From: bill@verdix.com (William Spencer)
Subject: Re: Homebuilt amps?
Organization: Verdix Corp.
Date: Fri, 10 Apr 1992 20:57:19 GMT

In article <1992Apr9.211029.23540@minyos.xx.rmit.oz.au> s893971@minyos.xx.rmit.oz.au (Volksie Wagen.) writes:

>Bill, why are tube amps so expensive? is it the sheer amount of parts that
>hikes the price way up? 

If you've ever investigated the prospect of going into buisness for yourself
you'd think they're cheap! As for homebuilding, I expect I have put in 
about $1200 of labor on each of my DIY amps.

>From: larryh@cabezon.uucp (Larry Huntley)
>>Bill, why are tube amps so expensive?
>	One reason is that the parts for these beasts are becoming scarce.
>	Electrolytic capacitors of the proper voltage (usually 450V) are
	hard to find,

Panasonic, from Digi-Key. Superior. Over 450V is more difficult.

> power transformers of the 350-0-350 w/filament winding
>	variety are not growing on trees

Well, not every electronics distributor stocks them any more, but that doesn't
make them rare.

>	People - this CAN be done.  It is not difficult for someone with
	a fair amount of homebrew construction experience (NOT KITS.)

But I think the kit idea is better for most, to the degree they are availiable.
It's simply impossible to prepare someone for every subtle detail they will
have to deal with in building an amp.

>       However, unless you are prepared to spend a considerable amount
>        of time and expense tracking down parts and tools, I would recommend 
>	buying a used amp just to see if the tube sound is really what you
>	want. 

Seriously. Can't buy a Boogie, get something else (better? ;-) ).
You can also combine components if you're on a budget. Simple
mods can be valuble and easy -- you might even find someone willing to do them
for you for reasonable price. One possible mod is to simply provide a direct
power stage input to drive from your wiz-bang modern preamp.

>From: dam@dcs.glasgow.ac.uk (David Morning)
>Valves themselves are also expensive at anything between 17 and 45 UK pounds
>for a single EL34 (~$30-$80 US). You need 4 for a 100 watt amp.

What?? Maybe for high-end relabeled selected reselected boutique stuff.

>for most of us, It's just designs cribbed from other designs put together to
>suit ourselves.

Tube amps are certainly the easiest to patch pieces together. Most "experts"
aren't exactly PhD's. The only problems are high voltage (probably less likely
to be shocked when you have a healthy respect for the voltage though!) and
it's hard to do much in the starter, headphone amp range.

The basic preamp building block couldn't be simpler. You need to settle on a
gain structure, controls, layout, grounding design, power supply, power stage
configuration, get the parts and build it and put it in a box to make an amp.

>                   The Tube Amp Book Vol.3
                    by Aspen Pittman
                    Published: Groove Tubes/GT Electronics
                               12866 Foothill Blvd.,
                               Sylmar,
                               CA 91342

Also availiable from Antique Electronic, see below.

>>>>From: kew@cbnewsg.cb.att.com (steve.w.askew)
	First the most expensive thing in a tube amp is the transformer's.
	You need at least 2. The power supply transformer is probably going
	to run at least $100 to $180. The output transformer will probably
	run from $80 to $120 depending on the demand of the circuit.

I got a factory replacement Bassman output tx in 1983 for about $40.
Source is Chicago Music.

	You can find Bassman or BandMaster heads all the 
	time for about $150 to $200.

My Traynor heads were $50 and $10. Warning however, Traynors seem to always
have an induced hum across the chassis. Not always a problem.

I recommend low power amps. Cheaper and better sound. Most makers aren't that 
serious about them though. That is changing.

Useful stuff to follow.

Bill S.
---------------------

Anyone interested, these guys can save you some serious bucks:

Antique Electronics Supply
(Antique Radio Supply)
688 First St.
Tempe Arizona 85281
602 894 9503

Tubes, high-volt capacitors *at reasonable prices*. Radio speakers to 12",
books, transformers, supplies relevant to tubes and old radios. 


Triode Electronics
2010 Roscoe St. 
Chicago, IL 60618
312 871 7459

Tubes, transformers, enclosures, etc.
 

Old Colony Sound Lab                   Audio Amateur Publications
PO Box 243                             (_Glass Audio_, AA, Speaker Builder)
Peterborough, NH 03458                   PO Box 576, etc.
603 924 6371                            603 924 9464

Amp kits: (probably not guitar?)
Mark V Electronics
8019 E. Slauson Av.
Montebello, CA  90640
orders: 800-423-3483
info: 213-888-8988