This is for those of you who are not scared to take a soldering iron to your amp, if this is not you, look away now :o
I'm not quite sure that challenge is the right idea to use here, but I've got this vague idea for starting this thread, tell us what you don't like about the sound of your amp. We'll look for the schematics, and suggest, preferably just one, but no more than four at one time, of components you can change, or wiring you can mod to improve the sound.
You make the change or changes, tell us whether it sounds better or not, and we can start the process again :)
Quote from: Hemisaurus on November 01, 2011, 11:19:36 AM
This is for those of you who are not scared to take a soldering iron to your amp, if this is not you, look away now :o
I'm not quite sure that challenge is the right idea to use here, but I've got this vague idea for starting this thread, tell us what you don't like about the sound of your amp. We'll look for the schematics, and suggest, preferably just one, but no more than four at one time, of components you can change, or wiring you can mod to improve the sound.
You make the change or changes, tell us whether it sounds better or not, and we can start the process again :)
Message Approved By Dunwich Amps. services available
i have a VTM 60. i want the high end to be less spikey.
Quote from: dunwichamps on November 01, 2011, 11:20:53 AM
Message Approved By Dunwich Amps. services available
Good, it will give us something to argue about, err I mean discuss ;)
Quote from: justinhedrick on November 01, 2011, 11:24:53 AM
i have a VTM 60. i want the high end to be less spikey.
http://www.webphix.com/schematic%20heaven/www.schematicheaven.com/newamps/peavy_vtm_120.pdf (http://www.webphix.com/schematic%20heaven/www.schematicheaven.com/newamps/peavy_vtm_120.pdf)
I hate this schematic :(
Justin remind me which input you use, and maybe give us some idea of your common settings.
Remove C4 or C9, you can also remove the bright cap on the gain pots.
Another fix could be making a FX loop low pass filter, its simpler, passive and not built inside the amp
Sounds like a good starting point, you don't even need a soldering iron, unless you want to replace the caps again :)
Low Pass Filter means Tone Knob, a pot with a capacitor and a couple of jacks.
Quote from: Hemisaurus on November 01, 2011, 11:35:59 AM
Sounds like a good starting point, you don't even need a soldering iron, unless you want to replace the caps again :)
Low Pass Filter means Tone Knob, a pot with a capacitor and a couple of jacks.
you could even built a simple little pedal which had some kind of passive EQ that could tame the high end not the hardest thing to do persay
treble peaking caps are the first place to pick at with modern amp with a lot of top end bite, along with bright caps on pots. Beyond that your talking about making some high end shunt caps on grid wires or plate resistors
Im going to recap my Butcher.
Would like to cut some of the highs. its a little too bright for me.
or maybe jsut do this to it.
http://www.davidsonamp.com/woodland_gallery/gallery_butcher.php
Quote from: rayinreverse on November 01, 2011, 11:42:30 AM
Im going to recap my Butcher.
Would like to cut some of the highs. its a little too bright for me.
or maybe jsut do this to it.
http://www.davidsonamp.com/woodland_gallery/gallery_butcher.php
http://music-electronics-forum.com/attachments/11449d1288300024-peavey-butcher.pdf
Remove C6, C3, C15, C16, Try doing this one at a time, seeing what you like
assumption is you are using the high gain input
Quote from: dunwichamps on November 01, 2011, 11:37:03 AM
Quote from: Hemisaurus on November 01, 2011, 11:35:59 AM
Sounds like a good starting point, you don't even need a soldering iron, unless you want to replace the caps again :)
Low Pass Filter means Tone Knob, a pot with a capacitor and a couple of jacks.
you could even built a simple little pedal which had some kind of passive EQ that could tame the high end not the hardest thing to do persay
treble peaking caps are the first place to pick at with modern amp with a lot of top end bite, along with bright caps on pots. Beyond that your talking about making some high end shunt caps on grid wires or plate resistors
What's wrong with changing the coupling cap values? Most modern guitar amps have them about a tenth of what they should be? I'd hit that after the bright caps, and before cathode bypass :) I was eyeing up C2,3,6,8,9 for replacement, but that was more than my four, but the bright caps are the simpler call.
Quote from: Hemisaurus on November 01, 2011, 11:48:05 AM
Quote from: dunwichamps on November 01, 2011, 11:37:03 AM
Quote from: Hemisaurus on November 01, 2011, 11:35:59 AM
Sounds like a good starting point, you don't even need a soldering iron, unless you want to replace the caps again :)
Low Pass Filter means Tone Knob, a pot with a capacitor and a couple of jacks.
you could even built a simple little pedal which had some kind of passive EQ that could tame the high end not the hardest thing to do persay
treble peaking caps are the first place to pick at with modern amp with a lot of top end bite, along with bright caps on pots. Beyond that your talking about making some high end shunt caps on grid wires or plate resistors
What's wrong with changing the coupling cap values? Most modern guitar amps have them about a tenth of what they should be? I'd hit that after the bright caps, and before cathode bypass :) I was eyeing up C2,3,6,8,9 for replacement, but that was more than my four, but the bright caps are the simpler call.
Changing coupling caps is another option, however this is also going to change the structure of the gain more IMO, as letting in more low end will get you some more wooly clipping. Nothing wrong with that. treble peaking caps and bright caps are just simpler to eliminate and you do not have to then buy 400-630V replacement caps for the coupling
the reason coupling caps are so small in modern amp is to avoid blocking distortion and excessive grid current since they never fucking using grid stoppers!!!
Quote from: dunwichamps on November 01, 2011, 11:46:20 AM
Quote from: rayinreverse on November 01, 2011, 11:42:30 AM
Im going to recap my Butcher.
Would like to cut some of the highs. its a little too bright for me.
or maybe jsut do this to it.
http://www.davidsonamp.com/woodland_gallery/gallery_butcher.php
http://music-electronics-forum.com/attachments/11449d1288300024-peavey-butcher.pdf
Remove C6, C3, C15, C16, Try doing this one at a time, seeing what you like
assumption is you are using the high gain input
yes using high gain input. I was thinking of changing values of those caps, but you think just remove all together?
Quote from: rayinreverse on November 01, 2011, 11:50:40 AM
Quote from: dunwichamps on November 01, 2011, 11:46:20 AM
Quote from: rayinreverse on November 01, 2011, 11:42:30 AM
Im going to recap my Butcher.
Would like to cut some of the highs. its a little too bright for me.
or maybe jsut do this to it.
http://www.davidsonamp.com/woodland_gallery/gallery_butcher.php
http://music-electronics-forum.com/attachments/11449d1288300024-peavey-butcher.pdf
Remove C6, C3, C15, C16, Try doing this one at a time, seeing what you like
assumption is you are using the high gain input
yes using high gain input. I was thinking of changing values of those caps, but you think just remove all together?
The function of C6, C15, and C16 are for treble peaking, they bypass resistive dividers to increase treble response, increasing them will let in more signal but will not cut high end. You could increase C3 to something say 10uF to 25uF but this will also increase gain at lower frequencies
Just change one of them, test, then move on if its not enough
Quote from: Hemisaurus on November 01, 2011, 11:48:05 AM
What's wrong with changing the coupling cap values? Most modern guitar amps have them about a tenth of what they should be? I'd hit that after the bright caps, and before cathode bypass :) I was eyeing up C2,3,6,8,9 for replacement, but that was more than my four, but the bright caps are the simpler call.
I hate having to repeat myself ;)
Quote from: Hemisaurus on November 01, 2011, 11:53:23 AM
Quote from: Hemisaurus on November 01, 2011, 11:48:05 AM
What's wrong with changing the coupling cap values? Most modern guitar amps have them about a tenth of what they should be? I'd hit that after the bright caps, and before cathode bypass :) I was eyeing up C2,3,6,8,9 for replacement, but that was more than my four, but the bright caps are the simpler call.
I hate having to repeat myself ;)
I missed it, sorry man. If people are looking for a thicker sound, bumping up those couplers will work.
Yeah, but your right, cutting out treble bleed first is easier and takes our the ice-pick.
Quote from: Hemisaurus on November 01, 2011, 11:55:26 AM
Yeah, but your right, cutting out treble bleed first is easier and takes our the ice-pick.
In my own shit I use a 220-330 pF bright cap on the gain pots but nothing else in the amp. I also use some plate snub caps to bring down the noise floor as well
this thread shall be the Hemi vs Nick thread hahahaha
Naw, we're in agreement so far, if you stop to read the thread properly ;)
Cheap bastards, we used to call those bright switches, and give people a chance to turn them off ;D
Quote from: Hemisaurus on November 01, 2011, 12:14:05 PM
Naw, we're in agreement so far, if you stop to read the thread properly ;)
Cheap bastards, we used to call those bright switches, and give people a chance to turn them off ;D
I usually dont like much bypassing on the pots, just a touch to maintain a little clarity. Gone are the days of Fender bright switches!!
Not you, I meant the plethora of bright caps in current production amps.
I really liked the Music Man Deep switch, it actually bypassed the coupling cap, which working from memory is only safe because it was an op-amp output into the phase inverter ;)
befoer anyone opens up their amp, please learn how to do it safely. learn how to discharge caps, and buy a voltmeter.
Quote from: Hemisaurus on November 01, 2011, 12:18:26 PM
Not you, I meant the plethora of bright caps in current production amps.
I really liked the Music Man Deep switch, it actually bypassed the coupling cap, which working from memory is only safe because it was an op-amp output into the phase inverter ;)
you could have a deep switch even on a normal gain stage, have a small coupling cap (10nF or whatever) in parallel with a a 47nF cap which is inseries with a 1meg resistor. Just use a switch to shunt the resistor and you can get a Deep mode
.022 is a pretty common coupling cap value, I'd cheerfully up that to .1 or even .22 ;D
of course my brain is generally working like this
(http://www.toomanyhelicopters.com/schems/Marshall_JMP_Preamps.gif) (http://www.toomanyhelicopters.com/schems/Marshall_JMP_Preamps.gif)
just watch out for blocking/grid current
aw heck paw, can'r we just use 10uF all round ;D
Quote from: Hemisaurus on November 01, 2011, 03:31:04 PM
aw heck paw, can'r we just use 10uF all round ;D
use large grid stoppers, >100k
Ok I am completely retarded when it comes to this stuff so can anyone get a pic of which caps to clip to make my vtm 60 less ice picky or explain to me how to find them? Also do these caps need discharged before clipping or is that just the filter caps on the power board?
No those particular caps won't have much of a charge, nor will your filter caps if your amp isn't broken. The cap leads are the red dots on this layout diagram.
(http://dub.greboguru.org/plt.jpg)
Unplug your amp, turn it on, let is sit for a minute.
"Unplug your amp, turn it on, let is sit for a minute."
I guess Im paranoid. I like to actually discharge the caps to be sure.
you can always measure with a meter and make a discharge stick. Given this particular problem with working on amp i always use some damn bleeders and I wish every amp company did 2
Quote from: Chovie D on November 01, 2011, 07:18:26 PM
"Unplug your amp, turn it on, let is sit for a minute."
I guess Im paranoid. I like to actually discharge the caps to be sure.
If the amp is working, turn it on without it plugged in does the same thing. If you're working around the HV you can always make sure with a meter, if you are snipping a cap from the top-side, I wouldn't worry.
But I guess he did say he was completely retarded, in which case my advice is
Take it to a tech!
I would take it to a tech but I am broke and if it is just clipping the caps I am comfortable doing that. Just needed help knowing which caps for sure because I would really not want to clip the wrong thing and have my amp get all shitty sounding.
Well clip the wrong caps, it may not sound atall. Maybe if Justin does it he'll take pics, I don't have one here to take pics of, we're working from schematics. You may find the board itself is labelled. It's the board the 12AX7's sit on. I suppose if you take pics of it, good pics, we can highlight the parts we're talking about.
Hopefully it is labelled and all you need to do is find the ones labelled C4 and C9 using the diagram as a road map. :)
so, I got these dip switches on my vtm120. and their a pain in the ass you need a paper clip to move them. and some are starting to break. I would like to just drill and add a bunch of switches(metal flip switches). would I even be able to do this?
They are all SPST switches (one switch element one pole, they ever connect or don't) if you can physically find the panel space for them I don't see why not. 5 of them are for grounding parts of the circuitry, and another couple are hooked together, so you have 8 in but only 3 out, which might make wiring them a little easier, you'll have eight connections in, and 3 out.
Finding the panel space may be tricky, as the board that all the other controls are mounted on will get in the way.
It's easy enough to figure out what switches what, you have two rows of eight pins, the switch connects pin 1 of row 1 with pin 1 of row 2, and so it goes on all the way along.
If you only ever tweak some of the switches you could always just run a hardwire where the ones you leave on are, and no connection between the ones you always leave off, and just add switches for the ones you actually use.
Ok I clipped those caps. Sounds much better. Kind of a half Marshall/half Orange tone. And now that I have done it can you explain to me what the caps were I got rid of and what it was they did to make it so trebley?
Quote from: BrianDamage on November 02, 2011, 09:54:58 PM
Ok I clipped those caps. Sounds much better. Kind of a half Marshall/half Orange tone. And now that I have done it can you explain to me what the caps were I got rid of and what it was they did to make it so trebley?
There are resistive dividers which are used to knock the amplitude of your signal down before each gain stage. If there is just a resistive divider is affects all frequencies equally. If you add a bypass cap effectively what happens is that frequency's above a certain cutoff will pass through the resistive divider without being attenuated where as frequencies below the cutoff are normally attenuated. Thus you get a much brighter tone
The caps bleed treble through :)
Quote from: Hemisaurus on November 02, 2011, 11:21:50 PM
The caps bleed treble through :)
sorry about my complicated explanation
Quote from: BrianDamage on November 02, 2011, 09:54:58 PM
Ok I clipped those caps. Sounds much better. Kind of a half Marshall/half Orange tone. And now that I have done it can you explain to me what the caps were I got rid of and what it was they did to make it so trebley?
brian, did you clip both of them? i should do that to my VTM . . .
Y'ALL FIND OUT HOW TO CLIP THIS CAP OFF MY 800'S BOARD WITHOUT ME HAVING TO TAKE THE ENTIRE FUCKING THING OUT!
Bright cap, kill it with fire~
I was too simplistic, I should have addd the word deliberately.
Sunn that is a freak of a Marshall, I'm having nothing to do with it ;)
You talking about C5 on that schematic? I don't know where they'd put it on yours, you can surely get at the component side of the PCB, no?
If it's really just clipping C5, I should just pop all the knobs and jacks, and just do it. Anything else interesting I should do to it?
Why not just clip one side of it close to the board first, if you like the sound, then dismantle it, if you don't, dismantle it, and solder the cap, back in.
Then again, why do I bother you always do the over complicated thing.
There isn't enough lead on that son of a bitch to clip. It's ceramic, if it were that easy, I would've done it. What's the value on it? I don't have the schem or layout handy at the moment... I should dig up a replacement before I snip anything out of it.
err, skip back a page :)
Quote from: justinhedrick on November 02, 2011, 11:28:28 PM
Quote from: BrianDamage on November 02, 2011, 09:54:58 PM
Ok I clipped those caps. Sounds much better. Kind of a half Marshall/half Orange tone. And now that I have done it can you explain to me what the caps were I got rid of and what it was they did to make it so trebley?
brian, did you clip both of them? i should do that to my VTM . . .
Yes I clipped them both. A much warmer amp now.
gratz sounds good. Sometimes thats all it takes
I can't believe it was that easy, all anybody wants is the bright caps gone?
Maybe we need photo essays on how to find the bright caps on popular models.
Do a cap change for my Model T including links to all proper caps!
Sent from my DROIDX using Tapatalk
Quote from: SunnO))) on November 03, 2011, 08:55:58 AM
Do a cap change for my Model T including links to all proper caps!
Sent from my DROIDX using Tapatalk
on the originals, according to the schematic there is only one bright cap for the Bright channel. However if you just jack into the Normal channel, there are no bright caps
To further decrease treble you would have to add some shunt caps in.
I think he's being funny. He needed to do a re-cap job. 'tis not in the spirit of the challenge dude, seeing as you already know all the values and where they go :P
Quote from: Hemisaurus on November 03, 2011, 09:10:05 AM
I think he's being funny. He needed to do a re-cap job. 'tis not in the spirit of the challenge dude, seeing as you already know all the values and where they go :P
Thats going to be a PITA, those 600V rated caps in that bitch are not exactly easy to come by
Quote from: BrianDamage on November 03, 2011, 12:44:44 AM
Quote from: justinhedrick on November 02, 2011, 11:28:28 PM
Quote from: BrianDamage on November 02, 2011, 09:54:58 PM
Ok I clipped those caps. Sounds much better. Kind of a half Marshall/half Orange tone. And now that I have done it can you explain to me what the caps were I got rid of and what it was they did to make it so trebley?
brian, did you clip both of them? i should do that to my VTM . . .
Yes I clipped them both. A much warmer amp now.
now, sorry for being so dense, but you did NOT clip the bright cap on the volume knob, right?
Sourcing the caps is going to be difficult? Balls.
Sent from my DROIDX using Tapatalk
Quote from: SunnO))) on November 03, 2011, 09:32:39 AM
Sourcing the caps is going to be difficult? Balls.
Sent from my DROIDX using Tapatalk
yea 600V caps are harder to find as most available ones are 450-500V which is below the working voltage in that amp. However, you could try stacked caps but this is going to alter the original schematic and the layout to accommodate 2 caps per node now. Stacked caps could easily get you 600+ Volt rated but you need to buy caps with 2 times the capacitance to get the right value. Node B and C are 450V rated 60-80uF caps, I can get you a decent deal through CE on those. However, the 2 initial caps are 20uF 600V so those are not as easy to find
http://sunn.ampage.org/site/schematics/modelt.gif
if you stack 2 40uF say 300-450V rated caps you would get 20uF effective with a rating of 600 to 900V. You will also need 220k 2W resistors to balance the voltage drops
EDIT
Well my bad you can get 20uF 600V caps from Sprague but boy they are fuckin expensive. Sprague has 20uF 600V caps for 15.40 a piece on CEDist. Big fuckers 2, 1.00" diameter x 3.90" length.
Also found them here, http://thetubestore.com/ca-at-20uf-600v.html. for cheaper 13.75.
Weber also has some 20uF 600V caps for those on a budget 2.00 a piece. I never used them b4 so I cannot comment on how good they are.
http://taweber.powweb.com/store/600Vcaps.jpg
I've got the regular Weber's (450 not 600) and they're fine. I did wonder about your comment, they're less common, but not unheard of. I'm trying to remember what we used in the 468's, they had cap cans, and some hideous cap values.
Quote from: Hemisaurus on November 03, 2011, 11:04:52 AM
I've got the regular Weber's (450 not 600) and they're fine. I did wonder about your comment, they're less common, but not unheard of. I'm trying to remember what we used in the 468's, they had cap cans, and some hideous cap values.
I have used weber 450/500V caps in amps b4, no problemo. In my own stuff I just use stacked caps rather than find a giant 600+V cap. Easier to do.
Precisely what Ernie Ball did in the HD-130 for the 725V plate voltage, stacked two 450V 100uF ;D
725 plate, thats nuts. Was it running 34s or 88s?
Quote from: justinhedrick on November 03, 2011, 09:22:36 AM
Quote from: BrianDamage on November 03, 2011, 12:44:44 AM
Quote from: justinhedrick on November 02, 2011, 11:28:28 PM
Quote from: BrianDamage on November 02, 2011, 09:54:58 PM
Ok I clipped those caps. Sounds much better. Kind of a half Marshall/half Orange tone. And now that I have done it can you explain to me what the caps were I got rid of and what it was they did to make it so trebley?
brian, did you clip both of them? i should do that to my VTM . . .
Yes I clipped them both. A much warmer amp now.
now, sorry for being so dense, but you did NOT clip the bright cap on the volume knob, right?
No just the ones on the preamp board. Although I have read a lot of people clip the bright cap (c2) on the control board by the pre gain knob.
Clipping the gain pot bright caps is good if your running the amp on lower gain settings but once the gain is nearly full, the bypass cap isnt doing much as nearly all of the signal is coming through already
Quote from: dunwichamps on November 03, 2011, 01:28:53 PM
Clipping the gain pot bright caps is good if your running the amp on lower gain settings but once the gain is nearly full, the bypass cap isnt doing much as nearly all of the signal is coming through already
brian, how are you running yours?
nick, i'd be running mine clean, so would it be more adventagious (sp?) to clip the ones on the pre-amp board, or the one by the volume control?
you can clip either one then, The ones on the preamp board are on fixed resistive dividers unlike the pot caps which are more and more effective as you turn the signal down
I run my preamp pretty clean and turn up the post until the power amp starts to break up. I get most of my dirt from pedals.
Quote from: dunwichamps on November 03, 2011, 11:29:52 AM
725 plate, thats nuts. Was it running 34s or 88s?
Quad of 34's with a 5.5K primary, we did this discussion before, remember, step it up to 800V and you can get 200W out of it.
I submit this conundrum on behalf of my drummer, who's a guitarist. He recently got himself a circa 1986 Hiwatt Lead 100, yeah we already know it's not a real Hiwatt. Anyway, although the clean channel sounds good on it's own, it sounds weak and fizzy with his Big Muff or Hot Cake running into it. He says it sounds a little better on the lead/overdrive channel with its OD knob turned down, but still not that great. He runs a stereo rig with a 70's Jansen Bass 50 on the other side and it's putting his Hiwatt to shame when he kicks in the distortion. Any ideas about changes or mods that can be done? Please and thank you.
How does the Jansen sound clean? My first thought would be blame the Muff, not the amp. My second thought is what's the real model # is it a DR an L100 or what, I don't recall one with two channels, HiWatts were always pretty bog simple.
You could degain the first stage, either by changing the plate resistors, or just putting in say a 12AU7, if that was where it's breaking up, but that would affect the clean sound too. I'm still baffled by this channel business, a two channel HiWatt, really?
(http://hiwatt.org/Schematics/DR_LEAD_2InputPre.gif)
I thought we were dealing with this guy. Is he saying it sounds better into the Brilliant input?
If you want to turn it back to a more traditional HiWatt sound, you just lose the extra tube stage. Disconnect the 220K resistor running to pin 6 of V2, connect the wire running to pin 7 to pin 2 instead, and remove that pot connection to pin 2. You've now disconnected the extra tube stage.
EDIT: If you just want to try it, you don't need to disconnect the 220K resistor, just disconnect the pot from pin 2 and move the connection from pin 7 to pin 2, disconnecting the 220K just removes the power from the extra tube stage, you can leave it running for a test.
i would convert V2 into a DC coupled follower but thats hiwatt blasphemy.
4 moves or less, can you do it? ;D
i also like the bootstrapped DC followers 2. I like the tone stacks driven via a CF, but their TS is unique, closer to an FMV but more complicated.
Quote from: dunwichamps on November 08, 2011, 09:30:53 AM
Quote from: Hemisaurus on November 08, 2011, 09:30:11 AM
Quote from: Hemisaurus on November 08, 2011, 09:20:09 AM
4 moves or less, can you do it? ;D
sure sure but not my amp to butcher up
OK, we'll believe you.
Remember the Mantra anyway, simple first. As there's no bright caps, and it sounds best with the OD all the way down, lets skip the extra gain stage DR added for that 80's sound.
Quote from: Hemisaurus on November 08, 2011, 09:45:15 AM
Quote from: dunwichamps on November 08, 2011, 09:30:53 AM
Quote from: Hemisaurus on November 08, 2011, 09:30:11 AM
Quote from: Hemisaurus on November 08, 2011, 09:20:09 AM
4 moves or less, can you do it? ;D
sure sure but not my amp to butcher up
OK, we'll believe you.
Remember the Mantra anyway, simple first. As there's no bright caps, and it sounds best with the OD all the way down, lets skip the extra gain stage DR added for that 80's sound.
You could do that, preferably dont let V2b go to waste run a // stage, better S/N and would sound nice.
Quote from: Hemisaurus on November 08, 2011, 09:45:15 AM
Remember the Mantra anyway, simple first.
Original Hi-Watts left half of V2 unused.
(http://hiwatt.org/Schematics/DR_PreLinkedInput_v1.gif)
Let's try and keep it Hi-Watt ;D
conformist! we gotta stick it to the man
j/k
this is a serious mod, be careful if either you or the drummer attempt it
Which mod, mine or yours? Mine is pretty easy ;)
I'm just confused, you snip a couple of caps on a Peavey and call it done, but give you a Hi-Watt and you want to butcher it, shome mishtake shurely? Those things are so pretty.
(http://hiwatt.org/images/DR105guts2sm.jpg)
its not a 70s model or even an early 80s. Plus he is asking something different than just, its too bright.
Its serious because it involves high DC potential lines, and risk of shock where as snipping a bright cap on a resistive divider is okay, assuming you dont go trolling around with your snips
Just cuz she's pretty dont mean u cant cut her
She's an L100 from '86. I had the s/n when drummer was looking at it to verify it's (un)desirability, to which I ended up telling him "If it sounds good, it sounds good. But it'll only be a Hiwatt in name alone". It's not Hylight or even Biacrown, nor is it a Sterling. I cant' actually remember who built this one, I think it started with a 'T'. It's all pcb mount this and that, based on internet photos. Haven't opened it up yet. I could see it's got 12ax7a preamap valves in 'er and I think it's EL34s in the power amp.
Apparently to model was kinda meant to compete against the JCM900 and has diode clipping on the lead/od channel. Both channels have their own tone controls which leads me to believe it's not just an extra gain stage.
Also, the Jansen he uses run pretty clean, comparable to how he runs the Hiwatt, as he's running a big ol' pedalboard and only wants it to get dirty when he tells it to. He uses a Crowther Double Hot Cake which sounds fizzy on the Hiwatt, too.
Ooh, I don't know that one, that is the schematic for the earlier L100 (I haven't seen a later one) where it just had a brilliant and a regular input and then everything else is the same.
If it's to go up against the JCM900 does it have the god-awful active tone stack???
I'll see if I can find a schematic, but in lieu of that we'd have to have it on the bench in front of us.
Got schematic, need to find one with component values. I swear there was a 4 page PDF somewhere.
(http://drtube.com/schematics/hiwatt/hwpre4.gif)
It should oughta be something like the picture you got there, I think, but without the reverb. When I was searching around online last night I saw a comment about the schematic without the component values having inaccuracies, though I didn't see any schematics myself.
Well in lieu of a dcent schematic, I'd resort to tube swapping, get a 12AU7 or possibly better a 12DW7, or really any 12XX7 tube type, all are lower gain than the AX, the reason I said DW it's half an AU and half an AX in the same tube, so it only gains down one stage. Try swapping out V1 which should be the clran channel, you can also try it in V2.
If either sounds improved, we're moving in the right direction.
We'll give that a crack, I reckon. If it were mine, it'd be here for me to open and try and trace it out. Trying to save the guy from resorting to fork over an undisclosed sum to a local tech who may, or may not improve things. The tragedy is, when he bought the amp there was a twin brother of his Jansen for sale at a cheaper price, though it would've required servicing.
Another VTM question...
Since I don't use hardly any preamp gain the "bright cap" is working in my amp. Since I already clipped the other two caps to make it less bright what effect would taking out the bright cap have on the tone? Would it make it ridiculously dark or just awesomely dark?
Quote from: BrianDamage on November 13, 2011, 07:52:32 PM
Another VTM question...
Since I don't use hardly any preamp gain the "bright cap" is working in my amp. Since I already clipped the other two caps to make it less bright what effect would taking out the bright cap have on the tone? Would it make it ridiculously dark or just awesomely dark?
Thats all a matter of taste u can clip off the cap but leave enough leads to add in another cap maybe something smaller, say 100pF for just a touc of high end
Quote from: Hemisaurus on November 09, 2011, 12:02:29 AM
Well in lieu of a dcent schematic, I'd resort to tube swapping, get a 12AU7 or possibly better a 12DW7, or really any 12XX7 tube type, all are lower gain than the AX, the reason I said DW it's half an AU and half an AX in the same tube, so it only gains down one stage. Try swapping out V1 which should be the clran channel, you can also try it in V2.
If either sounds improved, we're moving in the right direction.
I swapped out the 12AX7-A on V1 for a 12AU7 tonight. It has indeed made an improvement. I'll see how my drummer gets on with it after his 'other band' has their next practice.