Small amp for 2405?

[Doc Mark]

Greetings, All,

I've been considering amplification for the 4-way, active, system I've been wanting to setup, and would appreciate some suggestions for a small (10-15W) amp for the 2405's. The drivers are 2245, 2123, 2445, and 2405, and the amps will be Crown CD-300A's (bridged) for each 2245, H/K 870 for 2123, internal amp from H/K AVR 20 for 2445, and the only smaller amp I have on hand is a 45W Nikko integrated set, on which the high end sounds brittle, edgy, and shrill, at least to my ears. I've also given thought to running the 2445 and 2405 with the same amp, and regular crossover, and just going active on the bottom and mid drivers. But, I would prefer to keep the entire system active, if possible, so your suggestions for a decent small amp for the 2405's would be appreciated. Cost is definitely a consideration, but I'd still love to hear what's out there today that would work in this system. Thanks, Merry Christmas, and God Bless!

Every Good Wish,
Doc

P.S. Just before our most recent snow and ice storm, I brought up the recent 4645 enclosure (thanks, Grumpy!), and SB gave a bit of a gasp when she saw it, and the 4645 I already have!! Though she is all for me playing around with these goodies, and loves our current system, she was a bit unprepared to see TWO 4645's together, AND the L300's, all in the same room!! :eek::bouncy:

[grumpy]

I was recently contemplating this:

http://www.diyaudio.com/store/amplifier-kits/amp-camp-kit-23/aca-bundle.html

for 2405 application. (can't specifically recommend it, esp. re noise, as I've not
tried it yet... just looked like fun) :)

[Tim Rinkerman]

For high-fi sound reinforcement we used to use BGW 750's powering 4 slots per channel. Amplifiers have to work really hard to reproduce high frequency information accurately. The ultimate choice is the one that sounds the best to you..

[JuniorJBL]

I have some Niles Audio High current 2 channel 50 w per and they sound really nice. They have pretty nice power supplies as well. YMMV;)

[Rapidan]

I've had good luck and good sound from those little T-amps, if 10-15 watts is really all you need a Topping TA20 or similar might fill the bill. I use one in my office and it sounds pretty good, very smooth high end.

Doc Mark, I believe I have met you over at Spiritburner.com? If so, hello and small world!

[robertbartsch]

i cannot hear much from a 2405 slot.... too old now... this was confirmed by a hearing test.....

[Doc Mark]

Good Evening, All,

Thank you, very much, for your suggestions, Gentlemen. Much appreciated! I must, however, plead confusion on one point, however. I have always thought that the higher frequency components did not need super large, high power amps. And, I've always used the big amps for bass reproduction, and amps with less power for the mids, and less, still, for the HF stuff. Have I been doing this wrong all these years??!! When we used BGW amps, the big boys went on the bottom; same with Crown, et.al., and much smaller amps drove the HF stuff. WOW!! A BGW 750 for tweeters!!! : )

Grumpy, I'll check out the diy amp project, but in truth, think I'd rather have something that I don't have to build. Time is always in short supply with me, it seems, as our little business demands much of it. (That's one of the main reasons why this project has taken SOOOO long to even get started!!)

JuniorJBL, good to hear from you. Your Niles amp sounds like it might work out well. I'll check into it, and see what it offers, pricing, and other such info.

Rapidan, yes, I've been at CCS for more years than I can remember! What name do you go by over there? As with the other suggestions, I'll most certainly check out the TA20 amp, as it sounds promising. Are you new to JBL, or have you been at it a long time? I was into JBL much earlier than stoves, though once I quit playing music professionally, I haven't used my stuff too much, other than home stereo, and that's how things still stand.

Thanks, again, to one and all, and I'll see which of your suggestions might work out for me in this project. It's funny how things snowball, though, when you begin actually digging into a long awaited project. Now, I've been thinking about sending my Crown VFX2A in for a rebuild, as it's a tad noisy these days. More stuff to consider, but I'm glad the Ashley is here, which, if all this comes to fruition, will more than likely be the one that is used full time. The Crown will just be an easy way to bi-amp the 2245's and the rest of the system, to get started. Thanks, again, and God Bless!

Every Good Wish,
Doc

[Rapidan]

Good Evening, All,


Rapidan, yes, I've been at CCS for more years than I can remember! What name do you go by over there? As with the other suggestions, I'll most certainly check out the TA20 amp, as it sounds promising. Are you new to JBL, or have you been at it a long time? I was into JBL much earlier than stoves, though once I quit playing music professionally, I haven't used my stuff too much, other than home stereo, and that's how things still stand.



Every Good Wish,
Doc

Thanks Doc, I haven't been over there for a while, my handle was either this or Short Tip, I'll have to go over and check. I've got an assortment of white gas backpacking stoves and parts I have been amassing since the 60's, in my Boy Scout days. I got interested in fixing them up after trying a Jetboil and a Pocket Rocket for hot lunches and coffee for my guide clients - neither one satisfied, but my Svea 123 and Optimus Hunter still do. You guys gave me a lot of help over there.

I've been a JBL fan since I splurged for my first pair of 4311's in my backroom 4-track studio in the 70's. I've used JBL ever since for business and pleasure, mostly pleasure now.

Great to talk with you again!

[stephane RAME]

2245 - BGW 750
2123 - Crown DC300
2445 - Crown D150
2405 - Crown D45

Stéphane

[robertbartsch]

Altec Lansing used bi-amplification in theaters early on - before solid state amps were popular, and that is when I became interested in the concept. I played with bi-amp and tri-amp applications a fair amount over the years....

Frankly, building these systems is VERY hard to pull off well. In the early days, I suppose they did this because there were no really potent commercial amps. Obviously, powerful reliable solid state amps changed all this.

My thought now is keep it simple...

What ever you decide, realize that if you are not 20 years old anymore, hearing the slot tweeter at those high freq. may be a challenge, so spend your dollars wisely...

[hjames]

Altec Lansing used bi-amplification in theaters early on - before solid state amps were popular, and that is when I became interested in the concept. I played with bi-amp and tri-amp applications a fair amount over the years....

Frankly, building these systems is VERY hard to pull off well. In the early days, I suppose they did this because there were no really potent commercial amps. Obviously, powerful reliable solid state amps changed all this.

My thought now is keep it simple...

What ever you decide, realize that if you are not 20 years old anymore,
hearing the slot tweeter at those high freq. may be a challenge, so spend your dollars wisely...

Doing Bi amp well is not so hard these days - I ran my 4341s in biamp mode first with JBL/UREI M522 and JBL/UREI amps,
then later with an Ashly active crossover and a pair of Adcom GFA555 amps ...
Phil does it as well with the Ashly and a pair of Crown amps on his 4345s.

I added 2405 slots to my L200 cabinets and built a 4333 crossover to run as passive 3 ways ...
but the slots have a great rep and a great resale if my ears fade from grace ...

I think Doc has it covered well!

[Doc Mark]

Good Morning, All,

Looking at Stephane's suggested amp list gives me the "warm and fuzzy feeling"!! :bouncy: I guess that, since we used Crown and some BGW, "back in the day" of playing music professionally, they still attract me, probably do to my trust and familiarity with those brands and amps! More food for thought, in any case. If I score a few more Crown amps, hopefully, the Series II stuff, than I could have an all-Crown system, which sounds good to me!

Heather, your thoughts about bi-amping the bottom end, and running the rest of the transducers via a regular crossover, are more certainly in the forefront of my thoughts on all this, as another option to an all active system. Though it's been years since a built a crossover, I actually used to wind my own air coils, and always had good luck with them. In fact, I still have two huge coils downstairs that I wound for subwoofer use, simple 12db/octave stuff.

Thanks, again, to one and all, for your suggestions. One strong consideration for me is the sound of the high end. I have grown to love the sweet open sound that H/K amps offer, and don't want to change that with whatever amp powers the 2405. I guess the proof is in the listening, when all is said and done. Talk to you all soon. Merry Christmas to one and all, and God Bless!

Every Good Wish,
Doc

[BMWCCA]

As Heather says, I use the Crown PS400 on the bottom of my 4345s and the PS200 for the upper-end through the charge-coupled networks built from the schematic in the DIY 4345 thread, and the Ashly. Works great for me. I did purchase a D75A to use in a bi-amp version of my childhood 030 system but haven't tried it yet. I also have a couple VFX2-A Crowns I thought I'd try in that application.

The results in bi-amping my 4345s are so stunning that I really have no pressing need to alter or go beyond what I have. I now have a Crown Studio Reference-II I thought I'd try on the bottom-end but just for curiosity. I find no limit to, nor do I have any dissatisfaction with, the current bass performance from the system. I just always wanted a Studio Reference, so I might as well give it a try. And, yes, I do recall Greg's comments about the ring-radiator's performance through a network and his suggestion for a separate small amp. I just have absolutely no disappointment in the system's current performance.

I will say I liked the results of switching from DC300A-II and D150A-II to the PS-series amps. So much so that I've laid in multiple spares of each, and the D-series workhorses are retired and dormant except in my old Mac C-20 system from high-school where the basic D150, my first Crown, the one without the faceplate, still works fine. I keep that system "all original" since I purchased the Crown and the L112s new while the C-20 was purchased used before either the amp or the speakers and I've owned them all ever since. I consider it my nostalgia system to use a a base-line while the 030 is in storage!

Back on topic, I'd think you might like to try a used D75A (or older D60) or new D45 (http://www.daleproaudio.com/p-18846-crown-d45-1ru-stereo-power-amplifier-25-watts-per-ch-at-8-ohms-used.aspx?gclid=COztkJ-KxLsCFS4aOgodVFsATw) for your application. They're available new for not much more than that project amp and used (http://www.guitarcenter.com/In-Store-Used-USED-CROWN-D-45-STEREO-POWER-AMPLIFIER-109670859-i3521633.gc?source=4WWRWXGP&gclid=COuWloiLxLsCFSUOOgodVBEAOw&kwid=productads-plaid^18283950120-sku^109670859@ADL1U@ADL4GC-adType^PLA-device^c-adid^27490280802) for so little that you might as well add one to your collection.

[Doc Mark]

Hi, BMWCCA,

I remember reading about your experiences with your various systems through-out your life. Fun stuff, and always enjoyable!

Thanks for your thoughts on bi-amping, and the Crown amps you suggested. I've already got my eye on a pair of them: D150A Series II, and a D60. Looking at a D75, too, just in case the D60 doesn't come to hand. We'll see where it all goes from here. Buying an amp, unseen, and unheard, is rather like buying a pig in a poke. But, I've never had any problems with used Crown gear in the past, and with the prices being far more able to fit into our budget, it would probably be best to go that route right now. Thanks for your thoughts and suggestions, as always, and God Bless!

Every Good Wish,
Doc

[JuniorJBL]

Doc

If you want to stay all Crown there are some Macro Reference on CL here in Denver I could help you aquire!!

http://denver.craigslist.org/ele/4201705263.html

[Doc Mark]

Hi, JuniorJBL,

WOW!! Huge brutes of amps, they are! My mouth is watering, just looking at them. However, I'm afraid price and logistics won't work out for me, right now. But, I very much appreciate your kind and generous offer to help. If I had a few more coins of "play" money in my jeans right now, I'd certainly give this Gent a call. Thanks, again, and God Bless!

Every Good Wish,
Doc

[more10]

Nelson Pass DIY class-A amps (https://www.passdiy.com/project/amplifiers). Maybe a cheap Tripath kit (http://shop.41hz.com/shop/) or readymade Chinese Tripath (http://www.ebay.com/sch/i.html?_trksid=p2047675.m570.l1313.TR10.TRC1.A0.Xt opping+tp&_nkw=topping+tp&_sacat=0&_from=R40). Or cheap Chinese tube amp (http://forums.audioreview.com/amps-preamps/$189-appj-miniwatt-n3-single-ended-triode-37765.html).

[1audiohack]

If you use a Crown D75 you will have to use a protection cap for your 2405. They have a DC bump several seconds after power down. The D45's do not do that. I have directly driven my 2404's and 2405's with D45's for years with no issues ever. If I remember right the D45's are about 13V max out so they will clip at about 14 Watts into a 12 Ohm load like the 2405. At home everything else is usually plenty loud. I have never lit the IOC lights at home.

Oh yeah, I think they sound fine on top.

All the best,
Barry.

[robertbartsch]

I bought my first pair of slots (077) in 1975. Since then, I have accumulated three other pairs (2405s) and also a pair of 075s (bullets).

I remember seeing them for the first time in sound reinforcement applications - like sets of 15 per side in rock concerts.... I'm not sure how they were driven..... ...probably Crown solid state.... This was the era when JBL blew past Altec in sound reinforcement ....

I'm not sure when they went out of production but the run was very long because nothing else can touch them... I assume this had something to do with the advent of titanium frams...

[Dan]

For my 3 way active I'm using

2245 - Crown K1
2118 - Hifimediy T1 (tripath 2050 chip) 50 watts
Tad 2002 - 41hz Amp 6 (tripath 2020 chip) 12 watts, output in parallel, battery powered, 1 amplifier per driver.

The Tripath amps are very smooth. The 2020 chip is a lot smoother than the 2050 chip.

I also have 2 of each, Crown D-300II and D-150II that I don't use.

Dan

[BeDome]

I own a number of vintage amplifiers and if I was going to classify one amp as incredible on HF or almost anything it would be my ancient Yamaha P2050 (P-series in general - I own several). The entire series, actually. If I can find it I will post the amp attempting a five Hz square wave. The factory tested them this way before they shipped them. I kept the test papers for some of the early ones I have.

The test graph looks really close to a square wave ... at 5Hz, 100Hz, 1KHz, 10KHz. But, I know, we would all like to see how they perform at 20KHz or maybe 100KHz.

What else I can tell you is that they are quiet. So little hiss that you will never notice it sitting a couple of feet away.

[BMWCCA]

Hmm … I hear no hiss when I put my ear right up against my 2405s driven by a Crown PS-200.

[Doc Mark]

Evening, All,

Ok, so if the hunt for a small amp is narrowed down to older, more affordable, Crown amps, which is the "Best of Breed", D45, D60, D75, or D75A? I had decided that, just to cover the base, a protection cap would be used for both the 2445, and the 2405, no matter which amp I choose. So what are the pluses and minuses of this stable of older Crown amps? Which would you choose, and why? Thank, and God Bless!
Every Good Wish,
Doc

[Doc Mark]

Greetings, All,

Forgot to tell you: I pulled the trigger on a very nice Crown D150A SeriesII a few days ago! Today, visiting a friend in San Diego, a huge and heavy Peavey CS1200X Professional amp came home with me, as a gift. Don't know, for sure, what this big amp will do, if anything, in my project system, but it was a fun gift, anyway! So all that's left, for the most part, is a small amp for the 2405's. Seeing all this finally coming together is really enjoyable and fun! Take care, and God Bless!

Every Good Wish,
Doc

P.S. The D150 II is for the 2445 drivers.

[Doc Mark]

Evening, All,

Ok, so if the hunt for a small amp is narrowed down to older, more affordable, Crown amps, which is the "Best of Breed", D45, D60, D75, or D75A? I had decided that, just to cover the base, a protection cap would be used for both the 2445, and the 2405, no matter which amp I choose. So what are the pluses and minuses of this stable of older Crown amps? Which would you choose, and why? Thank, and God Bless!
Every Good Wish,
Doc

Evening, All,

So, any help on which of the smaller Crown amps might. Be "Best of Breed"? Thanks, and Merry Christmas!

Doc

[Mannermusic]

Evening, All,

So, any help on which of the smaller Crown amps might. Be "Best of Breed"? Thanks, and Merry Christmas!

Doc

Hi Doc - I ran D60s on a tri-amp (077 UHF) for a couple decades with good results. Recommend getting any old stuff "refreshed," as you know. I've used Crown amps (new) since the seventies and they all finally degrade in one way or another. Noise, stability. Sneaks up on you! But, you know the drill! With the drivers you are using, the 3155 network (bi-amp) would make the whole exercise simpler. Similar to Giskard's 4345 project (thread). Mike

[martin2395]

Hiss/noise is often a problem with vintage gear but after recap and re-adjustment they will be good to go for the next decade. :)
I wouldn't run my supertweeters with a vintage amp that has no output relay and DC protection.

[Doc Mark]

Good Morning, All,

After spending some time checking out the different small Crown amps, I've narrowed my choices to either the D45 or the D75. I think the D45 will work perfectly with 2405's, but also see the D75 as being a little more versatile, if I ever wanted to use it for something else. A third option is to get the D45 now, and add a D75 fairly soon, just for fun! Any thoughts about the D45 compared to the D75? Thanks, friends, and I hope you all had a lovely Christmas!! Take care, and God Bless!

every Good Wish,
Doc

[Doc Mark]

Howdy, All,

Decided to go with the D45, to start, and bought what appears to be, and what I HOPE will be, a nice one! After it arrives, I'll post a report. Thanks for all the great comments and suggestions! Take care, and God Bless!

Every Good Wish,
Doc

[BMWCCA]

Howdy, All,

Decided to go with the D45, to start, and bought what appears to be, and what I HOPE will be, a nice one! After it arrives, I'll post a report. Thanks for all the great comments and suggestions! Take care, and God Bless!

Every Good Wish,
Doc

Hey Doc,

I pulled the trigger on a D45 recently and it arrived today. Looks like new. Playing it with some small sacrificial JBLs right now to "burn" it in. Sounds very nice! It's hooked up to a Soundcraftsmen PRO PT-TWO sitting atop a spare PS400 and PS200 in the same room for testing and evaluation. This brings the Crown collection to (at least one of each) D45, D75A, D150, D150A-II, DC300A-II, PS200, PS400, PL3, Studio Reference-II, plus SL2, FM2, FM3, VFX2-A.

How's your project coming? I'm all set now to resurrect the 030 system in bi-amp form. All I need is space and time!

[Lee in Montreal]

In regard of a power amp for that 2405, am I the only one having problems when using amps with output relays? After a while, the relay o one side stops kicking in. And will work only at higher volume. I had two amps do that one me... I tend to believe that the 2405 needs so litte power that it affects the relays.

[Doc Mark]

Hey Doc,

I pulled the trigger on a D45 recently and it arrived today. Looks like new. Playing it with some small sacrificial JBLs right now to "burn" it in. Sounds very nice! It's hooked up to a Soundcraftsmen PRO PT-TWO sitting atop a spare PS400 and PS200 in the same room for testing and evaluation. This brings the Crown collection to (at least one of each) D45, D75A, D150, D150A-II, DC300A-II, PS200, PS400, PL3, Studio Reference-II, plus SL2, FM2, FM3, VFX2-A.

How's your project coming? I'm all set now to resurrect the 030 system in bi-amp form. All I need is space and time!

Evening, BMWCCA,

Phil, I'm still waiting for Ken (Edgewound) to finish refoaming the 2245's. The surrounds he had did not fit as well as he had hoped, so he had to order new ones. His work is so fine, it's worth the wait, so I'm ready when he's ready! I was very happy with the sound of both the D45, and the D150AII I recently received, and interestingly enough, even that Peavey CS1200X sounded pretty good, with no extra hiss or noise, other than the fan, which is a bit too much of a good thing, at least to me. I have given thought to checking into a quieter fan, and will contact Peavey to see what they might recommend. In the old days, we used "Whisper fans", and they seemed to work well. But, that's been many years ago, and I need to see what's out there today.

Thanks for letting me know about your own D45, and congrats on getting a nice one, as did I!! Well done!! Your Crown collection is outstanding, and something to be admired. I'm looking forward to moving forward with my project, whenever the 2245's are ready to go. Take care, and God Bless!

Every Good Wish,
Doc

[hjames]

In regard of a power amp for that 2405, am I the only one having problems when using amps with output relays? After a while, the relay o one side stops kicking in. And will work only at higher volume. I had two amps do that one me... I tend to believe that the 2405 needs so litte power that it affects the relays.
... the 2405s really don't need much power at all!
How about using one of those T-amps -
they are mighty cheap and pretty clean.

I'm not triamping my L200 3ways, but its certainly worth a try ...
Seems like $25 is a worthwhile price to try one, doncha think?
http://www.amazon.com/Upgraded-LP-2020A-Lepai-Amplifier-Shipping/dp/B00C2P61FO/ (http://www.amazon.com/Upgraded-LP-2020A-Lepai-Amplifier-Shipping/dp/B00C2P61FO/)

I got one of these around Christmas and have been playing with it -
my original plan was to amp an iPod with a pair of walnut Minimus 7 speakers,
but I tried and was amazed what I did with a pair of Ruark Talisman II speakers.
It WILL get noisy if you push too far, but below that point its very impressive!

61375

61376

[1audiohack]

In regard of a power amp for that 2405, am I the only one having problems when using amps with output relays? After a while, the relay o one side stops kicking in. And will work only at higher volume. I had two amps do that one me... I tend to believe that the 2405 needs so litte power that it affects the relays.


I have experienced this also with amps driving HF horns.

Barry.

[BMWCCA]

... the 2405s really don't need much power at all!
How about using one of those T-amps -
they are mighty cheap and pretty clean.

I'm not triamping my L200 3ways, but its certainly worth a try ...
Seems like $25 is a worthwhile price to try one, doncha think?
http://www.amazon.com/Upgraded-LP-2020A-Lepai-Amplifier-Shipping/dp/B00C2P61FO/ (http://www.amazon.com/Upgraded-LP-2020A-Lepai-Amplifier-Shipping/dp/B00C2P61FO/)

I got one of these around Christmas and have been playing with it -
my original plan was to amp an iPod with a pair of walnut Minimus 7 speakers,
but I tried and was amazed what I did with a pair of Ruark Talisman II speakers.
It WILL get noisy if you push too far, but below that point its very impressive!
Lots of attractive little amps out there these days. Just like there are many Chinese DACs available for pocket change. I'm amazed at what these small SS Crowns will do with even the lowest-level small speakers. And they don't need wall-warts for power, I feel good having something else actually Made in USA, and they seem to work forever. If I lined up all my Crown amps for which I'd paid within ten-bucks of a hundred-dollars for they would include a D45, D75A, DC300A-II, PS400, and more. Not knocking the the T-amps. I find the technology rather astounding and the bang-for-the-buck hard to overestimate.

I went to the normal Crown support site for "discontinued" amps and couldn't find a tech sheet on the D45. Then I remembered it was still in production, at least until recently, so it was still supported in the current-products section. A quick Google search showed new prices as high as over $700. I patted myself on the back once more.

Maybe I spent four-times as much for an honest 25wpc at 8-ohms but I can tell you this D45 also makes an absolutely incredible headphone amp! Maybe one day I'll splurge for a Lepai and do some A-B comparisons. I did notice that one Amazon review noted that those more satisfied with the Lepai are using better speakers than those who are less happy with their purchase.

Off to work I go. Enjoy your Sunday. :banghead:

[Lee in Montreal]

I have experienced this also with amps driving HF horns.

Barry.

Next amp I use to power some 2405 wil have no output relay. And they'll have to have no popping on actuation/deactuation. :eek:

[subwoof]

Many of the older "D" series amplifiers have that turn-off "thump" when the amp is turned off.

Most of the time it can be traced to the change in value of the small electrolytic caps used on the +/- 10V supply. The zener diodes were mounted too close to the dropping resistors and too close to the caps so all would heat up and the caps would dry out...amongst other issues.

When I repair / restore these I replace the dropping resistors and the caps with higher wattage and higher temp ( 105C vs 85C ) to ensure long (new) life. Still it is found sometimes that different loads will cause the supplies to drop differently and the thump is still there so changing the cap size usually fixes this.

The PS amplifiers have an additional Cmos audio switch ( chip ) that breaks the connection from the input opamp chip to the power stages which eliminates this problem.

I have a stack of D60/D75 amps here in the house I am restoring and when done I will get to the D150's and 300's.. probably 60 amps in total of this series. anybody need power?? too cold to do anything except solder........

:)

[1audiohack]

anybody need power?? too cold to do anything except solder........
:)


I do. VZ power. :^)

Also, all my D75's pop when powered down and none of my D45's do. I thought it was just the way they were. If that's not the case I need to look and see if I can fix them.

Barry.

[robertg]

Many of the older "D" series amplifiers have that turn-off "thump" when the amp is turned off.

Most of the time it can be traced to the change in value of the small electrolytic caps used on the +/- 10V supply. The zener diodes were mounted too close to the dropping resistors and too close to the caps so all would heat up and the caps would dry out...amongst other issues.

When I repair / restore these I replace the dropping resistors and the caps with higher wattage and higher temp ( 105C vs 85C ) to ensure long (new) life. Still it is found sometimes that different loads will cause the supplies to drop differently and the thump is still there so changing the cap size usually fixes this.

:)
Does anyone know what capacitors he was talking about here? My D45A amps all make a thump or a pop when turned off, and this one was really bad. R1 and R2 were very hot at one time, so I'm thinking D1, C11, and C2 should be replaced with the corresponding components around R2.

I should be able to solder in new components myself.

[Mike Caldwell]

Regardless of the amp choice you may want to consider a DC blocking cap in series with the 2405. Something like a 6uf would put the cap cutoff well below the where your most likely crossing into the 2405.

[grey]

I'm going through the same issues right along with you, Robert.

So far I've tried the D45(pristine and newer model), a 1U QSC unit, and two UREI 6215. I've managed to get one UREI 6215 working out of two. Both the Crown and the QSC exhibit DC on shutdown. The working UREI has a 60Hz hum that I'm still troubleshooting. I put a Solen 5.6uf (protection on HP@7KHz)on the outputs and measured both shutdown DC and hum through this capacitor.

Took a chance on another 6215 that had severe chassis damage. The board showed up super clean. It has 2mv constant on one channel that I'm not able to adjust out and that's it. No other DC voltage detected anywhere on power up or down. One of the few 1U amplifiers with a relay on the outputs is what I'm finding. I will be doing the maintenance, swapping it into the clean chassis, and adding a perforated hood so it can breath.

I've looked into the class D stuff, but I don't understand the output protection on them if there is any at all. I've also looked into what Greg Timbers is using on his Everest tweeters. It is a Pioneer Elite integrated with a "bypass" or "direct" button.

[robertg]

Regardless of the amp choice you may want to consider a DC blocking cap in series with the 2405. Something like a 6uf would put the cap cutoff well below the where your most likely crossing into the 2405.
I have a couple of these that I am going to use for protection, 5.6uf.

[robertg]

I'm going through the same issues right along with you, Robert.

So far I've tried the D45(pristine and newer model), a 1U QSC unit, and two UREI 6215. I've managed to get one UREI 6215 working out of two. Both the Crown and the QSC exhibit DC on shutdown. The working UREI has a 60Hz hum that I'm still troubleshooting. I put a Solen 5.6uf (protection on HP@7KHz)on the outputs and measured both shutdown DC and hum through this capacitor.

Took a chance on another 6215 that had severe chassis damage. The board showed up super clean. It has 2mv constant on one channel that I'm not able to adjust out and that's it. No other DC voltage detected anywhere on power up or down. One of the few 1U amplifiers with a relay on the outputs is what I'm finding. I will be doing the maintenance, swapping it into the clean chassis, and adding a perforated hood so it can breath.

I've looked into the class D stuff, but I don't understand the output protection on them if there is any at all. I've also looked into what Greg Timbers is using on his Everest tweeters. It is a Pioneer Elite integrated with a "bypass" or "direct" button.
I bet you bought that UREI 6215 that has been on eBay for a while? I have one that works perfect, and two with problems. They both have a tittle distortion at really low volumes. I bought them not working and my tech went through them. The STK chip was replaced and my tech thinks they are counterfeit. I gave up throwing money at them.

I'm almost of thinking of getting a six channel amplifier for the top three of my four-way. I've been looking at a Crown CP660 and an Elan A6 on eBay. Both are really cheap, but I can't find much information on them. Hopefully I can get these old D series Crown going with a few dollars in parts instead of buying something else.

[grey]

I bet you bought that UREI 6215 that has been on eBay for a while? I have one that works perfect, and two with problems. They both have a tittle distortion at really low volumes. I bought them not working and my tech went through them. The STK chip was replaced and my tech thinks they are counterfeit. I gave up throwing money at them.

I'm almost of thinking of getting a six channel amplifier for the top three of my four-way. I've been looking at a Crown CP660 and an Elan A6 on eBay. Both are really cheap, but I can't find much information on them. Hopefully I can get these old D series Crown going with a few dollars in parts instead of buying something else.

Yeah, the ebay beater:o:. Made an offer on it and it is way cleaner on the inside compared to the other two. Measured it and tested on a cheap speaker. The first one that i purchased had enough heat buildup to lift the pcb traces. A 6215 the hard way:banghead:.

Another option for multi-channel are the BGW units. They likely need a maintenance update as well unless they have a modern version.

[robertg]

I bought a couple of Ramsa WP-9055 amps off eBay. They were $100.00 each, new in the box, and they have a muting circuit on start up so no pop.