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24.45.17.26
I'm hoping someone can explain to me the purpose of the pre-outs on the rear of my Onkyo Integra A-8190 integrated amp. I have a number of amps and receivers that have both pre out and main in. That I can understand........I've used these to insert various accessories such as equalizers, processors, etc. But what can a single set of pre-outs be used for? I'm curious. Thanks for any info you can give me.
Follow Ups:
I have an A-8190 and the service manual with the schematic, so I can answer your question.
Those aren't really pre outs! Regardless of the labelling. What they are is the power amp output run through a voltage divider to bring the voltages back down to line level, as if it were a true preamp output.
As to use, it would be useful to drive a powered sub with a built in low pass filter, while the A-8190 power amp drives a full range speaker that's a little shy in the low bass. Otherwise, it's pretty useless.
The actual preamp on the A-8190 has a 100% passive line stage, including the tone controls, so it's very clean. The phono preamp is active, as it must be.
If you look through the grill in the cover, you'll see what looks like two power transformers. The one nearest the back is the tranny, the front one is an "true-phase" transformer and seems to be there to correct the power factor of the AC output from the main transformer.
It's a great integrated amp with the right speakers. The A-8190 is the model where Onkyo used all of their tricks.
I did change the speaker output connectors on mine to real 5-way binding posts on 3/4" centers. The ones Onkyo used only look like 5-ways and aren't on 3/4" centers. But that doesn't matter, because they won't accept dual banana plugs. Still sounds good though.
Jerry
Thanks for the great info, Jerry! I acquired this amp a few months ago, but didn't really set it up and listen seriously until yesterday. I've read all your posts on this amp (a major reason why I got it), and I must say that I agree with your assessment. The sound is both powerful and very clean.......and the thing appears to be extremely well-built. I'm using it with a pair of AR2ax (pre-1970, cloth surrounds, orange tweeter) with your resistor tweak as well, and am very pleased with the sound. Concerning the resistor tweak, I did a side-by-side with the 1/2 ohm resistor on one speaker only. The speaker without the resistor, while seeming to have a bit more detail in the upper midrange/lower treble, sounded a bit thin and it seemed as if there was a major depression somewhere in the upper bass/lower midrange output. The speaker with the resistor exhibited (to my old ears, at least) a smoother and more balanced frequency response.....the bass seemed a trifle deeper, and the sound was much fuller and richer, albeit at the expense of some detail. But a very slight boost at 7 khz on the equalizer took care of that. Hey, what can I say..........I'm not a purist.
Today I'll be hooking up a pair of AR3a's to see if there's any difference between the A-8190 and a Carver Receiver @ 130 watts per side that I've been using. The Carver, while clean sounding, does impart a rather lean quality to the sound that I'm hoping the Onkyo will alleviate.
And if I get the urge, I'll try it with a pair of stacked Large Advents.
Thanks for your knowledge and all your help on this site, it's much appreciated.
The 7 kHz dip you hear is probably at the minimum impedance point for the tweeter. I have no problems with using an EQ, although I try not to as a matter of principle.
That amp should do well with the AR-3a's, and may not need the resistor trick because of the fairly low DF of the A-8190 (mine measured 47)and the fact that the AR is a 4 ohm load.
I did try mine with double Advents and it sounded pretty good, although both my pairs were modded and don't stack as well as they did in stock form.
Here's a thought, why not disconnect the jumper on the back of your AR's and make up a little harness that has the 1/2 ohm resistor feeding the woofer, but not the mid and tweeter? It might let you eliminate the EQ.
Jerry
"Here's a thought, why not disconnect the jumper on the back of your AR's and make up a little harness that has the 1/2 ohm resistor feeding the woofer, but not the mid and tweeter? It might let you eliminate the EQ."
I'm not sure what you mean, Jerry. I'm more than willing to try it, but detailed instructions are always helpful to an old guy like me.
If memory serves me there are three terminals on the back of your AR-2ax's. Between two of them is a removeable connection (jumper) that ties the woofer and mid/tweeter sections of the speaker together. If you remove that connection, you can feed the woofer and mid/tweeter separately. The third terminal is the common for both woofer and mid/tweeter.
If you connect the speaker cable to the terminal that feeds the mid/tweeter, you can them run your 0.5 ohm resistor in place of the jumper to the woofer terminal.
If I haven't got the terminals right, let me know how they are, and I'll try again. For one thing, I can't remember the designations of those terminals.
Jerry
Jerry, there are indeed three terminals......1, 2, and T. The strap is between 2 and T. For woofer only operation, you remove the strap. There is no provision (stated in the directions on the back) for tweeter only operation. Any ideas on how to get the resistor to only affect the woofer?
Thanks again.
Joe,
Leave the speaker wire on 1, that's the common terminal. Connect the other wire from the amp to T, that's the tweeter input, then connect the 1/2 ohm resistor between T and 2 (after removing the strap between 2 & T).
That should do it.
Jerry
Thanks, Jerry. I just hooked them up as per your instructions..........and there is a slight improvement. I A/B'd the speakers, one with the original resistor location, and the other as you described so that it would affect only the woofer. There is a slight improvement in the bass, as it seems a tad deeper, and the upper mid/lower treble has a bit more detail. Not night and day, but an improvement nonetheless. In any case, either resistor location is far better to my ears than without the resistor. Maybe it's because I grew up listening to a PAS3x/Dynaco Stereo 70 combo..... subdued highs and a bit tubby in the bass, just the way I like it. :D
My guess is so you can plug a (maybe better or larger) power amp into it, and just used it as a preamp, or plug in a different preamp and use the Onkyo's power amp. Just more versatile that way.
You really should use the tape mon. loops for EQ's and such, they need
a steady line-out voltage....not variable as at the pre-outs, controlled
by the volume control.
Thanks for the tip on the Tape Monitor loops. I've always used them when an amp didn't have pre/main jacks, but I wasn't aware of the reason why they are preferred. It's always nice to learn new things about this great hobby. :D
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