amp for L300

[tv506]

Hi,

I am going to buy an AES/Cary model ES1 300B amp for my L300 speaker. This amp only rated at 7 Watts per channel. Will this amp has enough power to drive the L300? I notice that the L300 is an efficency speaker but I don't know how much db? It is 93db or 96db? Where I can find the formula for loundness (ex. db, watt, etc)? Any input will be greatly appreciated.

Thanks,
Taylor

[Oldmics]

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[Mr. Widget]

The L300 is rated at 93 dB with one watt at one meter. This means that clipping your amp at 7 watts (which is not a good idea) will give you about 101 dB at one meter. My guess is that you will be unhappy with the results.

To use an amp of that low power you need a speaker that is able to play as loudly as you like to listen with only about 1 watt. Actually 0.7 watts would be better. It is a good idea to never run a steady output of more than 10% of your total available. Yes even with lush sounding tubes.

If you are fixed on a 300B amp you should consider a maximum efficiency design such as an all horn design, or one with a D130 or similar high efficiency woofer. These are the types of speakers that were popular when a 10 watt amp was the norm. For the most part they do not have the deep bass that the L300 is capable of and in many cases they are not as linear over the rest of the audio spectrum either.

Alternatively the horn section of your L300 is very efficient, about 105 dB per one watt. You could bi-amp them with a 100 to 200 watt solid state amp on the woofer and the 7 watts up top. This could be very successful but will require minor surgery.

[Tom Loizeaux]

I agree with Mr. Widget that 7 "tube" watts MAY be enough for the compression driver but not nearly enough to properly drive the 2231. I push my 4333s (pro version of the L300) with a pro quality 150 wpc solid stae amp. It pushes it fine, but I really should have a little more reserve power to keep the woofer spikes well away from nearing clip.
JBL suggests useing and amp that can deliver DOUBLE the watt capacity of the driver when using the speakers for studio playback or critical monitoring. (300 watts per/ channel in this case!)

Tom

[Norbert]

Probably you will not encounter any problem driving the L300 with an 300B amplifier regarding power and efficiency, but I think that the damping most feedbackless or low-feedback SET amps provide to heavy-weight woofers like the 2231 or 2235 (155 gr.) will not be sufficient.
I noticed that when I tried my variety of amplifiers to drive my 4430. My SET 300B amplifier (Sun-Audio) is really not able to control the 2235 woofer. The result is a boomy bass. I also tried a KT88 (triode) PP amp with low feedback (Cayin 788). This amp already works much better than the SET 300B but a really controlled bass I can only achieve with a SS amp (Hafler 9505).
According to my experience SET amps are great for high- and mid-range. For driving the bass of your L300 I guess you will have to look for another solution.

Best regards,

Norbert

[MikeM]

Originally posted by tv506
Hi,

I am going to buy an AES/Cary model ES1 300B amp for my L300 speaker. This amp only rated at 7 Watts per channel. Will this amp has enough power to drive the L300? I notice that the L300 is an efficency speaker but I don't know how much db? It is 93db or 96db? Where I can find the formula for loundness (ex. db, watt, etc)? Any input will be greatly appreciated.

Thanks,
Taylor

The cary tube amps are generaly high resolution units and 7 watts may be suprisingly acceptable. Of course you will not be able to play loud on high dynamic digital recordings which sometimes require 10db of headroom at least. If you into Lp records this may be very intresting. Of course you will not have extreme lowend extension ect, but im sure you can fiure this out. I ran a audio research classic 30 on the l300 with staggering results.

[Guy L]

Originally posted by MikeM
The cary tube amps are generaly high resolution units and 7 watts may be suprisingly acceptable. Of course you will not be able to play loud on high dynamic digital recordings which sometimes require 10db of headroom at least. If you into Lp records this may be very intresting. Of course you will not have extreme lowend extension ect, but im sure you can fiure this out. I ran a audio research classic 30 on the l300 with staggering results.

And I ran a 14 wpc Eico HF-81 and a 20 wpc Marantz model 2 monoblocks with amazing results as well.
At the moment, I am running an Airtight ATM300 with my Altec "Big Red" but they are more eficient than the L300's.
I think that you'll be able to enjoy the L300's driven by the Carys.

Good Luck

[GordonW]

See my "Another magic JBL speaker/tube amp combo" thread for info on how I hooked a garden-variety Stromberg-Carlson EL84 tube amp to L77s... and wasted half a day just listening to it in awe afterwards...

I think the critical difference is, between amps such as the SC, Airtight, ARC D30 and such, is that those amps actually use a sensible, "modern" feedback system, which gets the output impedence of the amp down to a REASONABLE level, for modern speakers (ie less than one ohm output impedence).

However, with 300B-based amps, there really IS no feedback, and the output impedence can be in the range of several to several TENS of ohms. This basically removes effectively all the electrical damping to the speaker cone!

If you were to do this, you might want to swap out the 2231, for say, a 130A or 2220... or if you could find it, a '145, that'd be the ticket, except for possibly minor cabinet surgery to the woofer hole... they're very low Q, so they would be a better match with that amp on bass than the 2231... and with that amp, the Q will be raised enough that you should still get bass to surprisingly low frequencies. Not like the 2231 LF extension, but real bass...

Not to mention that the efficiency is higher on those (less cone mass), so that it will have better transient output on low power... I'm willing to hedge a bet that this might sound better on the Cary than the 2231 or 2235, for that reason if nothing else.

Regards,
Gordon.

[Ian Mackenzie]

Taylor,

I have tried the SET 300B Cary on my 4345 diy, the 4345 is 95dba and there is enough level for passive non transient music.

But pushed and you tend to get that bloom effect and the resolving power disappears.

May I suggest another excellent Cary amp to try is the SL 70 35+35 push pull, using EL34's or KT88's.

It has 90 % of the SET resolving power, massive power and control. This amp was made for JBL, it really rocks and is very accurate.

You may even find one on the second hand market, good luck.

Ian

[Peter W.]

I am using the S3100 MKII with 95db sensitivity.

I have used the Audio Note Conqueror, a 300B SET amp with one 300B tube at 7w per channel. Very sweet sounding but bass was not good enough.

I then changed to the Audio Note P4, a mono block parallel single end amp with two 300B tubes per channel at 18W. It was much better but damping was still not good enough and bass was boomy. The mids and highs are so good and vocals are so beautiful but I finally had to give them up because I could not live with the poor bass.

I am now using the Master Sound Mono 845, parallel single end mono block amps with two 845 tubes per channel at 40w. Damping is very good and bass is tight. Vocals not as sweet as 300B but they sound more natural and real to me. I have even tried bi-amping with 300B for the horn and 845 for the woofer but they didn't match.

Unless you particularly like the sound characteristics of the 300B tubes, I think you will enjoy more variety of music with higher power amps.

Best regards,
Peter W.

[tv506]

You are all very kind and helpful. Thank you very much for all you help and suggestions. I never owned or heard a 300B amp before so I will give it a try. If it does not work out, I will use this amp for my JBL L100. I will replace as many amp as I need to get it sound right, but not the JBL L300.

Which tube amp sounds best and how many watts are enough for the L300?

Thanks again,
Taylor

[Alex Lancaster]

Why not a McIntosh 75W/ch?, they are not too expensive and would give You enough bass.

Alex.