Open Baffle Epiphany!

[kevintomb]

When open baffle/dipole/bipole speakers are placed far enough away from the front wall the distance delayed reflection contributes to depth of the soundstage.

Yes, the rear wave contributes to a larger sound, by "Using" its location within the room, and the resultant rear wave reflection to create a larger, wider or deeper soundstage.

I used to experiment with this effect, by having a temporary acoustical absorbative panel that I could move.
It was amazing how the soundstage could be "enhanced" or altered depending on the placement either behind or off to the sidewall somewhat.
I spent many days (literally) playing with placement, but finally decided on a rear placement, but slightly offset towards the center.

 

[Poultrygeist]

What are you powering the F-15’s with? I’ve read several times in the last year or so, that they like a little more power, even though they are very efficient. Exactly how much, optimally, I don’t know.

Yep, Decwares biggest baffles are HUGE! I’ve always wondered how much that blocks the rear wave. I guess if the room is big enough to allow them to be pulled well out into the room, it wouldn’t be as much a factor.

When I had my baffles built, I just tried to scale them to fit my room. I made them as big as I thought my room would allow.

In the house I've been using 2a3 Bottlehead mono blocks with the F-15's and a plate amp for the H-frame subs.

In the garage I'm using this SMSL DA-9 amp also with a plate amp.

 

[Poultrygeist]

No picture of the new configuration yet but I've replaced the middle row of Alpha woofers with F-15's. I'm experimenting running the 8" Zenith alnico's in parallel with the F-15's powered by the DA-9 while the Alphas are powered by a plate amp. The Zenith's sensitivity seems to be a close match to the F-15's.

 

[Poultrygeist]

Just took these pictures of the Zenith alnico's, F-15's and Eminence Alpha woofers on flat baffles.

 

[Poultrygeist]

 

[essNeff]

Nice work PG!

 

[Genov]

View attachment 2591695

Very nice!!! What is your opinion of the sound so far? Should be outstanding!

 

[Poultrygeist]

Very nice!!! What is your opinion of the sound so far? Should be outstanding!

I did this to prove to myself that two different full range drivers wired in parallel would compete with each other and that no way would this be a good option. I was wrong and I'm still in shock at what I'm hearing.

 

[Genov]

I did this to prove to myself that two different full range drivers wired in parallel would compete with each other and that no way would this be a good option. I was wrong and I'm still in shock at what I'm hearing.

Damn! You're statement is sure to cost me more money

So you are using the 2a3 Bottlehead mono blocks to power the full rangers in parallel?

 

[Poultrygeist]

Damn! You're statement is sure to cost me more money

So you are using the 2a3 Bottlehead mono blocks to power the full rangers in parallel?

I haven't tried the Bottlehead amps with the 3 driver garage system yet, only the SMSL DA-9. The DA-9 has its own sub out, EQ settings and more power.

 

[Genov]

I haven't tried the Bottlehead amps with the 3 driver garage system yet, only the SMSL DA-9. The DA-9 has its own sub out, EQ settings and more power.

So with this setup, you don’t need a separate sub amp? Both full rangers and the bass driver are driven by the DA-9? Sorry for all the questions - I’m not very tech minded.

 

[opnly bafld]

So with this setup, you don’t need a separate sub amp? Both full rangers and the bass driver are driven by the DA-9? Sorry for all the questions - I’m not very tech minded.

Looking at the picture of the back of the baffle, 2 sets of wires are going to it, one to the lowest driver (from plate amp) and one going to the two upper drivers (from DA-9).

 

[Poultrygeist]

So with this setup, you don’t need a separate sub amp? Both full rangers and the bass driver are driven by the DA-9? Sorry for all the questions - I’m not very tech minded.

The DA-9 amp drives the F-15 as well as the Zenith alnico wired in parallel. Parallel here means the speaker wires from the DA-9 are shared by both pair of these speakers. The bass woofers are driven by a 100 watt plate amp which receives its signal from the sub output on the DA-9. A plate amp is the same type amp that is built into a subwoofer. I chose to build an enclosure which allows using it with a variety of subs and woofers. Plate amps are mono so in order to power two woofers it's also wired in parallel ( speaker wires are doubled up ) which also maximizes its power. Two 8 ohm woofers powered by a single mono plate amp changes the load to 4 ohms.

A true sub could easily be added with RCA line outs from the plate amp or by splitting the DA-9's sub output but most of the music I listen to rarely goes below 40Hz and the 15" Alphas cover that fairly well.

 

[Genov]

The DA-9 amp drives the F-15 as well as the Zenith alnico wired in parallel. Parallel here means the speaker wires from the DA-9 are shared by both pair of these speakers. The bass woofers are driven by a 100 watt plate amp which receives its signal from the sub output on the DA-9. A plate amp is the same type amp that is built into a subwoofer. I chose to build an enclosure which allows using it with a variety of subs and woofers. Plate amps are mono so in order to power two woofers it's also wired in parallel ( speaker wires are doubled up ) which also maximizes its power. Two 8 ohm woofers powered by a single mono plate amp changes the load to 4 ohms.

A true sub could easily be added with RCA line outs from the plate amp or by splitting the DA-9's sub output but most of the music I listen to rarely goes below 40Hz and the 15" Alphas cover that fairly well.

View attachment 2592387

Thank you for the detailed explanation! I was confused about how the sub out on your DA-9 figured into it.

 

[Poultrygeist]

Geno, I enjoy your youtube videos and you've got some excellent gear. If you decided to add the F-15 to the mix I believe it may fit the W-15 baffle. Then the W-15's could reside out of the way in their own tombstone baffle as Randy calls them. I bet you've already been thinking about this. BTW your Decware SE84UFO is said to love a 4 ohm load which is what it would have powering the Fast 8 (or 10 ) and F-15 in parallel.

 

[Poultrygeist]

The Dayton SA100 which has a built in adjustable crossover is a good choice to drive a pair of OB woofers ( like the Lii Audio W-15 or the Eminence Alpha 15 ). It's what Steve recommends on the Decware forum and unlike most plate amps it comes in its own enclosure.

 

[Genov]

Geno, I enjoy your youtube videos and you've got some excellent gear. If you decided to add the F-15 to the mix I believe it may fit the W-15 baffle. Then the W-15's could reside out of the way in their own tombstone baffle as Randy calls them. I bet you've already been thinking about this. BTW your Decware SE84UFO is said to love a 4 ohm load which is what it would have powering the Fast 8 (or 10 ) and F-15 in parallel.

Thanks Poultry! I may very well end up trying this out. Like you, I was intrigued and puzzled about running two full rangers in parallel.

How much better would you say this setup is than what you previously had?

I have a second SE84 on order (unfortunately a year out), with plans to run a fully-balanced monobloc setup. So I'll have a bit more power to work with too.

Also, I used that very Dayton plate amp a few years ago, but now use a Crown XLS-1002, that I like better.

Best,

Geno

 

[Poultrygeist]

Thanks Poultry! I may very well end up trying this out. Like you, I was intrigued and puzzled about running two full rangers in parallel.

How much better would you say this setup is than what you previously had?

I have a second SE84 on order (unfortunately a year out), with plans to run a fully-balanced monobloc setup. So I'll have a bit more power to work with too.

Also, I used that very Dayton plate amp a few years ago, but now use a Crown XLS-1002, that I like better.

Best,

Geno

I think the Crown is way better but it now costs over $400. One of my 65 year old Zeniths now distorts at higher levels but even at that they add so much more to the upper frequencies - a much fuller sound and a wider stage than what I was hearing before. I may pull the DX3's from the monkey coffins and give them a try.

 

[Poultrygeist]

 

[opnly bafld]

BTW your Decware SE84UFO is said to love a 4 ohm load which is what it would have powering the Fast 8 (or 10 ) and F-15 in parallel.

FWIW the UFO models have 2 output taps for high and low speaker impedance, therefore it doesn't matter as much what the load impedance is.
The older models were designed to operate "better" with 6 ohm and lower loads, there was an optional X model with OPTs that worked "better" with 8 to 16 ohm loads.

From the UFO owner's manual regarding speaker connections:
"This amplifier can operate speakers as low as 2 ohms, and as high as 16 ohms and everything in-between. No harm can come to the amplifier if the speaker jacks are shorted together.
There is a HI / LO switch next to each pair of speaker jacks on the amplifier. This is used to match the amplifier to a given loudspeaker load. It is operated while music is playing and selected by ear for the best sound. The amplifier will work fine with the HI / LO switch in either position regardless of speaker load, however each setting will make your speaker sound different or perform differently. Choose the setting that you like the best and revisit the setting often to make sure you didn’t just choose one position over the other because it sounded better with the particular recording you were listening to when you made the choice."

No different that most other tube amps.