Vibrodriverb special

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bepone
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Vibrodriverb special

Post by bepone »

In making!
Vibrodriverb or vibroverbdrive special, strange name first and second, let be first then. :P

Empty cab i had 6 years waiting for something, collecting the dust..Idea was to make some combo with neodimium speaker, 1x12" or 1x15", Fender style. Vibroverbs are very expensive and i like SRV sound..So vibroverb like guideline.

To make project more complicate, vibrato will be out from standard layout, to be deployed with LND150 and relay to make some better layout and avoid noise ("thump-thump").
Maybe AB2 driver for power tubes with 12BH7, 5678 , 6CG7 or some other powerful dual triodes, i will se what my eyes will see and hand grab first. Also interstage is option too, i have also one waiting for that.
To be added also Dumble overdrive stage and tone stack. :P Will be vibrato and heavy overdrive.

Output transformer, and reverb trafo will be DIY, made for some of tanks what is also only collecting the dust. Power transformer i have from some other project.

Speakers waiting to be used JBL D130F or some modern Neo Jensen. Many parts waiting to be used, time to start some assembly!
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bepone
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Re: Vibrodriverb special

Post by bepone »

i stated with the box, long time ago built by my friend..it was for some bandmaster head to combo conversion. so chassis for standard bandmaster will go.
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chassis also i had, test fit of the tube town chassis , combination of 2 independent positions bought in different time looks like perfect fit, all ok for the project,
129.jpg
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bepone
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Re: Vibrodriverb special

Post by bepone »

drilled holes on the chassis.
some details on the TT chassis i didn't like at all, like corners, looks like some over-engineered corners for nothing! only to create the problem in vibration in combo amp? filled with the metal epoxi and sanded.
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sas2.jpg
sas1.jpg
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bepone
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Re: Vibrodriverb special

Post by bepone »

transformers wound, OPT and reverb driver transformer..varnished. OPT will be subject to change if not ok, so probably i will rotate several candidats for it. vibroverb has very small output transformer like band master, but i dont like dumble drive on this small types, already tested, so i think i will go for oversized version..
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ot i reverb.jpg
i have idea to make original vibroverb OPT in beeswax to be maximum vintage as possible, and did , mixed beeswax with parafine, but results on testing with dumble drive and open back combo were like missing the bass. so small transformer is second option here , or no option at all..will see after.
131.jpg
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bepone
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Re: Vibrodriverb special

Post by bepone »

cabinet tolexing in standard fender black tolex..without metal corners..simplistic. looks like i need to buy some more tolex.
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bepone
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Re: Vibrodriverb special

Post by bepone »

preamp built on pcb which was made for some Dumble amp with Dumblelator. relays for OD and boost are on it. Dumblelator part will be used for vibrato mixing triodes.
material, on the beginning MK3 metal film, how the signal is raising with volume, there are carbon films Dralorics and some Pihers vintage!
i had good luck with those Jupiter vintage tone caps so they are all in. Rifas for cathodes because i have many.

so from Dumble point of view will be like low plate classic amp..with vibrato and reverb. or like vibroverb with the overdrive!
133.jpg
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pfarrell
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Re: Vibrodriverb special

Post by pfarrell »

Nice work! This is fun to see. I have built a Vibroverb head, with a 15” speaker. It’s a great amp.
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dorrisant
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Re: Vibrodriverb special

Post by dorrisant »

This looks very nice. I would love to see what you have read about making transformers.
"Education is what you're left with after you have forgotten what you have learned" - Enzo
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bepone
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Re: Vibrodriverb special

Post by bepone »

pfarrell wrote: Thu Aug 18, 2022 2:15 pm Nice work! This is fun to see. I have built a Vibroverb head, with a 15” speaker. It’s a great amp.
thx, Vibroverb i like too, i have JBL 15" for that waiting :P
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bepone
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Re: Vibrodriverb special

Post by bepone »

dorrisant wrote: Fri Aug 19, 2022 5:51 pm This looks very nice. I would love to see what you have read about making transformers.
thx, a for the transformers is very long story but good thing is that results are in proportion to your effort, every output transformer is better than previous! :mrgreen: at the end you realize this is not a transformer (although is working like transformer) this is mechanical filter! main factors are L primary inductance, Lp parasite inductance, and Cp parasite capacitance. they are defining your sound with core laminate material too. and are mechanical variables, L depends of primary turns, Lp parasite is pure geometry+number of turns, and parasite capacitance is number of turns and interleaving.
so good read are many, but also is helping to dissasseble some old trafos , like Fender which is simplest one..only P-S interleaving, or S-P-S.

- i liked to read Turneraudio (now is gone, RIP Patrick Turner) but you can download copy od the genious and very complex site here: https://atrad-audio.co.nz/turneraudio/w ... ndex.html-
- old books with sketch of interleaving for output transformers, good for guitar use, like shown here http://livinginthepast-audioweb.co.uk/i ... vxformers3
- experience of some old guys winding the transformers, specially in guitar amps (Marshal etc)
- using of different varnish and nature materials for insulation (like in 50ties)
- hi quality laminations and their characteristics (losses and B-H curve, hysteresis)
- also was one site where were all the popular transformers , a draft sketches how to wind them.. now this site is also gone but i have found something interesting there too
timrobertson100
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Re: Vibrodriverb special

Post by timrobertson100 »

Very nice work. Thanks for sharing the photos and detail
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bepone
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Re: Vibrodriverb special

Post by bepone »

some progress in chassis works, transformers mount, drilled holes for rubber grommets:
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on the pcb , soldered wires and grouped with a little bit heatshrink (also to remember which is which :P ), test fit in chassis. now i see that i will need the middle part of chassis for LND150 transistorised vibrato, so i cant put the standard supply board there.

the first power supply cap with diodes will go in the corner of chassis which is also noise-wise the best position, short distance for higher charging currents from PT to first electrolytic cap, and as far as possible from other circuits which can pickup this noise. in the standard middle part of the chassis i see there is master volume pot and vibrato circuits and i didnt like to put rectifier diodes there. maybe can pass but better in the corner.

g2 electrolytic cap will be on the terminal lugs close to output tubes. caps where chosen to be only one, not 2 in series, so 47uF/500V and 22uF 500V. power supply Ub+ will be cca 460V or 430VDC, there are taps on power transformer.. output tubes didnt selected yet, but plan is something form 6L6 family but stronger , like 35Wattage 7027A, 7581..to have more balls. maybe to put finaly in service some vintage sylvania 6L6GC which are also collecting the dust for decades!
135.jpg
136.jpg
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MeanMrMustard
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Re: Vibrodriverb special

Post by MeanMrMustard »

You sir, are a badass. 8)

Great looking build, board, cab, chassis and all! Would love to hear a clip!
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ijedouglas
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Re: Vibrodriverb special

Post by ijedouglas »

Great looking build, I bet it sounds killer!
Ian
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bepone
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Re: Vibrodriverb special

Post by bepone »

thx guys! i hope will be something from it :)
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