Dirty Little Monster

[UR12]

This is an interesting thread. It will be interesting to see how close you can get to a real one without having anything real to go on but verbal descriptions. Anyway, In regards to the OT, Using a PP PT can be an option but since you have current flowing at all times on a SE amp the tranny really needs to to have an airgapped core and I would tend to believe that the higher the power the more important that becomes. Just my two worthless cents. The one SE 35watt I have spec'd out is actually 2100 ohms and is set up for two EL34s in parallel not one.

Heyboer makes a killer SE airgapped tranny. Just give them the Pri Impedance and how many watts you want it to handle and they can make it.

[dartanion]

I'm using the 35W iron that Dana spec'd. Sounds pretty great so far.

It is a beastly OT!!

[mcrracer]

So Dana, is it your expert opinion that we should forget the PP OT and stick with SE OT iron?

[RJ Guitars]

I've established a pretty good relationship with EDCOR in the last few months. They really have excellent build quality and don't mind making "one at a time" for you.

Their much better known for their HiFi transformers, so their single ended stuff will no doubt be stellar quality. It's possible it's "too good" for a guitar amp but they do indeed have a nice 25 watt SE tranny... it's not cheap either.

http://www.edcorusa.com/products/transf ... -4-5k.html

rj

[UR12]

So Dana, is it your expert opinion that we should forget the PP OT and stick with SE OT iron?

Unless Ken used some off the wall PP tranny he had lying about to get some mystical mojo thing going, (you'll probably never know for sure unless someone comes up with a real DLM to spec out) I would go for the air gapped tranny. The one I speced out for the dual EL34 I don't think would work too well. I would have one built or find one that has the right specs on a shelf like a Fender or Ampeg or something. That's just what I would do and I don't like trying to speculate what someone else might have done or could have done in regards to building a clone. Especially if you want it to come out sounding anything like the original. If your just looking to build a amp that is not a clone of a DLM then Richies Beast is hard to beat. Knowing Darin's quest for sound I would guess his would also fit the bill.

[dartanion]

Knowing Darin's quest for sound I would guess his would also fit the bill.

The Absinthe is slathered in special sauce and injected full of mojo

I took an interesting angle on SE that was suggested by a few well know ampoholics. I wanted to retain the Wreck mojo, so I retained the PI and feed the SE output section from one side of the PI. It's pretty cool and sounds great. It really isn't much different than the SE/PP control in theory.

[davent]

Doberman sell a nice Heyboer made 20w SE OT for guitar amps.

http://shop.dobermanamps.com/product-p/ ... b20wse.htm

dave

[ER]

I just built a single ended amp for my nephew based on the dearmond R5 using 6005 and the edcor open frame 5K:16 15 watt OPT. $22 for the OPT and it sounds really really good. It's also really loud for 5-6 watts, in fact it may be too loud and I'll just have to keep it for myself. The 6x4 rectifier really compresses nice for slide.

I had the 16 ohm secondary for a hi-fi project but used it for this so I hooked it up series to 2X8" alnico speakers from some old wedge cabinets I bought at the thrift store for $2, and it just screams. I can't imagine it with SS or GZ34, probably blow the thing up, as it begs to be played at "11".

Anyways I have no problem at all recommending the edcor 15W iron.

-ER

[mcrracer]

I just built a single ended amp for my nephew based on the dearmond R5 using 6005 and the edcor open frame 5K:16 15 watt OPT. $22 for the OPT and it sounds really really good. It's also really loud for 5-6 watts, in fact it may be too loud and I'll just have to keep it for myself. The 6x4 rectifier really compresses nice for slide.

I had the 16 ohm secondary for a hi-fi project but used it for this so I hooked it up series to 2X8" alnico speakers from some old wedge cabinets I bought at the thrift store for $2, and it just screams. I can't imagine it with SS or GZ34, probably blow the thing up, as it begs to be played at "11".

Anyways I have no problem at all recommending the edcor 15W iron.

-ER

Do you have a schematic which you could post. I have looked and can't find anything on the Dearmond R5. Thanks

[swarty]

The 6x4 rectifier really compresses nice for slide.
-ER

Does a rectifier sag in a SE amp?

[RJ Guitars]

I took an interesting angle on SE that was suggested by a few well know ampoholics. I wanted to retain the Wreck mojo, so I retained the PI and feed the SE output section from one side of the PI. It's pretty cool and sounds great. It really isn't much different than the SE/PP control in theory.

There is a discussion on this in Gerald Weber's book where he mentions that someone had a Princeton that sounded very cool when one of the output tubes fell out of it. The coolness went away at higher volumes when the amp went out of class A into class A/B.

If you were to bias your PP amp into full class A (I'm not saying "do this" or that "it's a good idea"), would the output sound be radically different than a set of parallel singles if you kept the major parts of the circuit up to the output tubes the same?

rj

[ER]

For R5 I used the RT5 schematic and eliminated the tremelo cuircuit.

Basically a champ/princeton with a few cap changes and odd pots.

There is a good thread on the dearmond/martin amps at the guild page: http://www.letstalkguild.com/phpBB2/vie ... f=9&t=4441
The schematic for RT5 is a few pages in.

It's funny to think the savage Mahct 6/12 goes for close to what a trainwreck went for in their day.

As far as compression I tried to get some squash and looseness everywhere I could, put a choke in place of the 500 ohm power supply off the 6x4, speakers in series etc. 7-pin output tube, etc. it was supposed to be a bedroom amp. I may need to look for a relatively inefficient 16 ohm speaker that sounds good to get the volume down some. any good sounding inefficient guitar speakers out there @ 16 ohms?

-ER

[dartanion]

There has been much debate about what class SE guitar amps actually operate. Classically, if you look at tube datasheets, class A SE is achieved at much lower plate voltages and screen voltages than what you see in most SE guitar amps. Most SE guitar amps are using close to the same Rk as specified in the datasheets for class A SE, but with much higher plate voltages, I would wager that these amps are pushing into class A/B SE operation. This means that the tube is driven into cut-off for a small portion of the cycle and asymmetric clipping is the result. This type of clipping is pleasing for use with guitars, but not HiFi. But, too much of this would sound awful, hence the case of the Princeton with one tube removed or one dead tube.

Using a PI and driving the SE output off one side works perfectly fine. The SE/PP control that you see in Mark Durham's Vajra applies a similar principal with a PP OT. This control grounds out the signal from the PI to one of the power tubes as you turn it towards SE. Both output tubes stay in the circuit, so there is no worry about changing impedance or having an air gap in the OT, etc. The only difference here is that I used a full SE PA and drive it with one half of the PI. This way you preserve the PI gain and the interactivity of the all the amp stages of a Wreck.[/list]

[mcrracer]

Any more info available?

[mcrracer]

I have built a possible contender. An Express front end on a KT88 power amp. The silicone is drying on holding the caps together in the chassis. I will put power to it Sat.
Next I will try a Plexi front end. I know, this wasn't what was reported in the original DLM but until someone actually documents one all we can do is guess anyway, I am not trying to necessarily copy Ken's work. Just want to make a good sounding SE amp...sort of a lower cost lower volume alternative to the TW. I don't have $1500 to $2000 to put into an amp. Hell I don't even play guitar, I'm a bass player! I just like to see that grin come up on the guitar players faces when they plug into a nice, new amp.