I Need A Power Amp?

[jimmy m]

OK Peabody and all. I picked up another adcom. This time a 555. I thought I would run the DX9's off the 555 and the RE 30's off the 545. Question. Because I am running off a y-jack and there is only 1 volume control. Will there be a discernable difference between volume output from one set of speakers to the other set? Or maybe at this point I should run both sets of speakers off the 555 and sell the 545 for maybe a different toy?
The 555 is being shipped as we talk.

[Mr Peabody]

Run the RE30 off the 555, the RE30 is only 97dB efficient and run the DX9 off the 545 it is 101dB efficient. There still might be some difference but this set up should help. The speaker at 101dB will play louder than 97dB with the same input power. You can try using just the 555 but I think running two pairs of speakers you have an impedance issue not a power issue. Unless you have a huge room I'd think just one pair with the 555 should give you plenty of SPL. If you are going to use both sets use both amps I think you will be happy with the result. I would also try going straight from the preamp first then add the EQ to see if the EQ is causing any issues. Sometimes when you want a hard hitting bass try turning the bass down. The largest mistake I see with subs or back when EQ's were popular guys always thought more is better, but what happens is the bass gets over driven and murky, it loses detail and the amp loses any reserve power. So back off the bass and lose the rumble and gain some punch. If your preamp has a "loudness" control, turn it off when listening at high volume. Good listening and let me know how the set up works out.

[jimmy m]

You are so entirely right about the sound. Now the problem is no matter what I do there is absolutely no punch from the bass.

[jimmy m]

OK, I reconfigured. Now I'm going directly from the preamp to the power amp and added the EQ to a different loop. It seems to help. I can just turn the loop off if I choose. I like this setup better. Sounds better too. Also now it will allow me to go directly to the 2nd amp by means of an autobridge input, rather than coming off the EQ with a y jack to accomodate both amps.
Really and truly I'm still not completely satisfied with the bass. It just seems like the bass should be crisper or cleaner with that thumping punch. I just can't seem to get it.
I had a buddy tell me I need a seperate subwoofer speaker. The speakers I have it seems should be capable of putting out the bass I'm looking for. What do you think? Any more ideas or solutions.

[JoeE SP9]

Not to sound like a spoilsport but, is the sound you're looking for actually in your source material?

What specific piece or pieces of music sound deficient in bass to you? If you're listening to modern popular recordings most of them don't have any low bass. Most rock recordings of the 70's and 80's are also in that category.

[jimmy m]

Yes Joe, the vast majority of music is rock related stuff. But I mean even reggae, which typically has a lot of bass sounds muddled to me. It just seems like it should be more crisp. I don't know how else to describe it.

[Mr Peabody]

Jimmy, are all the speakers in phase? Meaning make sure red (+) on the amp is to red (+) on the speaker and same with black (-). A speaker out of phase will decrease your bass response.

I'm not sure where the problem is but I can tell you it's not the Adcom amps. Do you have the same problem with just one pair of speakers working? If your speakers are decent you should be getting romping bass, 12's & 15's driven by Adcom..... Also, try with just one amp hooked up it could be the preamp output doesn't have quite enough voltage to supply to two amps. Subs typically are for very low frequencies and won't help much in midbass punch.

[JoeE SP9]

Have you tried it without the eqaulizer?

[jimmy m]

OK Joe, I attempted that by actually not running the preamp through the eaulizer to the power amp but rather the pre to power amp adding the EQ in on a seperate loop from the preamp where I can either run it or eliminate it. You are the guy to ask if I was to add a sub in the back would that ruin the imagery? I mean the DX9 has a 15" woofer and the RE-30s a 12" which in my estimation should be substantial without adding a sub. I can pick up a Paradigm PDR12 for a reasonable price. Or even a Bic 12. I really don't know if it is necessary.
And yes Peabody everything is copasetic as far as being in phase. Maybe there is to low a frequency and I am tring to obtain more of the mid bass punch, sounds right. I could hook up the old Marantz as a seperate pre amp so each amp has its own power amp. One with the Souindcraftsmen, and one with the Marantz.

[Mr Peabody]

No, do not hook both the preamp and Marantz at the same time, always only use one or the other. You should try the Marantz preamp outputs though to see if it's a better sound than the Soundcraftsmen.

I have not heard those speakers before but have been told they are Disco/R&R speakers/frat party etc. So it's hard to imagine what the problem is. Adcom is known for having heavy bass response. Where are your speakers placed in the room?

It could be that although the CV are efficient you aren't getting good quality low impact, a sub may help, any way to try before buying? You'd almost have to use the speaker lead connections since already running two amps.

[Mr Peabody]

One other thought, are your amps plugged directly into the wall? Sometimes those AC filtering devices limit current which starves a power amp.

Also, remind me what you are using for CD playback.

[jimmy m]

Its just that the Soundcraftsman is so much more versatile where I can't do everything I want to do through the Marantz (like adding in the Eq if I want. The Souncraftman as a ton of inputs and capability to autobridge the 2 power amps. Although using the Marantz bare without the EQ, yes I'm sure it has better sound - deeper.
The amps are plugged directly in the wall. The cd player is a Denon CDR W-1500.
Don't misinterpret me on this. I mean I get alot of bass response. But to me it doesnt sound real where someone is standing in front of me playing a bass. It just seems muddled and doesn't have that pulse or push from a bass guitar. I think its lacking in mid bass possibly, if I'm understanding what your saying.
The speakers are placed about 10-12' apart stacked for the imagery, which I do get now (Joe). And they are out from the wall about a foot

[jimmy m]

If you mean the speaker lead connections from the sub, I could also get around that by running it through the adcom speaker selector switch I have which I no longer use.

[Mr Peabody]

What does that "auto bridge" do? I haven't heard of that and wonder if that could be an issue.

If the Marantz has a "tape monitor" which I'm sure it does, you can easily hook the EQ into that. Tape monitor on, EQ in the signal path, tape monitor off, EQ out of the loop.

[jimmy m]

It just allows me to hook up 2 amps at a time through another set of inputs for amp connections specifically. At least that was my interpretation. I was running one amp before with no problem through it with pretty much the same results. As far as the Marantz goes, I've pretty much exhausted the inputs with a tascam 202mkIII and the cd player in tape2 since its old enough not to have a specific input for cd. Phono Yamaha YP-D6 and Dynalab FT-101 (not the etude dang it) still nice in the other inputs. The Soundcraftsmen isn't the problem,its fine.

[Mr Peabody]

I tried to find some info on the auto bridging but no luck. What worries me "bridging" means to make an amp mono. One thread I found led me to believe that feature requires an additional module but couldn't be sure. If the preamp has a regular output you might try it to see if any difference. From comments I found it does seem the Soundcraftsmen are decent, your EQ should also have some type of lighting system which helps not to overdrive or clip your amps. Another guy mentioned the phono stage was a weak point, saying it was harsh. Keep in mind these are comments from other forums.

[Jim Eck]

Here is a good source of information about your Adcoms. http://www.adcom-usa.com/adcom-user-guides

I agree with Mr. Peabody, typically when you bridge an amplifier you are creating a mono-block that will power only one speaker.

I am curious about your Cerwin Vegas, both models you have have some age to them, unless you have replaced the surrounds I would suspect that at best they are weak, they could be bad, both models use the foam type surrounds and are known to sufer from foam rot, also you might check to see if the voice coils are still strong. I have an old pair of HED's that the voice coil got weak enought that it would rub, inverting the speaker helped but did not fix the problem. Replacing surrounds is an easy fix, there is a lot of information on doing the repair yourself, as well as many places to acquire the required surrounds.

Most amplifiers don't perform well if you must turn the volume up past the 12:00 position, you are probably under powered for what you are trying to accomplish, the bass will sufer first, you will also begin to clip which is not good for the amp or the speakers, dirty ower ruins more speakers than overpowering them with clean power.

You might consider selling one of the Adcoms and replacing it with one that matches the one you kepep, then only run one set of speakers but do then bridge the amplifiers into a pair of mono blocks, this will greatly increase your power output and increase your bass response.

A GFA 555 is 200 wpc into 8 ohms that is a considerable amount of power, a pair of Adcom 555's bidged would be 600 wpc into 8 ohm, I have a pair of briged Soundcraftsmen 860's into 600 wpc, you should never find out what the pair are able to do, I use the two to DJ at a local bar and have never even come close to the 600 watts.

Good luck, Jim

[Jim Eck]

Something else that might help is to tip the speakers back (your DX-9's), not a lot but maybe put a 2X4 under the front of the speaker to tip it back, don't let it be against the wall, see what you think, it will change the sound.

Jim

[jimmy m]

Thanks Jim. When I take the grills off the front of the speakers, they look brand new. I mean I dont see a single crack or wear, dirt, dust, or anything in the surrounds. But maybe its a problem you cant visibly see. That is always a possibility, and worth consideration. As far as tipping them back, right now they are stacked for imagery and sit like 6' or more tall. I know what you're saying though as far as changing the sound when tilted.
As far as the autobridge, what it says is where I run the (line out normal) of the preamp to the power amp; there is another (line output inverted) that runs to the second amp. Each power amp has its own set of speakers.
I'm starting to wonder if the problem is with my hearing, jeez. I just don't feel the bass, like I think I should.

[JoeE SP9]

Try putting a couple of cinder block under each stack. If they do the trick you can then invest in some stands. Virtually all "bookshelf" speakers sound better on stands that elevate them so the tweeters are at ear level when seated,

The autobridge is for another identical amp. Don't attempt to use it with any other amps. It allows you to run two identical stereo power amps as mono blocks. In the best of worlds bridging an amp should result in an output four times the single channel output. Doubling (that's what happens) the voltage swing means four times as much power. In the real word (most amps) you'll get around three times the single channel output.

[Mr Peabody]

JM, try hooking only one amp into your normal preamp output and then try hooking the same to the "inverted" one to see if you hear any difference. "Invert" means to reverse, I'm really wondering about the hook up. You could even try hooking your Y adapter into the normal output to see if things improve.

[jimmy m]

So by no means hook up an amp to the normal and the other to the inverted? Am I going to fry something or what is going on? The amps have to be exactly the same? I mean if worse comes to worse I can go back to the y idea. And I guess I can always sell the 545 and look for another 555, in which at that point I probably only need the one amp.

[Mr Peabody]

You said you have an issue with your system, I'm merely suggesting things you might do to find out what the issue is. Naturally, if one output is one way and the other says "inverted" that would throw up a flag. It may not mean anything but you won't know if you don't experiment. You can't be sure it's correct nor could I find any info on that "bridging" feature. If you are satisfied with your system or tired of dealing with it just say so.

It makes absolutely no difference what so ever using the two different models in regards to your bass issue. If you hooked them up as I suggested, the most powerful amp to the least efficient speaker then you should be able to tell by listening if there's one set still drowning out the other, you may have to stand in front of them and move your head up and down to each to evaluate if they sound about even. One amp on one set of speakers is the safest way to go. With the CV's sensitivity and the amount of power you have they should be hearing your system on the next block.

Just guessing again at the inverting thing but if that is referring to phase your top set of speakers may be out of phase with the bottom which would decrease your bass quality significantly.

[harley .guy07]

I have personally heard the DX-9's off of both a 555 and 5500 adcom and 2 pairs running off of a 5800 and believe me that when I heard them bass was more than plentiful!!!. almost too much for some music but the customer I had at the time wanted that PA system type of sound with a lot of power and that is what he got(and everyone on his block).

[jimmy m]

I do understand Peabody. I got a little apprehensive when Joe said not to use the pre without having 2 amps of the same. The only reson I haven't already tried the various combinations is I have this idea that something will shell due to my stupidity. But now I feel more confident and I'll let her rip. Yes I will take your advice and Try to discern between every combination humanly possible. I'm sure I'll hit upon something to my satisfaction at some point. Being a perfectionist really sucks. When I strike gold you will be the first to know. Thanks again so much for your help. I hope I didn't offend anyone. Everyone has been great.