RS 2.5 active crossover replacement

Sadly my original Infinity Active Crossover that has served me faithfully with my RS 2.5's for years (it is visible at the top of the stack in my avatar) gave up the ghost about a week ago and now blows its ½ amp AC fuse as soon as the power switch is turned on. Although I have a great vintage audio repair shop about 20 miles away in San Francisco, not being able to find a schematic for the unit I have some concerns as to the possibility of getting it repaired and so have been looking for a reasonably priced contemporary replacement. In the meantime I am simply passively bi-amping the 2.5's.

The units I am looking at are the Behringer CX2310, the DBX 223S or XS, and the Nady CX22SW and was wondering if anyone has an opinion regarding any or all of them as a suitable replacement or otherwise another manufacturer's unit in the same price range that would be suitable.

I still may take the Infinity crossover up to L&M Electronics, the shop I mentioned previously, to see what advice they have relative to the possibility of repairing the Infinity unit for a rational cost but in the meantime would like to get a suitable replacement that I could just keep as a back up should a repair be feasible, although I know that any contemporary unit I purchase would probably outperform the 30+ year old Infinity.

Thanks in advance for any help and/or advice provided.

Might this do?

http://www.infinity-classics.de/technik/manuals/RS_2.5_technical_sheet.pdf

I use a Bryston 10b Active Crossover with my 2.5s, with superb results. Not inexpensive, but they pop up on the used market reasonably often. Best audio dollars I ever spent.

EchoWars said:

Might this do?

http://www.infinity-classics.de/technik/manuals/RS_2.5_technical_sheet.pdf

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Absolutely.

After seeing your post I went back into the file cabinet drawer that houses all of the manuals and schematics for pretty much everything vintage that I own thinking that there was no way I couldn't not have a copy of that schematic and lo and behold - there it was hidden in plain sight. A major senior moment on my part. Thanks for the link and for jogging my memory.

The device doesn't look very complicated so maybe I'll give L&M a shot at it before I commit to a new crossover. As I said in my original post, I suspect I would get better performance from a modern crossover but I sure do like having that original Infinity component in the mix.

kneeOhFight said:

I use a Bryston 10b Active Crossover with my 2.5s, with superb results. Not inexpensive, but they pop up on the used market reasonably often. Best audio dollars I ever spent.

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I'm afraid the Bryson is way above my acceptable price point for such a device but thanks for the suggestion nonetheless. If I can't get the Infinity E.C.U. repaired locally, which is now once again my first choice thanks to Echowars memory jog, I'll probably go for one of the much less expensive units mentioned in my initial post.

EchoWars said:

Might this do?

http://www.infinity-classics.de/technik/manuals/RS_2.5_technical_sheet.pdf

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I don't trust any of those and wish they would just take them down...I have 3 sets of Infinity speakers and every one of the schems from the classics.de website is wrong in some way...

Bkphoto said:

I don't trust any of those and wish they would just take them down...I have 3 sets of Infinity speakers and every one of the schems from the classics.de website is wrong in some way...

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Having recapped at least six vintage Infinity speaker pairs myself I agree that many of the passive crossover schematics that are available at Infinity Classics have errors and especially inaccurate capacitor values due in large part to Infinity's predisposition to continue tweaking crossovers in their speakers after the initial production run and release of documentation but I'd wager the E.C.U. schematic is close enough to accurate to give the techs at L&M Electronics in San Francisco a good shot at figuring out the problem.

EDIT: I wanted to add that although I haven't been very active on AudioKarma in the last year or so after many years of providing a pretty steady stream of contributions of varying degrees of value, I am once again reminded of what a valuable resource this forum and it's members and contributors truly are.

Bkphoto said:

I don't trust any of those and wish they would just take them down...I have 3 sets of Infinity speakers and every one of the schems from the classics.de website is wrong in some way...

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No way. That site is a hugely valuable resource. So what if some of the values are off due to Infinity making changes on the fly, at least it's close to reality. The diagram on that site of the RSIIb LFEQ box was very helpful to me in understanding how it works, and in tearing it apart and rebuilding it, even though it wasn't exactly equal to my model; same with the crossover - as long as you go in knowing there may be discrepancies, having 95% of the info is way better than having 0%!

not if people don't know what they are doing and instead of replacing what is there they go by that instead...again, I'm 0 for 3

I have to agree with Maxamillion regarding the incredible source of information that the Infinity Classics website has provided over the years.

The first thing I do when approaching the recap of speaker crossovers is check the capacitor values in the physical crossover against the downloaded schematic and order replacement parts accordingly. I also verify the wiring relative to the phasing of each driver in the speaker and make any necessary corrections in my copies of the schematics. In fact I have posted a couple here on AK over the years including this Monitor IIa crossover schematic from a 2013 thread, the original of which contains several errors.



Here's the link to the thread started by loquatious for anyone interested:

http://www.audiokarma.org/forums/attachment.php?attachmentid=430556&d=1368716563

The errors I found leading to the corrections I made in the schematic are in Post#13

I'd much rather start off with something to reference, even if it does contain some errors, than nothing at all.

Work on that link.

Coastsider said:

I'm afraid the Bryson is way above my acceptable price point for such a device but thanks for the suggestion nonetheless. If I can't get the Infinity E.C.U. repaired locally, which is now once again my first choice thanks to Echowars memory jog, I'll probably go for one of the much less expensive units mentioned in my initial post.

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You cannot go wrong taking Echo Wars advice, period.

Link correction and ECU update

EchoWars said:

Work on that link.

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Oops - sorry. Here is the correct link to that thread:

http://www.audiokarma.org/forums/showthread.php?t=520042

And as far as an update on my RS 2.5 ECU, it is now at L&M Electronics in San Francisco for diagnosis and repair. In the meantime I am passively bi-amping my 2.5's.

kneeohfight said:

you cannot go wrong taking echo wars advice, period.

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+1.

Bkphoto said:

I don't trust any of those and wish they would just take them down...I have 3 sets of Infinity speakers and every one of the schems from the classics.de website is wrong in some way...

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This is a thread about 2.5s, right? The 2.5 schematic is 100% accurate.

RS 2.5/4.5 ECU repair update

So the diagnosis at L&M Electronics where I took my Infinity ECU for repair was that the power supply transformer was shorted but that it was unrepairable because they were unable to source the part. Disappointing news at best.

I finally got around to picking it up this week and not being the type of person that supposes that while a relatively simple transformer as is used in this crossover based on a cursory look at the schematic might not be available from it's original manufacturer 40+ years after the fact, a reasonable replacement might be found that would do the job. So I popped the lid and found the manufacturer's name and part number clearly marked on the body of the transformer which it turns out is a Dale PL-23-09. Very little research on-line determined that it is indeed still being manufactured by Vishay and furthermore that it is available at Mouser although in a minimum order quantity which was way more than I needed and with a 13-16 week lead time. These facts initially gave me pause but factoring in what it would have probably cost me beyond the $50 diagnostic fee if L&M would have completed the repair and feeling confident that they did indeed isolate the problem given what work I observed had been done on the power supply board, and also feeling confident that I am fully capable of replacing the transformer myself when the parts arrive sometime in late May, I went ahead and ordered the required dozen pieces.

So if anyone owns one of these fairly rare specialty items that Infinity provided with the RS 4.5 and made available as an option with the RS 2.5 and would like to have the comfort of knowing that they have a spare power supply transformer for that item just in case disaster should strike at some point in the future, drop me a PM around the end of May as I will probably be interested in divesting myself of the surplus pieces at cost which is actually pretty minimal per each.

Perhaps now is the time to tell you that 'a bad transformer' is too often tech code for 'I have no idea what's wrong with this thing', or 'I'm too incompetent to troubleshoot this and I really don't want to fool with it'.

Honestly, transformers are the most reliable part in just about every electronics piece out there. Any time some tech tells you 'it needs a transformer', red flags should go up.

EchoWars said:

Perhaps now is the time to tell you that 'a bad transformer' is too often tech code for 'I have no idea what's wrong with this thing', or 'I'm too incompetent to troubleshoot this and I really don't want to fool with it'.

Honestly, transformers are the most reliable part in just about every electronics piece out there. Any time some tech tells you 'it needs a transformer', red flags should go up.

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I certainly respect your expertise in such things but since the fuses were instantly lighting up when power was applied and there is so little to the power supply in this thing besides the transformer - just a bridge rectifier, a couple of resistors, some caps, and what look to be a couple of voltage regulators, and given that they isolated the power supply board from the main board and pulled legs and checked most of the discrete components on it along with the fact that there is some varnish bleeding around the transformer, I'm just going to have to assume they weren't shining me on. I've been taking vintage gear to this shop for years and they've always been pretty straight up with me so I'll be surprised and pretty pissed if they were just yanking my chain on this one but I guess I'll have to wait until May to find out.

Coastsider said:

I certainly respect your expertise in such things but since the fuses were instantly lighting up when power was applied and there is so little to the power supply in this thing besides the transformer - just a bridge rectifier, a couple of resistors, some caps, and what look to be a couple of voltage regulators, and given that they isolated the power supply board from the main board and pulled legs and checked most of the discrete components on it along with the fact that there is some varnish bleeding around the transformer, I'm just going to have to assume they weren't shining me on. I've been taking vintage gear to this shop for years and they've always been pretty straight up with me so I'll be surprised and pretty pissed if they were just yanking my chain on this one but I guess I'll have to wait until May to find out.

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Sounds like a bad power transformer to me.

Alrighty then.

Like I said though, any time a tech says 'bad transformer', more than a modicum of proof is required. If you feel he's met that standard, then there ya go.