessity at that point though. The 3600 only lasted 3 yrs unfortunately.

In need of amp channels for this new setup, I was inspired to give it another go. Tore it all down again (quite a job in of itself), and removed the offending resistor all together. Powered it up with only the main board in place, all seemed well. Added the pre-board back in, and protect mode. Removed the backplane connectors, de-powering the board, and all was well again, and the with passive pass through from the main-in jacks to the power amps in place I was able to confirm that all 5 channels worth of power amps are sounding fine. Put 3-4 hrs of time on it, no signs of excessive heat or trouble.

May eventually replace with something like JBL 6230/6260s, but nice to have it back in the mean time!

 

[miscrms00]

Current Build Status:

UREI 539 EQs are currently standing in for preamps after JBL crossover. MA-230 with temporary main in tap driving horns, P-2200 driving the bass bins. Have tested the smaller LF/HF units for the center with the second JBL crossover. Its all sounding really promising!

With the PT-7030 arriving today I should be ready to test multi-channel with digital input and real pre-amp to put proper levels to the crossovers and power amps!

 

[SX550]

those are some horns :O

 

[miscrms00]

They're not exactly small

By comparison I do find them to have a less harsh sound than the smaller FF horn on the same large format driver. The big horns are in the 2360A family, I think they are technically 2365As with a 60x40 degree pattern rather than the 90x40 pattern of the 2360As. The smaller horn is a 2380A, I think its a 2386A with a 40x20 degree pattern. Not ideal, but should be much easier to physically fit in the center position. Might try to find a wider throw version of that one.

Driving each with the correct JBL EQ card (now that I have them) does help tame them, and they seem to blend together pretty well.

Rob

 

[miscrms00]

Got the PT-7030 up and running with 2 channels last night, huge difference in SNR compared to my cobbled together solution with the EQs! Hopefully will get to run multi-channel this weekend. Need to order materials to make up proper cables. Thinking of using this bulk microphone cable from monoprice all around. Seems like using a 2 conductor wire with shielding is a good idea even for the unbalanced connections, rather than having the return on the braid.

http://www.monoprice.com/product?p_id=5978

 

[blazeaglory]

wtf?? thats insane!

 

[Rome]

Lots of sound in there!

Rome

 

[J English]

You're going to need some earplugs when that's done, I think. You've got enough power there for a music club. Well, good scores anyway!

 

[SuperLead100]

What?

 

[miscrms00]

Thought I had posted this earlier, but completed my first full multi-channel test this past weekend! Did a quick leveling by ear using the test tones to each channel from the PT7030, then watched the first Hobbit Bluray with the family on a futon mattress in the garage. Very pleased with the results so far, just need to figure out how to arrange it all in the basement now in such a way as to keep toddler fingers out

The TV is an NEC 50" plasma monitor if that helps with sense of scale

Rob

 

[toxcrusadr]

You're gonna need a bigger TV.

Apologies to Jaws...

 

[miscrms00]

Here's the plan so far in Sketchup:

Planning to use the Ikea Besta system to organize things. Cubes will have black doors with smoked glass to keep little finger out. I may also try using the Kallax series caster to put both units up on wheels, for rear access. Ordered a set of Middle Atlantic 27U rack rails from Amazon to convert the left unit into a rack. Also ordered an ART PS4X4 PDU with analog meters, and an AC Infinity thermal controller with 2 sets of 2 fans. Not sure yet if I'll need both in the rack (top exhausting and bottom intake maybe?) or if one set will be enough, in which case I'll plan to use the other set on the left most cube under the TV where most of the sources will be on shelves. When I sort out a pre-amp for it (probably just the MA-230 frontend for starters) the turntable (Elac 50H) will likely go up on top of the left rack. Will need to come up with grill covers for the woofers too at some point, planning to stick the ones off the servo-drive over the 4648As for now. Also need to work up some mounting brackets for the horns so they don't kill anybody.

Probably a little over budget at the moment, but negotiating on the sale of the last few JBL horns which should put things back on track

Rob

 

[ronscat]

You win - super system!!

 

[slow_jazz]

Amazing setup.

 

[miscrms00]

Status update:

Making progress on the MA-230. Had a failed cap in the voltage doubler resulting in low plate voltage on the output tubes and hum/noise. Replaced caps getting the full output voltage back only to discover I had a weak output tube (fairly new JJ). Replaced with Tung Sols, back in action.
http://www.audiokarma.org/forums/showthread.php?t=678229

Just about finished building the "custom" equipment rack using Ikea Besta components. Built up the sides with strips of spare shelves from the AS IS section to get the spacing right on the Middle Atlantic 27U rails. Drilled out the holes on a set of Kallax casters allowing them to bolt right into the foot holes on the Besta unit. Found a second 2x1 Besta unit in the AS IS section, cut down and attached to the back to extend depth from ~16" to ~23". This is just for containment not load bearing, though its fairly stable as it rests on the rear caster plate overhang. Mounted AC Infinity dual fan unit at top rear to draw air up through the rack and exhaust. This should leave enough room for something (possibly the MA-230 or a turntable) to sit on the top front without blocking.

Also found a set of JBL 8330 Pro Cinema Surrounds local for cheap on CL. These should be much easier to mount than the S38s.

Should be almost ready to start assembling the system in the basement. Just need to come up with a mount for the horns.

Also picked up an older Sony VW40 projector for cheapish at a local pawn shop through ebay. Still keeping my eyes open for a deal on a JVC, but this is still a big step up from the Infocus X1 Also need to find a better screen at some point. The one I have is nice, draper access/v recessed powered tab-tensioned, but its 84" 4:3 which is certainly not ideal.

Now I really need to get some more stuff sold to get back on budget

Rob

 

[miscrms00]

So, I guess I should have built a bigger rack

Test fit, and I'm already running out of room Biggest change is I ended up testing the two Altec 1608A mixer / power amplifiers that I had from the original haul and really liking the one that was working. Ended up fixing the second one (burned resistors and failed output transistors) and am going to try them on the surrounds most likely, though I may see how them sound on the center HF/LF. They are a lot bigger than the one JBL 6230/60 I was thinking would take on that function though I did find a working 6260 as well, so the HK7000 will be coming out.

Now that I've seen everything in there I'll probably take it all back out and re-order. Trying to compromise between low center of gravity for stability, stacking depths for airflow, and keeping the right stuff (meters / IR sensors) in the windows of the front doors.

Updated diagram:

Rob

 

[Superscoper]

That's freaking awesome. Love the thifty build mantra.