Welcome, Guest. Please login or register.

October 26, 2020, 08:30:06 AM

Login with username, password and session length

Recent Posts

 

Author Topic: My new hybrid- demo and schematic  (Read 10827 times)

Steve Conner

  • Regular
  • **
  • Posts: 23
  • Chip Points: 8
  • somebody squished mah trannies!
    • View Profile
My new hybrid- demo and schematic
« on: January 29, 2011, 10:17:28 AM »
Hey all

I normally hang out on the MEF, but I thought I would cross-post this here. I've been building amps for years, and the whole time have struggled with the questions: Is there really anything bad about transistors? Is it possible to make a good sounding hybrid? Well, after all those years of experimenting, here is my answer.

http://scopeboy.com/scopeblog/?page_id=96 - full story behind the project

http://www.youtube.com/v/DZigVupYve4 - demo video

http://scopeboy.com/scopeblog/wp-content/uploads/2010/12/ninja-corvette-demo-hq.mp3 - better quality version of video soundtrack

http://scopeboy.com/scopeblog/wp-content/uploads/2010/12/NinjaCorvetteHybrid.pdf - schematic

I'm working on getting rid of the remaining tubes.  :trouble

I was partly inspired by RG Keen's guide to the old Thomas Vox SS amps. If you squint at my output stage in the right light, it looks like an old Thomas Vox or Leslie, except with current limiting and a proper bias scheme. And I probably got some ideas from Teemu Kyttala's book, too.

tonyharker

  • Elite
  • ****
  • Posts: 150
  • Chip Points: 19
    • View Profile
Re: My new hybrid- demo and schematic
« Reply #1 on: January 30, 2011, 04:47:27 AM »
Your link to the schematic is not working, can you fix it please as Id like to try this on one of my amps.
Thanks  Tony.

phatt

  • Legendary
  • ******
  • Posts: 2141
  • Chip Points: 261
    • View Profile
Re: My new hybrid- demo and schematic
« Reply #2 on: January 30, 2011, 07:31:29 AM »
Hi Steve,
             Your Valve section may need some fine tuning.
i.e. add some series resistance after each triode,, you've got some ugly blocking type distortion which is destroying the sound. (but if that spitting distortion is to your taste then go for it.)

You may wish to look at the redneF Pro Junior preamp setup for some good ideas.
Or even some early Deluxe tone circuits might interest you.

Other than that It's a *Very clever idea* and good on you for having a go.
Thanks for sharing your ideas. :tu:

If it interests you I have had good results by power soaking a small PP Amp and ReAmplifiying it via a simple voltage divider setup and then into a large 120Watt SS Amp. (You get to do post power tube EQ effects that way)
Cheers, Phil.

Steve Conner

  • Regular
  • **
  • Posts: 23
  • Chip Points: 8
  • somebody squished mah trannies!
    • View Profile
Re: My new hybrid- demo and schematic
« Reply #3 on: January 30, 2011, 07:38:25 AM »
The link works for me.
I've included the schematic as an attachment, maybe that will work.

Re the sound: That was what the original amp sounded like. It is a bit ratty. No super-saturated modern gain there. :) You have to listen to the MP3 version of the soundtrack to judge it, because the camera mic is distorting too.

I was taking it apart today anyway, so I shortened some of the time constants in there to try and tighten it up a bit.

I've done the power soaking and reamping many times. It was experiments like that that persuaded me to give solid-state a try. But this is different. It's simpler and it all fits in one box, plus it gives a highish impedance drive to the speaker, like a tube amp or the Valvestate power amp.
« Last Edit: January 30, 2011, 07:41:49 AM by Steve Conner »

J M Fahey

  • SSGuitar Global Mod
  • Legendary
  • ****
  • Posts: 4142
  • Chip Points: 429
    • View Profile
Re: My new hybrid- demo and schematic
« Reply #4 on: January 30, 2011, 07:46:47 AM »
Hi Steve, first of all thanks a lot for sharing with us your famous, yet mystery Hybrid amp. :tu:
As often happens in similar cases, I had mentally "designed in my mind" what I thought you were doing.
Man , you went way beyond that !!!!!!!  xP
I had imagined a much simpler version, an EL84 straight into a Thomas Vox interstage transformer (with proper impedance ratio, of course) driving (why not?) a couple ASZ15's or some modern silicon thingies.
Yes, it would have had some crossover or thermal runaway problems.
Your bias supply alone looks like something Hewlett Packard would use in some lab equipment. :tu:
Besides the Videos, can't you post some straight MP3? I trust them more than a Video's audio track.
As far as "Tubes", I have a very open minded opinion about them, they are not "magical" at all; just amplifying devices which by a quirk of their DNA have some "defects" which turn them into non-linear processors which happen to do "nice things" to our music.
If somehow we can faithfully reproduce those "defects" with some other elements, be they FETs, bipolars, Op Amps with non linear feedback, whatever, we won't need them any more.
Good luck with your project and keep posting.
And yes, *this* is the approppriate Forum to post these :loco  :duh things. ;D

Steve Conner

  • Regular
  • **
  • Posts: 23
  • Chip Points: 8
  • somebody squished mah trannies!
    • View Profile
Re: My new hybrid- demo and schematic
« Reply #5 on: January 30, 2011, 08:03:30 AM »
Hi JM!

There should be a link to an MP3 in my first post. It was recorded at the same time as the video, but using a handy recorder with a stereo condenser mic. I will do some more, the next time I can book some time in the studio at work.

As for the interstage: I realised that if I used complementary output transistors, the interstage would only need one winding, so I could use an ordinary Champ output transformer.

For my next build, I'm going to combine it with a solid-state preamp and "PI", and use a small toroidal mains transformer as the interstage. I'm aiming for a clone of a Bassman or Marshall 2203. We'll see how that sounds. :)

Tone is definitely subjective. I liked the tone of the amp, and thought it had a bit of Clapton's Beano mojo. (Not with a Strat, mind you.) But I guess plenty of people don't like the Beano tone, either.

J M Fahey

  • SSGuitar Global Mod
  • Legendary
  • ****
  • Posts: 4142
  • Chip Points: 429
    • View Profile
Re: My new hybrid- demo and schematic
« Reply #6 on: January 30, 2011, 08:27:34 AM »
Hi Steve, now I've been able to hear it.
I like it very much up to 4:15 ; up to that point it has incredibly crystalline sound, and when it clips, yes, it's somewhat buzzy , but *tube* buzzy, which I like.
Personally, I like sound with "edge"
Besides, my personal experience is that it stands out through the "ball of sound" onstage.
Then, for about 20 seconds it becomes fuzzy in an SS (Fuzz Face?) way, dark and undefined, what did you do then?
Then there are a few short snippets where I like the sound, distorts more like a tube stage full driven.
In all, an excellent experiment.
I see much potential there, absolutely the opposite to the Valvestate (and many others)  approach which distort a tube very far away and removed from the speakers.
Little reaches it !!!
I think that lacking tubes in the output, best second option is having them in the first next step backwards in the sound chain, and making sure that that last SS stage respects the tube sound being offered to it, in the widest sense of the word.
I see both you and Phatt have been careful about this last requirement :tu:
And keep cranking out these wonderful  :loco :duh designs or you'll see !!!  :trouble :grr

 ;D :lmao:

PS: I loved the Presentation Speaker trying to impersonate a Scot.
Er .......  it wasn't an actual Scottish Engineer speaking, was it?
 ;)
« Last Edit: January 30, 2011, 08:31:18 AM by J M Fahey »

Steve Conner

  • Regular
  • **
  • Posts: 23
  • Chip Points: 8
  • somebody squished mah trannies!
    • View Profile
Re: My new hybrid- demo and schematic
« Reply #7 on: January 30, 2011, 08:51:08 AM »
Hi JM,

At 4:15 I put the neck and middle pickups both on. That gives the kind of phasey, mushy Strat sound that many people just find annoying. :) I did it because that's what Bill Perry does in his version of Little Wing that appears on "Live In NYC". :) Also the output stage is getting clipped really hard at that point, maybe too hard.

If you like a more edgy sound, you'll probably find that you start to like it again when I switch back to the bridge pickup.

mensur

  • Master
  • ***
  • Posts: 94
  • Chip Points: 5
    • View Profile
Re: My new hybrid- demo and schematic
« Reply #8 on: January 30, 2011, 10:16:14 AM »
Hi Steve,
             Your Valve section may need some fine tuning.
i.e. add some series resistance after each triode,, you've got some ugly blocking type distortion which is destroying the sound. (but if that spitting distortion is to your taste then go for it.)

You may wish to look at the redneF Pro Junior preamp setup for some good ideas.
Or even some early Deluxe tone circuits might interest you.

Other than that It's a *Very clever idea* and good on you for having a go.
Thanks for sharing your ideas. :tu:

If it interests you I have had good results by power soaking a small PP Amp and ReAmplifiying it via a simple voltage divider setup and then into a large 120Watt SS Amp. (You get to do post power tube EQ effects that way)
Cheers, Phil.
Phil can you post the schematic of that, it;s very interesting?

tonyharker

  • Elite
  • ****
  • Posts: 150
  • Chip Points: 19
    • View Profile
Re: My new hybrid- demo and schematic
« Reply #9 on: January 31, 2011, 05:20:10 AM »
Hi Steve I've now got your schematic, must have been a glitch with my Acrobat reader, as it was showing just a black screen.  Im a bit puzzled, your circuit shows the boost transistors in emitter follower mode fed from the output transformer.  How then can you get 30 watts out of them if there is no gain in the circuit?   EF circuits have a gain of less than one and you are still using an 8 ohm speaker.  You would need to amplify the output from the transformer (ie 3w in 8 ohms is about 5vrms to 30w in 8 ohms is 15.5v approx) by about 3x ???

Steve Conner

  • Regular
  • **
  • Posts: 23
  • Chip Points: 8
  • somebody squished mah trannies!
    • View Profile
Re: My new hybrid- demo and schematic
« Reply #10 on: January 31, 2011, 09:32:38 AM »
In 30 watt mode, the grounded end of the OPT gets lifted off ground and connected to the speaker output.

You can look at this in one of two ways:

The voltage gain is achieved by bootstrapping, or:

It's not an emitter follower any more, but a common emitter amp. (To visualise this, ground the speaker output and float the other end of the speaker, where it joins the power supply smoothing caps. Same circuit.)

This was a trick to allow me to use a standard valve amp OPT.
« Last Edit: January 31, 2011, 09:35:54 AM by Steve Conner »

J M Fahey

  • SSGuitar Global Mod
  • Legendary
  • ****
  • Posts: 4142
  • Chip Points: 429
    • View Profile
Re: My new hybrid- demo and schematic
« Reply #11 on: January 31, 2011, 09:35:19 AM »
Hint: they are not emitter followers.

EDIT: oh well, another simul-posting.  :(
Maybe I should re-write this sentence, or Mesa will sue me for infringing their Simul-class patent. ;D
Edit2: it's plain old common emitter, because signal is applied base-to-emitter , and not base-to-common_ground.
It works because the driver winding is floating, so transistors provide voltage gain, the works.
Congratulations, Steve.
« Last Edit: January 31, 2011, 09:42:01 AM by J M Fahey »

Steve Conner

  • Regular
  • **
  • Posts: 23
  • Chip Points: 8
  • somebody squished mah trannies!
    • View Profile
Re: My new hybrid- demo and schematic
« Reply #12 on: January 31, 2011, 09:38:00 AM »
Ha! Ninja simulpost!

I'm spreading confusion on the intertubes and loving it. 8)

The idea comes from a Douglas Self paper where he proved that CC and CE output stages are the same, just with a different reference for the input signal.

joecool85

  • SSGuitar Admin
  • Legendary
  • ******
  • Posts: 3327
  • Chip Points: 991
  • SSG Creator
    • View Profile
    • thatraymond.com
Re: My new hybrid- demo and schematic
« Reply #13 on: January 31, 2011, 10:13:19 AM »
I normally hang out on the MEF...

http://scopeboy.com/scopeblog/wp-content/uploads/2010/12/ninja-corvette-demo-hq.mp3 - better quality version of video soundtrack

...

I'm working on getting rid of the remaining tubes.  :trouble

Welcome to the forum!  Where/what is MEF?

Nice project you have going, it sounds really good.  Let us know when you get the other tubes out.  It makes me nervous that musicians on the whole rely on tubes that are now only produced in China and Russia...and with smaller and smaller quantities each year!

**edit**
Also, I really like the youtube video.  It's always cool to see things in action.
« Last Edit: January 31, 2011, 10:19:41 AM by joecool85 »
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

Steve Conner

  • Regular
  • **
  • Posts: 23
  • Chip Points: 8
  • somebody squished mah trannies!
    • View Profile
Re: My new hybrid- demo and schematic
« Reply #14 on: January 31, 2011, 10:37:08 AM »
Hi joecool!

The MEF is music-electronics-forum.com - what started out years ago as "Ampage".

There are a lot of great engineers, techs and amp builders over there, but they mostly can't see past tubes. I love tubes, but like you, I can't see a long-term future for them. So I thought it was a great idea to create a forum that focuses on solid-state. In the long term I would love to see SS boutique amps that hold their own against high-end tube ones. But only in blind tests, where the cork sniffers can't see the absence of tubes. :)

Re JM's Hewlett-Packard comment, I actually do design scientific instruments in my day job. I've never worked for anyone as big as HP/Agilent, though. I found a niche doing custom instruments for really bizarre applications. Right now I'm working on a DSP for sniffing out faults in high-voltage cables. :)