John Mayer/Wonderland build in 17x10in chassis (Audio Clip)

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Guy77
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John Mayer/Wonderland build in 17x10in chassis (Audio Clip)

Post by Guy77 »

20170802_090511_resized.jpg
Hi . I started on a John Mayer/Wonderland build. I got my hands on a 17x10x3in hammond chaassis for $32 and could not resist.
I am using a JTM 45 preamp turrent board for the preamp. I got that for $14 from tubesandmore.com and it works amazing well, I just needed to add a few turrents.
I will be adding one extra switch to the amp and that is for a PAB. I love the way it works on the dumble clones. I will just lift the ground on the Mid pot.

Cheers
Guy
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Last edited by Guy77 on Tue Sep 12, 2017 8:53 pm, edited 1 time in total.
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norburybrook
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Re: John Mayer/Wonderland build in 17x10in chassis

Post by norburybrook »

I see you're doing a 50w. Make sure you use a different value resistor at the 1M/68k voltage divider or you'll have a very quiet amp :D

used a 150k instead of the 68k I think even on my 100w as it cuts so much gain at that point with a 1M/68k


Its a lovely sounding amp.


Marcus
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Guy77
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Re: John Mayer/Wonderland build in 17x10in chassis

Post by Guy77 »

Thank you very much Marcus! I would have been scratching my head for a while figuring out what was wrong!
I will play with some different values there and report back with my findings.

Cheers!

Guy.
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Guy77
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Re: John Mayer/Wonderland build in 17x10in chassis

Post by Guy77 »

Just about finished the amp. Some pics below. Just received my 6L6 JJ tubes and will swap them in. I used to not like JJ tubes but have changed my mind and now like how they sound when running overdrive pedals. Will finish the cabinet this afternoon at my dads little wood working shop in his garage. Changes I made to Taylors layout was to change the 68K resistor to 150k . I also added a 50v B+ dropper with a mosfet that is enabled with a switch on back panel and I also added a switch to disable the NFB on the speaker jack and finally a PAB switch like on the Dumble Overdrive amps. I also added a GZ34 rectifier, not seen in this internal shot but seen on external pic.Should have her powered up tonight! Thank you again Taylor for your layout. I used a hammond 290cx power trans and the output trans was a spare one I had from mojotone from there Trainwreck line.

Cheers
Guy
Inside.jpg
outside.jpg
cabinet.jpg
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telentubes
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Re: John Mayer/Wonderland build in 17x10in chassis

Post by telentubes »

Very nice.
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stelligan
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Re: John Mayer/Wonderland build in 17x10in chassis

Post by stelligan »

Nice looking amp!. Good luck on your power up :)
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Guy77
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Re: John Mayer/Wonderland build in 17x10in chassis

Post by Guy77 »

Powered up the amp last night and it sounds really amazing!!!!!! At first there was no sound and after checking the amp I forgot to solder one of the wires on the Gain pot. :lol: I rolled 3 different sets of tubes in her. JJ 6L6, JJEL34 and TungSol 6v6 reissue. The amp sounds amazing with all 3 types of tubes! Its a 1 channel amp but it is one amazing channel. I like the reverb on this amp more than the typical fender style reverb from a deluxe reverb amp. Also when I dial back the reverb controls I cannot hear any reverb at all, I was worried it would still be there a bit. I changed the 68K resistor that Marcus recommended and the amp really came alive! If I dial up the gain and lower the Master vol I get a really nice overdrive tone as well. This amp has more gain than the clean channel of the 124 dumble clone I built a few years ago and I actually prefer it over the clean channel of my 124 ( but the 124 does have an amazing overdrive channel). I was also impressed on how nice this amp sounds with 6v6 tubes. It makes a great amp for noodling around the house with the 6v6s! I also tried it with my EH USA Big Muff PI Distortion pedal and the overdrive tones are really nice.
I highly recommend this build to everyone! You will not be disappointed !! Thanks again to everyone here for the great input :D

Cheers
Guy
Bombacaototal
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Re: John Mayer/Wonderland build in 17x10in chassis

Post by Bombacaototal »

Very interesting round up summary of your built. Looks fantastic!

Do you mind if I ask what value did you replace the 68k with. As far as the 6V6 did you do any adjustment do the GNFB or wire it to a higher OT tap (ie 16ohms vs 4ohms of the original)
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Guy77
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Re: John Mayer/Wonderland build in 17x10in chassis

Post by Guy77 »

Bombacaototal wrote: Tue Sep 05, 2017 1:52 pm Very interesting round up summary of your built. Looks fantastic!

Do you mind if I ask what value did you replace the 68k with. As far as the 6V6 did you do any adjustment do the GNFB or wire it to a higher OT tap (ie 16ohms vs 4ohms of the original)
Hi. I used a 150k in place of the 68k. I made no adjustment on the GNFB. I used the 12K value that was in Taylors layout in his post. I ended up switching out the 6v6 tubes and running the amp with 6L6 tubes . It sounded a little better with the 6L6s. This might be due to the GNFB resistor value. The OT I used is a 6.6K 35 watt model from a trainwreck build . Big heavy 4.5lb trans. What I did was run my 8ohm G1265 speaker with imp switched to 4k. This would bring the OT done to 3.3K.


Cheers

Guy
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Re: John Mayer/Wonderland build in 17x10in chassis

Post by brewdude »

I was under the impression that running an 8R speaker into the 4R jack would reflect twice the impedence--meaning that your PA would see a 13.2k reflected impedence using a 6.6k primary.

Edit: I now wonder if you are talking about the NFB resistor(?).
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Guy77
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Re: John Mayer/Wonderland build in 17x10in chassis

Post by Guy77 »

brewdude wrote: Wed Sep 06, 2017 1:46 am I was under the impression that running an 8R speaker into the 4R jack would reflect twice the impedence--meaning that your PA would see a 13.2k reflected impedence using a 6.6k primary.

Edit: I now wonder if you are talking about the NFB resistor(?).
Hi. Yes you are correct I should be setting my amp speaker imp switch to 16 in order to half my output trans primary imp. Thanks for the correction!
In regards to which resistor I left as 12K, I have circled it in green on the layout below ( close to were it says NFB on the pre-amp board). Was this the one you were also referring too?
Thanks again!
JMSig.jpg
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norburybrook
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Re: John Mayer/Wonderland build in 17x10in chassis

Post by norburybrook »

putting the local and global negative feedback on switches is something I'd recommend as it's an easy thing to do. The amp with both these OFF is quite raucous :D

with them both ON it's back to the smooth clean sound you'd expect.


Marcus
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Guy77
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Re: John Mayer/Wonderland build in 17x10in chassis (Audio Clip added)

Post by Guy77 »

Got a friend of mine to demo the amp on the weekend. His name is Dave he is a much better player than me lol.
Here is the youtube link to it. Its the black amp. We are in a big 2 car garage here in the suburbs. The cab is filled with 2 x 12 Celestion Golds.
He kicks in the PAB at 1:19 and at 3:23 he really cranks it and lets it rip! Its a sony A7 with its built in mic doing the recording. Running the amp with 2 x 6L6s here.

https://youtu.be/ArNLEGyzuc8



Cheers
Guy
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Re: John Mayer/Wonderland build in 17x10in chassis (Audio Clip)

Post by JazzGuitarGimp »

Nice sounding amp! Nice that he snuck a few bars of Giant Steps in there... you thought I wasn't listening, dint'cha? :-)
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Re: John Mayer/Wonderland build in 17x10in chassis (Audio Clip)

Post by pompeiisneaks »

Sounds really nice! I dig it! Well done.

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