Woody,
I think that's one of the advantages of Martin's work, that it's laid out well enough that various main drivers can be used depending on budget, taste or whatever. Once relieved of bass duties, a lot of otherwise fine drivers can be used to great effect. In fact, there are some relatively cheap drivers that actually sound pretty good that aren't used much because of the lack of bass.
Best Regards,
TerryO
When peaks hit 90-95 dB (the loudest bits when listening at an average 75 dB,) they still sound good to me. But that's me. You may hear something entirely different. Any louder than that and its just painful for me, so I can't say what is good or bad beyond that. My suspicion is that if you want to reach peak levels of 100 dB or more, you need something other than the FF85k. But I could be wrong. It's sort of like when someone asked me how fast my little Toyota Echo can go; I really have no idea; all I know is that it will go faster than I want to go.
Cheers, Jim
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Got my Founteks today along with the crossover components. I'm a little worried
because their sensitivity of 84.5 is significantly below what's called for in the original design. I'm also probably going to try adding a tweeter or notch filter just to see what happens. Anyone else tried a tweeter or filter with this design?
BTW, I've ordered a pair of ff85k as well so I'll be able to compare them to the fountek drivers.
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These are the Silver Iris woofers I'll be using. Hope they work!
Current experiements with a pair of FF85 (2 facing forward in a uFonken^2) bode well for using multiples of these drivers.
Goinf active would also likely give a bit more dynamic headroom.
Last night these were pulling off Bob Marley without making you think you were missing too much on the bottom.
dave
One thing for sure... the 3" mid-tweeters will very likely improve on the mid-top & overall coherency of the SI.
dave
Thinking about using different drivers is fine. But please recognize, that if you stray far enough from the original concept it becomes your design and it probably would benefit from re running the simulations to dial in the SPL response. You need to check and maybe adjust the relative levels of the drivers and the crossover frequencies and slopes. In some cases a change in the baffle size and shape might be warrented. You might be able to come up with a better design, but if you just swap drivers without doing the work you may get lucky or you may be disappointed.
Hey Martin. I'm interested in doing an OB utilizing a couple of Fostex FE167e (that are already well broken in 
) in a project like this. I would use a Bottlehead 2-watt amp to drive them directly full range (no crossover), but also have on tap a Behringer DCX2496 and a couple of Aragon 125 and 200 wpc SS amps to chose from, to drive the low end. In an earlier post you linked this :
http://www.quarter-wave.com/Back_Door/OB_3_Drivers_Corner_Passive_8_23_09.pdf
Since I would be going active, would the two bass drivers per speaker still be necessary, or would one per side suffice?
) in a project like this. I would use a Bottlehead 2-watt amp to drive them directly full range (no crossover), but also have on tap a Behringer DCX2496 and a couple of Aragon 125 and 200 wpc SS amps to chose from, to drive the low end. In an earlier post you linked this :http://www.quarter-wave.com/Back_Door/OB_3_Drivers_Corner_Passive_8_23_09.pdf
Since I would be going active, would the two bass drivers per speaker still be necessary, or would one per side suffice?
I'm interested in doing an OB utilizing a couple of Fostex FE167e (that are already well broken in
http://www.quarter-wave.com/Back_Door/OB_3_Drivers_Corner_Passive_8_23_09.pdf
Since I would be going active, would the two bass drivers per speaker still be necessary, or would one per side suffice?
You could probably get away with one woofer, but you would be pushing it harder. I would probably also add a high pass crossover on the FE-167E to eliminate the low frequencies and just let it do what it does best. The success of the design is in the engineering details, simulating it first will reduce the number of surprises and get you to the best solution quickly.
You are correct, at this time the U and H frame worksheets do not allow a two way active or passive crossover capability to a full range or midrange driver. I can do it by exporting and combining SPL responses from two different worksheets. This capability is high on the list of improvements I would like to make to the existing worksheets, but I don't know when this will happen.
My experience has been up and down with ss and tubes. I first used a Adcom GFA 535 II with my FE87e version of this speaker. The combo worked great right from the start.
I knew Martin had designed these with a high dampening factor ss amp but wanted to give tubes a try. I purchased a Heathkit AA-151 with EL84 and changed it to work as an amp only. With the original schematic of the amp it wasn't on par with the Adcom but could hear the potential. I did quite a few mods to the amp but the most dramtic change came for beefing up the ps. The modded version was like a match made in heaven, the bass coming from Ray Brown was simply stunning. except over time I found the amp would clip when cranked. Point being tubes can work if the amp is tweaked to work with your system synergy.
Rarely do I listen at volumes that pushed the amp into clipping but it did bother me. I decided to keep an eye out for a Harmon Kardon Citation II and got lucky and found one for 475 shipped
. I then purchased and performed all of the Mcshane Level two plus mods. MY expetations were high with the larger power output and frequency range that those OP's are known for. Once competed and installed I had a similiar experiience where the bottom end was not lost but wasn't where it was.This is where I stand now. I have quite a few thing I would like to do the Citation to hopefully get it to fill in the bottom end. One thing good is the top end blows away what I previously had. I am in the process of building the Jordan Goldwood H frame so the citation mods will wait till those are done.
Brad
Today I was searching around for things to do to try and get more bass out of the Citation II and found this quote in another forum.
"8 Ohm speaker on a 4 Ohm tap, YOU BET. This arrangement exchanges some power O/P for a better damping factor. A speaker with adequate efficiency, which also exhibits dips in the impedance curve, should (IMO) be connected this way, when combined with tubed power amplification."
Hooked the OB's up to the 4 ohm tap and the whole frequency range opened up with a dramtic change for the better on the bottom end. I now have the Citation II on the bench doing other mods that should help out.
Martin if that EL84 amp has 4 ohm taps it may be worth a try.
Brad
"8 Ohm speaker on a 4 Ohm tap, YOU BET. This arrangement exchanges some power O/P for a better damping factor. A speaker with adequate efficiency, which also exhibits dips in the impedance curve, should (IMO) be connected this way, when combined with tubed power amplification."
Hooked the OB's up to the 4 ohm tap and the whole frequency range opened up with a dramtic change for the better on the bottom end
. I now have the Citation II on the bench doing other mods that should help out.Martin if that EL84 amp has 4 ohm taps it may be worth a try.
Brad
"8 Ohm speaker on a 4 Ohm tap, Hooked the OB's up to the 4 ohm tap and the whole frequency range opened up with a dramtic change for the better on the bottom end
Martin if that EL84 amp has 4 ohm taps it may be worth a try.
Brad
It's not "dangerous" for your fullrange speaker to drive it with the 4 ohm tape if it's rated at 8 ohm ?
I loaded two new worksheets earlier today. They can be used to model a two way H frame/OB speaker system with either an active or a passive crossover. This brings the H Frame worksheets up to the same level as the OB worksheets. You can model a double Alpha 15A H frame by calculating an equivalent driver, per my two drivers in a single enclosure document, and using a suitably sized H frame. I think this is a big step forward and will allow users to accurately design a two way system similar to my Jordan OB/Goldwood H Frame speakers.
I plan to revise the U Frame worksheet to a similar level in the next few weeks, as time permits.
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