Try the GPA 34647 diapraghm, - check this out - Altec Symbiotic vs GPA Pascalite 'phrams
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I am surprised to find that the highs roll off very early using my "new" 802-8D/511B horns. They are -6dB at 10kHz! They recently returned from GPA, where they remagnetized and checked the diaphragms. They said they had the better aluminum diaphragms with higher freq output despite one of the drivers badged as "Symbiotik". Is this normal?
Steve
Try the GPA 34647 diapraghm, - check this out - Altec Symbiotic vs GPA Pascalite 'phrams
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EDIT: Yes, 802-8D have symbiotik badges but not the phragms unless uncle mel installed them after purchase.
Are you seeing a suckout at 10k with the signal rising again above that, or are they rolling off a cliff at 10K?
802 has a bit of a suck out at 10k. This is at least partly why Altec built some EQ into the more modern networks.
Even the current issue 802 from GPA has a ~10db suck out at 10khz.
Last edited by bowtie427ss; January 23rd, 2017 at 08:49 AM.
Not all vegetables make good leaders.
It is a complete rolloff, no energy at all above 15kHz. How can I tell if I have the Symbiotik diaphragms? They told me they had the correct diaphragms, its very frustrating.
- - - Updated - - -Originally Posted by bowtie427ss
Found this white paper on Symbiotik diaphragm development. The frequency response in the paper looks exactly like my horn response. I think GPA gave me the business or didn't really look at them.
Steve
http://www.nutshellhifi.com/library/...-in_Emilar.pdf
Symbiotik left with the mylar/kapton/plastic surround.
Not all vegetables make good leaders.
They are definitely NOT the Symbiotik diaphragms. All aluminum surrounds. Now I am really perplexed by the lack of anything above 10kHz.
Symbiotik left with the mylar/kapton/plastic surround.
Last edited by samoore; January 23rd, 2017 at 10:38 PM.
Are you running the drivers direct to test them or are they going through a crossover? Possibly a crossover problem?
BillWojo
What are you running them through? Do you have any other speakers you can test to see if its something else in the chain, you might have a filter built into your amp or receiver for example my Fisher tube receiver from the 60s had built in filters and had a triode based pre section that has the "miller effect" this causes the HF to roll off rather early.
I tested the 802-8D against my other full range speakers using the same electronics, my other speakers extended well up to 20kHz in comparison. I am not using the Altec VOTT crossover network, I am using my own active crossover from Marchand Electronics. New theory, perhaps the VOTT crossover has some EQ built in that extends the highs of the 802-8Ds a bit? My active crossover is feeding them flat frequency sweeps with no EQ.
Does anyone know if the passive Altec VOTT crossovers have any EQ built into them? That might explain my issue, which would of course mean the the 802-8D naturally roll off very quickly after 10kHz with no EQ.
Steve
If you are referring to the A7 N501-8a crossover it just has basic HF L-Pad attenuation.
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