SDA SRS's dropping top end at relative high volume level

tratliff

Hi SDA SRS owners,

I am building out my 2 channel system and have acquired a pair of SDA SRS's. They are in great shape. My dad owned them since 85 and I know they have not been abused. I am beginning to have a problem at high volume levels where it appears the high frequencies drop out. First I noticed it in the right speaker and last night the left speaker did the same. I am powering them with a Parasound Halo A21, which is rated at 250/400 wpc 8/4 ohms. Everything in the speakers is original. No mods. When this happens, simply turning the volume down to a fairly low level causes the highs to return.

Has anyone else experienced this?

Is this a symptom of a 30 year old x-over? Is it time for an x-over rebuild?

Thanks for the help.

pitdogg2

turn it down you are tripping the poly switches. Poly switches protect the tweeter section as you are finding out. they do go bad from repeated tripping which means that they will trip easier. You could replace with new they are stocked at Parts Express. Most of us have removed them and replaced with a .5 ohm mills resistor but then you cook tweeters if you do not know your limitations.

Mr. Bubbles

^^^^^ What he said ^^^^^

tratliff

Thanks for the feedback. I'll check out the poly switches.

Mr. Bubbles

Oh, and welcome to the forum.

zingo

You can all call Polk Customer Service as I believe they will send you a new set.

tratliff

Thanks for the Welcome and quick responses.

Jake - that’s awesome to know that Polk will help.

I’m sure this won’t be my last question. I really enjoy surfing the net for information when I get on a project. Kind of OCD. Some of you probably understand.

Thanks again

tratliff

Jake was right. Made a call to Polk and the Poly Switches are on the way. No charge. Great service.

So, as I said, I now have my next question to the guys who have replaced these. What is the best way to access these? And where in the cabinet are they located?

Thanks

F1nut

You shouldn't think that new polyswitches will be the absolute answer. While it is possible, even highly likely, that yours have become hypersensitive it's also likely that you're pushing the amp into clipping. What was the position of the volume control when the polys kicked in?

They are located on the crossover board, which is mounted to the metal panel on the front bezel.

Moose68Bash

tratliff,

Welcome to the Forum. I'm also relatively new to this Forum. I don't know how deeply you plan to delve into updating your SRSs and I don't know how much know-how you have with respect to modifying them yourself. But, I can tell you that the guys on this Forum are both deeply knowledgeable and incredibly generous in sharing their knowledge and experience. You can do as much or as little as you want and as you can afford and at your own pace, and they will advise and help you all along the way. I'm just commenting based on my personal experience.

One indispensable resource is the "SDA Handbook," which is now, I believe, in its third revision and which was largely composed/assembled by DarqueKnight of the Forum. It is available for download on the VR3 Mods Web site. This handbook contains a wealth of information about the gems your father has given you and also lays out information about mods you can do to bring them into the 21st century.

There are also numerous threads that document and explain step-by-step mods others have done and have proven to be worthwhile investments in their SRSs.

Again, welcome to the Forum. You will find this a great place to be!

tratliff

Thanks guys. I am just getting started with these speakers and would love to make the mods. Time and money will play a significant role in that. I guess I'll take it one step at a time. For now I'll keep an eye on my "need for volume" and replace the poly's hoping that they provide some relief. I will also read about the upgrades on the site and start to plan for the next phase of mod's.

leftwinger57

F-1 ,Jesse you possibly implied tratliff might be clipping w/ his amp.Tratliff says he has a Parasound that is rated per watt stronger than my Adcom 555 by 50 watts a side.Playing d/advocate here I can't even go over my 10 pos on my pre w/o it starting to hurt.Now we all know I had my own clipping problems w/ my avr which is an entirely different animal.I understand 2bs and SRS are 2 different speakers and then there is different strokes for folks but at the level of that volume must be insane.I'm sure 1 must consider room size and all other factors and have no knowledge of said poly switches but i sure know loud when I hear it.
Tratliff --as a fairly new owner of 87' SDA 2bs take advice from these guys.I am in the process of doing mods and improving on a sound that I thought was impossible to improve on .

tratliff

Yep. Not sure I was clipping the amp. The preamp, a Parasound Halo P3, has a digital volume control. Not sure how to rate that but from what I understand the range is indicated on the front with values ranging from 0 - 80. 80 being max. When the high frequencies were shutting down I was in the mid 50's. So I might equate that to about 12 - 1 o'clock on a normal volume knob.

F1nut

So I might equate that to about 12 - 1 o'clock on a normal volume knob.

At that point you are most likely overdriving the amp. General rule of thumb, keep it under the 12 noon position.

leftwinger57

Tratliff, just out of curiousity what is the room size your listening in.Mine is 18'x15'.....And yes that's got to be very loud.

nspindel

Probably overdriving your ears as well!

zingo

nspindel wrote: »

Probably overdriving your ears as well!

Could be. I only listen to my SRS 2 with 400wpc with the volume at 10 o'clock on my no-gain preamp.

tratliff

Room is about 20x17. Dont get me wrong it is what i would consider "pretty" loud.

PolkieMan

Everyone at this price should have one of these

http://www.parts-express.com/pe/showdetl.cfm?partnumber=390-722

tratliff

Just wanted to get an update out. I received the poly switches from Polk. Have not had a chance to install them but have been enjoying the new combination of components over the last few evenings...And having some volume control, although it’s difficult. Wow, these things sound great with the new Halo A21 amp and Halo P3 pre. The reserve power of the Halo A21 has really opened up the dynamics. This is a great improvement over the Pioneer SX-1250 I was originally powering them with. I have now pushed the SX-1250 to tuner duty. I’ll get an update out after the install of the poly switches. Thanks for all the advice.

michaeljhsda2

Congrats on the new gear. I'm quite content with my integrated tube amp but on the other hand I'm doing all I can to resist buying a Parasound Halo A21 amp and P3 pre. Did you buy new or used?

tratliff

Got them used off DFW craigslist. Nice find. The guy I purchased from has additional A21's for sale.