Mounting tubes horizontally

[sonolink]

Hi guys,

I'd like to fit a tube inside a Hammond 1590BB for a guitar tube preamp pedal and would like to do it horizontally using a sub board plugged into the main board. I've seen some Format 500 pres use similar systems because of space, but I can't find anything like that anywhere

Any ideas/links please?

Cheers
Sono

 

[ruffrecords]

It is not a problem. I do it all the time in my tube mixer modules.


Cheers

Ian

 

[dmp]

Are you asking about how to do it mechanically? And an idea for a right angle bracket to hold a tube socket?

 

[Matador]

Any ideas/links please?

We did this on the C12 project: pcb fit into slots, and used SMD pads to make electrical connections between the two sets of PCB's. Strain relief was using cut-off component legs which forms a 45 degree angle.

 

[JohnRoberts]

I think I've seen it done inside inexpensive guitar amps (Peavey). As I recall the engineer put the tube sockets on a breakaway PCB connected to main board by machine inserted jumpers. So basically after the wave solder, break away the board with sockets and then orient it horizontal.

JR

PS: I am not the tube guy here

 

[k brown]

Been running a hot 6X4 in a power supply horizontally for years without any problem.

As far as mechanics, I mntd the socket onto a piece of aluminum angle.

 

[scott2000]

There's a guy on feebay that sells some angled tube sockets...
Little pcbs with 90 degree header pins

 

[Tubetec]

Older fillament based tubes did need vertical orientation or things started to sag ,
fine for modern preamp tubes but I dont think I know of any guitar amps with power tubes horizontal , I would think cooling is generally better in the vertical because the tubes can be placed along the edge of the chassis for better air flow .

 

[mad.ax]

I dont think I know of any guitar amps with power tubes horizontal

Marshall EL84-20/20 comes to mind....

 

[sahib]

I used it on a tube guitar pre-amp in 1U case. I got some angle brackets made. I can supply if it is of interest.

 

[alphasnk]

tubetown has some, i use them in 1u racks as well:

Accessories

 

[Tubetec]

Yes your right Mad , Id forgotten about that one , I see theres a fan to help out with cooling too.
I have the 20 watt Marshall Pa amp from the early 70's , I replaced the dropper resistor in the screen supply with a choke which gave it a more rounded punch on the peaks . I added the treble leak cap across pot on one channel so its the same as the lead 20W in terms of tone . I also made a change to the phase invertor so its more like the 50W circuit without the feedback connection . I think I changed the value of the tail resistor to 15k and added the usual 470 ohm grid dropper with two 1M connected to each grid with a 0.1uf decoupling cap to ground from the second grid . That amp ate tubes until I gave it the traditional 'standby' switch found on bigger amps of its kind . I lifted the centre tap of the HT winding via a toggle switch at the back for convienience of wiring ,it also doesnt create a major bump in the sound output when its turned on or off , merely a slight rushing sound of electrons to the plates reflected into the speaker .

I've seen several amps with power tubes mounted vertically on the PCB , it can be problematic ,over the years the weight of the tubes and the heat tends to warp the PCB and its more prone to scorching/arching than hardwire , . Fender does it well in it in the blues deville/deluxe type amps and the only issue ive found is when musicians try and change a tube mid gig and break the soldering to the socket .

Definately a fan of angle iron brackets for tube mounts with hardwire ,
I grabbed a 10 pack of zinc plated 90 degree structural steel brackets from Lidl for 3.99 euros ,
I clamp it up in a vice and drill out the centre hole to the diameter of the tube socket ,I then mark the mounting holes for the tube socket ,punch then drill the results are faultless every time .
The brackets are 2mm thick , way overkill but it helps conduct heat from the tube to the relatively cold chassis very efficiently .

Bullet holing the panel above and below the tube in a 1U enclosure is always a good plan , but remember to allow some space between adjacent units for air flow . You see this technique used on the tube Danner enclosure/V series, a punched air vent in the vicinity of the tube allowing good air flow up through the enclosure.

 

[gyraf]

..some serious power tubes need to be oriented in a specific direction, no small-signal tubes that I know of needs this..

/Jakob E.

 

[Tubetec]

Mostly you find pre-amp tubes are allowed any mounting position , theres usually a reference to it in the tube data .
Power tubes have heavier grid wires , if the tube is vertical this droop isnt so bad , if its horizontal the clearances between the various electrodes changes more and the characteristics of the tube also change . Obviously if you only have a single rack space vertical mount isnt possible unless you cut a hole in the lid . Id definately avoid mounting any kind of power tube horizontally though , I checked the EL84 data , I didnt see any reference to mounting position , not 100% sure what to infer from that .

 

[My3gger]

Oliver Archut was really good at it, he used pcb for the circuit and then p2p to sockets on L profile. In my experience it allows for simple, efficient wiring with shield where needed, good access, testing and comparisons, ventilation and so on. Breakaway pcb's (as used in mics) would become break-offs in my builds due to lots of testing, knowing how people handle tubes/sockets is another reason for doing it this way.
Mics are the only exception where i prefer breakaway boards, Oliver did show other good methods for this too

 

[mad.ax]

The 'filament sag that might touch the grid' issue was mostly a concern with directly heated tubes.

I have checked a few datasheets from different manufacturers for the most common power tubes used in guitars amps, and I included exemple of commercial products where those tubes are mounted horizontally...

Tung Sol datasheet for 6L6GC : Any mounting position
Exemple Garland, FryetteLXII

RCA datasheet for 6BQ5 (EL84) : Operating position : Any
Exemple Marshall 20/20, Mesa Boogie 2020….

Svetlana datasheet for EL34/6CA7 : Operating position : Any
Exemple Dynachord Eminent

General electric datasheet for 6550A : Mounting position : Any
Exemple : Aguilar DB359

Radiotron datasheet for 6V6GT : Mounting position : Any
Exemple : Silvertone ‘Amp in case’ 1457

 

[Matador]

Mesa used horizontal mounting of beam pentodes in most (perhaps all) of their rack-mount power amps:

 

[sonolink]

Wow guys, thanks a lot for all the feedback!! A lot of good ideas indeed.
I saw this guy's pedals and was trying to figure out how to do it.



I LOVE Matador's concept!! VERY inspiring!!

 

[soapfoot]

You might want to consider cooling in an application like that.

Additionally, microphonic behavior could become a real problem if the enclosure is being stomped on—select tubes carefully!

 

[Tubetec]

The break away pcb that solders on at right angles is fairly rigidly bolted down to deck usually ,
Im looking at dual shock mounting a PTFE tube socket to a PTFE pipe seal washer ,which in turn is shock mounted to the mic frame , the grid and capsule bias components can be placed close to the socket pins on the horizontal section ,components from the anode coupling cap on can reside on the vertical PCB heading in the direction of the transformer . Kevlar reinforced copper wire is looped into small pig tails and used to wire the tube socket to the components , this prevents to a great extent the chance of vibrations being transmitted through solid core wires to the electrodes of the tube . you often see the AC701 and other wire ended tubes often have small springs formed on the lead outs before soldering, its gives more distance from the glass to metal seals when soldering but also helps prevent vibration .

I wasnt saying its not doable , putting power tubes horizontal , just that it often complicates cooling ,
I know a guy , producer , he kept a 5w half rack EL84 based tube amp at the ready in the control room on sessions , it ran so hot you probably could have cooked an egg on the top panel .
If you absolutely have to have a 1U enclosure thats a matter of choice ,