My "First Watt" experiment

[Chris A]

I don't see any way the F3 should give you a boomy sound(since it is only on the K402/TAD) unless there is a level balance issue(ie: too much from the LF) due to the amplifier's different gain/ input sensitivity.

This is what I referred to, Tom. This is a Dx38 settings issue or a connection issue, if true.

I'm thinking that this is a refurbished amplifier problem from the vendor, but it doesn't hurt to check out the other pieces of the puzzle before the amplifier goes back to Reno HiFi.

Chris

[Chris A]

Note: Chris is also typing and thinking faster than I can.

That's the first time I've been accused of that - I guess that's a backhanded compliment--that I'll take at face value [] . Sorry for typing too fast: I'll try to slow down in future posts.

Actually, I was trying to stay ahead of the "repeated and updated Dx38 settings posts" from others by staying with the corrections before they cascaded into a long list of repeated-but-slightly-updated settings (...like they have already, unfortunately...). It would be nice for those authors to point back to the first Dx38 settings posting now that it's been corrected for future use by folks that aren't posting currently, like we've done for the Jub owners thread list that Coytee posted here. That way it will be less confusing for others new to the domain of actively crossed Jub audio nirvana.

Chris

[Don Richard]

Doesn't the F3 use unbalanced inputs, and aren't the Dx38's outputs unbalanced? There is usually a 6dB difference between the two unless the outputs are of the servo balanced type. That would cause lower HF output. Take some measurements to check the acoustic output and frequency balance of the system. A Radio Shack SPL meter and a test CD would show you what you need to know.

[Chris A]

Take some measurements to check the acoustic output and frequency balance of the system. A Radio Shack SPL meter and a test CD would show you what you need to know.

[Y] Seconded.

Doesn't the F3 use unbalanced inputs, and aren't the Dx38's outputs unbalanced? There is usually a 6dB difference between the two unless the outputs are of the servo balanced type. That would cause lower HF output.

I used a Rat-Shack SPL meter to balance the amplifier channels using a test CD both above and below the crossover frequency of 400-450 Hz. That is why I was so verbose about my setup AND my settings, above. I find it easier just to measure with a meter and then set the relative High-Low amplifier channel gains.

Since I'm using an AVP with Audyssey (i.e., with a microphone to do in-room measurements), I use that device to equalize gains and delays for the other 5 speakers in my main rig (center, surrounds, and two horn-loaded subs). Stereo preamps don't do that function, I've found, and the AVP that I use has a very good preamp section when used in "Pure Audio" mode, and a very good internal DAC to eliminate unnecessary analog line-level inputs from disk players, etc. which are uniformly susceptable to noise and other gain level issues.

I use an XLR-RCA cable to connect to the F3 from the Dx38 crossing/EQing/delay-correctiing the Jubs, and I haven't had any problems with power line noise. In fact, the F3-TAD 4002 HF channel is dead quiet when quiescent.

Chris

[Cornman]

Thanks to all for suggestions & help. Here is a email I just received from First Watt -

Hi Joe,

Thanks for keeping me in the loop. I’m sorry the F3 is not performing as expected.

I’m
shocked to hear about your experience. We’ve helped hundreds of people
to own and enjoy the F3, it’s one of our very favorite models, and
while I don’t doubt your personal experience, we’ve never before had a
client who complained of the F3 being boomy—not at all. We have other
models while can easily be boomy, but not the F3. The F3 is also an
Extremely reliable model, so it’s very unlikely that there’s a problem
with the amp, and with both channels having the same problem.

I
thank you for asking, and I’m sorry I don’t have many suggestions to
remedy the issue you’re experiencing. Usually the F3 is plug-and-play.

The
F3 does have a low input impedance. Perhaps the preamp or DAC driving
the F3 doesn’t like the low impedance (and I think we discussed this, so
I didn’t expect a problem; usually tube preamps don’t like the low
impedance). The impedance difference can cause the equalization to be
maladjusted—so it can be corrected with equalization adjustments.

If
you re-tweak as you can and if the F3 doesn’t create magic in your
system, a return and a refund will be no problem and we’re always
friends—no worries.

I’m always here to do anything I can for you.

Truly, Mark

Reno Hi Fi

First Watt

Just to clearfiy for ever one I have used other amps in this system with Dx settings same as now with good results, most recently & still using the Princess 300b mono blocks. Although it did take me a while to adjust to the sound of the Jub's compared to the Cornwalls - at first I was a bit overwhelmed (best description I can think of) the sound is just so much larger, it took me awhile to get in the groove with it. I had my Cornwalls so dialed in for the sound that makes me []- the change was so big & startling I was not sure I would be happy with the Jub's or not. Looking forward to dragging the Cornwalls back into the listening room for a direct comparison with the Jubs some day, I am pretty sure at that point I will say the same as others here have -"there's no going back".

I will put the F3 back on line again today, experment some more & give it a second chance. But I suspect there is some other component in my system that is just not compatible with the F3. Thinking back on it last night I did tun down the Dx output levels of line 1& 3 (bass), but did not try turning down the output levels on the Crown. Even my wife committed last night how bad the music was with the F3, & she usually does not notice much difference with various gear that I experiment with. Aside from the booomie bass the mids & high fq. were just down right strident & unclear. Anyway having fun. [Y]

Cornman

[mikebse2a3]

Cornman

On the K2 which position is your input switch set at 1.4v or 26db?

Are you using a balanced interconnect between the EV and the K2? If you are using unbalanced interconnects then the same possible (-6db) loss (that Don mentions in his post) will be the same for the K2 and F3 from the EV DX38 but if your Balanced from the EV to the K2 and unbalanced to the F3 then you "might" need to take the possible (-6db loss) into account.

Note: I'm assuming all the EV DX38 output level controls are in the same position for the following recomendation.

From the sensitivity information I've seen on the K2 and the F3 I calculate that if you are using the (1.4v switch setting) then reduce the K2 level control by (-20db) or if using the (26db switch position) then reduce the level control by (-13db). Note: if you have to allow for the F3 unbalanced connection mentioned above then the (1.4v switch setting) K2 level control will be (-26db) or the (26db switch position) K2 level control will be (-19db).

I hope all this makes sense..and at the very least it's worth trying to see if it gets you close to a balanced sound [] It should be very audible which reduction is correct on vocals.

mike tn

Woops edited: taking into acount the "possible need" for the F3 unbalanced connection then the K2 level control should have been what I have written in Red now.

[Cornman]

All very good points Mike. I had completely forgotten about the setting on the back of the Crown. I am going to ck that right now.

The connections from DX too Crown or balanced, but to the F3 are unbalanced using adapter to RCA end, this has not caused any problems so far with other gear.

I am putting the F3 back on line now, will see how it goes.

Cornman

[mikebse2a3]

The F3 does have a low input impedance. Perhaps the preamp or DAC driving the F3 doesn’t like the low impedance (and I think we discussed this, so I didn’t expect a problem; usually tube preamps don’t like the low impedance). The impedance difference can cause the equalization to be maladjusted—so it can be corrected with equalization adjustments.

Just to note: The EV DX38 is driving the input of the F3 and shouldn't have any problem with it's input impedence so the Pre-amp interaction can't be at fault in this case.

I'm impressed with the dealers attitude in his response and seems to be a class act![Y]

[mikebse2a3]

The connections from DX too Crown or balanced, but to the F3 are unbalanced using adapter to RCA end, this has not caused any problems so far with other gear.

Same here as far using unbalanced interconnects has never been a problem. You do have to watch for the possible (-6d loss) and take that into account sometimes.

What happens sometimes is even though a piece of equipment might have an XLR balanced input connector doesn't mean that the input circuit itself is actually balanced so sometimes you just have to experiment to see which works.

miketn

[Cornman]

Mike said -" I'm impressed with the dealers attitude in his response and seems to be a class act! "

Absolutely a great dealer response, [Y][Y] thats one of the reasons I decided to go ahead with this experment -there ten day return policy. Cant beat that.

Mike I just cked the sensetivity setting on the back of the crown & its set on the 1.4 volt setting, thanks for remindding me.

Have the F3 warming up now,,,,,[8]

Cornman

[PrestonTom]

I agree the dealer is being gracious. However, I don't think he understands (or he forgot) that this set up is bi-amped with two different amps. If he did, then he would have asked about the adjusting the gains since the two amps probably have different gains and sensitivities.

I am still unlcear why the F3 is being blamed for a "boomy bass" when it is handling the tweeter. I am also still in the dark as to whether the set up ever sounded "right" before the F3 was substituted.

I'll quit at this point, since others are giving reasonable advice.

[mikebse2a3]

Hey cornman please note: I have made a correction to my previous post about the db reduction for the K2 that might be needed.

These numbers can sure twist a person up[]

miketn

[mikebse2a3]

I am still unlcear why the F3 is being blamed for a "boomy bass" when it is handling the tweeter. I am also still in the dark as to whether the set up ever sounded "right" before the F3 was substituted.

Tom

I'm thinking that if the HF level is to low then it might be the cause for the bass to be perceived as boomy.

I did have the thought cross my mind that the 300b amp and the F3 level settings should be within a few db of each other.

Anyway it will be interesting to hear what cornman experiences after making some adjustments.

miketn

[Cornman]

Last night was one of those wonderful learning experiences for me. Ounce it becomes clear that answer was right in front of me all the time, & you say to yourself "What a Duffus" I was to not utilize all the control options that are available with an Active crossover system. Over the past decade or so I have been of the philosophy that less is better ( as in less components in the signal steam the better). So I have been slow to adapt to an Active cxo.

Since setting up the jubs, I have never been completely satisfied with the sound. Same issue with all amps I tried - to much imbalance between the low fq & horn. I have been utilizing the DX analog controls to moderate the bass & for the most part had ignored the output controls on the Crown [:$]. Mikebe2a3 said it so intuitively in this thread-

Since I now know you are using the K2 (which has it's own level
controls and input sensitivity switch) for the LF then you can use them
to get you close to a proper balance with the F3 amplifier instead of
the EV DX38's analog level controls if you want to.

I don't see
any way the F3 should give you a boomy sound(since it is only on the
K402/TAD) unless there is a level balance issue(ie: to much from the LF)
due to the amplifier's different gain/ input sensitivity.

mike tn

I dont understand the whys of the diiference in sound from reducing a line at the croosover as opposed to reducing it at the bass amp, but my friends I tell you ther is a very audible difference. I was able to enjoy the First Watt F3 & can understand why some folks like it. Likewise, after listening to the F3 for 90 minutes or so, I put the 300b back on line and the satisfaction level was a huge improvement with the fine tuning that can be had from the bass output. I now run the Dx controls full throttle, & have the Crown output turned down about 10 to 12 db.Huge difference in satisfaction level . [<)] I feel like for the first time I am fully beginning to hear & appreciate the full potential of the K402 Masterpiece.!!!

I would like to hear the F3 in an un biamped setting, may pull the Cornwalls in for a listen just for fun. But so far it was reconfirmed last night tubes still hold the key to my musical heart. []

Cornman

[mikebse2a3]

Hey glad you had some fun and things are sounding better.[Y][]

I'm curious, around what -db reduction did you decide on with the K2 when using the F3 on the K402/TAD?

Cornman if you want to play and learn a little bit, try for example using the F3 on the (Jub LF and K402/TAD of one channel) versus the 300B amp on the (other channels Jub LF and K402/TAD). Also by using the same amp for both the Jub LF and K402/TAD will let you experience what a properly balanced Jub/K402/TAD can sound like and thus will give you a reference point.

Note: Make sure you use a mono recording or at least the same signal as a reference when doing any amp vs amp comparisons this way.

miketn

[PrestonTom]

Hey glad you had some fun and things are sounding better.

I'm curious, around what -db reduction did you decide on with the K2 when using the F3 on the K402/TAD?

Cornman if you want to play and learn a little bit, try for example using the F3 on the (Jub LF and K402/TAD of one channel) versus the 300B amp on the (other channels Jub LF and K402/TAD). Also by using the same amp for both the Jub LF and K402/TAD will let you experience what a properly balanced Jub/K402/TAD can sound like and thus will give you a reference point.

Note: Make sure you use a mono recording or at least the same signal as a reference when doing any amp vs amp comparisons this way.

miketn

Good idea and I would also be interested in the outcome.

[The Dude]

I have been reading as I was hoping for a happy ending. Glad you figured out the issue, and glad to hear it sounds good.

[Cornman]

"Learn a bit" - I want the PHD course []

The reduction was running 12 to 14 db.on the F3.

Most excellent suggestions Mike, cant wait to test them out & get another reference point running in mono - single amp.

Cornman

[jacksonbart]

If it sucks, well then it might or might not continue to suck. Learned that from my first wife.

[mikebse2a3]

Hey cornman

Since you have the K2 (with the -db marked level controls) for the Jub LF there is a realitively easy way to learn how to determine how to set the levels for any amplifier combination you will most likely run your system with.

(1) You will need a test signal such as a sinewave at approx. 500Hz or if that's not possible then as a second best option if you have any test CDs with a 1/3rd octave bandwidth pink noise centered on 500Hz. Run this signal in mono to both channels of the Jub LFs.

(2) A Meter set on AC volts.

While running the test the sound level only needs to be loud enough for you to get a steady meter reading on the amplifier's output terminals or the Jub LF's terminals whichever is most convient. I suggest muting the K402/TAD as a safety precaution and of course anytime your connecting and disconnecting equipment double check that they are making good interconnect connections and are run to the correct LF or HF section before powering up any of the amplifiers.

So with the (K2 on one Jub LF channel) and the (F3, or 300B, etc... on the other channels Jub LF) play the mono test signal and measure the voltage on the Jub LF with the (F3, or 300B, etc...) and use this as your reference voltage to set the K2 driven Jub LF's level control until it measures the same or as close as the level control will allow you to set it.

Note: This will give you a proper level match from the amplifiers and a reference point but I will add that after finding this match if you find yourself wanting to shift the level +/-1db or so feel free because there could be driver variations that are not being accounted for with this method. It is very important to at least know your reference point to tweek from if for no other reason. My experience trying to nail down the proper balance of the Jub LF and K402 HF by ear is it is very difficult when using music because recordings have alot of variation in this region and what sounds good on one recording can sound off on another recording so having a reference point helps alot.

miketn