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  #1  
Old 03-12-2012, 08:47 AM
woad_yurt woad_yurt is offline
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ALtec solid state question....

I have an Altec 1594B amplifier. It's a mono SS amp rated at 100 watts. They used to be used in movie theaters, it seems. I put a guitar through it and used a JBLG125-8 speaker in a remote cabinet. It sounded pretty good and had quite a bit of power.

It's got no case; looks like it was mounted in some kind of rack. I want to use it for a practice amp or maybe PA duty for a single microphone. There are no tone controls, just a giant volume knob, and all of the inputs and outputs are conected with screws.

Before I go soldering up some plugs, jacks and wires, can I put an equalizer in between the amp's input and a guitar or microphone? If so, the EQ I have is stereo. Can I put the guitar into the EQ's right input and then make a jumper from that side's output to the left side's input and then go from the left side's output into the amp? Would it work like having two EQ's in series? For example, it would be cool to hear what it would sound like with all bass/no treble going through lots of treble and minimal bass second. I do the same thing with guitar & amp tone controls and some effects pedals. I sometimes get some cool sounds.

Any info would be appreciated. Thanks.

PS It's one honkin' strong amp for $45.
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Old 03-12-2012, 10:06 AM
donnyjaguar donnyjaguar is offline
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I betcha if you put something like a Boss CE7 before the input it would work great.
Or maybe consider one of those multi-effects digital pedals if you're okay with them.
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  #3  
Old 03-12-2012, 10:28 AM
zenitB zenitB is offline
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My family owned/ran a movie theater for a while and had an Altec set-up like this.
Of course, we tried plugging in to the system with our guitars and I think that you will need a preamp to get what sounds like 100w. Even when we plugged a magnetic cart
turntable into the system we needed a preamp. Also, those amps were intended to update the systems to run films with magnetic sound, we actually had two systems, one was tubes -installed in 1947 and the SS amps later in the 60's; our speakers were also Altecs, the A7.
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Old 03-12-2012, 01:01 PM
woad_yurt woad_yurt is offline
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I don't know much about electronics and couldn't identify preamp circuitry if I was looking at it but, for sure, this thing does indeed crank out what sounds like 100 watts, just as is. I just sold an old 50 watt ss 4x10 guitar amp and the Altec dwarfs it, sound-wise. I have 2 JBL G125-8 speakers, one in it's own cabinet and one in my 2-tube Twin Reverb and this amp Altec pushes them very well. It gets loud enough to be quite uncomfortable. It's pretty cool in that it has 4, 8, 16 & 50 ohm outputs.

I have a mint 15" JBL G135-8 in transit and, with all of the amp's ohm variability, I think I can make a pretty decent set up with this thing. I'm thinking of one G125 and the one G135 in a single, trapezoidal cabinet with a back that I can leave open or seal using a gasketed hatch or cover. But, I digress....

That said, does anyone have any opinions on my EQ-looping questions in the first post?
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Remove V1 & V6. Put the 12AX7 from V1 into V6 and leave V1 empty. Now try the vibrato channel.

Last edited by woad_yurt; 03-12-2012 at 01:22 PM.
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Old 03-12-2012, 03:45 PM
TimmyP TimmyP is offline
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I'd think that the input impedance of that amp would be much too low for a guitar to sound its best (unless the guitar is active). So you need a buffer or a preamp.
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  #6  
Old 03-13-2012, 12:04 PM
donnyjaguar donnyjaguar is offline
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Quote:
Originally Posted by TimmyP View Post
I'd think that the input impedance of that amp would be much too low for a guitar to sound its best (unless the guitar is active). So you need a buffer or a preamp.
I agree with this. Its also why I was suggesting putting a EQ pedal in front of it. The output impedance of the Boss CE7 (and most every pedal) is much lower than the instrument itself and will allow it, even in bypass mode, to drive a typical lo-Z input impedance.

For example, if I record my Tele directly into my soundcard it sounds weak and muffled. Running it through the Boss EQ, even when not on, sounds much better.
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  #7  
Old 03-13-2012, 09:00 AM
woad_yurt woad_yurt is offline
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Please explain. I'm totally ignorant regarding all of this. I can build a house, rebuild a car engine and wire a factory but electronics is my Kryptonite.
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Remove V1 & V6. Put the 12AX7 from V1 into V6 and leave V1 empty. Now try the vibrato channel.
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  #8  
Old 03-13-2012, 11:43 AM
zenitB zenitB is offline
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Quote:
Originally Posted by woad_yurt View Post
Please explain. I'm totally ignorant regarding all of this. I can build a house, rebuild a car engine and wire a factory but electronics is my Kryptonite.
Impedance is kind of hard to explain but in essence, a guitar is a high impedance device ie: it can produce voltage at very low current levels. If it was a low impedance guitar, it would be able to develop much more current (probably why low impedance pickups use batteries)
So, when we plug a high 'Z' guitar into a low 'Z' input, it will make some noise but it won't drive the amp/device in a way that it will make max output or frequency response. Now that I look back on my experience plugging stuff into our Altec amps, it was necessary to turn it up to get decent output and it sounded kinda funky/distorted when it was dimed--something it never did as a theater amp. It could have been that it was either an impedance mismatch or the guitar was too low level to drive the amp.
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Old 03-13-2012, 02:00 PM
woad_yurt woad_yurt is offline
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I managed to find a PDF Altec spec sheet from way back and it says that the source impedance would be, and I quote, "150 or 600 ohms (balanced.)" For input impedance, it says "15,000 ohms (potentiometer.)"

I should mention that I have an Optimus 100 watt PA amplifier, so PA use is covered. I know it's a cheap-o but it'll do for now. I'm more interested in using the Altec for guitar (maybe) or bass (definitely,) although being able to use a microphone in a pinch would be nice. I looked at guitar preamps and there are many types, most with a bunch of included effects. I want as clean a sound as possible from the preamp. If I want to dirty it up, I can use any of a bunch of pedals I have around here.

Some hours later:

I've been on the phone a bit trying to sort this out and someone told me that this would work for me:

http://www.guitarcenter.com/Behringe...esid=102774270

I know it's not the ultra top-of-the-line but if it'll get me functioning for now, it'll do. I just dumped a bunch of money into some old JBLs and don't have a ton to spend on this. If it works out well, I'll upgrade.

Thanks!
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Remove V1 & V6. Put the 12AX7 from V1 into V6 and leave V1 empty. Now try the vibrato channel.
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  #10  
Old 03-13-2012, 03:25 PM
zenitB zenitB is offline
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Quote:
Originally Posted by woad_yurt View Post
I managed to find a PDF Altec spec sheet from way back and it says that the source impedance would be, and I quote, "150 or 600 ohms (balanced.)" For input impedance, it says "15,000 ohms (potentiometer.)"

I should mention that I have an Optimus 100 watt PA amplifier, so PA use is covered. I know it's a cheap-o but it'll do for now. I'm more interested in using the Altec for guitar (maybe) or bass (definitely,) although being able to use a microphone in a pinch would be nice. I looked at guitar preamps and there are many types, most with a bunch of included effects. I want as clean a sound as possible from the preamp. If I want to dirty it up, I can use any of a bunch of pedals I have around here.

Some hours later:

I've been on the phone a bit trying to sort this out and someone told me that this would work for me:

http://www.guitarcenter.com/Behringe...esid=102774270

I know it's not the ultra top-of-the-line but if it'll get me functioning for now, it'll do. I just dumped a bunch of money into some old JBLs and don't have a ton to spend on this. If it works out well, I'll upgrade.

Thanks!
I am in the minority here on TGP, I like Behringer stuff, I'm sure it will get ya goin'.
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  #11  
Old 03-13-2012, 09:09 PM
BOBSMITH BOBSMITH is offline
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I have repaired many Altec 1590 series PA Amplifiers.They are built like tanks and are easy to repair.They used Peerless transformers and used an output transformer believe it or not.Thats how they get 4-8-16-50 ohm(70.7 volt system) outputs.
You got a bargain.
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  #12  
Old 03-14-2012, 05:38 AM
woad_yurt woad_yurt is offline
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I ordered the Behringer preamp. If it works as I hope it well, it looks like it'll make a great amp. I was playing it with a gain pedal and the thing feels like it's going to be a pretty cool guitar head. I don't know about bass yet. I'll post a picture after I make a little cabinet for it.

zenitB: Thanks for the assurance. I was waffling like crazy beforehand until I got your thumbs up. I hate buying things I won't use, you know?
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Remove V1 & V6. Put the 12AX7 from V1 into V6 and leave V1 empty. Now try the vibrato channel.

Last edited by woad_yurt; 03-14-2012 at 12:40 PM.
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  #13  
Old 03-14-2012, 06:24 AM
Reincaster Reincaster is offline
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Would you not need a speaker built for 70 volt systems? Unless these amps have an option to switch to regular 4/8/16 ohm operation.
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  #14  
Old 03-14-2012, 12:43 PM
woad_yurt woad_yurt is offline
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The 70 volt designation is only over the 50 ohm screw. There's 20V over the 4 ohm one and 25V/28V over the 8 ohm one. What's a normal 8 ohm guitar speaker require?
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Remove V1 & V6. Put the 12AX7 from V1 into V6 and leave V1 empty. Now try the vibrato channel.
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  #15  
Old 03-14-2012, 12:52 PM
zenitB zenitB is offline
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Quote:
Originally Posted by woad_yurt View Post
The 70 volt designation is only over the 50 ohm screw. There's 20V over the 4 ohm one and 25V/28V over the 8 ohm one. What's a normal 8 ohm guitar speaker require?
the voltage designations are for speaker systems that run over hundreds of feet and use transformers at the speaker, like some auditorium applications. For you, just use the 8 ohm terminals and you will be fine. I did the same thing on a Boge4n PA amp and it worked great
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