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Low Wattage (<4W) Valve Amp with Reverb and Tremolo
Old 18th August 2015 | Show parent
  #31
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🎧 5 years
Quote:
Originally Posted by kingofspain View Post
I liked the 1W setting, but I agree about the 1/4W. I thought the amp had bigger issues with the stock speaker.

Looks like inductive loads are the next thing on my list
Speaker is fine, the box is the issue. Play something like Layla or You Really Got Me and you'll be impressed by how close that small, infinite baffle box gets you. Play anything below a low G and expect to hear just cabinet resonances.

Even inductive loads are just an approximation of the complex loading of a speaker. However assuming you're looking down the road of kit/shop bought + DIY. Maybe some fruitful discussion can be had in this direction:

While you do want trem, and I can understand that running a trem into an overdriven amp is an act of futility, do you have a specific trem in mind that it'd need to be an amp effect? The EHX Pulsar can do the Harmonic Tremolo blondeface thing, but maybe you want to do it the Fender way! The old Fender blackface optical tremolo is nice too - but any box under the soon will do that. Nothing special granted by the amp gods, even the LFO is unremarkable.

Also what reverb? Lots of different tanks to choose from! Do they have to be tube driven?

Last edited by Jazz Noise; 18th August 2015 at 02:33 PM.. Reason: gramm0r
Old 18th August 2015 | Show parent
  #32
Deleted dc388e1
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Quote:
Originally Posted by Jazz Noise View Post
Even inductive loads are just an approximation of the complex loading of a speaker. However assuming you're looking down the road of kit/shop bought + DIY. Maybe some fruitful discussion can be had in this direction:

While you do want trem, and I can understand that running a trem into an overdriven amp is an act of futility, do you have a specific trem in mind that it'd need to be an amp effect? The EHX Pulsar can do the Harmonic Tremolo blondeface thing, but maybe you want to do it the Fender way! The old Fender blackface optical tremolo is nice too - but any box under the soon will do that. Nothing special granted by the amp gods, even the LFO is unremarkable.

Also what reverb? Lots of different tanks to choose from! Do they have to be tube driven?
My goal from the outset has been to go valves all the way, partly because I like thay way they sound, but mainly because I've suspected from the outset that to get what I want will end up as a DIY project.
If I start using op-amps I'll need extra power supplies and a whole host of additional circuitry which will be an unecessary headache.
Since I'm already powering valves it should be a relatively simple task to add a couple more to power the tremolo/reverb circuits.

My second goal was to have everything in one box - something that sits quietly in the corner of my office until I want to play, and has everything I need at the flick of a switch.
As it stands, I've a fully stocked pedal board for use with the band (including a Moog trem pedal), but I'd like to be able to leave all that at our rehearsal space and have a concise rig purely for home use.

I'm currently drawing up a schematic that shoehorns the reverb circuit from a Fender Twin into a Fender Vibrochamp circuit.
Not sure which way to go with the output section yet - whether to stick to the stock output and run it through an attenuator of some kind, or to research a lower output altogether.
Old 18th August 2015 | Show parent
  #33
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mcgruff's Avatar
 
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Originally Posted by Deleted dc388e1 View Post
I did give some thought to getting one of these new generation of practice amps with various fx/modelling built in, but at the end of the day I know I'm not going to form as rich a musical a bond with something that's pretending to a be a guitar amp as with the real deal.
I totally agree but you keep all the feel and character of your amps. All you're replacing is the speaker/cab. If you want to play at low volumes you don't really have a choice. You can't get speaker breakup without shaking some ornaments off the shelves, for example.

Convolution cab sims can produce some very good results if you hunt down some good impulse-response files. They also give you an opportunity to shape the sound using different speaker IR's.

You can also buy a convolution cab sim as a pedal if you don't want to plug into a computer.

I love my tube amps and I'd never plug into anything else (OK maybe a Kemper but only with profiles I'd recorded myself - that's another option incidentally) but if you have to keep it down to loud TV level, I don't think you'll be disappointed.
Old 18th August 2015
  #34
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🎧 5 years
Just to chime in on the really, really low power tube amp quest:

I got a Blackheart Killer Ant a few years back, hoping for apartment-level crunch. It uses 1 12ax7 for the preamp/tone stack, and 1 12ax7 for the power amp/cathode follower. With the right (or perhaps from our perspective, wrong) speaker, it will very much rattle pictures on the walls. If your neighbors are near and anti-guitar, it will absolutely get piss off the neighbors loud, even at only .25 watt output. With a less efficient speaker it's a bit better, and that may buy you enough volume reduction for your situation. The fact remains that even with these little amps that use standard preamp tubes as power tubes, it's gonna get loud if you crank it.

All that said, for being as cheap as it was, the amp is quite responsive and fun to play. The circuit is stupid simple, and the PCBA is well laid out, so modding would not be a chore. I've seen folks adding digital reverb to them, but if you want spring verb, I don't think there's enough room inside to fit a proper one. Tremolo and reverb might be a bit much to shoehorn into the existing design without more major mods. I think you'd really need at least another tube to do that properly. Still, if a used one shows up nearby for not much $$$, it could be a quick way to get a feel for what is possible with this sort of amp.
Old 18th August 2015
  #35
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Ron Vogel's Avatar
 
🎧 10 years
It's personal preference/taste when it comes to PP or single ended. I love both, but PP fits my sound better.

I had a vintage champ for several years...loved it, but was never quite the sound of the Princeton...but then I wanted an LTPI...

Never ends!

Now I have an amp with a twin front end with a DR PI, and a Deluxe/excelsior PP cathode bias output section.

Snobbery never sleeps.
Old 18th August 2015 | Show parent
  #36
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Quote:
Originally Posted by kingofspain View Post
I'm currently drawing up a schematic that shoehorns the reverb circuit from a Fender Twin into a Fender Vibrochamp circuit.
Not sure which way to go with the output section yet - whether to stick to the stock output and run it through an attenuator of some kind, or to research a lower output altogether.
I might look into a parallel single end output configuration for a little more headroom. This type of spring reverb does better with a little more headroom imo.

In one of Kevin O'Connor's TUT series books there's a project single end champ that has a parallel output and you can use a potentiometer to shut one of the output tubes down effectively giving you a 4W output.
Angelia's also has a parallel single end output project.
You can look at old Supro/Oahu's schematics from the late 40's. There's a version also. I believe it's the comet? I have one. It's maybe the best recording amp I've owned to date.

If building your own I would seriously look into power scaling instead of an output attenuator. It basically lowers the plate voltages of all the tubes (or just the power amp tubes your choice) without damage to the power transformer. Sort of like a Variac without damage to the amp.
Old 18th August 2015 | Show parent
  #37
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Ron Vogel's Avatar
 
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Parallel amps won't sound like PP amps...more like a single ended. I had modified an old Magnavox parallel. Had a cool thing going on, but the distortion wasn't very refined...just raw and gnarly. Was a great amp for slide.
Old 18th August 2015 | Show parent
  #38
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Quote:
Originally Posted by Ron Vogel View Post
Parallel amps won't sound like PP amps...more like a single ended.
That's what he's looking to build
Old 18th August 2015 | Show parent
  #39
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🎧 10 years
why not a zvex nano style head? wattage is not your issue after 1 watt. most modern speakers have high sensitivity meaning they can push 90+db 3 meters at 1 watt. Anything over 1 watt will be too loud so why not go lower 1/2 watt 1/4 watt you get the fullness of the amp at high gain without the higher spl.
Old 18th August 2015 | Show parent
  #40
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John Eppstein's Avatar
 
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Quote:
Originally Posted by kingofspain View Post
Interesting. I may be wide of the mark, but I thought asymmetrical clipping was generally considered a good thing in guitar amps, or is that more desirable in pre-amp valves?

I suppose the single ended vs. push/pull isn't really the most important factor as far as the amp I'm looking for here is concerned, although it's always nice to know a little more about how different topologies can effect the end result.

I dunno about asymmetrical clipping being desirable or undesirable, really - it's just a different sound. The push-pull output gives a distortion character more similar to a larger amp. I happen to like it. A lot of people these days seem to fetishize the sound of small single ended amps. I never really did, but I don't dislike that sound, either. It does seem to me that the glorification of single ended sound might possibly be unconscious "sour grapes" thinking - "Well, I have to use a little amp because of my living situation but I'm glad because little amps sound BETTER than big amps." and also spillover from the audiophile idea that Class A is always better (but audiophiles don't drive their amps into clipping.)

Preamps nearly always clip asymmetrically because preamps (in conventional tube amps) are always Class A. To me, I generally prefer the sound of power amp distortion to preamp distortion and I suspect that symmetry of clipping enters into this somewhat, as well as other factors like transformer saturation.

As far as tremolo pedals go, I do like having it built into an amp but some of the pedals offer a greater range of flexibility - different modulation waveforms and some offer a true vibrato option more or less similar to what the old Magnatone amps had, which can be cool.
Old 19th August 2015 | Show parent
  #41
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Ron Vogel's Avatar
 
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Quote:
Originally Posted by John Eppstein View Post
I dunno about asymmetrical clipping being desirable or undesirable, really - it's just a different sound. The push-pull output gives a distortion character more similar to a larger amp. I happen to like it. A lot of people these days seem to fetishize the sound of small single ended amps. I never really did, but I don't dislike that sound, either. It does seem to me that the glorification of single ended sound might possibly be unconscious "sour grapes" thinking - "Well, I have to use a little amp because of my living situation but I'm glad because little amps sound BETTER than big amps." and also spillover from the audiophile idea that Class A is always better (but audiophiles don't drive their amps into clipping.)

Preamps nearly always clip asymmetrically because preamps (in conventional tube amps) are always Class A. To me, I generally prefer the sound of power amp distortion to preamp distortion and I suspect that symmetry of clipping enters into this somewhat, as well as other factors like transformer saturation.

As far as tremolo pedals go, I do like having it built into an amp but some of the pedals offer a greater range of flexibility - different modulation waveforms and some offer a true vibrato option more or less similar to what the old Magnatone amps had, which can be cool.
Well, one of the cool things going for single ended is they tend to have better touch sensitivity overall.

I also like having tremolo built in. It's a different sound...especially on bias wiggle trems like in the smaller fenders with the 1/2 tube PI's. The depth on them has a character the opto trems and pedals just can't achieve.
Old 19th August 2015 | Show parent
  #42
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Quote:
Originally Posted by Mr. Mulcahy View Post
That's what he's looking to build
Yeah, I know...just wanted to point it out in case the thinking was a more complex harmonic content from going parallel-single ended. It will be kind of, but not like when you have PP.

If you were going to do a low-watt single ended and wanted "that" sound, it might be possible using a PP in the preamp...which would be pretty cool!
Old 19th August 2015
  #43
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I would take a SE amp over a PP any day of the week if it had the volume to suit my needs. The harmonic content is more delish. If you get a chance check out a parallel SE amp. Obviously louder than a champ you get more of a feel for what they deliver at higher volumes, and what they deliver is pretty sweet.
Old 19th August 2015 | Show parent
  #44
Deleted dc388e1
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Quote:
Originally Posted by Mr. Mulcahy View Post
I would take a SE amp over a PP any day of the week if it had the volume to suit my needs. The harmonic content is more delish. If you get a chance check out a parallel SE amp. Obviously louder than a champ you get more of a feel for what they deliver at higher volumes, and what they deliver is pretty sweet.
I've definitely settled on a single ended design. I've had a bit of an about face from the Vibro Champ circuit, as I'm not confident I've the technical knowhow to integrate the reverb circuit from another amp.
It occured to me one of my favourite amps was an old Selmer Futurama. Very much in AC4 territory, but it has a 'proper' tremolo stage (the Vox just has a speed control, no depth) plus there are no tricky EF86's to worry about

I'm keen to get started, so I'll probably build it wthout the reverb to start with but leave space in the chassis for the circuit (I'm using the chassis from a Marshall 18W clone so there's room to spare).
Once I'm confident I know what makes the reverb circuit tick, and where best to tap the signal I'll add it in.

I'll run an attenuator between the OT and the speaker. I weighed up using power scaling but decided against, having tried it on another amp and been less than impressed. Plus as John pointed out earlier, at lower voltages you're not saturating the transformer which seems to be one aspect of what makes an amp sound 'good', to my ears at least...

The next question then is which attenuator?

I've been looking at some by Weber. I've never heard a bad word about their speakers, are their attenuators as good?
The MicroMASS looks suitable, and is certainly affordable:

MicroMASS 15w Attenuator

Anyone have any experience of it? Could be one for a whole other thread
Attached Thumbnails
Low Wattage (&lt;4W) Valve Amp with Reverb and Tremolo-futcorv1a.jpg  
Old 19th August 2015
  #45
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Howling Terror's Avatar
 
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I occasionally use the MicroMASS with an Epi valve Jnr. I personally find it difficult to get the tone I want at the correct volume. Get there in the end but it's a balancing act between the low-mids and highs.


Prefer using a couple of Marshall 1 watts into 4X12. Simple to get what I need and they have FX loops too.
Old 20th August 2015 | Show parent
  #46
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John Eppstein's Avatar
 
58 Reviews written
🎧 10 years
Quote:
Originally Posted by Mr. Mulcahy View Post
I would take a SE amp over a PP any day of the week if it had the volume to suit my needs. The harmonic content is more delish.
<snicker>

I have amps of both flavors. I actually have more small single ended amps than push-pull amps because they're much more common. However I really like push-pull amps when I'm trying to get a recorded sound like a big amp.

They're different sounds. One isn't "better" than the other.

"Delish" is the brand name for generic foods at Walgreens.

Quote:
If you get a chance check out a parallel SE amp. Obviously louder than a champ you get more of a feel for what they deliver at higher volumes, and what they deliver is pretty sweet.
He doesn't want a LOUDER amp - he wants a quieter amp that records like a bigger amp.

You're being like the guy who, when asked for recommendations for a steakhouse recommends a veggie bar.
Old 20th August 2015 | Show parent
  #47
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Ron Vogel's Avatar
 
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If you are looking for a small watt amp for high gain use the transformer selection is going to be important.

If the PT is undersized, you will get to much sag, and if the OT is undersized you will get core saturation at full tilt...so the distortion will be real loose and chords will be undefined.

Generally with small high gain amps, getting a good tone for metal is better done by keeping the volume down and using a pedal unless the amp is designed for that purpose.
Old 20th August 2015 | Show parent
  #48
Deleted dc388e1
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Quote:
Originally Posted by Ron Vogel View Post
Generally with small high gain amps, getting a good tone for metal is better done by keeping the volume down and using a pedal unless the amp is designed for that purpose.
I'm not sure when getting a good 'metal' tone became a priority...

Not my thing at all

I'm looking for a ragged, lo-fi tone to suit my ragged, lo-fi technique
Old 20th August 2015
  #49
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🎧 5 years
Quote:
Originally Posted by John Eppstein View Post
He doesn't want a LOUDER amp - he wants a quieter amp that records like a bigger amp.

You're being like the guy who, when asked for recommendations for a steakhouse recommends a veggie bar.

Umm, that was not posted for the OP. read the thread chain (in response to Ron's post)
Old 21st August 2015 | Show parent
  #50
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Ron Vogel's Avatar
 
🎧 10 years
Quote:
Originally Posted by kingofspain View Post
I'm not sure when getting a good 'metal' tone became a priority...

Not my thing at all

I'm looking for a ragged, lo-fi tone to suit my ragged, lo-fi technique
Ahh, for some reason I thought that might have been what you were after from some of the posts. Nevermind then...well, same applies going in the other direction too. Undersized trannies are warm and spongy...even clean.
Old 22nd August 2015
  #51
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Phone Barry at AmpMaker. He is a lovely chap and either he or Pete Towers might get interested enough to help you out.

Not sure if I should say to tell him I sent you or not....


Old 22nd August 2015 | Show parent
  #52
Deleted dc388e1
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Quote:
Originally Posted by ivansc View Post
Phone Barry at AmpMaker. He is a lovely chap and either he or Pete Towers might get interested enough to help you out.

Not sure if I should say to tell him I sent you or not....


I've dealt with Barry before - he's always been very helpful.
I'll be getting the majority of my parts from him but I doubt I could afford the cost of a one-off amp, assuming he'd be interested in building me one
Old 22nd August 2015 | Show parent
  #53
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I was thinking more in terms of either one of them discussing the "how" of adding a valve reverb tank to a CB amp.

I actually hate the use of smartass abbreviations, but to make a point I used CB to mean Cathode Biased. As far as I am concerned, the old cathode biased amps are IT for big fat creamy sounds - clean or slightly dirty.
I haven`t a clue about uber-overdriven sounds as I never use them, suspect you are the same.
Old 23rd August 2015 | Show parent
  #54
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John Eppstein's Avatar
 
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Quote:
Originally Posted by ivansc View Post
I was thinking more in terms of either one of them discussing the "how" of adding a valve reverb tank to a CB amp.

I actually hate the use of smartass abbreviations, but to make a point I used CB to mean Cathode Biased. As far as I am concerned, the old cathode biased amps are IT for big fat creamy sounds - clean or slightly dirty.
I haven`t a clue about uber-overdriven sounds as I never use them, suspect you are the same.
I totally fail to understand the fetishism for cathode biased (beginner's) amps these days. For me the holy grail of guitar amp tone is, depending on application, the '59/'59 4x10 Bassman, the '61-'63 brownfaced Basssman,, and the '64-'65 Super Reverb (Deluxe Reverb ain't bad, either), none of which were cathode biased.

Cathode bias is for low headroom student amps.

It's the cheap way to do it.

And adding a reverb tank is the same regardless of the biasing. You need a driver circuit and a mixer stage.

Last edited by John Eppstein; 23rd August 2015 at 11:33 AM..
Old 23rd August 2015 | Show parent
  #55
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Quote:
Originally Posted by John Eppstein View Post
I totally fail to understand the fetishism for cathode biased (beginner's) amps these days. For me the holy grail of guitar amp tone is, depending on application, the '59/'59 4x10 Bassman, the '61-'63 brownfaced Basssman,, and the '64-'65 Super Reverb (Deluxe Reverb ain't bad, either), none of which were cathode biased.

Cathode bias is for low headroom student amps.

It's the cheap way to do it.

And adding a reverb tank is the same regardless of the biasing. You need a driver circuit and a mixer stage.
You aren`t old enough, John.(grin) I grew up on cathode biased amps and love everything about them. Only more recent amp that I ever really liked was my `63 wheat and oxblood Tremolux. Are you are saying you prefer a deluxe reverb to a tweed wide panel deluxe?
If so, I guess it is down to the style of music we like to play rather than which amp is better. Ask Neil Young and a few other famous users why THEY like CB amps.
Old 24th August 2015 | Show parent
  #56
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Quote:
Originally Posted by ivansc View Post
You aren`t old enough, John.(grin) I grew up on cathode biased amps and love everything about them. Only more recent amp that I ever really liked was my `63 wheat and oxblood Tremolux. Are you are saying you prefer a deluxe reverb to a tweed wide panel deluxe?
If so, I guess it is down to the style of music we like to play rather than which amp is better. Ask Neil Young and a few other famous users why THEY like CB amps.
I'm saying I prefer a '58/'59 tweed Bassman or Bandmaster to a tweed Deluxe.

Which output tubes did your Tremolux use? Was it one of the very rare ones with the 6BQ5/EL84s?
Old 24th August 2015 | Show parent
  #57
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Like a fool, I sold it when I moved to Nashville in 81, thinking I would just pick up another when |I got there.
Little did I know at the time!
I honestly don`t recall what valves it had in it, but I do remember someone had replaced the speakers with Marshall-badged Celestion tens.
Old 24th August 2015
  #58
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Was Neil Young not a Bassman user??
Old 24th August 2015 | Show parent
  #59
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Best known for tweed deluxes. Wiki his name deluxe and whizzer.
Old 28th August 2015
  #60
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1 watt amp, preamp tube on the right, power on the left. Can be used as a OD pedal. It has a built in speaker load active when the speaker is unplugged.
I play it through a 2X12 cab, I love it. No effects unless you use pedals.
Attached Thumbnails
Low Wattage (&lt;4W) Valve Amp with Reverb and Tremolo-sdc10410.jpg  
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