Valve power amps

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digitalscreamdigitalscream Frets: 14230
I find myself desiring a mono 40W+ valve power amp, preferably 1U and not too heavy (or pricey). Does such a thing exist?

I know there's the Marshall 20/20, but it's stereo. I can live with that if need be, but I'd much rather have a straight mono amp (the 20/20 can't be bridged). The Deep switch is a definite bonus, mind.

There's also the R&R SOLO (of which I believe there's one in the country which used to be mine), but that fails on the price front mainly because it's a full-on two-channel amp.

Anything else?
"Mains is ouchy if you get it up you" - Sporky
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  • Danny1969Danny1969 Frets: 3900
    edited April 2014

    I used to use the 20/20 ... it's a sweet little amp but has some problems. Air intake is from the side and in a regular rack it can overheat. At least mine did till I modded the rack. It's also not the loudest of amps either, it was enough for me but you could run into problems in certain situations

    Almost all the rack power amps are stereo because their designed for stereo effects, I've never seen a mono one. I use the EL34 100/100 now and enjoy the duel mono block redundancy. Only last month a valve went at a gig, so I just turned that side off and used the other. Downside is weight, it's stupidly heavy so lives in a rack on wheels. 

    What about tearing the guts out of a 40 watt combo, junking the pre stages and just keep the power section. You could get a 2U rack case and make it quite easy using turret strips and bolting the mains and speaker transformers to the rack chassis. That would be a nice little project :)
    www.2020studios.co.uk 
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  • octatonicoctatonic Frets: 21422
    You will struggle to find a low wattage monobloc.

    Fryette have been threatening to release the LXII which could be 40w stereo or 80w mono but it never happened.
    Really you should look for a stereo amp that has independent standby for each channel and run one side at a time.

    I did this with the VHT2:50:2 before I went for the Matrix and it worked fine.
    I would avoid the Marshall 20/20 for the reasons Danny states.

    I find pretty much all the 20watter power amps to be underpowered in terms of clean headroom.
    Any of the 50 watt ones should be fine- the VHT/Fryette is really terrific.

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  • digitalscreamdigitalscream Frets: 14230
    Danny1969 said:

    I used to use the 20/20 ... it's a sweet little amp but has some problems. Air intake is from the side and in a regular rack it can overheat. At least mine did till I modded the rack. It's also not the loudest of amps either, it was enough for me but you could run into problems in certain situations

    Almost all the rack power amps are stereo because their designed for stereo effects, I've never seen a mono one. I use the EL34 100/100 now and enjoy the duel mono block redundancy. Only last month a valve went at a gig, so I just turned that side off and used the other. Downside is weight, it's stupidly heavy so lives in a rack on wheels. 

    What about tearing the guts out of a 40 watt combo, junking the pre stages and just keep the power section. You could get a 2U rack case and make it quite easy using turret strips and bolting the mains and speaker transformers to the rack chassis. That would be a nice little project :)
    Yeah...I figured the 20/20 would be fine using it stereo (with a mono input), because it's basically a 40W amp (I play with a 50 watter which, with its current valves, only puts out about 42W anyway). Wasn't aware of the intake issue, though...that's a bit of PITA.

    You're right that it'd make a nice little DIY project to convert a head or combo into a power amp, but I'm not sure I'm technically up to the job.

    I might just go for an ART SLA-1...I just love the idea of the Deep switch on the Marshall. Reliability and (lack of) weight of a solid state amp would be nice, mind.

    There's also the 2U Peavey Classic 50/50. It isn't dual monobloc, but it can run mono (100W) and has resonance controls on each channel. The only downside is weight - 13kg, twice the Marshall. I did have a 60/60 once, and it was bloody brilliant...even heavier, though, and 3U.

    octatonic said:
    You will struggle to find a low wattage monobloc.

    Fryette have been threatening to release the LXII which could be 40w stereo or 80w mono but it never happened.
    Really you should look for a stereo amp that has independent standby for each channel and run one side at a time.

    I did this with the VHT2:50:2 before I went for the Matrix and it worked fine.
    I would avoid the Marshall 20/20 for the reasons Danny states.

    I find pretty much all the 20watter power amps to be underpowered in terms of clean headroom.
    Any of the 50 watt ones should be fine- the VHT/Fryette is really terrific.
    Yeah, I've been looking at those...price is a bit out of my range, though. £300 is essentially the top end of what I can reasonably spend.
    "Mains is ouchy if you get it up you" - Sporky
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  • ecc83ecc83 Frets: 939

    Y'know, I tried to to tell 'em a couple of times that a rack mount amp would sell!

    You can connect two stereo amp channels in parallel and get twice the power into 1/2 the Z . Quad lls were often used this way for "HI-Fi" PA work.

    Dave.

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  • octatonicoctatonic Frets: 21422
    If you're looking at the ART why not consider the Matrix?
    It is much, much better.

    £300 is a tricky price point.
    You could get a Mesa 5050 for a bit more than that but if you are prepared to spend extra for the Mesa 5050 then you might as well go the whole hog for the VHT/Fryette.

    The Peavey is good for the money.

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  • digitalscreamdigitalscream Frets: 14230
    ecc83 said:

    Y'know, I tried to to tell 'em a couple of times that a rack mount amp would sell!

    You can connect two stereo amp channels in parallel and get twice the power into 1/2 the Z . Quad lls were often used this way for "HI-Fi" PA work.

    Dave.

    Funnily enough, a rack amp is consistently the most popular request for the Jet City boys. They're convinced that they won't sell.

    I'm a bit squicky about connecting power outputs together, for some reason...
    "Mains is ouchy if you get it up you" - Sporky
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  • digitalscreamdigitalscream Frets: 14230
    octatonic said:
    If you're looking at the ART why not consider the Matrix?
    It is much, much better.

    £300 is a tricky price point.
    You could get a Mesa 5050 for a bit more than that but if you are prepared to spend extra for the Mesa 5050 then you might as well go the whole hog for the VHT/Fryette.

    The Peavey is good for the money.
    It's all about the price, really. Can't find any Matrix amps for that money (not even the old XT500). The ART is about £230 new, which helps...
    "Mains is ouchy if you get it up you" - Sporky
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  • digitalscreamdigitalscream Frets: 14230
    edited April 2014
    Hang on a sec...am I thinking about this completely wrong? What about a bass amp, like the Peavey Tour 450? Built-in EQ, plenty of headroom and designed to be clean all the way to the top. The only worry is that the top end might be lacking.
    "Mains is ouchy if you get it up you" - Sporky
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  • octatonicoctatonic Frets: 21422
    edited April 2014
    Hang on a sec...am I thinking about this completely wrong? What about a bass amp, like the Peavey Tour 450? Built-in EQ, plenty of headroom and designed to be clean all the way to the top. The only worry is that the top end might be lacking.
    Plenty of bands have used bass amps as guitar amps.
    Yes you will have some EQ correction to do.
    What preamp will you be using?

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  • vizviz Frets: 5480
    Carvin do a whole range of 2u amps - not sure if they have one stepped to 240 though.
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  • citizen68citizen68 Frets: 170
    Maybe a silly question but why are the valve power amps seemingly much more expensive than for example a decent valve guitar amp?
    Seemed like a good idea.....

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  • Phil_aka_PipPhil_aka_Pip Frets: 9765
    May I suggest its because it takes more design effort and better quality components to get one to run clean at the rated o/p, whereas a guitar amp can distort like hell and have a narrow bandwidth?
    "Working" software has only unobserved bugs. (Parroty Error: Pieces of Nine! Pieces of Nine!)
    Seriously: If you value it, take/fetch it yourself
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  • octatonicoctatonic Frets: 21422
    citizen68 said:
    Maybe a silly question but why are the valve power amps seemingly much more expensive than for example a decent valve guitar amp?
    There isn't a huge difference if you compare like for like.
    If you compare a stereo power amp to the price of a professional high end amplifier then they are roughly equivalent.
    Power amps are generally built to a high spec, have two output transformers, one per channel, too.
    They are sold in much smaller numbers, which must account for some of the difference.

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  • fretmeisterfretmeister Frets: 10922
    Hang on a sec...am I thinking about this completely wrong? What about a bass amp, like the Peavey Tour 450? Built-in EQ, plenty of headroom and designed to be clean all the way to the top. The only worry is that the top end might be lacking.

    So use a PA amp. Most big bass power amps are really PA amps anyway.

    I used a Yamaha P5000S for ages and it was brilliant - both with bass preamps and a Line 6 Pod Pro.

    Hello darkness my old friend.


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  • Danny1969Danny1969 Frets: 3900

    In terms of design you don't need any great bandwidth for guitar, there's very little going on under 80hz or so and not much above 6K . The cost of stereo power amps is a lot because of the increased component count, basically it's 2 amps in one box even if it's not a duel monoblock design and they are made in much smaller numbers. 

    I always felt gigging a modeller into solid state amps was a bit harsh. I used a Rotel amp, a Marshall Valvestate and a homebrew amp I built. I wasn't happy until I spent the money on a valve power amp ..... there's something about the ouput transformer in a valve design that filters off the nasties and harshness. I've often wondered if an SS amp might benefit from a transformer on the output stage even though it doesn't need one. A simple 1:10 and 10:1 back again, not to change any transfer impendence but to benifit from the effects of passing an audio signal through a transformer. That's where some of the mojo is in my opinion, it's not just the valves but the transformers. 
    www.2020studios.co.uk 
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  • ecc83ecc83 Frets: 939
    edited April 2014
    Once you have the power and output transformers and a chassis to take them there is not a great deal left in a guitar amplifier. Ok! Yes SOME are very complex but even so most of the cost is in the mass.

    A valve power amp would typically consist of a pair of OP valves, a PI and maybe another double triode input amp. However there is unlikely to be much of a market for a GUITAR specc' power amp with its low quality (in "hi-fi" terms) output traff, high output impedance, soggy PSU and high distortion (again, ref say a Quad or Radford) .

    No, I would like to see a rack version of the HT-5 for studio use. The ID series are of course naturals for racking...But nobody listens to me!

    Danny. Don't get TOO hung up on transformers. Valves, especially pre amp valves have a far bigger tonal effect. In any case, by definition, traffs only make a difference if you drive the bllx off them and most often you can't for social reasons (in fact it is virtually impossible to "saturate" a guitar amp OPT)
    Dave.
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  • digitalscreamdigitalscream Frets: 14230
    So use a PA amp. Most big bass power amps are really PA amps anyway.

    I used a Yamaha P5000S for ages and it was brilliant - both with bass preamps and a Line 6 Pod Pro.
    That's part of my logic, actually - the difference is that a bass amp like the Peavey Tour 450 also has some tone-shaping capability (resonance and a 9-band EQ) which could come in handy.
    "Mains is ouchy if you get it up you" - Sporky
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  • siraxemansiraxeman Frets: 1925
    i'm a simpleton i'd just have a rack with preamp n fx and get a nice head and feed all that into the loop..i see many pro players with 2 or 3 heads racked up like that i guess thats what they are doing also??
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  • digitalscreamdigitalscream Frets: 14230
    siraxeman said:
    i'm a simpleton i'd just have a rack with preamp n fx and get a nice head and feed all that into the loop..i see many pro players with 2 or 3 heads racked up like that i guess thats what they are doing also??
    Yup - I can attest to the fact that the Eleven sounds awesome into the loop of my Jet City 50W (probably helped by the fact that the loop is in front of the tone stack). Thing is, I don't particularly want my rig to get bigger and heavier...smaller and lighter is the order of the day ;)
    "Mains is ouchy if you get it up you" - Sporky
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  • ChrisMusicChrisMusic Frets: 1118
    Just to turn the thumb screws up a bit ~ this is available second hand at Coda in Stevenage ~ right now
    I know it is over budget, but as they say where there is a will there is a way, so here goes...

    Mesa Boogie 5050 Power Amp £599


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  • dindudedindude Frets: 6299
    Rocktron also do the velocity 100 for the same sort of price as the Art.
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  • Danny1969;211192" said:
    In terms of design you don't need any great bandwidth for guitar, there's very little going on under 80hz or so and not much above 6K . The cost of stereo power amps is a lot because of the increased component count, basically it's 2 amps in one box even if it's not a duel monoblock design and they are made in much smaller numbers. 

    I always felt gigging a modeller into solid state amps was a bit harsh. I used a Rotel amp, a Marshall Valvestate and a homebrew amp I built. I wasn't happy until I spent the money on a valve power amp ..... there's something about the ouput transformer in a valve design that filters off the nasties and harshness. I've often wondered if an SS amp might benefit from a transformer on the output stage even though it doesn't need one. A simple 1:10 and 10:1 back again, not to change any transfer impendence but to benifit from the effects of passing an audio signal through a transformer. That's where some of the mojo is in my opinion, it's not just the valves but the transformers. 
    A bandit has a transformer. I don't know tech specs, but the one in mine looks like something in a valve amp.

    I used to love seeing the toroidal bitch in my old Laney.
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  • jpfampsjpfamps Frets: 1692
    I find myself desiring a mono 40W+ valve power amp, preferably 1U and not too heavy (or pricey). Does such a thing exist?

    I know there's the Marshall 20/20, but it's stereo. I can live with that if need be, but I'd much rather have a straight mono amp (the 20/20 can't be bridged). The Deep switch is a definite bonus, mind.

    There's also the R&R SOLO (of which I believe there's one in the country which used to be mine), but that fails on the price front mainly because it's a full-on two-channel amp.

    Anything else?
    A 1U 40W power amp will be a tight squeeze, and probably not that sensible from a thermal management point of view.

    Also unless you use two output transformers then you won't get a 40W EI laminated output transformer in 1U. There are now some toroidal output transformers available which may fit, but these are generally expensive.


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  • jpfampsjpfamps Frets: 1692
    Danny1969 said:

    In terms of design you don't need any great bandwidth for guitar, there's very little going on under 80hz or so and not much above 6K . The cost of stereo power amps is a lot because of the increased component count, basically it's 2 amps in one box even if it's not a duel monoblock design and they are made in much smaller numbers. 

    I always felt gigging a modeller into solid state amps was a bit harsh. I used a Rotel amp, a Marshall Valvestate and a homebrew amp I built. I wasn't happy until I spent the money on a valve power amp ..... there's something about the ouput transformer in a valve design that filters off the nasties and harshness. I've often wondered if an SS amp might benefit from a transformer on the output stage even though it doesn't need one. A simple 1:10 and 10:1 back again, not to change any transfer impendence but to benifit from the effects of passing an audio signal through a transformer. That's where some of the mojo is in my opinion, it's not just the valves but the transformers. 

    I would agree that the output stage of a valve is what gives it the "valve" sound; hybrid amps with SS pre-amps and valve output stages (eg the 70s Musicman amps), sound like valve amps to me, whereas the converse don't.

    Some of the very early transistor guitar amps had output transformers (and even interstage transformers), although they didn't generally sound great.

    Dave Peterson developed a SS amp with a transformer in it to help emulate a valve amp (I think they were called RIF amps). Not sure if they made it into production.

    Extending HF bandwidth in a output transformer over and above the audio bandwidth is important if you are using negative feedback to avoid ringing, or worse oscillation. In my experience this is a real phenomenon in valve guitar amps.
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  • digitalscreamdigitalscream Frets: 14230
    jpfamps said:
    A 1U 40W power amp will be a tight squeeze, and probably not that sensible from a thermal management point of view.

    Also unless you use two output transformers then you won't get a 40W EI laminated output transformer in 1U. There are now some toroidal output transformers available which may fit, but these are generally expensive.


    As I said, the R&R SOLO manages it - 50W, 2-channel in 1U. Pretty awesome little amp that too. I never noticed it getting that hot when I had one, either.

    I'm looking at bass amps at the mo; the Peavey Tour 450/700 amps look pretty good...enough tonal tweakery to get around the fact that it's probably not got that low-end whump I get from using my Jet City as a power amp.
    "Mains is ouchy if you get it up you" - Sporky
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  • jpfampsjpfamps Frets: 1692
    edited April 2014
    jpfamps said:
    A 1U 40W power amp will be a tight squeeze, and probably not that sensible from a thermal management point of view.

    Also unless you use two output transformers then you won't get a 40W EI laminated output transformer in 1U. There are now some toroidal output transformers available which may fit, but these are generally expensive.


    As I said, the R&R SOLO manages it - 50W, 2-channel in 1U. Pretty awesome little amp that too. I never noticed it getting that hot when I had one, either.

    I'm looking at bass amps at the mo; the Peavey Tour 450/700 amps look pretty good...enough tonal tweakery to get around the fact that it's probably not got that low-end whump I get from using my Jet City as a power amp.
    Not seen the R&R amps.

    The 50W amps does indeed employ torodial mains and output transformers (and indeed choke by the looks of it).

    The valves are mounted horizontally outside the main chassis, with fan cooling, which is a very sensible arrangement as hot air is not blown through the chassis, although I am generally not a huge fan of side venting in rack gear, this can be accomadated.

    Looks an elegant design.
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  • drwiddlydrwiddly Frets: 704
    If you can find one used and are OK with SS, then the Rocktron Velocity 300 is a very good power amp. Can be bridged for 300w into 8ohms and the definition and reactance controls add a bit of fine tuning. Not far off a Matrix IMHO and I have both.
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  • digitalscreamdigitalscream Frets: 14230
    Danny1969 said:

    I used to use the 20/20 ... it's a sweet little amp but has some problems. Air intake is from the side and in a regular rack it can overheat. At least mine did till I modded the rack. It's also not the loudest of amps either, it was enough for me but you could run into problems in certain situations
    I ended up getting one anyway - £300 delivered on eBay. Perhaps not the best deal, but I was being impatient ;) 

    I've only tried it at home, so I can't really tell what the volume's like - I managed to get it up to just under half way with the 11R's volume on 6.5, and it was at the extreme end of home volume. I suspect it's going to depend on what the input headroom's like, but I think it's going to be OK if I run it almost flat-out. I've gigged OK with a Jet City 20W before (albeit with a bit of a lack of headroom), and I can't imagine that was capable of putting out much more than 30W at meltdown settings.

    Interestingly, my 20/20 doesn't have any side-intakes - it's got an intake at the front next to one of the transformers, and exhaust at the back. Did they have more than one version?
    "Mains is ouchy if you get it up you" - Sporky
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  • bignormbignorm Frets: 184
    edited May 2014
    I've only just come across this thread, so apologies for resurrecting it.
    A small footprint valve power amp is the holy grail as far as i'm concerned and have been looking for a way of reducing my rack in size for a couple of years now.
    I use a JMP-1 into a Peavey Classic 60 x 60 power amp which is 3u high for a good reason
    It has three transformers in it, 3 ecc83's and four 6l6's standing up right
    There's no over heating problems with this design as the cooling is done from a large fan at the back of the rack which draws air from the vents at the front across the valves and out the back.
    image
    The nice thing about this power amp is you can run it in mono by just using the left input and turning the right input gain right down.
    It senses no load on the right hand side and turns that side off.
    I've seen mono 120 watt versions on this amp but they are pretty scarce
    Back in the heyday of rack systems, bass player used to run these amps as well as guitarists coz they sound pretty pokey.
    The JMP-1 sounds great with this power amp and the peavey definitely makes a huge difference to the sound coz when i'm in lazy mode at rehearsals, i use a little EH Magnum 44 power amp instead of lugging in the peavey.
    Although the magnum is loud enough to gig with, it doesn't have that warmth or depth of sound you get with the valve power amp.
    You can pick these power amps up for a lot less than £300 and they are worth it mate, mines never let me down ever.
    Its a great amp but I wish there was something out there that would do the same job with less weight.


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  • digitalscreamdigitalscream Frets: 14230
    @bignorm - yes, I had one of those years ago. In fact, it's entirely possible you bought yours from me back on MR ;) It was definitely a great-sounding bit of kit...I used it with an ADA MP-1 (although I never realised it could be run in mono). 

    My complaints with it are nothing to do with the sound - height and weight, really. Comparing it to the 20/20, it's 3U vs 1U and 15kg vs 6kg. I'm a broken shell of a human being, so lugging that around would probably kill me ;)
    "Mains is ouchy if you get it up you" - Sporky
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