cheap but good SET amplifier? - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 25th October 2004, 07:22 PM   #1
diyAudio Member
 
Join Date: May 2003
Location: USA
Default cheap but good SET amplifier?

I've taken a lot of time off from DIYing amps and such... but am currently not happy with my standard receiver for music. I dealt with headphones for a long time, but am tired of that, so I want to get my speakers up and running with new life from a better sounding amp.

I've heard a lot about digital amps- how warm and "tube-like" they are, so I thought I'd build or buy one of them. But, why spend money and time building something that is only going to sound like tubes... Like my father always said, "why buy something that is going to be LIKE something else... just get what you want to start with." So, I figured I'd just do that.

I saw that Bottle head was re-releasing its S.E.X. kit, which would be nice, but $400 is WAY too much for me to spend right now on a 2W amp. I am looking to spend more like $100 or so right now...

My main speakers are Klipsch RF-3's, which are 98dB @1W/1m. I am actually about 1m away, too, so no issues there. I measured the voltage across the speakers under my normal listening conditions and found that they were drawing around 0.1V continuous with 0.3V peaks. Not much... so I can easily get away with a low-powered amp, which is what I'd like. Less than 3W would be plenty, even allowing a little overhead.

I found a couple of amps that look as though they might fit... but would kind of like some comments/pointers that would be useful to know. If possible, I would also like to have the amp adapted for use for headphones whenever I wish, like the S.E.X. kit is. That was a very good point of that amp, but the price killed it for me. I am getting rid of all my other headphone amp stuff, and I'd like one simple SET amp for my speakers that would also work with my headphones (Sennheiser HD580, 300-ohm). How might I adapt most transformer coupled amps to run these?

I found a few amps that looked ok, but if there are anymore I didn't see, please point them out. The ones I saw are:

the Miniblock
half-watt 6EM7 amp
and one here on the forums- Morse's 6BM8 SEP amp. Not SET, but I suppose it might work...

The half-watt I am not sure about. I wouldn't use the power tranny outputs, but I am concerned about it not having enough power.

Any thoughts, comments, or other suggestions are welcome. Thanks all!

EDIT: Forgot to mention... simplicity also highly preferred. I would actually prefer a design using dissimilar triodes as shown in the links.
  Reply With Quote
Old 25th October 2004, 07:38 PM   #2
diyAudio Member
 
Gabevee's Avatar
 
Join Date: Feb 2002
Location: Richmond, VA.
Hi There,

This is going to sound hard, but not meant to.

My suggestion? Save your money until you have the $400. Halfway decent iron for an SET amp that'll give you 2 watts per channel will cost $100 alone. That is, about $35 for the power transformer, and between $25 and $35 apiece for the output iron. Decent output tubes, if you want to do triode, go for the 2A3 for about $50 a pair. Otherwise, the 6BQ5/EL84 is decent for SE. They go for about $17 to $24 a pair. Then a decent 12AX7 (some wil shout "NO! NO! The 12AU7!). But we are using one dual triode to drive both output tubes. That will be another 10-30 bucks, depending on whether you want OK sound or very good sound.

So look to spend a total of about $230 for parts you buy yourself... oh, not counting the chassis and hole punching and... time.

Hope this helps.

Gabe
__________________
Gabe CGV Electronics
Home of the CGV-300B amplifier on a budget
  Reply With Quote
Old 27th October 2004, 12:50 AM   #3
diyAudio Member
 
Join Date: Aug 2004
Default Magnavox SE 8303 console amp!

Hi needtubes,
Here is a link regarding some Magnavox console 6BQ5 amplifiers.
I think that this could be a good place to start, playing and experimentation with various system configuration is half of the fun.
I have heard a few of the PP Magnavox units over the years, and I liked it.
I hope this will help, it should be fairly cheap when you track one down.
Good Luck
Norris Wilson

http://65.219.61.150/forums/showthread.php?t=25583

PS. I like your moniker, for I think I need tubes too.
  Reply With Quote
Old 5th November 2004, 07:02 AM   #4
Ori is offline Ori  United States
diyAudio Member
 
Join Date: Oct 2004
Location: San Jose
Default How about a single-tube OTL amp?!

At less than 1 watts into 8 ohms, your amp needs only 8V peak-to-peak, so the main issue would be getting the 1A (p-p) of current. You'll need a big tube like a 6336A, so the power tranny will be big, but that's the cheaper of the iron parts...
You will need a power resistor for the plate load and a decent output cap (low voltage, so it's not super expensive!)
If you can settle for 1/2 a watt per side, then run each of the individual triodes one per channel. Notice that the gain is low but just enough for a direct feed from a line-level source like CD player. Your stereo amp may end up being a single tube...
Other regulator tubes like the 6080 and 7233 might be good candidates for the same topology.
Have fun!
  Reply With Quote
Old 5th November 2004, 07:24 AM   #5
JZatopa is offline JZatopa  United States
diyAudio Member
 
Join Date: May 2003
Location: Chicago
check out www.decware.com. They have a kit version of the zen that is about $399. It is an amazing amp.
  Reply With Quote
Old 5th November 2004, 08:56 PM   #6
mcs is offline mcs  Denmark
diyAudio Member
 
Join Date: Aug 2003
Location: Denmark
Why not just try Fred's Miniblok? The parts are cheap, and the amp is easy to build. You can always buy a bigger/better output transformer later. But even SE amps with small transformers sound fine to me...

Best regards,

Mikkel C. Simonsen
__________________
My personal electronics website
Remote control kits website
  Reply With Quote
Old 5th November 2004, 11:01 PM   #7
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Quote:
Originally posted by Gabevee
Halfway decent iron for an SET amp that'll give you 2 watts per channel will cost $100 alone.
Maybe if you are buying new...

A Decware ZEN clone (which we have dubbed Mulligans -- Bogus ZEN -> Bogey -> Mulligan) can be built using something like these vintage RCA OPTs -- average sell price so far is about $30.

http://cgi.ebay.com/ws/eBayISAPI.dll...tem=5729672936

(disclaimer: i have everything to do with this auction, me & my wife are planetsofta)

And i have a ton of similar, but nicer, European iron. A friend recently built an amp inspired by the Dec ZEN but with an ELL80 (2 EL95s in a single envelope). The OPTs were quite small so bass is limited, but everywhere else it sounds quite good (he is very surprised at how good)

http://www.decware.com/cgi-bin/yabb/...num=1098310730

excluding the fact that i gave him the donor (out of a Normende console -- OPTs often called Telefunken -- i'm accumulating favours towards kitchen cabinets), he has $30-40 CAD into the whole amp.... and a lot of that was going out and buying a new Hammond chassis instead of heading to Value Village and finding a suitable "round" chassis.

With attention to Frugal-phile(tm) directives a $100 USD triode strapped pentode SE should be very doable.

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
good value (i.e. cheap) OPT in uk? adamus Tubes / Valves 6 11th November 2008 08:55 AM
good cheap T4P cartridge? DragonMaster Analogue Source 49 4th July 2007 03:50 AM
Good switch for Stepped attentuater, Good cheap RCA jacks pjpoes Parts 20 10th March 2005 08:47 PM
reasonably cheap reasonably good active xo Ignite Car Audio 7 18th November 2004 03:05 PM
Uber good, just a little less cheap. JoeBob Multi-Way 22 22nd October 2003 05:11 PM


New To Site? Need Help?

All times are GMT. The time now is 06:42 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2