Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Raoul Duke on December 05, 2024, 09:08:09 pm
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Hi All,
Putting together my BOM to build a Sluckey DL-B and had a couple of questions for those who’ve already built one. With any luck - the man himself might chime in. He has lent me expert advice in some previous builds over at TAG; which I certainly appreciate.
1. Has anyone tried the AC15 “Jump” or channel select mod on this amp? My understanding is that channel select does both - hence the on/on/on switch?
2. The rotary switch cap values look slightly different from the DL to the SEL AC15. Any opinions regarding which set is more effective at giving different tonal variation?
3. Looking to use Heyboer 18w Marshall type iron unless there are other suggestions?
4. On the fence about building it with the MV. Any opinions regarding its’ performance?
5. Any hints or wisdom to impart based on experience with this build.
Spent the past week searching different threads here about the DL and have seen quite a cross section of adaptations of the original circuit - all very helpful and informative. I appreciate any info anyone would be willing to share! Been eyeing this project for a while and I’m excited to get started. I think it’ll be quite a versatile amp for sure.
Many thanks and regards,
Marc
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In case you dont have the link:
http://sluckeyamps.com/index.htm
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Thank you,
I’ve spent a lot of time checking out his various designs and couldn’t decide between the Plexi and the AC - which is what pushed me to “how ‘bout both in one box?” Lol.
The coolest design is that toaster (by far). Repurposing an appliance in such a way is definitely creative.
Thanks again, I appreciate the help!
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Hi I have built a DL just like Sluckeys design and love it the way it is. Is the "jump" mod you speak of using both channels at the same time? Never heard of that and don't know what would happen or how it would sound.
I used an AO-39 PT and the Hammond 1750PA output transformer which is really a nice piece of iron. It is open with no endbells and is all black and sounds excellent. I've used that OT in a couple of builds. https://www.hammfg.com/part/1750PA (https://www.hammfg.com/part/1750PA) I would think the Hammond Marshall 18w PT is probably very good too.
The Dual Lite was built by Steve at a later date than his previous AC15 build so the only thing I can say about the AC15 Lite briallance switch is that he prefered those capacitor values over the previous values he used for some reason. What is a SEL AC15? pardon my ignorance.
Hopefully others who have built a DL will chime in.
I will add the AC15 side is really nice and sees most of the play time with the amp.
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edit: oops. Misread the title and assume you were in the UK. So have removed recommendations for UK suppliers.
Personally I thought about combining the channels but decided not to. As is, the channels are out of phase. You can run them in phase (there's a link on here) but then you have to use mixing resistors and sacrifice some gain which to me defeats the point .
COmbining preamp:
file:///Users/paultrynka/Downloads/Mixing%20the%20Preamp%20on%20the%20Dual%20Lite%20(1).pdf
Here's a link on the 6-way switch I have bookmarked
https://el34world.com/Forum/index.php?topic=23237.0
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Hey thanks guys! Great stuff!
mresistor,
SEL AC15 is Steve’s AC15 build. The info about the switch is definitely helpful and another builder favoring the AC15 side. I appreciate the x-former info as well, thanks!
G-Paul,
Great info about the trade off for blending channels. Very helpful, thanks! Tried the blend link but couldn’t get it to work. Can you check it and repost if needed please? Very much appreciated!
Exactly the kind of advice I was hoping for.👍
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Found the thread on combining the input channels using 220k mixing resistors. This has the PDF which I couldn't seem to attach.
https://el34world.com/Forum/index.php?topic=18330.0
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Thanks again Paul!
I think I read every thread there’s been on these, but I’m still digging.
Pretty well decided that I’m going to build it as designed by Steve and play/evaluate to decide if I want anything else. Everyone who’s built one has sold me on the simplicity being a big part of the sound. Makes sense to me.
Expecting a Mouser box any day now…
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Here’s the channel blending revision from the man himself:
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I built this one last year and is a very good sounding amp, I used his master volume mod and it's great for home use.
I'm a beginner so aren't 'up' on the switching mentioned but wired as is there is some interaction between the 2 channel volume pots and my Marshal side is quieter when turned up.
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I built this amp, the 12ax7 side never gets used....I also got channel bleed, couldn't solve it..Might be because I used a dual can cap..
Type2 MV works as schematic...I used 500k
EF86 - I shot for 130v Plate, 90v Screen
The amps not the best sounding tbh...You'd be better off doing away with the 12ax7 side and using that space going into CF tone stack..
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The amps not the best sounding tbh...You'd be better off doing away with the 12ax7 side and using that space going into CF tone stack..
What's the issue? Both channels are well-proven designs, much-loved especially at the 18Watt forum. Obviously there might be significant variations due to transformer, speaker choice etc. But this is as classic a circuit as you could ask for.
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Well if a single 12Ax7 into a PI with a tone knobs your thing go for it...
The moneys in the Ef86 side, but your lacking gain stages to get any juice...Decent pedal platform like
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All very interesting and I appreciate everyone’s different perspectives.
My plan is to build it as specified in “Rev 1” and then see where I’m at after playing it for awhile.
My first 3 builds were Dumble ODS recipes; which turned out fantastic and I really enjoy. Built a Tweedle Dee about a month or two ago and it got me thinking that the simpler circuits really have a lot to offer. The Dual Lite seems like a great complement to the Tweedle. Definitely have high hopes for this design.
Thanks again all!
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Hey Raoul,
I've built two of Sluckey's dual-preamp designs, including the Dual Lite British that you're planning on building. I love the EF86/AC15 side of the amp (it gets deliciously crunchy). To me the Marshall 18 is less interesting in comparison. (I also built Sluckey's Dual Marshall circuit with the power section from his 6V6 Plexi design, and the juicy side of that amp is the JCM800 -- way more fun than the Plexi side.)
There is one thing I would have done differently in the British Dual Lite circuit design. The channel switch is right behind the input jack, and the outputs of the two preamps are combined. This means that you have to turn the volume down on the channel you're not using, in order to get rid of the noise floor hiss and hum of the unused preamp, which can be considerable if you have the volume up. Flipping a switch and adjusting two volume pots is certainly not something you'll be doing very quickly on the fly.
Sluckey's Dual Marshall design (preamp schematic attached) has the channel switch at the back of the preamps, where they would otherwise simply be combined. The input is not switched -- the input jack feeds both preamps all the time, but the channel switch chooses between the two preamp outputs right before the PI. The output from the unused preamp is disconnected, so you're only dealing with the noise floor of one preamp at a time, without having to turn the volume down on the "off" channel. It's a much better design, IMHO. You can keep the volumes of the two preamps set in balance and simply flip the switch.
I'll get around to rewiring the switch on my British Dual Lite someday.
Have fun with your build!
Russ
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Another important point is that it's very common for EF86s to be microphonic. I built my Dual Lite as a combo, but I had to cut it down to a head because none of the EF86s I got were quiet enough to withstand the vibration. I don't even put the head on the same speaker cab I'm using.
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Hey Raoul,
I've built two of Sluckey's dual-preamp designs, including the Dual Lite British that you're planning on building. I love the EF86/AC15 side of the amp (it gets deliciously crunchy). To me the Marshall 18 is less interesting in comparison.
I've noticed this is becoming a bit of a consensus. Which worries me as I want to build the Dual Lite primarily to replace a 20W Park.
Given the 18W notoriously is gainier/has less headroom than an AC15, why might they be the other way around in the Dual Lite? Thoughts? Theories?
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The EF86 pentode preamp has lots more gain than the 12AX7 parallel triode preamp.
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But would the EF86 have more relative attenuation in the PI or power amp stage to make the overall gain structure so different? Because AC15s are not known for their overdrive, compared to 18W.
I guess the character of 18W is that the overdrive comes from power tubes and OT, so one simply has to accept that having two channels is a kind of a compromise, you're not going to switch from one to the other.