Valve amp features

[Kevin Dean]

Why don't Valve amps have features like  compression etc built in , like a lot of solid state amps have ?

[Woodinblack]

Turn the volume flat out - you will find it compresses quite a lot!

But in seriousness, a valve amp circuit is very simple compared to other amps, an actual compressor requires an active amplifier with a feedback circuit, which can be done with valves but would need quite a few of them* so would make them pretty expensive. Especially when you can just get a cheap compressor and put in in front.

Or turn the volume up

 

Correction - you could do a basic compressor with another 3 valves..

Edited May 9, 2018 by Woodinblack

[Ashdown Engineering]

11 hours ago, Kevin Dean said:

Why don't Valve amps have features like  compression etc built in , like a lot of solid state amps have ?

I'll just leave this here...

https://ashdownmusic.com/collections/legacy/products/bta-400

;-)

[Bigwan]

10 hours ago, Ashdown Engineering said:

I'll just leave this here...

https://ashdownmusic.com/collections/legacy/products/bta-400

;-)

Solid state preamp? Awesome, but I don't think it's what the OP is getting at... 

Would have killed for one of those once upon a time... 

[Woodinblack]

11 hours ago, Ashdown Engineering said:

I'll just leave this here...

https://ashdownmusic.com/collections/legacy/products/bta-400

;-)

Product discontinued - I guess no-one makes one

 

[TheGreek]

Close enough?

https://www.ebay.co.uk/itm/Ashdown-Bta-300-valve-bass-head-with-flight-case/253610622120?hash=item3b0c5efca8:g:ZTEAAOSw5MBa8cCn

[skidder652003]

On 5/10/2018 at 22:01, TheGreek said:

Close enough?

https://www.ebay.co.uk/itm/Ashdown-Bta-300-valve-bass-head-with-flight-case/253610622120?hash=item3b0c5efca8:g:ZTEAAOSw5MBa8cCn

£1400??!! Don't think so

[Phil Starr]

I'm doing this remembering repairing kit back in the very early 70's, well 1970 actually. My memory may be a bit iffy at that distance.

Compression is something valve amps do naturally partly down to the valves themselves but also due to the saturation of the output transformer. Basically they just peter out as the output rises giving a nice soft sounding distortion as they over loaded. Guitarists used this to create all the sounds of early rock music. Combined with the feedback you get at ridiculously high levels it also gave them a lot of sustain to play with. Everyone forgets that most of these amps were pretty unreliable and a band running four valve amps on stage plus often valve PA amps was experiencing a lot of technical failures. Plus back problems from carrying the amps. Having 20 KT88's on stage was a nightmare to be honest.

Transistor amps were coming in by then WEM (not much more reliable) and later HH for PA followed by early guitar and bass versions. They were certainly cheaper and quickly became more reliable but transistor amps really distort unpleasantly when overloaded so we looked for a way of getting that gentle overload that the old amps gave. Compression was what was needed so compression on instrument amps started as an effect to give 'valve sound'

The first compressors I encountered used ordinary car bulbs to compress the sound. At high power they get hot and their resistance goes up, put the signal through a bulb pick it up with a photocell and bingo, compression. The next stage was a voltage controlled amplifier. Take the output and use it to control the volume or gain of the amp and you get compression. These were often adapted from tape recorder automatic volume circuits and used FET's as the controlling element. By about 1974 integrated circuits took over thousands of components in a single package. You could get undistorted compression at will but you wouldn't do that complexity with valves.

So you wouldn't simulate valve sound with valves for obvious reasons. They still make optical compressors as an effect but with VCA's you can get completely controllable compression which is largely done digitally nowadays anyway. Valve based computer anyone?

If anyone is interested https://www.soundonsound.com/sound-advice/q-what-optical-compression

[3below]

On 18/05/2018 at 08:01, Phil Starr said:

........ Everyone forgets that most of these amps were pretty unreliable and a band running four valve amps on stage plus often valve PA amps was experiencing a lot of technical failures. 

 

Well pointed out, I had also forgotten this, memories of frequent repairs to my AC50 return.  Seem to remember output transformers in many guitarists 100W valve amps failing as well.

[xgsjx]

I don't think tacked on compressors or octavers are a good thing.  An amp really should just have input & output gain & some tone controls.  Leave the effects to dedicated units.

[Woodinblack]

2 minutes ago, xgsjx said:

An amp really should just have input & output gain & some tone controls.  

Why's that?

I love having the overdrive (and I suppose the spectracomp) in the RH450 that I gig with. If I didn't have them I would have to have something else.

If  was gigging as a guitarist at the moment I would just have a boss katana and nothing else.

[xgsjx]

6 minutes ago, Woodinblack said:

Why's that?

I love having the overdrive (and I suppose the spectracomp) in the RH450 that I gig with. If I didn't have them I would have to have something else.

If  was gigging as a guitarist at the moment I would just have a boss katana and nothing else.

With the ones I've tried, they usually pale in comparison to having a dedicated pedal for the job.
Though I've never tried the RH450, so I've no idea if the overdrive on it is good or not.

You make a point though.  A guitarist friend has a Kempler & it sounds pretty good (though for the money, it damn well should do).

[Woodinblack]

23 minutes ago, xgsjx said:

With the ones I've tried, they usually pale in comparison to having a dedicated pedal for the job.

I have some dedicated pedals for overdrive, but don't often use them. The overdrive in the 450 I look at more for 'valving it up a bit', so not overdrive as such, just adding a bit of vintage.

So i have two bits on the pedal, any rock or older song goes for preset 2 (half overdrive), any modern or quiet song gets 1 (clean).

Quote

You make a point though.  A guitarist friend has a Kempler & it sounds pretty good (though for the money, it damn well should do).

The kempler is great but as you said, expensive. The Boss Katana is from about £170 upwards depending on model. I have several friends (who gig) with them now and they do literally rave about them.

Edited May 20, 2018 by Woodinblack

[Merton]

Didn’t the mighty Trace V8 have a valve compressor circuit?

What about the Laney Nexus valve head, does that have one?

[Happy Jack]

On 5/18/2018 at 08:01, Phil Starr said:

I'm doing this remembering repairing kit back in the very early 70's, well 1970 actually. My memory may be a bit iffy at that distance.

Compression is something valve amps do naturally partly down to the valves themselves but also due to the saturation of the output transformer. Basically they just peter out as the output rises giving a nice soft sounding distortion as they over loaded. Guitarists used this to create all the sounds of early rock music. Combined with the feedback you get at ridiculously high levels it also gave them a lot of sustain to play with. Everyone forgets that most of these amps were pretty unreliable and a band running four valve amps on stage plus often valve PA amps was experiencing a lot of technical failures. Plus back problems from carrying the amps. Having 20 KT88's on stage was a nightmare to be honest.

Transistor amps were coming in by then WEM (not much more reliable) and later HH for PA followed by early guitar and bass versions. They were certainly cheaper and quickly became more reliable but transistor amps really distort unpleasantly when overloaded so we looked for a way of getting that gentle overload that the old amps gave. Compression was what was needed so compression on instrument amps started as an effect to give 'valve sound'

The first compressors I encountered used ordinary car bulbs to compress the sound. At high power they get hot and their resistance goes up, put the signal through a bulb pick it up with a photocell and bingo, compression. The next stage was a voltage controlled amplifier. Take the output and use it to control the volume or gain of the amp and you get compression. These were often adapted from tape recorder automatic volume circuits and used FET's as the controlling element. By about 1974 integrated circuits took over thousands of components in a single package. You could get undistorted compression at will but you wouldn't do that complexity with valves.

So you wouldn't simulate valve sound with valves for obvious reasons. They still make optical compressors as an effect but with VCA's you can get completely controllable compression which is largely done digitally nowadays anyway. Valve based computer anyone?

If anyone is interested https://www.soundonsound.com/sound-advice/q-what-optical-compression

It's reading posts like this that truly underlines how little I understand about what's going on inside the expensive boxes I buy.

 

[thodrik]

My Trace Elliot V6 has ‘deep’ and ‘high’ pre shapes and push/pull mid frequency alteration setting, all of which serve to detract from the sound from the amp. 

[LukeFRC]

11 hours ago, Woodinblack said:

Why's that?

I love having the overdrive (and I suppose the spectracomp) in the RH450 that I gig with. If I didn't have them I would have to have something else.

If  was gigging as a guitarist at the moment I would just have a boss katana and nothing else.

Your amp is I think converting the signal to a digital one and back again, doing all sorts of clever power management and compression and simulating a certain sound - the RH450 is a pretty awesome bit of kit ... 

but very different from an all analogue setup - where the more stuff you put in the signal path the more possible distortion, phase issues and anomalies you will get from them. If you look at the guts of a lot of valve amps they will look quite simple in terms of number of parts. There is a difference I think in terms of the sound. Live, by the time it's gone through a pa the RH450 will work well and it's feature set will help... but I doubt you would ever mic one up in the recording studio...

[Woodinblack]

1 minute ago, LukeFRC said:

but very different from an all analogue setup - where the more stuff you put in the signal path the more possible distortion, phase issues and anomalies you will get from them. If you look at the guts of a lot of valve amps they will look quite simple in terms of number of parts. 

Indeed but we weren't talking about analogue amplifiers specifically, I was referring to the posts that amplifiers shouldn't have effects.

Personally, I don't understand why you would use an amplifier at all if you were recording.

[LukeFRC]

Heft? 

 

 

 

(Runs)

[xgsjx]

12 minutes ago, Woodinblack said:

Personally, I don't understand why you would use an amplifier at all if you were recording.

With a valve amp, sometimes it can be hard to recreate the sound of the valve power amp section.  

Back to fx on amps...  I suppose when you think about it, most valve amps have a built in overdrive.
I still think a dedicated pedal for things like octave, chorus, compressor etc gives better results.  Even a decent multi fx unit should provide better results (though most multi fx are not very good at dirt).