Clipping diodes

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tonefreak
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Clipping diodes

Post by tonefreak » Sun Mar 08, 2020 6:19 pm

Does anyone know if the JVM or JVMJS uses clipping diodes or other solid state clipping?

rockat
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Re: Clipping diodes

Post by rockat » Sun Mar 08, 2020 8:44 pm

No they definitely do not! Hope that helps.

Casey_Butt
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Re: Clipping diodes

Post by Casey_Butt » Thu Mar 12, 2020 5:01 pm

The entire audio path, including the effects loop, is all tube.
_ JVM410H: "Blackface" Clean channel, "Plexi" Crunch channel, "Dual Rec" OD2 channel, 3rd stage bias pot with switchable 100nF bypass cap, switchable 470k/470pF "treble peaker", OD1/2 Orange and Red extra gain pot, signal boost into power amp, PI voltage set to 2203 levels, 5H choke w/ 50uF on screens, -ve feedback pot.
_ Marshall 2203/1959 clone - switchable (with FX loop, resonance control and -ve fb pot) built from a Peavey Windsor 'donor' head
_ Fender Deluxe Reverb clone head
_ ADA MP-1, ART Power Plant, Tech 21 PSA-1
_ 1960A cab w/ Celestion G12-65s and G12-75Ts in X-pattern, Peavey JSX cab with Celestion G12M's (UK 6402 cones)
_ Fender Pro 185 (rebuilt) - open back 2x12" with Jensen C12Ks

okgb
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Re: Clipping diodes

Post by okgb » Thu Mar 12, 2020 6:14 pm

Although a diode clipping mod should be considered , ala the Jose mods, jubilee and 2205 !
Amps JVM 410H [too many mods to mention ] '73 50w lead, 70's vibrochamp , mesa mkIII U.S. Vox pacemaker
Rock , pop rock & Blues style's mainly played
Gtr's Musicanman " Luke " wolfgang [ carved top w pearly gates ] Hondo lazer , Warmoth strat
Fx t.c. 2290 , Lexicon tc verb
Pedals tbone plexi , t.c. chorus , various handmade & usual suspects t.s. , zen , CB wah ..........

Andy
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Re: Clipping diodes

Post by Andy » Thu Mar 12, 2020 8:04 pm

I agree the more sonic palates we have the better !
|----- if this forum helped you, pls donate to keep it alive -----|
::: JVM410 head,modded:- Hammond 5H choke, 2 tubes pulled, 37.5mv bias :: Caseys Mods :- Plexi cap, -ve feedback, Dual Rectifier, Blackface, 1 wire Randy Rhoads, Plexi, Metaled Out ModPI Boost, OD Channel Gain Reduction Mod
::: AFD100, DSL100W head (no C83), Fender Champ 12
::: 1960AV 2xgreenbacks 2xG12H30, homemade 2x12 cab 2x Celestion Golds (100W)
::: Gibson Les Paul Standard, Dimarzio SD bridge Pup,Standard neck Pup.
::: Tokai Strat with Dimarzio SD, Epi SG-400 Iommi, Hondo Les Paul, Alhambra Acoustic fishman Pup
::: PodXTLive, Vox V848 Clyde McCoy Wah Wah,

It's better to fail in Originality than to succeed in Imitation ...

okgb
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Re: Clipping diodes

Post by okgb » Mon Mar 16, 2020 5:20 pm

Shouldn't be too hard if we start with copying known circuits, then the snob police will arrive to make sure we pick
exactly just the right diode, the jose mod seems to be transistors [ used as diodes by using one junction , although some argue it's the internal protection diodes that get clipped ] before the tone stack, basically add some diodes and a switch to ground , the jub rthym clip is a single diode
in the cathode. I gotta fix my JVM first bad output tube took something out , before I can get to this.
Amps JVM 410H [too many mods to mention ] '73 50w lead, 70's vibrochamp , mesa mkIII U.S. Vox pacemaker
Rock , pop rock & Blues style's mainly played
Gtr's Musicanman " Luke " wolfgang [ carved top w pearly gates ] Hondo lazer , Warmoth strat
Fx t.c. 2290 , Lexicon tc verb
Pedals tbone plexi , t.c. chorus , various handmade & usual suspects t.s. , zen , CB wah ..........

Casey_Butt
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Joined: Mon Nov 02, 2009 7:09 pm
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Re: Clipping diodes

Post by Casey_Butt » Tue Mar 17, 2020 12:00 am

It's an interesting idea. Diodes to ground (hard clipping) tend to be harsh unless there's some filtering to tame those high-order harmonics. It's great for picking clarity, but it isn't really tube-like. IMO, diodes in a feedback configuration (like in some some Boss pedals) can be made to clip much more preamp tube-like, but then there's the nuisance of voltage levels - the voltages are just so high in tube preamps.

I remember reading an article where listeners had to guess whether a preamp was solid-state or tube and they couldn't consistently correctly identify which was which, but IIRC listeners could identify tube power amps. Preamp tubes don't compress like power tubes, they clip much more directly (for want of a better term), so it isn't too hard to mimic that in solid-state.
_ JVM410H: "Blackface" Clean channel, "Plexi" Crunch channel, "Dual Rec" OD2 channel, 3rd stage bias pot with switchable 100nF bypass cap, switchable 470k/470pF "treble peaker", OD1/2 Orange and Red extra gain pot, signal boost into power amp, PI voltage set to 2203 levels, 5H choke w/ 50uF on screens, -ve feedback pot.
_ Marshall 2203/1959 clone - switchable (with FX loop, resonance control and -ve fb pot) built from a Peavey Windsor 'donor' head
_ Fender Deluxe Reverb clone head
_ ADA MP-1, ART Power Plant, Tech 21 PSA-1
_ 1960A cab w/ Celestion G12-65s and G12-75Ts in X-pattern, Peavey JSX cab with Celestion G12M's (UK 6402 cones)
_ Fender Pro 185 (rebuilt) - open back 2x12" with Jensen C12Ks

okgb
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Posts: 707
Joined: Fri Apr 29, 2011 1:50 pm
Location: The Great White North-Winnipeg

Re: Clipping diodes

Post by okgb » Wed Mar 18, 2020 1:34 pm

hard clipping within tube clipping, I believe Freidman calls theirs a saturation control. for marshall the first instance i know of is the JCM 800 2205 early 80's , I owned a silver jube and liked it before knowing it used diodes, both in that amp seem to sound good, the lead channel using a diode bridge
to ground [ same as the jmp1 rakmount preamp ] and the single diode in the cathode for the rythm clip

I would have thought throwing a trimmer in between the signal & diodes could tame it but I don't see that in other circuits, however jack Orman suggested using a pot to bypass diodes to ground in pedals, so perhaps that would work here. still need to decide where in the circuit to place it.

For the Casey level people [ which ain't me ] somewhere around the Zen drive pedal multiple diode combinations started appearing in custom pedals
the diode bridge used in marshalls has a 5th diode connecting two points together, some pedals have them connected in the middle
Amps JVM 410H [too many mods to mention ] '73 50w lead, 70's vibrochamp , mesa mkIII U.S. Vox pacemaker
Rock , pop rock & Blues style's mainly played
Gtr's Musicanman " Luke " wolfgang [ carved top w pearly gates ] Hondo lazer , Warmoth strat
Fx t.c. 2290 , Lexicon tc verb
Pedals tbone plexi , t.c. chorus , various handmade & usual suspects t.s. , zen , CB wah ..........

RockmanCentral
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Location: Central Florida

Re: Clipping diodes

Post by RockmanCentral » Thu Mar 19, 2020 1:12 am

Casey_Butt wrote:
Tue Mar 17, 2020 12:00 am
Preamp tubes don't compress like power tubes, they clip much more directly (for want of a better term), so it isn't too hard to mimic that in solid-state.
I did try adding some zener diodes to my HJS (or, could have been the regular JVM, don't recall) but I could never get the right zeners to match the voltages correctly to get the clipping. I ended up deciding that the amp sounded great without it, so gave up on it.

One thing I like about tube amps is that you can use the preamp tubes to clip the lows and mids and then drive the presence really hard to clip just the higher frequencies using the output tubes. This seems to really help rhythms cut through even in a busy mix. Backing off on the volume cleans up the highs easily too.

BTW, the Rockman used both diode and LED clipping for it's distortion. The signal is heavily compressed at the input to flatten out the response, then shaped with EQing to emphasize the right frequencies for clipping by the diodes/LED's, then EQ'd again for the cab sim. Which makes sense since Tom Scholz was a big fan of output tube compression and clipping.

On a side note, before he sold the Rockman line to Dunlop Mfg, Tom had plans to release a tube based Rockman Sustainor. It's such a shame that he didn't do it because I bet it would have sounded pretty amazing. I've always been meaning to try using some white or pink noise to check the exact filtering used on the Rockman right up to before it's clipped, then get the filtering used after the clipping, and then applying that pre and post EQing with a tube amp to see how it would sound.
Gear:
Marshall JVM 410HJS - -ve Feedback
Kemper Profiling Rack
Two Notes Torpedo Live
Marshall 1960 HW Stack - G12H-30's
Marshall 1960 Lead Stack - G12T-75's
Rockman Stack with Rev 20 Sustainor
Rockman XP212, XP100a
Echoplex EP3 - Hyperspace Pedal
Gibson Collectors Choice #10 Tom Scholz 68 Les Paul Goldtop
PRS SE 24 Custom Floyd - Sustainiac, DiMarzio Super Distortion, Graph Tech LB63 Floyd Rose, Acoustiphonic preamp
Jackson Dinky Reverse - Sustainiac, DiMarzio Super Distortion
Epiphone 68 Reissue Les Paul Goldtop

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