Welcome! Need support, you got it. Or share your ideas and experiences.
Return to Planar Speaker Asylum
152.135.148.124
Hello All,
I’ve got a few questions about Preamp/Amp/Speaker/Sub hookup, impedance, and loading that I hope I can get some help on.
My system:
Jolida JD100A CDP (tubed out) Line Output Voltage: > 2V, 47 K ohms
Quicksilver Linestage (Tube) Gain is 18 db. Minimum load is 20 K ohms. Output impedance: 100 ohms
Sunfire Stereo amp Input Impedance 30K ohms
Maggie 1.6s 4 ohm
Velodyne MiniVee subAs some of you may know, the Sunfire has “Voltage” and Current” outputs to the speakers. The only diff between the 2 is that the current outs have a 1 ohm resistor in series with the “+” terminals. I had the 1.6s connected as Sunfire recommends: Mid/Tweets to the Current, and Bass to the Voltage for a while, but then switched and I much prefer Voltage to both.
I currently have the sub connected to the output of the linestage, but I’m considering connecting to the Current out of the Sunfire, which leads me to my questions:1. If I connect the 4 ohm Maggies to the voltage out, and the sub to the current out, what impedance will the amp see?
2. With the sub connected to the linestage Pre outs (Tee connects pre outs to sub and amp), is there any loading on the linestage?
3. Is there a disadvantage to connecting the sub via line level connections vs. speaker connections, even if there is no loading on the linestage (question 2).
I realize that the Current out to the sub is not optimal, but who knows. And I'm not even sure why it wouldn't work well since the sub has a volume control.
Thanks for any help.
Mike
Follow Ups:
I reviewed the sub's manual, which is available in a down-loadable pdf file. It fails to specify the input impedance, except to state that the speaker-level inputs will not load the amplifier appreciably. It would be a reasonable guess that the speaker-level input impedance is even higher than the line-level, and is probably in the vicinity of 10K to 50K ohms. Thus, you can connect the sub to either the 'voltage' or 'current' outputs and probably not be able to hear a difference in the bass. The amp will see only the 4-ohm Maggie load.I would advise installing series R-C filters across the sub speaker inputs if you decide to connect it that way. Use 10 ohm resistors and 0.01 microfarad capacitors. The purpose is to damp RF ringing in the cable used for the sub connection, as the high sub input impedance will cause the cable to be unloaded.
The sub will have some sort of impedance load to the line-level inputs around 10K to 50K ohms. Placing the sub input in parallel with the amp input may drop the combined impedance to below 20K ohms in the bass. Running the amp input from the high-pass output of the sub may prevent this problem (I don't know, because the published specs are so damned incomplete), but entail the sonic degradation of an extra cable and set of connections per channel in series with the main signal. Try it both ways, if the cables will reach, and see which way gives better sound.
There will be some loss in fidelity no matter which way you connect the sub. It is important to understand the trade-offs, so I suggest listening critically to a revealing recording without the sub connected, then with the sub connected but turned off, then with the sub on but at minimum volume. Do this for each connection method you might want to use. One of the methods will give the least degradation, and will be the better choice. Do all this before attempting to integrate the sub bass with the main speakers.
running the amplifier input through a decent signal capitor instead of the cheap POS usually found in subwoofers where the environment usually makes quality parts money wasted.
♪ moderate Mart £ ♫ ☺ Planar Asylum
Al,
Thanks for the great info. Listening to each configuration sounds like a great idea, so I'll do that over the next couple of weeks or so.
btw - Regarding:
> > Running the amp input from the high-pass output of the sub may prevent this problem < <
I did this (Preamp to sub to amp, all RCA), but the internal filter in the sub cut off everything below 80hz to the amp, and therefore to the Maggies. Not good - The Maggies go down to 40Hz, and I prefer to let them.
Thanks again, Mike
This post is made possible by the generous support of people like you and our sponsors: