Thunderbird Club

[PillO]

As I'm sure I've said before I'd be up for a Marshal 2099 100W head. Dunno what's going on with them that they have a 8Ω/4Ω switch on the back. Well you can see what's going on but the question is why?

View attachment 1557643

Marshall's, sometimes, instead of having different output jacks for 4Ω and 8Ω they just have a switch.

But it's a solid state amp ... then you look at the schematic.

It's a solid state amp ... with an output transformer ... er w.t.f??

My electronics goes back to high school and that was a long time ago...

But here goes:
On the output stage, that is not a transformer but an induction coil. It operates the same way that the ignition coil in a car does. It offers changes in voltage and current (in this case output impedance) without electrical isolation. So, whereas the coil in a car is used to increase voltage to produce a spark at the spark plug, this one is to ensure that you have your full 100W available for loads of 4-16 ohms by matching output impedance to the speaker load.

 

[Gaolee]

As I'm sure I've said before I'd be up for a Marshal 2099 100W head. Dunno what's going on with them that they have a 8Ω/4Ω switch on the back. Well you can see what's going on but the question is why?

View attachment 1557643

Because they can. I can't imagine what it would do, though. Add a resistor so that it's always 100 watts? If you didn't hit the switch, it would be 200 watts through 4 ohms perhaps? Or...

 

[kat888]

Honestly I didn't look at the schematic first. But would help if they had a model number because I only know of 2 bass series made by Marshall, the all tube Amps out of the 70's era (Think Lemmy), and the MB series out of the late 2000's early 2010's (years may be off but you get the point). I have an MB150 combo and it's a hybrid amp. I think they made just a head as well but I think it's a 400 Watt. Only reason I think it's a amp head is because the various Ohm settings instead of a set resistance.

Unless they made another bass amp that I'm missing and someone else knows about.

The 2099 was released in 1975 and was Marshall's first solid state amp. I played through one once and it was the best silicon based amp I'd ever heard. Really warm sounding - maybe something to do with the output arrangements -- ie the induction coil (thanks @PillO).

 

[Gaolee]

But it's a solid state amp ... then you look at the schematic.

It's a solid state amp ... with an output transformer ... er w.t.f??

My little BR-9 guitar amp is a tube amp, but it's got no output transformer, either. You have to put one in if you want to swap out the speaker, since it's a field coil speaker. The Marshall probably has an output coil or something similar.

Or because they can. That's all I can think of. I know absolutely nothing useful about electronics except how to wire a guitar and damage amplifiers.

Ah, Phil already explained it, and actually knows something. Never mind.

 

[Dr_Feelgoood212]

The 2099 was released in 1975 and was Marshall's first solid state amp. I played through on once and it was the best silicon based amp I'd ever heard. Really warm sounding - maybe something to do with the output arrangements -- ie the induction coil (thanks @PillO).

View attachment 1560410

OHH never heard of them before. Very interesting, time to spend a lot of time looking into it
My Marshall combo I bought when I was 11ish, and only because it said Marshall on it, but comparing to other amps now, it seems fairly dull. Probably why you don't see many of the MB series around.

 

[Gaolee]

Try it out on some scrap lumber first, so you can fine tune it how ya want...

Way too logical and reasonable. I don't do stuff like that. Crawl first? Heck no! Learn to run before even knowing how to stand up without falling down. There's no way to fight history and personality defect.

 

[PillO]

Because they can. I can't imagine what it would do, though. Add a resistor so that it's always 100 watts? If you didn't hit the switch, it would be 200 watts through 4 ohms perhaps? Or...

The other way around - if you didn't flip the switch, you would get 50W on your 8 ohm load or 25W on 16 ohms

 

[theFixer]

Way too logical and reasonable. I don't do stuff like that. Crawl first? Heck no! Learn to run before even knowing how to stand up without falling down. There's no way to fight history and personality defect.

It's my job to drop 'em out there... it's your job to pick 'em up or walk on by. Either is acceptable

 

[PillO]

The 2099 was released in 1975 and was Marshall's first solid state amp. I played through on once and it was the best silicon based amp I'd ever heard. Really warm sounding - maybe something to do with the output arrangements -- ie the induction coil (thanks @PillO).

View attachment 1560410

I could attribute the warmth to the output transformer and the use of a field effect transistor*. But my knowledge here is very rusty, in looking at the circuit, I could discern the gain, treble and bass, master volume, but couldn't find anything else. It is a balanced push-pull amp if that is of any value?

*Field effect transistors are much more tube like in their performance. MOS-FETs even more so.

 

[kat888]

OHH never heard of them before. Very interesting, time to spend a lot of time looking into it
My Marshall combo I bought when I was 11ish, and only because it said Marshall on it, but comparing to other amps now, it seems fairly dull. Probably why you don't see many of the MB series around.

They're not 'collectible'. There was one on Reverb for less than $AUD200 but was gone before I saw it. The stock ICs are 741s, so you'd want to replace those. 3 inputs -- 1, 2 and 1+2 (ie 'jumpered'), 2 channel gains, master volume and standard B M T P tone controls.

 

[kat888]

I could attribute the warmth to the output transformer and the use of a field effect transistor*. But my knowledge here is very rusty, in looking at the circuit, I could discern the gain, treble and bass, master volume, but couldn't find anything else. It is a balanced push-pull amp if that is of any value?

*Field effect transistors are much more tube like in their performance. MOS-FETs even more so.

Yeah, back when I had occasion to play through that Marshall, I had a hybrid valve/MOSFET amp, so I'm familiar with their properties.

I know I've posted it before, but the amp was actually the 2099 in this video.

 

[kat888]

^^^this^^^

If you refer to them as "valves" around here... the listener is first confused & has no idea what you're talking about, then moves on to thinking you'e a snooty pretentious a-hole when he/she figures out yer talking' about "tubes".

As the man said, I'll stand my ground/And I won't back down.

SVT = 'Super Valve Technology', referring to the the use of thermionic valves. They were and remain valves. A tube is something you keep toothpaste in ... or @ProgressiveDoom keeps his balls in*.

PS. I make it my business to confuse Americans, seeing as the rest of us have no idea what youse are talking about half the time, it's only fair and reasonable to return the favour.

* and I still have one shot left.

 

[JIO]

I could attribute the warmth to the output transformer and the use of a field effect transistor*. But my knowledge here is very rusty, in looking at the circuit, I could discern the gain, treble and bass, master volume, but couldn't find anything else. It is a balanced push-pull amp if that is of any value?

*Field effect transistors are much more tube like in their performance. MOS-FETs even more so.

like my Mesa Basis M-2000

 

[Dr_Feelgoood212]

As the man said, I'll stand my ground/And I won't back down.

SVT = 'Super Valve Technology', referring to the the use of thermionic valves. They were and remain valves. A tube is something you keep toothpaste in ... or @ProgressiveDoom keeps his balls in*.

PS. I make it my business to confuse Americans, seeing as the rest of us have no idea what youse are talking about half the time, it's only fair and reasonable to return the favour.

* and I still have one shot left.

Wudda they call 'em in Canada... tubes or valves?

I have heard them be referred to as Valves often enough that I wasn't confused.... this time

 

[kat888]

like my Mesa Basis M-2000View attachment 1567512

Now that is an interesting looking amp. In your face class D!

 

[GBassNorth]

Tubes, vacuum tubes, valves, solid state, hybrid, mos-fet, boba-fett ... whatever it takes to make my bird low and loud works for me!

 

[RedVee]

my 2006 definitely has a slim profile. Wide, but slim.

Yep, same - and mine has a angled head as well.

 

[RedVee]

try it this way? Still works for me

Not available to me.

 

[GBassNorth]

Not available to me.

Red - that was so three pages ago! LOL - staying on top of this thread is a full time job. Fixer found out that it works on the computer but gets iffy on mobile devices like my iPad and iPhone. Later this evening I'll breakdown and give it a try on my Mac.

 

[hillerup]

I wasn't aware you weren't a fan. I'll make sure to include you in the next warning

It's the voice, man... As soon as I hear Geddy's voice I turn the music off.