Anyone have example of dumble type OD on to tweed 5F6A-part II

[tubenit]

My choice is among of 12AY7 and 12AT7. With both of them I receive a good balance between distortion level and overall sound volume-clean channel.

Sounds like some decent progress!  Congratulations!

Yes, please keep us posted.

With respect, Tubenit

[adamG]

Yesterday, I found here https://robrobinette.com/5F6A_Modifications.htm PPIMV type 3 and I provided that.
It works;) Now, the amp becomes versatile, in my personal opinion. With 12AT7 onboard -OD stage-the whole idea of Dumble style OD tube within Bassman Tweed Era is great solution!
The only issue for now is to verify the amp power output. It is guieter to my ears, because of the PPIMV . If so, I'll apply "regular" MV.
Could anybody share the experience in this matter?

Thanks in advance.

Regards,

adam

[tubenit]

Adam,

I have used all 3 of these types of "master volumes".  My favorite is the active FX.  So, if you could give up the reverb, you could use that tube to do an active FX.  I like the PPIMV next and then the typical Marshall style MV.

All 3 sound great to me. 

IF you look at post #2 on the thread,  it shows what I am using for a FX master volume for it using a single triode.

With respect, Tubenit

[jazbo8]

With 12AT7 onboard -OD stage-the whole idea of Dumble style OD tube within Bassman Tweed Era is great solution!

Have you tried 12AX7 instead of the 12AT7? Just curious about the tone and feel...

[adamG]

With 12AT7 onboard -OD stage-the whole idea of Dumble style OD tube within Bassman Tweed Era is great solution!

Have you tried 12AX7 instead of the 12AT7? Just curious about the tone and feel...

Yes, I did. For me there are two parallel things of importance.First, gain character/sonic, second is volume level when OD activated.
With 12AT7 I receive good portion of distortion without of huge kick of overall volume level, as it is with 12AX7.
I've applied MV type 3 also.That mod gives me pretty good control of the amp volume.
Because of this build and my experience of it, I may recomend that solution of classic Tweed Bassman with OD stage.
I tested/compared Tweed Twin and Tweed Bassman yesterday. To my personal taste,the sound character of Twin is...beatiful.I mean clean sound, of course. There was really something within it;).Bassman is great amp, but I value Twin higher,a little bit.

Regards,

adam   

[jazbo8]

Thanks, may be the 12AT7's non-linearity has something to do with it, i.e., you get much higher distortion without turning up the volume/gain. I will have to try it one day if I ever build a Twin.

[jojokeo]

Yesterday, I found here https://robrobinette.com/5F6A_Modifications.htm PPIMV type 3 and I provided that.
It works;) Now, the amp becomes versatile, in my personal opinion. With 12AT7 onboard -OD stage-the whole idea of Dumble style OD tube within Bassman Tweed Era is great solution!
The only issue for now is to verify the amp power output. It is guieter to my ears, because of the PPIMV . If so, I'll apply "regular" MV.
Could anybody share the experience in this matter?

You have failed to include the value of the ppimv dual-ganged pot you've used? You must remember to still observe the tube's guidelines on the maximum grid leak resistance whether using the pot or plain resistors. Many follow some recommendation or website without thinking about their own situation. See attachment for running 6V6s as an example.

[sluckey]

Leo ignored that data for the DR.

[jojokeo]

He seemingly used 220k on most everything whether a champ/single ended or pp cathode or fixed bias - didn't matter to him. Seems like one of those generic decisions where he just did the same thing on.

[adamG]

Thanks, may be the 12AT7's non-linearity has something to do with it, i.e., you get much higher distortion without turning up the volume/gain. I will have to try it one day if I ever build a Twin.

I allow myself as a diyer to think in a very personal way. I'm not any kind of professional man on this field. So, I simply manufacture something for pleasure. Nothing more. I do not fill myself to argue. I just follow what I want to make;)
I love vintage sound. Tweed Era amps souds beautiful. Try one.
I think that's a good point to go back to idea of 12AX7 and to get higher distortion without the volume turning up. Recently, I've been busy with another build. It's Sluckey's JTMxx of 18W.   

Best Regards,

adam

[adamG]

He seemingly used 220k on most everything whether a champ/single ended or pp cathode or fixed bias - didn't matter to him. Seems like one of those generic decisions where he just did the same thing on.

Hi, I'm opened for suggestions. Therefore, what PPIMV curcuit do you propose for this amp?
Thanks in advance.

Regards,

adam

[adamG]

My choice is among of 12AY7 and 12AT7. With both of them I receive a good balance between distortion level and overall sound volume-clean channel.

Sounds like some decent progress!  Congratulations!

Thank you very much!
I got that amp working because of your patient and constant assistance.

Best regards,

adam

[jojokeo]

He seemingly used 220k on most everything whether a champ/single ended or pp cathode or fixed bias - didn't matter to him. Seems like one of those generic decisions where he just did the same thing on.

Hi, I'm opened for suggestions. Therefore, what PPIMV curcuit do you propose for this amp?
Thanks in advance.

Regards,

adam

Is the one you're using like the one in the photo below? If so, then the value is fine

[adamG]

No,it's not. So far this one I used https://robrobinette.com/5F6A_Modifications.htm ,which is Type 3, single pot 1MA.
I don't want to purchase dual gang pot 250K without being sure I does make sense.

Regards,

adam

[jojokeo]

I forgot to include the MV photo, please check again?

[adamG]

I forgot to include the MV photo, please check again?

Yes, that's the MV I used. That is why I mentioned MV and put it into my amp.In low amp's volume it sounds rather fuzzy. But it's ok when the pot is going up.
Actually, I can live with that ,but if other MV types got better, I'd apply one of them.

Regards,

adam

P.S."To steal ideas from one person is plagiarism. To steal from many is research." - the truth and funny;)

[jojokeo]

That MV is also called a cross-line MV type. It is fairly transparent as long as you don't have to turn it down too much and you can hear what happens when you do and why many find it not preferable.
What I said earlier regarding the pot(s) value was for this type below as it replaces the power tube's grid return resistance in the circuit and provides signal control which hits the tube's grids. Many find it better and as sluckey said earlier 250K should be fine but I wouldn't go any higher for fixed bias. I labeled the pot lugs for you.

[adamG]

What I said earlier regarding the pot(s) value was for this type below as it replaces the power tube's grid return resistance in the circuit and provides signal control which hits the tube's grids. Many find it better and as sluckey said earlier 250K should be fine but I wouldn't go any higher for fixed bias. I labeled the pot lugs for you.

Thank you very much.
Silly question. Bassman doesn't have power tubes' grid resistors and coupling caps are 0,1uF. So,may I implement cross-line MV with no fear?;)

Regards,

adam

[tubenit]

There is a difference between the PPIMV (LarMar) Master volume and the "typical" cross-line master volume.  The typical cross-line master volume is the worst sounding of any that I have tried and I don't recommend it.  I do like the PPIMV.

With respect, Tubenit

[adamG]

There is a difference between the PPIMV (LarMar) Master volume and the "typical" cross-line master volume.  The typical cross-line master volume is the worst sounding of any that I have tried and I don't recommend it.  I do like the PPIMV.

Actually, today I've ordered dual gang 250kA pots. Do you confirm the pot character "A" or should it be linear one?
May I address my question of grid resistor to you? There isn't such in Bassman.
Thank you.

Regards,

adam

[sluckey]

So,may I implement cross-line MV with no fear?;)

There's no danger in using the crossline MV, but I agree with tubenit about it being the worst mv I've ever used.

Do you confirm the pot character "A" or should it be linear one?

A linear pot will work, but I always use a log taper pot if it will be controlling the level of sound I will hear from the speaker.

May I address my question of grid resistor to you? There isn't such in Bassman.

Later Bassman models did have 1.5K grid stoppers. They're considered an improvement over the no grid stopper circuit. They are not necessary for the mv to operate.

[adamG]

There is a difference between the PPIMV (LarMar) Master volume and the "typical" cross-line master volume.  The typical cross-line master volume is the worst sounding of any that I have tried and I don't recommend it.  I do like the PPIMV.

Yesterday, I applied PPIMV(LarMar) type. The amp sounds really great. Vintage amp to my ears, of course. It's tempting to put its sound clips somewhere. When Iam ready with ,I'll do it.
Once more, I recomend Tweed Bassman together with Dumblish OD stage.

Regards,

adam

[tubenit]

Adam,




Glad you like the PPIMV!   I would love to hear your soundclips and hope it works out for you to post some.


With respect, Tubenit

[adamG]

Glad you like the PPIMV!   I would love to hear your soundclips and hope it works out for you to post some.

With respect, Tubenit

Thank you my friend. You've got a major share with this build. From now on, I'm gonna apply Dumblish OD stage to each of classic amp I'll build;)))

My best regards,

adam