From this link N500 it appears you can move the bus bar around to see what you like best. There is not a lot of info, but it might be helpful. I would try it with and without the resistors. Also try various positions of the N7000 Lpad... I assume there is an N7000.Originally Posted by rugy
Widget
Hi
may be can help :
http://www.300b.net.cn/bbs/ShowPost.asp?PostID=14486
http://www.300b.net.cn/bbs/UpFile/Up...8121982557.jpg
http://www.jblpro.com/pages/pub/obsolete/3105-3115A.pdf
regards
ivica
Thank you, thank you, thank you!!
Searching for this info has been frustrating and consuming a lot of time.
The links are extremely helpful. At some point I will rewire the speakers but for now I want to listen to them
in a proper set up with my vinyl as a source instead of my iPhone...........
When I do rewire has anyone mounted the crossover externally from the speaker ??
Just thinking that the 150-4C must excite the cabinet which can't be good for the crossover.
Waiting till the rest of the household wakes up so I can reassemble the speaker. Then move them into
my listening room and listen to some music.
Again thank you for all the help, it is much appreciated.
YES that's. the way the 075 tweeter is mounted,,To one side,,After checking the Hartsfield in St.Louis.. Yours matches construction exactly......ENOY your new found Harstfields.
One more thing,,, The level control at the bottom back..Might have been a later modifacaion... The ones in St.Louis definitely had a N7000 xover.
Congratulations rugy! You've got some lifetime keepers there.
At the JBL History exhibit in Northridge, 2006-2007 (at least) there were two Hartsfields on display, one early, one late. The late one had an 075 visible through the grille cloth.
I first heard the Hartsfields at Hal Cox's home in Mill Valley, CA in 2002 or so. Hal cranked the volume on symphonic material and performed as virtual conductor with arms swinging! The reproduction of orchestral tympani was as good as I have ever heard, before or since.
I fondly remember my phone conversations with the late Margaret Thomas, widow of longtime JBL owner William Thomas, in the early 2000s. She told me that the Hartsfield "put JBL on the map," and that it established JBL's reputation as the "best you could own." Margaret was Thomas's secretary at the time, and she appeared as the model in some of the early Hartsfield literature. Hal Cox told me that the Hartsfield was introduced to compete head to head with the Klipschorn, and was priced a bit higher intentionally to gain prestige.
Update.
Have moved the speakers into my listening room. Boy these demand a lot of real estate in the room which is 14.5 x 9 x 21.3 feet.
Unfortunately I cannot move my main speakers out of my room so I have the Harts directly in from of my main speakers.
Have them separated as much as I can and the results are ok but too close really to my listening chair.
My room is also a "movie room" which is shared with my music so I have a rear elevated platform with a sofa, the viewing gallery.
Anyhow have tried two amplifiers (Classe DR3, Wyetech Topaz ) with them and two make a hum that is just too loud for listening.
These two amps are dead quiet with my main speakers so what gives ?????
Used cheater plugs, moved power cords, moved speaker cables etc to see if this would help but same result.
Being frustrated I brought in a little Naim Nait 5i which is used in the family area and no hum at all......
So my go to amps are too noisy for the 16 ohm Harts but are fabulous on my main speakers.
Does this mean the Harts are like an electric microscope which brings forth any amplifiers misgivings ?
I know that vintage amps of the Hartsfield era may have had 16 ohm taps available on the amps.
Should I be looking for vintage amps/gear ??
Thanks for reading.
Mike
If the Hartsfield speakers are in the 100db efficiency range, the noise from the Wyetech 211 amp is probably a combination of the directly heated filaments, and the fact it's a no feedback design. I've seen that issue many times with 100+db speakers. If your other speakers are below 92db, you probably could hear it if you were close to one of them, but not at the listening position. If they're below 87db, you'd never notice the noise. No idea why the Classe would be making noise, but again, I'd bet you could hear some noise from your other speakers if close to them.Update......
......Anyhow have tried two amplifiers (Classe DR3, Wyetech Topaz ) with them and two make a hum that is just too loud for listening.
These two amps are dead quiet with my main speakers so what gives ?????......
.
Mike
Hi Mike. No, I'd say something has got to be "out of kilter." I'd just go through the usual one-by-one elimination process. But, it sounds like either a failed cap/short/wiring in a crosssover or similar. Is it both sides? Have any alternate crossovers to clip in temporarily? Is it 60 Hz from woofers only? Clues. My rig uses a 3155 crossover (4-way) with the Hartfield horn as the treble driver. It is dead quiet with any of my old or newer amps. It is approx. 95 db spl efficiency (bass reflex) so is sensitive to noise and I use a tube preamp as well. A detective episode. Old gear is always a challenge! I'd check, wiggle, etc. all the basic wiring. Thinking out loud here. Curious to know what you find. Also MikeUpdate.
Have moved the speakers into my listening room. Boy these demand a lot of real estate in the room which is 14.5 x 9 x 21.3 feet.
Unfortunately I cannot move my main speakers out of my room so I have the Harts directly in from of my main speakers.
Have them separated as much as I can and the results are ok but too close really to my listening chair.
My room is also a "movie room" which is shared with my music so I have a rear elevated platform with a sofa, the viewing gallery.
Anyhow have tried two amplifiers (Classe DR3, Wyetech Topaz ) with them and two make a hum that is just too loud for listening.
These two amps are dead quiet with my main speakers so what gives ?????
Used cheater plugs, moved power cords, moved speaker cables etc to see if this would help but same result.
Being frustrated I brought in a little Naim Nait 5i which is used in the family area and no hum at all......
So my go to amps are too noisy for the 16 ohm Harts but are fabulous on my main speakers.
Does this mean the Harts are like an electric microscope which brings forth any amplifiers misgivings ?
I know that vintage amps of the Hartsfield era may have had 16 ohm taps available on the amps.
Should I be looking for vintage amps/gear ??
Thanks for reading.
Mike
Hi Mike,Update.
.......
Anyhow have tried two amplifiers (Classe DR3, Wyetech Topaz ) with them and two make a hum that is just too loud for listening.
These two amps are dead quiet with my main speakers so what gives ?????
Used cheater plugs, moved power cords, moved speaker cables etc to see if this would help but same result.
Being frustrated I brought in a little Naim Nait 5i which is used in the family area and no hum at all......
So my go to amps are too noisy for the 16 ohm Harts but are fabulous on my main speakers.
Does this mean the Harts are like an electric microscope which brings forth any amplifiers misgivings ?
I know that vintage amps of the Hartsfield era may have had 16 ohm taps available on the amps.
Should I be looking for vintage amps/gear ??
Thanks for reading.
Mike
As You know, your Hart-speakers are high efficiency speakers, so You have to use very, very low-noise power amps, to drive them. A fiend of mine has Rotel RB-990BX amp, and on 2242 & 2202 & 2450SL-1.5 ( sensitivity about 98dB/1W/1m) hum and hiss noise can be heard when putting ears near them.
Here I want to emphasis that RB-990BX is rated noise figure of 120dB (A).
In order to reduce the problem, I can see two possibilities:
one to use very high quality "step-dow" transformer or
resistor network that would reduce the voltage on the speakers connection.
regards
Ivica
Hi Ivica. But he says, "Just too loud for listening." ie, very loud - as though there is a major failure / glitch somewhere. Not an irritating background hum. I'd be hesitant to jump to conclusions until the origin of the noise was certain. Detective story. Mike
P.S. I used to run the old 030 stuff (100db?) back in the 60s with all tube gear of the day - Marantz - and was always able to get the system quiet enough that you couldn't hear any noise while listening. Always a bit of hiss at idle, etc. But generally quiet enough.
Two points.
1. As has been pointed out, with high sensitivity speakers any ground issues or other noise issues which may be perfectly acceptable with average sensitivity speakers may become painfully obvious... but there may also be something amiss with the electronics in this case if the noise is more than simply distracting.
2. If the Hartsfields are not fully back into corners of the room your bass extension will be diminished.
Widget
If it's in a home theater system and there is a coax cable connected to
any of the components from outside, try temporarily disconnecting it.
Also could try shorting the inputs to the amp driving the Hartsfields
(preamp disconnected first) and see if the noise persists ... working
your way backward if that stage is acceptable.
Detective Mike reporting.
My listening room is shared with a projector and a screen but only use Blue Ray as a source and use no coax cable in my room.
Have an Audience AR6T for "line conditioning" which I have used with great results. Lifted the ground on this and no difference re the hum.
So on to the amps in my room. Have one more amp to try which I will take out of another system. Report on this later.
Testing was done with amp on and preamp off using the same power cable plugged in the AR6T and speaker cables switched from amp to amp. Ear to the speaker inches away from driver.
Wish that the speaker main terminals were larger and not up so high on the speaker.
1. Tried the Wyetech Topaz through my main speakers and there is a small hum with my ear up against the speakers.
Noticeable but barely from my listening position which is 11' away from speaker. Cannot hear it when playing music on my main speakers but with the Harts its very noticeable. So much so it's too annoying to use with the Harts.
2. Classe DR3 has a minute hum with my main speaker which I cannot hear at all from my listening seat.
But again loud enough that I cannot use it the Harts.
3. The Naim Nait 5i has no noise what so ever with my main speakers.
With the Harts also no noise.
This means that the Harts are like a electron microscope which magnify all good and bad.
The Wyetech with my main speakers ( 93 DB ) are my fav but with the Harts are a no go.
Love the sound of tubes so I will contact Roger from Wyetech for help on the hum/noise issue.
Last night we had a long listening session which lasted till the wee hours.
Moved my dusty CD player close to the Naim so we could listen to some redbook instead of my iPhone and Naim combo. My CD player has not seen any action in over two years due to my listening preference of vinyl.
None the less we were listening to great music in our room coming from the big Harts last night.
This speaker does so many things right that I can hardly wait to get them optimized and up to the Island.
Monday I will bring my last remaining amp into my room and will keep my fingers crossed for no noise/hum.
Picture of my temporary set up. Messy I know but this is an experiment right now.
Thanks for reading.
Well... it at least confirms their sensitivity.
Widget
There are currently 1 users browsing this thread. (0 members and 1 guests)
Posting Permissions
Reply With Quote
