Will reversing the polarity of drivers/tweeters work for inverted preamp with sda2a's

taylormade

I'm looking at purchasing a tube preamp, but most or inverted polarity to save a gain stage. I found a discussion on this, and it was said this would work, was just wanting to verify it since Polk hasn't gotten back to me yet. Polk only has certain people that know anything about sda's.

[Deleted User]

Reversing the polarity at the speaker connection will work for the majority of speakers, but not for SDA type speakers. Unfortunately this would connect the left and right positive terminals of the amplifier to a short (in the case of a twin blade SDA speaker) or no sound at all (in the case of a pin blade SDA speaker).
If you have a preamp that inverts polarity you can find a matching power amp with an inverting output which will put everything back in the "correct" polarity. Or, if your primary listening source is playing records, swap the leads on the back of the phono cartridge (except for Decca owners).
Or, add a "buffer" which is usually a cathode follower stage which will re-invert the polarity.
Or, just don't worry about it. Historically a very small percentage of people seem to be "tuned in" on this kind of change. Compared to other major areas of audio concern it's like worrying about a leaky faucet on the Titanic. If everything else was water tight then it would merit getting out a wrench.

tonyb

Good analogy Ken, lol.

Personally, I've heard little to no difference on my tubed pre which is supposed to be reversed polarity. I wouldn't lose sleep over it.

pitdogg2

KennethSwauger wrote: »

Or, add a "buffer" which is usually a cathode follower stage which will re-invert the polarity.

Are you referring to a tube buffer device here Ken?

Agree with Tony great analogy there Ken.

stones89

Ken, you answered this question for me in 2000 on a PM. I still have the e-mail…. LOL!

I have a phase button on my phono preamp and can hear no difference. An album or CD can vary whether it is in absolute or inverted phase from track to track from the various steps of the recording process. Personally, I do not sweat it and can't tell the difference anyway.

[Deleted User]

Yes, a tube based buffer will work to get the polarity groove back.

taylormade

Thanks for the input everybody. I may not even hear the difference, I was just thinking if I did I could just swap the wires on the drivers and tweeters, that that would work. I'm sure in the 30 years I've owned these speakers I have reversed the polarity on the drivers by accident before with no I'll effects. I just rebuilt the crossovers and TL'ed the tweeters circuiper westmassguy. Leaned a lot reading this forum much appreciated.

msg

Ken, wow. That is some seriously intimate knowledge with the SDA design.

taylormade

I just followed westmassguy's posts on the forum and I'm glad he took many pictures that helped a lot. The only hard part was figuring out which resistor was which on the circuit board, because I already had all the sonicaps and link resistors installed ( TLing them was an afterthought). They sound better than they ever have, and I bought them new in 87. I'll post some pictures of them later this week. My friend painted them piano black at the auto body shop. They look fantastic.

F1nut

taylormade wrote: »

Thanks for the input everybody. I may not even hear the difference, I was just thinking if I did I could just swap the wires on the drivers and tweeters, that that would work. I'm sure in the 30 years I've owned these speakers I have reversed the polarity on the drivers by accident before with no I'll effects. I just rebuilt the crossovers and TL'ed the tweeters circuiper westmassguy. Leaned a lot reading this forum much appreciated.

Reversing the polarity on the drivers will affect the bass response.

westmassguy

I would think inverted polarity by the pre would have no effect downstream, as long as the power amp is common ground for the 2As. Power amps are dumb as far as I know. They don't care if the input signal is inverted or not, they just amplify it.
To the OP, the high-pass section of the 2A, 2B, and 87'-89' CRS+ are essentially Identical (except for the shunt resistor in the 2A). You're just adding the 5.8uf Cap in the same location on the 2As. This forms a contour network, which compensates for the RD-0198's frequency response, which differs from the RD-0194's.

[Deleted User]

In an ideal situation as the leading high pressure sound wave reaches the microphone's diaphragm it would generate a positive going voltage with respect to the microphone's ground. Here again in this ideal recording studio this positive voltage would be maintained throughout the complete process and remain positive until it reaches your record, CD, tape, radio signal or digital download (in the future it will probably impact directly into your cerebral cortex). In turn your ideal sound system will move your speaker's diaphragms/cones outward towards the highly enlightened listener. This would maintain the transient pulse's intended wave front, which is a good thing. To people who are more sensitive to this than others they report that, to them, one way sounds more like they are in front of the music rather than behind.
In my semi-humble opinion I believe this is more relevant to owners of full range electrostatic speakers than moving coil type speakers. The transient accuracy of a well made electrostatic speaker reveals more of the results of absolute polarity.

littlewoodboats

Could the polarity be switched back using a custom made interconnect between the pre and amp? From what Ken wrote it would not seem to matter, I was just curious.

[Deleted User]

Unfortunately that wouldn't work since it would happen at a "single ended" connection. It would have to be done at a "balanced" part of the audio chain, such as the back of a phono cartridge or a tape playback head or any true balanced cable. Somewhere the audio signal is represented by two separate yet equally important* conductor paths.

(fans of "Law & Order" will get that reference)*

westmassguy

littlewoodboats wrote: »

Could the polarity be switched back using a custom made interconnect between the pre and amp? From what Ken wrote it would not seem to matter, I was just curious.

If the Pre and Power amp used Balanced Connections, either XLR or TRS, theoretically yes. Most consumer gear uses Unbalanced RCA connectors, which usually share the chassis ground with the outer shield of the 2 conductor cable.

analogluvr

KennethSwauger wrote: »

Reversing the polarity at the speaker connection will work for the majority of speakers, but not for SDA type speakers. Unfortunately this would connect the left and right positive terminals of the amplifier to a short (in the case of a twin blade SDA speaker) or no sound at all (in the case of a pin blade SDA speaker).
If you have a preamp that inverts polarity you can find a matching power amp with an inverting output which will put everything back in the "correct" polarity. Or, if your primary listening source is playing records, swap the leads on the back of the phono cartridge (except for Decca owners).
Or, add a "buffer" which is usually a cathode follower stage which will re-invert the polarity.
Or, just don't worry about it. Historically a very small percentage of people seem to be "tuned in" on this kind of change. Compared to other major areas of audio concern it's like worrying about a leaky faucet on the Titanic. If everything else was water tight then it would merit getting out a wrench.

I ran into the same issue and I can attest to the fact that it is very very noticeable! It's bizarre the vocalist is very far away and the Soundstage curves around you on both sides. With ordinary speakers it's not overly noticeable but for me it was unlistenable with the SDAs. I'm curious about this because I just have not been using my favourite preamp due to this fact

analogluvr

Maybe we should start a thread listing amps that reverse polarity.

analogluvr

And when I tried to reverse the polarity back at the speaker terminals the dimensional drivers didn't work properly. So as I said I pulled the pre.