things to make this pro reverb sound better. Ideas?

[sidehatch]

This will probably be my last pro reverb thread for a while. I've used it to learn .

My tech did things like black face it (its a 74 I think)

I've done the rest. I have speaker sI like- Emi's RW&B and weber G1265.

Besides the BF 'ing I added an Orange drop .05 bass cap, .022 sprague paper in oil mid cap and a 330 pf silver mica treble cap. I used a 48 pf silver mica for the bright which I love. The amp was suprislgly bassy-more so tahn any fender amp ive come across and thats why I change the tone stack.

I changed the two caps on the left side of the board with orange drop .05's as heisthl recommended. As far as the coupling cap Heisthl recommended a .003 but I couldnt find one. Tonight I tried 4 different caps and recorded each and they were all similar. I tried an orange drop .0047, and a .0022, a mallory .0047 and an orange drop .02 like Gerald weber likes. I thought it made the amp bigger and more scooped but used the orange drop .0047.

The only other mods I have done is I added a 5k linear pot where the polarity switch was that controls negative feedback.

What I have now is probably the best sounding Pro Reverb i've ever come accross and one of the top 5 fender combo's I've heard.

But still I know there are a lot of incredible amp guys on here(more than any other site) and thats are incredibly friendly.

If you guys see anything thats obvious that will make it sound better please let me know!! I have mostly NOS tubes-GE power tubes,and RCA preamp tubes and a RCA 5u4. I tried a GZ34 but it wont take one. It just blows fuses with it.

Thanks

[IMG:599:799]http://img.photobucket.com/albums/v334/ ... b/new1.jpg[/img]
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[IMG:599:799]http://img.photobucket.com/albums/v334/ ... rsuppy.jpg[/img]

[sidehatch]

Next will be a MM OT I think.

[Structo]

Now you have two threads on the same amp.

[C Moore]

Is it normal to have that many components on the bias board of a Pro Rev?

[Cygnus X1]

If it were me I wouldn't do much more to it at all.
Outside of the BF mod it should be just right.

I once started to noodle around with my 67 DR, doing this and that.

It's a drip edge SF that was 100% BF from day 1.

I restored everything back to spec, only left the NFB mod...and I refuse to do any mods on it again.
It is perfect!

[sidehatch]

Now you have two threads on the same amp.

I have 4 threads open on it. I wonder if I can combine them?

What happened is they got bumped up at different times . I was worried I was going to fry the amp yesterday so I started a new thread about that. Then I realaized guys were still talking on a way earlier thread.

Clutter central here. I dont mean to clutter up the board. If you know how to combine them I will or even delete them but I'd hate to do that if someone else got anything useful out of them.

Sorry about that.

[solderstain]

...and a RCA 5u4. I tried a GZ34 but it wont take one. It just blows fuses with it.

Don't bother with the GZ34 on a SF Pro. The PT for the SF Pro has higher secondary voltage than a BF version, and the GZ34 produces higher B+ than you want in a Pro. The 5U4 is the rectumfrier to use with a SF Pro (unless you change out the PT).

I second the comment about the OT. Get a Bassman-sized OT. The difference in tightness and bottom-end will surprise you. It's a great 'bang-for-the-buck' mod, and easy-easy-easy to do. I did it to my Pro as part of its conversion to a 'Bassman'. But I did the OT prior to revising much of anything else in the Pro's design. I wanted to hear the difference the OT made all by itself. It's worth the (relatively-little) time and expense.

[sidehatch]

Thanks!! I am ordering one this week.

Since I amp changing OT's do i still have to stay with the 5u4? You mentioned the power tranny controlling that.

Do you have the MM tranny in mind I should get or just call up MM and see what they say to get?


It seems to relatively easy from what I see on my amp. I just hope the wires are color coded or at least has conversion instructions.

After that just a bias is needed? I have gerald webers book and bias the way he suggests althought I have heard many people say thats not accurate. I just use a multimeter and read the current at the 2 resistors on the board and ground like he has a picture of in his book. He says bias it between 44 and 50 MA to where it sounds best. Is this right or way off?. I currently have GE 6l6's and its set at 49.1 ma. thats where it sounds best to me. I'll get a bias rite or probe soon but I figure as long as I have it where it sounds good and the tubes arent red and arc'ing I dont care how long the tubes last as long as it wont hurt anything else.

...and a RCA 5u4. I tried a GZ34 but it wont take one. It just blows fuses with it.

Don't bother with the GZ34 on a SF Pro. The PT for the SF Pro has higher secondary voltage than a BF version, and the GZ34 produces higher B+ than you want in a Pro. The 5U4 is the rectumfrier to use with a SF Pro (unless you change out the PT).

I second the comment about the OT. Get a Bassman-sized OT. The difference in tightness and bottom-end will surprise you. It's a great 'bang-for-the-buck' mod, and easy-easy-easy to do. I did it to my Pro as part of its conversion to a 'Bassman'. But I did the OT prior to revising much of anything else in the Pro's design. I wanted to hear the difference the OT made all by itself. It's worth the (relatively-little) time and expense.

[dave g]

Do you have the MM tranny in mind I should get or just call up MM and see what they say to get?

Bend over...

Try the Heyboer HY018343 or the HYOT45. Ted Weber has either for $68.

https://taweber.powweb.com/store/heyboer/hy_order.htm

If it were me though, if it sounds good then I would probably leave it as is.

[solderstain]

Thanks!! I am ordering one this week.

Since I amp changing OT's do i still have to stay with the 5u4? You mentioned the power tranny controlling that.

Do you have the MM tranny in mind I should get or just call up MM and see what they say to get?


It seems to relatively easy from what I see on my amp. I just hope the wires are color coded or at least has conversion instructions.

After that just a bias is needed? I have gerald webers book and bias the way he suggests althought I have heard many people say thats not accurate. I just use a multimeter and read the current at the 2 resistors on the board and ground like he has a picture of in his book. He says bias it between 44 and 50 MA to where it sounds best. Is this right or way off?. I currently have GE 6l6's and its set at 49.1 ma. thats where it sounds best to me. I'll get a bias rite or probe soon but I figure as long as I have it where it sounds good and the tubes arent red and arc'ing I dont care how long the tubes last as long as it wont hurt anything else.

First off, there's no reason to change rectifier tubes, and therefor no reason to change PTs, UNLESS you're going to do what I did. The 5U4 rectifier tube is perfectly compatible with the PT you have to produce the correct voltages. Leave it alone.

I changed mine because I made mine a 'dual-rectifier' option. Since I was converting mine to a hybrid Bassman circuit, I wanted to have the solid-state rectifier option that regular Bassmans have (stiff and punchy), and the option to switch to a tube rectifier for a squishier sound if I want that.

With the SF PT, the solid-state rectifier makes the B+ too high, because the SF PT has higher secondary AC voltage. So I switched to a PT that had lower secondary AC voltage. That let me have the solid-state rectifier option in the voltage range that a 'conventional' Bassman has, and then I use a GZ34 rectifier tube for the other option. The B+ voltages are within about 20vdc of each other. Good stuff. I could NOT have achieved that with the SF PT, so I changed it.

You? You don't sound like you're headed that way, so your existing PT is just fine. Don't spend money on something that you don't need to spend money on.

Now the OT? CHANGE THAT SUCKER! The PT? Leave it alone and live happily ever after with the 5U4 rectifier.

My $.02

[Firestorm]

I've always hated 5U4s -- just too "squishy for my taste -- so if you have money to burn, a new PT would let you run a GZ34 without the B+ voltage going up to the sky. But I also have annoyingly expensive opinions about GZ34s, like if it didn't come from Blackburn, it's just a waste of glass. So if you're really looking to get rid of serious money, my address is ... wait, I mean go ahead and spring for the PT and the Mullard. But as Solderstain points out, your PT is already "matched" for a a 5U4, so changing it out is basically unnecessary. You might try an Electro Harmonix 5U4, though. I've been very pleasantly surprised at how punchy and good sounding they are.

[sidehatch]

Im convinced on the 5u4.

They are readily avaible NOS for cheap and any GZ34 is close to of over $100.

Plus, I like a squishy feel.

Im really torn because the amp sounds great-not as good as the clean channel of my carr slant 6 but good as any fender I've heard.

More than anything, I'm learning to work on amps and I thought it would be a good project and I have yet to hear someone say the amp didn't sound better with a OT upgrade.

About the Heyboer: I have heard they are good too and they are half the price of a MM. Does anyone have any experience with both?

Last thing, About the bias method Gerald Weber talks about. Its here on page 168. I have the book and bias both of my fenders using this method. I have heard people say its not accurate at all. Is this good enough? I have it set at 49.1 ma with a RCA 5U4 and I experimented playing the amp and chose that because its between 44ma and 50 ma as he recommended. It was at 56ma when I got it back from the local tech.

http://books.google.com/books?id=fvUVBP ... t&resnum=9

[Firestorm]

The method (transformer shunt, right?) is plenty accurate. It's just that you can't set it to some arbitrary current number without knowing the plate voltage. If you multply the plate voltage by the current (in amps, so 49mA is .049 amps), you'll find the watts being dissipated by the plate at idle. You want to set it somewhere between 50% and 70% of the maximum plate watts dissipation shown on the tube's data sheet. As long as you're within that range, you can set it however it sounds best to you.

[Cygnus X1]

Im really torn because the amp sounds great-not as good as the clean channel of my carr slant 6 but good as any fender I've heard.

More than anything, I'm learning to work on amps and I thought it would be a good project and I have yet to hear someone say the amp didn't sound better with a OT upgrade.

Hey.
Just me again.

Why are you screwing around with a perfectly good amp?

Those early 70's silverfaces do, and will continue...to go up in value.
I suggest getting a different donor amp to play around with.

Sorry, I had to say it.

[sidehatch]

You do have a point. Im not doing any hack mods on it. No turning the normal channel into a gain machine using the vibrato tubes. Everything I've done is Justa tweak. Also this pro was pretty bad off when I got it. No holes or anythign but cosmetically it was shot and the faceplate was mangled up. I put a repro faceplate on it and put up the oxfords that sounded bad. I just figfure this is the amp to leaern on instead of my mint super reverb. I dont plan on selling this pro either. But I will heed your suggestions and not do anything that cant be easily reversed. If I do anything it will be add a MM tranny and put the original away.

Thanks