Capacitors...

[Ian Mackenzie]

Hi MJC,

Nice post. There is a lot to be said for looking outside the square sometimes.

The L212 is one of my favourite JBL vintage consumer systems.

Ian

[X_X]

Thanks to Widget for his suggestions- I am experiencing the best I have ever heard (in my own home).

Clark,

You might be delighted to know- the 4345's still sound like 4345's even with active electronics. Actives like the DEQX tighten it all up, time align everything, and bring the muscles of the 45's into the current sota. Room correction is an added bonus.

Nate.

[X_X]

The DEQX has been around a while now.

I first alerted The Widget and others to the DEQX some years now in previous version of the forums.

Not only has the DEQX been around for a while now, so has the 4345. I can't speak of the early versions, but I certainly like the latest software.

However, I don't genuinely consider tampering in such a manner with a classic JBL design anything more than an other morph'd pseudo diy system.

Oh come on Ian! really?
You should quickly alert the others about this! I am stunned that so many people here are enjoying "morph'd pseudo diy systems" that you helped them build!!!

Glad it worked out for you though. G.T recommendations posted elsewhere more or less sum up the mods for the 4345.

I tried Greg's recommendations all the way- I still am. Why would he ever suggest going active on the 4345? I mean, let's see- he suggested biamping to isolate the 2245's because they don't respond well to passive components. Then he suggested powering the 2405 actively for the same reasons. Hmmm... that's an active 3 way isn’t it? Gee, that's what a DEQX is. Amazing...

I thought about that route too but considering all the drivers are 20+ year old designs and then there is that much dated horn, compression driver and UHF driver I could not see the "sense" in that kind of expenditure and complexity on anything other than the lastest JBL SOA drivers. For the same outlay I prefer to own and variety of "well" designed vintage and comtemporary loudspeaker systems.

Hey mate, because the drivers are 20+ years old makes it all the more reason to bring them into focus by going active. I wish you could hear this.

The 2245/2122 is the best thing about the 4345 IMO. You and I have talked a lot in PM’s about the horn and the 2405. Try a Raven R1 for the UHF- very nice. Let the 2405 plug the hole. I can’t get around the foghorn yet, but I’m thinking of a way. I might have a go at building a set of cabs to house only the 2245/2122 then have some fun.

Clark's upgrades by the way did not cost him hardly a dime.

He is such a humble nice guy and so passionate it would not have been right.

The price of the 4345 makes doing much else a strain on the budget. The DEQX wasn’t pocket change to me- it cost a lot by my standards. If changing out caps and bypassing makes a marked improvement, than how can anyone find fault with that? I can’t. After trying things one way- I try them a new way. I’m never settled on having it the same for too long. I feel compelled to make improvements…

Ian- Just curious, what value did you use for the ULF cap when you went full passive?

[MJC]

After trying things one way- I try them a new way. I’m never settled on having it the same for too long. I feel compelled to make improvements…

At some point in time you get as high as you can with a particular system.
I can't imagine L212s sounding any better than using a CC network. Are there better speakers, sure there are.
My experience using a solen based CC network is pushing me to build CC networks for my PT800s, which are better than the L212...but there is something about playing vinyl thru CC L212s and vintage '70's amps.

[Ducatista47]

I am sure the DEQX is a fine piece of gear, but even if it were free I would have no personal interest in it at this time.

I have put together gear that has a very detailed, delicate, natural output to the speakers/headphones. A minimalist analog path through outstanding gear has brought me to this point, and I have no intention of inserting an a/d - d/a piece into the chain. I think when information this clear and true is coming through, that could only degrade the signal, whatever the other benefits. That is just not what I am about as a listener.

I am still very grateful for the suggestion! If one ever falls out of the sky I may give it a listen, but not on the rig I am using now.

Clark

[Ian Mackenzie]

Possibly something that is taken for granted is capacitor value tolerance.

Close to spec is important but matching between channels even more so.

[MJC]

I have put together gear that has a very detailed, delicate, natural output to the speakers/headphones. A minimalist analog path through outstanding gear has brought me to this point, and I have no intention of inserting an a/d - d/a piece into the chain. I think when information this clear and true is coming through, that could only degrade the signal, whatever the other benefits. That is just not what I am about as a listener.
Clark

I, for one, understand that thought process. I use a Citation pre-amp and power amp to run my CC L212 with a turntable as its only source. Sweet.
I could probably use a better turntable, tho.

[Ian Mackenzie]

I agree. There is alot to be said for keeping it simple.

While not wanting to join bashing digital processing debate here you are either in one camp or the other ultimately.

While I fully appreciate the theoretical wisdom of fully active setups it is seldom done correctly (quite right) in terms of re engineering the original passive voltage drives and as mentioned then there is all the additional stages the signal goes through.

I often wonder is the active guru hearing the modified response of the active implementation or the control over the drivers?

All the fully active results I've heard in either the digital domain or analgue with one exception is that of a fairly hard sterile sound like the original signal had been processed through a road re surfacing machine. Lynn Olsen wrote about this recently on diyaiudio.com

Without very sophisticated measuring equipment on hand I would question the value of a true fully active setup. They can take months to dial in.

I would rather spend that time enjoying other pursuits.

Granted if you want to experiment with time domain or horn equalisation the results can be interesting but a DEQX is only a tool and is only as good as the skill of the user. Typically a loudspeaker designer uses an active filter set to quickly assess the intended passive voltage drivers during development of a passive crossover network. (I can do all that myself with Soundeasy..if I wanted to and if had the time..look out for an advert in the marletplace)

Therein lies an issue with actively driving compression drivers and tweeters. To protect the delicate devices a capacitor is highly recommended in series with the drivers. To do so without is very risky.

So you are back to square one and this capacitor needs to be a large one so as not to effect the phase or transfer function of the active system. Some systems like the JBL 4435 use this capacitor as one pole of the resulting high pass filter when biamping. Clever.

Thus, on the previso that it ain't broken then don't attempt to fix it. In most cases (a sensibly engineered domestic system) 90% of the benefit can to gleened from simply biamping.

Back the mininalist audio system theory. This is where I think it makes most sense to use a carefully thought out capacitor selection.

Late at night I plug my variable output Lavry Dac directly into the Pass Labs power amp and play my favourite Cd's with simple 2 way dynamic loudspeaker (no names..a Lynn Olsen favorite).

There is only one capacitor in the signal path.......

[merlin]

I agree. There is alot to be said for keeping it simple.

While not wanting to join bashing digital processing debate here you are either in one camp or the other ulimately.

Ultimately I'm in the analogue camp. I'm currently playing with the DEQX on some two ways and it's a fun piece of kit that makes getting good results relatively easy, rather like painting by numbers. But just as painting by numbers will never produce a great work of art, the DEQX will never make the hairs stand up on the back of my neck. It seems in some ways to act as a smoothing filter, in much the same way as the Tact RCS does - only to a lesser degree to my ears. The tiny little inflections and micro details/dynamics that make us believe things are real are missing with DEQX - good as it is in so many areas.

I was going to send mine off to Tom Evans to have it modified, but I now think I will use it short term and then sell it on once I have a decent analogue alternative in place. Don't get me wrong, the DEQX is a very impresive box of tricks and can blow the sock off most people. You would need a substantial investment in analogue electronics to get to the stage where it is shown up. But once you've been there, it's difficult to go back.

[Ian Mackenzie]

Hi Merlin,

Nice to read an alternative view from another DEQX user.

That raises an interesting point..the conflict of trying to get it right and the significant analogue investment....

A JBL without goose bumbs is not a JBL in my book.


Back to my kitchen table....

[Ian Mackenzie]

Quote:
However, I don't genuinely consider tampering in such a manner with a classic JBL design anything more than an other morph'd pseudo diy system.
""Oh come on Ian! really?
You should quickly alert the others about this! I am stunned that so many people here are enjoying "morph'd pseudo diy systems" that you helped them build!!!""

My only reason for following up on this point is everything here gets googled soon or later and I hate being misquoted.

For Natés benefit and other newer members a while back we went to great lengths to draw or make the distinction b/n diy and technical help/references. This was because all the diy and techncial (JBL) stuff was being crossed up in all sorts of threads to the point of it becoming one big noise where references to specific JBL designs and other vital technical information was becoming blurred with misinformation and non tested/ diy iterations that were plain incorrect or crazy.

Essentially technical discussions / tech help and restoration information/ data is posted in the Technical Help forums. In the diy forums "here" basically anything goes unfortunatety because its got to the stage where we neither have the time nor the inclination and to track and monitor every thread.

I am certain of that distinction with my posts. I do however spent more time than I should helping newer members stay on the rails in certain facets the diy forums.