Mesa Boogie Mark II OT Specs

IDDQD

IDDQD

Member
Hello everynyan!

Does anyone know the specifications of the T100-152019 transformer (such as Raa value)?
(not SC-152019B)

This transformer has a power rating of 100 watts and belongs to the Mark II series, specifically non-Simul-Class version (Mark IIB, I believe).
The amplifier features four 6L6GC power tubes.

Or maybe there is a way to measure the Raa parameter safely?
 
Raa is resistance anode-anode or also known as resistance plate-plate. It’s just another way of saying primary impedance of a transformer. You’ll need the resistance value but you’ll also need the frequency it was measured at. Technically it’s an impedance measurement but conventionally that’s how they’re called out in spec sheets.

You’ll need an original to measure it to get the most accurate results.

Since it was designed for 6L6GC I’d assume you could just take the Z anode of a push pull class AB pair from the original tube data sheet used with it and divide by two since it’s non simul-class and 100W.
 
glpg80 said:
Raa is resistance anode-anode or also known as resistance plate-plate. It’s just another way of saying primary impedance of a transformer. You’ll need the resistance value but you’ll also need the frequency it was measured at. Technically it’s an impedance measurement but conventionally that’s how they’re called out in spec sheets.

You’ll need an original to measure it to get the most accurate results.

Since it was designed for 6L6GC I’d assume you could just take the Z anode of a push pull class AB pair from the original tube data sheet used with it and divide by two since it’s non simul-class and 100W.
Click to expand...
🤯
 
Not quite like that.

Based on the reference data, we can get average values.
However, Raa may change slightly.

For example, take Hammond transformers:
> (15W, 2x6V6GT) : 1751M (8k) and 1760E (8.5k);
> (100W, 4x6L6GC) : 1760W (2k) and 1750D (2.35k).

Or Hammond 1750U (1.7k) and ClassicTone 40-18072 (2.2k) - both for 100W amps, 4xEL34 or so.

According to the reference information for 6L6GC, the Raa value can range from 3.8k to 6k - for two tubes in Push-Pull connection.
Therefore, dividing by two we get 1.7k to 3k for four tubes.

Perhaps there is another way? Or specific information about the T100-152019?
 
You state not quite like that but literally use what I stated to provide an upper and lower limit to work with.

You’re welcome and the information you’re seeking has already been covered as well:

glpg80 said:
[…]

You’ll need an original to measure it to get the most accurate results.

[…]
Click to expand...
 
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IDDQD said:
Alright, I've got one. What should I do next?
How to measure Raa?
Click to expand...
A VNA and an LCR meter. You’ll have to do research to create a testbench and know what parameters to gather. It’s also worth noting you’ll have to disassemble the OT basically destroying it to get all the parameters. Winding count, type of wire, bobbin material, number of laminate plates, type of plate arrangement, etc. etc.

The next easiest solution is to send it to Mercury magnetics and ask them if they will characterize it and clone it. They charge a lot to do so but it’s fair since it’s a one off, Probably cheaper and most economical if your only care is this one transformer. Bench equipment gets expensive fast.
 
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glpg80 said:
A VNA and an LCR meter.

You wanted to argue with me about another way rather than take the most logical and cheapest method of using what you can from data sheets. Since that isn’t good enough, now you get to invest in high quality bench equipment and characterize it yourself.
Click to expand...

Please quote me where I tried to argue with you.
You suggested using the data from the datasheet, so I wrote an example to show that there may be small differences within certain limits.
Then you repeated again that in order to get data about a specific transformer, I need to have it.
And so the transformer came to me, even though I ordered it before I started this topic.
I ask the question again, and I get a strange attack from you, as if I offended you in some way.
Is something wrong?
 
IDDQD said:
Please quote me where I tried to argue with you.
You suggested using the data from the datasheet, so I wrote an example to show that there may be small differences within certain limits.
Then you repeated again that in order to get data about a specific transformer, I need to have it.
And so the transformer came to me, even though I ordered it before I started this topic.
I ask the question again, and I get a strange attack from you, as if I offended you in some way.
Is something wrong?
Click to expand...

You want something you don’t have the knowledge or actual resources to gather. Send it to a company to characterize if you’re wanting more information than what’s provided in this thread.

Yes I was offended when I told you exactly what you needed, you replied “Not quite like that.”, and then proceeded to argue with me against my own suggested method demanding “another way”.

Also re-read the post, it was edited afterwards to help others who are likely in your boat.

So since you like to use strong arm argument techniques I’m not helping any further and you need to understand the cost and investment required for the answers you seek. After that you’ll realize it’s cost prohibitive for one transformer and call a company to characterize and clone it for you. Or just use an average of the impedance range method I suggested and move on.

Regardless the one owed an apology here is me. I’m only trying to help and I don’t argue. I tell it like it is. It’s not my fault if you’re dissatisfied.
 
glpg80 said:
Yes I was offended when I told you exactly what you needed, you replied “Not quite like that.”, and then proceeded to argue with me against my own suggested method demanding “another way”.
Click to expand...

"Not quite like that." means it's not enough to take the datasheet's parameters and divide by two... I suppose it was clear.
Anyway. You're making it up out of the blue.
My question is simple: how to measure the Raa of a specific output transformer.
I don't need wiring counts, core specs, or anything like that. Just typical specs of.
For using, not copying.

I have an LCR meter (DER EE DE-5000), hope it's good enough.
 
IDDQD said:
"Not quite like that." means it's not enough to take the datasheet's parameters and divide by two... I suppose it was clear.
Anyway. You're making it up out of the blue.
My question is simple: how to measure the Raa of a specific output transformer.
I don't need wiring counts, core specs, or anything like that. Just typical specs of.
For using, not copying.

I have an LCR meter (DER EE DE-5000), hope it's good enough.
Click to expand...

it’s an impedance measurement. Ground one side, source the other, and frequency sweep it. Measure the voltage response across it and the current through it. Use reactive power calculations to get your impedance curve. You can test it with a resistively loaded secondary or open secondary or a reactively loaded secondary.

Measuring something is one thing. The number you need determines how you measure it.
 
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