Feel free to ask Myles

[Zephyr]

Guess I'll just have to assume that it's really a 5751 then, eh?

[myles_rose]

I don't want to assume anything but a safe assumption with the odds in your favor are ....

 

If it is an NOS 5751 it is probably a real 5751. If it is a new production 5751 it us surely NOT a 5751 regardless of the gain reading on any tester, it is nothing more than an out of spec 12AX7 reject. It will not pass any of the vibration criteria tests or other tests a real 5751 had to pass in the past.

 

[Zephyr]

Thanks for the info Myles, all seems to be as it should; just seemed to be a little suspicious to me.

[myles_rose]

I went back and looked at some of your earlier posts....

 

JAN 5751 ... NOS and a good tube

 

Tube Depot .... good folks, good stuff, good prices and they know what they are doing.

 

Their tester, the VTV unit, would be a minor factor behind the other two factors and 95 would not be the true gain at all. A lot of 12AX7s read 105-120 on that tester and most production 12AX7s have a true gain of 80-90 today on average so things make sense.

 

Your 5751 is a real one and you probably have a nice tube there.

 

[Caevan O’Shite]

Very interesting little sub-thread here on Zephyr's NOS 5751! Thanks, Myles! Thanks, Zephyr!

[Zephyr]

A bit of a follow up here, but I found out today that it is VERY microphonic when used in amps that have a high gain stage for V1.

 

Where's a good place to put a microphonic tube in a Deluxe Reverb? I was thinking V4 might work...

 

 

[myles_rose]

Get rid of microphonic tubes. They only get worse. In a DR I personally think all the 12AX7 spots are important.

[A String]

I had a quick question for you Myles. My old Traynor amp (1969 YSR-1 Custom Reverb), has two plugs in the back for foot pedals. One for the reverb and one for the tremelo. I thought, rather than trying to find foot switches, I may just make them. Is there any reason to think that the switches would be anything other then a "temporary click" style, where the two wires temporarily make contact and then the effect is activated/deactivated, or is there a chance that the two wires remain in contact for on and come apart for off (if it's even ever been done that way)?

[myles_rose]

Craig,

 

A standard footswitch should work fine and folks have wired up temporary shorting jacks as well. Antique Electric Supply has inexpensive ones that work well.

[A String]

Great! Thanks Myles!

 

Oh, and keep those Facebook pics coming. It's a very cool thing to have a window into life out there. I'm quite enjoying them!

[myles_rose]

Pix are usually uploaded most times I am out and about.

[Electric Biscuit]

Hi Myles,

 

I notice with my Mesa/Boogie F-50 widebody combo, the tones only sound good when heard from a fairly steep angle - that is, either above or to the side of the amp. Directly in front, it sounds very harsh, bright and "stabby" if that makes sense.

 

It sounds fine if I throw, say, a blanket or sweater over the amp.

 

Is this likely related to the speaker? It has a Mesa Black Shadow 12". If I swap that for something else, could it potentially make a positive difference?

 

I've tried using and external EQ to see if that helps, and it doesn't make a significant difference.

 

Thanks,

Colin

[Caevan O’Shite]

Electric Biscuit- if I may barge in here- some cabs and speakers can be very "beamy", very directional, and the harsher, strident highs and transients coming from the center of the cone can be exacerbated.

 

Since you've already found that physically damping and blocking the central "beam" coming out front and center from the speaker to be helpful here, you might want to try something like the Weber Beam Blocker mounted behind the grille-cloth, or even just some gaffer's tape stuck on the grille-cloth over the center of the speaker and its dust-cap.

 

http://2.bp.blogspot.com/_BAeRbNCxj2o/R-_EV8IxJcI/AAAAAAAAAAc/qO-F9VzSToc/s400/beam_blockersL.jpghttp://www.boogieauctions.com/wp-content/uploads/2009/10/-70852704658615860.jpg

[myles_rose]

Hi Myles,

 

I notice with my Mesa/Boogie F-50 widebody combo, the tones only sound good when heard from a fairly steep angle - that is, either above or to the side of the amp. Directly in front, it sounds very harsh, bright and "stabby" if that makes sense.

 

It sounds fine if I throw, say, a blanket or sweater over the amp.

 

Is this likely related to the speaker? It has a Mesa Black Shadow 12". If I swap that for something else, could it potentially make a positive difference?

 

I've tried using and external EQ to see if that helps, and it doesn't make a significant difference.

 

Thanks,

Colin

 

Speaker and cab related .... the Beam Blocker is a great suggestion!

[myles_rose]

Electric Biscuit- if I may barge in here- some cabs and speakers can be very "beamy", very directional, and the harsher, strident highs and transients coming from the center of the cone can be exacerbated.

 

Since you've already found that physically damping and blocking the central "beam" coming out front and center from the speaker to be helpful here, you might want to try something like the Weber Beam Blocker mounted behind the grille-cloth, or even just some gaffer's tape stuck on the grille-cloth over the center of the speaker and its dust-cap.

 

http://2.bp.blogspot.com/_BAeRbNCxj2o/R-_EV8IxJcI/AAAAAAAAAAc/qO-F9VzSToc/s400/beam_blockersL.jpghttp://www.boogieauctions.com/wp-content/uploads/2009/10/-70852704658615860.jpg

 

Outstanding suggestion

[Electric Biscuit]

As to the other part of my question, would it likely help, though, if I wanted to invest in a nice Celestion or something?

[myles_rose]

Your Mesa Black Shadow is just a high wattage Celestion. You cannot use a lower powered version and to my ears those are the sweeter sounding versions .... H30, Vox Blue, etc. A V30 could work but in the end speakers are personal choice.

[Caevan O’Shite]

What about a Celestion AlNiCo "Gold", Myles? Would that- or wouldn't it- possibly apply here?

[myles_rose]

It would apply tonally ... the Gold, although only a 50 watt speaker so in a 1x12 combo you could run into prolems at higher settings.

[Electric Biscuit]

It's only a 50 watt combo though

 

I could maybe go for a G12K-100

 

 

What I'm looking for, tonally, is something warmer and darker than most people prefer. I like it a little "loose" sounding too, instead of the typical rock tight midrange crunch that everyone seems to want. Any recommendations? Doesn't have to be Celestion

 

[myles_rose]

The Gold would be fine if the 50 watter and not the 100 watter. The K100 is not a very versitile speaker, I have one myself and it is not used often. There are many Weber models that would work great but again, speakers are personal taste.

[myles_rose]

Just hoping all of you had a great 4th of July.

[Caevan O’Shite]

Yhup! Thanks! Hope you did, too, Myles!

[myles_rose]

Was a fun one for me. Spent the day with my two boys.

[ThatBookGuy]

Hello,

 

I have just acquired a mid to late-1950's Supro combo amplifer, most likely a Spectator model, and have every hope of making it into a usable amplifier. If not for the stage, then as a studio tool.

 

The tubes look very clean and probably original, although I'm going to take them to my locally-owned electronics store to have them tested. The speaker has serial codes that match several years from the 50's models.

 

Has this been covered in the mag (couldn't find anything in the search)? I don't necessarily want to restore to original condition, just make safe and playable, and clean. There was a wasp nest inside! Could you recommend some resources? I would like to keep any removed parts for the sake of vintage, but realize that it probably needs a grounded plug and other safety precautions. I would appreciate any information you might offer. Thank you for your time.

 

 

[myles_rose]

Look for a good tech in your area and have him go over the amp. There are many caps that are probably dried out and need replacement. You cannot reliably test output tubes in an old store tube tester, they do not develop sufficient voltages and give readings that are worthless. Have them tested by a tube vendor, a good one. Those are the first steps. The old Supro stuff is terrific.

[ThatBookGuy]

Any recommendations for a good tech in the St. Louis, MO area? Thanks, Myles!

[myles_rose]

I'd post the question for a good tech in the Mo area on the main board. Or .... send an email to dan@65amps.com as he has family in Columbia and was born and raised there - maybe has some ideas.

[Psycho-Spud]

Hi Miles. Not quite an amp question, but... I'd like to do a mod to my guitar. I'm just -no- good at running the volume knobs up and down for lead breaks. I use the neck PU. for leads and neck PU. for rhythm, with the volumes ajusted to suit and use the pickup select switch to change. This just doesn't work very well.

I'd like to find a volume pot with a switch that toggles back and forth with a push. This would bypass the pot for full on volume.

I know there are units that do this with a push/pull, but that's still to complicated for this thumbfingered lout:-) I know the push/push feature can be done because I've seen it in other electronic items. I've looked around on the web for such a beastie with no success. Have you (or anyone else reading this) heard of a manufacturer who makes these?

[myles_rose]

Check www.tubesandmore.com as just one of many places to get parts. There are many other places as well.