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Old 24th February 2019, 12:13 AM   #7151
tjw59 is offline tjw59  United States
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Default Rogers Speakers Question

Maybe the caps in your crossovers need to be changed?

Also, with what are you driving the ACA? Make sure your source audio is not being clipped.


Quote:
Originally Posted by maf_au View Post
Hi, my ACA 1.6 sounds great.

Unfortunately, with the volume on reasonable sound, (not loud), it is crackling the tweeters on our Rogers speakers.

If I add an extra Pass ACA, would it make enough power for a variety of speakers that would stop the crackling in the speakers or should I swap to something else with higher power to build? Would want something that sounds as good as the Pass ACA.

Last edited by tjw59; 24th February 2019 at 12:14 AM. Reason: typo
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Old 24th February 2019, 01:29 AM   #7152
maf_au is offline maf_au  Australia
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Quote:
Originally Posted by tjw59 View Post
Maybe the caps in your crossovers need to be changed?

Also, with what are you driving the ACA? Make sure your source audio is not being clipped.
Good idea about the caps on the Roger. It is the Roger LS7 and bought it in around 1994.

Will test the system with our old amp, it never had the crackles though.

Driving the ACA is the AKSA Lender, with the system sorted for the ACA #957:
AKSA's Lender Preamp with 40Vpp Output
Quote:
Hugh recently reminded me that ideally, the input impedance on left transistor and feedback impedance should be about the same. So should leave R10=33k and play with R11 to get desired gain. So assuming you want about 15dB to drive ACA or F5, then use R10=33k and R11=6k8 and gain will be 15.3dB.
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Old 24th February 2019, 01:55 AM   #7153
tjw59 is offline tjw59  United States
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[QUOTE=maf_au;5708534]Good idea about the caps on the Roger. It is the Roger LS7 and bought it in around 1994.

Will test the system with our old amp, it never had the crackles though.

We drive Heil Air Motion Transformers with our ACA's. And it points out lots of ugly stuff in today's recording compression schemes. (.mp3 in particular) that we can't hear when we drive the AMT's with the passive crossovers and an Emotiva XPA 200.

Using a CD or Vinyl, though. It is positively stunning.

Still replace those 25 year old caps. And fiddle with different source material with your tests.
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Old 24th February 2019, 05:41 AM   #7154
RCV is offline RCV
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Hi! I'm from the Philippines. I ordered two ACA kits. I just completed one, and it's working now and sounds great.
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Old 24th February 2019, 11:51 AM   #7155
astromo is offline astromo  Australia
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Quote:
Originally Posted by RCV View Post
Hi! I'm from the Philippines. I ordered two ACA kits. I just completed one, and it's working now and sounds great.

Cool. Wait 'til you get the 2nd one, quadruple the fun..
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Old 24th February 2019, 06:20 PM   #7156
Hificat101 is offline Hificat101  United States
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Question. I'm planning on building a set of CSS Criton 1TDs this year. My plan to drive them was to start with a Hypex or Ice Power class D amp, then at some point biamp them. I had hoped to build a pair of ACA's to drive the tweeters, but the tweeter in the Critons is 4 ohm, and doesnt come in an 8 ohm variant.

The question is, the ACA is not designed to drive a 4 ohm load in balanced monoblock form, but would it make a difference if it were only fed crossed over signal over 1.8Khz?
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Old 24th February 2019, 10:33 PM   #7157
tjw59 is offline tjw59  United States
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Default Your mileage may vary - however:

I drive a 4 ohm loads with my ACA.

If your drivers are reasonably efficient to outstandingly efficient you won't need but a half a watt or so. Having used both active and passive crossovers. Crossed around 800 hz - ACA does an outstanding job driving my Heil AMT's and in the room I listen it is plenty of sound. With the stock crossovers, driving the woofers and tweeters and the crossover point around 1 kHz. It sounded pretty good.

Current setup uses an active crossover. Driving the AMT drivers with two ACAs configured as monoblocks: and use an Emotiva XPA-200 to drive the way less efficient ESS woofers. It is class A/B. But is a better choice for the back emf of the woofer.

All rooms are not the same as this one so cant vouch for how your setup will work. But can say the ACAs have run non stop hours and hours for about 8 months now working into the AMTs which are more like a 4 to 5 ohm resistor electrically. And they keep on sounding incredible.





Quote:
Originally Posted by Hificat101 View Post
Question. I'm planning on building a set of CSS Criton 1TDs this year. My plan to drive them was to start with a Hypex or Ice Power class D amp, then at some point biamp them. I had hoped to build a pair of ACA's to drive the tweeters, but the tweeter in the Critons is 4 ohm, and doesnt come in an 8 ohm variant.

The question is, the ACA is not designed to drive a 4 ohm load in balanced monoblock form, but would it make a difference if it were only fed crossed over signal over 1.8Khz?

Last edited by tjw59; 24th February 2019 at 10:35 PM. Reason: correction
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Old 25th February 2019, 12:07 AM   #7158
Hificat101 is offline Hificat101  United States
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Quote:
Originally Posted by tjw59 View Post
I drive a 4 ohm loads with my ACA.

If your drivers are reasonably efficient to outstandingly efficient you won't need but a half a watt or so. Having used both active and passive crossovers. Crossed around 800 hz - ACA does an outstanding job driving my Heil AMT's and in the room I listen it is plenty of sound. With the stock crossovers, driving the woofers and tweeters and the crossover point around 1 kHz. It sounded pretty good.

Current setup uses an active crossover. Driving the AMT drivers with two ACAs configured as monoblocks: and use an Emotiva XPA-200 to drive the way less efficient ESS woofers. It is class A/B. But is a better choice for the back emf of the woofer.

All rooms are not the same as this one so cant vouch for how your setup will work. But can say the ACAs have run non stop hours and hours for about 8 months now working into the AMTs which are more like a 4 to 5 ohm resistor electrically. And they keep on sounding incredible.
Thanks so much for the reply. Looks like I'm back in business. It seemed to me that driving a tweeter at 4 ohms would be much less demanding than driving a full range, multi driver speaker or woofer. That helps me narrow my options for the class D amp. I'm thinking a Hypex amp that will do around 125W @ 8 ohms would be fine for both full range use, and be good to go with 18 or 20W from a pair of ACAs. I thought it was strange to think of using a class D amp, and a pure class A amp on the same speaker, but I think it may sound awesome.
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Old 25th February 2019, 02:47 AM   #7159
RCV is offline RCV
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Just want to share my ACA. The 2nd kit is still in the works
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Old 25th February 2019, 03:55 AM   #7160
6L6 is offline 6L6  United States
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Amp Camp Amp - ACA
4ohm with balanced ACA is absolutely no problem.
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