Changing to amp without effects loop

[ef37a]

First of all, I am STILL being kept in the dark about all these new posts!

"I wonder if there is a foot pedal that can blend the two channels so I could try to mix the effects and clean channel together and or play one at a time. That would be cool."

Cool and expensive as a special I bet! Can I try to pin down exactly what you want?

I think you mean two (or more? ) high Z guitar inputs feeding pots to set levels and each channel controlled by switches. Thus you could have "A" or "B" or a mix of both?

That is just a dual jfet op amp and another bipolar op amp, two pots, two switches and a tin. Not rocket science but I have no idea if it exists. I shall ask in another place!

Dave.

[ef37a]

https://www.gak.co.uk/en/boss-ls-2/1286 ... 7QodZMgGYA

That ^ look a possibility. 80 quid is a fair wedge, especially since the pedal has functions you probably don't need but I doubt you could get the simple version I described made for £100?

It is also 9volts powered and I think you would run into headroom problems.

Dave.

[Music Wolf]

https://www.gak.co.uk/en/boss-ls-2/1286 ... 7QodZMgGYA

.

The LS-2 is truly the Swiss Army Knife of pedals. I've had mine for years and it's been in and out of pedal boards but I'll never get rid because I keep finding uses for it.

In fact seeing this post has made me think that my latest pedal board could benefit from it and, seeing as I'll be putting everything into a new case after Christmas.....................

I trip to the loft coming up

[ef37a]

https://www.gak.co.uk/en/boss-ls-2/1286 ... 7QodZMgGYA

.

The LS-2 is truly the Swiss Army Knife of pedals. I've had mine for years and it's been in and out of pedal boards but I'll never get rid because I keep finding uses for it.

In fact seeing this post has made me think that my latest pedal board could benefit from it and, seeing as I'll be putting everything into a new case after Christmas.....................

I trip to the loft coming up

Glad to be of service. Watch those steps! Keep off the crimble sherry.

Dave.

[DC-Choppah]

https://www.gak.co.uk/en/boss-ls-2/1286 ... 7QodZMgGYA

That ^ look a possibility. 80 quid is a fair wedge, especially since the pedal has functions you probably don't need but I doubt you could get the simple version I described made for £100?

It is also 9volts powered and I think you would run into headroom problems.

Dave.

Thank you kindly! Always a pleasure. I am liking this amp switcher to give me one Fender clean channel and one effects channel.

Headroom problems? Care to elaborate? I am finding other stuff out there.
http://lehle.com/EN/Lehle-Dual-SGoS

[ef37a]

Headroom problems:

A 9 volt powered pedal will, at the very best have an rms output of 3 volts, about +9dBu.
That gives enough headroom for other, 9V guitar based devices but maybe not for mains powered gear that was normally run through an FX loop but then I don't know the levels involved with the Roland?

Dave.

[CS70]

I have played for decades with a Roland JC-120 amp which has an effects loop that I use to drive my rack of effects, tuner.

I have fallen in love with this amp: http://www.sweetwater.com/store/detail/65DeluxeRVWR

Only problem is I just realized it does not have an effects loop.

I don't have the new amp yet, but am trying to be prepared for when it comes.

So what is the deal with switching over to an amp without an effects loop. It's just been a long time since I thought about such things.

Is there a known simple mod to give the amp an effects loop?

The only real issue that exists concerns the the distortion resulting from preamp overdrive. Effects like delay, phasing etc will apply before the signal hits the preamp and will sound different - distorting a signal mixed with delay it's not the same as distorting first and applying delay to the result. Different settings will help, but it's just a different sound.

The solution is not to use preamp distortion, but get it from pedals before hitting the delay or modulation. For songs with delay, I use clean amp setting and get the juice from an overdrive and a DS1. Of course if what you have fallen in love with is the amp distortion sound, you're a bit out of luck.

[resistorman]

If it sounds as good as the original, you may find that just plugging in and playing will do it for you!

[DC-Choppah]

The solution is not to use preamp distortion, but get it from pedals before hitting the delay or modulation. For songs with delay, I use clean amp setting and get the juice from an overdrive and a DS1. Of course if what you have fallen in love with is the amp distortion sound, you're a bit out of luck.

Thanks for that. That is what I will do. It is the clean,singing, jazzy sound of the amp I like. I won't use its on-board distortion - just leave it clean. I like my pedals for overdrive and distortion. It is just that theses Fender amps seem to sound good when you just plug right in directly.

So, I am going to try just running the effects rack right into the amp and see what it sounds like. Amp won't be here for a week or so. I'll check back in when it comes after I see what it sounds like without the effects loop.

If the effects change the amp's clean sound, I'll look into the amp switcher so I can run into channel 2 clean and use channel 1 as the effects channel.

I am wondering about one thing regarding these amp switchers though.

The Boss pedal is active and uses a buffer circuit so it must have some effect on the tone quality.

Meanwhile, it looks like it is possible to set up an amp switcher with volume controls and do it all passively. I like Morley pedals, and am thinking about this:

http://www.morleypedals.com/daby.html

and then 2 of these (to control the level of each channel):

http://www.morleypedals.com/dm2vo.html

These appear to be 100% passive, and don't need batteries.

I am wondering which way will preserve the clean sound of the Fender amp, or if it even matters?

[Drew Stephenson]

Or you could try something like a Belcat ABS 520, which does your switching and has static level controls? It's only AB not ABY though.

[ef37a]

"The Boss pedal is active and uses a buffer circuit so it must have some effect on the tone quality."

One of the principles of an electronic "buffer" is that it does NOT change the nature of the signal! In this context a buffer converts a medium to high source impedance, which is prey to interference and HF loss, to a low source impedance which is not.

The whole clamour and hype about so called "true" bypass is based upon a wrong understanding of how signals are transferred and interact with cables and other factors. Often the proponents of "TB" cite the fact that a lot of prestigious studio effects are TB? They conveniently omit to tell you that prestigious STUDIOS always have low impedance sources to feed such equipment!

Yes, there are a few very old "classic" effects pedals that do not work as they should driven from a low Z buffer but that is a design "fault" in the original pedal design NOT a fault of doing things properly! Had active guitars been around at the time they would have showed the same problem.

Dave.

[Hugh Robjohns]

The Boss pedal is active and uses a buffer circuit so it must have some effect on the tone quality.

Only if it's badly designed!

I'm 100% with Dave on this one. The whole point of a buffer circuit is to isolate the source from the destination, specifically so that the things that would otherwise cause some effect on the tone quality no longer can!

Electric guitars work in a high impedance environment, and the inherent consequence of that is a pronounced susceptibility to tonal changes caused by the length and type of guitar lead, the input design of the amplifier, and any effects pedals connected in between.

No one with any electronic engineering competence would ever have designed such a system... but it is what it is, and some of that variability is a part of the instrument character.

However, if you connect the guitar into an active buffer, the guitar sees the very high input impedance it needs to work properly, and everything after the buffer is driven from a very low impedance which optimises the voltage-transfer paradigm that the electronics require, removes any nonsense effects of different cable types, and helps to reduce noise.

Provided the active buffer has sufficient headroom, gain band-width and noise performance -- all pretty trivial things to design for in this situation -- the buffer should be completely transparent and inaudible and provide a totally reliable and consistent experience regardless of what signal processing yo introduce downstream.

H

[ef37a]

Thank you Hugh...Phew!
I am always worried when I see H J has responded after my waffle!

Little known facts about the highly subjective, boooteek, highly polarized guitar "interface" world?

Many Audio Interfaces had "high Z" inputs that were well below the "magic meg" some as low as 100k Ohms. In my ten years of computer audio interests and 1,000s of posts and reading of reviews I don't recall anyone noticing? In fact MOST reviewers take the instrument input impedance as read and never bother to mention it!

Guitar amps with high/low input jacks were very common for many years. Few players ever realized that plugging into the low sensitivity input dropped the Z massively to about 68k!

Much guff is spoken about "discrete FET buffers". In fact a single JFET is pretty non-linear and even the humble TL072 makes a vastly more transparent one.

Dave.

[Hugh Robjohns]

I am always worried when I see H J has responded after my waffle!

I like to keep you on your toes, Dave... as you do, me!

Many Audio Interfaces had "high Z" inputs that were well below the "magic meg" some as low as 100k Ohms.

I'm not entirely sure where this 'magic meg' idea came from. Most valve guitar amps I've come across seem to be closer to 250K-500k -- which is absolutely fine.

I think the 'magic meg' came from active DI boxes which, because they would normally be expected to 'bridge' the guitar-amp connection, need an extremely high input impedance to avoid reducing the amp's effective input impedance. For example, a 1M active DI across a 250K amp input only reduces the effective input impedance to 200K, which isn't low enough to have any audible effect on the guitar.

Much guff is spoken about "discrete FET buffers". In fact a single JFET is pretty non-linear ....

True... but hopefully non-linear in a way which adds some pleasant musical colouration which is beneficial in the absence of a guitar amp's colouration!

H

[ef37a]

Valve amps almost always had and have a 1 meg Ohm grid resistor and a stopper R of about 68k. This, with the valve's input capacitance formed an RF filter. Some amps reduced the stopper or eliminated it altogether and paid the RFI price!

I understand that since guitar amps were originally just the back end of a radio set, those had a high grid leak on the first audio valve so as not to load the detector circuit. For guitar use 1M was, as you say, not needed but the myth was born! They are legion!...

Many Phase Inverters (yes, I know it should be "polarity" but what can yer do?) still have anode loads that differ by 20% in the mythical belief that this "balances" the drive. In fact the balance correction is closer to 5% and so that makes things worse! Since guitar amps actually benefit subjectively from an OOB drive nobody minds.

Dave.

[DC-Choppah]

The Boss pedal is active and uses a buffer circuit so it must have some effect on the tone quality.

Only if it's badly designed!

I'm 100% with Dave on this one. The whole point of a buffer circuit is to isolate the source from the destination, specifically so that the things that would otherwise cause some effect on the tone quality no longer can!

Electric guitars work in a high impedance environment, and the inherent consequence of that is a pronounced susceptibility to tonal changes caused by the length and type of guitar lead, the input design of the amplifier, and any effects pedals connected in between.

No one with any electronic engineering competence would ever have designed such a system... but it is what it is, and some of that variability is a part of the instrument character.

However, if you connect the guitar into an active buffer, the guitar sees the very high input impedance it needs to work properly, and everything after the buffer is driven from a very low impedance which optimises the voltage-transfer paradigm that the electronics require, removes any nonsense effects of different cable types, and helps to reduce noise.

Provided the active buffer has sufficient headroom, gain band-width and noise performance -- all pretty trivial things to design for in this situation -- the buffer should be completely transparent and inaudible and provide a totally reliable and consistent experience regardless of what signal processing yo introduce downstream.

H

OK. Makes sense.

But I have been auditioning lots of amps lately and trying to just follow my ears. That took my to the Fender Deluxe Reverb. Something about the way that it interacts with the guitar. It is not neutral (like my JC-120) was, but instead adds to the sound and feel - affects the way I play. So I want to preserve that but then also have the option to run the full effects chain - if that is possible.

It seems to me that the buffer could affect the sound though as you describe. (I'll have to try this when the amp comes in).

Scenario A: I run the guitar direct to the amp and like the sound. The guitar has a nominal output impedance of 10K Ohms while the amp has a nominal input impedance of 136K Ohms.

Scenario B: I run the guitar into a buffer which has a 1M Ohm input impedance and 100 Ohm output impedance.

So in scenario B amp is being driven by a low impedance (100 Ohm) input while in Scenario A it was being driven by a higher impedance (10 k Ohm) input.

If the amp has been somehow designed to operate with the 'guitar plugged directly in' and expects this 10 k Ohm input impedance, perhaps it might sound different being driven by the buffer then.

[Hugh Robjohns]

I understand what you are saying, and how the guitar/amp interface affects the way you play.

It is possible that using a buffer between the guitar and amp am affect that interaction, but equally it might not -- it really depends what the interaction is about. For example, if the positive interactive traits are due to the input impedance loading effects on the pickups, or the HF damping an active buffer would potentially change things Ian deleterious way. On the other hand, if it is more to do with signal levels and dynamics the buffer might not interfere at all.

Certainly, the relationship between the guitar pickups and amp input can be a complex one, and you'll need to experiment to see what works for you and what configuration best delivers what you want/need.

From an engineering point of view, the best technical approach is to buffer the pickups with their high source impedance since that provides the best flexibility and consistency. In effect, that's what your previous amp provided, with the amp's front end buffering the guitar from the effects loop.

To achieve a similar configuration with the new amp you would need an active buffer between the guitar and the effect pedal chain -- but the critical aspect is that the buffer mus be one that provides the right kind of loading for the guitar to give you the playing 'feel' you enjoy. Perhaps a valve-based pedal might be more to your liking than a solid-state one, for example.

H

[ef37a]

The whole world of guitar/amp "tone" is one fraught with myth and legend and people make extreme claims for things that are at best only detectable in a carefully designed A/B test or are in fact inaudible!

I must have read over the years close to a hundred "night and day" claims for NOS valves or special selected ones of very high price. Not ONCE do I recall a before and after recording? The very idea of a voltage table of DC conditions* or a gain/frequency check is laughable.

So, it all boils down to ONE man, in HIS room, HIS amp and HIS guitar/cable etc. There is almost no valid data you can take from such claims that will help you.

What is very hard to see (and I have had this argument before elsewhere!) is how a guitar amplifier with a conventional valve input stage, i.e. one with 1 meg and a stopper resistor can possibly "know" what the source impedance of the guitar or pedal is? At best, if the guitar's volume pot is backed off there will be some cable loss of high frequencies but this effect should be obvious and known to any moderately experienced player?

None of the above means guys can't jam and experiment and have fun. Just don't make unsupported claims!

*Especially when different valve "numbers" are fitted, e.g. a 12AT7 for a 12AX7. The biasing will be wrong and that will affect the sound but if we don't get told how the bias is shifted how can we make valid judgements? BTW, unless you really understand the circuits, don't do this!

Dave.

[CS70]

The whole world of guitar/amp "tone" is one fraught with myth and legend and people make extreme claims for things that are at best only detectable in a carefully designed A/B test or are in fact inaudible!

Granted.

Just as note, however, for the seasoned electric guitarist it's seldom the sound that it's the issue (you can always build it with effects, and it mostly depends on your fingers anyways) but the way that the amp reacts - which is notable (to me at least) with overdriven or distorted sounds.

Amp/pedals combination which I like have a certain "bounce" to them, that is when you hit a note you can use your hands and body position to make it sing only for so long, or sustain more, to emphasize attack, body, or sustain or keep it clear or slurry and so on and on.. and you have the feel that whatever you want to do the amp responds quickly, precisely and all these details show out clearly (at least to my ears) in what comes out of the speaker (which by itself has something to say.. it's a different feel to play a 4x12 than a 10x1 combo).

So it's all about the feel of playing rather than the sound characteristics by themselves.

Just to be said, I have very little idea of what part of the electronics are the ones contributing or not

[ef37a]

I totally agree CS70.
Your experience departs from mine at the electronics level. Mine from yours at the artistic/experience/"feel" level. I do however know of at least supremely gifted guitarist who is also a brilliant designer of amplifiers and follows "Da Rules"! (his products have been favourably reviewed in SoS) .

Virtually everything you, and other musicians say can be applied to completely acoustic instruments. Do fiddle players argue "night and day" about different rosins?

What is often forgotten in all this is the fact that to stay in business an amp mnfctr has to not only MAKE a good product once but 10,000 times and try to make them all the same.

That's Engineering!

Dave.

[DC-Choppah]

OK. Been playing a lot with the new amp and tried many configurations for getting a clean sound I like. There are some very clear lessons I have learned to get the sound I am after in my head.

1) The amp has 2-channels (clean vs. reverb) and for each channel there are 2 inputs (1 and 2) Input 1 is 350k impedance while input 2 is 1 Meg Ohm. The reverb channel is the good one for the Fender clean tone. Plugging directly into input 1 robs the sound of the low end. So I only want to use input 2 of the reverb channel for my clean tone. Input 1 is thinning out the sound and is artificial sounding and 'electronic' sounding.

2) Using a high impedance buffer between the guitar and the amp is either sounding better than plugging straight in, or has no change (depending on how the buffer is set up). I am using the Barber Gain Changer as my buffer. I can set it to be very clean, with nice tone and with the output turned down. This lets me set the amp at higher levels which bring out the tone of the tube amp more and makes it sing and sustain more. This is my favorite setting. I could never get this kind of Fender clean sound from my JC-120.

3) If I make the gain changer neutral it has no effect on the sound. Sounds the same as plugging in directly.

Now I have to figure out how to keep this new clean sound using the reverb channel of the amp, but be able to switch to the clean channel with all the rest of the effects rack in front. The clean channel reminds me of the JC-120 sound. Very true and clear. Not jazzy, just clean and pure.

Need to decide which of the ABY switches to use I guess. I want to keep the option to mix the 'effects' and 'dry' channels (that's my notion of fusion: Rock + Jazz).

[Sam Spoons]

This might do what you need https://www.thomann.de/gb/one_control_white_loop.htm

[ore_terra]

There's no such thing as a clean channel in a deluxe reverb, mate. They just sound different, and effects only apply to one of them (there are mods to change this). I.e., I prefer teles and strats in normal channel, and everything else in the other.

Only volume knob and your right hand will determine how dirty the tone will get!

Regarding inputs 1 and 2 in each channel, you're the 1st one I'm aware that prefers 2 rather than 1

1 is louder, but also has a richer tone IMO.

Is there any reason why you wanna use both channels? I wouldnt use an ABY box and put everything in the vibrato channel, on top of your clean base tone.

If you're worried about having too long pedals chain sucking tone you may want to go, apart of that buffer, to a looper pedal. That way you'll be able to "remove" stuff from the chain when not enabled.

Keep trying with de Deluxe Reverb! They're great including the reissues like yours. Of you come from the Roland you'll be looking for that 100% clean concept that just does not exist in a Deluxe Reverb haha (well, it does at low volumes).

Dont be afraid to raise it a little bit and get some of the harmonics and warmth of the slightly overdriven deluxe reverb.

The Petra Flowers

[DC-Choppah]

Oops, yes I had it backwards, input 1 is the one that sounds good and input 2 lacks depth.

The amp has 2 channels. The one on the left has no reverb or vibrato and has a pure, less Fender-like sound. The one on the right is the 'reverb/vibrato' channel, but also sounds different and has more of the Fender-like sound and drive. But for both, the input 1 always sounds better with more depth.

OK, I am going to try your advice ore_terra and try the effects loop into the right channel too. I am just starting to play with how to integrate the rack into this.

I am normally too eager to just get set up and go and focus on the music, but lately I have been trying to go back and rethink everything to get good tone (and avoid getting annoying tone if you know what I mean).

[DC-Choppah]

This might do what you need https://www.thomann.de/gb/one_control_white_loop.htm

OK cool, that's new to me.

I wish I could have all this stuff to try in different ways and see how it all sounds first.