Two Stroke Amp by Dave Hunter

[Boogie92801]

So,

There was a thread about his book but has anyone here built the amp he describes in the book?

[boobtoob]

Yes, it was my first build. I learned alot to say the least. And now I am "possessed" by the DIY bug. What other thread discussed the "Two Stroke"?

Regards,
Boobie

[Boogie92801]

Well they discussed the book more than the amp but I am interested in that project.

How did it turn out? Is it a usable combo? I have plenty of usable amps for my gigs but a small combo to learn on and to jam at the house interests me. I have a couple of friends that are seasoned amp builders and I have access to their help if needed.

I was originally considering a Weber 5F2A or 5E3 kits but the two stroke looks interesting.

Can you describe it's tone? Can it get a decent clean at all? Was it difficult to build the first time?

How does it's volume compare to say a Princeton or a Deluxe?

[boobtoob]

The "Two Stroke" is probably, from what my novice building experience tells me, a 5F2A circuit...but hotrodded. (bigger PT and OT)

It is the first Class A amp I have used, so I can't faithfully compare it to others I use. I also built Mission Amp's 5E3...the two sound similiar to my ears...you know...the tweed sound...kinda dirty, but kinda clean. It's not as clean as my 100 watt Twin, but I didn't/don't expect it to be. Being mostly a country player, I like the way the "Two Stroke" adds just a little bit of overdrive and can still twang with a tele plugged in. IT IS LOUD ENOUGH for a gigging country band, for sure.

I would include some sound clips, but I'm not sure how to do it on this board. It was a fun build, easy instructions, and Dave replied to may emails quickly and friendly.

I did increase the first power cap and add a choke to quiet it down, but other than that, it is a keeper. I used the higher voltage tap, I think it is 330.0.330. The dual 6V6's have close to 400 on the plates, but they haven't shown any un-natural red glow...yet. With the 300.0.300 tap, I got about 325 on the plates, with less headroom. I'm thinking of putting in a dpdt toggle switch to have both taps easily available.

[Boogie92801]

Sweet! That sound like it would be fun and practicle too. Did you make the 1x10,1x8 or a 1x12?

I was thinking of a 2x10 or 1x12 and I would do the cab myself. Oh, did you get the kit or did you source the parts?

[boobtoob]

I order the complete kit, cab and 12" celestion, but now I kinda wish I would have just ordered the chassis only. Not that the celestion is bad (it rocks big time), but I like the idea of having all my amps interchange-able with different speaker cabs. I have an old gutted Fender Twin cab with 2 12" eminence speakers...made it into a closed back cab by glueing (sp?) a big piece of plywood over the open back. It makes for a great speaker setup that is interchange-able with other amp heads. The "Two Stoke" pushes more air with the 2 12" setup, IMO.

The only parts I sourced myself were:

60uF filter cap Antique Electonics
choke from Ted Weber
22 gauge solid core hookup wire (easier to work with than stranded, IMO)
SPST toggle switch (to switch the NFB in/out)

I had to buy an expensive Unibit for my drill press as the chasis Dave sent me had changed from parralleled output tubes to single output setup. I am not sure why he changed that particular feature. Maybe he couldn't find the hotrodded chassis punched with the necessary holes. I like the option of 2 6V6's parrallel, so I drilled the extra chassis hole, and he sent me and extra 8 pin socket, no charge.

Good luck with the project, if you get stumped, feel free to ask any questions. I visit this board and many others when things get slow at work.

Regards,
Boobtoober

[Oatman]

Just finished studying Dave Hunter's book. Have a million questions!

I'm starting to slowly acquire the parts for the two stroke, as the kits are on hold for a while...

I was thinking of using Mercury magnetics for the tranies. Which one looks right for the Hammond 125ese OT and Webber w022772 125p1b PT?

On that note, I'm rather fuzzy on exactly the differences between an OT and a PT??? One supplies voltages for the tubes, heaters, leds, and the other powers the speaker? Are they essentially the same thing and it's just called an OT when it's at the one end and a PT when it's on the other? Could the PT for one amp be in theory the OT for another?

TIA!!!

[doctord02]

Power transformer and output transformers are not interchangeable; the wiring is different and they are wound to make very specific up or down conversions between high and low voltages (and vice-versa). Output transformers also come in different functional designs, single-ended (one tube, or parallel wired tubes) and push-pull (two or more wired in opposing pairs). Again, different wiring, and different applications.

[epluribus]

Do a bit of digging around builder websites for transformer opinions. Heyboers get some pretty good press, (As do MMs, to be fair.) but you don't pay nearly as much as you do for what seems to be the MM brand name. Some builders even like the Heyboers better. Kinda looks like there's some clever marketing even in the transformer biz.

--Ray

Just finished studying Dave Hunter's book. Have a million questions!

I'm starting to slowly acquire the parts for the two stroke, as the kits are on hold for a while...

I was thinking of using Mercury magnetics for the tranies. Which one looks right for the Hammond 125ese OT and Webber w022772 125p1b PT?

On that note, I'm rather fuzzy on exactly the differences between an OT and a PT??? One supplies voltages for the tubes, heaters, leds, and the other powers the speaker? Are they essentially the same thing and it's just called an OT when it's at the one end and a PT when it's on the other? Could the PT for one amp be in theory the OT for another?

TIA!!!

[jlummaa]

I made my Two Stroke about two years ago. It was a nice little project where i learned a lot. My first one. I didn't buy the kit so i bought my parts from different places. I just used more powerful OT and PT, and a different speaker.

Here's some writing, pics, and clips i did at the time:

http://www2.uiah.fi/~jlummaa/two_stroke/

[guitarsnguns04]

cool page Janne. How much $ did you have in that project?..if you dont mind me asking.

[jlummaa]

cool page Janne. How much $ did you have in that project?..if you dont mind me asking.

Thanks!

I haven't calculated exactly but my estimation is 700-800 € ;)

[Seakayak]

I'm going through Dave Hunters book with intentions of eventually building the Two Stroke, (my first build!), but I would like to add a reverb tank to the circuit. If anyone has ideas on how to do this... much appreciated!

[stratman_el84]

On the subject of transformers and chokes, John at Dixie Soundworks is great. He's very knowledgeable, and can usually point you in the right direction if you have tech questions. He has a wide range of stock models, and can custom wind vintage-type-construction and special-order transformers and chokes to spec also. Prices are reasonable, and service/shipping is quick. I've had great satisfaction in all my dealings with Dixie Soundworks over the years.

DIXIE SOUND WORKS.--382A Gunter Avenue, Guntersville, Alabama 35976. Telephone: (256) 582-2425. Fax: (256) 582-6681. Email: jeg.dixie@mindspring.com. Contact: John Gurley.

Good luck!
Cheers!

Strat

[Nolatone Ampworks]

The "Two Stroke" is probably, from what my novice building experience tells me, a 5F2A circuit...but hotrodded. (bigger PT and OT)

It is the first Class A amp I have used, so I can't faithfully compare it to others I use. I also built Mission Amp's 5E3...the two sound similiar to my ears...you know...the tweed sound...kinda dirty, but kinda clean. It's not as clean as my 100 watt Twin, but I didn't/don't expect it to be. Being mostly a country player, I like the way the "Two Stroke" adds just a little bit of overdrive and can still twang with a tele plugged in. IT IS LOUD ENOUGH for a gigging country band, for sure.

I would include some sound clips, but I'm not sure how to do it on this board. It was a fun build, easy instructions, and Dave replied to may emails quickly and friendly.

I did increase the first power cap and add a choke to quiet it down, but other than that, it is a keeper. I used the higher voltage tap, I think it is 330.0.330. The dual 6V6's have close to 400 on the plates, but they haven't shown any un-natural red glow...yet. With the 300.0.300 tap, I got about 325 on the plates, with less headroom. I'm thinking of putting in a dpdt toggle switch to have both taps easily available.

On your Mission 5E3, do you find it to be very compressed and saggy when you crank it?

That's pretty much the description of a cranked 5E3 I suppose, but I've been plagued by having my Greer Underdog 15 Mod 1 to compare it to, and that little amp just chews a stock 5E3 out and spits it out. It's got more headroom before power supply sag, but don't mistake that for "clean headroom". It's crunching at 2 on the dial. I didn't realize the difference until I played it next to my stock 5E3 through the same cab.

Nick uses beefier transformers and a slightly higher gain preamp and a few other tweaks that make the "Mod 1".

I can't leave mine well enough alone. I'm experiementing with transformers and stuck a master volume in there. Also experimenting with coupling caps, cathode bypass caps, load resistors on the preamp tubes, and hacked out the normal channel and am going to play with some cascading of gain stages. Also, tone stack stuff too!

When I'm done, I don't think I'll be able to use Tweed OR Deluxe in the name :-)

[Seakayak]

Found these links...

http://www.myspace.com/twostrokeampkits

http://my2strokeamp.blogspot.com/

[SoCalSteve]

The latest news is that a new kit from Victoria will be coming out.

[Chrome Dinette]

The Hunter book amp has a lot in common with the amp on the Angel Electronics how-to section:
http://www.angela.com/catalog/how-to/super.se.schematic.2.gif

[Curly]

I have the book and sourced parts for the amp build, started then put it aside a while back.

I've been keeping my eye on Dave's myspace, since it looks like the Victoria kit will be available soon.

IMO, this would be a good first build for those who are looking at doing a DIY amp.

The circuit is based on a tweed Princeton, but tweaked, and with the book you have some pretty good documentation (except for a few errors).

I'd expect that with Dave and Victoria collaborating, the new kit should be great.

the only other caveat I have is that potential builders should understand the amp they're building BEFORE putting in the time and effort, so that the end product suits they're needs.

[Groovey Records]

I just ordered the book and expect to start a build this summer. I was hoping to find a Harvard/Deluxe hybrid type tweed kit.

Most importantly I would like to find a good DIY community that I could turn to for questions. Other people who have experience with the same kit I am trying to build. Any suggestions?

GrooVey Records
EnJoY ThE MuSiC

[Rockinrob86]

any word on the price of this from victoria?

[Groovey Records]

Last I heard from Dave was it is being moved back to September. Straight from the horses mouth(email). Keep in touch with him on his my space
http://www.myspace.com/twostrokeampkits

I didn't want to wait and was going to source everything from the book but thought I needed a kit with support for a first build.

The new Two Strokes will have some changes, simplifications and streamlining. IE it will be a single triode SET class A amp unlike the book which is a dual triode SET class A design.

I hope I will get to the Two Stroke as a second build. After reading the book he seems to apply some techniques that other kits don't mention.

I have just ordered an Allan Accomplice which is a higher powered BF Deluxe Reverb AB type amp.

Dave Allan provides email support, step by step detailed instruction with color coded schematics and diagrams. And if you lose it and can't figure it out an hour of bench time to trouble shoot or just critique you work.

http://www.allenamps.com/index.php

Wish me Luck

EnJoY ThE MuSiC
GrooVey RecOrds

[vibroverbus]

The new Two Strokes will have some changes, simplifications and streamlining. IE it will be a single triode SET class A amp unlike the book which is a dual triode SET class A design.


Funny that he's abandoned the parallel output tubes that would have given the "Two Stroke" name in the first place... I understand the simpler-build logic, but kind of weird to keep the name - it's more of the "One Stroke" now... I always did want to play around with a parallel SE design just for the heck of it, still on my long 'someday' project list.

[Laird_Williams]

Yes, it was my first build. I learned alot to say the least. And now I am "possessed" by the DIY bug. What other thread discussed the "Two Stroke"?

Regards,
Boobie
Me too.

The book needs updating. Some of the on-line resources are very helpful.
We ended up needing a big choke to cut down the AC flutter on the high voltage DC. That, the book did not include - but on-line resources did. I'll pull out our notes sometime and pass them on. In the end, it sounded great.

After that, I had the bug. We tried adding another gain stage to it to fatten up the harmonics. We learned a lot about how NOT to do things from this. It was, oddly enough, a great experience.

My buddy and I are doing our own designs now (mostly derivative stuff - but what about tube circuits ISN'T derivative at this point), but I highly recommend building the Two Stroke as a starter project.

Oh yeah - my amp buddy is an RF tech at Ericsson. He also restores antique radios. We built the 2-stroke almost entirely from old radio parts. Even the tubes were hamfest material. The PT was hamfest material. The jacks, pots, circuit card, lamp, sockets, wire, and enclosure were all hamfest material. We bought new PAINT and an inexpensive (but well-made) OT - and that was it for "new". Hamfests are a great way to get used parts for tube amp projects. And the radio guys don't know how much their gear us worth in the "guitar" market. You can get hands-full of vintage tubes for diddly. For $15 or $20 you can get an old radio and dissect it for its working parts worth hundreds in the "guitar" market.

[vibroverbus]

MHamfests are a great way to get used parts for tube amp projects. And the radio guys don't know how much their gear us worth in the "guitar" market. You can get hands-full of vintage tubes for diddly. For $15 or $20 you can get an old radio and dissect it for its working parts worth hundreds in the "guitar" market.

DUDE! ix-nay with the amfest-hay ecrets-say! you're gonna blow it for all of us!

;)

[sixstringer]

I've just finished with a 2 stroke amp, it sounds good and works fine but I have only one issue, the power tube grid voltage is 341 vdc w/ a KT66 (335 vdc w/ at 6L6) using a NOS RCA 5Y3. The Plate voltages are on the high side but within the published limits. Should I try get the grid voltage down to 300 volts? Thanks for your advice.

[Groovey Records]

Welcome to TGP SIXSTRINGER

I would ask whick KT66 you'e using and how does it sound?

Did You do the Two Stroke in the book and did you get the published mods from the myspace site?

Dave will probably return your email through myspace

EnJoY ThE MuSiC

GrooVey Records

[sixstringer]

I built the one tube version and incooporated updated building instructions. I'm using a Value Art KT-66 or a Groove Tube 6L6, the KT-66 is a touch hotter. With the KT-66 and a NOS RCA 5Y3, I get 357 VDC on the plate, 341 VDC on the Grid (G2). With a new Slovtek 5Y3, I'm getting 387 VDC on the plate! I am a noob at tube amp building and am wondering if using the 125 volt connection on the PT would work better, of if using red/white pair from the secondary side of the PT (600v) instead of the red pair (660v) would bring the plate and grid voltage down a bit. Or is there a resistor value that needs to be tweaked? 2 things I've searched for but not found are 1: a schematic for this design, 2: a comparison between the Jensen speakers and the now recommended Weber's. Any help or direction you can offer is most appreciated. I have some photos I would like to share, can I post them here? Thanks

[Groovey Records]

I built the one tube version and incooporated updated building instructions. I'm using a Value Art KT-66 or a Groove Tube 6L6, the KT-66 is a touch hotter. With the KT-66 and a NOS RCA 5Y3, I get 357 VDC on the plate, 341 VDC on the Grid (G2). With a new Slovtek 5Y3, I'm getting 387 VDC on the plate! I am a noob at tube amp building and am wondering if using the 125 volt connection on the PT would work better, of if using red/white pair from the secondary side of the PT (600v) instead of the red pair (660v) would bring the plate and grid voltage down a bit. Or is there a resistor value that needs to be tweaked? 2 things I've searched for but not found are 1: a schematic for this design, 2: a comparison between the Jensen speakers and the now recommended Weber's. Any help or direction you can offer is most appreciated. I have some photos I would like to share, can I post them here? Thanks


best way to post photos is a third party like www.photobucket.com

thats about the only help I can offer except try getting in touch with Dave on my space, he has a shop in New Hampshire.

http://www.myspace.com/twostrokeampkits

EnJoY ThE MuSiC
GrooVey Records

[vibroverbus]

would bring the plate and grid voltage down a bit. Or is there a resistor value that needs to be tweaked? 2 things I've searched for but not found are 1: a schematic for this design, 2: a comparison between the Jensen speakers and the now recommended Weber's. Any help or direction you can offer is most appreciated. I have some photos I would like to share, can I post them here? Thanks

stringer - minor terminology tip - G2 is a proper designation but in conversation is generally called the 'screen' (aka 'screen grid'), when you say 'grid' people would assume you mean G1=control grid. the voltages you're talking about should be fine for plate and screen with such tubes (I have a house full of amps putting 400V+ on the screen/plates of 6L6 type tubes), so I wouldn't worry about it. i think you're in good shape. switching to the 600V taps might be an interesting option to try just for yucks on the other hand, as long as the PT is designed for that (I haven't looked up what PT this is...)

re the other 2 questions - good question on the schematic - he says he never did a schematic for it... seems odd nobody else has done one since even a hacker bone-head like me can whip out an amp schematic in a few hours, and if you're doing a kit for noobs, one of the first things people need practice with is understanding schematics... so i bet SOMEBODY has made one but in at least the quotes I saw, he hasn't...

there are lots of jensen/weber comparisons around in general, so if you don't find one specific to this kit, you you should be able to find an applicable 'generic' speaker comparison. check out tonequest - they have done a number of speaker comparison/shootout type things....

[Groovey Records]

From what is NOW on the Two Stroke Myspace page the new kit is available

http://www.myspace.com/twostrokeampkits

[sixstringer]

Thanks for the great replys. I've created an album on Photobucket with some low rez files, I have more detail shots that I will post soon. This is the link: http://s233.photobucket.com/albums/ee132/SheenDOD/2%20Stroke%20amp/

[Groovey Records]

Hey Sixstringer,

Now that I looked at your Two Stroke I know who it is that I just friended over at MySpace COOL

RED Nice!

[sixstringer]

so it turns out that having the "screen" grid slightly below the plate voltage, as you've all said. A neighbor friend just stopped by and confirmed that my voltage are good, he also brought me a shoebox full of brand new 12AX7's and 6L6s all dated 1959. Sylvania 6L6GC and RCA, pretty cool, huh?

[Seakayak]

Thanks for the great replys. I've created an album on Photobucket with some low rez files, I have more detail shots that I will post soon. This is the link: http://s233.photobucket.com/albums/ee132/SheenDOD/2%20Stroke%20amp/

Nice work! I'm anxious to build one of these.

[stuntdouble]

Does anyone know the approximate cost of sourcing all the parts for the 2 stroke? I just saw that Victoria is selling the kit for $1000, and am trying to decide whether to source parts myself or buy the kit. Since i haven't built an amp before, a kit sounds nice, but if i can save significant $$ purhcasing parts myself I'd do it. Any advice would be great.

thanks.

[RomanS]

1000 $ for a kit for such a small amp seems EXTREMELY high, even if it comes from Victoria; try sourcing the parts from Weber www.webervst.com (the original kit was also supplied by Weber) - should cost half as much at most...

[vibroverbus]

if you've never done an amp before, buying a kit with everything is a really good idea.

that said, this is pretty pricey, but is obviously purely because of the high quality detailed finished cabinet and powder-coated chassis. top notch looking job they've done on them, but still is darned expensive.

I'd suggest going for a cheaper all-in-the-box kit for your first amp... then with some experience you can decide if you want to pay for this or pull the parts together yourself. the few expensive parts in an amp are in no particular order tubes, trannies, cabinet, chassis, and speakers. everything else is pocket change...

[sixstringer]

I built a 5E3 amp with parts sourced mostly from Weber and Antique Electronics. I bought the Mercury transformers from an E-store on Ebay, he had the best prices for Mercury + the best prices for Eminence speakers. I did not purchase a kit because I figured that sourcing the parts is a big part of building the amp and I wanted to learn that. The amp came out great, looks good, sounds good, no problems. Next, I've built the 2 Stroke design, again sourcing all the parts most from Antique Electronics and Weber. I built the cabinet and turret board from scratch and that worked out fine. I'm guessing I have less than $400.00 (maybe alot less) in the project including a chassis from Weber and 2 Jensen speakers (which sound great if you do the C10Q break in trick). Photos of my 2 stroke are posted here: http://tubeampnetwork.ning.com/ I've learned more by doing more myself. Laying out the turret board (which is somewhat different than DH's design) and modding the chassis really had me thinking about lead dress and correct ground connections (my amp is really quiet too, no buzz or hiss). "The Guitar Amp Handbook" by Dave Hunter (with the 2 Stroke amp instructions), "The Tube Amp Book", by Aspen Pittman and all of Gerald Weber's books: "Desktop reference of hip Vintage Guitar Amps", and "Tube Guitar Amplifier Essentials" are all full of info helpful in building amps. If I had to pick just one book to start with, I'd go with "The Guitar Amp Handbook". Good luck!

[Brad737]

I certainly think that's a great looking kit. But there's NO WAY I would EVER consider paying that much for a Fender 112 kit. I can only imagine that they honestly don't want to sell that many of them. Either that, or they're just price gougin. Let's be honest, you can get a Metro Plexi kit for that price. And those kits come with absolutely top-notch instructions on DVD, with absolutely top-level components, and sound superb.

[Braxtone]

Hey folks. A noob here and to amp building. Just finished Dave Hunters book and I want to build this amp. I am in the process of locating all of the parts and am having a hard time locating an axial capacitor; 47uF 400v to be exact. Any recommendations on where to find one? I'm parsing all of the parts on my own because a grand is too much for a DIY amp. Also, any amp building wisdom or suggestions feel free to chime in. It's great to be here.

[banjoze]

this what you are looking for?:

http://www.mouser.com/Search/ProductDetail.aspx?qs=f6ouvUIyX3Czx99VZKZHUw%3d%3d

Hey folks. A noob here and to amp building. Just finished Dave Hunters book and I want to build this amp. I am in the process of locating all of the parts and am having a hard time locating an axial capacitor; 47uF 400v to be exact. Any recommendations on where to find one? I'm parsing all of the parts on my own because a grand is too much for a DIY amp. Also, any amp building wisdom or suggestions feel free to chime in. It's great to be here.

[Braxtone]

Maybe. The listing in Dave's book lists a 47uF 400v instead of .047. I don't even know what an axial capacitor is. Could someone please explain. Thanks for the link banjoze.

[skipm45]

47uF 400v to be exact.

http://www.tubedepot.com/cp-ft-47-500v.html

These guys are ok, I've used them a good bit.


Skip
www.skipzcircuits.com (http://www.skipzcircuits.com)

[skipm45]

axial lead parts have one lead on each end of the can

radial lead parts have both leads on one end


HTH

Skip
www.skipzcircuits.com (http://www.skipzcircuits.com)

[Braxtone]

Skipm45! Thanks broseph! One question, because I am ignorant; Can I use the capacitor with a 500v rating? Maybe you could explain why so that I can understand.

[skipm45]

Yes, the 500v rated cap will be fine. It's always OK tu use a cap with a higher voltage rating. If the voltage rating is too low the capacitor can fail from being overvoltaged.

Skip
www.skipzcircuits.com (http://www.skipzcircuits.com)

[Braxtone]

Ahh! Now I see. Thanks so much for the help. I will definitely be back on here soon asking stupid questions.

[Curly]

Maybe. The listing in Dave's book lists a 47uF 400v instead of .047. I don't even know what an axial capacitor is. Could someone please explain. Thanks for the link banjoze.
read his amp notes here (http://homepage.mac.com/mystro2b/.Public/AmpKitNotesWeber.rtf)

[Braxtone]

Curly, thanks for that link. It is a huge help.

[RomanS]

Weber http://www.tedweber.com/ might also have that part - while he doesn't sell the complete kit any longer, the bill of materials for the Two Stroke is still on his site: https://taweber.powweb.com/store/kits.htm

[TweeDLX]

For what it's worth, Matt at Musical Power Supplies has some decent iron at terrific prices, if you don't want to spring the big cash for a Mercury or Heyboer.
http://www.musicalpowersupplies.com/index.html

Braxtone: You can also use a capacitor that's close in value (say, using a 20uF instead of a 16uf).

Mike

[taylerdo]

Laird,

Please let me know the specifics on your experience with this amp and the implementation of adding a choke, Re: "We ended up needing a big choke to cut down the AC flutter on the high voltage DC" i.e. what size choke, how it was placed in the circuit, etc.

Re: your post on 04-21-2008, 09:15 AM.

I am going to build such an animal, and bought the parts from AES (www.tubesandmore.com (http://www.tubesandmore.com)) last night.

Also, can I send a copy of my AES invoice to you and get your comments on the parts I ordered? I had Dave Hunter 's book in front of me for building the two stroke amp, and did my best. The obvious part I did not figure out is the circuit board to connect the parts to (DOH) so that is TBD. I believe I got the rest, but just guessing as stated above. For instance, I am not sure if the tube bases I ordered are even correct (more DOH). But I will get there eventually ...

Thanks for listening and TIA for your help.

DON

[Braxtone]

Does anyone on here have an updated/revised schematic with the single power tube configuration? If so could you post it?

[skipm45]

Here's a marked up 5F2 schematic with the latest changes from Dave Hunter.

http://i246.photobucket.com/albums/gg106/skipm45/twostrokeschematic.jpg

Let me know if it's hard to read. I'll email it to you.


HTH

Skip
www.skipzcircuits.com (http://www.skipzcircuits.com)