What Adcom amp for my SDA/SRS’s?
Answers
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Thanks for the recommendation, verb - will do. I have called Meridian US, and while they tried hard to get a concrete answer out of the UK, it was a little fuzzy for my $. Have a call out to their go-to repair shop in Atlanta, founded by a couple of guys with 40 years of Meridian experience between them, so hope to get it right from them.
a multi meter will tell you -
So simply confirming continuity b/t the L/R ground pins on the balanced outputs will do it?
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So simply confirming continuity b/t the L/R ground pins on the balanced outputs will do it?
no on the amp binding post where the speaker cable goes. Amp off cables off. get back with the results. Some not all can have the negetive binding posts strapped together. I believe this to be a no no on any that are a balanced design. -
Oh right - the speaker outs... Continuity (zero resistance) between any combination of negative posts (amp is bi-wire ready), so looks like I'm good to go. Thx pitdogg.
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Oh right - the speaker outs... Continuity (zero resistance) between any combination of negative posts .
No. Continuity between left and right negatives. Not sure your amp is common ground. Manual shows to bridge your amp you need to jumper the negatives together and use the left + as positive and right + as negative.Gustard X26 Pro DAC
Belles 21A Pre modded with Mundorf Supreme caps
B&K M200 Sonata monoblocks refreshed and upgraded
Polk SDA 1C's modded / 1000Va Dreadnaught
Wireworld Silver Eclipse IC's and speaker cables
Harman Kardon T65C w/Grado Gold. (Don't laugh. It sounds great!)
There is about a 5% genetic difference between apes and men …but that difference is the difference between throwing your own poo when you are annoyed …and Einstein, Shakespeare and Miss January. by Dr. Sardonicus -
Ok - to be clear, I did check continuity between the L negative posts, and the R negative posts. Because there are two negative and two positive posts per side, I checked for continuity between all four combinations of L/R negative posts. All showed continuity - zero ohms.
Thus I think I'm ok - yes? -
Should be! Have you picked up the speakers yet?Gustard X26 Pro DAC
Belles 21A Pre modded with Mundorf Supreme caps
B&K M200 Sonata monoblocks refreshed and upgraded
Polk SDA 1C's modded / 1000Va Dreadnaught
Wireworld Silver Eclipse IC's and speaker cables
Harman Kardon T65C w/Grado Gold. (Don't laugh. It sounds great!)
There is about a 5% genetic difference between apes and men …but that difference is the difference between throwing your own poo when you are annoyed …and Einstein, Shakespeare and Miss January. by Dr. Sardonicus -
Blade/blade SDA SRS cannot use the isolation transformer that the newer versions can use, they cannot be made compatible with a non-common-ground amplifier and retain the SDA interconnect.
Connect an ohmmeter between the negative terminals of the two channels at the amplifier.
If you have LESS THAN 1 ohm (not "Continuity") you're good-to-go. Less resistance is better.
If you have MORE THAN 1 ohm AND you're certain that the amp is NOT a bridged/balanced design, you can run a jumper wire between the two negative terminals to achieve common-ground. I do this with my amplifier-of-choice. Some amplifiers have minimal resistance between the negative terminals. Some have hundreds of ohms of resistance. Some have infinite resistance. My amp has only 20 ohms between the negative terminals, and it makes my 1Bs unlistenable if I pull the jumper wire out of position. With the jumper wire, everything's wonderful. Lots has been said of the jumper wire reducing sound quality, but it's the only option when the speakers are not compatible with the isolation transformer. I'm not convinced there's a degradation of sound quality, but others more experienced than me, are. Perhaps it's dependent on the amplifier.
If you have a bridged/balanced design, you can use the speakers WITHOUT the speaker-to-speaker "SDA Interconnect cable" in place. You'll not get the SDA effect, but the speakers will make music.
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Not yet - and I'm not hefty enough to pick them up alone! ;-)
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Well post pics when you do. Lots of great info and people on this forum! Welcome!Gustard X26 Pro DAC
Belles 21A Pre modded with Mundorf Supreme caps
B&K M200 Sonata monoblocks refreshed and upgraded
Polk SDA 1C's modded / 1000Va Dreadnaught
Wireworld Silver Eclipse IC's and speaker cables
Harman Kardon T65C w/Grado Gold. (Don't laugh. It sounds great!)
There is about a 5% genetic difference between apes and men …but that difference is the difference between throwing your own poo when you are annoyed …and Einstein, Shakespeare and Miss January. by Dr. Sardonicus -
Blade/blade SDA SRS cannot use the isolation transformer that the newer versions can use, they cannot be made compatible with a non-common-ground amplifier and retain the SDA interconnect.
Connect an ohmmeter between the negative terminals of the two channels at the amplifier.
If you have LESS THAN 1 ohm (not "Continuity") you're good-to-go. Less resistance is better.
If you have MORE THAN 1 ohm AND you're certain that the amp is NOT a bridged/balanced design, you can run a jumper wire between the two negative terminals to achieve common-ground. I do this with my amplifier-of-choice. Some amplifiers have minimal resistance between the negative terminals. Some have hundreds of ohms of resistance. Some have infinite resistance. My amp has only 20 ohms between the negative terminals, and it makes my 1Bs unlistenable if I pull the jumper wire out of position. With the jumper wire, everything's wonderful. Lots has been said of the jumper wire reducing sound quality, but it's the only option when the speakers are not compatible with the isolation transformer. I'm not convinced there's a degradation of sound quality, but others more experienced than me, are. Perhaps it's dependent on the amplifier.
If you have a bridged/balanced design, you can use the speakers WITHOUT the speaker-to-speaker "SDA Interconnect cable" in place. You'll not get the SDA effect, but the speakers will make music.
Thanks for the post, Schurkey.
I did get zero ohms between negatives... but this is as read on my old school analog multimeter, with a minimum range setting of K ohm. It certainly looks like zero, but the smallest gradation on the dial is 100 ohm. Guess I better find a multimeter with a lower range setting.
Your comment on running w/o the SDA cable in place brings forward another question I had after reading some listeners disliked the SDA sound with modern hip/hop (or something like that) tracks. Have you (or anyone) run w/o the cable? If so, how is the sound quality? Are all drivers driven in this mode? -
Yup, you need a meter with a more-sensitive range. One ohm or twenty will look pretty similar on that meter, but there's a huge functional difference.I did get zero ohms between negatives... but this is as read on my old school analog multimeter, with a minimum range setting of K ohm. It certainly looks like zero, but the smallest gradation on the dial is 100 ohm. Guess I better find a multimeter with a lower range setting.
Thus my notation previously that "continuity" may not be good enough.
Whether one likes or dislikes the SDA effect is in the ear of the beholder. Try it and discover for yourself. Running without the cable on newer generations of SDA speakers like yours results in a loss of the SDA signal at the outside drivers, but those drivers still produce bass.Your comment on running w/o the SDA cable in place brings forward another question I had after reading some listeners disliked the SDA sound with modern hip/hop (or something like that) tracks. Have you (or anyone) run w/o the cable? If so, how is the sound quality? Are all drivers driven in this mode?
Older generations had SDA-only drivers, disconnecting the SDA interconnect cut all signal to them, they were then useless except as additional passive-radiator surface area--and not that good at being a passive radiator.
My SDA 1Bs are similar to your SRSs, pull the cable, the soundstage collapses to "within the area between the speakers" instead of extending beyond the speakers, but there's little tonal change. Very satisfying sound...if you didn't know what you were missing from the SDA effect.
Oh, yeah. Don't ever use the phrase "SDA effect", some folks around here are severely allergic to it. -
Update on the Meridian 559 question. A call to Meridian's go-to repair shop in Atlanta, and a better DMM, confirmed this amp is common ground.
Thanks for all your support - I'm going shopping. -
Update on the Meridian 559 question. A call to Meridian's go-to repair shop in Atlanta, and a better DMM, confirmed this amp is common ground.
Thanks for all your support - I'm going shopping.
Well, yet another update. After tinkering with the DMM I was lent - using it to measure resistance across a few pairs of speakers I own, I realized I'd not set the meter to the lowest setting possible (200ohm range). When I did and remeasured my Meridian amp, I found I have just over 20 ohms resistance. So now in a quandary, as the shop who knows this amp well say's it's common ground, but the meter says 20.1 ohm between L/R negatives. -
My amp also has 20 ohms between the negative terminals. I've heard of other "common ground" amps having as much as 200 ohms between the negative terminals of the two channels.Update on the Meridian 559 question. A call to Meridian's go-to repair shop in Atlanta, and a better DMM, confirmed this amp is common ground.
Thanks for all your support - I'm going shopping.
Well, yet another update. After tinkering with the DMM I was lent - using it to measure resistance across a few pairs of speakers I own, I realized I'd not set the meter to the lowest setting possible (200ohm range). When I did and remeasured my Meridian amp, I found I have just over 20 ohms resistance. So now in a quandary, as the shop who knows this amp well say's it's common ground, but the meter says 20.1 ohm between L/R negatives.
In my case, this is the result of two, ten-ohm resistors between the negative terminals and chassis ground. This is done to "reduce noise" on the output of the amplifier, I guess. Other amps might use different values for these resistors.
Bypassing those resistors with a three-dollar jumper wire poked into a negative terminal on each channel instantly makes the amplifier completely common ground and suitable for SDA use.
So long as "your" 20 ohms are similarly the result of resistors used to partially-lift the negative terminals from chassis ground, a similar jumper wire is all you'd need to fix the incompatibility.
If "your" 20 ohms is from something else, you might be screwed. Find a schematic, look for two ten-ohm resistors connected to each of the channel's negative terminals--one resistor for each channel.
Again, "bridged" or "balanced" amps are NOT COMPATIBLE, and a jumper wire will let all the smoke out of them. (But if your Meridians were of that sort, they shouldn't tell you they're "common ground".) -
In my case, this is the result of two, ten-ohm resistors between the negative terminals and chassis ground. This is done to "reduce noise" on the output of the amplifier, I guess. Other amps might use different values for these resistors.
Bypassing those resistors with a three-dollar jumper wire poked into a negative terminal on each channel instantly makes the amplifier completely common ground and suitable for SDA use.
So long as "your" 20 ohms are similarly the result of resistors used to partially-lift the negative terminals from chassis ground, a similar jumper wire is all you'd need to fix the incompatibility.
If "your" 20 ohms is from something else, you might be screwed. Find a schematic, look for two ten-ohm resistors connected to each of the channel's negative terminals--one resistor for each channel.
Schurkey - I believe my 20ohms from L/R arises from a similar design source as your's; when I measured from either L or R negative posts to the ground prong on the power inlet, I get 10ohms.
Just so I've got this clear, if one has a "common ground" amp, as it appears I do, one can jumper the negative terminals from each channel, and you're in business for any model SDA SRS. If the amp is not common ground (e.g. "bridged" or "balanced"), one must not use a jumper, but may use the isolation transformer only with "newer" models of SDA SRS', i.e. those with pin/blade connections for the SDA interconnect, NOT with blade/blade interconnects).
This will probably warrant another call to the repair guys in Atlanta to get confidence I won't smoke the amp by jumping the negatives. -
I agree. "I" think you're set for a jumper wire. But then, I'm not paying for the repairs if I'm wrong.Schurkey - I believe my 20ohms from L/R arises from a similar design source as your's; when I measured from either L or R negative posts to the ground prong on the power inlet, I get 10ohms.
There are some exceptions on the blade/blade arrangement. Some SDA 1Cs and 2Bs may have come with blade/blade interconnects, but they are fully adaptable to an isolation transformer. However, in general you're correct.Just so I've got this clear, if one has a "common ground" amp, as it appears I do, one can jumper the negative terminals from each channel, and you're in business for any model SDA SRS. If the amp is not common ground (e.g. "bridged" or "balanced"), one must not use a jumper, but may use the isolation transformer only with "newer" models of SDA SRS', i.e. those with pin/blade connections for the SDA interconnect, NOT with blade/blade interconnects).
That, or find a schematic.This will probably warrant another call to the repair guys in Atlanta to get confidence I won't smoke the amp by jumping the negatives.
