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chops

Crown D-75A amplifier OWNERS, please reply...

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Just use a Solen Fastcap.

If this will be used in conjunction with an electronic crossover and your intended crossover point is 400Hz, you will need alarger cap. I read that you shousl try to be 2 octaves below the electronic crossover point to avoid interferance

Google 'Rod Elliott" (spelling?) and read his articles on bi-amping. I don't have time now, but I can check them later. If you really like your drivers you shoudl also put a fuse in. Everone here was debating it to death btu I'm glad I did, it saved my K77's.

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Just use a Solen Fastcap.

If this will be used in conjunction with an electronic crossover and your intended crossover point is 400Hz, you will need alarger cap. I read that you shousl try to be 2 octaves below the electronic crossover point to avoid interferance

Google 'Rod Elliott" (spelling?) and read his articles on bi-amping. I don't have time now, but I can check them later. If you really like your drivers you shoudl also put a fuse in. Everone here was debating it to death btu I'm glad I did, it saved my K77's.

Yes, I'll be crossing the 902s over at 700-800Hz via a new Rane AC 22B. This will be a 4th order Linkwitz filter. The 50uF cap is only being used for amp turn-on/off protection, not as a crossover point.

BTW, this is for Michael.... whip.gif

LOL

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Just use a Solen Fastcap.

If this will be used in conjunction with an electronic crossover and your intended crossover point is 400Hz, you will need alarger cap. I read that you shousl try to be 2 octaves below the electronic crossover point to avoid interferance

Google 'Rod Elliott" (spelling?) and read his articles on bi-amping. I don't have time now, but I can check them later. If you really like your drivers you shoudl also put a fuse in. Everone here was debating it to death btu I'm glad I did, it saved my K77's.

Yes, I'll be crossing the 902s over at 700-800Hz via a new Rane AC 22B. This will be a 4th order Linkwitz filter. The 50uF cap is only being used for amp turn-on/off protection, not as a crossover point.

BTW, this is for Michael.... whip.gif

LOL

I realize that you are not using the cap as a crossover. I have the same Crown Amp. Because you are not using it as a crossover you need to keep the caps's rolloff point two octaves below your 700 to 800 hz actual crossover point. Without looking at a chart, I am assuming that you are covered.

Check out the Rod Elliott article, its a must read for anyone using an active crossover.

Chris

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Just use a Solen Fastcap.

If this will be used in conjunction with an electronic crossover and your intended crossover point is 400Hz, you will need alarger cap. I read that you shousl try to be 2 octaves below the electronic crossover point to avoid interferance

Google 'Rod Elliott" (spelling?) and read his articles on bi-amping. I don't have time now, but I can check them later. If you really like your drivers you shoudl also put a fuse in. Everone here was debating it to death btu I'm glad I did, it saved my K77's.

Yes, I'll be crossing the 902s over at 700-800Hz via a new Rane AC 22B. This will be a 4th order Linkwitz filter. The 50uF cap is only being used for amp turn-on/off protection, not as a crossover point.

BTW, this is for Michael.... whip.gif

LOL

I realize that you are not using the cap as a crossover. I have the same Crown Amp. Because you are not using it as a crossover you need to keep the caps's rolloff point two octaves below your 700 to 800 hz actual crossover point. Without looking at a chart, I am assuming that you are covered.

Check out the Rod Elliott article, its a must read for anyone using an active crossover.

Chris

Well yeah, that's what "Tech Letter 205" from Altec says.

I'm quite familiar with active crossovers and how to set them up as I've used one in my home system before and have had several in my car audio systems. It's just a matter of getting this whole amp thump/driver protection thing right. I have NO questions about the active crossover at all. [:)]

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Just an update...

I now have 2 Solen 51uF caps on their way here from Parts Express so I can safely use the D-75A on my Altec drivers.

Also on its way here is a Rane BB 22 Balance Buddy so I can convert the unblanced -10dBV output of my receiver to balanced +4dBV before going into the Rane AC 22B crossover and Crown amp.

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Tiger,

You can buy relays with time delay built in. Just get one with a 120VAC "coil" and plug it into a switched outlet on your pre-amp. Wire the speaker lines throught the DPDT contacts and set the delay for whatever you want, like about 10 seconds.That way the speakers will stay un-connected until things settle down.

Longfellowe

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Another update...

I got the D-75A in today. It's in amazingly great, mint shape for a 12 year old amp! There are ZERO marks on it!

The only flaw was that the potentiometers somehow came loose and someone had spun the knobs so that the wires inside had become twisted and came in contact with eachother. So before doing anything else, I pulled the lid off, pulled the potentiometers out, untwisted them, seperated the wires, put them back in, snugged them down nice and tight and closed it back up.

Before I decided to hook it up to my system, I first connected a small pair of RatShack 2-way bookshelf speakers and my old Sony DVD player up to it. With the gains all the way down, I switched it on. No thumps, snaps, nothing. I hit play on the player and started turning up the gains. Everything worked and sounded fine! I let it sit there and play for about an hour or so while I did a few other things around the house including running a pair of interconnects up to the front of the room and running the speaker cables up to the front, as well as going and getting dinner cooking. Multi-tasking baby!! LOL

Anyway, I just want to say that this amp sounds great! Of course, once I get the proper XLR cables and a balanced signal going to it, I'm sure it will get even better. This amp even adds just a little more sparkle to the sound and has also opened up the soundstage a little more. Me likes!

And what would this post be without at least one good picture. Here it is with the Rane crossover sitting up top. The Rane isn't connected yet but will be soon.

DSCF3304.jpg

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ooooo, pretty lights. Nice shot Chops! And nice little biamp setup.

Appreciate your very careful 'new old amp setup' instructions. I just got done cleaning and testing all of my power amps using an old pair of speakers. If I blow up something, I want it to be something disposable!

Michael

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There is just enough room in a Crown D75a to add a 120VAC DPDT relay next to the power switch.  I desoldered the green and yellow wires from the output terminal board and ran them to the relay and back.  I picked up 120V from the terminal strip in front of the amp.  The relay drops out immediately on power down so you don't get the obnoxious noise or thump in the speakers.

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On 5/12/2019 at 12:43 PM, telewizard13 said:

There is just enough room in a Crown D75a to add a 120VAC DPDT relay next to the power switch.  I desoldered the green and yellow wires from the output terminal board and ran them to the relay and back.  I picked up 120V from the terminal strip in front of the amp.  The relay drops out immediately on power down so you don't get the obnoxious noise or thump in the speakers.

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Now you just need a time delay at power on and you'd be stylin'. Also I would suggest a small power resistor perhaps 10 ohm 5 watt across the NC contacts to speaker - (ground).

Man this is an OLDdddddddddddd thread

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On 7/6/2006 at 11:50 AM, colterphoto1 said:

very descriptive and quite correct from my experiences. I love that 'final fart' bit!

ROFTLMAO

Could be the name of a Cheep Effects song! The Final Fart!

John Kuthe...

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I have to say I really like the D-75, a little hot rodding like suggested would make a great little amp better.

 

Mine started making noise, in the amps, not the speakers so I switched to something else. But if I ever get a chance to go back I would, especially with no thump, I left them on to avoid it.

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