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Connecting tube amp to sub with speaker level inputs

98.164.188.3
Posted on January 13, 2022 at 13:56:23
LtMandella
 Is it safe to connect my OTL tube amp speaker outputs to both my mains speakers and my powered HSU subwoofer speaker level subwoofer inputs?

I am not currently using a powered preamp, just a passive attenuator.

It is my understanding that for optimal "timing" of the mains vs. sub speakers it is best to drive the sub with the same high level signal as the main speakers.

But is this safe for an OTL tube amp?

thanks,
LT

 

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RE: Connecting tube amp to sub with speaker level inputs, posted on January 14, 2022 at 07:33:34
Bill Way
Audiophile

Posts: 1884
Location: Toms River NJ
Joined: May 28, 2012
Contributor
  Since: December 14, 2012
 Connect the OTL outputs to the high-level inputs on the subwoofer, and run speaker wires from the "output to speakers" binding posts to the speakers.
"Put on your high heeled sneakers. Baby, we''re goin'' out tonight.

 

RE: Connecting tube amp to sub with speaker level inputs, posted on January 14, 2022 at 09:31:02
LtMandella
 Thanks, do you mean from the "output to speakers" binding posts on the sub?

I thought of that but it has a couple drawbacks for me, which is why I would prefer to just connect the outputs from the amp into both the mains and sub:

1: the physical arrangement of my listening room and speakers means I would have to run four speaker cables across my listening room; two from the amp to the sub across the room, and two from the sub back across the room to the main speakers (the sub and main speakers are on opposite sides of the room and I can't fit both on the same side).

2: I believe for that configuration I would be placing the crossover of the HSU in the signal path of my main speakers, which I would rather not do. The DeCapo I speakers you see in the photo have no crossover of their own between the tweeter and woofer (just a high pass cap on the tweeter-the mid woofer rolls off naturally) and I really love the sound.

In the past (using outboard low pass filter which I no longer can find) I found the best integration between main and sub speakers to be when the main speakers continued to have full range signal.







 

RE: Connecting tube amp to sub with speaker level inputs, posted on January 14, 2022 at 10:00:32
Bill Way
Audiophile

Posts: 1884
Location: Toms River NJ
Joined: May 28, 2012
Contributor
  Since: December 14, 2012
 "...do you mean from the "output to speakers" binding posts on the sub?" Yes, that's why I said, "run speaker wires from the "output to speakers" binding posts to the speakers."

It is never good to send speakers a signal they cannot reproduce. All that does is generate heat in the voice coils of the drivers.

Yes, your speakers do have a crossover. That's what that high-pass filter is. The kind of crossover they have doesn't affect how you connect a sub.

"Crossover" is not an evil word. It is not something that detracts from your system's reproduction, put there by designers who want their speakers to sound lousy. It enables speakers to sound their best by sending all drivers signals they can reproduce, and *not* send them signals they cannot reproduce.

WW
"Put on your high heeled sneakers. Baby, we''re goin'' out tonight.

 

RE: Connecting tube amp to sub with speaker level inputs, posted on January 15, 2022 at 13:08:25
LtMandella
 thank you, I should have included a picture in my original post.

So here it is; this is how I would prefer to connect my sub, IF it is safe for my OTL tube amp to connect this way. In my past experience I have found that keeping the Ref 3A DeCapo speakers full range and just using the sub for very low level and very low frequency augmentation of the DeCapos sounded the best to me.

But I don't know if this is safe to do with the tube OTL...




 

It should be safe with almost any OTL, posted on January 18, 2022 at 08:41:37
Ralph
Manufacturer

Posts: 4778
Location: Minnesota
Joined: April 24, 2002
 With our stuff you likely will run into a buzz problem since the output of our amps is balanced (neither side is at ground). But you won't hurt the amp.

I prefer to run a second output from the preamp to the subwoofer.

 

RE: It should be safe with almost any OTL, posted on January 18, 2022 at 08:53:11
LtMandella
 I doubt very much my Transcendent OTL is balanced, but if I hear a hum I now have a clue as to possible reason, so thank you!

 

Its not balanced; you should be OK. nt, posted on January 18, 2022 at 10:18:58
Ralph
Manufacturer

Posts: 4778
Location: Minnesota
Joined: April 24, 2002
 -

 

RE: Its not balanced; you should be OK. nt, posted on January 18, 2022 at 11:08:33
LtMandella
 great, thank you!

 

RE: It should be safe with almost any OTL, posted on January 23, 2022 at 08:01:59
MP
Audiophile

Posts: 44
Joined: July 2, 2001
 I run 2 REL T9i subwoofers in stereo, one subwoofer with one M60, in high level input (speaker output level) balanced mode.

Completely quiet.

Quite happy with the additional bass. Speakers are QUAD 989 or KEF LS50, Zero-former at 3X.

 

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