Quad 2805s. Getting the best out of them.

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I have been asking about these new (to me) speakers on another thread I started, as I had a problem. https://www.diyaudio.com/forums/planars-and-exotics/345692-quad-2805-dust-cover.html That now appears to be fixed, so I am starting this one for general improvement advice. There have been several helpful tips, the latest from Demian (1audio), but I know there is more.
My room is smallish (5.3m x 4.3m), and I can't get far from the front wall, nor lift them up much. But I can make stuff; at the moment I have nearly finished a set of Seismic-type bars for them, which worked well under transmission lines, but who knows if they will work here. But I had almost everything so why not try it?
Subwoofers (Ripole probably), super tweeters, different power amp (valve?), cables (Don't. Just don't! :smash:), anything really.
As much air as you possible can get behind the speakers!
10cm rockwool on the wall behind your head 1m wide*0,5 meter high, and the head close to the wall (rockwool). Kill the first reflexes on the sides and the floor and roof.

On the electronic side, have you bypassed or replaced the elektrolytic cap?
Do it. Active filter at 120-150Hz and dipole subwoofer.
You can also add a closed box subwoofer for 15-30 Hz.
Cutting off 30Hz and below, really helps your dipole woofers to sing out!
And in small rooms (5meter) dipole stops working below 30Hz anyway.
The cap is an elektrolytic 220uF in parallel with 1,5 ohm resistor.
If you have a tube amp with transformer output, then you can try and just bypass the cap (and resistor) with a wire. It will change the frequency response slightly. But it improves the resolution a lot. And less distortion.
Agree with esl 63, except on the "head close to the wall" part. Experiment here. Head close to wall can add bass level BUT it can also make it muddy. I suspect with Quads bass EQ esl 63 may be right however. All my planers have a larger rise at Fs than Quads so had to get head about 1 foot from wall to be right.

I have a bunch of experience not with Quad BUT with full range ribbon/ planers in a room very close to your room size.

In a room that small u get best sound with speakers between 4-5 feet from rear wall AND your head about 1-1.5 feet from wall behind it. From there space and angle panels and your head too taste.

In effect u end up sitting with speakers almost like a pr of big headphones Ha.

Sure you can get good sound with a less room dominating arraignment BUT, there can be large difference if you let the speakers dominate the floor
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Sadly that won't happen. I get grief if I move the speakers 6" further apart! I can treat the walls, as I can make that disappear. I might get away with moving them forward 6", as they are sitting slightly back on the new sprung plinths, so there is a little leeway there. But the carpet limits forward movement.
An externally hosted image should be here but it was not working when we last tested it.
The secret of the amazing soundstage with planars comes when they integrate with the room. When the soundstage of the speaker blends WELL with the soundstage of the room.
What I have learned thanks to a good fried with similar setup, is to let the room BEHIND the speakers sing!

If you have at least 13 feet or 4 meters behind the speakers, the reflections and the diffusion of the sound will be late enough when it bounces back to you that it will blend nicely with the original sound. It will give air and openness.
If you have a wall behind the speakers like 3 feet, and then is forced to damp heavy, the sound stage is collapsing. I have 7 meters behind my speakers which gives an attenuation that is maybe too big. I try to keep that part of the room free from curtains and carpets and that helps a lot.
The listening area is damped only at the first reflexion.
I recommend everyone to at least try this setup before selling their planars. There IS a huge amount of bass if you let them breath!
In most situation thers a suckout between about 70 and 120 hz due to cancellation from wave bouncing off rear wall in time with front wave.

Once this problem is reduced enough the bass can be very convincing. Only space can do it. No amount of wall treatment can.
4 metres behind the speakers? I just re-measured my room, and it is 4.5m across. my head is 50cm from the wall, so I would be sitting directly between them! And of course, they would then be only 50cm from the other wall! :D
It may well be that they won't work here, and I will have to move on. But I will work on it some more.
wait till your other half goes to the store and then try them at about 4-5 feet out from rear wall and compare to your present location and u will see.

Then u will be trying to figure out how to build a new room Ha

Once people hear planer bass with space ( and its effect on midrange btw) they start thinking about a bigger house
Its a curse
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My best experiece was at a Chicago CES in the 1980's We set up a a pair in a large meeting room, probably 30' (10M) by 50' (15m). We had enough space to set the speakers 10' from any nearby surface and lined up an array of about 20 chairs. The floor was carpeted but no other acoustic stuff in the room. All the seats were good. We did use a subwoofer but did not seem to run out of headroom. Many were very impressed.

Very few people have rooms that big in their homes. Even fewer who could keep the rooms sparsely furnished.

When I have more time I'll outline the things we did in the Crosby Quads.
When I was looking for a new home I went to see many houses.
My prio 1 was acoustics suitable for QUAD esl 63 (or esl 2805)

When I entered the house i´m currently have (and will, until the end i guess...) i went straight to the living room looked around and I said YES! This is a nice house! I take it! Good acoustics!
HiFi nerds are special...
As my room won't allow me to bring the Quads 4 metres (or even one!) out from the front wall, the subwoofer route is the only option, it seems. Looking at Ripoles, Jazzman's double driver version is too wide for domestic harmony, and as I won't be playing loud, I am considering a single driver version, using the same Peerless SLS 315s. And as my available space is tapered, I wondered if there is any reason I can't taper the cabinets at the front, as long as I keep the openings and volumes the same. Like this-
An externally hosted image should be here but it was not working when we last tested it.

I realise the the rear width would actually be different, but in principle?
And looking at the Ripole page here - RiPole Subwoofer Could I simply power the Ripole directly from the speaker outputs of my Parasound A21? I believe it would handle the low impedance, and with a suitable value of inductor could be crossed over where the Quads fall off. I will measure that first, of course.
If it worked, I could then consider plate amps or active crossover later.
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