Ask Myles or Chad - amp or live playing questions

[myles]

The MAZ is long overdue for an output tube change.  300 hours is pushing it.

[Surreal McCoy]

So buy a match quad set of el84 tubes [EH I presume] and simply swap them out? It's a cathode biased amp, i think.... Do I need to swap the rectifier &/or pre-amp tubes as well?

Many thanks,

-Tim

[Surreal McCoy]

Starting to order tubes now - what's the difference between EH EL84 in a soft, medium or hard quartet??

[Surreal McCoy]

what is with these smiley faces. I can't keep them out of my posts.........

"Starting to order tubes now......"

[myles]

You want a matched quad that meets specs. No hard or soft nonsense. You want tubes that meet design spec.

Go to ....

www.kcanostubes.com
www.dougstubes.com

I trust those folks. There are others but I have used them for years.

No reason to swap preamp tubes unless there is a problem such as microphonics or you want better tone.

The rectifier ... they are either good or bad.  They do not wear out, they just fail.  Always have a spare on hand.

[Surreal McCoy]

New "live playing Q".

I found a nice 1 x 12 cabinet for my Carmen ghia. It has an 8 ohm Emi tonker in it. But there is just a single 1/4 inch jack in the back. I'm picking up the twin to this cab tomorrow - Emi tonker, 1x12, single jack in the back.

If I want to run both cabs, how do I jumper them when they don't have the two 1/4 inch jacks in the back........

[hangs head in shame b/c he doesn't understand basic amp rigging........]

[myles]

You need a simple parallel Y adaptor, male on the amp side splitting to two female 1/4" plugs. Plug into the 4 ohm jack on your Carmen Ghia. Plug speaker cables to each of the female jacks on the adaptor and run speaker cables to each 8 ohm cabinet.

Just like this one .... www.musiciansfriend.com/accessories/monster-cable-mono-male-to-2-female-1-4-y-adapter

Many folks make these and many may be less expensive. This is just one example.

[heynewguy (Ol’ Bill)]

Our Z brother pcns (Todd) also sells these on his website.

www.procablesnsound.com

Discount for forum members. 

[myles]

Oct 12, 2013 10:36:54 GMT -7 heynewguy (Ol’ Bill) said:

Our Z brother pcns (Todd) also sells these on his website.

www.procablesnsound.com

Discount for forum members. 

There you go.  Always give business to Z Forumites!  

[Matt]

Hi Myles!

I really like the how my SRZ-65 sounds with stock tubes(though it can be a bit bright/harsh on the high end if I don't reduce the treble and presence).

What NOS preamp and rectifier tube(s) would you recommend as direct replacements for a SRZ-65?

What would you recommend diffrently if I want to tame the extreme high end?

Not sure it matters, but I like very little sag in my amp but not sure I want to go the solid state rectifier route given the brightness of the amp as it currently stands.

Thanks in advance!

[myles]

Nov 5, 2013 18:09:58 GMT -7 Matt said:

Hi Myles!

I really like the how my SRZ-65 sounds with stock tubes(though it can be a bit bright/harsh on the high end if I don't reduce the treble and presence).

What NOS preamp and rectifier tube(s) would you recommend as direct replacements for a SRZ-65?

What would you recommend diffrently if I want to tame the extreme high end?

Not sure it matters, but I like very little sag in my amp but not sure I want to go the solid state rectifier route given the brightness of the amp as it currently stands.

Thanks in advance!

Try a solid state rectifier for less sag.  One of Carl Verheyen's SRZ-65s is set up with a solid state and the other with a vacuum tube rectifier.  

Where is your bias set?  Too cold and the amp is grainy, too high and it will be harsh.  If you send me your B+ voltage I will make a recommendation.

What preamp tubes are in the amp now.  It is easier for me to give you a few thoughts if I know what you have that you don't like as much as you might.

[Matt]

I just acquired the amp which is a used 2011 edition. Unsure of the bias and have don't have equipment to get that info for you unfortunately.

The amp has the stock preamp and rectifiers tubes: V1: JJ ECC83S, V2: Tung Sol 12AX7, V3: Sovtek 12AX7LPS, V4/5: Mullard (Reissues)EL34 (matched pair), V6: JJ GZ34

I do have an NOS RFT that I thought about trying in V1. I also have a coulpe NOS JAN GE 7025 that I could use as well as a NOS JAN Philips 5AR4.

[myles]

Nov 6, 2013 16:56:57 GMT -7 Matt said:

I just acquired the amp which is a used 2011 edition. Unsure of the bias and have don't have equipment to get that info for you unfortunately.

The amp has the stock preamp and rectifiers tubes: V1: JJ ECC83S, V2: Tung Sol 12AX7, V3: Sovtek 12AX7LPS, V4/5: Mullard (Reissues)EL34 (matched pair), V6: JJ GZ34

I do have an NOS RFT that I thought about trying in V1. I also have a coulpe NOS JAN GE 7025 that I could use as well as a NOS JAN Philips 5AR4.

Matt,

You need to get the bias checked.  It is fast and easy via a tech if you do not have the tools or experience.  If you are ever in my area I would be happy to check and adjust if necessary at no charge.

The stock tubes are OK but that ECC83S in V1 is harsh, grainy and compresses too fast.  It is edgy, not vintage sounding.  If I had to change one thing in the amp pronto it would be to toss that ECC83S.

The RFT and GE 7025s would be amazing in V1 and V2.  Both great.  In the end it will be your personal taste as you cannot go wrong.  The 7025 in V1 may be a bit more pedal friendly if a pedal has a very high output level.  The LPS in V3 is great but if you might want to try one of those 7025s there as well as they will have proper current to push the output tubes where the Sovtek LPS may be lower than desired.

The JJ rectifier is fine but the NOS JAN would be nicer.  Keep the JJ as a backup perhaps?  Leaving the JJ in there though is just fine.

Those Mullard reissues .... one more reason to check the bias.  I'd also want to check the tubes.  They are typically quite weak.  Normal plate current output of an EL34 is 100mA at 265/250/-13.5.  These are typically around 80mA, about 20% down and will compromise your clean headroom and tone in general.

Hope this helped.  Post your results and thoughts when you change things.

[Matt]

I was planning on taking it to a local tech to have the tubes checked, place the power tubes if necessary and bias accordingly. (I'd love to take you up on your offer of I ever get out your way a - thank you very much for the offer!)

What should I tell the tech in terms of how to bias this specific amp? Is there a number that it should be biased to?

[Deleted]

Matt - With all due respect. If your tech doesn't know where to bias the amp, you need a new tech. The trick is biasing the amp to where YOU will like it. Some folks like to run their tubes a little cooler or maybe a little hotter than other folks do. Hopefully your tech will work with you to find your sweet spot.

Here is what DRZ recommends: SRZ 65 34 mA.

[Matt]

Thanks so much for the help!

[myles]

doc001 makes a very valid point. There is a range which depends on plate voltage and this range can run anywhere from 30% to 70% of idle dissipation. Most folks prefer something in the 50%-60% range but it really is personal preference and a good tech will generally put things in the 50-60 range.

Ask him where he normally would bias your amp. If he does not have answers or talk about plate voltage and tube type being factors or come up with a number around 36-38mA post something here and some of us may have something to say.

[Matt]

I put in the RFT (V1) and 7025 (V2) along with an ANOS GE 12AX7 long plate in the PI (V3) and it made a definite improvement in taking the edge off of the amp. Seemed to add some clarity and definition more than anything.

I still need to take the amp in to a tech to check the bias but I was thinking about just replacing the power tubes if the Mullard reissues just are up to snuff. Need to find a trustworthy tech first.

Myles - what power tubes do you recommend in the SRZ65? Since you have such extensive experience with the model of amp I'd love you input. I have the original Groove Tubes that came in the amp as well as a pair of JJs.

Thanks again for all your advice!

[myles]

Nov 10, 2013 19:06:39 GMT -7 Matt said:

I put in the RFT (V1) and 7025 (V2) along with an ANOS GE 12AX7 long plate in the PI (V3) and it made a definite improvement in taking the edge off of the amp. Seemed to add some clarity and definition more than anything.

I still need to take the amp in to a tech to check the bias but I was thinking about just replacing the power tubes if the Mullard reissues just are up to snuff. Need to find a trustworthy tech first.

Myles - what power tubes do you recommend in the SRZ65? Since you have such extensive experience with the model of amp I'd love you input. I have the original Groove Tubes that came in the amp as well as a pair of JJs.

Thanks again for all your advice!

Tubes are really a matter of personal taste and preference.  I find the JJs too edgy and gritty for my taste but lots of folks love them.  

I am not very happy with any of the current production EL34 tubes.  They are all weak compared to spec, the traces are not smooth and linear (buried somewhere on my GAB website there are traces), and they have short life.  Well .... with one exception, a real =C= winged C Svetlana EL34.

Mike over at KCA has some on sale - www.kcanostubes.com/content/sed-winged-c-el34-singles-pairs-quartets-sale-price

The Ruby EL34B and STR are better than other production EL34s and are a good option.

ANY NOS is better than any production.  Siemens are vintage sounding and really nice.  Mullards (real ones) are expensive but considered the finest by most folks.

These are loved by a lot of folks too - www.kcanostubes.com/content/nos-tesla-el34-singlespairs-not-jj

There are some other fine choices here - www.kcanostubes.com/catalog/19

In the end it is a matter of personal taste but any of the above would be preferred by me over the stock JJ tube and I would not use any current production tube with vintage names like "Mullard", "Svetlana" (by Sovtek), "Gold Lion, EH etc. where the names were purchased by Reflektor and are now stuck on ho hum, low power, short life lackluster sounding tubes.   Again .... my personal taste and observation.

[ThemBones]

I am new to Cabinets. Is a 3/4" cabinet necessary for the best sound?
I play mostly P & W at a smaller church with my M12. The volume never gets past noon and the amp is mic'ed up.
Would a 1/2" plywood cabinet (such as a commonly available egnater tweaker cabinet) suffice?

[myles]

Nov 12, 2013 12:27:46 GMT -7 ThemBones said:

I am new to Cabinets. Is a 3/4" cabinet necessary for the best sound?
I play mostly P & W at a smaller church with my M12. The volume never gets past noon and the amp is mic'ed up.
Would a 1/2" plywood cabinet (such as a commonly available egnater tweaker cabinet) suffice?

Sorry, I cannot help you here.  I am not a cab guy and there are many factors.  It is part art and part science and economics are a very important factor.  Cheap materials and construction and you will end up with something that is better for firewood than sound.

I'd talk to some cab folks.  Jeff Earl at www.jdesigncabs.com/ is very knowledgeable.  I'd also talk to some of the Z folks here, perhaps some will chime in.

[ThemBones]

Fair enough, thank you sir.

[mickey]

Hi Myles, I've always been under the impression that all you need in V3 and V4, reverb driver and return, are working tubes, and they don't have to be anything special. I recently had some annoying crackling going on with the reverb in my Maz Sr head, and a couple of times the reverb stopped working. After removing the tank, checking it over and making sure the connections were all OK, I reinstalled it and changed V3 from a Chinese 12AT7 to an old Jan Phillips 12AT7 which I just happened to have already, and V4 from a Svetlana 12AX7 to a 12AX7EH which I also had lying around. The reverb sounds fine now, and actually seems to sound smoother than before. I thought the driver was just that, a driver for the reverb pan, but could it also make that improvement, or is it just down to me improving the connections, or am I hearing things? Thanks!

[myles]

I never use substandard tubes in any amp position.

On reverb tanks, keep connections clean just as you would an input jack, speaker jack, etc.

Side note ... the Svetlana 12AX7 is one of the worst on the market when it comes to noise and sub standard performance.  It is very unreliable and inconsistent.

[mickey]

Thanks Myles.... just so I'm clear, can the quality of the tube in V3 or V4 have a bearing on the actual quality of the reverb, or is it that the reverb pan just needs working tubes to function at its best?

[myles]

The tube makes a difference.

[mickey]

Thanks Myles, so hopefully I'm not hearing things which aren't there!

[BradPaisleyFan (Pat)]

Hey Myles,

I am looking at getting replacement tubes for a Z Wreck which Doc has clarified he runs 6n14n tubes in. When looking online for these, I have no luck finding them but I do run across the 6p14p tubes which seem very affordable. Any idea if these tubes are the same or a very close substitute for each other?

Also, I have a vox ac4 practice amp with 2 12ax7's and 1 el84. I was thinking of replacing one of the ax7 for a 5751 to cut back some gain...and guessing that I would do that in v2 right? Also, what would be a good tube to run in the el84 section for this particular amp for a bigger sound while staying relatively clean overall?

Your help and knowledge is appreciated!

[myles]

The 6P14P is a Russian designation for an EL84 replacement.

The 6N14N is a bit different. This will give you some more info: www.ax84.com/bbs/dm.php?thread=84622

On the 5751 ... it is personal choice. Try it.

[Matt]

Hi Myles,

Looking for advice on options to increase the clean headroom for my SRZ-65. I love the natural tube distortion but I was wanting to get a bit more headroom before that breakup kicks in. I've tried NOS JAN 5751's in V1 and V2 and didn't do much to help (currently running NOS JAN 7025's in there now). I keep the master volume pretty low so not sure if a change in power tubes would help the headroom at all (currently running Mullard re-issues in there until I can find some reasonably priced NOS tubes).

Any advice or is the amp just a gain machine with early breakup regardless?

Thanks in advance!