Amplifier for SDA 2B's

mirceasy

Hi guys,

I recently bought a pair of SDA 2B speakers with ther interconnect cable.
These were the first on the list, and the starting point of a future wanna be budget audiophile system.
After reading a lot of reviews and opinions about this speakers I came to realize that a complementary amplifier is required for driving them.
I have the possiblity of buyng one of the below mentioned amps. Can you please tell my, kindly sirs, which you believe that will be more appropiate for the SDAs, having in mind the common ground and current thirst requirements:

- Sony Scenario 7, TA-S7 amplifier (i can buy the whole shebang: amp, tuner, cd, etc.)
- Yamaha RX-770 stereo receiver
- Nakamichi SR-2E Stasis (I had a long time ago a SR-4E Stasis and i loved the sound made on Infinity Alpha 50 speakers) - It might be underpowered
- Luxman A-373
- Yamaha AX-700 (good power figures) or Yamaha AX-500
- Nad 306
- *Yamaha dsp A1000* - maybe the best option?

From your experience, have you ever paired any of those amps with SDA speakers?

Thanks for reading through.

Nightfall

You are looking at integrated amplifiers and receivers, not amps.

Nothing in that list gives me the warm fuzzies, personally. What city/state Craigslist are you looking on and what's your budget?

tonyb

Agreed ^^^

We have a few Parasound amps in the FM for sale which would match up well with SDA's.

mirceasy

Unfortunately, where I live (Europe - Ro) the amps market offer is pretty limited. I can find mostly german and japanese hardware. Also the available budget is around 100-150 bucks.
Given this speakers should I look more for vintage (20-25 years old) amps/int amps/receivers?

gmcman

Are there any military bases near you? Sometimes you can get some classified listings and I would imagine some electronics would come up...especially if people are relocating often.

That being said, I started with a Denon AVR3300, then a 5700, I also used a B&K ST202. The 5700 had a lot of grunt but when I switched to a B&K 200.2 the difference was quite noticeable. Not so much in the watts, but the available current in which the SDA's like.

The ST202 is a good amp, as well as the ST140 and you may be able to find one near your budget.

mirceasy

I searched the classifieds and i couldn't find any B&K amps for sale. American electronics are very rare in this part of Europe.
I did fund some Harman Kardon amps/receivers wich i know they are high current:
- Harman Kardon avr 3550
- Harman Kardon HK3370
- Harman Kardon DPR 1005
What do you tink about this HK's?

mirceasy

I searched the classifieds and i couldn't find any B&K amps for sale. American electronics are very rare in this part of Europe.
I did fund some Harman Kardon amps/receivers wich i know they are high current:
- Harman Kardon avr 3550
- Harman Kardon HK3370
- Harman Kardon DPR 1005
What do you tink about this HK's?

deronb1

Get the most powerful HK you can find. I run my 2Bs with a 130 wpc high current Onk. Works very well. So well actually, that i had no worries selling my Parasound HCA 1500a. The 2Bs are not hard to drive. You are correct in going the high current route.

mirceasy

I finally made up my mind for a Harman kardon HK980 amplifier but one of his specs troubles me. I'm refering to "Amplifier section dual mono construction".
Does this mean that it's not a common ground amplifier and i cannot use the SDAs interconnected through their specific cable?

deronb1

Yes, i believe that means it is NOT common ground. You would need a Drednought. Guys, please correct me if im mistaken.

mirceasy

http://www.manualslib.com/manual/65636/Harman-Kardon-Hk-980.html?page=4#manual

[Deleted User]

Hello,
That amplifier description doesn't necessarily mean it isn't a common ground design. In all likelihood there are two amplifiers sharing the same chassis, each with it's own power supply. That's usually what HK has built in the past. The common ground question is what happens at each of the negative speaker terminals and can they be connected together via the speakers.
However, since your particular speaker uses the pin/blade connecting cable there won't be any damage to the speakers or the amplifier if the amplifier isn't compatible.
Do you happen to have a volt/ohm meter (VOM) you can use?
Regards, Ken

mirceasy

Hello Ken,

Thank you for your reply, but are you sure if I use the speakers connected trough the IC cable and a non-common ground amplifier there wouldn't be any problems? I had the impression that because of the specified cable the speakers cannot be conneted to a non-common ground amp.
I will buy a VOM before reaching the amp seller. Between which amplifier's elements should i measure the impedance? Which value makes it a common ground amp?
I found the amp's service manual at: http://www.fichier-pdf.fr/2013/06/17/harmankardon-hk980-230-amp/preview/page/6/

Regards,
Mircea

[Deleted User]

Hello Mircea,
The SDA speakers that use the pin/blade cable prevent a non-common ground amplifier from being shorted out and damaged. Normally the amplifier provides the necessary ground connection for the SDA components of the speaker. If the amplifier isn't a common ground design then there won't be any audio from the SDA components.
In order to use that amplifier and produce the SDA effect it might be necessary to provide an external connection between the left and right negative terminals of the amplifier. But, you need to determine if that is not going to short out the amplifier. With most amplifiers this is not a problem, but some designs produce output voltages at both the positive and negative terminals. With the VOM set to read AC voltage and the amplifier connected to speakers and producing sound measure the AC voltage between the negative speaker terminal and any grounding point. For comparison measure between the positive speaker terminal and the same grounding point. You should see a constantly changing AC voltage at the positive terminal, but nothing at the negative.
Regards, Ken

[Deleted User]

Hello,
In reading the page you attached it refers to the amplifier as having a balanced output design and requiring a "floating" ground connection. This would mean it is not acceptable to use with the SDA speaker design. You would have to use either the Polk SDA non-common ground cable or one of the DIY "dreadnaught" cable system.

motorhead43026

That amp is not suitable power wise for SDA's anyway, keep looking.

deronb1

motorhead43026 wrote: »

That amp is not suitable power wise for SDA's anyway, keep looking.

Yeah, prob around 90 wpc into 6 ohms. Mo would be better.

mirceasy

Thanks guys for the heads up, I'll be searching for another suitable candidate, but the SDA 2B's are 4 ohms speakers, right, or 6 ohms?
If they are 6 ohms any powerfull 8ohms amplifier will do the job, no?

deronb1

6 ohm

deronb1

And around 90 to 91 sensitivity. You dont need a ton of power, but they are sealed. You'll need some decent juice to get the low end rounded out. Ive had luck with 125 wpc. Running 165 wpc into 6 ohms now and its great!

westmassguy

deronb1 wrote: »

And around 90 to 91 sensitivity. You dont need a ton of power, but they are sealed. You'll need some decent juice to get the low end rounded out. Ive had luck with 125 wpc. Running 165 wpc into 6 ohms now and its great!

They're not Sealed/Acoustic Suspension, rather Passive Radiator, which is akin to Ported/Bass Reflex. Passive Radiators are superior to ports in many ways, but are more difficult to design properly. Anyone with rudimentary skills, can design a ported system that will function properly. Passive Radiators, not so easy.

mirceasy

I finally bought a Denon DRA-825R and it seems that it's a good match for my speakers. However, sadly I discovered that my left speaker's tweeter appears to be dead.
The exact speakers model is SDA 2B 1989 (Real Wood) which I found out that uses the SL2000 tweeter.

Do you guys have any ideea if this one (or both) can be replaced with some other easy to find tweeter model, without having to modify the filters?
I live in Europe and i couldn't find this model on any european ebays or other electronic adds sites.
Also my impression was that with or without the Interconnect cable the speakers sounded the same - only one of the two mini speakers produced sound. This could be related to a crossover/filter problem?

boston1450

Will Polk ship to you ? You could change them out to RD0194's which are a better tweeter. That Denon may seem to work-but id be some easy on the volume dial

tonyb

The Denon is a receiver, not an amp, and is only rated at 90 watts. On the light side for 2b's imho. I don't see why Polk wouldn't ship some new tweeters to you. First though, I'd swap them into the speaker that is working and make sure it's not a crossover part that's keeping it from functioning.

mirceasy

Thanks bostopn1450 but the RD0194's will not require any alteration of the filter or crossover or they are just plug and play?
After reading some forums, I think that the broken tweeter can also be repaired. I don't know the exact english term but it's something to do with the coil, it's remade or something.
Any ideea which impedance value should a working SL2000 tweeter have?

tonyb

The RDO's are drop in replacements, no alterations to crossovers needed. However given their age, you may need to do some work on them anyway.

mirceasy

I don't know to much things about tweaking/reparing electronic components and carrying the SDAs to a specialist will require some effort.
The perfect option, from time efficiency and costs points of view, will be to repair the tweeter's coil, if this proves to be feasible.
Have any of you guys ever done this operation for the SDA's tweeters? does it seems doable?

Faustin

As Tonyb said.......the first thing to do is to swap the "dead" tweeter to the other cabinet and the "good" tweeter to the other to make sure it is the tweeter. Let us know how that goes.

RandyCroissant

There is a thread on here about tweeter dome replacement however as Tony states check the one you think is dead first you can check it with a meter or switch them. The best option would be to replace them with the RDO194 a drop in replacement tweeter that polk sells at a discount they sound better than the SL2000 that you have.

Rex81

I'm running my SDA 2Bs with a Crown XLS 1500. The XLS 1000 is in your budget brand new, puts out about 300 wpc at 6 ohms and is stable down to 2 ohms. It's a class D professional amp, but it runs dead quiet and sounds great.

I actually have some SDA SRS hooked up to my 1500 right now and even at very high volumes the amp is barely working up a sweat.

I highly recommend the Crown XLS line. Some people will scoff at them just because they're designed for professional use, but they're proven performers and because they're rolling out their new line, they're being liquidated for dirt cheap. Now, I'm not sure if you can get them where you are or not...

mirceasy

I just measured both tweeters and the specified one is dead. No value whatsoever after connecting the two multimeter pads on the tweeter (opposed to the other one).
I hope that it can be repared as I find the price of a new tweeters set very expensive, including shipment to my country (I paid for the SDA's approxiamtely 80 bucks).