I'm not a better man than any one here, i'm just someone who happens to have been teached some engineering and math stuff a long time ago and have a tendency to overthink sometimes  :lmao: :duh

Regarding your approximate concept of tube tone, we do agree:
Tone shaping (guitar pickup, guitar tone and volume circuit, even picking technique, guitar cable, components that might be added/set before the first buffer; then if you put it in pre-clipping EQ/tone tweaking stage) - half wave clipping - tone shaping circuit - half wave clipping - tone shaping circuit - (repete those two for the number of triod stages you have) - tone stack - symetrical clipping (push pull stage) - tone shaping device (guitar speaker).

In my opinion, chosing between high input impedance or not is a choice (I do not pretend one is "better" than the other) impacting the first tone shaping stage of your rig even if it's not the one you would think you act on if you are working on *an amp* or *a stompbox*. Good on you if with your choice you make a good sounding overall rig, which is the case here. And I've heard a lot of people make good use of very low input impedence devices (old school fuzz boxes for instance), I just can't get my head around it as it implies some dynamically changing tone shaping. That doesn't mean it's not right to do so.
And according to Hartley Peavey, the output transformer of tube amps could very well perform also some dynamically changing tone shaping, which is hard to perfectly emulate, but also very hard to understand in for me.

Prior to answer questions 1 and 2, you may want to have your speaker ohm ratting question answered.
Basically, SS amps are not as selective as Tube amps in this regards. Usually any 8ohm load will do, but you can be pretty safe with 16 also.

I won't be of a lot of help since I am not used to work on amps, but I kinda lurk here to learn helpfull things.

First questions to ask are:
1° are these amps working? If it ain't broken, don't fix it.
2° if they are not working properly, what are the symptomes? Descibe how it reacts to a guitar plugged in.
3° you seem to have the schematics for one of these. Post it here, It will definitively help your case. Maybe start with fixing the amp for which you have the schematics, it will be easier for people here to help you with this one.
4° try to take some quality pics of the board of the other amp, it may help.

I agree that tone focus is key for the following reason:
- high order harmonics do sound bad, and some of them are even not hamonically correct (especially those from 7x fundamental frequency and higher). Filtering them out both before and after clipping is a good idea, especially after heavy clipping (square wave signals contain a lot of them). Before clipping they usually are a lot less prominent due to the natural behaviour of a guitar.
- when playing several notes (chords, double stops, etc), you will generate some intermodulation distortion, which is not bad in powerchords (the only case where the intermodulation actually adds harmonically related frequencies), but will be dissonant for most other intervals. The more clipping, the more intermodulation. You can filter some of it with low end filtering after clipping but the best way to limit that is to reduce the bandwidth before clipping, especially lowest end, cause you want to avoid clipped-generated harmonics of the lowest notes of your chord with the same amplitude as the fondamental of higher notes of your chord (especially considering a major third will be generated as the 5th harmonic... not that good in a minor chord...).
- highs ride on lows. Clipping apply to the overall signal. So your highs will be asymetrically clipped (here comes the south after even harmonics) with a modulation of this clipping. To me it sounds quite good, but applies only when a) your clipping device sees some harmonics that are there already b) you do not squash them by changing the whole thing into a square wave anyway (ie clipping the lows so hard you don't even let any room to still have the original highs in the signal). So this applies more in the region between clean with a bit of warmth and slight crunch.

It seems your device uses just these concepts, and it sounds good, so you must be doing something right. What I'm more interested in these days is the last of the conceptual aspects I detailed above. Accoustically, an electric guitar will have a lot of harmonics, but with a lot less amplitude than the fondamental and first octave. Put some low input impedance stompboxes and a long guitar cable with capacitance problems after a passive pickup and you have very few harmonics to enhance your "warmer clean" tone.

Oh and back on topic, you published a schematic of something that according to the sound sampled you put does work great. So even if I am always tempted to digress and ask for details that are not always relevant to the point (best way I found to learn things), you must be doing something right even if I don't fully understand how you do it.

And by the way I did some more testings and found out that exacerbating this resonant peak doesn't sound very pleasing when dealing with a higher gain setting that what I'm used to (I can live with that though as I very rarely use this kind of tone).

Thanks for the answer.
Rest assured I do think I have more to learn from you than you from me. 
Interesting point you have... and presented like this I fully agree with it: I do think as a general rule high Q band cutting is often better than high Q boosting.

But:
My preamps setting are often around the onset of clipping and as a consequence I try to maintain the other rule of thumb in my thinkings: Every filtering before the preamp (or first clipping stage) serves only the purpose of shaping the response of the clipping. Predicting how this will affect the clipping is very difficult as highs ride on lows (the assumption that pretend we can treat each frequency separatedly when thinking about it is an over simplification that might not work very good). Currently, even if this oversimplification works a bit to grasp the concept, it doesn't replace to me fiddling with any possibility before the clipping stage and hearing what happens. And my hears tell me both my guitars sound better (especially for clean to moderately overdriven tones) when buffered at a 3Mohm input than straight into the amp (which are more like 1Mohm if I remember correctly).

Well, as you say, I still got a lot to learn, and I really appreciate your views on this. Confronting different views does help learning things.

Quote from: phatt on April 19, 2013, 09:08:22 AM
Thanks QReuCk and Roly,,
I guess my reply would be, ok try it suck it and see?

Yes you can up the Z if you want but you will likely run into trouble trying to balance the clean sound which will then have the hump as well as a lot more treble ,,which is EXACTLY what you Don't Want for this type of sound.

This mismatch is what sends the novice round the twist (did for me ) because quite obviously a lot of modern amps have way more bandwidth than is needed for rock guitar tone and finding the balance between the clean sounds and OD sounds is hard to balance even for professionals.

Disclaimer: I do play with multi chanel amps that have separated EQ for each chanel...

And as far as bandwidth is concerned I do think you can have a big part of the benefits of presenting a high input Z to your PU's without suffering all the troubles: I don't know exactly what physical phenomenon it is linked to, but if you allow your PU's to resonate and filter out the excessive high end, you will still have the rich sound of the attack (heard cause these harmonics are on a very different octave than the root so they don't need to be at the same amplitude) rapidely decreasing into a more filtered sound (high order harmonics from the instrument do fade pretty quick). I won't say it sounds amazing with very high gain, but for clean or for moderate crunch I think it sounds pretty cool, especially if you attack quite heavily with the right hand (oh and don't set the pick ups too close to the strings, nor the strings too close to the frets, these things need some air to vibrate).

Well that's what I came up with after a few tests with commercially available boxes, but it might not fit perfectly another player. Trouble is: you have to think your tone from one end to the other. One of these ends being the player himself, it's not easy to come up with a do-it-all solution.

Quote from: Roly on April 16, 2013, 09:17:43 AM
http://www.till.com/articles/PreampCable/

'tho I'd be more inclined towards a Source follower, but the thing is, presented with a very high Z the natural pickup resonance isn't damped and this makes it sound richer, this...

That's what a good buffer is made for: present a very Z to the pickup while feeding the following circuitry with a more manageable low impedence signal.

Edit: Actually typed too fast, as in "before reading your (very informative) link". Anyway, I do think a good buffer at the input of the phabb zone will do exactly that, provided the first guitar cord and contacts are of very good quality.


Nice sound clip by the way.

As far as I know, you got +1 chip point anytime someone click on the [informative] button and -1 anyone click one [useless], the later of which doesn't seam to happen very often.

Is my post informative, or is it just a blatant try to obtain some credit from a post totally unrelated to the original topic?  :duh

Back on topic, I see no more to add to what has already been said. Could be interesting to compare the full frequency response of the two makes of speakers your comparing (not only the rated efficiency, but the full curve for each speaker, and also the measurement process used to generate them, which can vary a lot from one manufacturer to another).

To be heard, bass notes have to be at a considerably higher power. That's why the average bass player uses an amp 5times more powerfull than the guitarists he plays with.
They also generate a higher signal amplitude, which might push the speaker into its excursion limits. That's the main concern when plugging a bass guitar into a guitar amp. If it's just for training at home, you can get away with cutting a lot the bass bands of the amp's tone stack to prevent damage and avoid playing too loud.
Another one is that depending on the circuitry, your amp itself can enter into occillation if driven hard with frequencies lower than what it is designed for.

On another hand, a fairly high number of guitarists do plug a looper stompbox with integrated rythm box in it into their guitar amps without any troubles. These rythms sometimes contains very low frequencies (but they are recorded and compressed, which is a different matter than an uncontrolled live instrument.

Phabb, not sure it is what the OP wants to achieve here. My english is not that good so I might be mistaken, but I think he wants the harmonics of the overdrive sound to continue being generated when the note decreases. That's exactly what tube enthousiasts DON'T want to happen (they usually want the harmonics being generated only when feeded with strong signal and prefer to be able to control the amount of distorsion from the volume pot of the guitar). Here the OP for personal taste wants the oposite and I think that's fine (colours and tastes, you know...).
Bad news is that the way clipping works is input volume sensitive. So when the note fades, the clipping also fades. This is not that much noticeable when using a lot of gain, but when using a slight overdrive you clearly here it.
Two ideas here using a pre-EQ then the tone stack of the amp:
1° bass boost a lot with the pre-EQ use very moderate gain on the clean chanel then boost the highs/high mids on the tone stack. This will clip the lowest harmonics and fundamental a lot, producing a very noticeable fuzz that doesn't need a lot of gain to be interpreted by your hears as fuzz=> as the fuzz is noticeable even at low input volume, you'll here it a bit longer when the note decreases.
2° try the opposite: cut the bass bands with the pre-EQ, boost a bit the mids to high mids and cut the highs above 3KHz, you don't need them to compete with the harmonics your preamp will generate. At the preamp, you can get away with quite a lot of gain, cause you prevented the bass bands to clip too much (they are not clipped) and the mid bands generate harmonics that do not compete with the high harmonics from your instrument (cause you did cut them at the pre-EQ stage). You will then have a lot of compression but not that much fuzz, except when playing very harmonically rich chords (like 9th or 13th). Use the tone stack to adapt your averall tone and reemphasise the bands you did cut before the clipping stage.

Decide what you like best and fiddle with both the pre EQ, gain and tone stack to obtain what you are after. You might find a few new sounds you like, even if they are not exactly what you were after.

Pre EQ can be anything from trying different pickups/pickups configuration, any coloured booster or a stompbox equalizer (some prefer parametric ones, but graphical ones can do the job and are usually easier to find).

Hope that helps a bit.

I happen to be the happy owner of another Envoy 110 from 1995.
Although I recently bought a Tech21 Trademark 120 which is even greater for my band, I still use the Peavey when I don't want to carry the big stuff, and when I want to amplify my retro-fitted passive piezzo nylon accoustic.
With the stock speaker, it has a great transparent clean chanel.
From my experience, this amp benefits a lot from pre-EQing/clean boosting/buffering (any pedal format EQ will perform these 3 functions at the same time if you place them between the guitar and the amp as you're forced to do anyway with the Peavey that doesn't have an effect loop).

With your criteria, I would definitely go full analog SS or dare I say hybrid design (not convinced with the gain in tone though, but as they usually can be sold for a slightly higher price point, manufacturers tend to pay more attention to speaker selection in these cases than with 100% SS, and a well placed 12 AX7 might have some technicall interest).
From what I gathered, you could like:
- Roland Blues Cube 60 112 (don't bother trying the cube60XL, which is a really different design, only the blues cube is analog and almost universally praised for its clean tone)
- Tech21 Trademark 60 112 (beware that each chanel has its own medium, but bass and trebble are in the master section, which might not be that good considering chanel one can either be too bassy or to bright depending on the position of the bright button)
- Peavey Bandit 112 (not super standout clean on its own, but drive it with a slighly boosted M shape or frown curve EQ and hear what happens)
- Hugues and Kettner Edition Blue 60R (very nice clean tone)
- Some older SS Fender (don't remember the exact name, but I tried a SS 50W with one 12' speaker that did sound decent - stay away from frontmans though, they are really not on par with older SS models)
- Laney LV100 (which is really a 65W) and LV200 (same with hybrid design)

As far as tubes are concerned, I think the Peavey Valveking might fit your criterias, as would do a Laney VC30 if you can source a used one in your area.

Quote from: tomographs on November 06, 2012, 03:17:17 PM
Thanks for your in-depth responses guys, it's very much appreciated.

I wrote the questions making the assumption that tube amplifiers were largely considered to be the benchmark of a quality guitar sound, and that other amp designs essentially emulate the tube sound and response. If you think that's a false assumption than that's fine, and useful info for me. I certainly overlooked the fundamental differences in opinion amongst different forum communities - apologies for that.

Once again this is very useful info and I'll keep you all posted as the project progresses.

If anybody else has any opinions, I'd love to to hear them - thanks!

I'll voice a quite different opinion than Roly here: This asumption might be quite valid as far as marketability is concerned, but to my hears and without the notable exception of Kemper, SS gear that as been succesfull almost never is a true model of a specific valve amp. They sure try to reproduce some generally well accepted part of the behaviour of tube amps, but the good ones generally can't be looked at tries to exactly match one specific amp tone. They usually provide through various knobs and option a range of tones from witch some can approximate roughly what can be heard with various tube amps.

Not sure if I explain correctly, but if you take some of the well accepted and commercially available analog SS amps (think transtube, Tech21, etc...) the starting point is often to try to emulate the behaviour of tube amps, but admittedly or not without totally negating good aspects of SS gear (volume scalability, transparency against what instrument you plug into them, etc...).

Usually entry level DSP based products have a problem with transparency. I'm not an expert, but that would be logical for me that either the software (if not enough work is put in it) or the hardware (if undersized for the level of performance optimization vs complexity the software has) needs heavy filtering of the input signal to work properly, meaning, that all the subtle harmonics resulting from the delicate combination of sensible playing touch, strings, pickups might be lost in the process of feeding the software with something manageable for the processor.

As far as ergonomics is concerned, with the footswitchable 3 channels (highly configurable with independant character, drive, level and EQ controls), reverb and master boost of my trademark120 , the reactions of it to guitar volume pots level change and playing variation + a pre EQ stombox, I already have a lot more than what I do really need. Add to this the joker of a footswitchable stereo effect loop, and the fact you can get those things pretty cheap used thanks to the tube fashion, and you jump quite quick on the conclusion a DSP modeller would have to be darn good and inexpensive to convince me.

There are success stories in the DSP area though, but I fear this market is either limitted to semi-professional market (think Axe-FX, Kemper, Eleven Rack, etc...) or to entry level products (think Line6, Roland/Boss, Fender Mustang line, Vypyr from Peavey, Vox's take on that...).
For some reason, the presence of some glowing glass in the unit seams to help sell some of them at a bit higher price.

Just a though here: I just have bought a Trademark 120, which is based on the GT2 circuitry as far as preamp is concerned (but the cab sim is only active on the dedicated "sansamp" output, and as it's a combo supposed to work by itself, it has 3 bands active EQ).

First thing is either to feed a Hifi power amp and flat response speaker with the cab sim on, or bypass the cabsim part of the sansamp and drive a power amp and guitar speaker.

One other thing I noted is that the tweed voicing has a tendency to produce weak sound on the light strings (highE-B-G) compared to the other voicings. As a consequence, it needs (and I mean really needs) some EQ tweakings. Don't be mistaken, to add body to these strings you need both more trebble and more mids. So back off the bass a lot on the GT2 when using the tweed voicing or put an external EQ, especially if you are using a guitar with vintage humbuckers (less of a problem with active pickups or single coils).

Hope that helps even if I'm not able to advise on technical stuff.