59 bassman 5F6A build

[bluesfendermanblues]

Maybe it's just a "feel" issue. Not sure. Give it a listen.

http://youtu.be/BJOw_ewpTco

DON'T CHANGE ANYTHING!!

My humble advise, since it already sounds absolytely great, don't tinker anymore with the amp. Use it as is, it never gets better than this.

You got a great full blues tone.

What speakers do you have in that cabinet?

[Delmar Evans]

Thanks for the advice. So, I just went through and checked all voltages on my blueprint. All voltages good. I plugged in my Les Paul. Left all settings the same. I think that the single coil pickups are what is putting me off. The Lester sounds great! Im not gonna mess with anything. I think I was fighting a "feel" issue with the strat. I don't play it much and it does not respond to my playing style as I am used to a Humbucker short scale guitar. With that said, Ill do a Lester video and post it. This amp rocks !

[Delmar Evans]

Oh, forgot to mention speakers. I initially was using my SR cabinet with 4 10 inch Fender alnicos in it. 1970 vintage or so Then I rewired my other 4 10 cabinet to 2 ohms. This cabinet has 2 ceramic and two alnicos in it. I have no idea what kind of speakers any of them are! That is the cabinet in the video

[Delmar Evans]

Thanks to all who chimed in on this one. Well maybe I was over thinking how the tweed should sound. Last clip with les Paul. Zowie is all I can say. Give it a listen. https://youtu.be/fScmLT6ytXE

[strelok]

Glad that's all it turned out to be! It sounds great with the Les Paul. I realized after I posted that probably most of the Bassmans I've heard had a 12ax7 in the first preamp slot so that's why I was expecting a bit more breakup. It sounds awesome though. Its cool to hear it with the preamp tubes it was designed for. I always thought it was odd that the tweed bassman brokeup around 3-5 on the volume knob despite the fact that fender designed it to be clean. But now I realize (and feel a bit silly that it never occured to me before) that with the 12ay7 in the first slot it stays clean most of the way up the control.

[Delmar Evans]

Back on the bassman with a few more questions. Amp sounds great! I set it up with some nos Russian tubes. All voltages were spot on. Came across nos tungsol 5881's and an RCA GZ34. So I put them in. Plates went from roughly 430 to 480. I know that the GZ 34 does not drop that much voltage. So I installed the Russian GZ back in. Plates back to 430. Do I have a questionable RCA rectifier tube or just a weak Russion Rectifier tube ? I'm thinking those nos 5881 tungsol a won't hold up. Biased those at 35ma. Any thoughts appreciated.

Regards

Mark

[Leo_Gnardo]

just a weak Russian Rectifier tube ? I'm thinking those nos 5881 tungsol a won't hold up. Biased those at 35ma.

Weak Russian rectifier sounds about right. OTOH some Russian tubes sold as 5Y3 act more like GZ34, can't they get anything right? You're wise to monitor what your tubes are doing, and not make assumptions based on the labels applied to sell them.

TungSol 5881, when they were new new stock late 50's - early 60's, held up fine in Tweed Bassman & Brown Supers & similar with B+ approaching 500V. There's no harm in saving yours for less strenuous application though.

[Delmar Evans]

Thanks ! I'm wasn't comfortable with the 480 Vdc on the plates. No red plating or any issues. Sounds great, but I find that the amp has a nicer break up at the lower voltage. The 5881's are, in fact, nos from 1960 or so. The Russians I believe are Nationals and are NOS from the 60's. Was going to add a couple of center tap diodes or change the rectifier to a 5V4 or a 5R4 or maybe a 5U4 I know the transformer can handle the current draw of 3 amps

Any thoughts appreciated

Regards

Mark

[ToneMerc]

Thanks ! I'm wasn't comfortable with the 480 Vdc on the plates. No red plating or any issues. Sounds great, but I find that the amp has a nicer break up at the lower voltage. The 5881's are, in fact, nos from 1960 or so. The Russians I believe are Nationals and are NOS from the 60's. Was going to add a couple of center tap diodes or change the rectifier to a 5V4 or a 5R4 or maybe a 5U4 I know the transformer can handle the current draw of 3 amps

Any thoughts appreciated

Regards

Mark

480V with USA glass is kind of high, you must be using BF Bassman power iron?

Here's one I did with NOS 5881's

http://ampgarage.com/forum/viewtopic.php?t=20899

TM

[Delmar Evans]

Using MM Tone Clone FTBP 59. Power with a MMF050BM-2 output and a FC 2.84 choke.

I'm thinking of calling MM about the spec on this transformer. I want 400 on the plates.

Regards

Mark

[Delmar Evans]

Do you remember what your unloaded voltages were on your Heyboer? MM transformer is 380-0-380. I'm thinking of changing out to a 350-0-350 or a 330-0-330.

[ToneMerc]

Do you remember what your unloaded voltages were on your Heyboer? MM transformer is 380-0-380. I'm thinking of changing out to a 350-0-350 or a 330-0-330.

As built in 2013:

Pri: 124.5 VAC
Unloaded DC at 5AR4: 479.8 VDC, 698 VAC at pins 4 & 6
Filament voltage at V1: 6.87 VAC

(698/2 = 349 VAC unloaded)

V4 & V5 Tung-Sol 5881 : 436 VDC plates, 434 VDC screens
Voltage at 220K junction: -48.4, at cathodes, V4: -30.4, V5: -34.8

However, IIRC that PT was wound for a 123V primary and it had the correct range HT rating so that it would load down to around 430V or so with modern mains voltages.

In 2014 a sub station was added close to my home and now mains voltage hovers around 122.4/5 VAC year round. I would imagine if I opened it up, the plate voltages should be several volts lower.

TM

[Delmar Evans]

Thanks for the info. So a 350-0-350
Should work

Regards

Mark

[ToneMerc]

Thanks for the info. So a 350-0-350
Should work

Regards

Mark

If you want 400 on the plates you will need something lower than 350. Personally, 330 would be my first choice.


TM

[Delmar Evans]

Yep I agree. 330-0-330 with a gz34