DeArmond Amps (Moved)

[Structo]

I had this in Gary's (Glasman) thread about his single ended guitar amp but decided I didn't want to hijack his thread so I moved it here.
These amps have been selling for stupid money.

Some DeArmonds sell for upwards of $7,000!

But more often around $2K-$3K depending on model and condition.
Crazy!

Check out this Dearmond R15T this guy found at an estate sale.
Looks brand new!

Amazingly they were getting $3K-$4K for these amps at their peak value.

[IMG768]http://i714.photobucket.com/albums/ww14 ... ond014.jpg[/img]
[IMG768]http://i714.photobucket.com/albums/ww14 ... ond004.jpg[/img]
[IMG768]http://i714.photobucket.com/albums/ww14 ... 5T/008.jpg[/img]
[IMG768]http://i714.photobucket.com/albums/ww14 ... 5T/006.jpg[/img]

Looks like it has one of those potted R/C networks.

Anyway, here is the schematic I think is the R5T

The R5T amp was a single 6V6 SE amp.


As for some trivia, Rowe Industries, Toledo, Ohio, USA made the Dearmond amps back in the day.

They also made C. F. Martin branded guitar amps for a while which were DeArmond amps but with the Martin logo and different tolex and grill cloth.

They looked pretty cool for the day I think.

[img:307:268]http://www.musicpickups.com/images/15575314_yd1h.png[/img]
[img:488:262]http://www.musicpickups.com/images/15575315_cf2b.png[/img]
[img:617:444]http://www.musicpickups.com/images/16049261_4dfn.png[/img]



I think this is a schematic for the DeArmond SE RT5 amp.
Any idea for the blotted out components?

[David Root]

That R15-T is dead mint! If it weren't for those red gooped boards I would have said it could be a fake.

[selloutrr]

something like this I have all but one part. a 2 watt resistor

[tictac]

Better?

[karl82]

Hey, that's my schematic!

It's a scan of an original copy that I posted to the web years ago.
Thank's Tictac for cleaning it up.
Wish I saw this post sooner so I could have been of some assistance.

BTW... I own a Dearmond R5T, picked it up at a yard sale about 10 years ago. Definitely a sweet little amp. The original Jensen P10T speaker honestly isn't the best. The standard series Jensen speakers never were that great. There's no rub or anything, the speaker is in perfect condition. It's just that it breaks up extremely quick and the sound is just lacking. I've tried a Weber in it and the improvement was night and day. When I got it the tremolo didn't work. I discovered that the film caps in the trem circuit were bad so I replaced them with NOS Cornell Dubilier ones identical to the green one seen in the first post and that did the trick. The original caps were Pyramid brand and I'm pretty sure the NOS Cornell's have an identical molded plastic construction. It's prob my favorite tremolo sound ever. The circuit is a little different than what is found in a Vibro Champ and I much prefer it. In the past I've thought about building replicas to sell just because I love it so much. This thread fired up my interest again so I may just build one soon, cab and all, to test the waters.

[frontbum]

Anyone have the schematic for the r15t?

[MikeHutchison]

Sorry for re-animating an old thread, but I just picked up a DeArmond R5 at a yard sale. Picture attached.

It's in fantastic condition - was covered it's whole life and looks rarely played. Original instruction sheet and hang tag were inside the amp, spare fuse from the factory still stapled to the bottom. Mint mint mint. I can put up a scan of the schematic from the instruction page if anyone would like.

I turned it on just long enought for the tubes to warm up. Nothing but a loud buzz. I'm sure it needs recapped at a minimum.

I'd love to hear some opinions on how to go about bringing it up to working condition while maintaining its collector value. For ex... would rebuilding the whole amp with modern close tolerance resistors and orange drop caps be a bad thing?

I plan to keep it, but would love to hear estimates of it's value too.

[Structo]

Wow that is clean!

I would love to see some gut shots.

So yours is just an R5? No tremolo?

Most likely the electrolytic caps need replaced.

But it may also have a bad rectifier tube or power tube.

Does yours have the large three-section cap can?

See if you can find a compatible cap here, make sure the voltage is at least 450vdc

If it is a 40uF, 15uF and 10uF cap, you can use a 40uF, 20uF, 20uF, 20uF and parallel the last two 20uF for a total of 10uF.

But matching the diameter of the existing cap may or may not be a problem.

See if you can find a compatible cap here, make sure the voltage is at least 450vdc

http://www.tubesandmore.com/products/mu ... ecommended


Then the 25uF 25v cathode bypass cap on V1 and the 25uF 25v cathode bias cap on the 6V6 power tube should also be replaced.

Depending on your wall voltage, since this amp is designed for 115vac operation, if your wall runs 120+ vac then it could up the heater voltage and plate voltages a bit too much.

Many guys use variac's to operate vintage amps.

Check out this article on vintage ac power for amps.

http://www.geofex.com/Article_Folders/v ... ntvolt.htm

Hope this helps.

[MikeHutchison]

Hi Tom,

Thanks for the reply. Let me clarify where I'm coming from here. The amps I've worked on in the past have been Hammond organ and Leslie speaker amps. Safety and function typically prevail over collectibility in that world. At a minimum, the following is usually done automatically:

1) New axial electrolytics, leaving the can in place (disconnected) for looks
2) New coupling capacitors
3) New plate resistors

I also was planning on installing a new 3-prong cord, properly grounding the chassis, cutting out the 'death cap', and switching the fuse to the hot side before the switch, which are all pretty standard safety measures.

Reasons not to?

Thanks. I'll be taking inside shots tonight and will be sure to post 'em up here (honestly I doubt the back has ever been off this thing).

Oh and that vintage AC article is worth the price of admission! Great trick.

[Structo]

OK I understand better what you want to do.

I probably would not replace the coupling caps unless they are leaking voltage badly.

The reason being, that some of those vintage polyester caps really sound good in old amps.

The same can be said for the old carbon comp plate resistors.

I would measure the values for drift and if not too high I would give them a listen before replacing.

Some guys don't like cap cans but a lot of those old amps have them.

Believe it or not you can change the tone of the amp by messing with the power supply because what is a amplifier?

Many times people will love that old tweed or blackface Fender but then something happens and it needs servicing.
Say the filter caps have finally let go.
They were far from what they were when first installed and have drifted, leak, and do a pretty poor job.
So you recap the amp and give it back to the customer and he says, man this thing is tight, no sag, no give and the bass sounds weird.

So on old amps I try not to over filter the supply.

It amplifies voltage from small to big and where does it get the high voltage to do that?

So for me I take a minimalist approach by doing no harm first then only replacing what really needs replacing.

[MikeHutchison]

Believe it or not you can change the tone of the amp by messing with the power supply because what is a amplifier?

Many times people will love that old tweed or blackface Fender but then something happens and it needs servicing.
Say the filter caps have finally let go.
They were far from what they were when first installed and have drifted, leak, and do a pretty poor job.
So you recap the amp and give it back to the customer and he says, man this thing is tight, no sag, no give and the bass sounds weird.

Well, to look on the bright side, it's unplayable now so I won't have the 'before' to yearn for afterwards no matter what I do!

I know the old can caps had pretty abysmal tolerances; in the +50/-25 range, and presumably the amps were designed with this in mind... with that said, have you ever experimented with purposely puting in ps caps of a lower uF than stock to get the same effect as worn out ones?

[Structo]

No not really.

New electrolytics are much more efficient than the old ones for leakage and ESR.

If you go too low it won't eliminate the 60 Hz and 120Hz hum.

[MikeHutchison]

Sorry for the delay, here are some more pics as promised:

[img1200]http://2.bp.blogspot.com/-xtxt4D4kqbo/U ... side+1.jpg[/img]

[img1200]http://3.bp.blogspot.com/-ta_cao2Xx_c/U ... side+2.jpg[/img]

[img:902:697]http://4.bp.blogspot.com/-YLi5k4HwNSs/U ... ematic.JPG[/img]

I'm taking my time with the restoration. I went ahead and ordered one of everything from the schematic, but will only be replacing what's absolutely necessary to begin with... so PS caps. Will of course put up pics as that progresses.

[Structo]

Holy Cow!

That think looks almost brand new!

Love to see some more photos of the amp and cabinet.

[parl]

Old thread I know,.. I'm guessing this is not the schematic for the R15T...
I own the R15T [second owner, uncle bought it new]
the amp still sounds sweet. [even after my punk rock years]