schematic from this amp 45/717a/5u4.. - 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 11th July 2004, 11:40 AM   #1
sonix is offline sonix  Germany
diyAudio Member
 
Join Date: May 2004
Question schematic from this amp 45/717a/5u4..

hi,

have anyone the schematic from this amp?

yamamoto a-08

thanks
sonix
  Reply With Quote
Old 11th July 2004, 12:42 PM   #2
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Default Re: schematic from this amp 45/717a/5u4..

Konnichiwa,

Quote:
Originally posted by sonix
have anyone the schematic from this amp?

yamamoto a-08
The Web Pages contain enough high rez photos of the innards to reverse engineer the schematic, so have a go.

Start with these, rotating them to be readable:

Click the image to open in full size.

Click the image to open in full size.

Then look at the picture of the circuit in thius PDF - zoom in:

http://www2.117.ne.jp/~y-s/A-08ura.pdf

Another hint, electrially the 717A and the C3m are not miles away.

Sayonara
  Reply With Quote
Old 20th July 2004, 01:28 PM   #3
rafalc is offline rafalc  Hong Kong
diyAudio Member
 
Join Date: Sep 2003
Location: Hong Kong
There is full schematic in August MJ Audio

Rafal
  Reply With Quote
Old 14th December 2004, 11:50 AM   #4
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Konnichiwa,

I have decided to post the Schematic in another on-line group with pretty complete detail, so also find it here, in context. It is basically 99%, one or two values may be slightly different, but not much.

If you want to copy the Amplifier you do of course need the iron, considering fit/finish, component quality and inclusion of NOS Valves I'd think it's worth giving Yamamoto the business and buying the Kit if you want to build the Amplifier, a Set of Tamura Transformers and a nice case plus the valves will take most of the cost of the kit.... ;-)

Sayonara
Attached Images
File Type: gif yamamoto a08 schema.gif (16.3 KB, 3100 views)
  Reply With Quote
Old 9th February 2008, 07:53 PM   #5
kmtang is offline kmtang  Canada
diyAudio Member
 
kmtang's Avatar
 
Join Date: Nov 2004
Location: Vancouver
Default Lundahl LL1620 SE 30mA OPT for 45 tube

I found that even the output power of the 45 tube in SE mode is only 1.5W, it has the advantage over the 2A3 and 300B because its idle current is only 30-35mA. I built two 45 amps with LL1620 and LL1620AM which is specified to work at 30mA. According to the datasheet, the primary inductance almost 100H. Most of the SE OPT for 2A3 and 300B are with approx 24-30H primary inductance.

After listening to these two amps in about 2 months time, I noticed that its bass response is excellent.

My friend just bought the Yamamoto 45 amp. I would really like to hear it to see what are the differences between Yamamoto and mine. BTW, my 45 amps are using 6SN7 for the driver which is the design from Sun Audio's 2A3 SE amp.


Johnny
  Reply With Quote
Old 12th June 2010, 07:40 AM   #6
codyzox is offline codyzox  Serbia
diyAudio Member
 
Join Date: Jun 2010
I need it also...Can someone post details with original shematic and parts list (also from which manufacturer are parts exactly). It would be a great help, not just for me i think...Big thanks in advance...
  Reply With Quote
Old 14th June 2010, 06:40 AM   #7
codyzox is offline codyzox  Serbia
diyAudio Member
 
Join Date: Jun 2010
Quote:
Originally Posted by kmtang View Post
I found that even the output power of the 45 tube in SE mode is only 1.5W, it has the advantage over the 2A3 and 300B because its idle current is only 30-35mA. I built two 45 amps with LL1620 and LL1620AM which is specified to work at 30mA. According to the datasheet, the primary inductance almost 100H. Most of the SE OPT for 2A3 and 300B are with approx 24-30H primary inductance.

After listening to these two amps in about 2 months time, I noticed that its bass response is excellent.

My friend just bought the Yamamoto 45 amp. I would really like to hear it to see what are the differences between Yamamoto and mine. BTW, my 45 amps are using 6SN7 for the driver which is the design from Sun Audio's 2A3 SE amp.


Johnny
Have You compared them?
  Reply With Quote
Old 14th June 2010, 08:45 AM   #8
diyAudio Member
 
Join Date: Aug 2008
Am I the only one here that finds this schematic not compelling?
Unbypassed zener string, Pentode driving a triode, ewwwww! Ok, the transformers and the cherry wood and the finish are sexy, but it really looks like somethinh an amateur would design. (How am I going to drive the DHT, it needs a lot of voltage! Oh! I ll just stisck a Pentode it has all this nice voltage gain!!!!)
  Reply With Quote
Old 14th June 2010, 04:42 PM   #9
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Quote:
Originally Posted by costis_n View Post
Am I the only one here that finds this schematic not compelling?
Unbypassed zener string, Pentode driving a triode, ewwwww! Ok, the transformers and the cherry wood and the finish are sexy, but it really looks like somethinh an amateur would design. (How am I going to drive the DHT, it needs a lot of voltage! Oh! I ll just stisck a Pentode it has all this nice voltage gain!!!!)
While I understand your objections and would have completely agreed not too long ago I have to mention that I have heard several similar amps that sounded surprisingly good in fact. (IMHO I think in a lot of cases a single stage driver is preferable to several cascade triode stages in terms of resolution if there is sufficient drive capability available. Here I would probably use a single 5842/417A triode myself.) Given the voltage levels on the screen of that pentode I would be surprised if you could hear a difference in noise levels bypassed or unbypassed. You might want to try it before dissing it, once having done so you have more than engineering dogma and opinion to base it on.. (I have been all too guilty of the same things, so please don't take my comment too seriously..) FWIW
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan

Last edited by kevinkr; 14th June 2010 at 04:45 PM.
  Reply With Quote
Old 12th October 2011, 04:05 PM   #10
diyAudio Member
 
directdriver's Avatar
 
Join Date: Nov 2005
Quote:
costis_n: "Pentode driving a triode, ewwwww!"

What's wrong with using pentode? Have you listened to it or an amp using pentode driving a triode? Didn't the Western Electric 91 use the same thing? If designed right, I don't see any reason to object to it.

.
  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
Matched pairs 717A Western Electric/Tung Sol phrarod Vendor's Bazaar 1 19th October 2007 08:15 PM
NAD 304 Schematic Makofoed-6sn7 Solid State 5 3rd May 2006 06:41 AM
717a plate volts 845amp Tubes / Valves 6 30th December 2005 11:22 PM
717a Datasheet mrstone Tubes / Valves 7 5th August 2004 05:05 PM
What do you think about this schematic? PanzerLord Solid State 9 8th March 2004 06:43 PM


New To Site? Need Help?

All times are GMT. The time now is 04:34 AM.


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