I build a Solid State 12AX7 Substitute Tube. 

Among other holes, I'm sure. Hah.

Hah, well this isn't the better solid state, not implemented this way, anyway. I'm somewhere in between. I do like my tubes. Some purists take it a bit too far, they don't quite understand tubes well enough to get the most of them, and box themselves in. Like ones who insist on "original circuits" and "NOS tubes" or original tubes.

Yeah, it doesn't sound good in all applications, but there are a few where it's great. There is a company called AMT that makes sub tubes. Might be more flexible.

Hah cool, just be careful.

Thanks! I was going to say check out my first vid about it, seems you found it already.

@@DATT btw. some sneaky Russians beat you to this idea. check out the AMT 12AX7WS which is based on LND150 with some additional components to fine tune it to behave apparently identical to the real thing. also check out the vox ac10c1 which uses an lnd150 in the V1 position.

@@larrysteinke1839 Oh, I'm aware of the AMT unit. I didn't know it was LND based, I thought they used Op Amps. It looks to have a switch mode power supply on it. It's clever but not the same, probably better tho, haha. I just looked up the schematic for the Ac10, ahh, it's interesting to see how it might actually be implemented. V1 is a logical spot, cause they stages is often just a driver stage, to boost the signal and feed it to the rest of the preamp, it often does not clip and transparency is good. Mind you, I wonder how it reacts if you throw and overdrive in front of it.

Email shows I got a response from you about the LND150 in the follower, seems to be missing here. But yeah, I forget for a moment that a tube has 2 elements. I guess if the AMT unit is designed for a specific position, it does make sense they might implement an LND for the follower.

It's possible, people have tried all sorts of things. I too have noticed schems for some mods where people bake in an LND to their amp as a kind of build in OD.

Oh, not a bad idea actually.

Thanks !

Ohhh, I didn't know Jet City made those. I did hear of the AMT ones.

The Jet City RetroValves. They’re long since discontinued but they were solid state 12AX7 replacements. They came in three flavors: - Yellow had the same gain as a 12AX7 and a yellow LED. - Blue had slightly less gain and a blue LED. (Blue = cooler) - Red had slightly more gain and a red LED. (Red = hotter) I got a three-pack of each when Doug put them on clearance when he discontinued them. They’re fun to play around with. They’ll still pop up on Reverb and eBay from time to time. I haven’t broken one open, but seeing your video, I suspect they’re the same basic idea. Wire MOSFETs to the triode pins. But they probably thought to wire an LED to the heater pins, too, to give you some tube glow.

Oh, maybe a little.

Oh yeah, I'm familiar with the Red Bear. It's pretty much an 800. The extra tube in the combo is an FX loop buffer. The head is pretty much the same. The only real difference is is the cathode of the second gain stage, 800 is a 10k cold clipper, Red Bear uses a much lower value, 3.3k I think, will give the amp a bit more gain. That and the Footswitch disables the bypass caps on stage one and 2 with has the effect of cutting the gain. Not sure what that sounds like, I guess might be similar gain to a 2+0 superlead. I was always fascinated by that amp. Thought I might try modding my 800 to be like it one day. Has it been burning out the phase inverter tube ? I'm pretty sure a tube won't mind, they like being hot. Not sure how that heat would effect the LND mosfets tho.

Oh cool. Not a whole lot of info on these RedBear amps. I believe you are correct about 3.3k, although the schematic I think has a 3k there. It has more gain and bass than a 800 to my ears or maybe just not as anemic sounding. I also have the MKE60 but some of those values in the circuit are a bit different and one 470pf cap that the combo has, isn’t on the MKE60. I’m not sure about it burning out the phase inverter, but it was picking up radiating heat from the power tubes. I didn’t like that. The tone is similar to what it sounded like with a tube there though. These amps aren’t put together all that great, but with a little modding they can be solid. I just went through the entire amp swapping filter capacitors to film caps. The first tech I had work on it made a lot of errors in the wiring. Mine was a 220v and was changed to 120v. The guy wired the higher voltage side of the PT and it was just cooking everything and not in a good way. There was also a lot of mistakes in the filter cap wiring that didn’t make sense to me. I’ll have to make a video of the cap job I did. I used block style DC caps throughout the filter stages.

@@aaronsramblingreviews98 Oh, MKE, I didn't know they made a head version of the combo circuit. A schematic for the MKE schematic shows a 4.7k even. Also shows 0.1uF on the Pi to Power coupling caps, that could explain some of the extra bass. 800's have .022 there. Not sure about that 470p, would have to know where it is. This schem shows Two 1n caps in series in the tone stack, where a 470p would often be, which results is essentially the same value. Not sure why they'd do that, might be a layout choice. I really wouldn't worry about heat radiating off the powers tubes onto a preamp tube, they all run hot. Heat is how they work. Maybe if you put that a solid state module in there it could be a problem, little bit of heat shielding could be in order. Film caps ? What caps were in it before ? And the filter cap mistakes, was that done by the last guy ?

According to the marketing flyer, the combo was a design that Gibson asked for to work with their guitars. It was similar to the MKE, but some differences. I’d have to trace out all the different values to see exactly what the differences are. I do know for certain that the MKE filtering values are not the same as the combo. I had another tech work on it and help me out, but the first tech that did the replacement pt transformer and caps was the one that made errors. It’s difficult to explain, but the cap job wasn’t done exactly like the way it was in stock form. He used good caps, F&T can caps, but they weren’t necessary. A piece of fr4 board and some grommets with other axial F&Ts would have been fine. I just know it didn’t ever sound right since I got it back which was around the time I did that video on it. It sounds completely different since I went in and changed out those caps and fixed some wiring. My other tech also found a broken resistor that was also causing issues.

@@aaronsramblingreviews98 I do recall it was an import and branding for gibson. I forget the name, but it was a russian company that I guess was making these anyway, and gibson decided to import them with their own branding. I could imagine Gisbon wanting something smaller and cheaper to get some more market share. The differences are so slight, I doubt it'd make a huge difference in sound. However, that era, an FX loop was pretty standard, so I could see that being a custom request to be more competitive. The PSU is probably the least exact science in a tube amp, so it's fair game re rebuild one differently if you can get the same result. I know I have. But, if he sucks at it, and it doesn't sound right, then yeah, good you got that fixed up. These designs are so simple there is little excuse for a decent tech to mess up.

Well, it does make a unique tone. Can't say I'd be marketing these, it's nothing special. Just a hobby project. There are other companies that already make some, said to be pretty good, solid state substitute tubes.

Well, tubes def sound better than what this half assed rig can do. Ahhh, solid state, back in the day was weird, it's def better now. Not sure about digital modeling, I've almost literally never used it myself, so I can't speak to it. I dont' know how to describe it, but old SS amps just sounded flat, and dull, and they would get lost in the mix if played live against a tube amp. These days, idk. I've gotten past the point in my life where I'll claim one is better than another, I just like playing with tubes.

@@DATT Yeah, use what you like and what sounds good to you.

@@JDStone20 Pretty much, but I think if I was a seriously player, and or, recorded I would be exploring many of the newer options out there, like digital.

Hah, I guess that would be cool.

Oh yeah, this was my personal oversimplified experiment.

Ah maybe, I think there was more too them. This really isn't a proper sub as the amp internally would need adjustments to use them. Some of those tube replacements used op amps to do the job, and they just de coupled the high voltage, and ran them off the heater voltage. My buddie has one of the newer hot mods, was interesting. I just as soon use an overdrive for a marshall, or with my skills, just mod an amp out right, so I've never put thought into making a hot mod. Not for preamps anyway. I've toyed with the idea of making a 2 to 1 mod for power tubes tho. My Jet has 100w transformers, so I thought of making an adapter to run 4 tubes. Just really don't need one. Also playing with oddball tubes, I've toyed with making adapters to adapt oddball russian surplus tubes into a typical amp. I could do it, but the numbers stopped making sense cause of the complexity.

@@DATT now that is an interesting idea to make an adapter to run 4 tubes in your 2 tube amp since you have the transformers for 100w. would be easy enough just to add a couple more sockets to the amp if its really worth it, i have both the 50 and 100w models and it doesnt seem twice as loud lol the 50w is loud enough as it is. maybe if youre going to crank it to 11 it might make a difference

@@user-cy7cn7vr7l Yeah, I've considered straight up added extra sockets to the amp, but it would be very surgical, and in the end, it would be hard to service after. Realistically, for what I do, I don't need the extra power. So there is no point. Most of what I do on this channel is practical, stuff I'm doing anyway for my own needs, and I just film it. Very little is done just to make content. Especially, when you have so many amps already, if one isn't doing what you need, you just plug into a different one. hah.

I did that in a previous video. Check my channel for a video called "I jammed transistors into my tube sockets". Not sure about 6V6, I imagine if they are cathode biased, then yeah, there might just be a larger mosfet out there that can sub them.

Ahh, not really. It's not making a good connection to them, and these fets run cold to begin with.

I've considered it. I ordered some parts and even have a concept idea. Just need to feel the vibe.

Lol, yeah, its called a class d amp. If its solid state its not tube…this is all hilarious. Like converting 57 chevy to electric, then bragging about the engine, it doesnt matter at that point its no longer a tube amp. By the way i actually did replace my tube amp with class D power section for the reasons you said. I still use tube preamp

I have noticed they do not like circuit with the cathode bypass.

Ontario !

Not sure what to tell you off the top of my head, generally the cathode values of those preamp positions would have to change. In this, I pretty much just yolo bombed it into the position and see how it worked without changing anything about the amp. It either works or it doesn't, it won't sound good in all applications, but at least it can't harm the amp.

So even if I don't change any cathode values at least the amp would go undamaged? I also saw in another comment you mentioned you had an idea on power tube replacements. I'm also curious about those since I'd like to take my amp down to 2 power tubes without having to change impedance. Having 2 solid state "subsititubes" along with 2 regular tubes would be a cool experiment.

@@uselessboi2258 I'm bound to try the power tubes at some point, but I see no advantage to mixing tubes with fets. IN fact, I doubt that'd work, they probably have to be biased very differently. Go ahead and take you amp down to 2 tubes, there is no reason to not change the impedance. I do it all the time. I haven't run more than 2 tubes in any of my amps for a long time. You'd have to rebias of course. Hell, you can keep the same impedance if you want, as long as you aren't running to too loud.

Probably not loud enough to have more gain, but I'll usually be using an Overdrive pedal.

I didn't want to do that for indexing reasons. Otherwise you could accidentally put it in the wrong way, and I def have some amps where I can't see well the socket and have to insert by feel.

I want to say, nothing, which is why they invented solid state amps, but I guess, if you are trying to retain the character of an OT, well, you don't need 400+ volts to to that. I have yet to try replacing the power tubes, tho I do have what I need to do it, but for preamp tubes, tho' this works it's not idea, the amp would need some fine tuning and re voicing to work with them properly. I cant' speak for Power tubes. For some applications it makes sense cause we jsut want a clean tight output section and dont' want power tube distortion. I'm really not sure how much an OT adds, I want to just say, if you don't like playing with glass just go SS or digital. I'll try it eventually.

@@DATT I play solid state and tubes. I’m just curious why they hybrids aren’t happening. The OT under guitar loads exhibits frequency dependent damping at the extreme low and high end. It’s like a midboost with an absurdly wide Q, that’s crazy touch sensitive. It’s a subtle thing, but it’s infinitely more what is responsible for the “Tube Sounds” than the tubes themselves. Even EVH approved of replacing some of the tubes in his new amp with transistors because he believed that the transformer was the source of the “magic.”

@@DATT Thanks you for such a fast and clear reply!

@@subjectt.change6599 At the end of the day, from a corporate stand point, it's horribly inefficient, adds to the cost for not a lot of gain, which cuts intro shareholder dividends, when they can get you like 90% there with just a good design using cheap parts. We live in an era where no company that is publicly traded is capable of actual innovation or risk. I'd be interested to look over some of those EVH schematics (good luck). If there is a market and it does add, well damn, someone will make it, but I think the market for people who don't want tubes is just moving in a very difference direction. Cost is important to most people it seems, many people who run tubes amps don't' even understand them or are using them properly for this reason. I can agree the power tubes them selves are maybe less important for a tube tone, than the preamps, especially for modern tones. Admittedly, being a smaller channel still, I can engage with the audience at this level.

@@DATT I dig your channel, and I appreciate your insight. Thank you.

That did seem to be one of the positions that made sense, especially on high gain amps.

Ah, no I can't, I've never tried subbing an EL34 before. My guess is a mosfet would have to be biased very differently, and if you don't it just insta flows way too much current.

Ah, no, I've never done that before. Not sure how.

Which transformer did it burn again ? Input or output ?

Maybe . . . hah, these puppers react funny to certain circuits.

Yeah, mostly joking ;-)@@DATT

@@tzed2509 Ahhh, hah, ok. Hard to tell on here sometimes. And like, it could actually work.

@@DATT better safe than sorry as they say, in terms of comments. Not sure how safe these would be in a hi-fi circuit... only one way to find out!

@@tzed2509 Ahhh, they meet all the 12ax7 specs, so basically, I worst case it just won't sound good. These things seem to sound bad if that stage has a sizable bypass cap on the cathode. They don't like that.

LND150

I might be able to answer a few.

Like this, they don't really make them, cause it's a poor implementation of the idea I threw together for the lols. There is a company called AMT Electronics, that makes pedals and stuff that has a SS preamp tube sub. I've never tried one however.

@@DATT cool thanks dude I’ll check it out!! I moved to Thailand so I’m basically looking at super budget/DIY stuff a lot more than I used to, even though I used to before haha

@@Metaltrippin2 Oh wow eh. I'm never sure what to tell people who are not in the US or Canada. That company is Russian tho, so they must be able to sell internationally, but, I don't know if I would consider it cheap. IF you're confident with the high voltages, you could check out my out vid about this "I jammed transistors in my tube sockets" maybe that'll give you some ideas if you can score just the LND150's/

@@DATT okay thanks man also are there any “solid” resources on solid state amp modding ? I have a 1x12 I want to convert into a cab but also rehouse the amp as a mini head. Thanks man

@@Metaltrippin2 Umm, not really. I haven't don't any SS amp modding really. I know just enough about op amp preamp design I might be able to mod one, but it's never come up. I think I know enough about SS that if I have a schematic I could repair one. But no, never really modded on one.

Hmm, I hadn't considered in a mic. Looking at the schematic quickly, I don't think it'd hurt to try, but the circuit in a mic is a lot higher tolerance than a guitar amp. Guitar amps work using controlled chaos, using the tubes to make an intentionally distorted sound, where as a mic tried it's hardest to have the cleanest sound. If it was me, I'd just use the mic as is, buy it a new tube, like, it's going to last a while right ? I would try a tung sol 12ax7 or maybe their 5751. I would avoid JJ tubes for that application. If you really don't want a tube mic, I would just flip it and get a solid state Large Diaphragm mic instead. There is really no sense in modding it to be Solid state, where there at many excellent SS mics out there.

@@DATT You are 100% right... No point to mess around with that mic... I'll buy a new valve and sell it. Thank you

@@DATT They say that the original valve is a 12AX7/ECC83... Is it the tung sol that you are talking about ?

@@yanudol Yes, the Tung-Sol 12AX7. They tend to be a good one for this sort of thing.

Are you referring to the weird looking gold circle cage looking thing mounted near the can caps ? That's a bias pot. I removed the internal bias pot, and mounted on the outside so I could bias the amp for different power tubes without having to take it apart. That cage thing used to be a heat sink fan computer part, I gutting out the fan and a little pot if in there nice. It let me do this mod without having to drill a hole in the chassis.

Yeah, I must of been testing a computer. I work one them too sometimes.

You can't might not sound good. Check another video I have called "I jammed transistors in my tube sockets", in which I did essentially that. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-VYPzzhX6CFc.html

I do in future vids. End up with a small cab off camera that lives with a mic on it.

Ouch, any idea what went wrong ? I would imagine a mosfet would bias very differently than a tube. You recall the part number of the mosfets you were using ?

Yeah you've mentioned.

It was hit or miss for some things.