Tube device w/ line level output

[LarsXI]

Howdy

I'd like to be able to send my signal into some tubes before sending it into the audio interface of my computer. Basically, I'm looking for tube sounds at line level output. So I need an approximation of a tube amp but I don't want to drive a speaker.

Would a small hybrid project such as the ruby tuby work here?
http://www.sophtamps.ca/mambo/index.php?option=com_content&task=view&id=28&Itemid=39

Or should I look into a pedal project?
http://amps.zugster.net/articles/tube-pedals

Ideally, I'd like to be able to get clean tones out of it


Thanks

[frequencycentral]

http://www.diystompboxes.com/smfforum/index.php?topic=70524.0

[Minion]

I built one of these recently and it sounds awesome with my 15band EQ on the output....

http://www.paia.com/prodimages/siabsch.pdf


It has speaker simulators and an Active DI and FX Loop and uses a 12ax7 Dual Triode with an opamp to help overdrive it.....

You can build it with the features you want and leave out the ones you don"t...I built mine from a kit and modded it pretty extensively and sounds great for recording or through a power amp....

Cheers

[Zben3129]

You could always build a lineout box and attatch that to a tube amp for the real tube sound. Lineout - cab sim - computer. And of driving a speaker is a problem then you could just use a dummy load.

Zach

[PerroGrande]

I think the Real McTube is an interesting project that produces what I would consider a classic tube sound.  It is not, however, a beginning circuit (no offense intended by this comment -- I have no idea where your comfort level is with these builds).  It does contain voltages that are non-trivial and needs to be built with that in mind.  It is also sensitive to construction, wiring, layout, grounds, etc, etc.  The circuit is simple enough that it lends itself nicely to some mods -- adding a tone stack, making it a clean boost or clean pre, etc.

I'm not that big of a fan of the various "starved plate" builds, but some of the circuits that use tubes specifically designed for lower voltage operation can sound pretty good, at least to my ear. 

[sean k]

My ideal for this kind of stuff is tubes at the beginning and tubes at the end... but only on the mids and up as I reckon lows work better through transistors.

I've got a tube pre from the london power book and it's just warm. meaning I suppose that the inclusion of 2nd order distortion is what tubes do well, when they are clean.

I did lots with the Real McTube and it offers a little more dirt but even then nothing like a bunch of power tubes running all out into a somewhat saturated OT and then alnico magnetted speakers 

I always found that the tube things kinda problematic in the sense that when you get a nice warn tubey sound it also happens that the noise floor is somewhat higher than you might want. That Paia pre looks really good and I think I'll have a go at that simply 'cause I've never tried starved plate and have always opted for HV simply 'cause we have 240VAC in the wall so it's real easy to get 300+ with a coupla 240/12VAC's back to back... for preamp duties.

Now that recent post with the Beatles preamp looks like it'd be a nice candidate for a pre. EF86 for voltage amp and a dual triode, E88CC was it?, in parallel for current amping... very nice.

[Minion]

Actually the PAIA kit runs the Plate off of 45v dc , It uses a CMOS Hex inverter to triple the voltage to 45v , it is starved plate but much less starved plate than a 9v tube design....I moded mine a bit, I used fet opamps at the input and increased the gain 1000% on the first opamp stage to really overdrive the tubes....

I actually use mine as a Guitar amp , I have it racked up in a Chassis with a 15 Band eq (Not DIY) and a 100W Mosfet power amp (Totally DIY) , it sounds freaking awesome , especially if you like a really heavey distorted sound , with the 15 band eq and the speaker simulations you can dial in any number of sounds....

It"s not a pretty guitar head but here is a pic anyways...




Cheers

[LarsXI]

Yeah, I'm sticking to lower voltage for now. I wouldn't rely on it for real high gain stuff, just some moderate grit. The idea is that I'll be able to use it with treble boosters and put my fuzz-boxes in front of it and warm things up. yeah, warmth.

PentaBoost looks nice and simple. The question is how much mileage would I get with it as the only tube in the chain.

That paia with the eq looks impressive. At that point, I say don't worry about it looking pretty, just celebrate the ugliness. Looking at the website, it seems the s.i.a.b. has a lot of what I'm looking for. Thanks for the lead.

I may eventually throw together a ruby tuby just to see what I can do with it.

and thanks for the insight, everyone. greatly appreciated

[PerroGrande]

The PAiA does look interesting, and the voltages are more manageable for one less experienced with tube builds.  It looks moderately more complicated than the base McTube build, but a lot of that is in the tone control and the CMOS inverted voltage trick.  Looks like another fun build!

[Ronsonic]

I built a one-tube guitar amp that might lend itself. I used a 12DW7 with the high mu half (equivalent to half a 12AX7) for gain followed by the low mu section (equivalent to half a 12AU7) loaded by a Fender reverb driver tranny. Puts out just over 1/2W into 8R. The output level should be convenient for most line level application. I don't recall all the values, but could look it up. Wouldn't be hard to just breadboard it together and develop from scratch either. Mine lives in a cigar box with headphone, line and speaker outputs.

It lacked gain as a guitar amp and really woke up with a pedal in front of it. You won't really need much/any gain so it might work fine for you. In fact, you might be better off using a 12AU7 with one half for drive and the other for output.

[Ben N]

Try a Dumbleator, but with the two sections reversed--the gain stage to bring your signal level up, followed by the cf to lower the output impedance, with the pots in there to keep the signal from clipping. Or let it saturate a little--I used a Vox V941, basically the same idea, to add a bit of warmth to a cold, clean amp.

(For a non-DIY solution, you can get yourself an Art MP tube mic preamp. Cheap, done.)

[LarsXI]

I built a one-tube guitar amp that might lend itself. I used a 12DW7 with the high mu half (equivalent to half a 12AX7) for gain followed by the low mu section (equivalent to half a 12AU7) loaded by a Fender reverb driver tranny. Puts out just over 1/2W into 8R. The output level should be convenient for most line level application. I don't recall all the values, but could look it up. Wouldn't be hard to just breadboard it together and develop from scratch either. Mine lives in a cigar box with headphone, line and speaker outputs.

It lacked gain as a guitar amp and really woke up with a pedal in front of it. You won't really need much/any gain so it might work fine for you. In fact, you might be better off using a 12AU7 with one half for drive and the other for output.

Thanks for the offer, that sounds like it would be excellent, but I'm in unfamiliar territory as far as from scratch development goes.



The dumbleator looks like an achievable affair. Reading elsewhere suggests it's rather flexible, highly configurable with the send/receive bit. Thanks.

Also, the PentaDriver is beginning to look interesting.
http://experimentalistsanonymous.com/board/viewtopic.php?f=5&t=1727
Seems rather versatile for the simplicity of the circuit.

[Ronsonic]

I'll pull it out and measure, easier than finding whatever scraps of paper it was "designed" on.

[frequencycentral]

Also, the PentaDriver is beginning to look interesting.
http://experimentalistsanonymous.com/board/viewtopic.php?f=5&t=1727
Seems rather versatile for the simplicity of the circuit.

There's a Pentadriver thread on this forum too: http://www.diystompboxes.com/smfforum/index.php?topic=70533.0l

[Ice-9]

I built one of these recently and it sounds awesome with my 15band EQ on the output....

http://www.paia.com/prodimages/siabsch.pdf


It has speaker simulators and an Active DI and FX Loop and uses a 12ax7 Dual Triode with an opamp to help overdrive it.....

You can build it with the features you want and leave out the ones you don"t...I built mine from a kit and modded it pretty extensively and sounds great for recording or through a power amp....

Cheers

I have just been checking this circuit as i would like to build a valve preamp overdrive pedal. I was looking at the part of the circuit based oround IC3 and its caps and diodes, IC3 is an inverter chip. Am i correct in assuming this is just a simple voltage doubler circuit on the +15v rail, and can i use any voltage doubling (ie my own)

[Minion]

Yes, IC3 is a Cmos hex inverter used as a voltage tripler, I suppose if you have enough current available you could just use a regular Capacitor/Diode voltage tripler and not use the CMOS Chip.....

You could also run the tube plate off of 150V DC quite easilly by connecting Two 120v Primary 12v secondary transformers Together (connect the second transformer to the first backwords) which will give you 120v AC out of the second transformer to run the Plate voltage and Tap the first Transformer for the Heater Voltages and the IC Supply....


Cheers

[Ice-9]

Thanks Minion, Thats what i thought although i did quickly look at the schematic and thought it was a voltage doubler as it says 30v. I am happier it is a tripler as 45v is a better voltage to be on the B+. One other question i have relates to the resistors.  R4 has no value on the schematic at a guess i would say a bit lees than R5 possibly 220K ? . The values of the resisitors marked 2700 i assume 2k7 (2700 ohm) and the wattage of the resistors R1 R4 R5 R30 R31.
Thanks

[Minion]

Hi, R4 is the same as R5 (270K) and all resistors are 1/4 w.....2700 is 2k7.....Also the PSU actually puts out +15 and -15v , I don"t understand how they get +/-15 from a 12v transformer but they do....

Cheers

[Ice-9]

Thanks for the extra info.

The 12v ac input has  rectification with the 2 diodes, giving half wave rectification on each side effectively giving +/- 12v but smoothness would be poor.  it looks a little strange as there is no centre tap in the wall wart as you would have with a transformer psu. A bit puzzled myself, i would expect to beable to work it for maybe +/- 10v. But psu desng is my weakest point.

[Ice-9]

@Minion.
I have just breadboarded the psu using a 16v ac adapter i have. I didn't have the 100uf caps or 330 ohm resistors but it does indeed work. The 16 ac gives +/- 28v dc or 56v together. As i thought using half wave rectification does indeed give an unsmooth rail. Also i only had 1uf caps which don't help the smoothness. To use full wave rectification you would need to use a center tapped transformer. Sorry i just realised this is a bit off topic with the original post.

I MUST CORRECT i said it is half wave rectification but it IS full wave rectification. So in reality the first part of the psu is actually a full wave voltage doubler, with a center tap. Can some plz correct me if i am wrong.