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#1
My first 100% original tube design. A low voltage pre-amp that uses two 12AU7 tubes, I call it "The Hood". "The Hood" is basically a big glorified stompbox/preamp. "The Hood" evolved from my medalings with low voltage 12AU7 tube stompbox design.

It features an all tube signal path. It has controls for volume, gain, body, tone and presence. The body controls essentially affects how scooped or flat the mid range is. The unit features a switch labeled clean/dirty. This switches in different cathode resistors and biases stages differently. Gives you a nice clear tone or a semi dirty gritty tone. The gain pot is also pulls out for a "gain boost". This gives ya a crunchy, saturated tone.

The heaters are run at 12V DC while the plates see 24V DC.

"The Hood" also features relay bypass system. It is true bypass but instead of a mechanical DPDT or 3PDT switch it uses a DPDT 12V DC relay. This allows external switching from a tiny little control/stomp box that you can hook to the back of "The Hood". This will allow one to bypass "The Hood" external ie. from one side of the stage if its on the total opposite. As well as switching between bypass and the pre amp the relay also turns on a bright red LED mounted on the front panel. The LED only turns on when the signal goes through the pre-amp. The bypass is done remotely by a small footswitch that connects to the back of "The Hood" with a standard 1/4" guitar cable.

It sounds just amazing. The knobs are all very interactive, epically the volume and gain control. "The Hood" is capable of having tons of headroom, on the other hand it gets nice and thick and dirty with the right settings. The clean/dirty switch adds a nice bit of grit and bite when you need it. The "pullable" pot adds a nice tubey crunch sound. I love the tone controls, the body and tone provide endless combinations of sounds. The presence is subtle yet allows you to dial in just the right amount of high end, perfect when you need to tame that distorted tone to something a bit softer.





More pics, as well as schematics, talk and circuit talk on my site. http://www.pdfelectronics.com/the_hood_a_custom_pre_amp_design.htm

Anyways had to show it off, I am very proud of it.
#2
looks pretty damn fine bro
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#3
gona make any more?
The Best Floyd Rose Is A Setup Floyd Rose!

Gear:
STARcaster Strat
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03 B.C. Rich NJ Warlock Speedloader
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Marshall 1960B
#6
sound clip?
I play Lacrosse, you should too
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#9
I'm a bit confused. Is it a tube pre/SS power amp, or is this like a giant stompbox? In any case, it looks pretty sweet.
Schecter Gryphon; Ibanez AEG20E
Peavey Rage 158 ; TRAYNOR YCS50
EHX Big Muff Pi; Dunlop CryBaby GCB-95 (modded); MXR M-108 10-band; DigiTech JamMan Looper
#10
Third sentence...

"It is basically a big glorified stompbox/preamp."

The idea is you use it for a "tubey boost or tube distortion". It has an all tube signal path. The idea is you put it between your guitar and amp to liven things up. You can place it on top of your amp or in your rack then bypass it remotely.

No poweramp. Read the article on my site if confused, lots more info there.


Thanks guys!
#11
Ah, I understand now... And yeah, I did read your mini-wall o' text, I just... forgot. I have a bad memory.
Schecter Gryphon; Ibanez AEG20E
Peavey Rage 158 ; TRAYNOR YCS50
EHX Big Muff Pi; Dunlop CryBaby GCB-95 (modded); MXR M-108 10-band; DigiTech JamMan Looper
#12
Willing to post a schemo? I'd like to see what you have going on there...

EDIT: by the way, good call on the 12AU7 at low voltages, the 12AX7 defines "crap" at low voltages...
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Last edited by DLrocket89 at Feb 22, 2009,
#13
Check the website he linked to
Schecter Gryphon; Ibanez AEG20E
Peavey Rage 158 ; TRAYNOR YCS50
EHX Big Muff Pi; Dunlop CryBaby GCB-95 (modded); MXR M-108 10-band; DigiTech JamMan Looper
#14
Quote by BD 425
Check the website he linked to



I fail, sorry. :stickpoke
Quote by kcdakrt
DLrocket89 makes my ug experience better!


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#15
Are the second and 4th stages actually mu followers as the schematic indicates?
Quote by kcdakrt
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Kit Amp Building Tutorial
#19
And you can get a clean signal out? Normally anything over a few volts gets clipped with that arragement...Vg is so close to Vk that there isn't room for signal to get through unclipped.

Never tried said arrangement in a low-voltage unit though, maybe that helps things some.

Whatever, rock on, well done!
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DLrocket89 makes my ug experience better!


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#20
I don't know the technically terms but yeah I did know that no cathode resistor meant much more clipping. Its done a lot with low voltage 12AU7 arrangements Ive noticed.

I played with the design for a low time on the breadboard, and I came up with that arrangement. The unit is actually quite clean when dialed in. Its not high gain though. Its the perfect gain spectrum for me.

Been playing it all morning, sounds great!
#21
how much was it too make?
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#22
No idea...

I had the caps, resistors, jacks, relay, well all the passive components.

The enclosure I think I spent $15. Transformer I got from school. Tubes I got 8 NOS 12AU7 in a little trade.

Hard to say how much it cost, not much, probably under $50.
#23
what if you bought it all new?

ive been wanting to do a project like this for a while >.>
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#25
This is excellent. Just finished soldering a few more capacitors for your DS-1 mod and it's sounding lovely at the moment. Just C13 and C3 to go (as well as the diode if I fancy doing that).

Are you gonna be uploading sound clips of this in the near future? I'd love to hear it.

If you design a tube poweramp in the near future I will fancy having a go at building it so please consider it
#26
Soundclips:

All clips using a tele I built into a crappy Randall SS amp (crappy SS amp makes the unit sound better and shows the difference). Used both bridge and neck pickups. The EQ on the amp had bass flat, mid slightly scooped and treble boosted a wee bit.

Amp has a lame mushy sounding Celestion in it.

Recoded using a Shure SM57 using a Toneport as the recording interface. Toneports modelling and stuff was bypassed, no effects or mixing added after the fact...

Stll very new to recording and havent quite got the hang of it yet, o well...

Clips broken into four parts
1. Dry signal
2. Hood engaged, showing its cleaner tone and how the dynamics of ones playing affects the sound.
3. Slightly dirty sound, light drive.
4. Heavier sounding distortion than 3.

http://www.soundclick.com/bands/page_songInfo.cfm?bandID=649289&songID=7368612
(might have to disable pop-up blocker if you have one)
Last edited by kurtlives91 at Feb 24, 2009,
#28
Sounds very good man. When you first turned it on dirty it sounded really great, just a nice little crunch.
Gear
Fender Thinline Telecaster Deluxe

1983 Aria Pro II XX Deluxe Flying V

2007 S101 EGU34

1963 Kay Vanguard

1964 Kay Vanguard

AXL Badwater SRO

Hondo Strat

1974 Acoustic(brand) 134 4x10 combo

Epiphone Valve Jr.
#29
Thank you for taking the time to listen and comment!

I to like the dirty sound. Just when its on the verge of breakup, adds a bit of bite and crunch. Wasn't happy on how the final part of the clip sounded on record but that's pk.
#30
The third setting is great to me. The 4th sounds like the bass is a little mushy, but it is still a great sounding preamp. This is a great blues box. I have a question though. How much drive can you get out of this thing? Will it push the the preamp of another amp into overdrive as well?
#31
Quote by end_citizen
The third setting is great to me. The 4th sounds like the bass is a little mushy, but it is still a great sounding preamp. This is a great blues box. I have a question though. How much drive can you get out of this thing? Will it push the the preamp of another amp into overdrive as well?

Ya as I mentioned before I am not happy with the forth sound either. I think its a combination of my "el cheapo" 12" speaker and my mic placement. Maybe I could call that slight muss tube sag? hahahahah

O yes this can push another pre-amp into saturation. It has a ton of output.

Can get pretty heavy though I cant comment much on that cause I never really play that style.
#32
Quote by kurtlives91
Ya as I mentioned before I am not happy with the forth sound either. I think its a combination of my "el cheapo" 12" speaker and my mic placement. Maybe I could call that slight muss tube sag? hahahahah

O yes this can push another pre-amp into saturation. It has a ton of output.

Can get pretty heavy though I cant comment much on that cause I never really play that style.


Nor do I. I was just curious. Have you tried it through another amp:speaker combo? I'd like to know what this sounds like in front of your VJ, or maybe the randall through the VJ's speaker (assuming it is of better quality).
#34
I have a full, labelled vero layout for the relay bypass switching which is very clear.

The rectification filter section I just made on the "fly" so no layout for it.

I have a vero layout for the actual tube signal path. It is a bit unclear but one could build from it.

Wanting them?
#35
I am if you don't mind.
Epiphone Valve Junior
Peavy Windsor Head
Ampeg J-12T
1959 Harmony H400A
Randall Pro-Tube 2000

Gibson Faded Special SG
Homemade superstrat with EMG 81
Peavy Tracer
Washburn XB600 6-string bass
Enough pedals to crush a rhino
#37
Added them to my photobucket

http://smg.photobucket.com/albums/v610/kurtlives/

You will have to follow the schematic to makes sense of the signal path layout. Or if you actually wanted to build it I could label it and make it more clear. It only makes sense to my crazy mind right now...
#39
I like the sound overall. As stated the fourth option is a bit iffy, but still doesn't sound bad. I like a touch more gain in my setup, but from a sound tech's perspective it sounds very good.
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#40
pretty sweet.

i like the first three sounds, but yeah, that fourth got a little sludgey..

you said thats probably due to the cheap speaker and mic placement, hows it sound when you have it at high(er) gain settings on a better amp?
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