Bi-Amping Altec Lansing Model 14 with Driverack PA2 - Project and Questions
- Thread starter Sam08861
- Start date
Sam08861
Super Member
I've had these for about a year or 2. Got them from a guy who bought them new, but never used them much. Had rotted surrounds, so after a clean up, refoam, recap and some howard's seem to be as good as new.
The only other thing I've had to do was reglue one of the tangerine phase plugs as it was loose. Also, on the stock crossover, I'd done the mod to pull the speaker protection section out of circuit, which improved them just a tiny little bit.
I really like how those manta-ray drivers spread out the sound and I think they sound pretty good with most content. Ran across the audio nirvana article and realize some of it's an advertisement for the driverack, but always wanted to try bi-amping to see what the 'fuss' is all about. The fact that they detailed their x-over points made me feel I had enough info to give this a go. I emailed them as well with my open questions.
If I don't hear back by the weekend, I'll start with some good guesses for the settings and see how that goes.
The only other thing I've had to do was reglue one of the tangerine phase plugs as it was loose. Also, on the stock crossover, I'd done the mod to pull the speaker protection section out of circuit, which improved them just a tiny little bit.
I really like how those manta-ray drivers spread out the sound and I think they sound pretty good with most content. Ran across the audio nirvana article and realize some of it's an advertisement for the driverack, but always wanted to try bi-amping to see what the 'fuss' is all about. The fact that they detailed their x-over points made me feel I had enough info to give this a go. I emailed them as well with my open questions.
If I don't hear back by the weekend, I'll start with some good guesses for the settings and see how that goes.
Sam08861
Super Member
ps... here's the 'restore' thread... https://audiokarma.org/forums/index.php?threads/model-14s-first-day.823237/
Forgot they had stand in pyramid woofers before being fixed.
Forgot they had stand in pyramid woofers before being fixed.
Macaroonie
Super Member
Always switch the PA2 off LAST and on FIRST .
When you first get going start with all of your gains really low just to be sure everything is hunky dory. once you are confident its all running correctly then start winding it up .
You may find the PA2 output is too hot for your domestic amps , you may need to pad them down .
When you first get going start with all of your gains really low just to be sure everything is hunky dory. once you are confident its all running correctly then start winding it up .
You may find the PA2 output is too hot for your domestic amps , you may need to pad them down .
nedseg
Well-Known Member
I have a dbx Venu 360, in a bi-amp + sub configuration, where the LF amp has no gain attenuator, but the Sub and HF amps do.
I ended up 'compromising' at about a 75% setting for both the adjustable amps, then dialed in the dBX gain(s) to match the LF amp (no-attenuator) & woofer output & to achieve ~-20db peaks (the attenuator amps both have level indicators) for my 'normal really LOUD' listening levels...around 95db.
Not very scientific, but seems to work very well.... also sure there's a much 'more correct' way to do it for proper gain optimization.
I'd have to double check to see where the dBX gain's ended up....(huh! Sure is handy to access it right from this PC!! That Venu app is sweet...) - all the dBX input gains are set to 0db, and I do the LF/HF gain balancing in the crossover section - about 6 db difference between them.
No idea if that's the 'right' way to do it...perhaps others will have guidance on that....
Haven't yet engaged the peak limiters, but it's only me using the system.
Totally agree with balanced XLRs - Click, Snap, Done! Sweet.
(In my case, the dBX HF output is feeding a passive crossover for the horns and super-tweeters, so no need for additional protection there.)
Power on/off first/last - agree, though in practice I never turn it off, but do sometimes power down the amps, and always power down the preamps.
Oh, and all my amps are 'pro', with balanced inputs/sensitivity, so no problems with level matching, so heed Macaroonies advice there...
Good luck, and have fun!! ....And report back
I ended up 'compromising' at about a 75% setting for both the adjustable amps, then dialed in the dBX gain(s) to match the LF amp (no-attenuator) & woofer output & to achieve ~-20db peaks (the attenuator amps both have level indicators) for my 'normal really LOUD' listening levels...around 95db.
Not very scientific, but seems to work very well.... also sure there's a much 'more correct' way to do it for proper gain optimization.
I'd have to double check to see where the dBX gain's ended up....(huh! Sure is handy to access it right from this PC!! That Venu app is sweet...) - all the dBX input gains are set to 0db, and I do the LF/HF gain balancing in the crossover section - about 6 db difference between them.
No idea if that's the 'right' way to do it...perhaps others will have guidance on that....
Haven't yet engaged the peak limiters, but it's only me using the system.
Totally agree with balanced XLRs - Click, Snap, Done! Sweet.
(In my case, the dBX HF output is feeding a passive crossover for the horns and super-tweeters, so no need for additional protection there.)
Power on/off first/last - agree, though in practice I never turn it off, but do sometimes power down the amps, and always power down the preamps.
Oh, and all my amps are 'pro', with balanced inputs/sensitivity, so no problems with level matching, so heed Macaroonies advice there...
Good luck, and have fun!! ....And report back
Sam08861
Super Member
Thanks nedseg and Macaroonie!
Been reading up the owners manual and this confirmed the order of operations for powering up/down as you suggest. Also see the suggestion to mute the outputs when making changes to the back switches. Love the fact that the front panel lets you do this at a touch of a button by channel.
nedseg, thanks too for the info on the gain setup Gives me a great starting point.
Macaroonie, I'm thinking to set the 3 limiters to -16db threshold with a soft knee (perhaps sett 3 on the 1 to 10 adjustability) since these are consumer 'amps' as a starting point. Assuming this will dial down the output?
Been reading up the owners manual and this confirmed the order of operations for powering up/down as you suggest. Also see the suggestion to mute the outputs when making changes to the back switches. Love the fact that the front panel lets you do this at a touch of a button by channel.
nedseg, thanks too for the info on the gain setup Gives me a great starting point.
Macaroonie, I'm thinking to set the 3 limiters to -16db threshold with a soft knee (perhaps sett 3 on the 1 to 10 adjustability) since these are consumer 'amps' as a starting point. Assuming this will dial down the output?
Sam08861
Super Member
Just heard back from Harman.
Their tech suggested -10db for the output limiters and +4db for the input. Didn't address using the volume knob as gain, so I like the 75% starting point nedseg suggests. Have a line on a Furman PL-Plus power conditioner so hopefully will have everything I need for a 1st run this evening.
Their tech suggested -10db for the output limiters and +4db for the input. Didn't address using the volume knob as gain, so I like the 75% starting point nedseg suggests. Have a line on a Furman PL-Plus power conditioner so hopefully will have everything I need for a 1st run this evening.
Macaroonie
Super Member
You shouldn't need to use the limiters if you get you gain structure right. My main concern is that the 0dB output from the crossover is a good deal more than the consumer amps will want or need. Approx 1 volt v 100mV Search in line audio attenuators. Rothwell do phono types and there are all sorts in inline XLR format. Typically -10dB -20dB I think -10 would see you right.
Sam08861
Super Member
Thanks again. Perhaps 6 of the below item?
https://www.amazon.com/gp/product/B0024TDIN6/ref=ox_sc_act_title_1?smid=A385A0XNQBW8HY&psc=1
Ps, I had assumed, perhaps incorrectly, that the threshold limiter would reduce the output, so thanks for that.
https://www.amazon.com/gp/product/B0024TDIN6/ref=ox_sc_act_title_1?smid=A385A0XNQBW8HY&psc=1
Ps, I had assumed, perhaps incorrectly, that the threshold limiter would reduce the output, so thanks for that.
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Macaroonie
Super Member
That's the thing. although it's 60 bux , you can do the same thing if you get small resistors and solder them into your xlr's at the x/o output. You should not buy a low impedance attenuator , it will not provide a good match to the amp inputs which will be about 10K.
I'm a bit rusty on the values of R , basically a voltage divider. I'll see if I can refresh my memory , 20 years since I did this. Same problem , JBL M553 x/o XLR line out far too hot for multi channel Rotel power amp.
I'm a bit rusty on the values of R , basically a voltage divider. I'll see if I can refresh my memory , 20 years since I did this. Same problem , JBL M553 x/o XLR line out far too hot for multi channel Rotel power amp.
Macaroonie
Super Member
If you can solder neatly get 6 10k resistors and 6 1K resistors.Prob a good idea to buy a few extra resistors to practice with , You need to organize things in such a way that it all goes away when you put the back of the xlr on.
Basically this is a voltage divider that taps roughly 10% of the voltage. The amps will see a source of 1K against an input impedance of 10K which should be fine.
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Macaroonie
Super Member
Well well you are good to go , just keep it neat and tidy and if you can insulate the new joint so there is no short to any of the other pins. It'll all depend on the cable actually. some don't like re soldering.
Have fun , that should get you sorted out. The Altecs have a lot to give.
Have fun , that should get you sorted out. The Altecs have a lot to give.
Macaroonie
Super Member
Sam08861
Super Member
Also heard back from AN and lots of great advice and the kind gentleman was even willing to speak to me. So, between Harman, AN and others, lots of different perspectives, but I've got as much information as I think I'm gonna get on this hybrid consumer/pro setup from folks with experience with these specific crossover and speakers. One common theme has been, is that the speakers should sound great once dialed in, so that's encouraging.
Because there are differing perspectives and approaches, I'll use an old Onkyo receiver and those acoustimass speakers as a test bed with CD as a source and the preamp as a selector, in the event it a component beyond the crossover (amp or speakers), unknowingly becomes a sacrificial element. Perhaps I'm being overly cautious, but will share what I find out afterwards. I am beat from a long day at work, so will start the process tomorrow after a good nights rest and a clear head.
Because there are differing perspectives and approaches, I'll use an old Onkyo receiver and those acoustimass speakers as a test bed with CD as a source and the preamp as a selector, in the event it a component beyond the crossover (amp or speakers), unknowingly becomes a sacrificial element. Perhaps I'm being overly cautious, but will share what I find out afterwards. I am beat from a long day at work, so will start the process tomorrow after a good nights rest and a clear head.
Sam08861
Super Member
So the 'test rig' survived without incident. Was guess I was worried for no reason.
The way the Auto level works, the volume know on the 115 will actually come in handy as it will be used to dial in the more efficient horn. Auto EQ/Level 'chirps' are pretty similar to the sound from my home theatre's audessey setup, but the RTA mic seems to be much better than the Audessey mic and the calibration is much faster, nearly instant.
I am very impressed with the AutoEQ on this thing. Made these two tiny plastic speakers sound good. Before/after was an amazing transformation. Went from tinny cell phone speaker quality to sounding like bookshelf speakers (the little modern ones, not the vingage wharfedale w60d2 size).
I don't know what digital wizardry is going on here, but somehow these little satellites sound like there is some bass with no subwoofer connected at all.
Now to get down to business with the real thing. Sooo many cables to run, and triple check.
Encouraged by the testing and will report back shortly.
The way the Auto level works, the volume know on the 115 will actually come in handy as it will be used to dial in the more efficient horn. Auto EQ/Level 'chirps' are pretty similar to the sound from my home theatre's audessey setup, but the RTA mic seems to be much better than the Audessey mic and the calibration is much faster, nearly instant.
I am very impressed with the AutoEQ on this thing. Made these two tiny plastic speakers sound good. Before/after was an amazing transformation. Went from tinny cell phone speaker quality to sounding like bookshelf speakers (the little modern ones, not the vingage wharfedale w60d2 size).
I don't know what digital wizardry is going on here, but somehow these little satellites sound like there is some bass with no subwoofer connected at all.
Now to get down to business with the real thing. Sooo many cables to run, and triple check.
Encouraged by the testing and will report back shortly.
Sam08861
Super Member
All done; please ignore the sloppy speaker wires for now. Will get them into the channels I have stuck to the baseboard.
Had a flaky speaker relay in the 117, so switched to the B set of outputs so that took some time to figure out.
Set the crossovers using 12db Butterworth at 1.5Khz and 80hz as described in the article. Initial tests are that the sound is much more balanced, but I'm not totally blown away yet after a few songs.
This is also partially because the sub seems to be picking up a low level hum and that's going to annoy me until I figure that out, so haven't listened too critically.
An improvement in the overall balance of the speakers and whereas before they were very good about putting the voice in the room and perhaps guitar, now piano actually sounds more natural as do drums. A more realistic experience. Did also swap places for the right speaker and tape machine to get the speakers ~8' apart, as suggested by the AN folks.
Running everything with flat auto eq and happy with the sound, but I think the 115's pre section being in the mix isn't helping as the highs aren't quite as clear as before. Might have to figure out how to run some inputs directly to the amp section to see if that helps. Will also try switching the 115/117 to see if that makes a difference.
For the hum, will try the power conditioner out and see if that helps. Once in the past, it was my wifi light switches being in the same circuit that caused a hum, so will try some different outlets as well.
Had a flaky speaker relay in the 117, so switched to the B set of outputs so that took some time to figure out.
Set the crossovers using 12db Butterworth at 1.5Khz and 80hz as described in the article. Initial tests are that the sound is much more balanced, but I'm not totally blown away yet after a few songs.
This is also partially because the sub seems to be picking up a low level hum and that's going to annoy me until I figure that out, so haven't listened too critically.
An improvement in the overall balance of the speakers and whereas before they were very good about putting the voice in the room and perhaps guitar, now piano actually sounds more natural as do drums. A more realistic experience. Did also swap places for the right speaker and tape machine to get the speakers ~8' apart, as suggested by the AN folks.
Running everything with flat auto eq and happy with the sound, but I think the 115's pre section being in the mix isn't helping as the highs aren't quite as clear as before. Might have to figure out how to run some inputs directly to the amp section to see if that helps. Will also try switching the 115/117 to see if that makes a difference.
For the hum, will try the power conditioner out and see if that helps. Once in the past, it was my wifi light switches being in the same circuit that caused a hum, so will try some different outlets as well.