Sub Advice for use with Topping TP20 and Pioneer BS22s

[Josh83]

This is my first post, though I've searched this forum and several others, reading several dozen threads on the topic of budget subs and T-amps.

Basically, I have little experience with powered subs. My main systems have either been a receiver with towers or a receiver with an old Cambridge Soundworks satellite/passive sub combination.

But I just purchased a Topping TP20MK2 and some Pioneer BS22s for a small home office system. I'm very pleased with this setup, but I'd like to add a powered sub to round out the sound a bit.

So, I have two questions:

1.) The TP20 does not have a sub out. So I'd be running speaker wire to the hi-level inputs on whatever sub I get. For subs with hi ins and hi outs, it's clear I'd run one set of wire to the sub hi ins, then wire from the sub hi outs to the BS22s. However, for subs without hi outs, I'd have to run two sets of wires from the TP20 -- one set to the sub, one set to the BS22s. Will either/both of these wirings cause any issues? It seems like lots of people use powered subs with T-amps wired parallel. However, I've read a few posts with people mentioning issues with the grounding of older T-amps and the sub. (Grounding stuff goes over my head.)

2.) For a budget sub, I've been debating between the Pioneer SW-8MK2 that matches the BS22s, the Martin Logan Dynamo 300, the Dayton Sub 800, the Dayton Sub 1000, and the BIC V1020. My room is small (10x12), I'm not really a bass-head (the BS22s are, frankly, just barely too little bass for me by themselves), and I'm only going to be listening to music (no movies or games), particularly classic rock and soul, so the musicality of the sub is my prime concern. I'd appreciate any recommendations among these subs or others in the $100-$150 range (which I know isn't a large budget at all).

Thanks, in advance, for any and all advice.

 

[rojo]

For that price range, a used local sub would probably be your best bet. Where do you live? I'll help you find something. If nothing better pops up locally, put this 12" 250w sub at the top of your list.

Regarding hookup, you could use rca piggyback cables at the Topping amp's input to split the preamp signal into a sub.

Edit: Oh, you said small, and for a small office. OK, how about a 6.5" sub with an f3 of 30Hz?

By the way, are you using a PC as the source into your Topping amp? You might be interested in some open-source room correction software.

 

[agarwalro]

1.) The TP20 does not have a sub out. So I'd be running speaker wire to the hi-level inputs on whatever sub I get. For subs with hi ins and hi outs, it's clear I'd run one set of wire to the sub hi ins, then wire from the sub hi outs to the BS22s.

This is the correct way to go about it.

However, for subs without hi outs, I'd have to run two sets of wires from the TP20 -- one set to the sub, one set to the BS22s. Will either/both of these wirings cause any issues? It seems like lots of people use powered subs with T-amps wired parallel. However, I've read a few posts with people mentioning issues with the grounding of older T-amps and the sub. (Grounding stuff goes over my head.)

This is not a good way to go about it.

2.) For a budget sub, I've been debating between the Pioneer SW-8MK2 that matches the BS22s, the Martin Logan Dynamo 300, the Dayton Sub 800, the Dayton Sub 1000, and the BIC V1020. My room is small (10x12), I'm not really a bass-head (the BS22s are, frankly, just barely too little bass for me by themselves), and I'm only going to be listening to music (no movies or games), particularly classic rock and soul, so the musicality of the sub is my prime concern. I'd appreciate any recommendations among these subs or others in the $100-$150 range (which I know isn't a large budget at all).

My pick would be the Dayton Sub 1000. Primarily, it has the Line Inputs. That opens up the a more preferred connection option. On your source device use Y splitters. Run one signal to the TP20 and one to the Sub 1000. Set level and cross over on the sub and you are done.

 

[Josh83]

Thank you both for your helpful replies.

It seems that running parallel wires from the TP20 to the bookshelf speakers and the sub is not recommended, then? Is that because of a fidelity issue, or a grounding issue? If so, why do so many subs have only hi ins and no hi outs? For subs with only hi ins, would running one set of speaker cable from the TP20 to the sub and another set from the sub ins to the bookshelf speakers work? I've read that's an alternative to running two sets of wires from the TP20. Or is that incorrect? I'm a little confused as to why wiring in parallel from the amp to the speakers and the sub hi ins is incorrect. (The Martin Logan 300 has hi ins and no hi outs, and its manual actually recommends running two sets of speaker wires from the L/R on the amp. The Steve Guttenberg CNet guide on wiring subs does, too.)

It seems like for the Dayton, since it has hi outs, too, I can go the TP20>Dayton hi ins>hi outs>BS22 route, correct? Is it a fairly musical sub?

You both mention an RCA splitter from the source, which is an iMac in this case. I've thought about doing that, but then I'd essentially need to leave the TP20 at a set volume and use the iMac's volume control. Overall, I think I'd prefer to be able to use the TP20s volume knob. But I'd be curious to know if there's a reason to prefer using the RCA line level input on a sub over a speaker wire hi level input? (I'd assumed the quality was the same.) Does splitting the iMac's output degrade the signal at all? If I were to go the RCA route, does the crossover on the sub still work? I thought the RCA route was for receivers that managed the crossover themselves and overrode the sub's internal crossover.

Once again, thanks for all the help.

 

[rojo]

I'd think running a pre-amp signal to the sub would yield a cleaner result than an amplified signal that the sub's plate amp has to attenuate and then amplify again. That's why I suggested the piggyback cables or splitters.

But you're right about not being able to control the sub volume with the Topping amp that way. Possible solution would be to add a Rolls SX45 2-way xover, which would let you control the volume of both at preamp, as well as give you the added benefit of a matched high pass filter for your Pioneers for a better blend. That Rolls + the 6.5" sub I recommended above, and you're still pretty close to your budget.

There are some subs that will set a high pass filter on the high-level outputs to match the crossover setting dial on the sub, but they're not very common. I know some of Hsu Research's subs do this, but I know of none close to your budget.

 

[j_garcia]

Just a word about Topping - I'm about to mail back my SECOND TP-60 in a row as it had a problem right out of the box. Love the amp, but really less than impressed with quality.

If musicality is your concern, your budget for a sub is too low and none of those are going to deliver excellent music IMHO. Of those listed, the sub1000 would probably be my choice, but I'd probably save and get a HSU STF-2 instead.

 

[agarwalro]

It seems that running parallel wires from the TP20 to the bookshelf speakers and the sub is not recommended, then? Is that because of a fidelity issue, or a grounding issue? If so, why do so many subs have only hi ins and no hi outs?

Optimally, all analog signal processing needs to be done at Line level and not Speaker Level. Subs have Speaker Level inputs since it makes for a flexible product with a broader customer base. A lot of subs have Speaker Level inputs since many amps can mirror input signal to A+B speaker configuration. So, many people can use A for main speakers and B for Sub. Not having Speaker Level outs on a sub is either because it is passive (no built in amp) or because the designer cut that feature for cost savings.

For subs with only hi ins, would running one set of speaker cable from the TP20 to the sub and another set from the sub ins to the bookshelf speakers work? I've read that's an alternative to running two sets of wires from the TP20. Or is that incorrect? (The Martin Logan 300 has hi ins and no hi outs, and its manual actually recommends either of the above wirings for amps without a sub out.)

No, this is iffy at best and may blow the TP20 at worst. Mainly, we don't know the power draw on the sub Speaker Level input. In effect it is like adding a second pair of speakers to the TP20.

It seems like for the Dayton, since it has hi outs, too, I can go the TP20>Dayton hi ins>hi outs>BS22 route, correct? Is it a fairly musical sub?

Yes you can take that wiring approach, but, using the Line inputs is highly preferred. I have never heard the sub and cannot comment on the quality. FWIW, the Parts Express and Amazon feedback is overwhelmingly positive. If you can stretch the budget slightly, the BIC F12 is my choice for a budget sub. I have set one of for somebody and for $195 delivered, I came away amazed.

You both mention an RCA splitter from the source, which is an iMac in this case. I've thought about doing that, but then I'd essentially need to leave the TP20 at a set volume and use the iMac's volume control. Overall, I think I'd prefer to be able to use the TP20s volume knob. But I'd be curious to know if there's a reason to prefer using the RCA line level input on a sub over a speaker wire hi level input? (I'd assumed the quality was the same.) Does splitting the iMac's output degrade the signal at all? If I were to go the RCA route, does the crossover on the sub still work? I thought the RCA route was for receivers that managed the crossover themselves and overrode the sub's internal crossover.

If you prefer to use the TP20 for volume control, you have no option but to go iMac > TP20 > Sub > Speakers.

If you truly want to get the best sounding setup, the TP20 needs to be replaced with something that does bass management. If your speakers and sub are at different distances, then also something that does distance setting. In short, a budget AV receiver.

 

[Josh83]

Does the hi level input of a powered sub actually draw any power from the amp (the Topping, in this case)? I've read several places that the impedance of hi level inputs on powered subs means that a powered sub's effective draw on an amp is zero. Is that incorrect?

 

[rojo]

Josh, I've read that, too. This cat seems to know what's up. Still, I agree with agarwalro that the high level inputs and outputs are offered on many subs as a way to sell more subs, but it's hardly the recommended method of connection when you can use RCA or balanced connections instead.

I still recommend the Rolls crossover + the 6.5" sub. In a 10x12 room, it's not going to take much to fill in your low end, and you did say your existing bookshelf speakers were *almost* enough bass. No reason to get a bigass home theater behemoth for classic rock and soul, then figure out which fifth of your small room you no longer need to walk in. The crossover will let you more easily blend the sub with your bookshelfs, letting you cross over higher to divert more bass to the sub for more chest punch. It'll allow you to turn up your Topping amp louder with less clipping, since bass signal is the hardest to drive. The crossover will also further prevent bass from reaching your tweets, so you'll get cleaner highs at higher volumes should you feel the need to rock out.

 

[slipperybidness]

Does the hi level input of a powered sub actually draw any power from the amp (the Topping, in this case)? I've read several places that the impedance of hi level inputs on powered subs means that a powered sub's effective draw on an amp is zero. Is that incorrect?

It certainly does draw some power from the amp, but I don't know how much. I would guess that it is pretty low power draw though.

It seems like you are looking for a good reason to go with the Hi-level inputs. I really don't think there is any good reason, other than possible simplicity.

You could get the stuff to try it both ways and then report back with your findings.

Edit:
I think the real problem was mentioned previously. Taking an amplified signal, attenuating it back to line level, then re-amplifying it for the sub is not ideal by any means and is a waste of energy.

However, that is also exactly how my subs are hooked up in my car.

 

[Josh83]

The main reason I'm trying to figure out whether hi level is a viable option definitely comes down to simplicity (a desire to keep the full range signal going to the BS22s and to be able to use the Topping's volume control). However, I definitely don't want to cause power and/or audio quality issues, so this discussion has definitely been helpful. I haven't completely ruled out going the RCA route, though I think the piggyback cables are more likely than the Rolls, given my budget (and desire to keep full signal going to the BS22s). Likewise, my reason for going with the Topping, rather than a full receiver, comes done to desk/shelf space in my office, as well as budget.

As far as a powered sub's hi level input's draw from an amp, is the difference between the Dayton (with hi outs) and subs with only hi ins that the Dayton sends some of its own power to the BS22s? Otherwise, wouldn't the hi outs just be the same as wiring from the Topping in parallel to a sub with only hi ins?

 

[rojo]

The impedance the Topping amp sees might be different if connecting parallel, rather than using the sub's high level outs as a passthrough. So a daisy chain of Mac -> amp -> sub -> speakers is recommended. If you feel like playing mad scientist and have a multimeter, I'd be interested to know whether this is actually the case.

But it's my understanding that most subs with a high level output simply pass through the signal untouched with no additional amplification or processing. Like I said earlier, some Hsu subs can apply a high pass filter on the high level outs. But the Dayton, Acoustic Audio, BIC, et. al. will simply pass through. Your Pioneers will play the same signal as before you had a sub.

 

[Josh83]

For that setup (Mac>amp>sub>speakers), does the sub need to have a hi out, or could I run one set of wires from amp to sub in and a second set from the sub in to the speakers (meaning the sub hi input is where two sets of wires would be in one set of posts/clips, not the amp)? That's actually the recommended wiring in the Martin Logan 300 manual, since it's a sub without hi outs.

I have no electrical knowledge, but if you tell me what to do with a multimeter in this circumstance, I'd be happy to do it! (Haha.)

 

[rojo]

Well, far be it from me to argue with the Martin Logan manual. I'll tell you what you can do with your multimeter. You can... set it to the 200 ohm setting and see what it reads when you touch the leads to the inputs of one of your bookshelfs. Then do the same thing with the sub connected, and see whether the value changes. If the change is less than an ohm difference, then there's probably nothing to worry about.

 

[Josh83]

I've got no objection if you want to disagree with a manual! (I haven't bought the ML, just read the manual online.)

I think my decision, if I want to stick with hi level inputs, comes down to whether I want to get a sub with ins and outs or risk getting one with ins only and doing a parallel wiring or the one mentioned above. (In which case, I might try the multimeter to see what it says. Thanks for the advice on that!)

 

[markw]

From what I can find, there is no way to use a line level sub with it unless one wants to tap the signal before it goes into the TP20 which would make it's volume control useless for controlling the sub.

At the frequencies that a powered sub handles. the amp sees a very high impedance so it puts virtually no additional strain on the amp to which it's attached. And, the sub's internal amp sends no power to the mains no matter where they are connected.

It would make no difference to the TP20 whether the mains are connected to the sub or in parallel to the sub at the amp's speaker outputs.

As to any hum problems with that mini amp. that's a design problem with the mini amp that cannot be remedied externally.

Finally, I can't see how a multimeter will be ablr to tell you anything useful here.

 

[Josh83]

Thanks for the continued advice. I think I'll go with a <$150 hi-level input sub, but I still haven't decided which one yet. I've got a cheap multimeter, so I'll see if there's any difference in the input to the BS22s, just out of curiosity, but it's good to know that there should be no difference.

FWIW, my Topping TP20MK2 has very little hum. Overall, it's actually got less than the old Technics and NAD amps I've had. It does have more hum than the Denon receiver I have in my main setup, but given that the Topping is 1/8 the price, I'm certainly not disappointed. Overall, the Topping sounds better than the Technics, as well as a cheap Lepai I tried out before getting the Topping.

 

[markw]

Mutimeters don't measure impedance. They measure DC resistance, a totally different and unrelated animal.

While impedance is stated in ohms, impedance is based on an AC signal and varies greatly depending on the frequency at which it's measured.

If you look at some measurement charts of speakers you'll be able to see this variance, and it ain't small.

 

[agarwalro]

This amp might be your ticket, Dayton Audio APA150 150W Power Amplifier

 

[rojo]

Mutimeters don't measure impedance. They measure DC resistance, a totally different and unrelated animal.

While impedance is stated in ohms, impedance is based on an AC signal and varies greatly depending on the frequency at which it's measured.

If you look at some measurement charts of speakers you'll be able to see this variance, and it ain't small.

Well, measuring the DC resistance, then, was supposed to tell him whether feeding a plate amp's high level inputs in parallel with his bookshelf speakers would cause a load problem. Between you and the Martin Logan manual, it's now understood that it won't. Point conceded. He doesn't need a multimeter.

This amp might be your ticket, Dayton Audio APA150 150W Power Amplifier

He's not in the market for an amp. He's happy with his amp. He wants a sub.