Impressions of the Dynaco MK III Tube Monoblock amps

Joe08867

H9, Maybe the JJ's were EL34 not EL34S memory isn't exactly clear on that.

The Siemens Tubes were also NOS and I am pretty sure a Tesla Product also. So I am guessing that is why they sounded so much better. And why your JJ's sound so good. They did not look the same as the current Siemens Tubes although the price is similar.

The Tung-Sol's were also NOS but the Mullard's were current production as were the Black Sable's out of St. Petersburg Russia.

heiney9

Just curious, that's all. For me being an tube head who almost always prefer's older 50-60's tubes, I am impressed with these JJ EL34S. I use the EL34 integrated in a secondary rig and as much as I want "real" Mullards, I won't pay those kind of prices for a smaller inexpensive amp used in a secondary rig.

Another thing, I meant to say the the EL34S is similar in construction to the KT77.

For those interested here is a good analysis of some of the EL34's out there. Note the EL34L/STR Harma is the same as the EL34S both made by JJ and also found rarely with a Siemens logo.

http://www.watfordvalves.com/cgi-bin/documents/testreport_46.pdf

This is an older test before some of the EL34's we have today were being made. Note the Svetlana in this test is the same as the current SED Winged "C" because this test was done before New Sensor bought the rights to the name Svetlana. They were still being made in St. Petersburg. Also note the EL34L/STR Harma still gets great reviews.

http://www.watfordvalves.com/cgi-bin/documents/testreport_32.pdf

reeltrouble1

kcoc...If the power tube will not reach its bias point then replace it. I am not sure about your hum, several possibilities from impendance mismatch through tube problem or even a ground loop issue. I also believe these amps were just worked on and you just acquired them...have contacted the seller to see if he may have any input?

I honestly do not know what the fuss is about with the JJ, I have used them and they are fine just as H9 reports, I mean here is this member with a legit question about his amps and we have posts about an EL34 tube. OK, fine, I was using Svetlana W-C, before anybody here, yes the winged C are nice.... can help kcoc?

RT1

reeltrouble1

oh and kcoc, try swapping the tube set from the amp that bias's correctly one at a time to see if you can identify a tube problem...the thing with tester's is their is no standard, eash manufacturer establised their own baseline as to what is good or bad as far as a tube tester.

RT1

kcoc321

Thanks RT..I will try that...I did that in conjunction with trying to eliminate the hum...but not to isolate the tube that is not biasing...another friend of mine said he thought the humm sounded like it might be a bad capacitor. Would that cause it to not Bias as well?
Sorry..so many questions....

heiney9

It could be a bad solder joint somewhere as well. Have you spoken with the seller?

H9

Joe08867

reeltrouble1 wrote: »

I honestly do not know what the fuss is about with the JJ, I have used them and they are fine just as H9 reports, I mean here is this member with a legit question about his amps and we have posts about an EL34 tube. OK, fine, I was using Svetlana W-C, before anybody here, yes the winged C are nice.... can help kcoc?

RT1

It's called a discussion. Nobody is saying that JJ's suck or anything we are discussing what we have heard with them. Hopefully giving the OP some information in the process.

Your suggestion to swap tubes one by one into the amp that biases correctly is what I would do. I am guessing it is a solder connection from traveling though. Probably one of the connections for the power tubes.

reeltrouble1

well.....Okay, statements that a tube won't give you this or that lack authentic foundation for anybody else's experience, each system provides a different musical experience dependant upon everything in that system, as such you need to provide the associated gear your finding is based upon, otherwise you end up simply confusing things.

Of course the possiblity exists a given system's gear lacks the ability for a variety of reasons to resolve a JJ EL34 to its full potential. I used them in my Wolcott based rig and heard deep powerful bass through the Sound Lab speaker.

Of course none of the above is actually helping kcoc whose thread this is afterall.

RT1

kcoc321

Thanks guys for the suggestions
I am going to try the tube swapping when I get time this evening..I am alittle 'daunted' by checking all the solder joints, but maybe that is what I have to do.
I have sent off another email to the seller and hopefully his father, who rebuilt the amp, will have some advise/ suggestions.
He did offer my money back, so that is some consolation.

I actually enjoy hearing about what aspect different tubes offer, in another time, when I can actually enjoy contemplating them. Right now I just want t o make the thing WORK...LOL

reeltrouble1

well that is a good sign of faith from the seller, you just need to decide what you want to do. The thing about tubes is they are fairly delicate machines, sound great but it just seems in this hobby the more resolving the gear the more it is prone to issues. Hope to hear you found the issue.

RT1

kcoc321

yeah, I talked to the "builder' today. I am going to bring it back to him this weekend and he is going to fix it.
<crosses fingers>

kcoc321

He is a nice older gentleman who is a retired Boeing EE. We talked about the issues I was having and gave me some things I can check out. He also has another pair that he put in AuriCaps in the inputs caps. I am inerested in hearing the difference, although he has different speakers, inless I haul some down there... I am considering doing mine too, but IDK if I would use the Auricaps or step to something better, from Sonicaps to Mundorf silver/ oil.I don't think I would go above those, there are only (2) 0.10uF and (1) 0.22uF in the upgrades Posiden input boards, so it would not be "that" much....
He also offered to replace the two chinese 21AX7's that tested low (90) even though they are new, with some other, better ones he has. And he has some GL KT-88's I might try and talk him out of. He has 8, and I only need 4, but he got them and did not like them. He did not like the bass extension. Depends on what he wants for them, I might bring some home.
So it was a good call.

reeltrouble1

so you have turned into a CP vampire....well you and F1 can prowl the board through the night:loneranger:, something we really have not talked about is impedance mismatch, when using SS with tube it is common to experience a slight hiss type sound at the speaker, not much you can do about that as its just how the gear works together. You can use ss and tube gear and have a great sounding rig so dont fret to much and I cannot be sure that is your issue. Glad you are getting together with the seller. I would hesitate to put too much more coin into these, but I can say I have certainly done such things in the past......

RT1

heiney9

That is good news the seller is standing behind the sale.

I really enjoy Auricaps as coupling caps. I know some of the other high priced boutique caps sound better but there is quite a cost difference. The main thing to pay attention to is size, as in this case it does matter.

You might consider throwing Obligotto into your choices, but for a great cost/benefit/size factor the Auricaps are really nice and don't color the sound too much.

Again good luck

H9

kcoc321

IDK if I am a vampire on his league...quite yet.....LOL

My "noise" is more like a hum than a hiss, and it is present even when a 'dummy' input is connected...
I'll get a chance to hear the AuriCaps this weekend..We'll see what differnce I can hear...does not seem to bad $$ wise over the "orange drops" that are on there now...

I will check the Obligotto out,

thanks guys

heiney9

My brother had some mono tube amps sent to him. Packed to survive a nuclear explosion and he developed a hum. After a few hours troubleshooting with the manufacturer over the phone he discovered a cold solder joint around in the output section. It happens, but it's nice the original builder is still available to help you trouble shoot.

H9

kcoc321

Thanks, IF we can't isolate it from other issues, I will definitely have him look into those pesky "Cold-solder" joints