I love love love my Mk2. I am much more interested in sweet bass nectar than minimal THD. JMHO.
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The Un-Official Sadowsky SA200 Thread...
- Thread starter jokerjkny
- Start date
The max. heat/ time and power ratings as well as the capacitance from those electrolytic power supply caps would be interesting, that would say something about the quality. The six and four bigger caps which are blue in the MK1 and black in the MK2.
It looks like the yellow caps are the same, in but that board looks definitely different.
and some components are also different. That does not necessarily mean its not good.
Without comparing the schematic diagrams, and with that, knowing the PT and PS specs, its impossible to say whats different and if it is really optimised for KT88.
Also be aware not every KT88 is really a KT88, some of them are 6550 in a Kt88 bottle.
As I mentioned before, EL34B STR which have a G2 screen rating of 500V, work with out a problem in the in the MK1, where regular EL34 are not. mainly due to the fact that the G2 Voltage is to high for regular EL34.
Since 2012, I have changed tubes 2 times in my amp.
First time because I got it with shot tubes EH6550. Very bad idea.
Since I didnt know about the G2 voltage problem, I got regular EL34s.
And of course, they failed very soon, something like 2 months.
After that disaster I learned about the G2 Voltage Issue, and got EL34B STR.
Those lasted about 4 years. Then, one Tube started humming
During the service today, I recalled that some where drifting too.
Right now as we speak, I just finished the service on my amp.
That after 5 years of flawless operation on a regular basis at max. Volume with my Drum Students. I use a Cali1176 to tame transients and it allows to run it very close to max output. So far this set of tubes lasted about 2000 - 3000 hours of heavy use close the limit.
The reason i checked what's going on in there was, since about a month or two, it had a little less output then before.
That is usually either one power tube about to fail or bias drifting, or the PI tube is shot. Actually thats a other weak point, the 6N1P is also running quite on the limit
Luckily, It was not a failing or drifting tube, one power tube was biasing out of spec, 23-24mV, while all the others where at the high end 30mV. So to far apart but all stable.
I thought: "damn, I don't want to use my backup six pack yet".
Just in case, I always have a spare matched six pack and several 6N1Ps.
So I checked the old set from 10 years ago.
3 where drifting and 3 where fine, and ONE actually fitted perfectly.
Funny thing is such a close matched six pack I never had.before.
All the tubes bias within 28.2 and 29.2 mV.
I also put in new inverter tube and checked the balance with the oscilloscope.
It took a couple of hours but now its as good, if not better than before.
lets see how long that lasts I`ll post when it fails.
By the way we have 235Volts over here, I measured that today, the Amp running with all Tubes in it.
But the PT was made with 220V in mind …
What that does,
Instead of 490V there is 520V at pin4 = G2
490 is 10V below the rating of the STR.
Get the drift ?
I looked at the PS schematic today and was trying to find a good a good way to lower B+ about 25-30 Volts.I could change resistors bur, I cant really see. 100% what else will be affected, So I better ask some guy I know and see what he says.
But that would definitely bring the STR from a slightly hazardous in to the safe zone.
A other point is, people tend to forget, these are Chinese made tubes, they are good, but its not the same as a military grade =C= from 1980.
So far it looks like 34B STRs work well.
Just throw STRs in there and don't hit core saturation all the time.
FYI, don't take my comment to mean the Mk2 is optimized for KT88. AFAIK it is now the recommended tube for both the Mk1 and Mk2. This advice comes directly from Roger Sadowksy, and I think he probably knows a bit about any problems the amp has had.
As I am sure you know, the original tubes were the EL34B-STR you mention, and AFAIK they are about the best EL34 you can buy for an amp that runs challenging voltages. The comments from Sadowksy are the screens are run too aggressively for the EL34B-STR.
As far as not hitting the limits of the amp, it's a relatively modestly powered design, and most people who love all tube heads tend to prefer output tube saturation to preamp tube saturation. So I don't think it's necessarily a reasonable suggestion to say put EL34B-STR in the amp and then turn it down. IMHO if you are getting good life out of EL34B-STR then stay with it. But if you are burning through EL34B-STR too quickly, try KT88.
Eventually I plan to run KT88 in one of my SA200s just to satisfy my curiosity. FYI: The recommended bias for KT88 is 30mA--the same as with EL34B-STR. Reports from people who have already switched suggest the tone is not that different. Here is a post from someone who has actually run KT88 in the SA200: The Un-Official Sadowsky SA200 Thread...
If I don't like the results, I have a brand new set of Koch labeled EL34B-STRs in reserve. Also plenty of my amps are setup for KT88 so the tubes will eventually find a home.
The biggest problem with running KT88 AFAIK, is they are significantly more expensive than EL34B-STR. I know you have also brought up that the impedance of KT88 is different than an EL34, but if the tube sounds great and is reliable, I don't really see this as a problem. Also, AFAIK, biasing the KT88 (cold) at 30mA raises the expected impedance.
To clarify, the schematic is labeled 100V, 115V, 230V. AFAIK the 230V setting is intended for 220-240V as the line voltage standard varies somewhat across Europe. I do agree that the higher the amps operating voltage, the harder it will be on the tubes.
I looked in this thread but couldn't find anything. So I'll ask:
Is there a difference between the SA200 90s edition vs the 2000s edition?
Cabs?
Im expecting delivery of a 90s version with 2 210s and I'm curious. At this point it doesn't matter considering the scarcity but I'd still like to know. If there are any significant differences I may keep an eye out for one if the newer ones and move the 90s one.
Hoping someone can provide some insight.
Is there a difference between the SA200 90s edition vs the 2000s edition?
Cabs?
Im expecting delivery of a 90s version with 2 210s and I'm curious. At this point it doesn't matter considering the scarcity but I'd still like to know. If there are any significant differences I may keep an eye out for one if the newer ones and move the 90s one.
Hoping someone can provide some insight.
This is covered in the following posts:
The Un-Official Sadowsky SA200 Thread...
The Un-Official Sadowsky SA200 Thread...
Original
Mk2
AFAIK, the circuits are electronically identical.
Bottom line is the original run seems to be preferred.
Another important tidbit: The output tube recommended for the amp is now KT88:
The Un-Official Sadowsky SA200 Thread...
The Un-Official Sadowsky SA200 Thread...
The Un-Official Sadowsky SA200 Thread...
Hall of Fame epic thread here!
Thanks to all of you for killer amp talk and gorgeous pics.
Thanks to all of you for killer amp talk and gorgeous pics.
This thread is BAD!!!! Now I'm googling V8s and I don't mean cars… Damn You GAS!!!!
This thread is awesome—I will contribute to the collective G.A.S. with this pic from summer 2020. (Yes, I pinch myself that this really DID happen… thank you, TB!)
- Apr 3, 2003
- 35,518
- 19,954
- Disclosures
- Editor-in-Chief, Bass Gear Magazine
Double SA410's for the win! This is the way.
In all honesty, the SA200 is a totally different beast with two SA410's (or two Berg HS410's of course being very similar) than it is with a single SA410 or even the SA210/SA410 stack.
- Apr 3, 2003
- 35,518
- 19,954
- Disclosures
- Editor-in-Chief, Bass Gear Magazine
Pretty sure I did so years ago, but I don't have any notes laying around (which I sometimes do). No reason to think they wouldn't pair up quite well, though I normally used my NV series Bergs with my 728.
Hello again SA200 brethren! I took delivery of my SA200 today and I noticed that it did not come with rack ears. Can anyone recommend any rack ears that would work with this beast?
Anything I should be concerned with when mounting on a rack? As always, thank you for your insight!
Anything I should be concerned with when mounting on a rack? As always, thank you for your insight!
I can't think of any unusual concerns with racking the amp.
AFAIK the rack ears should have come with the amp. I believe they are OEM custom, so I would not expect an off-the-shelf solution.
The amp was made by Koch Amps. They responded and helped me when a 1/4" speaker output jack failed. Here is the Support Portal: Koch Support page - Koch Amps (koch-amps.com) Send them a message and see if they can help. Sometimes they respond quickly, and sometimes they don't.
You could also try contacting Sadowsky, but I would be surprised if they stock the rack ears: Contact Us - Sadowsky Guitars
Thank you! I reached out to Koch via message & I also posted on the Sadowsky group on FB which I believe is moderated by Roger.
Thank you for the insight!
Thank you for a very knowledgeable post. My showroom SA-200 has been much improved by going to KT88s.
My tech...the amazing legendary Blackie Pagano, informed me of the voltage issue with the EL34s. I personally recommend the change.
- Apr 3, 2003
- 35,518
- 19,954
- Disclosures
- Editor-in-Chief, Bass Gear Magazine
