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Al Krow

Hybrid amps...the best of all worlds?

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[quote name='6v6' timestamp='1492760777' post='3282901']
folks sometimes run tubes at abnormally low voltages, and IMHO this is mostly a marketing strategy (folks see a glowing tube and are prepared to pay more),
[/quote]

This was my impression of most starved plate applications - it was a marketing exercise. But maybe that's not the case?

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[quote name='sratas' timestamp='1492758276' post='3282881'] Thanks passinwind, but I don't want to begin to study the matter. I would like to obtain simple answers. [/quote]

Don't feel alone, I'm still waiting for a simple answer naming any mainstream hybrid amps that use starved plate mode.

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[quote name='Passinwind' timestamp='1492763707' post='3282937']


Don't feel alone, I'm still waiting for a simple answer naming any mainstream hybrid amps that use starved plate mode.
[/quote]

I was under the impression that It was pretty much any AB / Class D head with a tube pre. I'm not saying I'm right, because I suspect you know different.

What's the facts?

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[quote name='wateroftyne' timestamp='1492764437' post='3282948']
I was under the impression that It was pretty much any AB / Class D head with a tube pre. I'm not saying I'm right, because I suspect you know different.

What's the facts?
[/quote]

I'll go out on a limb and guess that at least 90% of current production ones do not used starved plate mode.

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[quote name='Passinwind' timestamp='1492766399' post='3282973']
I'll go out on a limb and guess that at least 90% of current production ones do not used starved plate mode.
[/quote]

Interesting, thank you.

Do you think there could be any significant difference in the application of tubes in the pre of - say, the Walkabout or R-400 - to the likes of the Streamliner, etc.?

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Is there even a defined voltage for a 12ax7 that can be considered as starved plate or it can't be defined because it varies?

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[quote name='Passinwind' timestamp='1492766399' post='3282973']
I'll go out on a limb and guess that at least 90% of current production ones do not used starved plate mode.
[/quote]

That is my impression too, and I've been studying various guitar and bass amp schematics for years.

Admittedly there aren't that many hybrid bass amp schematics available, particularly for the newer class D stuff, but think about it from an amp designers point of view - what's easier, copy/paste one of a few classic and well understood tube preamp circuits and specify one extra winding on your transformer, or mess around trying to make a tube circuit sound good running tubes outside their normal operating range?

Unless you're running stuff on batteries it's a no-brainer IMO (yes, I'm an engineer, and yes I am lazy! :lol:)

The facts are out there in the schematics that are available, I've not found a any that show a mains powered amp running tubes at weirdly low "starved plate" voltages, but I'd be happy to study such a diagram if one exists.

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Wish I was able to interpret things like 6v6 or passinwind.

now I am curious about the tube specs of two amps I owned, namely the markbass lm tube and the genz streamliner

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[quote name='sratas' timestamp='1492768527' post='3283010']
Wish I was able to interpret things like 6v6 or passinwind.

now I am curious about the tube specs of two amps I owned, namely the markbass lm tube and the genz streamliner
[/quote]

I think it's extremely unlikely that a designer would build a bass amp with three tubes in it (like the SL) and use starved plate mode. Nothing I've heard when playing those amps makes me think they did either. I have very little experience with Markbass stuff, and have never looked inside one or seen a schematic for any of the hybrid ones. The best example I can think of offhand for a "trophy/marketing" tube implementation is the Carvin BX500, where the single tube comes after many solid state stages and doesn't even make any gain.

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It seems to be unlikely even to me...in effect...starved plate and marketing purposes seem to be quite rare, it seems.

This proves that a complex interaction of factors defines the result, and maybe talking about a single feature does not have much sense.

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[quote name='sratas' timestamp='1492798113' post='3283358']
This proves that a complex interaction of factors defines the result, and maybe talking about a single feature does not have much sense.
[/quote]

Yep, and although neither one of us may like it that much, "just depends" just may start to look like the most reasonable answer.

BTW, another reason that Andy and I might come off as sounding similar at times these days is because we both have to work under non-disclosure agreements, and giving away too many specifics is just bad business. When I was "just" a DIY'er I was probably a lot more informative, but so it goes.

Edited by Passinwind

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[quote name='Lozz196' timestamp='1492553872' post='3281249']
Those pre-amp valves in the GK MB Fusion make a lot of difference, in comparison to the regular MB 500. A lot more warmth and depth to the sound, making it able to sound very un-GK-like if desired. Not to say it doesn`t sound like a GK though, it does, just that the pre-amp valves give it a lot more flexibility than the regular MB 500 which is the typical GK sound through and through.
[/quote]

This was my experience too. I could theorise all day about this. I'm an electronics engineer of 40 years standing and have designed and built many solid state and valve amps outside of my day job. But when it came to getting a new lightweight head, I just spent a day at Bass Gear and picked the one that sounded best to me, having come from 30 years of SVT/Fridge. It was the MB Fusion 500 that I liked. It happened to have a valve preamp, not a factor in my choice at all though.

There was one sort of dogmatic issue. I'd really liked to have picked an amp with one volume control. Most bass players don't need to artificially overdrive their amps. We never had master volumes up until the '80s. The only amp which satisfied this was the Demeter. Too rich for my pocket though. Note to amp designers, an SVT stack isn't dirty. Quite the opposite.

And there's no such thing as starved plate, it's a starved anode.

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[quote name='tonewheels' timestamp='1492897335' post='3284039']
There was one sort of dogmatic issue. I'd really liked to have picked an amp with one volume control. Most bass players don't need to artificially overdrive their amps. We never had master volumes up until the '80s. The only amp which satisfied this was the Demeter. Too rich for my pocket though. Note to amp designers, an SVT stack isn't dirty. Quite the opposite.

[/quote]

I have a GK MB200 with a single volume control, and I reckon that a second volume control would be useful not so much for pushing the preamp into overdrive but for improving the signal/noise ratio when used at low volume. GK tend to voice their amps so that the highs are quite strongly boosted already with all of the EQ knobs at noon, and the preamp volume is early in the circuit, before the EQ. This does give them quite a lively character, but the extra gain in the highs can make them a bit more hissy than a flatter voiced amp would be. (Though I've not heard the Fusion 500 - maybe it's quieter than their op-amp preamps).

Edited by Beer of the Bass

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[quote name='Beer of the Bass' timestamp='1492897893' post='3284043']
I have a GK MB200 with a single volume control, and I reckon that a second volume control would be useful not so much for pushing the preamp into overdrive but for improving the signal/noise ratio when used at low volume. (Though I've not heard the Fusion 500 - maybe it's quieter than their op-amp preamps).
[/quote]

Yeh, I have an MB200 as a backup amp. It does satisfy the criterion of having a single volume control but the sound doesn't really work for me. Having said all that, I have a dream of an amp with just a switch and a volume control (to manage the noise threshold) and just running all the control off my USA Sterling bass which has all the EQ I'd ever need.

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[quote name='tonewheels' timestamp='1492899455' post='3284053']
Yeh, I have an MB200 as a backup amp. It does satisfy the criterion of having a single volume control but the sound doesn't really work for me. Having said all that, I have a dream of an amp with just a switch and a volume control (to manage the noise threshold) and just running all the control off my USA Sterling bass which has all the EQ I'd ever need.
[/quote]
Why not just buy a PA power amp. You might find one with a sensitivity high enough to drive direct or you could add a simple pre amp just to boost output an active DI might well give you enough. I have to say my best sound ever was using a simple PA amp with no tone controls, but that had mic level inputs.

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The only hybrid amp I've tried where I thought the 'valve preamp' was specially cool was the Genz Benz Streamliner... but it's hard to say whether the valve did anything meaningful. Any other amp, I just didn't see the point and certainly didn't approach the 'valve goodness' sound we all have in mind when thinking of valve amps.

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[quote name='Phil Starr' timestamp='1491926078' post='3276552']
There are good technical reasons why valve amps are popular, it's to do with the way they distort when overloaded mainly. It's a much nicer sound than that of an overloaded solid state amp. In turn that is to do with the nature of the whole output stage including the transformer you have to have with a valve output stage.[/quote]

The last valve amp I owned was a Mesa 400+ and that didn't do it for me on many levels. I also go back as far as the 60's where there were many valve amps that didn't sound good at all, so after years of using great sounding non-valve amps I'm not naturally a valve fan anymore. Undecided is the best I can offer on valve amps when compared to top quality SS and D class amps. I always run my amps clean. No overdrive or distortion in any part of the signal chain.

The conversation always seems to centre on what sounds better "overloaded". As I don't run amps like that I don't find a lot of relevance in these threads.

So does anyone have any insights into comparisons between non-valve amps and valve amps that are [i]not[/i] overloaded?

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I tend to agree with chris b.i had white valve amp in the late 70s which was virtually identical to orange .it was unreliable and overheated leading to excess distortion for my ears.i replaced it with an hh which i didnt like.along came trace and blew everything else out of the water for me.my amps are now over 30 yrs old and im looking for a new one.im also considering gk fusion or maybe a prodigy if modern valve amp design has improved.or does a d800+ fit the bill

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[quote name='zitherman' timestamp='1501238287' post='3343493']
...im also considering gk fusion or maybe a prodigy if modern valve amp design has improved.or does a d800+ fit the bill
[/quote]

Cripes - my head hurts! Just read this topic in a one-er while studying the combined Basschat 'knowledge' to help me find something modern/compact that floats my boat as much (though not necessarily in the same way) as the TE AH300 SMC GP7 I've been gigging for years. In another thread, I came across mcnach waxing lyrical about his D800+ - which is now on my shortlist (along with the Streamliner and Fusion for core sounds and RH750 for functionality). Oh, and maybe WoT's HandBox as well (should be able to play nicely with my Polish bass :D)! At risk of introducing another, off-topic, variable, the fact that mcnach is running his D800+ thru my beloved BF Two 10 cab's is of special interest to me.

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Guest bassman7755

[quote name='scrumpymike' timestamp='1501239901' post='3343504']
Cripes - my head hurts! Just read this topic in a one-er while studying the combined Basschat 'knowledge' to help me find something modern/compact that floats my boat as much (though not necessarily in the same way) as the TE AH300 SMC GP7 I've been gigging for years. In another thread, I came across mcnach waxing lyrical about his D800+ - which is now on my shortlist (along with the Streamliner and Fusion for core sounds and RH750 for functionality). Oh, and maybe WoT's HandBox as well (should be able to play nicely with my Polish bass :D)! At risk of introducing another, off-topic, variable, the fact that mcnach is running his D800+ thru my beloved BF Two 10 cab's is of special interest to me.
[/quote]

I think the takeway summary is that having an actual valve in the [b]preamp [/b]part of an amp makes no odds and wont make it sound any more "valvey" than and all-SS amp with a well designed drive circuit.

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[quote name='bassman7755' timestamp='1501285758' post='3343874']
I think the takeway summary is that having an actual valve in the [b]preamp [/b]part of an amp makes no odds and wont make it sound any more "valvey" than and all-SS amp with a well designed drive circuit.
[/quote]

I think that is a fair summary. And e.g. the Genzler Magellan is getting a lot of praise for its well designed circuitry in this regard.

However, the one "fly in the ointment" in the statement is the Two Notes Le Bass pedal. Cuzzie recently recorded some excellent samples with his Two Notes Le Bass preamp in clean and then with various combinations of dials engaged. It came as close to a realistic warm valve sound as I've heard from a non valve power amp (90%+ of the way there of the way there ). Not sure that there are too many SS circuits that give the Two Notes a run for its money? SS circuits can maybe get to (say) 80% and the question then is, is 80% emulation enough? It probably is for live performance (as opposed to studio recording) as, let's be honest, neither bandmates nor audience in a live band mix are going to notice the remaining 20% of the pass players' marginal change in tone.

Edited by Al Krow

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[quote name='bassman7755' timestamp='1501285758' post='3343874']
I think the takeway summary is that having an actual valve in the [b]preamp [/b]part of an amp makes no odds and wont make it sound any more "valvey" than and all-SS amp with a well designed drive circuit.
[/quote]

My HandBox R-400 sounds beautiful - like, really beautiful - not like any head I've owned before. I wonder what it would sound like entirely SS?

My guess is as they've gone to the effort of shoe-horning three valves into it, it's having some effect on the tone.

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[quote name='chris_b' timestamp='1501234148' post='3343440']

So does anyone have any insights into comparisons between non-valve amps and valve amps that are [i]not[/i] overloaded?
[/quote]

No insights, just an opinion. I use my amps clean to the point where the signal 'just' starts to break up a little - warm but not remotely overdriven. Over the last 10 years or so I have used all sorts - class D, class D with tube pre, AB. Off the top of my head TC Electronic RH750, Harley Benton 500 (so Ibanez Prometheon, Red Sub), - Eden forget which, GB Streamliner, Mark Bass Little Mark Tube 800, whichever Mark Bass is in the combos, Fender Rumble 500, Orange TB500. Quilter Bassblock 800, Ashdown ABM500, Trace Elliot AH300. Trace Elliot heads always gave me the tone of choice. Orange is a close second followed by Quilter.

Then very recently I acquired a Mesa Boogie Prodigy Four:88 and I can honestly say it is leagues above all the others. There is an organic, extra-dimensional quality about the tone way above those with tube preamps. I don't have the words to describe it properly but it puts a smile on my face whenever I have used it so far. Band mates have said it is by far the best sound I have had, so I guess it does notice.

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[quote name='wateroftyne' timestamp='1501312587' post='3343918']
My HandBox R-400 sounds beautiful - like, really beautiful - not like any head I've owned before. I wonder what it would sound like entirely SS? My guess is as they've gone to the effort of shoe-horning three valves into it, it's having some effect on the tone.
[/quote]

[quote name='Paul S' timestamp='1501315582' post='3343935']
Then very recently I acquired a Mesa Boogie Prodigy Four:88 and I can honestly say it is leagues above all the others. There is an organic, extra-dimensional quality about the tone way above those with tube preamps. I don't have the words to describe it properly but it puts a smile on my face whenever I have used it so far. Band mates have said it is by far the best sound I have had, so I guess it does notice.
[/quote]

Paul I would love to hear the Four:88 in action. It does sound wonderful (if not a little pricey!) Three Qs if I may - did you get from a UK supplier, what cabs are your pairing it with and at 250W does it give you all the headroom you need?

The Handbox seems also to be another much loved (certainly by WoT :)) and affordable "solution" and [u]three[/u] valves in the preamp ain't going to just sit there looking pretty and just do nothing! (I know that a single valve in my Mesa M6 provides a lot of warmth).

Be great to hear them both

Edited by Al Krow

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[quote name='Al Krow' timestamp='1501316578' post='3343946']
The Handbox seems also to be another much loved (certainly by WoT :)) and affordable "solution" and [u]three[/u] valves in the preamp ain't going to just sit there looking pretty and just do nothing!
[/quote]

Yeah.. I'm aware I keep banging on about the HandBox like a stuck record, but it's actually frustrating that an amp like this exists with such a low profile. It deserves to be massive, so I'm just going to shout it from the rooftops :-)

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