No-C SAKUMA PRINCIPLE AMPLIFIER
with EML520B and 300B-XLS
Designed by Robert t.H, from Nashville USA.
2) 300B-Mesh driving 520B or 300B-XLS
From: Robbert <xxx@xxx.com>
Sent: Sonntag, 10. Dezember 2023 21:16
To: Jac van de Walle <jac@xxx.de>
Subject: Re: EE 27 board and LL1677
Good Day Jac:
Yes the amplifier is working great.
The current setting for the 300B XLS is 41mA and the 520B is 90mA. It sounds really nice with these settings. Hope with these relaxed settings I will also have a long life of the tubes. I have never heard mids so clear, like woman voices and spanish guitar. Every note and instrument is standing by itself with air around it. This all is played through a DIY Tannoy corner GRF with the 3833 driver from Tannoy. Amp is dead quiet. No noise is noticeable by ear even when my head is almost in the speaker. The amp is driven by a SE preamp with the #26 tube.
I incorporated your suggestion to put the bias voltage through the grid input transformer. This trick took the caps out of the signal path.
All transformers are Lundahl, and the output transformer LL1623 has the EE15, EE16 and EE17 board and the 1677 has the EE27 board, and the 1670 grid choke has the EE08 board, the boards are so easy to use and the wiring looks so clean.
In relation to the transformers I have the first transformer also connected out of phase so the speaker is in Phase again due to the LL1677 also being out of phase connected.
I made two power supplies, one for the drivers section and one for the power section. (I had quite some extra parts in a shoe box)
The C3m is the Telefunken I bought from you. From a sound perspective there was no noticeable difference in sound when exchanging it for the Siemens ones I had already.
The 100 ohm resistor you see at the speaker terminals is an old habit. Yes I lose some power but also save my output transformer if my speaker ever got unnoticed unhooked.
I could not have put this amp together without your excellent web site like the GM70 SAKUMA style amp pages and your power supply pages.
I have attached the schematic as is today. If you would like to use it for other DIY folks, please go ahead.
Now I am thinking about getting an EML 20B but use it with the LL2790 25mA since I have that one already. This would make the whole chain DHT except the RIAA pre amp.
Have a great Day.
O yes the Tornado from last night was in the north of Nashville I live in south of nashville.
Kind regards
Robbert
On Sat, Dec 2, 2023 at 5:36 PM Jac van de Walle <jac@xxx.de> wrote:
Hi Robbert,
you are right about this! The programming if EE27 Board should be: 3, 5, 12, 17, 28, 30, 47, 51, 53, 58. I have already put this online.
L2 is in general the ground connection with this configuration. Then, bridge 47 connects L2 (ground) to T. Meaning T becomes grounded.
But when you want to use T for ground it’s the same.
Please let me know if it works now, but I can’t answer you before Monday.
Best regards,
Jac