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Bogen MO-100A vs Dynaco Mk VI?

analog addict

analog addict

Glory or Death!
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Trying to decide which direction to go as I look at thinning the herd. I have a pair of the Dynacos, which I've been told are fairly rare at about a thousand pairs made. I also have a nice single Bogen MO-100 A, which also uses the 8417 in PPP. Both amps are in the 100-120 WPC range, but which would most consider to be the better amp?

I'm trying to decide if I should chase another one of the Bogens.....:scratch2:

http://www.bogen.com/support/discontinued/pdfs/MO100Am.pdf


http://www.dvq.com/hifi/images/dyna_mk6.pdf
 
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For high fidelity service, the Dynaco has it all over the Bogen in numerous ways, not the least of which is the fact that the Dynaco has a superior output transformer, a true 8 ohm output tap, lower distortion, and a more reasonable sensitivity level. This is not to trash the Bogen at all. It's a good amplifier. But the Dynaco is ultimately capable of superior performance.

Dave
 
dcgillespie said:
For high fidelity service, the Dynaco has it all over the Bogen in numerous ways, not the least of which is the fact that the Dynaco has a superior output transformer, a true 8 ohm output tap, lower distortion, and a more reasonable sensitivity level. This is not to trash the Bogen at all. It's a good amplifier. But the Dynaco is ultimately capable of superior performance.

Dave
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Fair enough Dave....Thanks!:thmbsp:
 
dcgillespie said:
For high fidelity service, the Dynaco has it all over the Bogen in numerous ways, not the least of which is the fact that the Dynaco has a superior output transformer, a true 8 ohm output tap, lower distortion, and a more reasonable sensitivity level. This is not to trash the Bogen at all. It's a good amplifier. But the Dynaco is ultimately capable of superior performance.

Dave
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Interesting, Dave. Are these comments based on your experience or/and measured data in addition to comparing the data sheets & specs of the stock units? I'd be interested in seeing any actual measured data if you have it; I haven't seen much out there.
 
Tink -- As would I like to see some measured data as well! I wish I could say I had some hard information, but I do not. However, my comments were based on these thoughts:

1. The Bogen was designed from the ground up as a sound distribution amplifier, with it's 25 & 70 volt output taps, where as the Dynaco was aimed at being a sound reinforcement amplifier, having only traditional 4-8, and 16 ohm output taps.

2. The extra windings in any OPT that supports distribution voltage levels always plays havoc with the HF response of any OPT so designed. The Dynaco OPT does not have to contend with this baggage.

3. The Bogen is a pentode design, where as the Dynaco is a UL design, which will give the Dynaco a significant edge in damping control.

4. The calculated FB level, along with the manufacturer's specifications shows the Dynaco to have lower distortion and greater sensitivity at more power output than the Bogen design does (at least as compared to one of its amplifiers) -- again giving weight to the Dynaco's edge in starting life as a high fidelity product.

Once again, I am hardly trashing the Bogen amplifiers. In fact, the specifications for them shows superb performance on the low end, which is more in keeping with high fidelity standards than distribution amplifier standards. And like you, I hope that if anyone has any hard data that they would provide it -- if only to either give some credibility to my thoughts, or prove them to be all wet!

Dave
 
Thanks, Dave; I appreciate the input and the comments seem founded on sound reasoning.

I have not heard the Dynaco Mk VI but have several different Bogen "M" series amps and have been pleasantly surprised with their performance at both low and high end (from listening experience not by measuring data). Maybe one of these days I'll get around to doing some measurements - or maybe we can talk Allan (analog addict) into doing some comparative measurements being as he has both Bogen and Dynaco. :smoke:
 
I think those 8417 based Bogens were used for more than PA system amplification. I think they were also designed to be used for various industrial applications like shaker tables. I have an MO-200A I got at a silent auction from my employer at the time. I worked for a major heavy-duty engine manufacturer, and they'd periodically hold silent auctions to allow their employees to buy surplus equipment. (I also got my Hicock tube tester at the same time.) I believe that the amp I bought had been used to run a shaker table or some other kind of fatigue tester in one of their met labs.
 
The bogen mo-100 with kt88 tubes is very similar to the quicksilver kt88 monos with better output iron and can sound very good in refurbished condition. Of course prices have gone up a lot on the bogen stuff in the past five years but I had a rebuilt mo-100 mono block setup and thought that they were very good sounding.
 
I have one Bogen MO-100A.
Spec.'s from a 1969 Radio-Electronic Master:
Output= 100w @ 2% dist.
Freq. Resp.= 8-50khz +/- 1db
Hum= -80db

I'd like to find another for the few $'s I got this one for!
 
I'd pick the Bogen

In my tube rack I have a Marantz 8B, a Harman Kardon Citation II rebuilt by Jim McShane, a Fisher SA-1000 and a pair of Bogen MO-100A monoblocks . I keep the Bogens hooked up all the tme. I prefer them to all the above..and they have all been upgraded by different people. (The Marantz by VTV, the Fisher by Terry DeWick, etc.)

If you haven't heard the MO-100 you really can't speak to it. It is right thee with all the GREAT tube amps of the day, and it holds its own. The iron in it is top notch. I did own a pair of Quicksilver monoblocks which I understand were designed after the Bogens, and I have since sold the Quicksilvers.

For what it is worth.....

I'd love to hear the MO-200. Does it have larger trannies? Use 8 8417's?

Does everyone here prefer the Westinghouse produced 8417 over the RCA ones? Am I right that only these two companies evr PRODUCED an 8417?
 
I'm going to buy another pair

I'm buying another pair before they are discovered....I just bought numer 3 and am waiting for number 4 to show up. Paid 160 for the last one sans tubes...
 
dcgillespie said:
For high fidelity service, the Dynaco has it all over the Bogen in numerous ways, not the least of which is the fact that the Dynaco has a superior output transformer, a true 8 ohm output tap, lower distortion, and a more reasonable sensitivity level. This is not to trash the Bogen at all. It's a good amplifier. But the Dynaco is ultimately capable of superior performance.

Dave
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Hmmm, I shall disagree. BTW there's been a 100 on epray for a couple weeks now for 100 bucks and one with tubes for 200 (but it's gone).:para: Nobody like Dyna iron more than I, but IMHO the Dyna iron isn't even in the same league as the bogen, esp, in areas like saturation and such.
 
ksrigg said:
I

I'd love to hear the MO-200. Does it have larger trannies? Use 8 8417's?
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Same size output transformer, but two of them. Its two MO100a amps on one chassis with the outputs strapped together. It also uses a single power supply with an absolutely massive power transformer. A little bit of presto-chango rewiring and you have a stereo amp though. Yes, 8x 8417 tubes. A pair of those and you have some seriously badass monoblocks.


dammit I really need to buy some KT88's and get mine running. Winter project, sure, thats the ticket.
 
I also got a bunch of Bogens from an old company I worked for, and as great as they are I'd assume the Dynaco to be better since it was designed for HiFi use.

We also had a couple vibration tables for testing aircraft parts.
One was powered by a 10K watt TUBE amp, the other a SS Ling amp.
And yes, I did play my guitar through it once, using the vibration table as a speaker.
The most insane loud "amp" I've ever played!
 
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In the for what it's worth department, I've got a Bogen MO-200 due to show up on my doorstep any day now to go through and separate into stereo channels, and then optimize from there.

One of the things missing about these amps is any hard data, which I plan to address. There's lots of oohs and aahs as to sound quality, size of transformers and the like, and they do look impressive, but it is always best to have hard and subjective data about a given unit. Both are equally important, as either by itself only presents half the picture. When you have both, you know what you have, and can enjoy a piece on its total merits -- both subjectively and from an absolute performance capability.

As I get into it, I'll start a thread to stir things up. All comments will be welcomed!

Dave
 
Very interested in your data findings. Is this one to remain 8417, or are you doing a KT88 conversion? I have a pair of 100a's that eventually will see a quad of KT88's.
 
dcgillespie said:
In the for what it's worth department, I've got a Bogen MO-200 due to show up on my doorstep any day now to go through and separate into stereo channels, and then optimize from there.

One of the things missing about these amps is any hard data, which I plan to address. There's lots of oohs and aahs as to sound quality, size of transformers and the like, and they do look impressive, but it is always best to have hard and subjective data about a given unit. Both are equally important, as either by itself only presents half the picture. When you have both, you know what you have, and can enjoy a piece on its total merits -- both subjectively and from an absolute performance capability.

As I get into it, I'll start a thread to stir things up. All comments will be welcomed!

Dave
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Good stuff, Dave. I am looking forward to reading your progress. :thmbsp:

Hopefully we can see stock performance with original tubes vs. modified unit.
 
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