Simplexx 1x12 questions

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Grant Bunter
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Re: Simplexx 1x12 questions

#31 Post by Grant Bunter »

Many of Bill's designs are quite revealing!

While it may be unlikely the hiss is being caused by the cab itself, you should check all wiring and connections inside the cab to see if anything is loose or not that good a connection.

It is way more likely that the hiss is being caused by either the amp itself, the amps settings, or something upstream, and to work out what the cause may be, you need to walk through your entire chain.

Is it just bass directly into amp connected to cab?
If yes, check out your bass signal lead. Do you have a spare you can swap out to check?
Same for the bass itself, do you have a spare or a mate with a bass so you can plug that in, or see if it gets worse?
With the signal lead, if there is hiss with one, but not another, bin the bad one.
If you have hiss with your bass, but not your spare or the borrowed one, your bass has issues and needs a service.
If you can do that yourself, cool, if not, send it to a pro.

Is your amp's gain to high?
Turn the amp gain down and the master up and if the hiss goes, well, there's the answer.
Have you got the treble turned up? Or did you leave the settings the same as with your old cab (if you had one).
You might need to rebuild your sound from the ground up with a new cab.

If all these things check out ok, do you use effects pedals? If yes, remove one from the chain at a time, when the hiss goes, you found the faulty one.

All that's left if you've done all that, and you still have hiss, is that the amp is producing it. Get it serviced...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Bill Fitzmaurice
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Re: Simplexx 1x12 questions

#32 Post by Bill Fitzmaurice »

Verb wrote: Sun May 21, 2023 3:26 pm I am getting a fair amount of hiss from the tweeter, is this normal, or have I messed up somewhere?
Tweeters don't hiss. Electronics do.

Verb
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Re: Simplexx 1x12 questions

#33 Post by Verb »

Thanks for your replies.

I am getting hiss with just the amp connected to the cab, no bass connected. I still have hiss with the gain and master volume turned fully down. The hiss gets louder as I increase the master volume. I am getting the same results with both of my amps, a 90s Trace Elliot and a new Ashdown RM800, each has a new speaker cable.

As this is my first build I want to get it right. Is it possible the hiss is due to how I have assembled the crossovers?

Grant Bunter
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Re: Simplexx 1x12 questions

#34 Post by Grant Bunter »

Verb wrote: Mon May 22, 2023 12:14 am Is it possible the hiss is due to how I have assembled the crossovers?
Not likely.
Show us some pictures though, in case you missed something.

Does dialing down the L Pad change the hiss?
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

Verb
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Joined: Mon Sep 22, 2014 6:23 pm

Re: Simplexx 1x12 questions

#35 Post by Verb »

I will pull the crossovers out and get some photos when I have time.

Yes, the L pad acts as a volume control for the hiss.

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Bill Fitzmaurice
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Re: Simplexx 1x12 questions

#36 Post by Bill Fitzmaurice »

A mistake in the crossover wouldn't cause hiss. A cock up in the low pass might attenuate the woofer, making the tweeter more prominent. Tweeters, all drivers for that matter, don't create sound, they can only reproduce what's sent to them. Chances are you won't run the tweeter at more than 1/4 level anyway.

Verb
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Re: Simplexx 1x12 questions

#37 Post by Verb »

20230529_111748.jpg
20230529_111915.jpg
These are my crossover boards

I've rechecked the drawings and connections. I believe all is OK, but feel free to point out any errors.

I've searched online and it appears hiss is quite common when using tweeters, I've never had a cab with one before.

Thanks for all the help so far :D

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Seth
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Re: Simplexx 1x12 questions

#38 Post by Seth »

Can you tell me the values on the capacitors and coils in your high pass filter (second photo above)?
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

Verb
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Re: Simplexx 1x12 questions

#39 Post by Verb »

20230530_061105.jpg
20230530_060934.jpg
20230530_060900.jpg
20230530_060803.jpg

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Seth
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Re: Simplexx 1x12 questions

#40 Post by Seth »

Perfect. Looks all good to me.

The hiss is likely from the amps or possibly a dirty/corroded connection. Have you tried any contact cleaner in your jacks?

Also, just throwing mud on the wall.. it's usually a thing to try with hum after ground lift doesn't help, but worth a simple investigative experiment. Sometimes there can be something on a power circuit in the building that imparts noise, have you tried plugging the amps into other outlets in the house/building? Any change?
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

Bruce Weldy
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Location: New Braunfels, TX

Re: Simplexx 1x12 questions

#41 Post by Bruce Weldy »

Seth wrote: Tue May 30, 2023 9:36 pm it's usually a thing to try with hum after ground lift doesn't help,

Please....don't ever use a ground lift. The electronics nowadays are grounded and using a lift just opens you up to getting fried. If there's hum, it's most likely a signal cable ground somewhere that's bad. If I see a ground lift on my stage, I remove it or the player isn't playing....I'm not taking the liability hit.

Honestly haven't had a hum on stage in years that wasn't a bad mic cable (or a guitar cable). One show I was playing outside, I stepped up to the mic and got zapped. Got out my little tester plug and chased it back to a venue provided extension cord that someone had "fixed" and swapped the hot and the neutral. If something hums or you get shocked - there's a reason. Chase it down and don't take a chance with it.

Have one of these in your go bag....
https://www.walmart.com/ip/Receptacle-T ... 40997c0084

As far as the OPs issue - hiss won't happen from a grounding issue. Just needs to turn down the treble or do without the tweeter on a bass rig....especially if you aren't playing music that needs that on the bass part.

6 - T39 3012LF
4 - OT12 2512
1 - T24
1 - SLA Pro
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

Verb
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Re: Simplexx 1x12 questions

#42 Post by Verb »

Thanks for the help guys.
I think the hiss is probably just normal hiss, created by my amps.
Having not had a cab with a tweeter before, I was surprised and concerned about it.
As Bill said, I probably won't run the tweeter very high, so I will live with it.

Verb
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Joined: Mon Sep 22, 2014 6:23 pm

Re: Simplexx 1x12 questions

#43 Post by Verb »

Me again 🤣

I haven't been happy with the sound of my cab, it lacks low end and sounds nasal.I originally intended to build two 1x12 cabs so have a spare 3012HO.
Connected full range straight to the jack , I feel there is noticeable improvement. My concern is that I have somehow damaged the original woofer.
Due to the small size of the connection tabs on the speakon connectors, I didn't attach jumper wires from one jack to the other. I connected one wire to each tab and then split from this wire to the crossovers, I have attached a diagram showing how the connections are made. I believe this is electrically the same, but wanted to check before I connect the crossover to the new woofer.

Once again, thanks for all your help
20230629_145455.jpg

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Bill Fitzmaurice
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Re: Simplexx 1x12 questions

#44 Post by Bill Fitzmaurice »

I don't know what that diagram is showing, but it's not what the wiring should look like. I suspect the crossover is incorrectly wired.

Verb
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Re: Simplexx 1x12 questions

#45 Post by Verb »

Sorry for my poor diagram.
The +1 and -1 are the connections on the speakon sockets and the wires go to the crossover inputs.

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