Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kagliostro on May 27, 2013, 05:49:27 am
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Is this old and never more used layout the Ultimate Layout ?
This way the connections between components and tubes can be very short
and also is easy to use a pipe to shield each tube component ensemble from other tubes components
Can this be a way to build the amp in a better way ???
Crazy question
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in the past a similar version was also used for guitar amps (see the bottom attached image)
and here
http://www.radiodaze.com/product/15451.aspx (http://www.radiodaze.com/product/15451.aspx)
http://www.radiodaze.com/category/425.aspx (http://www.radiodaze.com/category/425.aspx)
K
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These (and a few other similar schemes) were widely used in the early days of tube-built computers. I recall seeing a few of those in my wanderings on Radio Row, when I was a kid, in NYC, where the WTC was built. If you think about it, one tube plus those components is in essence a primitive integrated circuit. One could easily envision a complete flip-flop built with a 12A*7 or any number of twin triodes. I think 12AT7/6201 were widely used. I'm not aware of audio stuff built using those plug-in things, but it's certainly possible. There are stories from those days of people with shopping carts of tubes and probably those kinds of plug ins, walking around the ENIACs and on standby, replacing tubes all the time.
There are some positives and negatives. Obviously, the main chassis wiring can be super clean...but all of your plates are pretty close to all of your grids...and, if one or more preamp stages was TOO noisy and you COULD NOT get rid of the noise except via building in the more conventional way...keep leads close to chassis, separate grids from plates....than that stage, you would have to build with the parts in the chassis....so what's the point of having 3 stages built with the plug ins and one stage built in the chassis? Net-net-net, I think building that way would increase, not decrease noise. I believe the main idea behind that form factor is to provide quick replaceability, just like troubleshooting, today (and for the past 20+ years) is generally a matter of isolating an issue to one board and swapping it out, then fixing it back in the shop or sending back to the mfr.
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The modular tube circuit looks similar to some old digital equipment I've seen a long time ago. One module might be a flipflop. Put eight modules side by side for an 8 bit shift register or 8 bit counter. I've also seen some plugin modules that held two 12AX7s that were sitting on an octal socket.
The saddle style tube sockets from radiodaze.com were very common in VHF and UHF receivers and transmitters. I've actually worked on some FAA receivers that used those sockets. I had considered using them in a guitar amp at one time. But for audio work it's hard to beat the turret board construction.
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Probably somewhat more practical are the old vector sockets...and IMO one could make the case that these might get parts closer together if that's the concern. I myself have never used them.
(http://i172.photobucket.com/albums/w32/ttm4/vector_socket_zps88eac5aa.gif)
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RicharD and i built an amp with those vector brand turret sockets that eleventeen posted. an all octal spin on a AB763 super-reverb with the humble-like gain stage. it works OK, it's just not all that; not one of our better designs/layouts. soon after it was built, it was basically placed in storage. i need to strip it for parts and/or scrap it sooner or later.
--pete
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That Vector brand socket is what I was calling a saddle style socket.
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Those of the image I attached (both the last one), as labeled, where IBM parts and the use was in the first computers as you say
and, yes, as you say, thinking about it, may be the grid components too near the plate can be a source of problem
so the plug in component will have a large test before to reach a satisfactory result
However was interesting to see amps build like in the image I attached at the bottom of the previous message
that uses those special sockets
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I've find a not better specified Revox unit that used a similar layout
K
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God help you if you get a component failure on the backside of one of those turrets, right next to the chassis and behind all the other parts. Especially with the sockets riveted in. That could be ugly, and if the filament and tube-to-tube wiring is tight (as it should be) you may not be able to get to those parts without desoldering many other parts.
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> a component failure on the backside of one of those turrets
The IBM unit in the TOP photo, you just pull the whole module out, throw it on Steve's pile, and take another module out of spares.
Those Revox chassis, and most vector/saddle sockets, do appear to be "build only", nightmare repair. They get a lot of parts into a small box by doing most of the assembly in per-tube units, but the final wiring and *riveting* show they were not made to be fixed.
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The IBM unit in the TOP photo, you just pull the whole module out, throw it on Steve's pile, and take another module out of spares.
Yes, the nice thing was really that
K
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How about this from Tone King?
Brad :icon_biggrin:
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Ciao Brad
Never seen something like that
seems they have a standard "triangoular" double PCB
and that they build on it separated pieces of the circuit (may be related to a single tube)
Interesting
K
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:think1: If you build something like that, you're on your own if it needs debugging! :l2:
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layout is certainly an efficient use of space. i wouldn't want to work on it though... <eek!>
--pete
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Clever. No idea if it is functionally any better than any other approach.
There are a number of ways to arrange wiring if you think 3-dimensionally instead of 2-dimensionally. As always, you may have to question how easy it will be to repair in the future.
The Tone King looks like all components should be relatively accessible, but I can't tell for sure without it in front of me.
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I've never seen that format of circuit construction. I agree with HBP, that's quite clever. Ultimately it is not much different than a single turret board, and it doesn't look any more or less difficult to troubleshoot than a flat one piece turret. It's basically 4-5 separate turrets, that's all. I like it.
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:think1: If you build something like that, you're on your own if it needs debugging! :l2:
:laugh:
I'd like to see a better picture of the bottom board. If you look at the 3rd 1 from the left it has a small bolt and nut that looks like it might be how he mounts it to the tube socket? I can't see if the bottom board drops over the socket pins and is soldered directly to them?
You'd need a cad program with 3D capability to do your drawings.
Brad :think1:
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seems they have a standard "triangoular" double PCB
and that they build on it separated pieces of the circuit (may be related to a single tube)
Ciao K,
I think the bottom board is slightly different because he needs to solder it up to the socket pins.
Brad :dontknow:
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On further examination, it looks like it would be a nightmare to replace parts with that board system.
All the wire connections appear to be made on the upper board, meaning you may have to unsolder those to get to components the wires hang over.
Further, the boards are through-hole, so to remove a component you'll have to heat 2 solder joints at the same time. To add a new replacement component you'll need to remove all solder from the through-holes, then have at least 3 hands: one to hold the component still with its leads in both holes, one to hold the iron, one to solder.
Yes, the work-around is to bend the lead of the new component to the side in the top hole, but that may impede your ability to feed a wire back into the same hole.
So serviceability seems poor though use of space is very good.
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a closer look - the are upper and lower deck PCBs and the sockets are PC leaded types soldered to the lower deck from underneath. the tube protrudes in the chassis & the tube shield base is also attached to the lower deck. 3 screws attach each module to the chassis.
as already stated, parts are installed in plate through holes. to replace defective part; cut the part out, remove remaining leads, evacuate plate through holes & install new part.
replacing a socket would be a total b!#ch...i believe that's the achilles heel with this layout.
service whole module; remove connecting wires and 3 screws.
i wonder if the designer is/was a biker who likes trikes...
after some reconsideration, a lot of vintage point to point stuff where components are buried under others seems like would be/is more difficult to service; some of the danelectro stuff i've worked on and own comes to mind.
--pete
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Looking around I've find two closer images of the Tone King Imperial
seems that is very similar to the IBM concept, but they used larger surface (triangular instead of rounded) for the components
of course this aren't a swap in/out mounts
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I would not like to have to service such a unit
(look to the wite big sand resistor - or maybe a small relay - mounted between the two boards on the right)
K