GlassMan Tube Amps update!

glassman

glassman

Electron Herder
I pop in here on occation but have busy building amps; I thought I might give an update on what's going on for those that are interested...

I battled an electrical interference issue in my shop that started mid-summer...in fact, I'm still battling it...the electric company is REALLY slow on digging into this project. I see the quality engineer every couple of weeks. He's done a lot of line recordings and a few sweeps of the area but still has no explanation for what we are seeing on the recordings. I've implimented some work arounds and can function somewhat normally now. This issue did set my amp launch back over two months from what I had planned.

The new amp has exceeded my expectations tonally. I have several playing out right now and all of the feedback is excellent. The most common responses (both from the guys playing out with them and those that try it in the local store its in) is that (1) they are astounded by the touch sensitivity of the amp and the dynamic range it has; you can go from clean to almost JCM800 dirty with picking dynamics alone. (2) They are surprised by how much the tone controls can shape the tone. Its only been in the store for a week and a half so I am still collecting responses.

Here's a sneak peek at the control panel...

View attachment 21956

The only complaint I have collected so far is from the guy that is recording my clips and plays out with it twice a week; he had to ditch his Carl Martin Plexi Tone pedal because the amp already did what the pedal was supposed to do. He replaced it with some sort of a clean boost.

I know all of this is meaningless without sound clips; please be patient, I'm at the end of my money right now but will have something to listen to soon.

I will post more pics if there is sufficient interest.

I'm off to the shop and will check back this evening!

Jerry
 
Re: GlassMan Tube Amps update!

Awesome update!

Thanks for keeping us updated.

I remember you telling me you could run a variety of power tubes in this design (please correct me if I'm wrong) --- what are you finding to be the best output tube - KTs?

Keep the pics a flowin'!

-Hunter
 
Re: GlassMan Tube Amps update!

ImmortalSix said:
I remember you telling me you could run a variety of power tubes in this design (please correct me if I'm wrong) --- what are you finding to be the best output tube - KTs?
Click to expand...

Hunter,

Yes you can run 6L6s, EL34s and 6550s as well as all of thier variants in the output. So far, new KT66s sound the best to me (and the guy doing my clips) but I loaded one up for a buyer with all old stock glass (Phillips 5881s) and the tone is to die for! The amp REALLY likes old glass...and it runs them in a way that they will literally last forever. The original prototype is now 15 years old and still has the cheap Chinese 6L6s that I originally put in it...they must have nearly 10,000 hours on them by now and they are still at 85%+ transconductance and full bandwidth! The "reactance" control on the "new" one compensates for loss in bandwidth so even the oldest tubes can have a happy home in this amp. I've even included a soft start for the rectifier tube.

Gotta run...got a customer meeting me at the shop. I will update with pics this evening!

Jerry
 
Re: GlassMan Tube Amps update!

drew_half_empty said:
what's that 2nd to last knob say?
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Reactance.

It adds gain to the output, widens bandwidth and has a fairly profound effect on how overdrive pedals interact with the amp. When the amp is at higher settings, it controls the transition from clean to dirty. At bedroom levels, it adds fullness to a clean tone.

It does a lot more than this actually but all of the other effects are guitar and playing style dependent.

It changes the way your guitar "feels" rather than how it sounds...if that makes sense!
 
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Re: GlassMan Tube Amps update!

what's the "on" button do?

I kid!

Looks cool. Reactance thing sounds sweet.
 
Re: GlassMan Tube Amps update!

That reactance knob sounds like a whole lot of fun to play with. These amps are exciting. Best of luck, dude.

EDIT: I know your avatar is just a lamp...but I still can't stop staring at it.
 
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Re: GlassMan Tube Amps update!

Nice looking amp based on the pic above anyways! I really dig the feature about making tubes last a long time. Would be SO nice to put some great tubes in an amp and then just forget all about tubes for a decade or more -- even with regular use of the amp.

Will definitely be keeping my eye out for additional info about this amp.
 
Re: GlassMan Tube Amps update!

ImmortalSix said:
Any ballpark for pricing yet?
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Yes. The in store price (at music stores) will be at $1950 initially. I will have special deals for forum members, however, you will need to contact me directly for this.

Lazarus1140 said:
How many Watts?
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Right around 25 watts depending on the rectifier tube used; 5U4s will yield right at 25 while a GZ34 will hit around 27. A 5Y3 will give you about 19 or 20 and is the only one that gives you any sort of compression. The amp has no problem keeping up in medium sized clubs, un-mic'd, with a relatively heavy handed drummer. Some of the clips that are in the works include live clips. I have plans to offer the Eminence ReignMaker (the British voiced one with an attenuator) as an option; I have to get one and qualify it first before that option becomes set in stone. On paper, it looks like a win though.
 
Re: GlassMan Tube Amps update!

I'm glad the reaction has been so positive. This seems like karma, because you have always been very informative in your posts, and from what I can tell, you're a very knowledgeable, easy-going guy. Congratulations.
 
Re: GlassMan Tube Amps update!

Ok.

Here are some pics of "The Truth" and a few comments on what you are seeing.

This is the front view of the amp (duh!). I am going for a classic look here without a lot of flash...I hate big logos...they just beg to be duct taped over!

(edit...ok...this isn't gonna work)


This is a three quarter view just to give you some perspective.

(edit...this one isn't gonna work either...I'll post these pics later though I will probably have to remove two of the others)

This is the rear view. The tube protector board is 3/4"...as in it actually protects tubes.
View attachment 21965

This is the rear view as it looks when changing out the tubes. The door at the upper left is where you adjust the bias (notice the test ports). The pilot light illuminates the screwdriver hole on the bias pot to make it easy to see in the dark. The tubes in the amp (stock configuration) are as follows: 5U4, (2)6L6GCs, 12AT7, 12AX7, 12AT7 and 12AX7, left to right. This is the most utilitatian setup and about as middle of the road for the amp as I can get; there are many shades of more or less aggressive available with tube substitution...something the owner can easily do him/herself. The speaker is an Eminence GB128; it's voiced like a Greenback but breaks up later than a GB normally would. I chose this speaker because nearly everyone knows what a Greenback sounds like and it's nice to have a known entity to start with when making a change. View attachment 21966

Just for kicks, I'm giving you a gut shot!
View attachment 21968

Here's what the board(s) looks like before it goes in a chassis. Yes, the tubes are board mounted; with 14 aluminum standoffs on that one board alone, it is plenty sturdy and offers a lot of benefits such as selective shielding ground points and the ability to swap tube retainer types (for the power tubes) without removing the chassis or even the main back panel. It also affords me to switch the entire preamp to octal tubes (6SN7s and 6SL7s) at a later time without a total design change.
View attachment 21969

Finally, this is a bottom view of a chassis with the iron attached. The chassis is 18GA galvanized steel. The transformers are made by Magnetic Components in Chicago; the power transformer is my own design. They are true paper wound transformers made the old way and have proven to be indestructable (at least in my torture tests). Before anyone makes assumptions based on the size of the iron you really ought to hear it for yourself...it's a mythbuster...that's all I can say.
View attachment 21970

Comments and questions are encouraged.

Jerry
 
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Re: GlassMan Tube Amps update!

I am both infotained and interested. Will visit thread regularly.
 
Re: GlassMan Tube Amps update!

Looks like serious quality in there, man. Very impressive and very, very cool.
 
Re: GlassMan Tube Amps update!

Looks really nice.

The description of your "Reactance" control has me intrigued. No, I won't ask you what the circuit is even though I want to...

With the option of multiple output tubes and/or rectifiers, do the test points include a point to measure power tube plate voltage? Sure would help someone who knows what they're doing to bias the amp right. I recently modified an external socket-type bias checker to include a separate output for plate voltage with a 1,000 to 1 voltage divider for safety reasons. Plate voltage shows in millivolts and using really big resistors in the voltage divider reduces the potential current/danger. Might not be safe for retail use though.

Are your boards PCB or eyelets with lots of under-board leads? Looks like PCB but it's hard to tell. If PCB, that's the way they should be made. Like the twisted heater leads off the board too.

Congratulations!

Chip
 
Re: GlassMan Tube Amps update!

Ok...here we go...front view of the amp. The cane grille is beer bottle proof!
View attachment 21974

And here's the promised 3/4 view..for proper perspective! By the way, it weighs around 40 lbs.
front view three quarter.jpg
 
Re: GlassMan Tube Amps update!

PVFan said:
needs a blue power light
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I stock blue jewels for the pilot lamp so you are in luck!

Fresh_Start said:
With the option of multiple output tubes and/or rectifiers, do the test points include a point to measure power tube plate voltage? Sure would help someone who knows what they're doing to bias the amp right. I recently modified an external socket-type bias checker to include a separate output for plate voltage with a 1,000 to 1 voltage divider for safety reasons. Plate voltage shows in millivolts and using really big resistors in the voltage divider reduces the potential current/danger. Might not be safe for retail use though.
Click to expand...

Excellent questions Chip! Actually, you don't need to know the plate voltage in the amp (I know...you are going WTF!?!?) The principle that this amp operates under is dramatically different than nearly anything out there. The power tubes fill to full bandwidth response at around 15mA and settings as low as 7mA are useful with no crossover distortion. Settings between 10mA and 22mA primarily change the bass and midrange character of the amp; its an excellent way to tune the amp to your tone. Settings above 22mA are possible; the amp can be safely biased clear into class A (around 95mA) but tube life will suffer, headroom will be reduced and there is very little change in character. The tubes will not red-plate at any bias setting. You can't use the 70% rule with this amp.

I'm not a student of convention...this amp is a byproduct of my mindset. I designed it to be highly adjustable simply by replacing tubes, the speaker, the reverb tank; basically anything external...and safe, so the tweakers out there can dial in thier tone without modding the circuit.

Fresh_Start said:
Are your boards PCB or eyelets with lots of under-board leads? Looks like PCB but it's hard to tell. If PCB, that's the way they should be made. Like the twisted heater leads off the board too.
Click to expand...

The board is an eyelet board (that I make in my shop) on 1/8" glass epoxy board. The wires are on the back side and I have templated the wiring pattern to enforce repeatability. I couldn't make this amp with a PC board. The wire routing is too important to the behaviour of the amp and I couldn't replicate that on a single plane like a PC board (I tried by the way...it lost that X factor).
 
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