Swapping out preamp valves?

[Greco]

Hi,

I've heard of at least one person swapping out the preamp valves in their VM for NOS tubes.

I'm a total bubble-head when it comes to amps so go easy on me. I've always been put off shelling out for expensive amps that didn't have the features I wanted - Now I've found all these features in the VM.

The spec for the 2466 says it has 4x ECC83 in the preamp. To me it looks like my VM has 2x glass ECC83's and then two metal covered things. Are these all ECC83's or what? (obviously I know which ones are the KT66s!)

I haven't really taken it apart to have a closer inspection yet but...Assuming I could get hold of some NOS tubes, would I need a matched quad or two matched pairs, or am I just crazy?

Are the metal covered ones ECC83's just with some weird casing and if so what is the purpose of the metal casing?

Thanks for any light you can shine into my cavernous void of a brain.


Cheers¬!

[Greco]

Hey thanks. that makes sense.

So anyone know if I need 2 matched pairs?

[SteveD]

All preamp valves are indeed ECC83s and V1 and V2 are shielded to prevent noise issues due to their proximity to emissions from the output transformer; they are both sensitive stages and the signal level here is very susceptible to interference (which will also be amplified!).

You do not have to match preamp valves but you can select them in listening tests if you're that way inclined; they do vary in terms of microphony and to a lesser degree gain.

If you want to put NOS preamp valves in then that is your choice but I would make sure that they are worth the expense to your ears.

Steve

[Scruffy Red Dog]

You can mix and match pre-amp valves so you might want to get one NOS valve and try it in V1 first to see if you can hear a noticable improvement.

[SteveD]

OK guys here is the lowdown; -

V1 is the first gain stage included in the signal path on both dynamic ranges.

V2 is an extra gain stage which is included only on the high dynamic range.

V3 is the tone stack

V4 is the phase inverter.

If anybody requires any clarification of what the various pots and switches do on the Vintage Modern I would be happy to explain in detail; just give me a shout.

Steve

[SteveD]

......and an invite to Jim Marshall's birthday party at the end of July. LOL!

Seriously though, it seems apparent that there are many people out there who are approaching the Vintage Modern from the wrong angle and I would be happy to help those who need a little 'old school' education.

How about a technical info sticky thread for people to reference when they visit the board.

Steve

[Scruffy Red Dog]

How about a technical info sticky thread for people to reference when they visit the board.

Yeah, you could put that ohms chart in so I can't screw it up and start confusing people all over again. :lol:

[antosimoni]

OK guys here is the lowdown; -

V1 is the first gain stage included in the signal path on both dynamic ranges.

V2 is an extra gain stage which is included only on the high dynamic range.

V3 is the tone stack

V4 is the phase inverter.

If anybody requires any clarification of what the various pots and switches do on the Vintage Modern I would be happy to explain in detail; just give me a shout.

Steve

hi Steve,
thanks for your attention, please take a time to answer these simple questions :

so the Fx Loop and the Reverb are not tube-driven ?

why the Detail control is much more gainier than the Body one?

the mid-boost is not tube-driven, right?

and.... could you please suggest me the best settings to nail JTM (or Plexi) tones? I'm having a hard time with that...

thanks a lot for your patience :D and for your great job

[SteveD]

OK guys here is the lowdown; -

V1 is the first gain stage included in the signal path on both dynamic ranges.

V2 is an extra gain stage which is included only on the high dynamic range.

V3 is the tone stack

V4 is the phase inverter.

If anybody requires any clarification of what the various pots and switches do on the Vintage Modern I would be happy to explain in detail; just give me a shout.

Steve

hi Steve,
thanks for your attention, please take a time to answer these simple questions :

so the Fx Loop and the Reverb are not tube-driven ?

why the Detail control is much more gainier than the Body one?

the mid-boost is not tube-driven, right?

and.... could you please suggest me the best settings to nail JTM (or Plexi) tones? I'm having a hard time with that...

The FX loop utilises high voltage mosfets which behave in a similar way to valves. The FX loop stages are only conditioning buffers and I wasn't after any distortion from these stages so it works very well IMO. What do you think?

I didn't see the point in driving a digital reverb with a valve.

The Detail and Body controls both have the same gain. The 'Detail' controls gain from 400Hz upward and the Body controls gain from 400Hz downward. Virtually all of a guitar's harmonic distortion can be found in the Detail control's area so it is this control which has the most dramatic affect. The Body control affects the fundamental frequencies. There is a natural classic Marshall mid dip at 400Hz (the crossover frequency) which can be boosted and flattened out with the mid boost button if you like. The mid boost is a passive circuit in the signal path, not an extra stage.

The Vintage Modern is basically a JTM45 with some hot rodding. For a JTM 45 tone select the low dynamic range, master volume on full, mid boost out, Detail at 2 -4 o'clock. Body at 1 - 3 o'clock and then dime the tones. This should be very close.

The vintage Modern is essentially a Plexi with some bells and whistles. Its foundation is the 'JTM 45 Super 100's' as championed by Hendrix, Clapton in Cream and several others.

[antosimoni]

The FX loop utilises high voltage mosfets which behave in a similar way to valves. The FX loop stages are only conditioning buffers and I wasn't after any distortion from these stages so it works very well IMO. What do you think?

I didn't see the point in driving a digital reverb with a valve.

The Detail and Body controls both have the same gain. The 'Detail' controls gain from 400Hz upward and the Body controls gain from 400Hz downward. Virtually all of a guitar's harmonic distortion can be found in the Detail control's area so it is this control which has the most dramatic affect. The Body control affects the fundamental frequencies. There is a natural classic Marshall mid dip at 400Hz (the crossover frequency) which can be boosted and flattened out with the mid boost button if you like. The mid boost is a passive circuit in the signal path, not an extra stage.

The Vintage Modern is basically a JTM45 with some hot rodding. For a JTM 45 tone select the low dynamic range, master volume on full, mid boost out, Detail at 2 -4 o'clock. Body at 1 - 3 o'clock and then dime the tones. This should be very close.

The vintage Modern is essentially a Plexi with some bells and whistles. Its foundation is the 'JTM 45 Super 100's' as championed by Hendrix, Clapton in Cream and several others.

wow :D
thanks Steve,
yes the loop works well it does its job perfectly : I use only delays in loops and nothing else but for me it works good,
the JVM reverb is digital & driven by a tube if I recall correctly the diagram on the last page of the manual (I own a JVM also) so I was guessin' that the VM one is similar, thats why I've asked you,
and another big thank you for the explanation about the 2 preamp controls now things are much more clear for me, cant wait to get home, I'll immediately check your suggestions and post my impressions

[antosimoni]

Steve and all,
to dont go OT too far I've started another topic about the above, its there

http://vintagemodern.informe.com/viewtopic.php?t=58

[OdgeUK]

The Vintage Modern is basically a JTM45 with some hot rodding.

The vintage Modern is essentially a Plexi with some bells and whistles. Its foundation is the 'JTM 45 Super 100's' as championed by Hendrix, Clapton in Cream and several others.

SteveD, that is almost EXACTLY what I've been waiting for from Marshall. Nearly. How about now you do an early 70's Metalface 50W with a PPIMV. Get that EL34 thing going on with the Vintage Modern concept applied?

I see in a previous post you have a '73 JMP, so there must be some 'love' for that sound? How about it? :lol: :lol:

[SteveD]

The Vintage Modern is basically a JTM45 with some hot rodding.

The vintage Modern is essentially a Plexi with some bells and whistles. Its foundation is the 'JTM 45 Super 100's' as championed by Hendrix, Clapton in Cream and several others.

SteveD, that is almost EXACTLY what I've been waiting for from Marshall. Nearly. How about now you do an early 70's Metalface 50W with a PPIMV. Get that EL34 thing going on with the Vintage Modern concept applied?

I see in a previous post you have a '73 JMP, so there must be some 'love' for that sound? How about it? :lol: :lol:

One of the main reasons I wanted to do the Vintage Modern was because Marshall had never released a hot rod version of the early JTM amps which used KT66s and had a different tone. :shock: Just about every amp that Marshall has released in the last 30 years has evolved from the EL34 topology. The Vintage Modern is a sort of a missing link that previously only artists who'd had their early amps modified had. :x

I do love my 1973 50W very much :D

Who knows what the future will bring but personally I think the JVM has the EL34 thing pretty well covered.

[OdgeUK]

Thanks Steve. Fair point :) I'm a little biased because the Metalface JMP sound is my absolute favourite tone ever 8) and the only real way to get the sound is to buy an original (although I've not played the JVM).

I think it's great that the VM has that KT66 character. It still sounds blatantly 'Marshall' to those familiar with the decades of EL34 amps, but with a little something else in it's tone. Because of the different voicing, it's going to be a real great amp for players who want to take the Marshall sound forward without sounding too generic.

In fact, the first guy who records a hugley successful record using a VM will probably forever be associated with that KT66-on-steroids tone, and millions of people will rush out to buy a VM to replicate it, and the huge cheques will come rolling in and you'll be able to retire in the country with 8 cars on the drive and a special 'Plexi' room in the basement. :lol: :lol:

Once again, nice job. I can't wait to get one.

[SteveD]

Damn!!