trying to bi-amp...crossover adding too much hiss

[Tim Rinkerman]

Sorry about that...I missed a page of attempts...
Your pre-amp is probably running at-10 db. ( consumer level) output, pro crossovers are usually set up to see a signal more like +4 db. I think what you are hearing is a -10 db source with 14 db or more of operating noise added to it....kind of like trying to amplify a microphone level signal with a line level pre-amp.

[JBL 4645]

I was just thinking of KenWH where is he has he falling off the face of the planet?

I was wondering about the HF hiss issue as if I didn’t care, well I do! I was thinking what about wiring a passive crossover and use the woofer section to filter down the hiss.

Now this will change the characteristics of the tone when sending pink noise around so a little EQ might have to be applied to bring it back up.

This is hiss on that is mostly on the right HF is centred around 4 or 8 KHz I forget which, but I think its 4Khz.

[hjames]

Ya know, its pretty pointless to troubleshoot someone else's problem if he hasn't been here since January to give any feedback on people's previous suggestions ...

Can't be much of a problem if he hasn't asked for more suggestions in 9 months since this started ...

I was just thinking of KenWH - where is he? Has he falling off the face of the planet?
I was wondering about the HF hiss issue as if ...

[JBL 4645]

Ya know, its pretty pointless to troubleshoot someone else's problem if he hasn't been here since January to give any feedback on people's previous suggestions ...

Can't be much of a problem if he hasn't asked for more suggestions in 9 months since this started ...

Yeah maybe you’re right.

[KenWH]

Hi guys and thanks again for all the help in this thread. Sorry for not posting...I didn't fall off the planet.

It seemed the thread kept running into the same brick wall...gain structure...and I basically exhausted all adjustments I have. I just decided to live with it. A couple months ago I did add HSL -12db line level attenuators on the horn amp inputs which did help a bit but I'm far from statisfied.

My next step will be replacing the Denon receiver with a new pre/pro with balanced outs. I'm looking at the new Outlaw that's on the way(if it ever gets released).

I figure the "hotter" balanced signal from the pre/pro can only help with noise.

My other thought was to go ahead and having Marchand build me a passive 3ch. line level x-over as to eliminate all the sources of noise(op amps etc) within typical active x-overs.

Anyway thanks again guys!!!

[JBL 4645]

Hi guys and thanks again for all the help in this thread. Sorry for not posting...I didn't fall off the planet.

Well it was good simulation.

I see you Ken! Where in the blazes have you been in these past few months?

Have you solved he hiss issue?


Keep the level down on the output stages as it does produce a mild overload of sort at low frequencies.

Just amp up the level and test the LF and HF for a soft mild 75db use the amp to control the level, keep it soft you only need so much of it, too much and you’ll get that sodden his noise on the right channel 6 on the DCX2496.

Yeah get some amplifiers that you can adjust.

[JBK]

hi!!
My hifi system is composed by two 4675A, wich horns (2360A) have been removed, and I have put two IWATA horn instead. compressions are two 2450j, and as tweeters, two fostex T925A.
My amp is a MC7300, my preamp a C220, and my cd/sacd is a MCD301...
I've choosen to built a passive crossover...
(loudspeakers in the 4648 box are the 2226H)
The cutoff frequency is 500Hz, and the slope I've choosen 12db:
For the bass:
3,3mH, 31µF
Med/High:
10µF, 10,1mH, (att: 8db:R1=2x4,7 ohms, R2=8,2+2,2 ohms)

I find that's great!!!
Sorry for my language, I'm french!!
Regards, JBK

[KenWH]

Hi JBK

When I run the passive JBL 3160's the horns are very clean...barely any noise at all...the drawback I found was the woofers were crippled a bit. Running the speakers bi-amp'd gives me much better control over the levels. Now if only I can get the noise out of the horns when using active x-overs.

[Mr. Widget]

Hi guys and thanks again for all the help in this thread. Sorry for not posting...I didn't fall off the planet.

What crossover(s) are you currently using?

I think you summed it up when you said the hiss goes away when the active crossover does... it is still likely a combination of the crossover and gain structure. Virtually every active biamped system I have owned or heard has had some background hiss... then to add insult to injury this is always exacerbated by using high efficiency horn systems in small to medium sized quiet listening rooms... acceptable hiss in a stadium just doesn't work at home.

That said, I have always been able to get the hiss level down to where it was not noticeable at the listening position. You need a quiet crossover and diligently set it up... I believe from your posts you have exhausted the set up, so it would appear you need a quieter crossover. I doubt a new pre-pro will solve your problem.


Widget

[grumpy]

Maybe not the most efficient use of equipment, but why not use the passive
crossover for the horn and active crossover for the bass? (as was stated
earlier in the thread).

[Mr. Widget]

Maybe not the most efficient use of equipment, but why not use the passive
crossover for the horn and active crossover for the bass? (as was stated
earlier in the thread).

I'd give that a try... what's to lose? It should take care of the hiss and give you most of the control you want.


Widget

[JBK]

You're absolutely right when you tell that bi-amp allows a better control of the woofer...
The only thing which hold me back is money!!!!

For this reason, I have to wait... And I hate it!!
When I will be able to buy it, I will put a mac MC275 for the high and the mids, and my MC7300 will control the 2226 with strenght and ease!!!

The question I'm asking you is: What will sound louder in the horns? Active crossover, or tubes from the MC275?
One way or another, it will be better than tubes+active XO!!

A friend try to dismantle a passive crossover from an old JBL speaker... But it was full of resin!!! Impossible to see which values were used!! If you broke resin with a screwdriver, you will pulverize the components!!
When you've worked two years to build the ultimate XO, you don't want everyone to be able to make the same!! Clever idea!!

You're lucky to live in USA, there are a lot of cheap tubes amps to buy!! But in France, 230 volts forced us to buy it in Europe... Price is more more and more expensive, snif!!!!

Regards, JBK

[Egil]

Bringing up an old thread..

But here goes; Just like the op, I want to bi-amp some Waveguide speakers im currently working on, Im using a Behringer DCX 2496 as an active crossover.

• CD: BMS 4550 (driven by an Emotiva XPA-3: http://www.emotiva.com/xpa3.shtm )
• LF: JBL 2226H (driven by a Behringer EP2500)

There is a 33uf capacitator on the CD.

Here is a picture of how everything is set up:



I just bought the Samson S Converter, hoping it would take care of the hiss problem.. it didn't..


- When I turn off the DCX 2496, the noise is basically gone (you can hear some really low hiss. If I then turn off the Emotiva XPA-3, the noise is completely gone, naturally. So I assume that LOW-lvl hiss is caused by the Emotiva? If it was like that I would be more than satisified)

- There is noise regardless of where my AVR level is (maxed or off), and the noise doesn't get louder/lower when playing with the AVR level

- I tried plugging the DCX2496 and Emotiva XPA-3 in a plug with ground wiring - same noise

- I have even tried another DCX2496 (my brothers), same noise !

- I connected the CDs to the same speaker outputs on the EP2500, driving the JBLs, using banana plugs.. - I did this just to see if there was noise coming from the CDs with a PRO-amp as well.. I didn't play any music of course. The noise was still there..

- If I MUTE the CD on the DCX2496, the noise is still there !

- Btw, the noise is A N N O Y I N G ! You can hear it so loud & clear when im sitting at the LP 5m away.. im still able to enjoy music if I just crank it up a bit.. but I don't think I can live with that hiss.



After reading this thread, I can say that I haven't tried any attenuation (L-pad) of some sort, on the XPA-3. The Samson S-converter I bought seems to be a waste of money, - unless - I need to hook it up in a different way (Im going to try and hook it up from the Emotiva -> Samson Converter -> DCX2496).


EDIT: Problem solved!
I hooked up the Samson S-converter from the Emotiva-> DCX2496, and the hiss is pretty much gone!!!
I guess I was a bit too hasty

[lgvenable]

ground loop hum, use balanced connectors,
or
Behringer hd400 hum destroyers...they work.

[Guy in WNY]

Hi,
I use 3 Furman tx3 tuneable crossovers. The first is stereo 2 way and splits off the sub woofer from the rest. The rest goes to the other pair ,one for each channel, configured as a mono 3-way (LF 2x12", Mids 2350/2482, HF 2402). Very little hiss, but all equipment is in the 7' rack so I have the ground loop problems that cause hum. I used insulated washers to mount the amps, that helped a lot. Using Crown PSA-2 for subs, DC-300a Series II for LF, DC-300a Series II for Mids, and Marantz amp section for the 2402's.
Very little hiss, but the hum bothers me at times.
FYI
Guy in WNY