Adding a subwoofer to a Van Alstine amp...no problem!

Wayner · « **Reply #20 on:** 17 Feb 2016, 03:48 pm »

Quote from: NIGHTFALL1970 on 14 Feb 2016, 12:56 am

Luke357sig (cool name, I get it!),

The instructions from my Rythmik sub says:

LINE LEVEL/ HIGH LEVEL INPUTS:
Amplifier accepts both line level and high level (or speaker level) inputs. Line level outputs are filtered at 80 Hz. One should use line level inputs whenever possible, except where very long interconnects leads to noise problems."

I say try BOTH if you can and report back to us which one you like better. Hope this helps!

Do not ever send the high output of the power amp to a line level input. Wrong, bad.

'ner

NIGHTFALL1970 · « **Reply #21 on:** 17 Feb 2016, 05:17 pm »

I edited my original comment from above to clarify that where the Rythmik subwoofer instructions say "Amplifier" they are referring to the built-in amplifier of their sub, and NOT your separate Amplifier.

luke357sig · « **Reply #22 on:** 17 Feb 2016, 05:27 pm »

Wayner, I want to try exactly what you did. My question is how you made the connection at your amp terminals to accept two cables instead of one. Thanks.

sunnydaze · « **Reply #23 on:** 17 Feb 2016, 05:36 pm »

Quote from: luke357sig on 17 Feb 2016, 05:27 pm

Wayner, I want to try exactly what you did. My question is how you made the connection at your amp terminals to accept two cables instead of one. Thanks.

You simply put both cables on each amp binding post, exactly as I explained earlier. Just use a different connector (or bare wire) on the end of each cable, although 2 spades is probably doable, if cumbersome.

Doesn't this answer your question? Is there something about your amp binding posts that disallows this?

Wayner · « **Reply #24 on:** 17 Feb 2016, 05:42 pm »

Sure, Sunnydaze has it right. Or like I did, I stripped wire (about 1/2") and put that end into the 5-way binding post hole on the amp (unscrew the post and you will soon see a hole thru the shaft), then I use my BFA banana plug in the plug portion of the binding post.

Wayner

Wayner · « **Reply #25 on:** 17 Feb 2016, 05:43 pm »

Quote from: NIGHTFALL1970 on 17 Feb 2016, 05:17 pm

I edited my original comment from above to clarify that where the Rythmik subwoofer instructions say "Amplifier" they are referring to the built-in amplifier of their sub, and NOT your separate Amplifier.

Good enough, just wanted to make sure the confusion was over. Thanks Nightfall....

Wayner

Wayner · « **Reply #26 on:** 17 Feb 2016, 06:01 pm »

If you want to use just plain speaker wire over to your sub, just use the wire holes in the binding post:

Then if your speakers have banana plugs, you can use the plug holes on the binding posts:

Or if you just have plain old speaker wire, and its not jumper cable size, you could put both in one hole:

The binding posts shown are the actual model that Frank uses.

Wayner

luke357sig · « **Reply #27 on:** 17 Feb 2016, 06:27 pm »

Thanks guys! That helps. Was just trying to visualize a nice tight fit will all those cables to the amp.

avahifi · « **Reply #28 on:** 17 Feb 2016, 07:41 pm »

Or - - - you could simply try these" http://www.newark.com/pomona/1330-2/double-banana-plug-15a-screw-red/dp/77B1864

One set plugs into the speaker terminals on the power amp, the second set plugs into the first set.

However --- my own observation regarding whether to use line level or speaker level connections to a subwoofer, assuming subwoofer(s) with built in plate amp and crossover are:

If both choices are available I suggest using the line level outputs from your preamp to drive the subwoofer plate amp(s). Using speaker level outputs you are essentially putting the bass range of two power amps in series, the one driving the main system followed by the subwoofer amp. Perhaps this might lead to less defined bass response than just running the signal at line level directly to the subwoofer amp.

Just thinking.

Frank

Wayner · « **Reply #29 on:** 17 Feb 2016, 10:15 pm »

Frank,

Most subs that have this capability have something on the order of 150,000 ohm input, which is so very small, it should have no effect what so ever on the amp. However, it is not known brand by brand what the particular input impedance is, so owners will have to find that out on their own if this method is right for them. I have run my REL and my old AR/Sunfire in this fashion and you've heard the one combination. Plenty dynamic......

Wayner

ArthurDent · « **Reply #30 on:** 17 Feb 2016, 11:16 pm »

Ok, perfect timing Wayner, after our 'chat' I was wondering about this arrangement. So while it wouldn't be a question with the FV Ultra 550 amp, with the Ultra Valve would I run both additional red leads from the 4 ohm taps currently being used for the Song Towers, or possibly use the 8/16 ohm taps not being used ? My guess is 'Yes, the 4 ohm', but figured I'd ask.

Going back to Frank's comment, my Pre-s both have 2 line outs as shown below. (on-line pic from TAS of Frank's CF)

My sub has either a single 'Sub-in' (Pre out line level input), or L/R red/black high/speaker level inputs. As you note, I see no reason to run what I believe to be a higher quality signal from my AVA gear thru the wiring & crossover in the Outlaw, then to the STs.

To achieve the line level dual channel input for the sub I'm thinking something like this would do the trick. I have an RCA sub cable from an earlier setup for the run to the sub.

Thoughts/comments ?

I use something similar to this

on my old Velodyne CT-100 to split the sub-out from my HT receiver to the sub-in L/R on this unit.

This unit was obviously setup to be used either way, before the single sub-ins/outs became standard. (stock on-line pic)

Wayner · « **Reply #31 on:** 17 Feb 2016, 11:26 pm »

I don't like putting two amps in parallel (maybe Frank disagrees) unless they are identical. I always felt that the inferior amp would bring down the superior amp because of the shared connections. That might be from an episode that I had at once, and thought doing that route was very less then ideal.

Certainly, there is no reason why a guy can't try either route. I like your Y-cable (I think) from the second preamp output (all of Frank's preamps have 2 outputs) and then off to the subs LFE line level input. I'd try either one, and see if you can tell the difference.

My REL T5 is coming off of my Sunfire II amplifier in the digital room from it's speaker outputs (as REL prefers their customers to connect) and that lets my Martin Logans alone and also allows the sub to fill in the bottom end, where the MLs just can't reach.

Experiment! Just do it common sense wise (no amp output going into a line input), or other goofy ideas that could end up with smoke.....

Wayner

NIGHTFALL1970 · « **Reply #32 on:** 17 Feb 2016, 11:39 pm »

This is from the Rythmik Audio instructions:

http://www.rythmikaudio.com/download/A370PEQ3_quickguide.pdf

ArthurDent · « **Reply #33 on:** 18 Feb 2016, 12:03 am »

Understand Wayner, I'd dumped the dual/parallel amp idea based on your prior comments. It would be an either/or, 1 amp only. So everything off of the 4 ohm taps or could the sub feeds come off of one of the other taps without causing problems for the Ultra Valve ? With the hybrid or other SS amp your diagram covers the question.

Wayner · « **Reply #34 on:** 18 Feb 2016, 12:52 pm »

I would come off the same taps as your mains speakers.....

avahifi · « **Reply #35 on:** 18 Feb 2016, 02:20 pm »

Whoops, using a Y adaptor to sum the output of L and R preamp output to feed a mono subwoofer also shorts the other set of L and R outputs on the preamp together so you will get mono sound from the whole system.

We provide dual audio output jacks on our preamp, but they are internally in parallel. To use a Y connection on one set of outputs it would be necessary to have a second set of line audio circuits internally to isolate one set of audio outputs from the other, or at least active buffer circuits and that would mean a more expensive preamp. We can do this of course as an extra cost option, but with stereo line level inputs on the subwoofer plate amp it is not necessary.

Regarding my thoughts about speaker level subwoofer connections, I am not concerned at all about the input impedance of the subwoofer plate amp loading the main amp down. I just suggest that the bass signal needs to go through two power amps in series, first the main amp and then the plate amp. I just think that two amps in series probably is not the path to better sound.

Frank

Wayner · « **Reply #36 on:** 18 Feb 2016, 03:19 pm »

Users have to be sure that their sub-woofer uses a dual wound voice coils (then in a sense, its a "stereo" sub-woofer. However, in ArtherDent's case, he only has an LFE connection for line level, so Yes, I suspect it does not have a dual voice coil.

Wiring the sub thru the speaker outputs may not be quite the ideal situation, but it doesn't have a micro-processor to slow down the signal chain, like when going thru the LFE. Also preamps with an LFE output will put the mains in "small" speaker category and roll off the bottom at some select-able cross-over point (which too is bad), because that point is generally higher then what the mains may go down to. The higher cross-over point will make bass more directional and make blending more difficult, at least in my opinion. Since getting my REL sub, I would never go back to using any kind of line level outputs from my preamps. The bass is much easier to blend and supports the mains, rather then cutting off the mains "feet" so to speak and putting its own bass in its place (which then could put more stress on the sub). It's not the normal thinking, but I like the concept of leaving the mains alone and letting the sub do it's job (and not somebody elses) by supporting the mains woofers, not replacing them.....

Wayner

ArthurDent · « **Reply #37 on:** 18 Feb 2016, 03:51 pm »

Thanks 'ner, Frank. Seems I remember you saying that elsewhere on the line outs Frank. Not sure the sub is mono with the single coax feed, would that be standard output from an HT receiver sub-out ? My old Yamaha surround, new Yamaha HT receiver, and Outlaw Pre-Pro only had single sub-out connections. I don't find the manuals saying whether that output is mono/stereo. I had, probably mistakenly, figured it would be like the coax I run from my USB M2Tech on the computer to my Inday switcher, then to the DAC. The computer audio output is stereo thru the single feed. .........

Well, while writing this appears you answered the 'stereo' vs 'LFE' single sub-out question 'ner.

I may give the 2nd pair of amp leads a try, see how it works. I've survived with 2.0 channel this long, and being a big believer in the 'kiss' principle 2.1 may not be worth the added wiring/circuitry/effort for me. There are other equipment areas of higher importance than a quality Sub on the list. Appreciate everyones' input on the topic.

JD

Wayner · « **Reply #38 on:** 18 Feb 2016, 04:12 pm »

Some subs have stereo line inputs to accomodate preamps with no LFE out, but a second set of pre-outs. My AR/Sunfire does, my REL does not. I believe that most modern day subs will not have a set of "stereo" line level inputs. LFE outs from modern multi-channel preamps is a processed signal, combined into a single channel (hence, 5.1, 7.1 etc.) and most will even send the lowest bass signal from the surround speakers to the sub-woofer. Its a processed signal.

'ner

avahifi · « **Reply #39 on:** 18 Feb 2016, 05:40 pm »

Wayne is correct. Many HT processors have a single mono low frequency output. This is isolated from their normal main stereo outputs and is after some kind of internal frequency shaping circuits. This permits use of a subwoofer - plate amp with minimal signal processing electronics.

We do not provide that kind of HT processing in our high fidelity stereo audio preamplfiers, both sets of stereo audio outputs are in parallel and are full range. This assumes that your subwoofer plate amp has stereo line level audio inputs and has the necessary crossover circuit built in to isolate the preamp input channels from each other.

If all else fails, speaker level connections usually work well too, despite my reservations.

Frank