Problem with L300

[Tom Loizeaux]

If you can be a little more clear about what problems you are hearing, maybe we can help you find the problem and get these working properly. Explain in more detail what you mean by "boomy bass", etc. The more detail you give us the better able we will be to help.
Please keep giving us information.

Tom Loizeaux

[boputnam]

Hey, Widget....

Now I'm confused !!

If this is the 4333A, maybe the bi-amp switch is IN, and needs be OUT to use the internal crossover?

Hey, bondu !!

Rotate that little screw at the base of the crossover to the left (<-- ) to "INTERNAL CROSSOVER".

[scott fitlin]

can it be that the L300 is an impedance mismatch for those OTL tube amps? Tube amps were known to be finnicky and load sensitive. If it is an impedance mismatch it would cause the frequency abberations described! Especially if the OTL amp has a high output impedance.

Just a thought!

[Mr. Widget]

Tom is right we need more info.

Bo, you have a point, it could be operator error with the crossover.

Scott brings up a good point. It could be an amp issue.

[boputnam]

boudu...

"mine are the same of the 4333 with bi-amp possibilities"

and your first description got me to thinking - you may have the crossover set to EXTERNAL CROSSOVER, and for your set-up it needs be INTERNAL CROSSOVER.

Here's a picture that looks set to INTERNAL CROSSOVER.

You should connect to only the lower binding posts.

Any luck??

Ha! Maybe you can't hear us anymore - you're dancing!!

[lpd]

Yes, I have made the mistake of having the bi-amp switch on external crossover, and fortunately didn't damage anything because the horns were not wired Make sure the switch is set to internal crossover.

Do you have any sound from the horns/tweeters? How is the output matched to the bass drivers? Perhaps the l-pads need cleaning.. I replaced both the tweeter and horn l-pad and it made a huge difference in both the tweeter and horn its like they came alive.

I run my JBL's on an Acoustat TNT200 and a Dynaco 70 sometimes. Sounds great on the tubes. Not as much headroom but the midrange is to die for (can't wait to listen to the 4343's)!!!

Good luck and keep us posted!!

[scott fitlin]

i could see JBL midrange drivers sounding fantastic on a low power tube amp. JBL drivers for mids are very efficient!

A bi amp combo of SS for the lows and tube for the mid/high should really knock someones socks off!

[MikeM]

Afyer being used to the klipchkorn the L300 will ne a major change in sensitivity! What cond are your output tubes Good you say?.Well the L300 has a nice current hungry woofer. Not ineffecient but still you will benifit from lowend grip ot solid state for lows Bring the L300 about 4 foot from the rear wall. You want to isolate this speaker from the room as much as possible. Why didnt you like the corner horns? Enjoy you L300 they are FANTASTIC speakers. 116Degrees in las vegas today

[Norbert]

I had a look on the Silvaweld Tube Reference OTL amplifier's datasheet (http://www.silvaweld.com/e-7.htm) and it states a damping factor of only 10! I don't think that this is a good match for a woofer like the 2231.
I definitely think that your boomy bass problem is linked to this thread: http://www.audioheritage.org/vbullet...=&threadid=558
Another fact which probably worsen things is the corner placement.

Best regards,

Norbert

[boudu]

maybe you 're right for the amplifier, I have the possiblility to test them with an MC 275 CE, do you think it will be better ?
Regards
Boudu

[IDF]

I have the possiblility to test them with an MC 275 CE, do you think it will be better ?

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Boudu,
McIntosh amps are very well suited for JBL. The Mc 275 Commemorative should work fine. You could also try some solid state versions.
Regards

[IDF]

Boudu
In addition.
Norbert is right, you must absolutely avoid corner placement because it will enhances bass response. Let corners to KHorns ;-)
JBL literature says that the monitor "should be mounted against the wall, and not away from it". For example my 4343s are also nearly touching rear wall by one corner and +/- 10 cm on the other rear corner.
Hope this helps.

[Norbert]

I think the McIntosh MC275 will do the job. Apart from other amplifiers I'm runing a Cayin 788 (KT88 Push-Pull) on my 4430 monitors. The 788's circuit is based on the MC275's circuit especially the output configuration including the trannies. So I think they will behave quite similar. At least it's worth a try.
But do not forget, this sort of amplifier isn't the last word in bass definition and performance on large-size JBL monitors but it's more than acceptable.

Best regards,

Norbert

[MikeM]

The manual that says to place the monitors against the wall is now 30 years old. Amplifiers have progressed enough to have enough grip to controll the loend with out adding the rear wall room gain thing. Sound like maybe you ARE AGGREVATING A ROOM MODE by driving the system to compete with the corner horn. Again try diffrent room placement. With the L300 I found the best position was 4 foot out from the back and side and move your listening chair Farther away.I dont know you decor but try placing a large tapestry on the rear wall to adsorb some of the refection and boom. and good amp with conrtol for the lows will be wise. Mark levinson make some great lowend amps for biamping. And equalization is another bumpy road.
Have fun and good luck. Just relax and maybe that boom want be as bad as you think.

[IDF]

"The manual that says to place the monitors against the wall is now 30 years old. Amplifiers have progressed enough to have enough grip to controll the loend with out adding the rear wall room gain thing".
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I don't agree.
I'm currently running an amplifier whose damping factor is 200. But if I don't have the rear wall load, I don't have the soundstage.