Conrad Johnson PV-1

[Ebryant7]

Hello Everyone!

I’m new here! I’ve been busy putting together a system for my home and I have a PV1 handed down through my family to me at the center of it all.
I’m having it reconditioned right now at Conrad Johnson.
It’s serial number is 1526 and wouldn’t stay on when turned on. Blew the fuse. Anyway, I have a Syzygy SLF870 remote subwoofer and B & W 805 Nautilus Mains. Powering it all is a Moscode 600.
My question is if someone could help me, is I have two sets left/right outputs on the PV1. One set is going to the amp and the other set to the subwoofer. Subwoofer has a built in crossover which I have set at 50HZ. Do I need to add a crossover for
The mains to cut of at 49 Hz?

Thank you so much for any and input on this!

Eric

[AnotherJohnson]

No. As you point out, there is a crossover in the sub.

[admin]

***I deleted the double post.

Welcome to CJO, great to have you with us.

Typically if you have a crossover in the sub (and you want to use the sub), you would just have output from the preamp going into the sub, then the output from the sub going into the amp. In other words, it would be a serial connection and not parallel.

[AnotherJohnson]

***I deleted the double post.

Welcome to CJO, great to have you with us.

Typically if you have a crossover in the sub (and you want to use the sub), you would just have output from the preamp going into the sub, then the output from the sub going into the amp. In other words, it would be a serial connection and not parallel.

Is this an HT connection?

It may depend on the sub I suppose, but I’ve never fed the output of the sub back to the amp.

The sub output is acoustic into the room, no?

Feeding the electrical out put from the sub could be used to feed a second sub, I suppose.

Maybe I could use enlightenment.

[admin]

Typically if you don't have a "sub out" from the preamp (as usually found on home theater receivers) you would put the sub in serial. Some subs have RCA in and out for this, others will connect directly to the speaker wire and via their internal crossover take over the low end output. For example, I think the magnepan bass panels you just wire with the speaker wire from the amp. I always viewed it as the connection will depend on where you have the crossover.

I may also need some enlightenment.

[AnotherJohnson]

With the few subs I’ve owned, there have been two options. Either feed them directly from a set of extra main out jacks on the preamp, or run them in parallel off the main speaker pair.

Either connection to the built in crossover and amp onboard the sub can handle it.

In the parallel wiring scheme off the speakers, the impedance presented by the sub’s input is so large as to not significantly impact the main amp’s load. 8 ohms in parallel with 10000 ohms looks pretty much like 8 ohms to the main amp.

Similarly, the use of both main out jacks if present puts the two amps (main and sub) in parallel, but the two large impedances in parallel still presents a large impedance to the preamp, so it’s happy.

I used to use both main outs when running a sub.

Now I use the parallel with the speakers approach.

I think it maintains the character of the LP275Ms more completely.

I’ve never seen a loop where the signal from the amp is fed to a load and then back to the amp.

Processing and tape loops are different. You leave the preamp at line level, go to the processor for manipulation, or the tape machine to record. Then in the case of the processor, you return at line level and go through the preamp and on to the amp. In the case of the tape machine, you only return at line level for playback, or for monitoring.

YMMV

[Ebryant7]

Thank you very much for the discussion and input.
My subwoofer (speaker box) is wireless and has it own amp. It has a small remote box transmitter that has a left /right coax RCA inputs that I think should be coming from PV-1’s outputs. I have the subwoofer crossover at 50 HZ. Since the PV1 is in the shop still, I’ve been using My NODE as a temporary preamp. It has one Subwoofer out.
When I get the PV1 back I believe I simply connect the two outputs to the subwoofer remote. Then use
The crossover in sub. The other outputs run to the Amp which power the Main 805 nautilus. From what I think I’m understanding is that I don’t need to run another crossover for the main speakers to cut off at a certain low frequency?
As you see I’m quite novice here.
Thanks again for taking
The time
To discuss!

[AnotherJohnson]

I think you’re good to go .

[admin]

I think AJ is correct in that if you have two main stereo outputs you can just use one set to go directly to the sub. Of course not all preamps have two volume controlled outputs.

Ebryant7, are you using a Bluesound Node as the source? If so, there is only one set of RCA outputs so that would have to go to the sub and then sub to amp with another RCA cable.

[AnotherJohnson]

I used to think that a pair of main out jacks was essential for the situation where you wanted to run an active subwoofer.

But I now prefer the configuration of running the subwoofer in parallel off the main speaker.

I came to this by experimenting.

I don’t know what another person might prefer in their system, but experimenting is virtually free.

[AnotherJohnson]

One more comment.

Many of the CJ preamps are inverting, so you end up adding a second inversion by wiring your + speaker wire from the amp to the - speaker input on the speaker and vice versa.

Most subs have their own internal amp to sub wiring, and so you can’t add the inversion to the sub if you go the second main out route.

If you want the original speaker and the sub to be in phase, you set up the main speakers with the aforementioned inversion, and then from the speaker input block, wire plus to plus and minus to minus on the sub. This preserves the phase you chose with the main speaker wiring.

With many subs, like the Martin Logan Balanced Force models, you can adjust phase with a dial on the sub, so there are still ways to get in phase with the main speaker if you choose the second main out as the sub feed. But I think running the sub in parallel with the main speakers is more transparent and requires less fiddling.

Subwoofer bass frequencies are not that directional, so it may not matter in many installations. The keys to good sub matching are patience and critical listening over several programs and several days.

And, of course, the other key to good sub matching is that the sub should be a subtle addition that creates a fullness, but does not call attention to itself. Subs are not to create boom. They are to create a sense of reality.

I was listening to a pair of stand mounted speakers in a showroom this week. My first reaction was “Wow, these have a lot of bass for such small drivers. But as I listened, it sounded uncontrolled, incoherent and sloppy.

I looked for a sub, spotted one, and checked to see if it was being foisted off as a hidddn part of the demo. Sure enough, it was “on and thumping.”

The salesman returned to the room, I pointed it out, and he apologized. He said it had been added that morning without his knowledge. We disconnected it, and the audition was much tighter and realistic. Subs don’t always help, and cheap subs that aren’t dialed in nearly always make things worse unless you’re hoping for boom box type sound.

[admin]

I agree with AJ.

I think if you have the ability to play around with different connection modalities, then try them all. You have nothing to lose and you are more likely to find the best sounding one for your system.

Phase is typically not a major issue as most high end subs have a phase switch. If connected with speaker wire, then it will automatically be in phase with the speakers regardless.

I personally have found pairing subs with high end speakers very difficult. Especially when it comes to planar speakers like my magnepan or previous martin logan's. I will say that martin logan has probably done the best job with creating an excellent combo with their build in subs and planar ESL line of speakers.

In home theater setups it's a different story. First, there is usually a dedicated track specifically for the sub. This is a huge advantage vs trying to use complex crossover systems to pull the low end from a stereo track. So in home theater setups with many speakers (I use a 7.1 system in mine), the sub really is a must. When that big building explodes in the movie, I want my back teeth chattering.

[AnotherJohnson]

I figured there must be some differences in the HT application.

Even the veritable MF5600 doesn’t have enough channels to handle 7.1. Incidentally, there’s an amp with great HT potential, and they have to give them away. If I were thinking about a small scale HT, I’d be looking for one.

[Ebryant7]

Tons of very useful information here. THANK YOU!!

Yes, currently I’m using my Blusound Node as the source and preamp until my PV1 comes back in a few weeks. I also ordered a Rega planar 3 with exact cartridge, and looking for a Sony CDP-XA20ES or something in it’s range. the Node has a subwoofer out and co/ax and a left/right output. Currently the two outputs go to my amp and the subwoofer out to the wireless, crossover/transmitter. When the PV1 returns, I’ll run the node outs to the PV1 and and connect the output off the PV1 to the amp and subwoofer transmitter’s left/right inputs.. I think?
I love and agree with what the intent and use of the subwoofer should be and have since dialed it’s impact back to get the focus off of it and move the soundstage and attention back to the 805 mains utilizing the sub to round out the sound. You can’t really tell where the sub is located in the room
Now because it’s mixed in with the mains making it feel and
Seem as if the bass is coming from them and not a thunderous box in the Corner.

[admin]

Ha,... I also spun vinyl on a planar 3 for years. One of the best entry TT's around. Good choice.

[Ebryant7]

That’s great to hear you like
The Planar 3!! I think I got
A good deal on it. New $999 with the Exact cartridge?
I’m
Quite excited to hear the PV1!!!

[admin]

You should get lots of enjoyment from that setup. The planar 3 has a really great tonearm that they have perfected over the years (I think the RB330 is the latest iteration). They been selling the planar 3 for nearly 4 decades now and have slowly and incrementally made improvements to a turntable that was great from the start. Again, lots of bang for your buck. I was using mine with an entry level dynavector cartridge and it really sounded great.

[roberto]

Hola,
My ET-7 has inverted phase...so what I do is to use the sub with inverted phase too. My ML BF-210 sub has the option to inver it, so my quality bass is awesome.

Great advices to get the best match between the sub and the preamp, even that your sub is not connected physically speaking. It does not represents any load for the amp impedance between the sub and the preamp.

Enjoy your music!

Happy listening!

[AnotherJohnson]

Hola,
My ET-7 has inverted phase...so what I do is to use the sub with inverted phase too. My ML BF-210 sub has the option to inver it, so my quality bass is awesome.

It’s even better than a switch. It’s a continuously varying dial. Very accommodating.

There is a phase shift between the two amps, plus the lack of directionality of the bass, that have to be accounted for … your ears are the best guide.

I’ve enjoyed the BF210. It may be the best sub $3k subwoofer out there.

[roberto]

Aj, I could't said it better...yes, that's the one. And it's true. You can tell by the ear the best position of the varying control for the most natural bass performance.

As I usually say: I do trust my ears, because they are the final judges of the quality of my sound. If the bass is too strong, or if one bass note resonance is evident, with this knob, you can adjust precisely the overall bass performance in your room and your seating position. This knob is a wonderful thing to have.

I love bass, but I do not like it too strong. I like to have the bass player there, at my virtual stage, not to have the player next to me in some musical notes. So a critical listening is a must. The problem is that there are recordings with no bass at all, and others with heavy bass content. Well, I use those with the heavy bass content to adjust the level to a certain point where the musician is there and still you can have that heavy bass musical notes.

This adjustment had worked for me very good, because the people who came and have a listening session, their first comment is regarding the quality bass.

Happy listening!