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Quilter Bass Block

Discussion in 'Amps and Cabs [BG]' started by Tjreclus, Apr 18, 2016.

  1. Tjreclus


    Feb 28, 2016
    Hello guys, I usually just lurk on here, but I just found out that Quilter has passed FCC regulations and the bass block is now in production!
  2. SnoMan

    SnoMan Words Words Words

    Jan 27, 2001
    Charleston, WV
    First time I've heard of this company. Have any other info to share? I don't see mention of the bass block on their website.
  3. 808P123


    Mar 25, 2015
    Quilter is popular with pedal steel and guitar players Pat was one of the founders of QSC.
  4. basscooker

    basscooker Commercial User

    Apr 11, 2010
    cincy ky
    Owner, Chopshopamps.com
    Info or link? Specs? Color me interested.
  5. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    I've used the fourth-generation prototype a few times (I have a connection). It's quite powerful. I was concerned at first ver the dearth of EQ knobs, but the contour controls are pretty versatile and within a couple minutes i was able to dial in a really nice tone.

    Now I don't know whether to keep my cab (EX B-1150M, a big 15" 2-way) and get a Bass Block or keep my pre and dbx comp/lim and get a powered loudspeaker, like a K10 or K12.
    Red Planet likes this.
  6. walterw

    walterw Supportive Fender Gold Supporting Member Commercial User

    Feb 20, 2009
    could this at last be the reasonably-priced high-power "little black box" bass power amp we've all been waiting for?
  7. Primakurtz

    Primakurtz Registered Nihilist Supporting Member

    Nov 23, 2011
    Denver, Colorado
    It could well be! Their guitar amps are really good. Made in the USA, too.
    seang15 likes this.
  8. steelbed45

    steelbed45 TRemington Supporting Member

    Feb 23, 2011
    Nolanville, TX
    That's great news - I remember the original interest thread on TB.
  9. Passinwind

    Passinwind I am Passinwind and some of you are not. Supporting Member Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    My understanding is that it's an integrated bass amp, not a dedicated power amp.

    Just curious: what would you consider a reasonable price for an 800-ish watt monoblock power amp?
    mbelue likes this.
  10. steelbed45

    steelbed45 TRemington Supporting Member

    Feb 23, 2011
    Nolanville, TX
    Is it evolved past the pic that Bob posted of the prototype he was trying out in 2015? My main concern with that version was I only saw instrument inputs - no line level on the back.

    If this whole thing started out as a thread on getting a dedicated small form power amp built, but ended up as just another bass amp, I'd be bummed - not gonna lie.
  11. Passinwind

    Passinwind I am Passinwind and some of you are not. Supporting Member Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Let's ping @Bob Lee (QSC)
  12. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    I'll have to drop by over there and see!
    Tjreclus and Passinwind like this.
  13. fast slapper

    fast slapper

    Dec 11, 2001
    Fresno, CA
    Some tech details about the amp.

    - The depth control is a 24db per octave cut or boost below 100hz. This will add depth without getting muddy or tighten things up without getting thin. There is a gentle rolloff below 20hz.
    -Slow rolloff above 12k extending over 20k.
    -The master volume control actually limits the power delivered to the speakers as specified by the amount on the knob.
    -Limiter is described as very transparent and bottomless. Curious to hear this in person.

    Sounds like it should be a winner for tone purist. Will be trying one when available.
    elkkid2, Killed_by_Death and Tjreclus like this.
  14. domonic


    Aug 22, 2014
    Is it soup yet ??

    (when is this thing coming ??)
    MYLOWFREQ likes this.
  15. Type-55


    Jul 20, 2000
    I'm in
  16. teemuk


    Mar 1, 2011
    If it's similar to their guitar amps the power amplifier actually models some most distinctive characteristics of a generic push-pull, class-AB tube (power) amplifier. So depending on design it may introduce some degree of "coloration" to the signal reproduction chain, even when not particularly overdriven. At least their related patent describes a scheme to model high output impedance, and resulting weaker "damping factor", of generic tube (musical instrument) power amps, which in turn introduces "non-linearity" to overall frequency response because gain of power amplifier with low damping factor is effectively somewhat dependent on load impedance that varies with frequency. Frequency-dependent gain characteristics will enhance all resonant frequencies and frequencies that otherwise present a higher-impedance load. Usual effects are low end boost due to speaker's resonant frequency near their low frequency limit and gradually increasing enhancement of upper mid-range and higher frequencies due to inductivity of voice coils in general. Crossover networks, piezo tweeters and alike will introduce more "complex loads" where load impedance may peak at various different frequencies. Power amplifier with low damping factor will enhance all such peak frequency bands .

    Additionally the patent describes means to emulate certain ovedrive characteristics that - at least by generic acknowledgment - are traditionally introduced by such aforementioned tube power amps: Clipping distortion is similarly somewhat gradual and "soft", and the dynamically changing clipping threshold due to "power supply sag" characteristics is also effectively modeled. Power tube grid overdrive and resulting dynamic effects like bias shifts, related introduction of crossover distortion under sustained loading, and related "blocking distortion" characteristics are also modeled.

    So if it's anything like the design in their guitar amps it should be a power amplifier with characteristics and performance very similar to aforementioned tube (musical instrument) power amps. ...Particularly those aimed for guitar rigs because many "classic" tube power amplifier designs for bass amplification actually tried to - in great degree - reduce or eradicate effects of many aforementioned characteristics, particularly "sponginess" of amps with sagging power supplies, "fizzyness" and "farting out" of amps that introduce bias shifting during sustained overdrive, and excessively enhanced low end, overall signal "coloration", "flabbyness" and poor transient response of power amps with low damping factors.

    I realize it's solely a matter of preference, but many bass guitar players - especially those employing more "modern" playing techniques and tonal landscapes overall - tend to prefer more "sterile" power amplification (whether tube or SS) when it comes to bass guitars. Distinct warmth, coloration, distortion, dynamic variance et cetera that works when you amplify an electric guitar may be too excessive and disturbing when one amplifies a bass guitar. The trend to prefer solid-state amplification is much more prominent with bass guitar players than it is with guitar players, and to very large degree due to generic "solid-state" characteristic of having no particular distinct characteristic, just amplifying the signal accurately and without coloration. Designs with "stiff" power supplies and high damping factors introduce characteristics perhaps more favourable to bass amplification, like overall frequency response linearity (even to complex loads like x-way bass cabs with passive X-overs) and improved definition of signal transients.

    So, no disrespect to Quilter and his/theirs designs intented, but if one has interest in these amps because they are solid-state (and because traditional "linear" solid-state-ish performance is therefore expected), then it might be worthwhile to acknowledge that these amps most likely are not quite similar to such but rather categorize under label of musical instrument power amplifier, which loosely means something along the lines of: "I'm actually a signal processor / effect unit disguised as a power amplifier, and I WILL color the signal while I amplify it. That's the sole purpose of my design.". So if your preference was actually higher fidelity, more linear and accurate signal production, - the solid-state cliché - then you most likely want to steer away from employing (power-amplifying) effect units that had totally different design goals. They made this solid-state amp intentionally perform similarly to certain tube power amps.

    On the other hand, there are bass guitarists who do prefer and enjoy such signal coloration effects, generally considered "tubey". For them these kinds of (intentionally signal-coloring) solid-state musical instrument power amplifiers offer characteristically similar alternatives to generic tube musical instrument power amplifiers. Yes, differences to generic, "Hi-Fi-er" power amp designs probably were somewhat underlined. But - IMO - this generalisation particularly applies to more distinctly guitar-amp-like designs. By its performance the Quilter power amp design, for example, is essentially more similar to classic vintage Bassman/Marshall power amp than it is to any classic tube power amp favoured by bassists, particularly anything even resembling the SVT. Keep in mind that classic tube power amp designs for bass guitars were - for good reasons - rarely too similar with classic tube power amp designs for electric guitars. But those are what Quilter's designs prominently "model". Not a bad thing at all, on contrary, and certainly more choices for bass guitarists overall, but just something to be aware of and keep in mind. Don't expect a Quilter amp to be a traditional solid-state amp. It's intentionally going to feature characteristics of certain tube power amps, which - however - some people do regard unpreferable in bass amplification.


    Back to the topic, master volume arrangement of Quilter amps is indeed also different to popular master volume arrangements that simply attenuate input signal to power amplifier while retaining a "fixed" output power rating. Such amps basically control perceived loudness simply by "having less to amplify" and their headroom limit remains fixed. The dilemma encountered, and already few decades old, is that if we want to use such power amp as an effect processor that intentionally generates harmonic distortion (and other associated effects) it must be overdriven past producing its rated output power, which is the point where the amp still introduces very low amounts of any harmonic distortion, and effectively that means the rig is often going to be operating at disturbingly and unacceptly loud volume levels.

    Reducing output power, or more particularly just the overall "headroom", amount of produced output power where signal is still amplified within the specs quoted by that "@ x % THD" - line, can shift overdrive to take place at lower perceived loudness levels. This is not a new idea by any means. It's basically the key operating principle of schemes like PPIMVs, current starved PIs, pentode/triode switches, user adjustable power supply voltages (e.g. "Power Scaling") and alike: Basically, instead of attenuating the input signal, reduce the rated output power at which harmonic distortion still meets quoted specs. For example: Instead of 1% of THD getting exceeded at 100 watts of output power, make the amp exceed that 1% of THD in the signal already when its producing merely, say, 1 watt of output power. Various different methods to accomplish that goal are legion, and if goal is to simultaneously achieve archetypal "tube power amp-ish" overdrive characteristics not all schemes even manage to capture every nuance of such performance in stunning great detail and realism.
    It may sound counter intuitive but Quilter's analog modeling circuit - albeit being entirely solid-state - for example, fairs much more realistic results in replicating performance and behaviour of overdriven push-pull, class-AB biased tube power amp than what any PPIMV or current-starved-PI -based design achieves using real, genuine vacuum tubes. Many dynamic effects overlooked or ignored by inherent nature of such circuit designs have been taken into consideration in Quilter's design and the overall result is therefore much more "realistic" than remotedly close attempts to model real tube power amp / power tube distortion by means of phase inverter distortion, which sounds very similar but lacks all related dynamic effects and nuances that explain great deal of touch sensitivity, feel, and warmth associated to tube amp overdrive. Note that such characteristics, however, may not neccessarily at all correlate with subjective preferences of what is "good tone" or even "tube amp tone", though.

    But yeah, Quilter amps call for "new" approach to handle loudness control, an approach again more traditionally favoured by those guitar players: Instead of decreasing overall loudness while retaining a fixed threshold of headroom, reduce that headroom and effectively distortion will appear at lower loudness levels. This is of course just another introduction of the age old dilemma of how to define musically useful concepts like "dynamics"; Is it amp's capability to accurately reproduce high signal transients without distortion, high dynamic range so to speak, or is it increased sensitivity to generate musical effects like harmonic distortion, or perhaps increased amount of "dynamic" characteristics within such effects?

    Compression, by definition, limits dynamic range of the signal and signal clipping distortion is form of compression. Then again, there are distinct effects in performance of archetypal push-pull, class-AB tube power amp circuit that are in many ways similar to expanding signal's dynamic range: Signal clipping compresses, but power supply sag can make envelope and amount of that compression very dependent on overall signal dynamics. e.g. Harder sustained overdrive automatically reduces output signal's amplitude, which in turn mimicks more pronounced envelopes of signals that do not have their dynamic range and crest factor reduced by signal compression. Crossover distortion from bias shift during sustained overdrive of power tubes is another dynamically variant effect that affects timbre of amp's distortion, effectively causing the amplifier to introduce and gradually shift between different kinds of patterns of harmonic distortion when ovedriven lightly, overdriven more heavily, and depending on time constants of that sustained overdrive condition. So it can again make the amp react more touch sensitively and "dynamically" to ovedrive even though the overdrive is inherently reducing signal's dynamic range by clipping compression.

    Popular trend in bass amplification has been, however, to favour moderately linear, high power amps, with "stiff" power supplies, high headrooms and minimal chances to overdrive even if exposed to signals with HUGE dynamic range. Such performance may even be essential when one employs "slap" techniques to play bass guitar. Low frequency harmonic distortion will also more profoundly than high frequency harmonic distortion introduce the kind of intermodulation distortion that usually doesn't fit too well to generic musical contexts so greater degree of linearity is required than from, say, guitar amp. IOW, amplifying bass signals in decent magnitude of "cleanness" requires more headroom than amplifying mid-range or higher frequencies because relatively lesser amounts of harmonic distortion are tolerable due to effects of IMD involving low frequencies. For example, many intentional "harmonic generation" and "distorting" circuits / effects for bass duties rely on distorting mid-range and higher frequencies only, which gives a bit of "edge" to the tone by enhancing higher order harmonic content. BUT if low frequencies were also distorted in similar magnitude the tone would become unbearable, muddy "farting" because IMD would rise alarmingly high.
    While guitar amps, especially when it comes to producing modern high-gain tones, can practically hi-pass filter at @1kHz in order to reduce IMD such technique seldom works in bass amplification. Reproduction of fundamental at full gain may not be neccessary for "strong" bass, but response that extends below mid-range definitely is. So strong, musically-pleasing, "clean" bass calls for greater output power than amplifying more mid-range oriented content.

    Additionally, seeming effects of expanding dynamic range with dynamically varying envelope characteristics of the overdrive is also very popularly considered as "squishyness", which can benefit a guitar amp of certain nature, but very rarely bass amp. Perhaps even contrary. Trend of popular features to include in bass amps have for years been built-in signal compressors and limiters (not dynamic range expansion) and "stiff" power supplies to guarantee authoritive, sustained and clean reproduction of bass. High damping factors are also popular preference due to resulting flatter frequency response to all kinds of loads, improved transient response, and tighter control of the cone movement. Solid-state guitar amps have for few decades popularly employed schemes that artifically decrease damping factor and therefore introduce performance more similar to that of tube amps. Implementation is trivial and very cheap, yet implementation of that feature to solid-state bass amplifiers have never enjoyed equal popularity. There must be a reason for that, which probably is very similar to reasons why many bass guitarists also prefer solid-state amplification over tube-based. And it's not just weight, size and cost, though they are admittably part of temptation.

    Anyway, what one prefers to employ as bass amplifier is naturally matter of individual and subjective preference. It is just generally interesting to see an intentionally "tube-ish" amplifier being introduced to market crowd that largely has not favoured too "tubey-ish" amplifiers. Whether they have realized that or not.
    TyBo, Garret Graves, Levin and 24 others like this.
  17. CharlieC

    CharlieC Supporting Member

    Aug 20, 2010
    New York, NY
    Thank you, this is a fantastic post. :thumbsup:

  18. domonic


    Aug 22, 2014
    WOW , I will have to read that dissertation a few more times !!!! Whatever magic mojo Pat is brewing in I love his gui**** amps and want to expose my hearing apparatus to his take on bass instrument amplification ..... WE ARE WAITING Mr. Quilter !!

    elkkid2 likes this.
  19. basscooker

    basscooker Commercial User

    Apr 11, 2010
    cincy ky
    Owner, Chopshopamps.com
    K.I.S.S. (Does anybody remember this?!?)

    -Small micro/half rack/ large pedal sized.

    -High power output @ low THD

    -Instrument and line level in

    -Hit the sub $400 price point

    Get rid of all that other stuff. HPF is cool, DI is great, tone controls are a bonus, but suddenly it just becomes another head. NOT what some of us want. Sure, it isn't the largest segment of the market. But there IS a market. And the power section is already ON the market. And somebody will make it sooner or later. Why not be the first?

    You don't need to impress other engineers with it. Just make it deliver reliable high power with as little THD as you can in a dependable, light, small and sturdy package. Leave the bells and whistles for Rev 2.0 when you make a head with the same power section in it for a higher price point. I just want a power amp that doesn't have to be put in a rack and doesn't have a preamp I'll not be using, but pay for.

    Flame suit engaged. Won't change my opinion on this one. Where is my black box? I ended up here at TB while looking for a MFR to make this near exact thing FOR ME TO SELL. Time after time told there's not a market, or that MI is too crowded for new products. At the right price point, this thing could become, IMO, much like the obligatory DI in the bag. You may not need it, but you have one with you for every gig. That seems like an awful lot of sales if gigging players view it as a great thing to have on standby with only a little space and a couple of pounds in their backpack. Nobody needed an Ipad before it came out. I think that product did okay.
  20. CharlieC

    CharlieC Supporting Member

    Aug 20, 2010
    New York, NY
    I am actually excited to hear what something like this could do for bassists!

    ... and who knows, perhaps the RETURN jack on the front let's one tap the clean power amp section alone for traditional SS (less the coloration)?

    JCooper likes this.

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