crumble
Joined: Sep 09, 2008
Posts: 3158
Guildford England
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Posted on Jan 25 2015 09:27 AM
Hi Bjorn. I have a question of which I've wanted to ask for ages.
I have wanted to build a 6G15 clone since about 2009, although my electronic skills are poor I've listened and read other peoples opinions.
Every so often someone will describe the 6G15 as like a tube amplifier, some say it is similar to a Fender Champ in some respects and also you have also described the Surf Bear as class A.
Would a FET Champ Amp it be possible in a format as simple as the Surfy Bear? Or perhaps a low wattage version.
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ludobag
Joined: Jun 05, 2010
Posts: 620
at south of
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Posted on Jan 25 2015 09:44 AM
i answer instead of Bjorn but yes it is possible ,it was already done on fews diy sites
but in the surfy bear the fet attack a low fi componement (the tank) then don't need full spectrum of an amp
one thing to remind is a amp with tube is the sound of the crunchy tube ,even the fets are close they not react the same ways with gain
an amp is 3 things
a preamp
an amp
and a speaker who interact with
since you want something really clean it works
but the saturation of tubes is not easy to simulate
there s a lot of project i know where the guys simulate the response of amp with fet (i know a project with the preamp of twin ,marshall and vox combined you can select )but it stay for clean
after if you want to simulate the saturation of a tipical amp it is doable (look at calindbread box ,vox ,ampeg ,hiwatt ect...)
but to do an amp with clean of the amp and the dirty side it need some big analyse of the circuit and maybe it will doesn't sound like the real one
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crumble
Joined: Sep 09, 2008
Posts: 3158
Guildford England
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Posted on Jan 25 2015 10:34 AM
Thanks for your response Ludo, "not as easy as that" will satisfy my curiosity for now..
I have a reason for asking but this will go off topic I'm sure. I'll look to these DIY sites. cheers.
Last edited: Jan 25, 2015 10:35:25
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Gilette
Joined: May 04, 2014
Posts: 734
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Posted on Jan 25 2015 10:55 AM
Step one.
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bjoish
Joined: Jul 06, 2010
Posts: 596
Stockholm
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Posted on Jan 25 2015 03:33 PM
crumble wrote:
Hi Bjorn. I have a question of which I've wanted to ask for ages.
I have wanted to build a 6G15 clone since about 2009, although my electronic skills are poor I've listened and read other peoples opinions.
Every so often someone will describe the 6G15 as like a tube amplifier, some say it is similar to a Fender Champ in some respects and also you have also described the Surf Bear as class A.
Would a FET Champ Amp it be possible in a format as simple as the Surfy Bear? Or perhaps a low wattage version.
Interesting question 
Of course it would be possible but, as Ludos says, its difficult to simulate the nonlinear behaviour of an overdriven tube amp.
Clean sounds would sound great. To simulate the sound of a heavy overdriven tube amp is a real challenge.
The FET Reverb power amp is different to most solid state amps since there is no negative feedback and the output impedance is quite high. Just like many tube amps.
I have plans to do some serious experiments but its hard to find the time 
You can try to connect a 8 ohm speaker to the Reverb-out RCA connector of the FET reverb. If you got a good speaker/cabinet it should sound ok.
Today I tested a R4 board connected to a cab with a 12" Celestion G12H.
For use at home, I think the sound was very good.
Possibly, the harsh sound when overdriven can be fixed by adding an inductor (same as used as crossover filters in Hi-Fi speakers) in series with the speaker. 0.3 - 0.4mH would roll frequencies above 4000Hz.
No rocket science but interesting stuff isn't it?
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bjoish
Joined: Jul 06, 2010
Posts: 596
Stockholm
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Posted on Jan 25 2015 03:36 PM
Gilette wrote:
Step one.
Looks good, those screw terminals are neat!
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crumble
Joined: Sep 09, 2008
Posts: 3158
Guildford England
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Posted on Jan 25 2015 07:45 PM
No rocket science but interesting stuff isn't it?
Absolutely it is! 
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Gilette
Joined: May 04, 2014
Posts: 734
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Posted on Jan 26 2015 01:28 AM
bjoish wrote:
Gilette wrote:
Step one.
Looks good, those screw terminals are neat!
Thanks, easier to swap in case you come up with yet a better version. 
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Gilette
Joined: May 04, 2014
Posts: 734
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Posted on Jan 26 2015 01:28 AM
bjoish wrote:
Gilette wrote:
Step one.
Looks good, those screw terminals are neat!
Thanks, easier to swap in case you come up with yet a better version.
I really don't know why I posted this twice...
must have been playing surf on the send button...
Last edited: Jan 26, 2015 08:49:36
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hamerman55
Joined: Jan 18, 2015
Posts: 13
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Posted on Jan 26 2015 11:43 AM
I'm waiting on my kit and toolbox to come in, and was thinking about reverb tanks. I can't really pick up a consensus. It seems like there are not a lot of "C" tanks out there. Amazon has the Accutronics or MOD 4AB3C1C, shipped from Amplified Parts. After reading their great article on reverb tanks, it seems that vertical mount is better, and is what is used in the actual Fender tank. Is this correct? I figure I can use Stratdancer's spring mount in the side of the toolbox, and balance the weight with the power supply.
It might be useful to have a poll of good reverb tanks. Can we do that?
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Gilette
Joined: May 04, 2014
Posts: 734
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Posted on Jan 26 2015 12:10 PM
You're right Hamerman, I've noticed the same thing. That's why I'm going for a horizontal mounted tank at the bottom of the cabinet. With a normal 4AB3C1B. Perhaps I'll use a tank bag or springs on studs to isolate it.
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bjoish
Joined: Jul 06, 2010
Posts: 596
Stockholm
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Posted on Jan 26 2015 12:15 PM
hamerman55 wrote:
I'm waiting on my kit and toolbox to come in, and was thinking about reverb tanks. I can't really pick up a consensus. It seems like there are not a lot of "C" tanks out there. Amazon has the Accutronics or MOD 4AB3C1C, shipped from Amplified Parts. After reading their great article on reverb tanks, it seems that vertical mount is better, and is what is used in the actual Fender tank. Is this correct? I figure I can use Stratdancer's spring mount in the side of the toolbox, and balance the weight with the power supply.
It might be useful to have a poll of good reverb tanks. Can we do that?
Hi hamerman55
Try to search this website!
There is lot of info about all kinds of reverb pans.
Unfortunately, the sound can differ a lot between two identical units.
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hamerman55
Joined: Jan 18, 2015
Posts: 13
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Posted on Jan 26 2015 01:16 PM
Thanks bjoish:
I did a little at your recommendation, and clearly this is a question without a good answer. It looks like it would be wise to configure the Surfy Bear case to make it easy to switch out pans, or even put two different ones in the case. I think that is what Stratdancer is looking into.
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warioblast
Joined: Nov 23, 2014
Posts: 98
Dijon
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Posted on Jan 28 2015 08:02 AM
I'm going to need your help guys. I've just finished soldering my V.4 reverb and I'm having some problems. I have a low volume and quite some distortion but not much reverb. Though when I shake the tank I can hear it bubbling. The controls seem to work fine. I'm using a stabilised 12VDC 1000mA power supply. I did check the polarity at the DC jack. 
Last edited: Jan 28, 2015 08:03:34
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crumble
Joined: Sep 09, 2008
Posts: 3158
Guildford England
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Posted on Jan 28 2015 08:35 AM
Check your RCA cables are the right way around.
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SanchoPansen
Joined: Jan 04, 2011
Posts: 1588
Berlin L-Berg
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Posted on Jan 28 2015 08:44 AM
Yes, sounds like the RCA cables are connected the wrong way.
— The Hicadoolas
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warioblast
Joined: Nov 23, 2014
Posts: 98
Dijon
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Posted on Jan 28 2015 09:15 AM
^^ THANKS GUYS for the quick reply. That was an easy fix. 
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12AT7
Joined: Oct 15, 2011
Posts: 1
Oslo
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Posted on Jan 29 2015 02:57 AM
Hi
Long time lurker and first poster here. I have been following this thread for quite a while now and finally ordered it after asking a few questions. Got it shipped very fast and built it last week with excellent support from Björn.
After a few hiccups like managing to short one of the FETs to the chassi I have it up and running with a TAD 4AB3C1B pan. I don't have the words to express how much I love this thing. Playing my american special strat with this on 646 into my beefed up Weber 5E3 kit (bigger PT, 25V extra B+, TAD 6V6GT-STR power tubes, Jensen reissue C12Q) is sonic bliss. I think it'd be even more awesome with a blackface dekuxe but for now I have the "clean" tweed sound in a small package. I just need to learn how to play
Thanks again bjoish for a truly amazing piece of kit. I can not thank you enough. Ever. 
/Helge
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Badger
Joined: Nov 16, 2013
Posts: 4536
Wisconsin
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Posted on Jan 29 2015 06:16 AM
Glad to hear you like it Helge. I don't need one of these at all, but would like to build one "just becasue" - awaiting some Springtime junk/yard sales for inspiration to find the just the right outrageous thing to use as an enclosure.
— Wes
SoCal ex-pat with a snow shovel
DISCLAIMER: The above is opinion/suggestion only & should not be used for mission planning/navigation, tweaking of instruments, beverage selection, or wardrobe choices.
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warioblast
Joined: Nov 23, 2014
Posts: 98
Dijon
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Posted on Jan 29 2015 02:46 PM
I'm experiencing a little hum. I once more read the thread from page 1 and before I start messing with RCA plugs / cables, can I safely try using a 14V 450mA power supply or is it too much ?
My chassis will be mounted backwards; the open side facing the front of the cab; so I won't be able to try Björn aluminium foil trick.
Tomorrow is clear coat day, so expect some pics of my finished build on Saturday.
Last edited: Jan 29, 2015 14:47:31
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