Out of the game for years and in need of a new amp for my SDA SRS speakers.

audioluvr · September 9

Without upgrading your speakers, you probably won't know if upgrading your amp/pre was much of an improvement. As speaker crossovers age they tend to get a muddy sound depending on the amount of use/abuse. If you need help with a DIY crossover upgrade there's a lot of previous discussions that can help train you and a bunch of very knowledgeable members who would be happy to help with advice.

Welcome to Club Polk.

agfrost · September 9

F1nut wrote: »

Musical Fidelity Nu-Vista 800.2.
Current - 120 amps peak to peak

'Nuff said

Musical Fidelity will deliver the current. Specs on my A5cr power amp--Sadly it's sick and needs medical attention.

motorstereo · September 9

^^^^^^^Wow I guess that A5 will deliver the current! That's the same amount of current as my Mcintosh mc1201's.

F1nut · September 9

The Musical Fidelity Tri-Vista kW mono block amp specs always impressed me. Unfortunately, they were out of my price range.

Output voltage, RMS 92 Volts 20Hz to 20kHz peak 130 Volts

Power output, single or both channels driven 1000 Watts per channel into 8 Ohms (24dBW)
1800 Watts per channel into 4 Ohms
3000 Watts per channel into 2 Ohms

Peak output current ± 200 Amps

Damping factor 205

Output devices per channel 40

Total Harmonic Distortion + noise 0.005% at 1kHz up to 80% power, into 8 Ohms
< 0.005% 20Hz to 20kHz at 12.5 Watts into 8 Ohms

Gardenstater · September 9

I assume that peak current would be into the lowest rated impedance of 2 Ohms?

If so that is about 4.3x the calculated current of 32.6 Amps for 3000W into 2 Ohms with 92 Volts.

200 Amps / sqrt(2) = 141 Amps RMS. 3000 W / 92 Volts = 32.6 Amps. 141/32.6 = 4.3x.

Calculated another way from Power = Current ^2 times Impedance, would give Current = sqrt(3000/2) = 38.7 amps. 141/38.7 = 3.6x. Which is right?

Whichever is correct, that is inline with a paper I found that says that peak current with musical signals can require 3 to 6 times the calculated value from rated voltage and impedance.

https://assets.ctfassets.net/4zjnzn055a4v/3IoTVSUR2LWt9wA9v5JfyF/ab19bb84e1cfe5c0b95c4b1b901b680b/Input_Current_Requirements_of_High-quality_Loudspeaker_Systems.pdf

daddyjt · September 9

F1nut wrote: »

The Musical Fidelity Tri-Vista kW mono block amp specs always impressed me. Unfortunately, they were out of my price range.

Output voltage, RMS 92 Volts 20Hz to 20kHz peak 130 Volts

Power output, single or both channels driven 1000 Watts per channel into 8 Ohms (24dBW)
1800 Watts per channel into 4 Ohms
3000 Watts per channel into 2 Ohms

Peak output current ± 200 Amps

Damping factor 205

Output devices per channel 40

Total Harmonic Distortion + noise 0.005% at 1kHz up to 80% power, into 8 Ohms
< 0.005% 20Hz to 20kHz at 12.5 Watts into 8 Ohms

This also puts out 200 amps🤣🤣

treitz3 · September 10

I have the little brother to that amplifier (KW-750). It has plenty of power for me, it's powerful enough that I would struggle to ever reach the amount of power needed to max out on her. I was reading a review of the mono block amps a few years ago, and the reviewer stated that he would be afraid to use it as his reference because if he ever dropped the needle on his TT? He feared that he would have blown his speakers.....or something to that effect.

Tom

Jstas · September 10

If sticker shock is not your bag but you want big, clean power at an affordable price, New Audio Dimensions (NAD) has a few amplifiers and integrated amplifiers that I have had great success with when powering SDAs. I'd put them on par with the Parasound amps that others are talking about.

The NAD C399 integrated everyone seems to love and it packs a big punch at 180 watts per channel and has a pretty good integrated DAC too.
https://www.crutchfield.com/p_745C399/NAD-C-399.html

And if you just want an amplifier the NAD C298 puts out 185 watts per channel of grunt and it'll happily drive your heaviest loads all day long without complaint. It's capable of handling any of the SDA models too.
https://www.crutchfield.com/p_745C298/NAD-C298.html

Every NAD I've ever used punches above it's weight class and they are good value for the money. They pair well with SDAs too as I've heard them on my SDA 2Bs, a pair of CRS+, SRS 2.3TLs

You can pick up good NAD used/vintage gear that is going to be just as solid as their new gear too and the used market can make getting a high dollar piece of gear much more affordable.

F1nut · September 10

treitz3 wrote: »

I have the little brother to that amplifier (KW-750). It has plenty of power for me, it's powerful enough that I would struggle to ever reach the amount of power needed to max out on her. I was reading a review of the mono block amps a few years ago, and the reviewer stated that he would be afraid to use it as his reference because if he ever dropped the needle on his TT? He feared that he would have blown his speakers.....or something to that effect.

Tom

I've heard or owned a number of MF gear. It doesn't matter the model, the best description of their sound is sublime and doesn't get any better than that.

richdel · September 11

As a matter of keeping my facts straight that I have shared here with you, with the help of F1nut, he has definitively identified my speakers as sda srs 1.2's. I had originally thought them to be sda srs's. You all have given me so many things to look at that I might never have known had I not come here, so thanks a lot for that.

It looks like my previous estimated budget may get blown out of the water, although I am going to look at some pre-owned equipment and prices. If there are anymore suggestions regarding power amps or integrated amp that pair well with the sda srs's, I'd be grateful if you let me know. Thanks again for the help!

Jstas · September 11

If you are looking used, Adcom amps, while often described as "sterile" are inexpensive on the used market and are more neutral than sterile. You can find some serious powerhouses from Adcom that will drive a set of any SDAs all day long.

Pair an Adcom amps with a tube based preamp you'll be in for a treat t bargain prices.

michaeljhsda2 · September 11

richdel wrote: »

As a matter of keeping my facts straight that I have shared here with you, with the help of F1nut, he has definitively identified my speakers as sda srs 1.2's. I had originally thought them to be sda srs's.

Since they are confirmed 1.2's the positive (red nuts) should be on the left and negative (black nuts) should be on the right. Chances are the label on the back probably shows positive on the right as that label is a leftover from the 1st gen SRS where positive is on the right. From a previous post regarding this issue.....

Polk was known to use up old stock during their production on a lot of their speakers, so that is a label that was left over from the 1st generation SRS which has the positive on the right! The SRS 1.2 and SRS 1.2TL models have the positive on the left! Why did Polk make that switch? Who knows but in every instance over the years that I've been on this forum, this issue has been brought up and every 1.2 owner has that wrong sticker on the back of their speakers. As a result, they have been unwittingly listening to their speakers out of phase! Not sure if Polk ever knew about this error, but if they did it would have been nice for Polk to notify the dealers and send out a sticker to put over the wrong one and switch the plastic positive and negative nuts to the correct location...

Here's a link to the thread.

https://forum.polkaudio.com/discussion/201029/sda-srs-1-2-reversed-polarity/p1

F1nut · September 11

Excellent point and I can confirm the OP has the red posts on the right.

Rich, remove the binding post plate (4 screws) to observe what color wires are connected to the red posts, report back please.

richdel · September 12

F1nut wrote: »

Excellent point and I can confirm the OP has the red posts on the right.

Rich, remove the binding post plate (4 screws) to observe what color wires are connected to the red posts, report back please.

Thanks again for all the insight. Like you stated red was on the right, and black was on the left. Here are the pictures I took after removing the bindings plate.

michaeljhsda2 · September 12

Everything is wired correctly so no need to change anything.

richdel · September 12

Awesome, thanks again for your help.

michaeljhsda2 · September 12

You're welcome, enjoy the journey.

michaeljhsda2 · September 12

Are you going to convert them to TL's?

richdel · September 12

michaeljhsda2 wrote: »

Everything is wired correctly so no need to change anything.

Sorry, but I do need to test for my own understanding.
Fact, my speakers are SDA SRS 1.2 and are NOT SDA SRS's, correct?
Fact, the sticker on the back of my speaker misrepresents how the wiring should be done, but the wiring inside of the plate shows the wiring was changed to what it should have been, correct?
Fact, as they are now SDA SRS 1.2 speakers that ae wired correctly, if I purchase a "dreadnought" or appropriate interconnect cable, I should be able to run monoblock amplifiers without damaging my speakers or amplifier, correct?

Sorry if I seem thick, but the last few days I have been saddled with a bad cold that I have been trying to mitigate the symptons with cold medicine that has made my line of thinking cloudy and at times not logical.

pitdogg2 · September 12

Fact, as they are now SDA SRS 1.2 speakers that are wired correctly, if I purchase a "dreadnought" or appropriate interconnect cable, I should be able to run monoblock amplifiers without damaging my speakers or amplifier, correct?

YES ! You should build a dreadnought whether or not you decide to use a non-common ground or monobloc. The dreadnought works on common ground stuff too, mo'better.
Polk was very well known to use old stickers on speakers when they moved on to new models, they were "thrifty" in that way.

michaeljhsda2 · September 12

^^^this^^^ and get well soon. No doubt about it you have 1.2's because Polk never made a first generation SRS with a pin blade interconnect socket. You have the only pair that I have seen where Polk wired them correctly from the factory even though the label is a blade blade sticker for the first generation SRS.

richdel · September 12

michaeljhsda2 wrote: »

Are you going to convert them to TL's?

So I know I can read/research what the machinations are to go from a 1.2 to a 1.2tl, but is it just as simple as replacing the tweeters or are there other components that need to be upgaraded/replaced (namely crossovers and associated electronics) in addition to the tweeters? I still intend to read about the process, just looking for the "cliff notes" version right now so I can stay focused on target with my initial quest. I got so many new avenues to pursue right now that it almost seems overwhelming. BTW, I just listened to the Whisper Sessions - Melissa (feat. Derek Trucks) by Warren Haynes on Spotify (non-lossless, I wasn't lucky enough to be one of the early premium members to get moved to lossless) using my current system, Spotify connect->Sony strdh590 a/v receiver-> polk sda srs 1.2 and it sounded so darn good, that it made me excited to hear it with new and updated equipment.

pitdogg2 · September 12

When you upgrade the XO upgrade to the TL XO and buy 8 RD0-198 tweeters. IF you plan on that just buy the tweeters now, call Polk CS mention you're a member here and get a small discount on the 8 or 10, never hurts to have a spare or two.
I think I have 6 spares

michaeljhsda2 · September 12

Correct, updating the crossovers and replacing the tweeters as stated above. In addition, the negative wire that attaches to each tweeter will need the quick connect changed to a larger size to fit on the tweeter post since it is larger than the positive. Then you'll need a Molex pin removal tool to reverse the polarity for each tweeter where the Molex connector attaches to the crossover board.
If you order the tweeters through Polk mention that you are a forum member and I believe you get a discount and free shipping but don't quote me on that as it's been a long time since I ordered from them. Part number for the tweeter is RD0-198-1 if ordered through Polk. That's a zero, not an ohh. If Polk no longer sells the tweeters, Midwest Speaker sells them and part number is RD0198-1

https://www.midwestspeakerrepair.com/product/polk-audio-sl2500-sl3000-1-inch-dome-tweeter/

F1nut · September 12

Other than changing the tweeters there are quite a number of changes to the crossover involving resistors, caps and inductors. The schematics are posted on the forum for your viewing.

odcics2 · September 13

Great deal on ebay- Parasound HCA-1200 II
It does 315 wpc at 4 ohms. John Curl designed.

https://www.ebay.com/itm/146817032060?mkevt=1&plmtId=1110700101&mesgId=3014&mkpid=0&emsid=enull.m161719.l174380&mkcid=7&ch=osgood&euid&bu=43191925568&trkId=f37b5dc2-d66a-3029-9902-1d2539271efa&cnvId=29f8e0f4-fcbc-4b3b-8055-f5fe3c8c9490&osub=-1~1&crd=20250913033200&segname&recoId=146817032060&recoPos=1

richdel · September 13

Thanks!

richdel · September 16

Thought I would update a bit on where I am currently at in the search. At this time, I am thinking about the Parasound Halo A21+ (used) or A21+ (used). Along with the Eversolo dmp-A8 as my DAC/Streamer/Preamp. Both of them new would set me back around $6k. Don't have that available for this upgrade. I was originally at $3-3.5k when this started. I have expanded my available cash some, but not to a $6k pricetag. Since the ES dmp-A8 is relatively new, there is very little on the used market. So I am hoping to find a used A21+ and a new A8. Depending on the price of the used A21+, I might be able to make this work. In the meantime, I continue to read and research and try to get caught up with current offerings. If there is something to add, please let me know. Thanks!

pitdogg2 · September 16

A Parasound A21+ would be an excellent amp to have.

skipshot12 · September 23

Parasound A21+ just came up for sale on Audiokarma.

https://audiokarma.org/forums/index.php?threads/parasound-a21-stereo-power-amp.1093979/

Out of the game for years and in need of a new amp for my SDA SRS speakers.

Answers