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Can I "Gang Up" Cheap Amps to Make Big Power?

 

New member
Username: Wetbass

Post Number: 2
Registered: Nov-04
Hi all:

I'm no audiophile, but I know I like what I can't afford. My goal is to combine or "gang" cheaper, lower-output amps so as to come up with big watts. Then, I thought I could spend money for good speakers, having created the watts for next-to-nothing.

I have a 200w amp (can't remember the brand) and a 165w Toshiba SA-3500. I paid $10. for the latter, with speakers, at a garage sale, which gave me the idea. For argument's sake, assume they're both 150watt amps (total), so that they can provide 75 watts per side, each.

I know I could "bridge" their left and right channels, creating 150 channels, one from each amp. I don't know how to do this, but I assume you wire the left and right outputs together, switch the receiver to "mono" and only provide one channel of signal--is that right?

Can these "bridged" amps be used to put 150 watts into each of two signals (say, the left and right from a CD player)?

If so, here are my additional questions:

1. Can this be done multiple times, so that I could build a rack with three nonidentical, but equal output amps (say, 150 watts each, total) PER SIDE, for a total of 450 watts for left and 450 watts for the right side?

2. Does the harmonic distortion of each amp get added to the final product, so that if it were .1% for each amp, then each side now has distortion of .3%?

3. If each 450 watt "stack" or channel was made up of differing output amps (say, a 100w/100w/250w for the left, and a 75w/125w/250w for the right) would it matter?

4. If the amps' total outputs didn't equal each other, so that the "left stack" had 425 watts, and the "right stack" had 500watts, would it matter? Could I compensate by reducing the volumes on tne higher output stack?

5. Is there a central "controller" that could be employed to provide one-knob-volume control, i.e., leaving all six amps all the way up, or up to their individual clipping thresholds?

6. How would one get the left/right signal from an XM radio or a Discman to each of the three amps in each "channel stack"?

7. How could this system easily be wired to power four speakers instead of two?

8. If this is possible, why doesn't everybody do it?

9. If it's possible, what major pitfalls am I unaware of?

Thanks in advance.

 

J. Vigne
Unregistered guest


" ... what major pitfalls am I unaware of?"


Things blow up and things sound bad. Other than that you've pretty much got it covered.



 

Gold Member
Username: Kegger

MICHIGAN

Post Number: 1841
Registered: Dec-03
Steve Storm:

I'm sorry there are so many things wrong with what
you want to attempt I can't even begin to start!

And you don't need large watts to start with to get great or even loud audio.

Most people don't even use 50 watts of what they have!
And the more efficient your speakers are the less watts you need.
"It would take 4 times as many watts to drive a speaker with a sensitivity of 86dB than it would one with 92dB. You have to double the watts to get a 3dB increase in volume.

A sensitivity rating of 86dB means the volume level is 86dB if you're standing a meter away from the speaker and if you're providing one watt of power to the speaker.

The lower the resistance to your speaker, the more power that is applied to it (power = voltage^2/resistance). However, the amount of current will also increase. When going from an 8 ohm speaker to a 4 ohm speaker, the current will double. If your amp can't handle that, it will overheat and thus ruin the amplifier or it will go into protection mode."

(lookup speaker efficiency) and db ratings on speakers.


most amps (home anyway) can't be bridged or tieD to the output of another.
 

New member
Username: Wetbass

Post Number: 5
Registered: Nov-04
J.Vigne:

I've really enjoyed reading your posts. You write so accessibly that I can understand most of what you say even without having much of a background in this stuff. (I read, and understood, one good-sized book I got from Crutchfield, on building car audio, but it was 3 years ago, so I've forgotten much of it.)

Neverthless, I did have this idea about "ganging" the amps, and something I saw from "Charles" in a post about using car components in the home made me think my idea would work. He stated "[Y]ou could connect a bunch up in parallel and get there but.....I'd rather not."

I was trying to find out if you guys thought this would be a feasible option, however, your response seems to indicate it is not a worthwhile pursuit. Is that what you meant by "Things blow up and things sound bad. Other than that you've pretty much got it covered."? I don't so much care if things blow up, but I really didn't want it to "sound bad."

I seem to have offended you, J.Vigne, so let me apologize. It was not my intention to annoy perhaps the most knowledgeable audiophile I've ever had the pleasure of reading. Your discussions in "The British Sound" thread alone were absolutely fascinating.

I was just hoping to use some of my low brow skills to make up for what my bank balance will not allow, and coble some smaller amps into something that would make me want to spend real money for decent speakers.

KEGGER:

When you say "I'm sorry there are so many things wrong with what you want to attempt I can't even begin to start!," I, like Bill Clinton, "feel your pain." After all, I wrote it! LOL.

I believe I know [i]exactly[/i] how you feel, as I'm much more knowledgeable about automobiles than stereo. (I actually turn wrenches for fun, and have been employed in the auto biz for a number of years). Sometimes, you don't even know where to begin with someone whose enthusiasm grossly outweighs their command of the technology, which is almost nil. I'm sorry to have to be that person in such an equation, for you--believe me!

So I thank you for taking the time to get me headed in the right direction. I guess this is an example of karma in action, as I have started from scratch with hundreds of ignorant auto customers, re: service issues. With automobiles, it may be even worse, as there are MANY myths people were told by their fathers, and "know" to be true, which are in fact very false. You have to "unlearn" such customers before you can even begin to teach them anything.

I seem to be suffering from only one such myth, i.e., I labor under what appears to be an incorrect assumption that I would need big watts (200 per side, and up?) to make good, loud, CLEAN sound?

Btw, re: your distinction between "great or even loud" audio, let me be clear: I have no interest in merely "loud" audio if it's not clean. When I go to see a bar band, 9 times out of 10 I have a conversation with the sound guy/gal, and ask them to turn down the ear-splitting treble, reduce the grotesquely overblown reverb, and bring up the vocals, (typically) so that the music is not damaging, and I can actually hear individual instruments/vocals. I usually get thanked for the feedback, both by their adjustments, and in words. If they are unwilling to make it listenable, I am unwilling to stay. (Friends of mine had a band, which I saw dozens of times, and we learned how to help them tune their sound for various spaces. I believe their monitors may blind them to being able to hear what is going on in the larger space--for whatever reason, many musicians and soundboard types are appreciative of such feedback, in my experience.)

So distortion I don't want--I can get that now by turning up my 165watt Toshiba too much--lol!

I appreciate your review of speaker sensitivity and impedance's effect on amp current. And re: the formula of doubling the watts to get a 3db increase in volume, isn't it true that a 3db increase in volume is the smallest increment we can actually notice? I seem to remember that...

Thank you for the suggestions for further reading--I will do so--I assume you meant me to do a search on this site, for those topics?

Why is it that "most amps (home anyway) can't be bridged or tieD to the output of another."

Also, I have four big speakers in my living room, currently running off of the 165 watt Toshiba amp. I wanted to maintain all four, (possibly even replacing them with better speakers) and that is one reason I thought I would need more watts.

Isn't it true that the higher the watts (up to the rated capacity of the speakers, of course) the louder the CLEAN sound they will be able to reproduce?

Thanks for all of your help. This is truly a wonderful forum, and I'm sorry to be so uninformed. I will endeavor not to start any more posts from such a position of ignorance in the future, but I am curious to know more about this one, if in fact I should be looking out for multiple, cheap amps to hook together, though it appears this is folly on my part.

Oh! If it IS feasible to "gang up" several smaller amps, does this multiply each amp's harmonic distortion, so that three amps would have three times as much distortion as one? Still curious, even if it's a fool's errand.

Thanks again.
 

Gold Member
Username: Kegger

MICHIGAN

Post Number: 1844
Registered: Dec-03
Steve Storm:

"Isn't it true that the higher the watts (up to the rated capacity of the speakers, of course) the louder the CLEAN sound they will be able to reproduce? "

Basically the power rating on speakers is the max they can
handle before blowing up.
So we don't want to run at or near there rated power or they won't
last very long.

If you've got a pair of speakers that aren't very sensitive "around say 84db"
Then yes your going to need pretty good power to drive them to higher levels
and not have the amp run into clipping so it sounds better.

But if you have sensitive speakers "around say 90db"
Then you can use a much smaller amp to get the same amount of volume.
And by using a smaller amp it's cheaper to get a better one versus a good
high powered amp.

So agian you don't need a giant power amp to get good quality and or
loud volume from your speakers.

Some people run "high end" single ended tube amps at 8 watts a channel
and get plenty of volume with awsome sound!

So it comes down to what your existing speakers are "sens and impedance"
Or what speakers your looking at purchasing to decide what amp/power
you need.

Or if you have an amp in mind then get speakers to suit your needs and wants.

Basically the speakers and amp need to be thought as a
working tandem for best results.

Some speakers do some things well and some amps do other things well.
So you try and match up there strengths and weeknesses as best you can.

That's what I meant by doing research on the things your looking for.
"on the net and on these forums"

Noone is going to know all speakers and all amps
not to mention what is available to you in your area.

And what you like to hear in your speakers is different from someone else.
Different types of music "can" point towards a certain type of speaker.

So you really need to go do some auditioning of products based
on your needs and wants.

Then when you have more specific questions maybe we can help.

As far as why you can't bridge most amps you got me I'm no engineer.

If you read through this whole thread you'll find some excelent knowladge!


 

J. Vigne
Unregistered guest


Steve - You didn't offend me. I'm sorry for the short, curt answer but I didn't have time for much more. And thank you for your compliments. I try to make as many answers as possible mean something. Your question was one of those that, as Kegger said, had so many misconceptions that there was no good place to start.

Many amps can be bridged into mono. Amps with separate power supplies for each channel that share no common ground point will not tolerate channel to channel bridging. Any other amp that can be bridged will either allow it with a simple configuration on the amp's front or rear panel and will include directions for this function. If the amp does not provide the easy bridging capability then you can only do bridging by making connections internally. It is a job that requires knowledge of the circuit and not something you will just try to figure out. Each amp will bridge differently so there is no one way I can give you. The better assumption is that if the manufacturer did not provide for bridging then the amp is better off left in stereo mode. The power supply may not be stable enough to withstand the extra strain of bridged operation. Typically you want to bridge an amp by hooking the channels in parallel and this will cause more current draw from the power supply. Not many amps like extra current draw.
I would suggest you go to the "speakers" portion of the forum and look up the thread "defintions and descriptions". I started it to get some often asked and often misunderstood concepts tucked into one place where anyone could access an answer without constantly repeating the same information. If you have something you would like to ask in that thread, feel free. I tried to keep it a general purpose question, no answers to what should I buy type questions. I think if you read the lay out of that thread you will see how the format is approached. Ignore the round of silliness that went running through the thread; it came from nowhere and consumed the thread. You will find more information on power and speaker efficiency in that thread that you might find helpful.

"Isn't it true that the higher the watts (up to the rated capacity of the speakers, of course) the louder the CLEAN sound they will be able to reproduce?"

When you listen to different quality levels of products in audio shops you will find that watts are not that important. The general quality of design and manufacture are much more important than the on paper specs that many people use to judge amplifiers. In automotive terms wattage is the horsepower, amperage is the torque. One gets everything moving while the other maintains what is in motion. But to assume you need wattage is the same as assuming you need a V8. I wouldn't mention that idea to a Porsche, Honda or Subaru owner. And then you have amplifiers that defy the "common knowledge" such as tube amps that run low wattage , low current and have many devotees. In general, speaker efficiency is the key to volume. Volume is not the key to quality as you are aware. My advide to you is to keep asking questions and to listen to as many different opinions on audio as you can find. Listen to as much audio as your location allows. The stuff at Best Buy and so forth is pretty run of the mill. If you have a high end shop of any kind in your area I would suggest you visit them with a few CDs in hand to hear what better hi fi sounds like. Most good shops are glad to educate someone if you stop in when they are not busy. Don't go on a Saturday and expect too much time from a salesperson. Go on a Wednesday and just poke around listening to what they have playing and then engage a salesperson in conversation. Be careful, just because they are in a fancy store doesn't mean they know as much as they let on. But as you listen and read and ask questions you will start to find who will give you the best answers for your situation. Any salesperson who tells you a certain piece of equipment is junk or seems too dogmatic about their attitude is one you want to avoid. They should be able to back up a statement with something other than "because".

As far as ganging up amps you will end up with increased distortion. Particularly if the amps are hooked in parallel. Most decent amps are not going to have audible distortion in the sense that the music is hard and raspy and obviously distorted. 0.01% THD is considered inaudible. It might suprise you to know that most speakers have far more distortion than alomost any amplifier you would purchase for home audio use. A woofer can have 10-20% THD at its frequency and power extreme. So if you're hearing distortion from your amp, you are driving it into clipping and you will need to address that problem first.

Finally, about 1 to 1 1/2 dB is considerd the threshold of audibility. That is why many volume controls operate in those same steps.





 

J. Vigne
Unregistered guest


Definitions link:

https://www.ecoustics.com/electronics/forum/home-audio/67821.html


 

Gold Member
Username: Kegger

MICHIGAN

Post Number: 1845
Registered: Dec-03
Hey nice link jan!! lol
 

Bronze Member
Username: Varney

BirminghamEngland, UK

Post Number: 57
Registered: Sep-04
Well, Steve -

If it's any help to you (and I state now I am not an expert in audio, such as the likes of J. And Kegger) I tried this myself and here's what I thought of it.

I took just the two amps. One - a Cambridge Audio A5 and a NAD 3225PE. The former being brand new, the latter with a few years 'wear' on it. Not that it was 'worn' out or anything, just not as modern.

There is a slight power difference in these two amps. This should not pose a problem - but certainly works best in an 'amp per driver pair' (freq.) set up as, ideally, you want both channels to as loud as each other. Stereo seperation: good and wow! The detail was amazing on many tracks I listened to. Lacked Oomph in the bass though. I later learned this 'detail' might be due to the amp doing the treble job outshining the one doing the bass thing.

Then I tried it differently. This time with two NADs of (very nearly) the same power output. This time, I had one per channel. Great sound! Just like having a louder system (or was it?).

Conclusion?

Every one of these amps does it's job best on it's todd! This I have proved by repeated and analytical listening.

Yes, it's great to strap junk together 'to make a monster'! I love that side of things. You have the advantage, perhaps that these things cost you very little and maybe they are just that little bit expendable. Hey - you won't know until you try it - but I suspect I know WHY you sought advice in the first place and WHY you wouldn't try it until you'd checked first:

....YOU ARE SCARED YOU'LL BLOW SOMETHING UP! 'Course you are - and who can blame you...? - I certainly was.

Nothing wrong with experimentation - but heed this: the impedance issue is important. The whole problem with what I did was down to impedance - and of that I am sure. Check it, double check it and don't risk a good amp or a speaker-pair doing anything like this. You may regret it.

Other than that - have fun! If it sounds bad, it sounds bad. At least you tried and at least you know for sure whether it gets the desired sound you want or not.

There is a lot of sense spoken in this forum, btw - and much of it preceeds my post. I'd heed it, if I were you. However, I'll end up by saying: Who knows what the outcome might have been, but for the impedance mismatch? I might even have kept the configuration on.

Oh and cabling between these amps must be good. Skimp - and you are defeating a lot of things (but THAT is an entirely different debate - ain't it, J...?! :-)).

Regards,

V

 

J. Vigne
Unregistered guest


A very different debate, Varney. And Steve should read your post with the knowledge that it is possible to use one amp (strapped into mono or not) on a section of his speakers. Using the existing X-over, if it allows true bi amping, he can put one amp on the bass, and tweeter. Or by using an external X-over, he can do the same hook up. But external X-overs are kind of pricey. What it comes down to here is he can't really do this on the cheap. And that, as I read his question, seemed to be the heart of what he was trying to accomplish. Bi amped and tri amped systems are down the road for most listeners and should be the alternative after a system has reached its peak potential. It sounds as if a simple component upgrade would be the most effective route for Steve to go right now. Several cheap amps working at the same time still gives cheap sound. One good amp working by itself will give good sound.




 

Bronze Member
Username: Varney

BirminghamEngland, UK

Post Number: 58
Registered: Sep-04
You're damn right there, J.

Bi-amping on the cheap does seem like a bad idea. The three amps I had a choice to use in a Bi-setup really are nice amps, if taken on face value and, taking into account the value for money they represent. Each one performs well on it's own - which is why it made sense to see what kind of net result they could produce together. Two bad amps could, potentially, produce a 'doubly bad' sound, as you suggest. In fact, I wouldn't be surprised at all, if it were possible to create a 'terrible' sound, using a grouped set of reasonably good amps, if they were badly matched to each other - but that is just my own speculation.

I think the point of the excercise - and that which he needs to be aware of - is the fact Steve might learn something new about audio by experimenting a little. He might even produce something that, although far from hi-end, might shape a particular sound, which would be to his liking, pro-tem, before a potential upgrade is financially possible.

Of course, a job to be undertaken when there's nothing better to do.... But fun, nonetheless.

Regards,

V
 

New member
Username: Livewire3

Post Number: 2
Registered: Nov-04
does anyone know if the spl z1x3000d is any good?
 

J. Vigne
Unregistered guest


It Blows. What the heck is a splz1x30000d? And, isn't there a Mk II version already?









And what the heck made you ask it in this thread?







 

New member
Username: Livewire3

Post Number: 3
Registered: Nov-04
J.VIGNE WHAT DO YOU RECOMMEND?
 

J. Vigne
Unregistered guest


I guess I recommend you let me know what you are asking about. I have no idea from a simple model number what you want to know. And it appears no one else on this thread does either. Probably since I don't know what it is, I more than likely can't answer your question. Is it a car system? Because this is Home Audio that you had to click on to get here.

And you don't have to shout.




 

Anonymous
 
Now I can't believe you don't know the finer features of the spl z1x3000d!

My wife uses one all the time. It replaced our old z1x2000a, which offered us years of excellent service.

It comes with plenty of attachments (for getting into the corners). The 'turbo' button on the new d-series works wonders - but use with caution.... the bag gets very full, due to it's high suction abilities - we very nearly sucked up the cat when trying it out!

Yes, you DO have to shout, as the motor is VERY LOUD!
 

Unregistered guest
Hi i want to learn how to build simple amp for a less money. soundzz funny but i really need some help plzzz.

thanks
 

Unregistered guest
Hi I need help in building simple but powerful amp. plzzz help me out. I have no knowledge in electronics.

soundzz funney
 

J. Vigne
Unregistered guest

Put "DIY amplifier" into a search engine.

 

Bronze Member
Username: Varney

BirminghamEngland, UK

Post Number: 98
Registered: Sep-04
Hmm....

I did just that, actually and came across the AKSA by Aspen Amplifiers and found myself almost tempted, but for the time it would take to build.

http://www.printedelectronics.com/welcome.htm

Any experience with these DIY kits, J? Anyone? If so, be interested to know what you make of them.

V
 

J. Vigne
Unregistered guest

Kit manufacturers are interested in the success of their products even more than some manufacturer of complete systems who enjoy a repair facility to right their faults. Most kits are laid out with the level of difficulty assigned by the designer. The buyer simply decides what level their skills fit. The hardest task is often knowing how to solder properly. A task as simple as melting butter will often not result in ghee. It is this failure to solder properly that obstructs most kit buyers and results in the frustration level that a kit assembler can experience. Learn to sloder properly (there are sites on the internet to help), and the kit building process is usually rather simple. Another suggestion would be to begin by assembling a small tube amplifier since tube amps generally have simpler circuits than solid state.


 

Bronze Member
Username: Varney

BirminghamEngland, UK

Post Number: 100
Registered: Sep-04
Hmm, no.... I can't solder very well. I do work with my hands pretty well, so it's really only a matter of practice. I just never really had the need to solder anything before.

Actually, I like the idea of starting with tubes. It would be more fun to build something than just save up and buy it. I have a workspace to use when I can find the time. I wonder if I could find a very cheap kit to start with and move on up to higher end after learning on it.

Speaker cabinets would be easy to build, it's the actual requirements for them I'd have to learn first; volume to cone size, best jointing method, materials etc.

Maybe will take a look at the options in the new year.

V

 

J. Vigne
Unregistered guest

http://www.bottlehead.com/

 

J. Vigne
Unregistered guest

http://www.bottlehead.com/

 

Gold Member
Username: Kegger

MICHIGAN

Post Number: 1991
Registered: Dec-03
man you really like that stuff!

how much does a bottle of head cost?
 

Silver Member
Username: Varney

BirminghamEngland, UK

Post Number: 101
Registered: Sep-04
Fantastic. Worth a look over, the bottlehead site. I didn't make the gig, btw. Headache.

How do you find the tubes work with digital sources? They are traditionally used with analogue sources, so I wonder how they are with it?

I read in the instructions of an amp I bought NEVER to feed a digital source through an analogue tuner input. I don't understand this really. I presume my cable TV box (since I'm using digital TV) is a digital source? On a much older amp I own, I feed this into the tuner input. Doesn't seem to be any different to the CD input.

I think this qualifies as a 'stupid newbie question'. Any ideas?

V
 

J. Vigne
Unregistered guest

A raw digital output that might come from a digital out jack on a CD or DVD player will give a nasty sound, which could do damage to equipment, when attached to an analog input. By using the DAC in the source you are feeding an analog signal into your amp.

If the tube amp you choose is designed well you should have no problem running digital based sources through the amplifier. My feeling has always been a tube amp should reproduce what it is fed with as little change as possible. If the source is nasty, looking to tubes to remove the solid state crud is, in my opinion, a bad choice. As any amplifier will introduce some sound of its own, tubes will make listening to bad soild state or digital sources easier to take but shouldn't be used as a BandAid.


 

Silver Member
Username: Varney

BirminghamEngland, UK

Post Number: 102
Registered: Sep-04
Excellent. Thankyou.

V
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