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-   -   schematic from this amp 45/717a/5u4.. (http://www.diyaudio.com/forums/tubes-valves/37619-schematic-amp-45-717a-5u4.html)

sonix 11th July 2004 11:40 AM

schematic from this amp 45/717a/5u4..
 
hi,

have anyone the schematic from this amp?

yamamoto a-08

thanks
sonix

ThorstenL 11th July 2004 12:42 PM

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:

http://www2.117.ne.jp/~y-s/images/A-...setu-j-2-s.jpg

http://www2.117.ne.jp/~y-s/images/A-...setu-j-1-s.jpg

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

rafalc 20th July 2004 01:28 PM

There is full schematic in August MJ Audio

Rafal

ThorstenL 14th December 2004 11:50 AM

2 Attachment(s)
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

kmtang 9th February 2008 07:53 PM

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

codyzox 12th June 2010 07:40 AM

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...

codyzox 14th June 2010 06:40 AM

Quote:

Originally Posted by kmtang (Post 1424132)
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?

costis_n 14th June 2010 08:45 AM

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!!!!)

kevinkr 14th June 2010 04:42 PM

Quote:

Originally Posted by costis_n (Post 2216048)
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..) :D FWIW

directdriver 12th October 2011 04:05 PM

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.

.


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