high end stereo question, single pre-amp out to double?

Off-topic
1

hello,

So once again, I’m comming to the brightest minds on the internet to ask a question I can’t find the answert to:

So I finally got a job doing some engineering work, and because I have some spare change, I’m going to put together a nice stereo.

I have:

2 - marantz 500 monoblock amps. 125W @ 8 ohms, 180W @ 4 ohms
1 - heathkit reciever with a dual channel amp, which I belive is 125W x 2 @ 4 ohms

I’m going to build 2 - 3 way speakers, for a nice stereo set up. mostly I’ll use it for records, and CD’s, although I’ll probably get a second reciever for video stuff and output the audio into the heathkit.

If I only have 2 speakers, what am I using all those amps for?.. I’m going to bi-amp the speakers. The plan is to use the Marantz amps to power the single woofers in each speaker, and the heathkit to power the mids and tweeters.

The problem is that the heathkit only has a single pre amp out, so If I want to use it as the reciever as well, then I need to somehow split that into two pre amp outs. Anyone know if this is possible, or if it’s a good idea?

My other option is to buy another reciever, basicly to use as a source switching box. It would need to have at least 3 pre amp outs, and a phono in. I don’t have a decent record player yet, but it’s my understanding that most of them need another amp that is usually built into the reciever, if it has a phono in.

anyways, any advice? Thanks.

2

You can split the pre-out to multiple amps, but it would likely degrade the signal, so not really recommended. Although, it’s not clear why you need to do so. The heathkit can drive the top end, then you can use the pre-outs to the monoblocks for the low end. …OR are you saying that the Heathkit is two boxes (pre-amp/power amp)?

You might have a hard time finding a pre-amp/pre-processor with three sets of pre-outs…again, it’s not clear why you need that since you only have two amps (if you think of the monoblocks as a single stereo amp).

I’d additionally add that early solid state amps (assuming the Heathkit is solid state) didn’t really sound very good. You might be better off just using the monoblocks and forgetting about the output stage of the Heathkit.

3

To do this right, you really need a crossover…

What a crossover will do is split the signal based on frequency. In your case, you would find out which frequencies would be best for your tweeter and midrange, and send that to one amp, and then take the bass and send it to your other amp. You’ll need a stereo crossover to, well, do it in stereo.

I am not sure it makes sense to get into balanced signals and DB/Octave rolloff in what you are doing. Most crossovers you can get at guitar center or something like that would be installed before the amp, usually on XLR or 1/4" cables.

It sounds like you are building your own speakers, so I assume you won’t have a passive crossover built in. If that’s the case, you would probably do better with just a 1" tweeter and a 12" or so mid/woofer, and then biamp that (after a crossover). Hooking your two smaller speakers together would send the full range from that amp out to both, making both of those try to reproduce sounds they aren’t real good at.

Also note, that just like most anything… really cheap crossovers sound really cheap… :wink:

Keld

4

it’s possible that I’m not being clear (I don’t think I really explained myself as well as I should have), or that I’ve been thinking about this wrong.

I had considered the fact that I would need crossovers, I had planned on using one 2 way electronic crossover before both amps, and then a passive 2 way to seperate the mid from the high after that higher end amp. 4 total crossovers.

After reading both your posts though, I’ve kind of re thought this.

-If the heathkit is solid state, and doesn’t sound great, I’ll use that to drive both the woofers and each of the mono amp’s to drive one channel of the mid and high speakers.

-since I need an 2 way electronic crossover AFTER the source (to set up an effective biamp system) I can’t use the heathkit as both the amp and the source.

-so I do need a new reciever with 3 pre amp outs (heathkit, marantz, marantz), and a phono in.

I got my info on bi-amping from: http://sound.westhost.com/bi-amp.htm

Please let me know if I’m wrong about any of these assumptions.

I’m at work now, but I’ll upload a diagram of what I think the diagram would look like as soon as I get home.

Basicly it’s

…Source (Reciever)
…|…|
… |…|_
…|…|
…|…|
…Left Channel…Right Channel
…Electronic Crossover…Electronic Crossover
…|…|…|…|
…|…|…|…|____
…|…|…|…|
…|…|…|…|
…Marantz Amp…Heathkit Amp…Marantz Amp
…125W x 1…125W x 2…125Wx1
…|…|…|…|
…|…|…|…|
…Passive Crossover…Woofer…Woofer…Passive Crossover
…|…|…|…|
…|…|…|…|
…Tweeter…Mid…Mid…Tweeter

(All the periods… are just placeholders to keep formatting, I hope it works)

If that comes out clearly, then will that work? I know that it’s a basic and dumb question, but does anyone know what kind of connections I’ll need on all those components? (like for the heathkit do I need 2 sets (R + L) of pre amp ins, and then I need 2 sets (R+L) of speaker outs.)

For this setup it looks like I just need 2 pre amp outs, one for the left channel and one for the right? Any reccomendations on where to get a good reciever, with a phono in? doesn’t need to have any built in amp.

Anyways, thanks for taking the time to read this and help out, I appreciate it.

-Nick

(edited for formating twice)

5

Ahhh… good… yes… your diagram looks right…

Your source just needs a left and right out… correct.

Your heathkit needs 2 ins and 2 outs…

Each of your Marantz units need one in and one out…

Each crossover will have one in and 2 outs… (tho you could use a stereo electronic crossover, and it would have 2 ins and 4 outs…)

I really don’t know much about receivers and stuff… I’m a sound guy for concerts and churches and stuff… so I come from that background…

-Keld

6

The term “reciever” as it’s used in home audio, refers to a single box, that contains a radio tuner, pre-amp (volume, source selecter, tone controls),a power amp and a theater processor (if it’s a home theater reciever).

I think your heathkit (i could be wrong) is an “integrated amplifer” which contains both a pre-amp and a poweramp, but not a tuner.

I think what you’re looking for is just a pre-amp (or processor if you’re doing home theater) with two stereo pre-outs. You don’t need three sets of pre-outs, since your Marantz amps are effectively a single stereo amp.

Also, depending on why you want to design your own speakers, you may be better off keeping your system simpler. Take the $$$ that you wind up spending on crossovers and put them into your other components (speaker, pre-amp, etc) and you’d likely end up with a better sounding system. What you’re doing is some pretty tricky stuff, and it’s easy to spend a lot of money and wind up with disappointing results.

Of course, if your goal is to learn about speaker design, that’s a different story.

7

Bi-amping can be beneficial. There is a reason that even low end powered studio monitors are bi-amped. If I was setting up a speaker system for myself it would be bi-amped.

Whether it is the most bang for the buck to spend more on speakers or amplification or source is always up for debate. Optimizing for bang for the buck is tricky. It is better to optimize for enjoyment, what suits you, and what equipment you have available.

8

A receiver would include a radio. Do you want the radio with it built in?

An inexpensive basic preamp with a phono input is the T-preamp: link1 link2
Course there are better preamps with phono inputs, but they can get expensive. Another option is to get a preamp that doesn’t have a phono input and use a separate phono preamp. There are also turntables now that have built in phono preamps so they connect to a regular line input on a preamp or receiver.

9

i just want to say that the TCC TC-754 that john_childs is a very poor product in my personal opinion.

i don’t know if it’s just chance but i got one of these and it just stopped working after a month or so.
i would take to get repaired but the cost of repairing this thing is much too much for me!
Johnny from guitars101

10

Does it have any kind of a warranty period?
I have never used the T pre-amp. It’s just a low cost option that has gotten fair reviews from the audio press.

My current favorite pre-amp is the Mackie Big Knob. It’s not a traditional home pre-amp but works nicely for my setup.

11

wow I’m kind of impressed and very amazed to find a conversation like this on a unicycling site! you guys talk about everything here, I guess. hi there btw, I’m new -

(_/)
O 0
(><)This is bunny. Copy bunny into your signature, help him on his way to world domination.-blackdiamond13 @ Jemsite

12

Welcome.
One wonders what you were searching for to get this thread. You’re going to fit in well around here.

13

Congratulations also for getting JC up off the bench. He had successfully killed this thread when you brought it back to life. So he had to take another crack at it, but then I came along.

I can’t split signals or any of that stuff, but I like to think posting in a thread like this gives me some sort of audiophile cachet.

14

Seeing as this thread was already bumped why not reply now, several months later…

Passive crossovers are fairly cheap at radioshack, and high end ones can’t be that much harder to install. I built up a pair of speakers when I was 16 complete with tuned ports, passive crossovers, and fuses. They still work great 11 years later. I don’t see why he can’t throw in a set. If he can do the math the comes with building a properly tuned speaker box then wiring a crossover is easy.

15

Hooray for ancientness…

I am just used to the world of biamping and triamping speakers externallly, from an external DSP box. So when someone talks about crossovers and stuff… that’s where my mind jumps to. Installing a passive crossover in a speaker box is probably easier than installing the actual speakers.

I am not a major player in the world of pro audio by any means… But if you have a company like EAW or JBL or EV, their higher end boxes usually use external crossovers and processors. The speakers at the venue I do most of my sound at are Tri-amped EAW 850s… no internal crossovers… That is the perceived higher quality…

Of course, this is not a hard and fast rule. Companies like Danley and D&B make very very good boxes using internal crossovers that also correct for timing, phase, and EQ.

Anyway… hooray for rambling…

16

Your sub stage looks weak:p

17

To those who may be curious:

I gave up on bi-amping and just built huge 3 way speakers; each has two 12"s, a mid and a tweeter.

Right now I’m powering them through a 300 x 2 QSV amp; I disassembled my home audio stuff, and went pro.

It is very loud, and very clear. Sounds fantastic.

Thanks for all the help though!

18

The pro side of audio is interesting as well. The focus on the pro side is different than the home audio side. The hi-fi end of home audio gets to be a little weird while the pro end of audio stays focused on what it takes to make good sound.

For nearfield monitor listening I like the pro audio end of things better than the home audio end of things.