• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

First halfway serious hifi; couple of questions on setting it up ...

Joined
Mar 6, 2020
Messages
7
Likes
12
#1
Got my first halfway serious (used) hifi system used last week. It's pretty old; nothing like you guys would pay attention to but pretty decent and it does sound good. The system consists of a/d/s L310 speakers, an SVS SB1000 sealed subwoofer, a Dared SL-2000A linestage/preamp, and a NAD 906 power amp. Lurking this forum, I added a slightly used Topping D50S DAC because it got a good review and seemed like a lot of bang for the buck; it came with the matching linear power supply which seems totally unnecessary according to this site but anyway it's there. So far I have set it up to stream Apple Music/iTunes from an Apple TV 3rd-generation, connected into the DAC by a Toslink cable. Seems to work fine -- farrrr better than anything I have ever had but I just had pretty low-end systems -- but I am wondering about a few things:

1. First of all, what's the point of a tube preamp? I also play guitar and the reason almost all serious players use tube amps is to intentionally _get_ distortion, not minimize it. Its looks awesome but I assume it's probably more show than go.

2. The NAD power amp is kind of cool. There are 6 channels, which can be bridged to 3. I only need two. The manual says it can be set up for bridging. Should I do this? I can't imagine those little speakers need all that much grunt but if it's a better way to go, I will do it. Also, the rear of the amp has tiny knobs that allow you to set the output volume ... what should they be set at?

3. I'm confused at how to set up the subwoofer. The system doesn't have any special sub-out LTE connection, so I have just connected it with regular RCA cables to the Line Out jacks on the power amp. What do I set the crossover at? Even more confusing is, how do I set the "Phase" knob? ... I can't hear any difference whereever it's turned to.

4. Is it really so bad to just put the speakers in a bookcase? Unless it really hurts someone's feelings, I would like to put them on a high bookshelf and put the subwoofer in an old unused fireplace down below them. Will this really mess up the sound?


Many thanks if one of the hotrodders here can offer a couple of heads-ups!
 

raindance

Active Member
Joined
Sep 25, 2019
Messages
181
Likes
126
#2
That preamp probably has way more gain than you need and will be noisy. Dared products aren't very well built or reliable, FYI. Be careful with turn on sequence! Preamp first, wait a few minutes, then power amp. Reverse this sequence when turning off. If you don't do this, you'll fry something.

The output impedance of that preamp is quite high and capacitor coupled, so you would be better off feeding the speaker outs from the power amp to the sub to avoid substantial bass loss. You will probably get some hum for free.
 
OP
F
Joined
Mar 6, 2020
Messages
7
Likes
12
Thread Starter #3
That preamp probably has way more gain than you need and will be noisy. Dared products aren't very well built or reliable, FYI. Be careful with turn on sequence! Preamp first, wait a few minutes, then power amp. Reverse this sequence when turning off. If you don't do this, you'll fry something.

The output impedance of that preamp is quite high and capacitor coupled, so you would be better off feeding the speaker outs from the power amp to the sub to avoid substantial bass loss. You will probably get some hum for free.

Okay great thanks very much ... I'll hook the sub up to the power amp then instead of the preamp output jacks.

Question: is it normal for the small tubes to flash pretty brightly when the system is turned on?

This is great, I knew this would be the right place to ask!

PS: it does have a lot of gain. Unfortunately I need something in there to boost the signal; running the little DAC output straight into the power amp doesn't provide much system volume at all. Maybe at some point I can purchase a better-quality linestage unit if it's really true that Dareds suck. Still sounds 1000x better than what I used to have though!
 

raindance

Active Member
Joined
Sep 25, 2019
Messages
181
Likes
126
#4
Check your mains voltage. Chinese preamps are designed for 110/220 volts. My house measures 127 volts sometimes. I suggest an APC regulator to drop it down closer to 110.

If the tubes are European, the heater flash is normal.
 

andreasmaaan

Major Contributor
Forum Donor
Joined
Jun 19, 2018
Messages
4,418
Likes
4,261
#5
1. First of all, what's the point of a tube preamp? I also play guitar and the reason almost all serious players use tube amps is to intentionally _get_ distortion, not minimize it. Its looks awesome but I assume it's probably more show than go.
You're correct IMHO: all else equal, tubes are less linear than transistors, although ofc it varies from amp to amp.

2. The NAD power amp is kind of cool. There are 6 channels, which can be bridged to 3. I only need two. The manual says it can be set up for bridging. Should I do this? I can't imagine those little speakers need all that much grunt but if it's a better way to go, I will do it. Also, the rear of the amp has tiny knobs that allow you to set the output volume ... what should they be set at?
Perhaps counterintuitively, smaller speakers tend to require more power to reach a given SPL (a smaller woofer in a smaller box will tend to be less efficient than a larger woofer in a larger box).

However, according to the specs I was able to find online, your speakers are only rated to handle 10 watts, which is less than the NAD's 30 watts in single-ended mode. In these circumstances, there's unlikely to be any advantage in bridging the amp.

3. I'm confused at how to set up the subwoofer. The system doesn't have any special sub-out LTE connection, so I have just connected it with regular RCA cables to the Line Out jacks on the power amp. What do I set the crossover at? Even more confusing is, how do I set the "Phase" knob? ... I can't hear any difference whereever it's turned to.
The way you've connected it is correct. The low-pass filter should be set on the subwoofer itself. You are necessarily running your mains fullrange here (there is no way to high-pass filter the signal to them with your current setup). Therefore, you have two basic options:
  • determine the cut-off frequency of your mains by measurement, then set your subwoofer crossover at the same frequency
  • cross over your sub quite high so that there is a significant overlap between the mains and the sub
Which will work better is going to depend on all sorts of variables that you'll only be able to guess at without taking measurements. I would suggest trying the second approach first, especially if your sub is located close to the speakers.

Regarding the phase knob, again it's of limited usefulness without having taken measurements. And if you can't hear any difference regardless what position it is in, leave it at zero. Be sure though to have someone else adjust it while you sit at the listening position, before you decide for sure that you can't hear any difference (it will be easier to hear any difference from the listening position than from right next to the sub).

4. Is it really so bad to just put the speakers in a bookcase? Unless it really hurts someone's feelings, I would like to put them on a high bookshelf and put the subwoofer in an old unused fireplace down below them. Will this really mess up the sound?
If it sounds good to you, then that's fine. Ideally, the speakers would be 1 metre or more from any walls, but this is not always practical. If you are going to place the speakers in a bookshelf, it would be best to try to get them at ear height. They will also tend to sound better in a bookshelf that's full of books etc than in an empty one, and placed so that books and other stuff in the shelf are more or less flush with the front of the speaker's baffle.

For example, the setup below would likely sound better if there were also records surrounding the speakers:

 
Last edited:

andreasmaaan

Major Contributor
Forum Donor
Joined
Jun 19, 2018
Messages
4,418
Likes
4,261
#8
Unfortunately I need something in there to boost the signal; running the little DAC output straight into the power amp doesn't provide much system volume at all.
I'm quite surprised by this. Your Topping should be capable of 2V RMS output, while your NAD's inut sensitivity is specced at 1V for full rated power into 8 Ohm. If your D50 is unable to drive the amp to acceptable levels, something would seem amiss to me.
 
OP
F
Joined
Mar 6, 2020
Messages
7
Likes
12
Thread Starter #9
I'm quite surprised by this. Your Topping should be capable of 2V RMS output, while your NAD's inut sensitivity is specced at 1V for full rated power into 8 Ohm. If your D50 is unable to drive the amp to acceptable levels, something would seem amiss to me.

Thanks very much for your reply. Turns out you're right!!! I didn't see them before, but on further examination there are these tiny level knobs on the back of the power amp and when I cranked them up the DAC can drive the system plenty, plenty loud!

I can't say the system sounds much different without the tube preamp thing. Maybe just a tiny bit brighter. But every bit as good. So I wonder what the preamp was intended to do? Department of redundancy department!!!! I am ditching the middleman here -- the thing adds exactly zero value!!!
 

andreasmaaan

Major Contributor
Forum Donor
Joined
Jun 19, 2018
Messages
4,418
Likes
4,261
#10
Thanks very much for your reply. Turns out you're right!!! I didn't see them before, but on further examination there are these tiny level knobs on the back of the power amp and when I cranked them up the DAC can drive the system plenty, plenty loud!

I can't say the system sounds much different without the tube preamp thing. Maybe just a tiny bit brighter. But every bit as good. So I wonder what the preamp was intended to do? Department of redundancy department!!!! I am ditching the middleman here -- the thing adds exactly zero value!!!
Very happy to hear this :) Enjoy.
 

Mnyb

Active Member
Joined
Aug 14, 2019
Messages
232
Likes
250
Location
Sweden, Västerås
#12
Thanks very much for your reply. Turns out you're right!!! I didn't see them before, but on further examination there are these tiny level knobs on the back of the power amp and when I cranked them up the DAC can drive the system plenty, plenty loud!

I can't say the system sounds much different without the tube preamp thing. Maybe just a tiny bit brighter. But every bit as good. So I wonder what the preamp was intended to do? Department of redundancy department!!!! I am ditching the middleman here -- the thing adds exactly zero value!!!
That’s a good idea let the DAC drive the power amp directly , set the knobs on the NAD so that you can use a decent part of the volume range of the DAC .
If you want to optimise this a bit set the level knobs on the NAD so that full volume on the DAC is as loud as you ever wanna listen but not louder .
 
Top Bottom