No-amping SDA speakers.
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Rocketmanlynn
Posts: 20
F1nut. I lay here in the middle of the night sleepless thinking of the hours spent lately reading thread posts here and else where. I have two pairs of SDS speaker both bought new; a pair of 1.2TLs R6391 L6371; and 3.1TLs 2156R 1664L I have for a while in my new large audio HT room (24’x33’) seriously contemplating how to set up my 1.2s each bi-amp with 2 bridged Adcom 555IIs (of the six that I own). I have the original interconnect cable. After reading about the Common ground issues with this kind of setup and the need possibly for a dreadnought. This is all new to me and more than a little unnerving. My goal in all this is to enjoy, listen to my Polks at the best possible performance, I can provide. I understand that the easy option and simplest solution to my quandary is to drop it. Knowing myself, I will take the easy road after I have broken an axle first on the road. My question finally to you. Can you suggest a route to follow, specific things to do, buy, and the information to follow, so I can make this happen?. I’m going to obtain and follow the necessary steps outlined in threads here to upgrade first the 1.2s then the 3,1s. As a new person to the forum with vintage speakers you see and here the same subjects and requests over and over. I get it, I do. But you wouldn’t be who and where you are, if this wasn’t your passion and what you wanted to do. Yea, It’s a hobby, like all hobbies if isn’t fun don’t do it.
Best Answers
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Having owned a pair of 555's in the past I would recommend using a single 555 as I was not a fan of the bridged adcom sound on any speaker I paired mine with. I also tried vertical bi-amping them on my Polk 2.3s but I didn't feel I gained anything as a single 555 is plenty robust enough to run the 2.3s full range. They will run a 4ohm load bridged but they'll only be seeing 2 ohms and will get hot!
Better yet imo is to use them as a down payment on something much better. Their age and lack of dc protection is a liability you may want to take into consideration. -
Maybe I didn't make myself clear. IF you want to bi-amp your speakers and not have the common ground issue that would require the AI-1 or Dreadnaught. Hook one amps L & R channel to the tweeter (top posts) L & R of each speaker. Hook the other amps L & R channel to the L & R driver (lower posts) of each speaker. One amp is driving only the tweeters and one amp is driving only the drivers.
Using one amp per speaker is IMHO only best if the amps are true mono amps AND you use either the AI-1 cable or the Dreadnaught.
As for upgrading your speakers, I would make that a priority. There is a great improvement to be had there.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
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Bridged amps bring more noise to the table and usually dislike anything lower than 8 ohms.
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Thanks pd2. I’ve read your comments and posts on several subjects, so I trust your experience and advice. I don’t have an electronics background so unfortunately I’m left learning by T&E. I don’t know, what I don’t know, until the smoke signal go up. I’m trusting you old dogs will keep me out of that kind of trouble. I’m using Adcom equipment and Polk products that are widely known and this has all been tried before by much smarter guys than me. I know what I like, I hope to discover what’s an improvement and what works by hearing it. Keep the comments coming. I have a very thick skin.
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Does bi-amping this way affect the speakers impedance? I know there an issue with the amp’s common or not, grounding that can’t be discounted. I don’t understand exactly how that works. I’m read up on this through the forum.
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You're not bi-amping, you're essentially using mono-blocks. Yes you're using two amplifiers but one to a speaker. The amp in no way affects the ohm value of the speaker. If your speaker is a 4 ohm speaker then most amps in bridged mode with a 4 ohm speaker dislike the load presented. More noise, more heat etc.
Bi-amping is more than one amp per speaker. -
Ok, I see. Bi-amping would be driving half the speaker with left channel the other half the right channel of a single 2 channel amp? How does the relate to bi-wiring?
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Rocketmanlynn wrote: »Ok, I see. Bi-amping would be driving half the speaker with left channel the other half the right channel of a single 2 channel amp? How does the relate to bi-wiring?
Here's what I think they mean. Others can correct or embellish.
Bi-amping is feeding each speaker from two amp (or independent channels). One to the low frequency input and the other to the high frequency input while removing the strap or jumpers that connected the two before. Works best when you have a external crossover separating the signals before the pair of amps and amps sized for the power requirements of the frequency range they are driving. Think of this as if you had individual speaker cabinets for each set of drivers and each was it's own "channel"
Bi-wiring runs a parallel set of wires from the amp output to the speaker inputs. In simple concepts same as running a bigger wire to the speaker and driving both crossover inputs from the same amp.
Third case you might see is integrated jumpers where the speaker end has two sets of connectors. This would replace or be in parallel with the shorting bars between the speaker inputs to it's crossover. Much like the bi-wire above but less wire.
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Hey thanks. I’m a visual person if I see it, I get it. Your explanation is great, until the next commenter thinks your full of whoey. What kind of car are you pictured in, l’m a car guy.
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That's my 91 Mitsubishi Eclipse GSX on the way back from the Factory in Normal, IL. It doesn't see much use anymore.
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Paragraphs, @Rocketmanlynn -- paragraphs.
I felt like I was reading Kerouac's On the Road or something...
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By the crib notes
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That's my 91 Mitsubishi Eclipse GSX on the way back from the Factory in Normal, IL. It doesn't see much use anymore.
NICE I live not too far from that factory.... I know who sold the land for that factory
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Rocketmanlynn wrote: »By the crib notes
Well played, sir (or ma'am, as the case may be) -- well played.
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If you want to bi-amp your speakers then use one amp to run the tweeter array of both speakers and the other to run the driver array. As for upgrading your SDA SRS's, go here: https://forum.polkaudio.com/discussion/133384/all-the-polk-sda-upgrades-located-in-one-place#latest
Welcome to the forumGustard 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 -
I believe I get it. I will have to try it. Does the common ground issue come into play with the amps only if they’re bridged? My original forum question which was partially answered is this is: (the reader’s digest version for those so challenged) I have planned to use 2 M10s end to end as a center channel. Should I bridge the amp and wire the speakers in parallel (800+ watts at 4 ohms) or drive each speaker with the left or right channel in mono, 200 watts at 8 ohms? Dealers choice.
Fast cars hot audio gear. -
I dread taking my sda’s apart. But no guts no improvement. I understand I have to remove the speakers to gain access to the crossover etc to make changes.
I believe it is better have spent all your money on expensive stereo gear, than to have ever collected stamps as a hobby.
