Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: tubenit on September 16, 2021, 12:04:02 pm

Title: 6BM8 amp
Post by: tubenit on September 16, 2021, 12:04:02 pm
If I am remembering correctly,  I can just cut and shrink tube the "screen" wires on the output transformer if I am not wanting to use them?


Correct?


With respect, Tubenit
Title: Re: OT screen wires question
Post by: sluckey on September 16, 2021, 12:08:26 pm
yes
Title: Re: OT screen wires question
Post by: tubenit on September 16, 2021, 01:26:42 pm
Thank you!     With respect, Tubenit
Title: Re: OT screen wires question
Post by: Willabe on September 16, 2021, 02:24:34 pm
What chu doin' now Jeff? :icon_biggrin:
Title: Re: OT screen wires question
Post by: tubenit on September 16, 2021, 08:52:18 pm
Amp for a zero volume stage.  :icon_biggrin:   A 7 watt clean tone amp to be a platform for effects pedals.  It's similar to my "the Minimalist" HoSo56 but V1 is a paralleled 12A_7 instead of a 5879.   Dummy load resistor and a Hughes & Kettner Red Box cabinet emulator into a PA system.  No speaker on stage. 




Cab is made out of 100 yr old pine taken from an old hosiery mill and then has some flamed maple, inlaid logo out of waterfall bubinga, front panel out of flamed anigre,  an inlaid cross out of rosewood, and some sapele trim. All scrap woods left over from various projects.  The Mill was built in 1924 in Belmont, NC.


With respect, Tubenit
Title: Re: OT screen wires question
Post by: glass54 on September 16, 2021, 09:21:30 pm
Absolutely Gorgeous Cabinet TubeNit  :worthy1:
(I'm a little jealous  :laugh:)
Kind Regards
Mirek
Title: Re: OT screen wires question
Post by: Willabe on September 16, 2021, 10:56:24 pm
WOW!   :bravo1:
Title: Re: OT screen wires question
Post by: TIMBO on September 17, 2021, 04:06:06 am
NICE
Title: Re: OT screen wires question
Post by: tubenit on September 17, 2021, 07:56:32 am
Thanks guys!  The old hosiery Mill has been converted into a church although not all of the Mill has been finished out yet. The zero volume amp is for that church band and so it seemed appropriate to the "renovation" being done to make the cab head out of the 100 yr old pine.   :icon_biggrin:   The renovation work has alot of "repurposing" being done which is kinda cool in my book.


My understanding is the Mill was one of the first hosiery mills of it's kind anywhere. 


With respect, Tubenit
Title: Re: OT screen wires question
Post by: tubenit on September 17, 2021, 01:59:16 pm
The amp is finished and sounds excellent to my ears.  Similar to the Minimalist amp I've done.  However using a paralleled V1 12A_7 type allows more versatile gain structure.  I will say this amp is loud for 7 watts!  The PPIMV is useful.


With the PPIMV cranked up and the volume pot at about 7 using a 5751, it's got some pretty nice overdrive and sustain to it.  With PPIMV down to 7  and the volume at about 6, it cleans up very nicely for a clear clean tone.



It's not a neat wiring job but the amp is dead quiet at idle.  Effects loop works quite well.  Very pleased with how this turned out.  Fired right up and no issues.  :icon_biggrin:


With respect, Tubenit
Title: Re: OT screen wires question
Post by: Tone Junkie on September 17, 2021, 11:41:20 pm
Looks awesome Jeff.
Title: Another 6BM8 amp
Post by: tubenit on September 19, 2021, 02:12:32 pm
When I made the amp cab, I left enough room on the back side to have the dummy load resistor and the Red Box "under the roof" so to speak so nothing was protruding out. 


This is how it turned out.  I will use an XLR line in a day or so to record the Red Box cabinet emulator.


With respect, Tubenit
Title: Re: 6BM8 amp
Post by: pullshocks on September 20, 2021, 01:55:34 pm
That's ingenious how you  incorporated the dummy load and red box into the enclosure.  Very cool.
Title: Re: 6BM8 amp
Post by: 72Blazer on September 21, 2021, 06:06:38 am
Amazing craftsmanship.
Title: Red Box cabinet emulator VS. speaker cab
Post by: tubenit on September 21, 2021, 08:54:55 pm
IF you are interested in hearing how well this concept of a dummy load resistor using a Hughes & Kettner Red Box speaker emulator works ....................


Here is a "test" for you to see IF you can tell what is a speaker cab and what is the cabinet emulator !! 


Red Box cabinet emulator VS. speaker (el34world.com) (https://el34world.com/Forum/index.php?topic=27994.new#new)


 :icon_biggrin: :icon_biggrin:


With respect, Tubenit
Title: Re: 6BM8 amp
Post by: Fresh_Start on September 22, 2021, 09:18:24 am
Jeff - it sounds great and the cab is just beautiful. Your tone tweaking and woodworking both just keep getting better.

Cheers
Chip
Title: Re: 6BM8 amp
Post by: tubenit on October 01, 2021, 07:39:41 am
OK,  I had a chance to play this amp thru a nice PA system yesterday!


I thought it sounded excellent!  Zero floor noise. Warm musical tone. FX loop works great and adds no floor noise that I can hear.


The Red Box  cabinet emulator definitely sounded like a cabinet speaker to my ears.  It's a "newer" model and the old model Red Box cabinet emulator I had previously tried had been greatly improved on. 


I don't think anyone hearing the amp thru the PA would know there was no speaker cabinet being used (to maintain a ZERO volume stage)!  It should be noted that the sound clip I posted of "whether it was a speaker or the Red Box"  .............. that NOT a single person guessed it right. In fact, more votes went to the Red Box thinking it was a cab speaker.


The other feature that I liked about the amp is that we tried an acoustic guitar into a delay pedal into the FX return with the PPIMV turned almost all the way up. It really added a rich warmth to the acoustic tone!  I was pleasantly surprised how well this worked.


Just thought I'd update the results thru the PA.    With respect, Tubenit










 
Title: Re: 6BM8 amp
Post by: jojokeo on October 04, 2021, 02:50:34 am
Sounds really nice Jeff!