Firehouse
25 posts
Nov 10, 2012
10:25 AM
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I got a New amp , Well new to me..lol.. It's a early 60's ,i don't know for sure what year, Wards/Airline Model 9005 2-12's and the tube lay out is 5y3gt,6au6,12ax7,6c67,6l6,6l6, plus another 12ax7 in the top(strange). The thing is Mojo cool and sounds pretty good too. I think it should be louder tough, maybe new speakers are needed? This is where my Question came from. The speakers are wired in what looks like series,but the ground from the amps OT and the ground from the second speaker are wired to ground together on the amp chassis. Is this Right?? the speakers are 14.2/14.5 ohms so 16ohms , Does this mean the OT is 32ohm?? Thank you for your help, i sure do need it,this thing has my head hurting. And i can't find a Schematic for it online either...ERRR.. ----------
Matt Freshour
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5F6H
1413 posts
Nov 10, 2012
11:16 AM
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They often had preamp tubes in the top chassis, so that users could use the inputs & controls without getting down to floor level.
6CG7 means that it might be a similar vintage to the 1433, for which there is a schem, but this is a 1x15" amp, check out shots on line & compare, or upload shots of your amp to a hosting site & link to them here.
Why do the speakers "look like" they are series? A 32ohm OT would be very unusual. Please describe the wiring to & from each "+" & "-" speaker terminal.
If I am right about this being of the same vintage as 1433, then these amps are not particulary loud, compared to 2x6L6 amps of the same age from Fender for instance. If the OT common wire is grounded on the chassis, then at least one wire from the speakers will terminate here too.
The are many other reasons why performance on an amp of this age might be below par. You could try disconnecting the speakers from the OT (with the amp unplugged from the wall AC) and putting a 9v stop box battery to the terminals of each speaker to check that the cones move properly, with a sharp "crack" or "dock" sound"...if there is no sound from the speaker, or you are not sure whether there was a sound or not, then the speakers might need reconing/replacing.
Are you sure that there is just one OT...these amps did not typically have chokes?
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Last Edited by on Nov 10, 2012 11:25 AM
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Firehouse
26 posts
Nov 10, 2012
11:38 AM
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The speakers are both working, the OT has two wires one yellow + , one Black -, The + goes to the + connection of the right speaker. The - connection of the right speaker has a wire connected to it that runs over and is connected to the + connection of the left speaker. The - connection of the left speaker has a wire that runs down and is connected to the chassis. At the same place the - (black wire) from the OT is also connected. I also thought that a 32ohm OT was odd, and thought this may be part of the volume issue. The amp is not sick sounding, i just thought i should be louder. Thank You for your responce!!!! i will look at the model you suggested now..
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Matt Freshour
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5F6H
1414 posts
Nov 10, 2012
12:08 PM
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Well, agreed, it sure does look like you have a 32ohm speaker load.
Any codes on the OT that you can see? any sign that it is not original?
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tmf714
1344 posts
Nov 10, 2012
12:30 PM
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is this the amp?
Here is the link to the page- http://www.harmonica-amplifier-microphone.com/modele.php?marque=Airline&modele=62-9005
Last Edited by on Nov 10, 2012 12:40 PM
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Firehouse
27 posts
Nov 10, 2012
12:31 PM
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I took the bottom chassis out ,and no. i can't find any numbers on the OT. it does look original. no signs that it has been changed that i can tell anyway. looks like its had the caps changed, they look newer. It didn't seem like anyone had had it apart in a long time though...lol... The amp does look like the 1433, but just the bottom chassis. The top Looks like the 1396 as far as inputs and knobs..the bottom though is JUST like the 1433 from outward appearances. Little bitty OT and all...lol...i just looked at pics not schematics yet.
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Matt Freshour
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Firehouse
28 posts
Nov 10, 2012
12:35 PM
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YES!! that is the Same as mine...
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Matt Freshour
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Firehouse
29 posts
Nov 10, 2012
12:55 PM
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OK? yep i have an amp just like that. SO it put less strain on the amp to run it that way? I just found it odd, I was just looking at the Schematic for the silvertone 1433,The bottom Chassis,tubes, PT,OT ,looks the same. It has an 8ohm output, So if mine is the same, It would be less strain to run a 32ohm load on a 8ohm output?
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Matt Freshour
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tmf714
1346 posts
Nov 10, 2012
1:16 PM
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Why would you be looking at 1433 schematic?
All the 1433 amps I have seen carry a single 15" speaker-
Now the 1474 is a twin twelve,but uses 4 6L6 tubes.
Last Edited by on Nov 10, 2012 1:49 PM
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Firehouse
30 posts
Nov 10, 2012
1:21 PM
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On the advice of another forum member. It also makes sense that they would have used the same parts on different models/brands when they made so many. even models with different size speakers. the OT doesn't know if it is a 8" 12" or 2x15"s as long as it gets the right resistance. I am only an amature at amp electronics so my logic is probly way off.
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Matt Freshour
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Firehouse
31 posts
Nov 10, 2012
1:41 PM
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The thing is i don't know what that resistance is supost to be. looking at the site with the pics of my amp there is one model 62-8500 that is the same just a different color.and ceramic speakers. it's schematic says it takes a 4ohm load....omg
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Matt Freshour
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5F6H
1415 posts
Nov 10, 2012
1:41 PM
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I'd be happier if we could see the speaker wiring on the web site pics posted by TMF714, but I'd typically like to see a higher than rated speaker load on the OT than a lower than rated one.
After a point going higher can cause issues too. But as we don't know what the datum is that we are dealing with, I don't want to worry you unnecessarily.
I guess if the amp has survived this long, carry on as is, unless any further details come to light. A tech could check "turns ratio" & "primary impedance" for you at the same time that any other work needed doing to the chassis...maybe something to bear in mind?
@JD Hoskins - Yes, a Red Bank, New Jersey Dano.
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tmf714
1347 posts
Nov 10, 2012
1:51 PM
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As long as you are still refering to the OP-YES -it does make a difference-that is where the series and parallel speaker wiring comes into play.
Test with a multimeter-4,8 or 16 ohm could be the reading-but I will bet it reads 8 ohm.
Last Edited by on Nov 10, 2012 1:53 PM
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5F6H
1416 posts
Nov 10, 2012
1:45 PM
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@TMF714 "Why would you be looking at a 1433 schematic?"
If you know where we can see a 62-9005 schematic then please feel free to point us in that direction...otherwise the 1433 seems to be the closest schem we can find.
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5F6H
1417 posts
Nov 10, 2012
1:57 PM
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@tmf714 "Testwith a multimeter-4,8 or 16 ohm could be the reading..."
What is this test exactly?
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Firehouse
32 posts
Nov 10, 2012
2:02 PM
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http://www.harmonica-amplifier-microphone.com/modele.php?marque=Airline&modele=62-8500&dossier=airline&img=./airline/62-8500/images_site/62-8500(7).jpg Thank you all for your help! 5F6H this amp is a closer model. infact it looks exactly like it ,with the exception of color and ceramic speakers.I found a schematic for it that calls for a 4ohm output.on bargain bin amp heaven. ----------
Matt Freshour
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5F6H
1418 posts
Nov 10, 2012
2:08 PM
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@Matt, tube compliment for the 62-8500 schem at Schematic Heaven is very different to the amp shown at www.harmonica-amplifier-microphone.com ...I wouldn't read too much into it.
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Last Edited by on Nov 10, 2012 2:13 PM
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tmf714
1348 posts
Nov 10, 2012
2:31 PM
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"@tmf714 "Testwith a multimeter-4,8 or 16 ohm could be the reading..."
What is this test exactly?"
This would be a speaker resistance test-exactly.
Resistance mind you,not impedance.
Last Edited by on Nov 10, 2012 2:32 PM
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5F6H
1419 posts
Nov 10, 2012
2:25 PM
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We already know that the nominal impedance of the speaker harness, as the amp came, is 32ohms.
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tmf714
1349 posts
Nov 10, 2012
2:37 PM
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"A 32ohm OT would be very unusual. Please describe the wiring to & from each "+" & "-" speaker terminal."
Then-
"Well, agreed, it sure does look like you have a 32ohm speaker load."
Is it ,or isn't it? Have you seen the amp personally?
Edit for spelling-
Last Edited by on Nov 10, 2012 2:37 PM
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Firehouse
33 posts
Nov 10, 2012
2:42 PM
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Thank you again everyone, i didn't know about that schematic, i will not believe it.. TY JD i will ask him. These amps are so neat untill......lol..... i still think they are neat and enjoy the challenge/learning they give me. Man they sound good when they are right :) I am very thankfull that there are people who have and, are will to share the knowledge they have gained so freely. Thanx ----------
Matt Freshour
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5F6H
1420 posts
Nov 11, 2012
2:41 AM
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No, tmf714 I have not seen the amp personally...this is why I would ideally like to confirm whether the 32ohm speaker load (as described by Firehouse's description of the speaker's DCRs and precise description of the hook up) is as the factory intended.
You seem very sure that it is...so, you have seen the amp in question, personally? What's the turns ratio? Without that everything is conjecture.
However, I do agree that running a larger than intended load is usually safer than a smaller than intended load...within reason.
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htownfess
270 posts
Nov 11, 2012
4:21 AM
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Something that helps 1433s in the power department is to warm up the bias by changing the main cathode resistor--stock, they tend to run 50 ma or under, and revving them up toward 60 ma sounds better and puts out more volume. Not a huge power increase, but enough to make you believe it's a twin-6L6 amp. Check on how that Airline is running. The warmer bias works the 5Y3 pretty hard, so you might consider switching to a Weber Copper Cap for reliability. The plate voltage in the 1433 is so low that 6L6GCs can handle the higher bias just fine; might be marginal with 5881s.
JTThirty has got a 1433 that pushes 4x10 well after we did this & some other stuff to it.
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Firehouse
34 posts
Nov 11, 2012
8:36 AM
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That sounds very interesting.Prob more than i wanna do myself,i will need a tech for that..lol... I did wire the speakers up in parallel, To give an 8ohm load. Wow ,Much louder,more bite/growl, sounds better!! What are the dangers if this is not right?
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Matt Freshour
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5F6H
1421 posts
Nov 11, 2012
9:58 AM
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@ Firehouse:"I did wire the speakers up in parallel, To give an 8ohm load. Wow ,Much louder,more bite/growl, sounds better!! What are the dangers if this is not right?"
Here's a thought, "It was sounding great, then it just went pop/the fuse blew!.." is something amp techs hear a lot...;-)
So firstly, without any hard info to the contrary, we might assume there was a reason that the speakers came wired that way? When you change the speaker load, the primary impedance that the tubes see is also changed...6L6/5881 are usually OK into 2K+ up to 12Kohms, with 2.5K to 8K being "normal" - so you have some wiggle room...but we don't yet know what your primary impedance is.
By switching from 32ohms to 8ohms you have quartered the speaker load & reduced the primary impedance by the same proportion.
As you reduce primary impedance from the datum, you increase current (reduce voltage, for a given power out) through the OT primary winding...more current = more heat and more risk of burning out the winding.
As you increase primary impedance over the datum, you reduce current through the primary winding, at a given power output, but increase the voltage. A speaker's rated nominal impedance is the lowest impedance that it has, at high frequency the speaker's impedance rises...so, in normal operation the OT sees a larger than designed load (at least double). This is why I'd prefer to see a mismatch up, rather than a mismatch down. High primary voltages may lead to spikes that punch through the insulation of the primary winding in *extreme cases*.
This is why I recommend getting a tech to check out your OT primary impedance, so we know what the starting point, or datum, we are dealing with is. With the chassis out & speakers disconnected this can be done in 30mins...it would be wise to have someone give an amp of this age the "once over" anyway.
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Last Edited by on Nov 11, 2012 10:27 AM
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Firehouse
35 posts
Nov 11, 2012
10:05 AM
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Ok, I just had to try it and see :) I have the number of a local amp tech. I will take it in for a checkup. I will find out what the OT impedance is for sure!! And i'll be sure to post it here, i have a feeling that you would like to know as well.
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Matt Freshour
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tmf714
1353 posts
Nov 11, 2012
1:02 PM
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An amp tech may be able to replace some leaky caps,correct frayed wiring,etc,etc.
However-if you are looking for him to give this particular amp more voulme or bite,it's not going to happen.
It came wired in series for a reason-
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Bluzdude46
594 posts
Nov 12, 2012
10:02 AM
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on some of the older amps in that period there is a set of screws to change impedence with a pitchfork type lead to connect and change the impedence. Does your amp have this feature?
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The Original Downtown Philadelphia Fatman... Accept No substitutes!
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