250Ti Jubilee happy unhappy

[filigran]

Hi filigran

As far as I see it , if you are missing output strength in the HF & UHF areas, the reason(s) must be from one ( or a combinations of ) the following three possibilities .

(1) The custom crossover you are using was made with the incorrect value resistors.

- You can easily determine if this is the case by comparing the value of the present resistors to the values speced for the N250Ti Jubilee.

(2) Your custom crossover may have inductors that have higher than speced DCR values .

- Again, You can easily determine if this is the case by checking the DCR values of the present inductors to the values speced for the Jubilee network.

(3) The usage of Mundorf capacitors has drastically changed the "voicing" of a system that was voiced for "bypassed" , "DC-biased", "electrolytic capacitors".

- This is a possible explanation and not as far fetched as it may appear , though it relies on accepting a phenomenon that's not talked about much ( at least not around here ) . Since I've never heard Mundorf caps / I can't speak with any first hand experience on how they might effect the overall voicing of your 250ti system.

- I have found in my own studies on caps , that as caps get smoother & deeper sounding / there can be a perceived level-drop to the UHF area . I haven't found it to be measurable / but subjectively the effect is very real . I've even taken to bypassing smooth sounding networks with sharper sounding caps - just to restore a sense of "loudness" to the UHF area . Also, I find that smooth/deep sounding network legs ( a compression driver circuit in my case ) must be turned up a bit to restore subjective balance ( when balanced against woofers ) . This increase is usually confined to the neighbourhood of a fraction of a db ( maybe .5 db ).

- The Mundorfs just might be subjecting you to this effect .

- You will need to reduce the resistive padding on these 2 network legs to test out this idea .

- The problem in attempting a change to the padding ? One needs to know the AC impedance curves for the 2 top-end drivers to reasonably alter the values of the padding resistors.
- I don't have those curves to give you / maybe someone else does and can post them.
- Without them, you will most likely change the circuits' working impedance in that area. The preceeding LC components are set to work to a specific impedance. A change in working circuit impedance will result in a shift to the crossover points. Not a good thing .

Ehhh, I know the basics of R, L, Cs in the network for speakers, thank you.
The de-biasing was made in taking one capacitor of the half value and no 9V between them.

Hi Earl K,

first thank you for your infos,

to (1):
Indeed I changed today some resistors. One was definetelly the wrong value (R6 1Ohm instead of 9.1Ohm, as I told before) and the resistors R12, R13 was changed from 2.2 and 6.8Ohms to the original 1.2 and 15Ohms, which gave more power to the UHF Chassis: from -4dB to -0DB. And I changed R7, R8 from 9Ohms to 7.5Ohms to achieve -0DB instead of -2dB in the HF.
All other values are +-0.1Ohm correct.

to(2):
DCR values of the present inductors were taken into account.
After short listening the situation improves a bit: more heights as expected. But my small Nubert speakers (NuBox 380, very linear 2way system) sounds still a bit more fresh and higher.

Pos. signal from the network is connected now to LF-black, MF-red, HF-male, UHF-(+)sign.

to(3):
Well, this is a complex field...hmmm

I think next I will change the Mundorf network to the Original Jub. network to hear what it should sound.

grmpff...

[Guido]

Welcome Filigran!

I watched your Jubilees on Ebay and was sure this would be the case: messed up networks.

See, Mundorf really pisses me off! This company is one of the most arrogant companies ever. They sell stupid nonsense like silver/gold capacitors that cost fortune. I tried them and they do not sound any better than a good PP cap bypassed with PP film foils.
They never answer mails that are in any way critical! Must be a company advice

The fact that they are completely unable to "modify" a JBL network is absolutely logical for me.

Your original networks are also not THAT fine as they are made from electrolytic caps only.

PM me with you email. I'll try to help you.

[filigran]

Welcome Filigran!

I watched your Jubilees on Ebay and was sure this would be the case: messed up networks.

I´m not sure that the network is messed up.

See, Mundorf really pisses me off! This company is one of the most arrogant companies ever. They sell stupid nonsense like silver/gold capacitors that cost fortune. I tried them and they do not sound any better than a good PP cap bypassed with PP film foils.
They never answer mails that are in any way critical! Must be a company advice

The fact that they are completely unable to "modify" a JBL network is absolutely logical for me.

Why so angry? They did the same thing like Giskard when he biased the original N250Ti. All the other values remain the same.

Your original networks are also not THAT fine as they are made from electrolytic caps only.

I will hear it when I have time to change networks (thank god I have the Orig. Jubl network too).

PM me with you email. I'll try to help you.
My mail adress should be in my profil. What would you like to know?

.

[4313B]

They did the same thing like Giskard when he biased the original N250Ti.

Oh pew! They WISH they were as good as me.

[filigran]

They did the same thing like Giskard when he biased the original N250Ti.

Oh pew! They WISH they were as good as me.

Hi Giskard, of course you are the guru...

Have you any guru-ideas what else can be wrong or what I have to check?
Is my polarity right?

Thanks in advance, Mike.

PS: Below is a pic of the complete network in the bottom of the box.

[Guido]

They did the same thing like Giskard when he biased the original N250Ti.

OMG
NO they didn't!

You don't need to PM me. It was just an offer for help

[Earl K]

Hi Mike,

- Now that Giskard has showed up , I'll leave you guys to work through the problems with your network .




PS; - If after getting the padding maximized ( among other things ), you believe the problem may still be cap related ( like for instance, the stock voicing depends on a touch of "splash" from the stock recipe , then take a gander at Humble HomeMade HiFi.

- Over the years, Tony G has been developing some useful opinions on different capacitor models. There might be something within his reviews that suggests a direction for you to take to maximize what you presently have .

[filigran]

They did the same thing like Giskard when he biased the original N250Ti.

OMG
NO they didn't!

You don't need to PM me. It was just an offer for help

Hi Guido, what´s your problem?

What has Giskard done to the N250Ti otherwise than doubling the caps and their values (normal serial equivalent) and connrcting 9V between them?

I hear very loud music but I´ve still fine ears, no need to shout.

[Steelyfan]

Hello Filligran,
I remember from reading the auction description that the cones were treated with some kind of liquid product. "to make them sound even better".
If that is correct, that is another source of tonal change.

The networks for/with Mundorf are designed by a separate company, (I once had it but did not keep their address) maybe it is wise to ask for their address to Mundorf, in order to have first hand explanation why changes were made compared to original design.