komet for clean sound only?

[pamaz67]

Hi guys.
Probably this is not the right place, 'cause TW and Komet are "rock/blues addressed amps.
In any case a friend asked me to build a komet clone for him and when i first powered it up i was amazed by the incredible clean sound this amp can deliver ( before the excellent ditortion of course). Think about the fact that i was able to get some excellent jazzy sounds with an es175.
Unfortunately the amp is not anymore in my hands so i cannot make any test .
So I'm wondering if any of you has ever thought to use the komet design as a base for some mods ( first thought is to put a 12au7 or at7 int the pI for example) in order to get a complete clean amp .
Pls share your experience if you have any.
Thanks
Paolo

[Darkbluemurder]

Well - if this is not the right place which is???

If I read the information in this forum correctly then all 'wrecks - besides being great rocking machines - have also an excellent clean tone up to the point where overdrive sets in. I understand the quality of the clean tone in this style of amps comes from the harmonics which are also present in the clean tone.

Keep in mind that a blackface Fender Reverb amp has also 3 gain stages like the Express and the Liverpool. The main difference is that the 3M3/10pf reverb mix resistor throws away a lot of gain and so does the 50k intensity pot in the vibrato circuit. The Wrecks do not have either of these thus they have more gain. The use of a 12AU7 or 12AY7 would definitely clean up things further.

While I did not yet have the opportunity to play any wreck based amp I am going to experiment with adding a third stage to my modded Bandmaster Reverb. Currently it has only 2 gain stages (think BF non reverb amps) and is a very clean amp - which is fine to me since I use pedals for my OD sounds (to avoid the "please turn down"-comment). But I generally feel that an amp cannot have enough harmonics - whether in clean or overdriven mode.

[pamaz67]

This is not the right place in the sense that most of the people here and in the dumble forum is searching for overdrive tones.
I'm searching for the definitive clean sound and i can say that both dumble based amps , than the komet ( never had the chance to test a tw) are probably the best clean amps I've listened to (and played), each one with very different voicings , but with an uncomparable harmonic content that i've never heard in anything else. Keep in mind that I've been working for a while for the italian importer of brands like fuchs, bogner, cae, budda, etc.. and i've had the opportunity to test and service most of these amps.
Some of them are impressive, but none of these have got a clean sound good like a komet, or like a well built dumble clone. At least to my ears.
And is not just a matter of tone, but also the pick response of the komet is incredible. Most of the times i feel like all the other amps are "SLOW" stuff.
I would like to "clean up" the komet, leaving unaltered the harmonic content of the original.
bye
paolo

ps: the komet clone I've done uses some german shinrock transformers. Tumbs up for the quality/price ratio for these. they can pair the Mercury quality at a very low price ( at least in Italy).

[MKflo84]

Hello pamaz67

I'm interested in the same thing : I'm looking for the perfect amp, which would have a perfect clean sound and a perfect overdriven sound (think Knopfler).
I've build several amps in the past, and I wanted to try a JTM45 clone to see if it suit my taste. How would you compare the Komet to the plexis ? I'm looking for a quite mid scooped sound, and quite bright too which can get dirty.

Last question, I've build an ampeg B15N clone with Hammond trannies (both OT and PT) and the result is excellent. What do you think of this brand of trannies ?
Thanks,
Florian

[pamaz67]

I've built a very nice amp based on jtm 45 with some modification on the supply, with bright and normal input connected simultaneously, and with Mercury irons, and probably is the best clean amp for using pedals I've ever tried.
It's a much darker tone than the komet, but with an incredible harmonic complexity. It works perfectly with Humbucker PU and with a sort of tele I use, but I think the komet is way better with a strat style guitar.
I think there is no universal amp, so probably any guitar needs a different amp. Komet to me is incredible with a strat style axe.
In any case I'm always talking just of CLEAN sounds.
Regarding Hammond trannies, I've used them just once in a SLO clone (UGLY amp to my tastes) and they are quite good. IMHO it's a matter of setting up the feedback loop to "tune " the amp to a certain Iron, so most of the output transformers are usable.
Ciao

Paolo

[lastwinj]

try removing the clipper stage. should clean it up a decent amount, bive you more headroom.

germ

[Darkbluemurder]

I guess by "clipper stage" you are referring to the third gain stage with the 10k cathode resistor. If you remove that you are back to 2 gain stages just like an ODS clean channel or like my Bandmaster is wired right now. As I said this is indeed a very clean amp. Of course it's not an Express or Liverpool styled amp then. I guess however Paolo was interested in whether the clipper stage is worth adding due to the extra harmonics it may provide even to the clean sound. Such extra harmonics may still be there with a lower gain tube.

[pamaz67]

Darkbluemurder you are correct.
Taking off the third stage for sure will impact on the harmonic content, modifying in a deep way the voicing of the amp.
My aim is to leave unaltered the voicing, lowering the overall gain and leaving the dynamic response as the original komet desig call for.
Usually going to a lower voltage gain/higer current capabilty triode on the PI leads to an enhanced sound richness. This at least is what i would expect, but have not had the chance to test.
Thanks and bye
Paolo

[Darkbluemurder]

Paolo,

Check out www.alessandro-products.com. The Italian and the Redbone look like cleaner amps based on the Express topology, using 6SL7 and 12AU7 tubes. There is also a schem of the Redbone on schematic heaven. Never got to play through one, unfortunately. Approx. one year ago I saw a Bloodhound (3 12AX7s in the preamp, closest model to an Express) on German ebay but didn't buy it for the fear I wouldn't play it (too loud at home and in the country rock band).

Cheers Stephan

[pamaz67]

thanks a lot for the advise. I'll better check Alessandro stuff that I know mostly for the headphones products .

Ciao

Paolo

[Darkbluemurder]

I looked a bit more in detail at the Alessandro Redbone schematic on Schematic Heaven. It has 3 identical gain stages (100k plate resistors, 1k5/25uF cathode). All that is between the 2nd and 3rd stages (both 12AU7) is a 0.022uF cap and a 150k resistor to ground, i.e. just like a wreck.

The only thing that confuses me is the 3rd stage's plate resistor bypass cap of 5000pf. I would expect that this cap introduces a severe high frequency roll-off which would rather kill the nice harmonics we are looking for. At least that would be the case with a 12AX7. Maybe it is different with a 12AU7 (lower miller capacitance)?

Or the designer wanted the stage to add low end. But then it seems weird that the low end is limited through the small PI input cap of 500pf - 1000pf.

Any comments?

[pamaz67]

i will check it during the weekend and report my thoughts asap.
Thanks
Paolo

[pamaz67]

at first sight I cannot explain why the Alessandro have such capacitors. they seem to be really weird values . probably the only rule is to mount a ckt and test it.
In any case FWIW I share the choice of octal tubes that are a leap forward compared to the 12afamily tubes in terms of harmonic richness. This is something I've already verififed also in Hifi gear, wHere 6s family tubes are really appreciated for their characteristics.
I'm thinking of a turrett breadboard who can accomodate both octal than noval tubes, while sharing the komet pre circuit, just to make tests for finding the optimal value arrangement for the amps.
has anybody made such a tool?
Ciao
Paolo