[bosjohn]

Hi my name is John and as is obvious I am new to this forum. I have built the GR Research av3's about three or four years ago so I am not new to speaker building and woodwork nor to GR research. I have several possibly unrelated questions about my speakers and other GR research items so I don't know if they should be lumped together here in this post or not. I am sure someone will tell me:-)
First while over all I am very happy with my speakers I can't seem to get the base response where I think it should be with the tone controls anywhere near flat. The speakers have gobs of base I have heard it but seem to need the base boast from the amp to get it. I have tried them with several different amps and in several different rooms and various distances from the wall. The different rooms made the biggest differences. Presently my amp of choice is my Unico hybrid which, sigh, has no tone controls.  My other amps include a heavily modified dynaco st 70 and pas 3 not modified and a few nad 20's, oh I forgot also a dynaco sca 35.
Any suggestions short of a subwoofer?
Seeing as how this is getting too long I will start a new post for the other questions. Thanks for reading John

[HT cOz]

Have you measured your in room response?  Our ears are way to subjective to really figure out what is going on.

[bosjohn]

Nope I have not as I have not been able to find my spl meter since I moved here to california. Once I locate it and get a new mic I will do that.
Thanks John

[bosjohn]

I have now done a preliminary measurement in the room with the av/3's. I am using a radio shack digital sound level meter.
at one meter at an medium volume level I get the following which is abbreviated. The left speaker started at 500 hz gave a reading on the meter of 75 dbs the right 67 at 250hz 61 and 61, at 200 65 and 59 at 150 63 and 65, at 100 58 and 69 at 75hz 61 and 65 abd at 50hz 51 and 56. so with this amp and this room my speakers seem to loose abouat 20 dbs from 500hz to 50 hz wow that seems like a lot. Nest test I will reverse the speaker leads. Any insight would be welcome.
John

[Danny Richie]

Reversing the speaker leads? Were you shooting them both playing at the same time?

[dBe]

I have now done a preliminary measurement in the room with the av/3's. I am using a radio shack digital sound level meter.
at one meter at an medium volume level I get the following which is abbreviated. The left speaker started at 500 hz gave a reading on the meter of 75 dbs the right 67 at 250hz 61 and 61, at 200 65 and 59 at 150 63 and 65, at 100 58 and 69 at 75hz 61 and 65 abd at 50hz 51 and 56. so with this amp and this room my speakers seem to loose abouat 20 dbs from 500hz to 50 hz wow that seems like a lot. Nest test I will reverse the speaker leads. Any insight would be welcome.
John

What you are seeing is classic room mode cancellation and the RatSnack meter is not accurate below 250Hz.

If your speakers are not set up symmetrically in the room, you cannot get a reading that will correlate.  In order to get some semblance of accuracy, you need to measure the low frequencies from at least 10 -12 positions in the room and then average the results.  Even then, all you will get is an *idea* of what is going on in the LF.  To accurately measure below the Schroeder frequency in room requires a gated and windowed computer based system.  The meter will not do what you need.

What are the dimensions of your room and where are the speakers located in the room?

Dave

[bosjohn]

Reversing the speaker leads? Were you shooting them both playing at the same time?

Yes I had both speakers sounding at the same time. I also tried other distances and angles from each speaker as well as centered between them and got mostly similar readings. Now I moved the speakers so they are now against the short wall about two feet from the back and about a foot and a half from the side. There is some improvement but the base is still down. I know the radio shack isn't the best meter out there but its what I have. When I play them side by side so to speak ( I actually sub one speaker for the other in the same position) the elons have much more thump in the bottom but their half powr point is higher and I am aware that most smaller closed box speakers have a bit of a hump in the upper base as part of the box size and roll off trade off.  The only other thing I can think of is I may have over stuffed the speakers.

[Danny Richie]

Okay that could explain a lot.

It sounds like you have one speaker or the woofers in one of the speakers out of phase.

Try doing these two things.

One, measure each speaker independently and see if the bass response is then level.

Secondly, flip the polarity of one of the speakers and see if it picks up.

[bosjohn]

I had not thought of that I will check that out now thanks

[bosjohn]

Okies I checked the phasing of the drivers. Each pair of drivers that is the pair in each speaker move in the same direction when a aa battery is put across the terminals. Each pair in each speaker move in the same direction when the negative of the battery is put to the red lead on the speaker etc. They appear to be phased correctly.  I eliminated the banana plugs and anything else I could think of and I got some base. Not bad but still not that thwamp that the elons have. Maybe thats because the elons are closed box speakers and since I had to have them reconed  by repair person who didn't seem to understand that re-coneing with a stiffer cone or pick a paramarer can raise the box resonance and produce a more pronounced hump in the base. Maybe thats what I am hearing. As I mentioned before I know the my a/v3's have a very good bottom end I just don't know where its hiding right now. The problem now is that about the only place I can put these speakers may not be the best for the sound. they are in front of a built in book case against the long wall of my living room which is open to other rooms at each end and halways on either side of the book case. The speakers are about 28 inches out from the book case. So it looks like I need a subwoofer or use the amp with the tone controls or get a good graphic equalizer(shudder)

[corndog71]

I would add a sub before any eq or tone controls.