A Few Random Noob Questions..

[lionfang]

1. On subwoofer amps, is low level or high-level input preferable? & Does either low level or high level input degrade audio quality?

2. Low level is un-amplified signal directly from the DAC, where high level is already amplified from the DAC, right?

3. From my (limited) understanding, higher resistance speakers are easier on amplifiers because there is less current on return. If this is the case, why not just add on a XYZ Mega Ohm Resistor after the speakers? Honestly i know nothing about electricity, but the speakers would still get their power right?

4. Does anyone know the position on the Dayton Audio DTA-100a for 30W? (so as not to exceed .01 THD)


Thanks guys! Sorry about the nooby questions

[Sydney]

1. On subwoofer amps, is low level or high-level input preferable? & Does either low level or high level input degrade audio quality?

2. Low level is un-amplified signal directly from the DAC, where high level is already amplified from the DAC, right?

3. From my (limited) understanding, higher resistance speakers are easier on amplifiers because there is less current on return. If this is the case, why not just add on a XYZ Mega Ohm Resistor after the speakers? Honestly i know nothing about electricity, but the speakers would still get their power right?

4. Does anyone know the position on the Dayton Audio DTA-100a for 30W? (so as not to exceed .01 THD)


Thanks guys! Sorry about the nooby questions

A low ( or line level ) input is easier to implement - a high level input is usually there for the attachment to devices ( amps/receivers ) that don't have a dedicated sub output.

higher resistance speakers

More correctly it is impedance ( think - impedes the flow of current ).
A resistor can be used to attenuate ( in ohms not Mohms ); A resistor burns off power in the form of waste heat.

[fastbike1]

There is no "position" on the DTA-100a. Sub amp are unique in being able to take an output from another amp (i.e. high level).

The DTA-100a is effectively an integrated amp the requires a source (CD / ipod, etc). As typical with these types of amps, the manufacturer plays with the ratings to give the impression of offering more than the competition. However you don't need to worry about "setting" things to stay below some distortion limit. It's already built in and called the volume control.
FWIW it's unlikely you can hear distortion below 10% and definitely not below 1%.

1. On subwoofer amps, is low level or high-level input preferable? & Does either low level or high level input degrade audio quality?

2. Low level is un-amplified signal directly from the DAC, where high level is already amplified from the DAC, right?

3. From my (limited) understanding, higher resistance speakers are easier on amplifiers because there is less current on return. If this is the case, why not just add on a XYZ Mega Ohm Resistor after the speakers? Honestly i know nothing about electricity, but the speakers would still get their power right?

4. Does anyone know the position on the Dayton Audio DTA-100a for 30W? (so as not to exceed .01 THD)


Thanks guys! Sorry about the nooby questions

[lionfang]

There is no "position" on the DTA-100a. Sub amp are unique in being able to take an output from another amp (i.e. high level).

The DTA-100a is effectively an integrated amp the requires a source (CD / ipod, etc). As typical with these types of amps, the manufacturer plays with the ratings to give the impression of offering more than the competition. However you don't need to worry about "setting" things to stay below some distortion limit. It's already built in and called the volume control.
FWIW it's unlikely you can hear distortion below 10% and definitely not below 1%.

What i meant is at what position does the volume knob exceed 1% THD

[duanebro]

The distortion will vary. There is no one level. Think of an amp as a voltage multiplier. The more voltage that comes in the more that goes out. So if you have 1v in from your source ( say a cd player) and the amp puts 10v out. Then if your ipod only puts out .5v then your amp will only output 5v. So the volume control will cut the output if your cd player is too loud. Ok so far? Now the amp can only "make" a certain amount of volts, after that the distortion rises quickly. So if you use your ipod you will need the volume set higher to get the same output as a cd player or other nonportable device. This is why no one can tell you what the limit on your volume knob is. To make things worse different recordings have different levels, so one song could clip and another not at the same volume level.

I just made up the voltage numbers to give you an idea btw. I don't know how many volts the amp can output.

[duanebro]

Speakers use a certain amount of electricity. Putting a resistor in series will split the voltage between the speaker and resistor. So you will just burn of some of the current on the resistor. Or you could say they would share the current. So the speaker would see less - but the amp would put out the same voltage.

Now if you have a speaker with a lower impedance it will draw more current at the same voltage as a higher impedance speaker would. So you can get more power out of a amp with a lower impedance speaker. (Note: half the impedance equals twice the power) So this is harder on a amp because it is doing more work. Looking at the ratings for amps you will see that they have more power at a lower load (impedance). There is much more to it than this if you want to learn.

[duanebro]

Speakers use a certain amount of electricity. Putting a resistor in series will split the voltage between the speaker and resistor. So you will just burn of some of the current on the resistor. Or you could say they would share the current. So the speaker would see less - but the amp would put out the same voltage.

[johnastockman]

1. On subwoofer amps, is low level or high-level input preferable? & Does either low level or high level input degrade audio quality?

2. Low level is un-amplified signal directly from the DAC, where high level is already amplified from the DAC, right?

3. From my (limited) understanding, higher resistance speakers are easier on amplifiers because there is less current on return. If this is the case, why not just add on a XYZ Mega Ohm Resistor after the speakers? Honestly i know nothing about electricity, but the speakers would still get their power right?

4. Does anyone know the position on the Dayton Audio DTA-100a for 30W? (so as not to exceed .01 THD)


Thanks guys! Sorry about the nooby questions

I can answer the first ?, as I've had experience going from a passive XO sub to adding a plate amp in the same sub; and going from the high-level speaker inputs/ouputs to the low-level input on the sub amp. I noticed a definite improvement in the SQ going to the low-level input from the speaker-level input. It's hard to describe without using the familiar subjective terms that describe SQ and it's attributes, but I found more resolution overall, especially from the satellite/main speakers and better definition from the lower frequencies.


John A.

[Whitneyville1]

John, I still want a Mike Hailwood Edition 920 Desmo tower drive Ducati ('68 as I remember) in Lucky Strike colors. With a 33" inseam and it's 36.5" seat height, we had small adventures at stop lights, but THAT was a motorcycle! You could lean it over on those Perrelli Gordons and the first thing to drag was your elbow or knee.
I have a "new" toy. A 1994 home-market Suzuki GSV500Z street-legal Formula-One two-stroke V-4. I got it thru Canada with 1200Km on it and the original owner scared himself to death on it. There isn't a piece of it a magnet will stick to. 363 lbs. gassed.

[fastbike1]

1978. The replicas were 900SS (864cc) bikes w/ different plastic. Colors were red,white, and green. The team made the colors up from a Castrol can, which was Hailwood's sponsor.

The stock 900SS in 79 were black/gold, similar to Lucky Strike colors but not any replica. Seat height wasn't that tall either. You don't have to make this stuff up.

John, I still want a Mike Hailwood Edition 920 Desmo tower drive Ducati ('68 as I remember) in Lucky Strike colors. With a 33" inseam and it's 36.5" seat height, we had small adventures at stop lights, but THAT was a motorcycle! You could lean it over on those Perrelli Gordons and the first thing to drag was your elbow or knee.
I have a "new" toy. A 1994 home-market Suzuki GSV500Z street-legal Formula-One two-stroke V-4. I got it thru Canada with 1200Km on it and the original owner scared himself to death on it. There isn't a piece of it a magnet will stick to. 363 lbs. gassed.

[johnastockman]

John, I still want a Mike Hailwood Edition 920 Desmo tower drive Ducati ('68 as I remember) in Lucky Strike colors. With a 33" inseam and it's 36.5" seat height, we had small adventures at stop lights, but THAT was a motorcycle! You could lean it over on those Perrelli Gordons and the first thing to drag was your elbow or knee.
I have a "new" toy. A 1994 home-market Suzuki GSV500Z street-legal Formula-One two-stroke V-4. I got it thru Canada with 1200Km on it and the original owner scared himself to death on it. There isn't a piece of it a magnet will stick to. 363 lbs. gassed.

Fastbike is correct. Holy sh!t, a GSV500 2-stroke? I'm speechless...well, not quite. I only saw one of those in person. I used to take a 2-week ride every year when I was still riding, up into BC, Alberta and Saskatchawan (sp). I had friends that lived in Westlock, Alberta. Even doing that for 20 years, I never ran out of great back roads, nice people and amazing scenery. I met a guy riding a GSV in Penticton, BC at a small diner. I spent so much time oogling the bike before I went in, that he came out and asked me if I was familiar with the model. Great memory, wish I'd taken some pics of it. Cherish that bike. It deserves to be ridden and loved. If you would be so kind as to send me some photos to my e-mail address, I'd be extremely grateful. Mike Hailwood was one of my heros, as is John Surtees, Gary Nixon, Kenny Roberts, Cal Rayborn and my many maternal relatives that were racers for the major manufacturers since the days of boardtrack racing. My grandfathers older brother was the original Wrecking Crew member with Indian, then going on to ride for Harley and Excelsior before the demise of boardtrack racing. Ok, I've used up my OT posting privileges...I told Dirk I wouldn't mention motorcycles again since I got vilified for my strong feelings about them.


John A.

[Whitneyville1]

I got new expansion chambers made for it in CA by the same guy that made them for Team Suzuki. I'm waiting on DOT legal tires from Metzler to arrive.I had a new advance chip "burned" in CA too. It's a tiny bike. We'll see if it'll keep up with my Hiway Patrol buddy's '94 Haybusa (with mods). We're gonna try and break the record from Tulsa to OKC on the Turnpike (103 miles from toll-booth to toll-booth) currently of 47 minutes, 50 seconds held by a Yamaha XZ1300. We think we can take 12-13 minutes off that. Rocket 135 octane yellow fuel, in my case, Bel-Ray 100% silicone pre-mix @1:120, 2 liters of Bel-Ray turbine 20 in the crankcase.

[johnastockman]

I got new expansion chambers made for it in CA by the same guy that made them for Team Suzuki. I'm waiting on DOT legal tires from Metzler to arrive.I had a new advance chip "burned" in CA too. It's a tiny bike. We'll see if it'll keep up with my Hiway Patrol buddy's '94 Haybusa (with mods). We're gonna try and break the record from Tulsa to OKC on the Turnpike (103 miles from toll-booth to toll-booth) currently of 47 minutes, 50 seconds held by a Yamaha XZ1300. We think we can take 12-13 minutes off that. Rocket 135 octane yellow fuel, in my case, Bel-Ray 100% silicone pre-mix @1:120, 2 liters of Bel-Ray turbine 20 in the crankcase.

I can smell the exhaust now. I remember it well. There was a few guys I used to club race with here in the NW, at the old SIR and PIR tracks that raced the RD350's and RD400's, along with the Kawi and Suzuki triples. Seattle International is now Pacific Raceways, and Portland International is still around. I started in the clubs WMRRA and OMRRA, the local amateur sanctioning organization, back in '85. I found a Yamaha SR500 single that I cafe'd with the usual handlebars, rear-sets, carb mods, slip-on exhaust, stainless steel front brake line and the required safety wiring. I was the only disabled guy out there. I never crashed and almost always finished in the top ten in my class. I did that until about 2000, when I got a touring bike and started putting on the miles. I did a lot of the Saddlesore events locally. Have fun, that's a terrific bike.


John A.