Tweed Deluxe Output Transformer Upgrade Experience

sds1

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I think that there's no way that 4.2k vs 4.7k could make such a profound, drastic difference in the playing experience.
Yeah this seems less dramatic of a difference than the 5E3. The power supply requirement only drops by about 20mA in this case.
 

Lowerleftcoast

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Since these output transformers are *in hand* can we get some numbers?
What are the resistances. This will give an indication/comparison of wire size.
You have mentioned some turns ratios. What specifically is the ratio?
What are the measurements of the EI laminations HxWxD?
Can you tell if they used paper or plastic?
Any idea of the how many layers of windings.
How much do they weigh?

IOW there are plenty of variables. Can we narrow down a few?
 

gabasa

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Since these output transformers are *in hand* can we get some numbers?
What are the resistances. This will give an indication/comparison of wire size.
You have mentioned some turns ratios. What specifically is the ratio?
What are the measurements of the EI laminations HxWxD?
Can you tell if they used paper or plastic?
Any idea of the how many layers of windings.
How much do they weigh?

IOW there are plenty of variables. Can we narrow down a few?
Sure, I'd be happy to help. I just might need a day or two to get to it because we're finishing home renovation #3 for the summer, so it's been really busy.

The 50246 style OT and the 125A1A style OT are already installed into my 5E3 Deluxe and 5F10 Harvard builds, and all I can say is that it's hard to stop playing these amps because they sound intoxicatingly good ... beyond anything I've played before. However, I have their tweed Bassman PT and OT on my desk, right beside the Hammonds I just removed from one of my old Bassman builds. I'll post the numbers for everything that's within my means to measure, for comparison.

I don't think I mentioned ratios, but I can certainly measure resistances. Which are you interested in?
 

gabasa

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However, in narrowing down variables, there are ones that are not observable.

I know that they use some kind of higher quality layered inulation materials and not bobbins, apparently as in the '60s and '70s. They use a higher quality magnet wire than most companies, with a higher temperature grading. They also use higher quality lamination materials than most. I can't measure any of that.

The quality of construction, as well as some of the construction methods, can't really be measured. They also have a lacquering process that they say ensures a very long life.

These transfomers sound "old," in a very, very good way.
 
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Lowerleftcoast

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I don't think I mentioned ratios, but I can certainly measure resistances. Which are you interested in?
Both.
The ratios will be telling if they are off by a substantial amount. The resistances will indicate if the wire size is similar. There may be many more turns with smaller wire. For instance the pro jr and blues junior have primary of 7k/8 Ohm secondary yet the wire measures 100 Ohms. The Classictone 5E3 8k primary measures ~350 ohms.
 
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gabasa

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Both.
The ratios will be telling if they are off by a substantial amount. The resistances will indicate if the wire size is similar. There may be many more turns with smaller wire. For instance the pro jr and blues junior have primary of 7k/8 Ohm secondary yet the wire measures 100 Ohms. The Classictone 5E3 8k primary measures ~350 ohms.
So you mean the OT primaries and secondaries?
 

Lowerleftcoast

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So you mean the OT primaries and secondaries?
No, I mean winding ratios and primary resistances. The secondary resistances are such small resistances, it would be hard to to make reasonable generalizations.

I have observed the 5E3 with a 6.6k primary winding sounds/acts much different than a 5E3 with an OT with ~8k primary. I assume a 12k primary would at least act differently than a ~8k.

Getting back to the Blues Junior OT. It is known for lack of bass. I assume that is due to having fewer turns but there may be more to it than that. Some of the *upgrade* transformers are the same size so it doesn't seem the size is the difference in bass response.
 

gabasa

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One thing I just realized is that the Pacific OT I have on my desk is their Blonde Bassman OT. I bought it because I wanted the 4 Ohm output for use in my 2x10 tweed Bassman amp. This means it's slightly different than the one everyone's been drooling over that's in my 4x10.

The Hammond 1760K is what I recently took out of my 2x10 Bassman. I originally purchased it (years ago) because it has a 4 Ohm secondary.

This makes a bit of an apples-to-oranges comparison, but here's the info nonetheless.

Hammond 1760K

Primary impedance (spec): 4.0k
Primary resistance (measured): 88.8 Ohm
Lamination (L): 3.753"
Lamination (H): 3.141"
Lamination (D): 1.359"
Weight: I don't have my scale handy, but this one's a bit heavier
Winding Sections: Unknown
Bobbin: Paper
General Impression: Lacks bass, very bright. With very fat, dark speakers however it can sound good so it needs careful speaker selection.

Pacific Audio Magnetics

Primary impedance (spec): 4.6k
Primary resistance (measured): 91.9 Ohm
Lamination (L): 3.754"
Lamination (H): 3.132"
Lamination (D): 1.252"
Weight: I don't have my scale handy, but this one's a bit lighter
Winding Sections: PAM uses interleaved windings on their OTs (eg. 4, 5 or 6 CW/CCW sections) depending on the OT they're cloning.
Bobbin: None; PAM uses higher quality layered insulation materials to better replicate vintage OTs.
General impression: I haven't used it yet, but if it sounds anything like their tweed Bassman OT, I'll be completely blown away again. That one was very clear and open with a huge bottom end, and three dimensional.
 
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2L man

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OT winding ratios are very fast to measure just feeding Mains AC between anode wires and then measuring exact Mains what it is as the moment and all outputs. When OT has wires I tape them to table top so that they do not short and tack solder a scrab Mains cable.
 

gabasa

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OT winding ratios are very fast to measure just feeding Mains AC between anode wires and then measuring exact Mains what it is as the moment and all outputs. When OT has wires I tape them to table top so that they do not short and tack solder a scrab Mains cable.
Ok, I'll hook them up to AC and measure. I might have an AC wall wart I can use for this, just because I feel that it's a bit safer.
 

gabasa

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I hooked up the two OTs on my bench to an AC wall wart and measured the following:

Hammond 1760K

Primary: 14.89V
Secondary (4 Ohm): 0.47V

Pacific

Primary: 14.89V
Secondary (4 Ohm): 0.45V
 

NTC

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First one is 4015:4 ohms. Second is 4379:4 ohms. Not a HUGE difference.
 

Kevin Wolfe

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A Variac is handy for this kinda work. You can set the a/c to an even number, verified with a DMM, and make the math much quicker.
 

NTC

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You measured the primary resistance for both OTs. Did you measure the resistance of both HALVES of the primaries? I am sure the Hammond won't have the same resistance for the two halves, but perhsps the PAM has better matching between the halves?
 

gabasa

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You measured the primary resistance for both OTs. Did you measure the resistance of both HALVES of the primaries? I am sure the Hammond won't have the same resistance for the two halves, but perhsps the PAM has better matching between the halves?
As percentages:

Hammond:
51.45% of the wind is on one side and 48.55% on the other.
Pacific: 50.11% of the wind is on one side and 49.89% on the other.
 

NTC

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The Hammond was better than I expected. The PAM was just what I expected - better matching. Probably due to the interleaving. Just part of a larger story. Thanks for taking the data @gabasa
 

dwindover

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Hello - not to jump on this late, but this is a very interesting thread. I'm glad to see Pacific has jumped on board and that their transformers are performing well. Very interesting specs, for sure.

My thoughts on their 5e3 OT are that if the reverse engineering is correct, and that the primary numbers are so high resulting in lower output, that makes sense according to many of the decisions that Leo was making at the time based on the preservation of the fragile Jensen speakers. For example, the OT's for the Bandmaster/Super/Pro amps were definitely under-built, emphasizing the top end and reducing the bottom in order to protect the speakers.

So - does a higher primary sacrifice overall output and bottom end while increasing some clarity?

What are peoples' thoughts on the Soursound site regarding the 108 transformers? The 108's seem to be a short-lived, unique design as well, seemingly emphasizing high end clarity.
 

no doz

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loved reading this thread. it's always amazing to me what a wealth of knowledge users on this forum have
 




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