SDA 2A ohm reading help needed

astar13656

I bought a set of 2a's a few weeks ago, and the just don't sound nearly as good as my monitor 10's.

After searching this forum I found the SDA troubleshooting guide and downloaded it. After checking the values from the interconnect cable and the red and black hook up posts with a digital ohm meter, I see there is a problem. However, I don't know what the values tell me. Anybody want to help?
right/left
referance-meas./reference-mea

ic pin 2 to black terminal - 15.3 - none / 4.8- 4.7
ic pin 1 to black terminal- 4.8-4.8/15.3- none
ic pin 1 ti ic pin 2 - 10.5-none/10.5-none
ic pin 2 to red terminal - 10.5-none/0.0- 0.3
red terminal to black terminal-4.8-4.7/4.8-4.6
ic pin 1 to red terminal -0.0-0.3/10.5-none
none as in no reading, not 0.0

Schurkey

Might want to reformat the table. I can't make any sense out of it.

astar13656

ic pin 2 to black terminal right- reference value 15.3ohm actual-none. left,reference 4.8ohm- act 4.7ohm

ic pin 1 to black terminal right- ref 4.8 act 4.8 left ref15.3 act none

ic pin1 to pin 2- right ref 10.5- act none. left ref10.5 act none

ic pin 2 to red terminal. right- ref 10.5- act none. left ref 0.0- act 0.3

red terminal to black terminal right- ref 4.8 act 4.7. left 4.8 act 4.6
i

c pin 1 to red terminal right ref-0.0 act 0.3. left ref 10,5 act none
I'm not having much luck posting as a table. Does this make any sense?

gimpod

To begin with if you have SDA 2A's (1 tweeter, 2 6.5" drivers) your looking at the wrong chart (page 3 is for the original SDA 2's 2 tweeters & 3 6.5" drivers) you should be looking on page 5.

SDA 2A, Note: IC PIN #1 is the Large Blade and IC PIN #2 is the Small Blade, Also values are +/- 20%

DCR Check PointRight ChannelLeft Channel
IC PIN #2 TO BLACK TERMINALINF4.0
IC PIN #1 TO BLACK TERMINAL4.0INF
IC PIN #1 TO IC PIN #2INFINF
IC PIN #2 TO RED TERMINALINF0.0
RED TERMINAL TO BLACK TERMINAL4.04.0
IC PIN #1 TO RED TERMINAL0.0INF


Now if I'm reading you measurement's right (Table below) your with in spec if there SDA 2A's. Now don't forget that most Ohm meters set on the lowest range can also be off by +/- 1 - 2%

DCR Check PointRight ChannelLeft Channel
IC PIN #2 TO BLACK TERMINALINF4.7
IC PIN #1 TO BLACK TERMINAL4.8INF
IC PIN #1 TO IC PIN #2INFINF
IC PIN #2 TO RED TERMINALINF0.3
RED TERMINAL TO BLACK TERMINAL4.74.7
IC PIN #1 TO RED TERMINAL0.3INF

astar13656 wrote: »

ic pin 2 to black terminal right- reference value 15.3ohm actual-none. left,reference 4.8ohm- act 4.7ohm

ic pin 1 to black terminal right- ref 4.8 act 4.8 left ref15.3 act none

ic pin1 to pin 2- right ref 10.5- act none. left ref10.5 act none

ic pin 2 to red terminal. right- ref 10.5- act none. left ref 0.0- act 0.3

red terminal to black terminal right- ref 4.8 act 4.7. left 4.8 act 4.6
i

c pin 1 to red terminal right ref-0.0 act 0.3. left ref 10,5 act none
I'm not having much luck posting as a table. Does this make any sense?

Schurkey

First Guess: Ohmmeter test leads contribute .3 ohms, based on the two "dead short" test points showing .3 ohms.

If that's correct, the various "4.0 ohm" test points therefore correct to 4.4--4.5 ohm actual. Easily within the 20% tolerance, closer to 10%.

inspiredsports

So the measurement values seem to indicate everything is OK.

Now we need to look at setup issues and amplification.

Have you made sure left cabinet is on the left and right cabinet is on the right as you face the speakers.

Interconnect connected.

Cabinets approximately 8" from and perfectly square to the back walls (not toed in even a fraction of a degree).

Front Plane of Cabinets 90 degrees to floor.

Cabinet outside edges at least 3 feet from side walls.

Cabinet inside edges at least 6 feet from one another.

Listening position centered and about 8-12 feet back from front plane of cabinets

Lots of clean, high current amplification.

astar13656

"To begin with if you have SDA 2A's (1 tweeter, 2 6.5" drivers) your looking at the wrong chart (page 3 is for the original SDA 2's 2 tweeters & 3 6.5" drivers) you should be looking on page 5. "

Thanks Gimpod. Boy, do I feel stupid!

Inspired, All are ok except 8-12 feet back, closer to 6' due to room size.

I'm running a denon avr 3300, I had concerns if it would power them, but I couldnt pass up the chance to try.

Thanks for the quick replies.
Albert

inspiredsports

The 6' listening distance is a little bit close but should still be OK.

I'm guessing the Denon might be a little bit underpowered for what the 2A's like, and I'm not sure it's comfortable driving into a 4-5ohm load, although I think the Monitor 10's are also rated at 4 ohm.

astar13656

Ok, thanks. I have a Yamaha rv1105 in the basement, I remember it is switchable for 4 ohms. Maybe I'll dig it out and give it a whirl.

astar13656

I hooked up the SDA's to my Yamaha,set for 4 ohm front speakers and they sound much better. If I give it much volume the display lights flicker and it shuts down, sounds like I need to go amp shopping.

Schurkey

So...I'm curious:

WHAT in the circuitry of a receiver such as the Yamaha listed above CHANGES when the thing is "set" to accommodate a 4-ohm load?

I get that some tube amps have a four-ohm tap on the output transformer. Simple voltage-to-current swapping. But it's be extremely unusual for there to be an output transformer on a transistor amp; and certainly not in a mass-market receiver.

I remember years ago Harman-Cardon had a Citation-series transistor power amp with an 8-ohm/4-ohm selector. Seems to me it was rated at 200 watts into either eight or four ohms. I figured it did have a transformer inside...but I never bothered to confirm that. This would have been early-'90s; maybe very late '80's.

First Guess: the "4-ohm setting" engages an evil current limiting circuit; doesn't do anything to make the receiver more "compatible" with a 4-ohm load, except for preventing the amp from blowing up. But what do I know?

JPSmario

I have a pair of 2A's and run a Rotel RB980BX for power. rated at 120/ch into 8 ohms, it's high current and provides more than I care to use. They're usually available on A-gon for $250-$275
Jim

pjsjr

Well, I'll tell my SDA 2A story...

I bought mine, modified and updated here, from Disc Jockey(thanks, again) a few years ago. When I got them home and hooked up to an HK 3490 AVR I cranked up DSOM and blew a tweeter. Replaced said tweet and listened for a few months at lower levels...but still remembered the wonderful, full sound and that SDA effect when I auditioned them and wasn't getting it.

I switched to my Pioneer SX 1500TD and thought that it sounded better but not as good...at least I wasn't blowing tweets. Since I listen to mostly LPs I thought that I would upgrade there and changed TTs, cartridges and was rewarded with better sounding playback. Still wanting though.

I met some audio guys at several get-to-gathers herre, local and listened to them talk about feeding their speakers lots of watts. One especially feed his JBLs hundreds of watts...so I decided that if it was good enough for JBLs then it had to be good for my SDAs.

I haven't been able to find the Yamaha amp that I want but did find an interm M 45 amp and hooked it up and was rewarded with the sound that I've been missing:cheesygrin:.

So to the OP I suggest that you heed what inspiredsports said, "Lots of clean, high current amplification." Buy all the watts you can and get those SDAs singing. You won't be sorry. HTH, Preston

astar13656

I picked up an Adcom 5400 off craigslist and the SDA's are doing wondeful! Thanks for all the advice, guys.

F1nut

Schurkey wrote: »

First Guess: the "4-ohm setting" engages an evil current limiting circuit; doesn't do anything to make the receiver more "compatible" with a 4-ohm load, except for preventing the amp from blowing up. But what do I know?

More than you give yourself credit for as you nailed it!