Guitar Gear Forum

snapitup12 wrote:What are good tubes for all around sound from classic rock to metal?

Real happy with my JJs, but don't have any point of comparison other than the stock (crappy) chinese tubes.

I keep hearing great things about the 6L6wxt's

Best advice I have is contact Eurotubes, Valve Queen, or one (or more) of the other tube sources. They'll bend over backwards to steer you right and have killer service.

Tonight, I (re-)fell in love with my JCA50. I the clean switch and scoop mods last year, per Edge11's mods, but never really did much with them. Now that I've had a chance to spend time with an old Fender amp, I have a little better understanding of what I'm looking for. And now, I realize that there is really something to the 'Fenderish' tones he described on those mods. Killer lo-gain stuff. Gonna rock my new pedalboard on it tomorrow night to make sure, but I think I'm gonna be real happy!

So I'm finding myself lately wanting more clean range from the clean channel gain knob on my JCA100. As it stands right now, it gets into overdrive when the gain is at about 3, and just gets more and more crunchy after that. I'd like it to start breaking up at about 5 and gradually easing into a mid-gain crunch by about 7. I'm wondering how to go about getting that kinda responsiveness.

Lower gain V1 tube? (I currently have a Tung Sol 12ax7)

or Clean switch mod?

Obviously, sticking in a new tube will be a lot easier, but the downside is that if I put in a 5751 or a 12at7 or 12ay7, the tone of the amp overall could change as well.

What's the skinny on the clean switch (grimespace, I'm lookin your way)? Pros/Cons?

Clean switch is good, and I added another switch (per Edge's prompting) for the scoop mod as well. Both affect the first channel only. Biggest shock to me after doing so was the tremendous loss of volume when I engaged the switch - I was originally thinking I might try to do some kind of footswitch-controlled relay that would essentially make it a 3-channel amp, but there's no way to deal with the volume difference between clean/crunch without more mods. Basically, you have to push the gain control up quite a bit higher than what I (and you, from what I'm reading) would normally want for the crunch. I pretty much didn't use the switch much after putting it in, but like I said in the post above, I tried it out the other night, and was pretty floored with the Fender-like tones I was getting. The thing is, I already have a pretty cool Fender amp (see sig), so it's not that necessary for me. I do recommend that you try it, as long as you're comfortable busting the amp open (and following all the precautions so we don't have to have to start handing out Darwin awards). And, if you're diving in, make sure you do the depth knob.

All that being said, I completely agree with you about the overall gain of the amp. Even with the super-hot pickups in my SG, I wouldn't ever push gain above 4-5 on the OD channel, which I normally keep at just a hair under 3. With my Carvin (slightly less hot pickups), I run about 3-1/2. OD channel I keep around 4 or so for a pretty good AC/DC flavor.

I've heard a bit about 5751 in V1 being a good idea. I really want to try that in the near future. I did try out an at7, and wasn't thrilled at all.

So whats the deal with the effect loop? Does all digital stuff work with it ?

Was looking at the GSP1101, Nova System and G Major2. Also maybe some T-Rex pedals but I think they can do +4 so I they should work ?

My arsenal:

JCA100HDM with Saturation mod
JCA100H
JCA22H
JCA24S
JCA24S+ (awesome!)
Whitebox Engineering 2x12 with WGS ET65S

Small club gigs with stage volume only get the JCA22H + Whitebox 2x12.
Small club gigs with PA get the 24S+ to the board.

Oh, and my Afterburner OD should be here any day now...

snapitup12 wrote:So whats the deal with the effect loop? Does all digital stuff work with it ?

Was looking at the GSP1101, Nova System and G Major2. Also maybe some T-Rex pedals but I think they can do +4 so I they should work ?

Not sure about those devices - did you check the list in post #2? Perhaps Billy will see this and respond - he's been the expert on this stuff. If you do try them, make sure to let us know if they work or not.

Guess The Flood is coming too...

GRIMESPACE wrote:Clean switch is good, and I added another switch (per Edge's prompting) for the scoop mod as well. Both affect the first channel only. Biggest shock to me after doing so was the tremendous loss of volume when I engaged the switch - I was originally thinking I might try to do some kind of footswitch-controlled relay that would essentially make it a 3-channel amp, but there's no way to deal with the volume difference between clean/crunch without more mods. Basically, you have to push the gain control up quite a bit higher than what I (and you, from what I'm reading) would normally want for the crunch. I pretty much didn't use the switch much after putting it in, but like I said in the post above, I tried it out the other night, and was pretty floored with the Fender-like tones I was getting. The thing is, I already have a pretty cool Fender amp (see sig), so it's not that necessary for me. I do recommend that you try it, as long as you're comfortable busting the amp open (and following all the precautions so we don't have to have to start handing out Darwin awards). And, if you're diving in, make sure you do the depth knob.

All that being said, I completely agree with you about the overall gain of the amp. Even with the super-hot pickups in my SG, I wouldn't ever push gain above 4-5 on the OD channel, which I normally keep at just a hair under 3. With my Carvin (slightly less hot pickups), I run about 3-1/2. OD channel I keep around 4 or so for a pretty good AC/DC flavor.

I've heard a bit about 5751 in V1 being a good idea. I really want to try that in the near future. I did try out an at7, and wasn't thrilled at all.

Hmm. that's a bunch of food for thought.

What I do right now for clean cleans is drop the normal channel gain to about 2, and use the channel volume to match it up to the OD channel volume. At home I play with the OD volume on about 1, but with a band, it's usally at about 4 or 4.5. In both cases, the clean channel volume needs to be higher than the OD volume for it to sound about equal, given the low gain of the clean channel.

I like to have the clean channel actually be clean, because I generally use pedals for varying levels of crunch. I boost the clean channel for a light breakup. Fulltone OCD for warm overdrive. Boost + OCD for solid mid-high gain crunch. And OD channel for high gain (with option for boost and/or OCD for extra balls)

I'm wondering if there's even any point. Maybe I'll try a 5751, and if that's not too great, then I think I'll just leave it as is. I couldn't really be arsed to get into a major mod if I may or may not like it, and especially if I don't really need it.

Also, I've already done the depth mod some time ago. I do have another mod which I'll start in a few days (or whenever the parts arrive) - changing out the pilot light to a normal fender-esque bulb assembly with either an Amber or Purple jewel (can't decide yet). I've been meaning to put a 68k slope resistor on a switch though, so I think I'll do that. Edge 11 said it'd make the amp more Marshally.

CTN wrote:Hmm. that's a bunch of food for thought.

What I do right now for clean cleans is drop the normal channel gain to about 2, and use the channel volume to match it up to the OD channel volume. At home I play with the OD volume on about 1, but with a band, it's usally at about 4 or 4.5. In both cases, the clean channel volume needs to be higher than the OD volume for it to sound about equal, given the low gain of the clean channel.

I like to have the clean channel actually be clean, because I generally use pedals for varying levels of crunch. I boost the clean channel for a light breakup. Fulltone OCD for warm overdrive. Boost + OCD for solid mid-high gain crunch. And OD channel for high gain (with option for boost and/or OCD for extra balls)

I'm wondering if there's even any point. Maybe I'll try a 5751, and if that's not too great, then I think I'll just leave it as is. I couldn't really be arsed to get into a major mod if I may or may not like it, and especially if I don't really need it.

Also, I've already done the depth mod some time ago. I do have another mod which I'll start in a few days (or whenever the parts arrive) - changing out the pilot light to a normal fender-esque bulb assembly with either an Amber or Purple jewel (can't decide yet). I've been meaning to put a 68k slope resistor on a switch though, so I think I'll do that. Edge 11 said it'd make the amp more Marshally.

Didn't realize you had the 100. When you're running OD volume at 4, what is your normal channel volume? I would imagine with gain of 2, it'd have to be pretty high. With that setup, do you still have some 'dirt' in the sound? I would think it'd be pretty clean, especially given the extra headroom (I've got a 50).

Unfortunately, I don't have a ton of experience yet running the amp at the volume you are, but I think I can relate to what you're trying to achieve. I think your best bet is to get a 5751 and see how it responds. My guess is that it'll take that last bit of 'hair' off the normal channel and keep some warmth when you're running clean, such that kicking in a bit of OD with pedals won't take it into sterile solid-state territory.

I had big hopes for my pedals with the clean switch after finding some settings that were very reminiscent of my Fender, but wound up disappointed. The Fender really seems to stay warm with my Bad Monkey (basic OD) and Ultimate Drive (OCD-like), but the JCA with clean switch was sterile and cold sounding. It may be that the lower volume I'm running my JCA setup at is part of the problem - it's at home, and the Fender is at my rehearsal space where it's running at a bit higher volume with more open space. Writing this, I'm suddenly thinking I should take the JCA out sometime soon and give it a shot...

How do you like the depth mod? I've heard it's more prominent at lower volumes, and that it's not really necessary when you open the amp up in a band situation.

What overall tonality are you going for with your band? Can you describe the rest of your setup (speakers, pickups, etc.)? It sounds like you're after a similar lower-gain territory that I'm after. I bought the amp to get some good rock/hard rock/ early metal tones without breaking the bank. I've been very happy with it so far, especially with the tube change and depth mod, but it's mainly been at lower volumes.

I'll have to go back and check for that slope resistor mod. 'Marshally' sounds like a good thing to me. And, if you do beat me to trying out that 5751, I'm very anxious to hear about it.

GRIMESPACE wrote:Didn't realize you had the 100. When you're running OD volume at 4, what is your normal channel volume? I would imagine with gain of 2, it'd have to be pretty high. With that setup, do you still have some 'dirt' in the sound? I would think it'd be pretty clean, especially given the extra headroom (I've got a 50).

With the OD up at about 4, the clean volume ends up being at about 6 - 6.5. Fortunately, because it's 100W, there's a good bit of headroom so it stays mostly clean, but of course, picking hard will overdrive it a bit. Put the Clean channel gain lower than 2 and goose the volume and it gets almost chimey sounding.

Unfortunately, I don't have a ton of experience yet running the amp at the volume you are, but I think I can relate to what you're trying to achieve. I think your best bet is to get a 5751 and see how it responds. My guess is that it'll take that last bit of 'hair' off the normal channel and keep some warmth when you're running clean, such that kicking in a bit of OD with pedals won't take it into sterile solid-state territory.

I had big hopes for my pedals with the clean switch after finding some settings that were very reminiscent of my Fender, but wound up disappointed. The Fender really seems to stay warm with my Bad Monkey (basic OD) and Ultimate Drive (OCD-like), but the JCA with clean switch was sterile and cold sounding. It may be that the lower volume I'm running my JCA setup at is part of the problem - it's at home, and the Fender is at my rehearsal space where it's running at a bit higher volume with more open space. Writing this, I'm suddenly thinking I should take the JCA out sometime soon and give it a shot...

Yeah i mean the clean switch sounds like a great idea in theory, but if it's gonna kill off a lot of the soul and character of the amp, then that's a no-go for me.

How do you like the depth mod? I've heard it's more prominent at lower volumes, and that it's not really necessary when you open the amp up in a band situation.

What overall tonality are you going for with your band? Can you describe the rest of your setup (speakers, pickups, etc.)? It sounds like you're after a similar lower-gain territory that I'm after. I bought the amp to get some good rock/hard rock/ early metal tones without breaking the bank. I've been very happy with it so far, especially with the tube change and depth mod, but it's mainly been at lower volumes.

Love the depth mod. gives me SO much more control over the character of the low end. Unfortunately, I haven't had a chance to jam nice and loud since doing the depth mod, so I can't comment on how it does at high volume. Tonality of the band I was using it in was thrash/black/death metal. Tones were modern high gain stuff with lots of mids.

for example:
https://soundcloud.com/will-of-the-ancients/will-of

I'll have to go back and check for that slope resistor mod. 'Marshally' sounds like a good thing to me. And, if you do beat me to trying out that 5751, I'm very anxious to hear about it.

Will definitely let you know about it when I get them in. I'm also planning to experiment with a 12au7 in the PI/V5 position, as I've heard that it works wonders in the 20H. I'll probably get the tubes in a week or two, but the pilot light and slope resistor I can probably get done soon as the pilot light arrives (ie sometime this week).

Cheers!

@CTN: Good stuff - I guess you're using the OD a lot more than I thought - cool high-gain stuff. Really like the band on the clip (no offense, but the vox aren't my thing). Very interested to hear back on depth mod in louder environment, and especially can't wait to hear about the 5751 and the PI you mentioned, as well as the slope resistor. When I was modding my 50H, I started doing a bunch of Edge11's changes (cathode bypass, etc.), but just didn't work out for me. I think the amp (with better tubes and depth mod) really stand on its own and don't need a massive amount of changes. I mean, it is a Soldano at heart, and it does cover a lot of ground that I'm looking for. Any more, and I'd probably rather be looking at other platforms.

@justinjag77: very nice - I remember your postings from HCAF and the short-lived JCA forum. Did you ever figure out how to light up the LED strips using internal power, or are you still using a wall wart?

glad you dug the clip. that's the opening song of the album I recorded with that band. I used my JCA100 and a Splawn QuickRod for my rhythm tracks, other guitarist used a 6505 and Laney VH100R.

I totally hear ya about the amps being great with a minimal amount of mods. A lot of the mods that Edge11 posted, I just don't really see the point of them, cuz the amp's versatile enough on its own.

Also, I managed to nab some NOS tubes for good prices from a guy in Quebec. 5751 and 12au7, both JAN General Electric.

That's quite a testimony for JCA, being held in fair regard against a herd of other amps like that. Any chance of a clip of the same recording of just the JCA track solo'd (all other tracks removed)? Just a taste would be great to see how much of that is JCA.

How much are you paying for those tubes? Is it a one-time source, or does he have more to sell?

I'd also be interested in the settings you used

GRIMESPACE wrote:That's quite a testimony for JCA, being held in fair regard against a herd of other amps like that. Any chance of a clip of the same recording of just the JCA track solo'd (all other tracks removed)? Just a taste would be great to see how much of that is JCA.

haha, stands up just fine. As billy used to say, the JCA100 is about 99% the tone of the Hot Rod 100, and I'm sure that'd also sound just fine alongside those amps. I'd say at least a 1/4 of that overall sound is the JCA. We tried to dial in the same basic sound each time, and let the naturally different characters of the different amps fill in each others' holes, so to speak. I'll have to talk to the guy mixing it to see if I can get a clip.

How much are you paying for those tubes? Is it a one-time source, or does he have more to sell?

$19 and $17.
http://www.dbtubes.com
http://www.dbtubes.com/tube-detail.php?ID=2168 (5751 - not many left of these)
http://www.dbtubes.com/tube-detail.php?ID=2327 (12au7 - he's also got a whooooooole bunch of other 12au7s at other prices, just use the search function)

Grimespace:

just FYI, I goofed on the slope resistor value for the marshally mod.

This is what I asked Edge11:

Lately I've been trying to tweak the tone controls/depth/presence controls while playing on the overdrive channel, trying to get that bright/middy hot rodded JCM800 kinda sound, but I always find that the overdrive channel has far too much low/low-mid muscle to do the Marshall sound.

Is there a mod for a voicing switch or something similar that would be able to give the OD Channel a more Marshall flavour?

And he replied:

Change the slope resistor to 33k. r24 on the 50h Idk what # it is on the 100h. the original value is 47k change it to 33k.

Turns out it's R24 on the 100H too.


Edit: Changed out the pilot light for a nice sturdy Fender style assembly with a bulb and an amber jewel to match the tan grill cloth on the baffle and on my cab. Also finally got a full set of matching high quality cream chickenhead knobs. Not gonna post pics until I get the 12au7 and 5751 in and have a chance to experiment, as well as do the marshally slope resistor mod.

Guys, when your doing the depth mod to a jca22h, do I need any particular wire?
I want to run it to the front and have the pot there. Does it need a certain amp or voltage rating?

CTN wrote:Grimespace:

just FYI, I goofed on the slope resistor value for the marshally mod.

This is what I asked Edge11:

Lately I've been trying to tweak the tone controls/depth/presence controls while playing on the overdrive channel, trying to get that bright/middy hot rodded JCM800 kinda sound, but I always find that the overdrive channel has far too much low/low-mid muscle to do the Marshall sound.

Is there a mod for a voicing switch or something similar that would be able to give the OD Channel a more Marshall flavour?

And he replied:

Change the slope resistor to 33k. r24 on the 50h Idk what # it is on the 100h. the original value is 47k change it to 33k.

Turns out it's R24 on the 100H too.


Edit: Changed out the pilot light for a nice sturdy Fender style assembly with a bulb and an amber jewel to match the tan grill cloth on the baffle and on my cab. Also finally got a full set of matching high quality cream chickenhead knobs. Not gonna post pics until I get the 12au7 and 5751 in and have a chance to experiment, as well as do the marshally slope resistor mod.

I totally missed the connection from the first page until you mentioned the tan grill cloth. I do remember you (Blakkwater) from HCAF, too. Good to be here with you. I really do like what you did with your rig. Can you give more details - what grill cloth did you use? How about the cab - I don't know much about the Sunn - good match for the JCA with that speaker config?

I think the new light and chickenheads are going to make a ton of difference matching up to the look you've got there, and I can't wait to see new pics. It seems like chickenheads have shown up on enough of our modded heads that they oughta come stock that way. But then, again, I also think better tubes and the depth knob should also be stock, and all these things probably would end up driving the price higher, which I know they don't want to do.

If you think about it (and have the time), any clips you capture / post of the sound before and after changing the tubes be really helpful, along with your description. I'm actually very excited to hear back on the 5751 and 12auy7 and the difference on gain as well as tone. I'll definitely be all over this I can get more usable low-gain on both channels, and on-paper, the 5751 sounds like it should help - just not convinced it's going to be that big an impact.

**Edit - just looked (again) at your earlier post - I see you already had chickenheads, so were they white before and you're changing to cream colored? I really like the retro-look you're going for! I'd really like to redo the front of my speaker cabs with grillcloth like yours - I'lll probably will wait until I get a proper 4x12 and rebuild my 2x12, though.

Jase01 wrote:Guys, when your doing the depth mod to a jca22h, do I need any particular wire?
I want to run it to the front and have the pot there. Does it need a certain amp or voltage rating?

Hi Jase - did you get the volume 'rush' issue sorted out?

First of all, if you're doing anything with the chassis open, make sure you totally understand (and do) everything about discharging the filter caps. If you don't, you need to take the amp to a qualified tech to help you out.

Here's some info on the depth knob that I'm copying from my postings on the 50/100/22h mod thread over on HCAF:

Here's the basics along with some tips. It's only 2 components and some wire - a 1 meg audio taper pot and a .0047uf 400v orange drop cap. Hardest part was drilling the front panel (I wanted mine right next to the Presence knob, like the 100HDM) without dropping metal shavings into the chassis or running right through the filter caps, which are only about 5/8" from exactly where I placed the pot . I clamped a scrap piece of 5/8 wood on the inside where I was drilling so that my drill wouldn't punch through wildly, and was really careful about shavings. The pot basically gets inserted between the NFB (negative feedback) resistor and the 4 ohm output at the back panel. There's a red wire going to the pcb (pad label: FB) that I desoldered from the output jack and ran to the front panel where the new pot was being installed. A new wire was put in from the output jack to the other lug on the pot, and voila - done.

Also, I later added in a .1uf cap inline with the depth control, which had been recommended by Edge (he got it from someone else), that helps with scratchiness in the control as the knob is turned. I think it helps block DC from getting into the signal path before it reaches the pot (or something like that).

I've all been beating down everything I could to find info on the hookup wire - I wound up using 20ga PTFE wire. Not totally certain about the voltage rating.

GRIMESPACE wrote:
I totally missed the connection from the first page until you mentioned the tan grill cloth. I do remember you (Blakkwater) from HCAF, too. Good to be here with you. I really do like what you did with your rig. Can you give more details - what grill cloth did you use? How about the cab - I don't know much about the Sunn - good match for the JCA with that speaker config?

haha hiya!
The grill cloth is a cane/polyester ribbon cloth sold by McBride Loudspeaker in Waterloo, Ontario, Canadia.
http://qcomponents.ca/product.php?produ ... 101&page=3

Looks like this:


The cab is a great match! It's a straight cab, not really oversized or anything, but very solidly built, all birch ply, no MDF in sight. The speaker combination is fantastic. It's thick, rich, articulate and crispy, but can be warm and smoky sounding too. When I first got the cab it had 4 G12T-75s in it, and holy hell, i hated it. I love to hear ample mids in my tone and the 75s just couldn't hack it. I traded a guy two of the 75s for two G12-65's (I dunno wtf he was thinking. They're early 80s English ones too, and he just wanted to do a straight swap, despite his speakers easily being twice the value of the 75s I was giving him). That helped my tone a bit...added some much needed mids, but it still wasn't enough articulation for my tastes, so I ended up buying a couple of Retro 30s, and I've been happy as a pig in shit ever since.

I think the new light and chickenheads are going to make a ton of difference matching up to the look you've got there, and I can't wait to see new pics. It seems like chickenheads have shown up on enough of our modded heads that they oughta come stock that way. But then, again, I also think better tubes and the depth knob should also be stock, and all these things probably would end up driving the price higher, which I know they don't want to do.

Yeah it looks real nice And I agree about the tubes and depth knob, but seeing as Jet City is a lower priced brand, you're right it's not something they would want to do...besides, tubes can be a very personal thing. But the depth knob at least should be standard it's what, $5 in parts? Though that might render the 100HDM obsolete except for the fancy schmancy baffle and the half power switch.

If you think about it (and have the time), any clips you capture / post of the sound before and after changing the tubes be really helpful, along with your description. I'm actually very excited to hear back on the 5751 and 12auy7 and the difference on gain as well as tone. I'll definitely be all over this I can get more usable low-gain on both channels, and on-paper, the 5751 sounds like it should help - just not convinced it's going to be that big an impact.

Yep I'll record a bunch of clips and post them in here. I'll probably try the 5751 and the 12au7 in V1 and PI positions and swap em back and forth and see what difference (if any) there is, although the intention was 5751 for V1 and 12au7 for PI.

**Edit - just looked (again) at your earlier post - I see you already had chickenheads, so were they white before and you're changing to cream colored? I really like the retro-look you're going for! I'd really like to redo the front of my speaker cabs with grillcloth like yours - I'lll probably will wait until I get a proper 4x12 and rebuild my 2x12, though.

Well, not exactly... I had pedal style knobs on all the pots except for the channel volumes which had chickenheads. And the colours didn't match. While both were supposed to be cream, the chickenheads were lighter and very slightly translucent. Also, they were all of the set-screw variety so they were all slightly different in terms of being accurate in regards to where the indicator was pointing. The new knobs are push-on type, so they all point the same direction and indicate more accurately lol.

GRIMESPACE wrote:

Jase01 wrote:Guys, when your doing the depth mod to a jca22h, do I need any particular wire?
I want to run it to the front and have the pot there. Does it need a certain amp or voltage rating?

Hi Jase - did you get the volume 'rush' issue sorted out?

First of all, if you're doing anything with the chassis open, make sure you totally understand (and do) everything about discharging the filter caps. If you don't, you need to take the amp to a qualified tech to help you out.

Here's some info on the depth knob that I'm copying from my postings on the 50/100/22h mod thread over on HCAF:

Here's the basics along with some tips. It's only 2 components and some wire - a 1 meg audio taper pot and a .0047uf 400v orange drop cap. Hardest part was drilling the front panel (I wanted mine right next to the Presence knob, like the 100HDM) without dropping metal shavings into the chassis or running right through the filter caps, which are only about 5/8" from exactly where I placed the pot . I clamped a scrap piece of 5/8 wood on the inside where I was drilling so that my drill wouldn't punch through wildly, and was really careful about shavings. The pot basically gets inserted between the NFB (negative feedback) resistor and the 4 ohm output at the back panel. There's a red wire going to the pcb (pad label: FB) that I desoldered from the output jack and ran to the front panel where the new pot was being installed. A new wire was put in from the output jack to the other lug on the pot, and voila - done.

Also, I later added in a .1uf cap inline with the depth control, which had been recommended by Edge (he got it from someone else), that helps with scratchiness in the control as the knob is turned. I think it helps block DC from getting into the signal path before it reaches the pot (or something like that).

I've all been beating down everything I could to find info on the hookup wire - I wound up using 20ga PTFE wire. Not totally certain about the voltage rating.

Cheers for that. Been a bit stretched for time lately, but volume rush seems to be better for some unknown reason.
I've put JJ el84's in and have a selection of 12ax7's to try. Got some JJ's, a Electro Harmonix or two a Tung Sol and a Sovtek 12ax7lps
that I've managed to scrounge from various places to try as well.
Plus I got a biasing kit from Amphead and will hopefully be doing that today or over the weekend.
Do I need to take a plate voltage reading from both tubes? or just the one then set the bias to that?

Jase01 wrote:Cheers for that. Been a bit stretched for time lately, but volume rush seems to be better for some unknown reason.
I've put JJ el84's in and have a selection of 12ax7's to try. Got some JJ's, a Electro Harmonix or two a Tung Sol and a Sovtek 12ax7lps
that I've managed to scrounge from various places to try as well.
Plus I got a biasing kit from Amphead and will hopefully be doing that today or over the weekend.
Do I need to take a plate voltage reading from both tubes? or just the one then set the bias to that?

Make sure you let us know what tube you wind up using and where. FastRedPonyCar (on of our long-standing experts on all things JCA) stated the biggest impact would be V1, V2, PI, and of course, output tubes. He didn't seem to feel there was much benefit to changing from the stock tubes in V3 and V4, iirc.

Not sure how to handle the biasing question - I think I read that someone took readings on both and averaged them, which seems to make sense. Hopefully one of the more experienced here can chime in on that. I only did one tube, and either I got lucky, or its just not that much rocket science.

Last thing - if you don't promise to follow proper cap discharge protocol, I'm not gonna talk to ya anymore I really don't want to read about your next of kin attributing the (posthumous) Darwin award to the dipshit on GAB giving the advice on how to blow your ass up. Again, if you don't know what I'm talking about, don't even think about unscrewing the chassis from the headshell, 'k?

GRIMESPACE wrote:

Jase01 wrote:Cheers for that. Been a bit stretched for time lately, but volume rush seems to be better for some unknown reason.
I've put JJ el84's in and have a selection of 12ax7's to try. Got some JJ's, a Electro Harmonix or two a Tung Sol and a Sovtek 12ax7lps
that I've managed to scrounge from various places to try as well.
Plus I got a biasing kit from Amphead and will hopefully be doing that today or over the weekend.
Do I need to take a plate voltage reading from both tubes? or just the one then set the bias to that?

Make sure you let us know what tube you wind up using and where. FastRedPonyCar (on of our long-standing experts on all things JCA) stated the biggest impact would be V1, V2, PI, and of course, output tubes. He didn't seem to feel there was much benefit to changing from the stock tubes in V3 and V4, iirc.

Not sure how to handle the biasing question - I think I read that someone took readings on both and averaged them, which seems to make sense. Hopefully one of the more experienced here can chime in on that. I only did one tube, and either I got lucky, or its just not that much rocket science.

Last thing - if you don't promise to follow proper cap discharge protocol, I'm not gonna talk to ya anymore I really don't want to read about your next of kin attributing the (posthumous) Darwin award to the dipshit on GAB giving the advice on how to blow your ass up. Again, if you don't know what I'm talking about, don't even think about unscrewing the chassis from the headshell, 'k?

OK, Cheers again. Yeah I read all the info on the harmony site and watched the biasing vid on utube.
I'm good to go. I'll format my hard drive before I start so my wife won't know where I got the ideas from OK! LOL