Home stereo class a/b amplifiers?!

[csheffield]

Hello everyone. Im trying to piece together a mid level home stereo system. I wanted to start with a pair of Seas Idunnes Speakers (80W RMS @8ohm 2 way) powered by a class a/b amplifier. I cant find a single home use amp for sale through google that says what class it is unless it's class D. I have however found many automotive amplifiers that claim class a/b. Am i stuck using a automotive amp for my plan? Does anyone know where to find class a/b home amps? Ive been at it for hours now.

[wkhanna]

THIS link may help

the vast majority of solid state, home-audio stereo amplifiers are class A/B

class A are typically tube amps...they are V inefficient from an efficiency standpoint since they run at full power at all times, whether producing an audio signal or not.
and, tubes wear out.

class A/B amps are more efficient running at full power only when producing the first few watts of power.

class D are the most efficient, but V good sounding ones are still a bit pricey despite the maturing technology.

tell us more about the type of audio system you want, why, & what the room environment is (e.g., size, material construction, furnishings, etc.) & your budget.

we can start pointing you in practical directions from there.

[csheffield]

Well my father has a 2 car garage I would love to build a nice stereo setup for him for a late christmas present. Its probably something along the lines of 20' x 15'. It contains what any well used garage does. Tools, table saws etc. He will mostly be listening to rock (70s thru present). I thought the the idunnes 2 way kit seemed like a good entry point for a quality setup. I was thinking of a class a/b 2.1 channel amp just incase the reviews on the idunnes were true and the bass left something to be desired for. He could always add a sub later on in the future. I wanted to find a decent standalone DAC as well so he can play some of his high quality albums he has and continues to download.

I was hoping to keep the budget under 900 dollars not including the speaker box construction. I am going to make him buy and build the boxes since he is good at cabinetry and enjoys it.

[wkhanna]

could you explain to me what an "idunnes 2 way kit" is, please.
i am not familiar with this....

will this system be running from a computer?
your father will be making the speakers?
if so, what speakers.........will you be using a design from our forum? (not that you need to, it just gives a better reference point for equipment suggestions)

[csheffield]

i misspelled it firstly. Seas idunn is a speaker kit from the Seas company . It comes with a suggestion from Seas on what to use as a tweeter, woofer and a crossover schematic. It crosses over at 2600 khz. The woofer is an 80 watt rms 250 max 89 db sensitivity driver and the tweeter is a 55 watt rms 150 watt max driver. I said my dad makes cabinets not speakers. Seas provides a few suggested speaker box plans that are appropriate to the design.

These speakers will be running as follows......a smartphone or computer ->DAC ->home style amp -> 2x 2way Speakers.

Now knowing that most home amps are in fact class a/b I am just trying to determine how many watts to use. I got a sound meter app for my smart phone to try and figure out the max volume my dad likes to listen at but it doesnt seem to work despite the good reviews.

What db level does everyone here find as an appropriate max without being the annoying guy in the neighborhood?

[csheffield]

PS http://www.seas.no/index.php?option=...=66&Itemid=365

[Renron]

Csheffield,
So you want to get your Dad addicted to building speakers huh?
It's a slippery slope that only goes downhill. LOL. Welcome to the Forum.
Have you purchased any drivers yet? Is your heart set on this speaker? It looks rather soft in the bass section, and sensitivity is kinda low too. IMO.
Have you seen the plans for Jon's Natalie P speakers? (can be built smaller) or perhaps Mark Ks MT? or Modula or Modula MTM? Statements (big speakers)
Have a look here for some ideas.

http://www.htguide.com/forum/showthread.php?28655-A-Guide-to-HTguide-com-Completed-Speaker-Designs

Lots of great speaker from which to choose.
I hope I helped and didn't make it worse for you.
Ron

[csheffield]

Thanks for the reply and links! I dont understand why you say the sensitivity is low. The woofers for the idunn are 89db and the Modula MTM design also uses woofers of the same sensitivity.

Unfortunately looking at charts does me no good. It would be nice if I knew an audiophile who can sit me down and show me what they mean in correlation to sound with some of their own setups. Anyways I was basing quality off of price. The woofers in the modula mtm are half the price of the seas but uses two which makes it around the same price of build as the idunn I was looking at which is nice.

So when you do a MTM build, does the RMS wattage of the two woofer drivers add, average or use the lowest rms value of the two? I am still really confused about what amplifier to use to drive a loud speaker setup. The modula mtm uses two 60 watt rms woofers. Does that mean 60 watts max continuous for the channel or does it mean 120 watts continuous? If its 60 watts max I found a decent little 2 channel from sony that runs 50 watts per channel which was priced alright.

[Renron]

Csh,
I'll try to answer your questions in order, excuse me if it doesn't come out that way. Several items are intertwined.
Ripped straight from the Madisound website,
"As seen in the figure the average sensitivity is 85dB " That's why I said sensitivity is low (ish)
Sensitivity is "normally" measured @ 2.83V - 1 meter from midpoint of the drivers. This is the measurement to determine how loudly a speaker will play at a specific volume. It is NOT a measurement of maximum dB a speaker can play.

With an MTM speaker design the two woofers add +3dB.
This was copied from AVSforum, the author was Fbov.
"MTMs are the simple example.
- two 8-Ohm drivers in parallel are 4 Ohm load, draw twice the power (+3dB) and have twice the area (+3dB) so the total voltage sensitivity is +6dB.
- two 4-ohm drivers in series are an 8 Ohm load, draws half the power (-3dB) and still have twice the area (+3dB), so there is no change (0dB) in total voltage sensitivity.
In the 4-driver case, I assume series/parallel wiring to achieve a 4 Ohm load. Two 4-Ohm drivers in parallel are a 2 Ohm load, and a +6dB sensitivity. Two of the 2-ohm loads in series are back to 4 Ohms, but as we saw above, with no net add in sensitivity.
Example of 8-ohm drivers in parallel: Aviatrix
Example of 4-Ohm drivers in series: TriTrix

Higher price does not equate to better sound. The Overnight Sensation MTM is UBER cheap but sounds terrific, way better than they have any right to for the $$$. Bravo to Paul Carmody for his many inexpensive designs (his forte) The Swope is an extreme value.
Jon Marsh is know for his great sounding speaker designs, at a higher initial pricetag. Don't forget you need crossovers with the speakers, prices for XO components can range from 1/4 to 1/2 or more of the speakers final cost. Quality components make a difference, but you don't have to go crazy either. Duelund comes to mind. got a money tree?

If you look at the RMS wattage of a speaker only, then you are building a P.A. system. (public address)
MOST of the listening is done within the first 10 watts of the amplifier. The higher the sensitivity, the less wattage needed to play at the desired dBs. To increase the dB +3 you have to double the power.
Class A / or A/B Amplifier wise, it is a jungle of techno babble by the manufacturers designed to confuse you into thinking that higher wattage is better. Not necessarily so. More importantly, the Ohms rating on amplifiers will tell you the basic quality of the unit. Basic rule of thumb is weight. The heavier , the better. This excludes class T & Class D amps which are in a class by themselves and not subject to the weight issue. Forget about Amps designed for the automobile industry. Wrong direction.

If your system starts with really high quality speakers, later changes to upstream equipment can be evaluated easier.

There are a LOT of great speaker designs available to the DIYer, take your time and find the one that fits your preferences best.
If you ask about specific speakers we can help or guide you better. Start with how much you want to spend on speakers, work on the other parts later. You hear the music through the speakers!

Here is a very good page to read with lots of examples. Please read this, it will explain better than I can.

https://www.lifewire.com/loudness-and-amp-power-3135081

Merry Christmas,
Ron