Apogee Midrange ribbon help - diyAudio
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Old 24th March 2013, 05:41 PM   #1
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Default Apogee Midrange ribbon help

Hi, I am a new member as of today. I have a pair of 1992 Apogee Divas. Like others on this site have posted, you can no longer get to the old Apogee posts to find very useful info. I have read many posts on dyiAudio and can see there are a lot of people very knowledgeable on Apogee subjects. I hope someone can help me with a question. I have had to replace my midrange ribbons at least 9 different times in the last 20 years, as a pair, because I like to play music loud. When Apogee sold the replacement ribbons they were only $60.00 a pair. Now they are about $320.00 a pair. I bought a lot of spare replacement ribbons from Apogee, Graz, and Robert Darangus but I didnít keep them separated. Whenever I replaced my ribbons in the past they ALWAYS measured about 3.0 ohms each. As the Apogee Acousticís replacement literature states they should measure. I just replaced both midrange ribbons this weekend and they only measure 1.67 and 1.78 ohms. I checked and double checked and I installed them correctly. No shorts. My question is; will the lower resistance degrade the sound of these wonderful sounding speakers. Will they "burn out quicker" I now believe/imagine the midrange is now louder and not as full soundings, like it is playing at a higher frequency. I do not see any more movement than normal from ribbons when playing music. I am using an active crossover at 500 hz 6 db, as I have been, so I know the lower resistance isnít affecting the crossover point like it might in a passive crossover. Any help will be greatly appreciated.

If anyone needs pictures of Divas apart let me know.

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Old 24th March 2013, 07:21 PM   #2
a.wayne is offline a.wayne  United States
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You should ask your amp how it feels about the lower impedance and it will change the balance for sure ....

Regards ...
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Old 24th March 2013, 07:29 PM   #3
MiiB is offline MiiB  Denmark
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When you run active, you have the option off reducing the volume, half the impedance, is roughly twice the output, so if you reduce than volume accordingly, your amp shouldn't suffer, and you will restore the old tonal balance.
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Old 24th March 2013, 07:46 PM   #4
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Wouldn't it be an idea to use a steeper filter order so that burn out doesn't happen that often?
An FFT of my life would show a couple of peaks and some low level harmonics, but mainly random noise.
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Old 24th March 2013, 08:16 PM   #5
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I wasn't sure if reduced resistance would increase volume output. I can reduce volume to midrange with active crossover and I will do that. I do not use steeper slope because the 6 db crossover musically bends so well with woofer ribbon.

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Old 25th March 2013, 02:11 AM   #6
john65b is offline john65b  United States
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You 6db slope is likely allowing some low frequency (my guess is under 100hz) out the mid ribbon...which is not very healthy and probably why your burning them out so often...
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Old 25th March 2013, 02:22 AM   #7
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What midrange ribbons you running now? KLM series ? the resistance should be 3ohm on them. I have the latest KLM in my Diva's, also have the passives and the Dax as well
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Old 25th March 2013, 03:35 AM   #8
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These are very early Graz ribbons and they are 1.8 ohms. Graz and I talked several times and I sent him samples of my midrange ribbons when he first started up. I have 4 pair of Graz ribbons and they all average 1.8 ohms. I have 2 pair from Apogee and they are 3.1 ohms. I should have measured before I installed them. But I wouldn't think the sound would be bad on the 1.8, I just need to turn down volume on mids. I have the Dax 1 with modified passives and a pair of non modified passives as well. I would be afraid to use the non modified passive now with only 1.8 ohms.
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Old 25th March 2013, 10:23 AM   #9
DAMIC is offline DAMIC  Seychelles
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Originally Posted by tjc123057 View Post
..... I have had to replace my midrange ribbons at least 9 different times in the last 20 years, as a pair, because I like to play music loud. .........
You have realy a lot of broken ribbons, average one per 2 years. Mine, on Stages lasted nearly 15 years. I think, you should increase the slope, btw I am using 24L/R slope at 500Hz and 84Hz on my tri-amped system (Stages + subs).

Secondly, do you have big capacitor for protection on MRT?
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Old 28th March 2013, 01:14 PM   #10
WrineX is offline WrineX  Netherlands
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noone bothering the fact that 1.8 ohm means complete other crossover as well???

its like almost crossed one octave higher then before with the 3 ohm.. so yeah ur previous would sound warmer because its crossed lower.. now ur ribbon wil last longer but your amplifier may not.

for instance ur 3 ohm is crossed at 1000 Hz, with 1.8 ohm ribbon with the same passive crossover it will be around 1700Hz

if ur fully active my message is ofc not true then just reduce the output by 5 or 6 db and it will sound as it should. (not taking in to acount the ribbons are diferent so it may sound diferent even if the impedance is the same)

Last edited by WrineX; 28th March 2013 at 01:21 PM.
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