Anderton '64 reissue JTM145 - any info?

[Smokebreak]

Yes, I understand that, but the divider I'm talking about is the Lpad-type divider that only occurs on the 16ohm side....the 18r and the 82r.
The 8ohm side only has series resistance, and then , like you said, the speaker .
I guess I'm just very unfamiliar with how they came up with these numbers, and this process of attenuation, as Lpad values would be much smaller.

[roberto]

The 8ohm side only has series resistance, and then , like you said, the speaker .

that's not what I said. I said the opposite. 8 ohm tap has 18 ohms on the 16 ohm tap, when in 8 ohm mode.

The 18 ohm is de facto in parallel with the 47R + 8R.
This is in my opinion a smarter attenuation than the standard low values lpad.

I hope you can see it.

If so, try to calculate the attenuation.
Start calculating the percentage of current flowing through the speaker, then the power.

[Smokebreak]

Ah I think I see it know, as I have neglected continuity on the secondaries I will have to wait until my brain swelling comes down before I approach calculating attenuation

[Matec]

Hello
The resistor of 18 ohms has the function of keeping the impedance of the OT within acceptable values for the 12AU7.
Thank you.

[Smokebreak]

Hello Matec! Very good to see you here, and very nice work with the schematic. How do you like the amp?

[Matec]

Thank you.

I like the sound. He has strong treble and bass present. The last change in the resistor R33 made came medium which softened the sound. It sounds like the original, just do not answer the OTs built here, leaving the sound shrill treble.
Unfortunately I'm not a guitarist to make videos with sound samples, but soon I will have someone to do them.

[Matec]

Thank you.

I like the sound. He has strong treble and bass present. The last change in the resistor R33 made came medium which softened the sound. It sounds like the original, just do not answer the OTs built here, leaving the sound shrill treble.
Unfortunately I'm not a guitarist to make videos with sound samples, but soon I will have someone to do them.

[Matec]

Thank you.

I like the sound. He has strong treble and bass present. The last change in the resistor R33 made came medium which softened the sound. It sounds like the original, just do not answer the OTs built here, leaving the sound shrill treble.
Unfortunately I'm not a guitarist to make videos with sound samples, but soon I will have someone to do them.

[Matec]

Sorry for the repeated posts. There was an error message, and I felt I had failed to send them.

[roberto]

Nice work Matec.
Yes, the nice part is that they use the 18W for both taps.

It is like we have a 9 ohm resistor in parallel with 47+8 ohm on the 8 ohm tap.
9//55 = 7,74 ohm so basically 8 ohm
We have 1/7th of the total current flowing through the 47+8 ohm path.
Furthermore, the speaker sees only 1/7th of the voltage from the 8 ohm tap.

So we have something like 1/50th of the available power with the switch engaged.

[Matec]

Thank you.

Yes, the 18R resistor on tap 16 Ohms, or 9R resistor in 8 Ohm tap has the same effect, keep the impedance at a value close to 18k or 20k in the primary.
The attenuator resistors are in series with the speaker
Depending on the speaker can be a loud sound.

[Smokebreak]

Nice work Matec.
Yes, the nice part is that they use the 18W for both taps.

It is like we have a 9 ohm resistor in parallel with 47+8 ohm on the 8 ohm tap.
9//55 = 7,74 ohm so basically 8 ohm
We have 1/7th of the total current flowing through the 47+8 ohm path.
Furthermore, the speaker sees only 1/7th of the voltage from the 8 ohm tap.

So we have something like 1/50th of the available power with the switch engaged.

Ah! This is making sense to me now. Thank you guys!

I did some drilling and mounting last night. This has to be the smallest OT I have ever seen! Even though its only 3W OT, I can't help but be skeptical.
I also did a chassis layout. I still need to draw in the switching.

[johnnyreece]

This looks SOOOO interesting...I just finished up my lower powered amp...ready for a new one.

[Matec]

Smokebreak

If you allow me a correction, C21 is 2.2 nF.

Great layout.

Good luck with your amp.

[Smokebreak]

Thanks Matec. I have updated the layout.