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David Ketley
10-07-2010, 08:55 AM
Does anyone know the Urei JBL 813B crossover frequencies, just trying an active set up to see how it sounds?
Thanks
Dave

eso
10-10-2010, 11:21 PM
Probably somewhere in the 1200Hz region, although I couldn't say for sure. They original and A series were based on the Altec 604-8G (I think, or thereabouts) and those usually crossed at ~1200Hz.

Bi-amping would bring the original time mis-alignment back and all of the nasties that go with that, unless you're looking at using digital time correction too. Just my 2Ę, but if you're going to add anything digital to the chain you're comprimising the quality so far that you may as well save a headache and just get some cheap mini-monitors.


eso

David Ketley
10-11-2010, 01:29 AM
I have stuck to the so called original sound of the 813Bs for many years putting different amplifiers cables etc on them one of the most profound improvements was the addition of a sub, the mid range and lows are just wonderful. Problem was I could NEVER get the top response sorted out. So I sent away the crossovers to be recapped but was informed they were not really worth doing as a new of the shelf unit would suffice. Not happy with this outcome I decided to tri amp them. Rather than go and purchase an expensive unit I got a DBX 234 just to see if I could get ANY improvement. At long last I have the full range of frequencies and even without time align it sounds very nice. Any advice on active crossovers with time align would be welcome.
I find it a mystery why it is so frowned on to experiment with these speakers what one is trying to do is to get as clean a signal path to the speakers as possible and there are certainly benefits of active over passive
Nothing digital is added to the chain after the DAC its all analogue.
Dave

richluvsound
10-11-2010, 03:26 AM
http://www.deqx.com/products.php

http://www.audiogon.com/cgi-bin/cls.pl?preatran&1291296130&/Deqx-Hdp-Express-pre-amp-corre


This the starter model , will do everything you need to do and more .....

You need to run this with a PC .... I used my Mac running Vista .... Hours of frustration then hours of fun ... it really will do everthing but , wind your watch for you ;)



Rich

David Ketley
10-11-2010, 10:07 AM
Thanks Rich I did look at that unit but Iíve ended up with a YAMAHA D1030 D-1030 coming from USA, been told it will do the job and the price is right! I still have not got hold of my full amplifier compliment Iím running the mid on my Yamaha PC2062Ms 800W each into 8ohms but not up to spec. I will running with Musical Fidelity amps throughout. Iím amazed at the response to experimenting with these speakers the crossovers on the 813B go through fuses, tungsten filaments and potentiometers and the wire inside was rubbish! The bottom end frequency response in an open room was also lacking as they were designed to be wall mounted giving around a 6db lift in response. The sub has transformed the bottom end but the idea that you can just chuck it into a corner of the room is wrong the response of the helper woofer dovetails in superbly in a position in the middle of the speakers. A lot to do with the bass reflex loading I think.
Dave

richluvsound
10-11-2010, 10:18 AM
Dave,

No worries . I don't think there is ever been a studio monitor that was plug an play :D They are worse than kids for attention ..

Hugemac and I will be up your way next week some time . I have a meeting at speaker builders in Derby . Do you fancy coming with us to hear this Vox ?... maybe grab a bit of lunch or an early supper ?
I wouldn't mind hearing your Urie's either !

how about some pic's old bean ?


Rich

David Ketley
10-11-2010, 10:39 AM
Speaker builders in Derby thats not far from here, Can you give some more details sounds interesting? Not shure the 813Bs will be sorted by then but I would welcome your opinion.
We are at SK23 7RF.
Regards
Dave

richluvsound
10-11-2010, 11:06 AM
Kevin Scotts place ..... http://www.definitiveaudio.co.uk/
:D

Progneta
11-03-2010, 08:03 PM
Does anyone know the Urei JBL 813B crossover frequencies, just trying an active set up to see how it sounds?
Thanks
Dave


the altec urei coax 15 inch used a 1500hz crossover. They used a large black crossover that then connected to a front plate on the speaker cabinet that house fusing and attenuation. Alot of dudes like to use the mastering labs XO for these. I prefer the original crossover that was made for it.