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    Prototype 125 watt monoblock tube amplifier KIT

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    Bob Latino
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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by Bob Latino on Sun Oct 31, 2010 11:41 am

    dynacophil wrote:how much will the fish be...? I like what I see...
    Hi Phil,

     I have done a full cost analysis on the M-125 amp KIT. The amp kit will sell for $829 + shipping with no tubes included. (Note - on 9/1/14 - Price is now $869 per monoblock) Of course you will need two M-125 amps for a stereo system so > $1658 + shipping for a pair of M-125's. (Now > $1738 for two M-125 kits)

    All M-125's will come with a 16 gauge heavy duty chassis, power supply upgrade caps and Russian PIO main coupling caps. There won't be any options on the M-125 and I won't be stocking tube sets for these amps. As on the ST-120 amp kit, there will not be any 240 volt version of the M-125. (NOTE - added 11/17/13 > The M-125's are now available in a 240 volt version for +$50 per amp. There is also a 4 week wait before I can ship because the 240 volt power transformers for the M-125's are a special order item)

    Bob


    Last edited by Bob Latino on Thu Jan 01, 2015 10:55 pm; edited 5 times in total

    dynacophil

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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by dynacophil on Sun Oct 31, 2010 12:52 pm

    Hi Bob!

    that's a very reasonable price I guess... What a Face
    shipping to germany would be in the range of 150-200$ per amp?
    ooooh, plus ~22% tax/customs probably scratch will end up with 2500$ I believe.

    A stepdown transformer of 750W or more is here anyway. I got some of 120V gear.

    I'm not Phil, I'm Helge. The ...phil is the german written ...phile.


    Thx, Helge


    mmmh... have typed a signature, but isn't shown...?
    Do I have to activate it somewhere?

    Bob Latino
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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by Bob Latino on Sun Oct 31, 2010 1:14 pm

    Hi Helge,

    Sorry about the name thing ... Ok - "Dynacophil(e)" - a fan of Dynaco tube gear ..

    I only ship out of the USA and Canada by USPS Express Mail International. Express mail has a tracking number and you will have to sign for both amp kits when they arrive. This is to assure me (and USPS) that they were delivered.

    To ship each 37 - 38 pound M-125 amp kit by USPS Express Mail International to Germany is about $190 USD.

    Bob


    Last edited by Bob Latino on Mon Nov 01, 2010 12:40 pm; edited 1 time in total

    dynacophil

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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by dynacophil on Sun Oct 31, 2010 1:21 pm

    Thx again,
    right, this is what I am since a coworker gave me an PAS-3x for a moving help...

    As I thought, and feeding our customs ends with ~2500$ delivered ... plus tubes.
    If I have some good extrajobs and/or a good tax refund... maybe possible Xmas 2011
    Other variation would be 2 MKIII... enough of power for me.

    That signature-feature doesn't work, "show signature always" is activated...

    Best, Helge

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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by Bob Latino on Thu Nov 04, 2010 3:32 pm



    I now have the production driver boards. I will be picking up the chassis tomorrow - 11/5/10. The transformers, however, won't be ready until Thanksgiving week Nov 22 - 26. We should be set for a Dec 1 "launch" of the VTA M-125 amp kit.

    Bob



    Last edited by Bob Latino on Sun Nov 14, 2010 10:29 pm; edited 3 times in total

    RockyAM

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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by RockyAM on Sat Nov 13, 2010 8:47 pm

    Hey Bob, Dynaco at one time had some 120? watt monoblock amps called the Mark VI. Are your monoblock amps anything like the Mark VI? RockyAM

    Bob Latino
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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by Bob Latino on Sat Nov 13, 2010 10:16 pm

    Not really .. The Dynaco Mark VI was a 120 watt monoblock amp from the mid '70's. The only thing about the M-125 that was similar to the Mark VI was the fact that both amps used a parallel push pull output circuit. There are many differences between the two amps.

    1. The M-125 can use 6550, KT88, KT90, KT100 and KT120 output tubes whereas the Dynaco Mark VI driver circuit was designed for an 8417 output tube. Dynaco mentions in the Mark VI manual that there is no substitute for the 8417 tube.

    2. The driver circuit on the Mark VI used a single 7199 driver tube for both the voltage amplifier/inverter sections. This is similar to the drive circuit on the ST-70. The M-125 uses two 12AU7 or 5963 or 5814 or 6189 or 12BH7 tubes. The front driver tube is the initial voltage amplifier and the rear driver tube is the phase splitter/phase inverter tube.

    3. The Mark VI had only 75 uF of DC power storage to power the output transformer. (25 uF before the choke and 50 uF after the choke) The M-125 has 336 uF of DC power storage for just the output transformer which is about 4 1/2 times what the Mark VI had. The M-125 also has another 167 uF for just the driver board. This is not said as an indictment of the Mark VI. Back in the mid '70's the state of tube amplifier development was such that it was difficult to get a lot of DC power storage at a reasonable price. Today's electrolytic caps are smaller in relation to how much DC storage they have and are also less expensive than what was available back then.

    4. The Mark VI had a built in solid state rectifier and a delay circuit. The delay circuit, however, only delayed B+ high voltage to the DRIVER circuit. There was no B+ delay on the Mark VI to either the output tubes or the output transformer. When you turned the Mark VI on, the four output tubes and the output transformer looked at 500 VDC instantly. Some say this is bad for the output tubes and you will get "cathode stripping" on the output tubes but as I mentioned in another post I don't think it's a major issue. The Dynaco SCA-35 and ST35 both have solid state rectifiers with no delay and thousands of these amps are still out there working fine. On the M-125 I recommend the Weber WZ68 which has a short built in delay that Weber says is about 3 seconds but I have measured maybe 5 seconds before B+ high voltage is all the way up. There is also a tube rectifier option for the M-125. If you use a tube rectifier (GZ34) with the M-125 using four output tubes (125 watt mode), the amp will play fine but will not produce full power with a GZ34 tube rectifier in there. I have, however, used a GZ33 tube rectifier in these amps. A GZ33 tube rectifier with a choke input can flow up to 300 milliamps continuous. I haven't measured the power output with a GZ33 tube rectifier but I feel it does a better job than a GZ34 in driving this amp. For full power with four output tubes a solid state rectifier is a better choice. I have also use the T-SSR01 solid state plug in rectifier from Antique Electronic Supply and, although it has no delay, it also works fine in the M-125.

    One final note here about GZ34 rectifiers in Dynaco amps that has been talked about in a couple of posts. You should never "short cycle" any Dynaco tube amp. Short cycling is when you turn the amp OFF after it has been ON for a period of time and then turn it back ON quickly (within maybe 10 or 15 seconds). This short cycling can take out a rectifier tube - the usual sign being "fireworks" inside the rectifier tube. Why does this happen? When you turn the amp OFF the voltage on the rectifier tube drops almost instantly but the quad cap holds the voltage for a longer period of time. If you turn the amp right back on and the voltage on the quad cap (has not as yet bled away and) is substantially higher than the voltage inside the rectifier then current will flow backwards from the quad cap into the rectifier and sometimes this reverse flow will take out the rectifier in an internal display of "fireworks" inside the rectifier tube. If you shut a Dynaco amp OFF I recommend leaving it off for at least one minute before turning the amp back on again. In that one minute the voltage on the quad cap will bleed down to almost nothing and when that amp is turned on again the current will flow from the rectifier tube TO the quad cap and not in the reverse direction. You can also put diodes in line with power transformer's secondaries to prevent this backward flow of current.

    There was a pretty good discussion of this on a couple of threads from June and July of this year on the DIYAudio tube forum at the two links below.

    http://www.diyaudio.com/forums/tubes-valves/171019-st70-standby-switch-cathode-stripping-ss-rect.html

    http://www.diyaudio.com/forums/tubes-valves/168981-lets-settle-b-cold-tubes-issue.html

    Bob


    Last edited by Bob Latino on Thu Jan 01, 2015 10:57 pm; edited 1 time in total

    Gregg357

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    Multiple unit build

    Post by Gregg357 on Fri Nov 19, 2010 5:10 pm

    Bob,
    Money concerns aside, would you suggest a builder build both channels side by side, step by step, or rather build the left channel then build the right channel? Parallel vs Serial, I guess. Silly question, but I want the opinion of one who has build hundreds of amps. Thanks.
    Gregg

    Bob Latino
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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by Bob Latino on Fri Nov 19, 2010 5:40 pm

    Gregg357 wrote:Bob,
    Money concerns aside, would you suggest a builder build both channels side by side, step by step, or rather build the left channel then build the right channel? Parallel vs Serial, I guess. Silly question, but I want the opinion of one who has build hundreds of amps. Thanks.
    Gregg

    Hi Gregg,

    A good question and I have thought about this issue ..

    I think that the best bet here is to build one amp completely rather than go back and forth doing the same step on two different amps. My feeling is that there is more chance for error going back and forth between two amps. If you get tired you could get confused. Doing two amps at once you would need a larger work space and have two sets of parts ready. This, IMHO, is a good recipe for making mistakes like grabbing the wrong resistor...

    If you order TWO amps (and most builders will) I am advising going through the manual and building ONE amp and circling each step as you complete the step. The next run though with the other amp place a check beside each step number.

    Speaking about ONE amp > I have had some inquiries about the use of one M-125 amp as a "guitar amp". This could be easily done. All you would have to do is swap out the RCA input for a 1/4 inch phone jack that guitars use. I actually have two customers that use my ST-70 kit as a guitar amp. I am not sure if the run the amp in mono OR run each channel into an individual speaker.

    Bob

    Gregg357

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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by Gregg357 on Tue Nov 30, 2010 6:00 pm

    Bob,

    How are you doing? Are you still on your original schedule for the M-125 release?

    Gregg

    Bob Latino
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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by Bob Latino on Tue Nov 30, 2010 6:28 pm

    The final parts needed to complete the M-125 kits will be shipped to me this Friday, Dec 3rd. I should have everything on Tuesday, Dec 7th. Sorry for the delay but I have no control many times over when items are shipped. I will post a notice in this thread when the M-125 kits are ready ...

    Bob

    evilfij

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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by evilfij on Sun Dec 05, 2010 3:21 am

    Bob,

    I emailed you a while back about a pair of these and I figured I would ask my additional questions here for the benefit of all (as opposed to just me).

    Background is that I would be running them to Magnepan 1.6QR.

    1. Can I run stock design dynaco mkiii boards in these? I know this is counter to the whole update the driver board mentality (which I fully support), but I really enjoy the sound of the 7199 driver board in my mkiii and I would like to keep the same sound. Horses for courses and all that. I note the boards I would use have 600 vdc caps.
    1(a). Part of the reason I would like to run a mkiii driver board is to fit a preamp power socket to run my PAM-1 preamps. Would this be possible?
    2. Can I delete the triode switch wiring? This is mainly an appearance issue.
    3. Is there any issue with me changing the chassis a bit and running a dynaco style power switch rather than the toggle switch? This is mainly an appearance issue.
    4. There are only two speaker taps (rather than four on a stock mkiii), is the amp designed for a 4 ohm or 8 ohm load? I know you said you ran the Magnepan 3.6 with them (which is 4 ohm), how is it possible to run both 4 ohm and 8 ohm on the same tap? I assume it is designed for a 4 ohm load and the 8 ohm just stresses the amp less.
    5. You mentioned running a Gz33 rectifier or a GZ34 rectifier rather than a webber cap. You also mentioned a GZ34 rectifier would limit power output. Why, because you have to run at a lower bias? Also, is there a similar limitation with the GZ33? What do you expect the reliability to be like on the rectifier tubes in either case?

    Sorry if these are dumb questions. I am new to this. I do have some ideas as to the answers, but I figured I would go to the source to make sure they were correct.

    Best,

    Ron

    Bob Latino
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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by Bob Latino on Sun Dec 05, 2010 8:49 am

    evilfij wrote:Bob,

    I emailed you a while back about a pair of these and I figured I would ask my additional questions here for the benefit of all (as opposed to just me).

    Background is that I would be running them to Magnepan 1.6QR.

    1. Can I run stock design dynaco mkiii boards in these? I know this is counter to the whole update the driver board mentality (which I fully support), but I really enjoy the sound of the 7199 driver board in my mkiii and I would like to keep the same sound. Horses for courses and all that. I note the boards I would use have 600 vdc caps.
    1(a). Part of the reason I would like to run a mkiii driver board is to fit a preamp power socket to run my PAM-1 preamps. Would this be possible?
    2. Can I delete the triode switch wiring? This is mainly an appearance issue.
    3. Is there any issue with me changing the chassis a bit and running a dynaco style power switch rather than the toggle switch? This is mainly an appearance issue.
    4. There are only two speaker taps (rather than four on a stock mkiii), is the amp designed for a 4 ohm or 8 ohm load? I know you said you ran the Magnepan 3.6 with them (which is 4 ohm), how is it possible to run both 4 ohm and 8 ohm on the same tap? I assume it is designed for a 4 ohm load and the 8 ohm just stresses the amp less.
    5. You mentioned running a Gz33 rectifier or a GZ34 rectifier rather than a webber cap. You also mentioned a GZ34 rectifier would limit power output. Why, because you have to run at a lower bias? Also, is there a similar limitation with the GZ33? What do you expect the reliability to be like on the rectifier tubes in either case?

    Sorry if these are dumb questions. I am new to this. I do have some ideas as to the answers, but I figured I would go to the source to make sure they were correct.

    Best,

    Ron

    Hi Ron,

    1. No - The stock Dynaco Mark III driver board with 7199 doesn't have enough voltage swing to run in this amp AND ATTAIN FULL POWER.

    1a. Unless you want to cut a 1 1/8 inch hole on the front yourself for the preamp power socket, there is no place to plug in the power take-off. Solution (and I don't mean to be harsh here) BUT > Sell your two PAM-1's. There are much better preamp's out there that you can use with the M-125's. The PAM-1 was designed in 1955 and preamp designs have come a long ways in 55 years.

    2. Yes - the triode pentode wiring can be deleted and the amps may be run in just pentode ultralinear.

    3. Unless you want to cut into the chassis to install a slide switch. Slide switches made today have an 11 amp maximum rating. The toggle switches I use are heavier duty and are rated at 15 amps. The toggle switch that I use for the power switch also matches the toggle switch for the triode/pentode ultralinear switch.

    4. The amp may be set up for 4, 8 or 16 ohms. It is a very simple matter also to switch from one impedance to the other. You just move one wire inside the amp. When I ran these on the Magnepan 3.6's I just switched to the 4 ohm tap.

    5. The Weber WZ68 will flow 450 milliamps, a GZ33 will flow 300 milliamps and a GZ34 will flow up to 250 milliamps. The four output tubes will eat up 220 - 240 milliamps and the two 12BH7's maybe 10 - 15 milliamps each. On a GZ34 you are right at the limit of the tubes ability to flow current. On a GZ33 you have a small margin below the current flow capability of the GZ33. On a WZ68 you are well below what the Weber WZ68 can flow if needed.

    Bob

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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by Bob Latino on Tue Dec 07, 2010 3:58 pm

    I now have the M-125 amp kits in stock and will be advertising them for sale on Ebay and Audiogon this coming Friday - 12/10/10. I only have 16 pairs available in the initial run of these amps and 4 pairs are already pre-sold. If anyone is interested in purchasing a pair ($1698 + shipping) please send me a PM through the Forum here or Email me at Bob01605@aol.com and let me know your zip code.

    Pair of assembled M-125 amp kits shown below with an octet of Tung-Sol KT120 tubes. Note - no tube set is included with these kits. You will need 4 X KT88, 6550, KT90, KT100 or KT120 output tubes, 2 X 12BH7 or 12AU7 driver tubes and 1 X Weber WZ68 SS rectifier or GZ33 tube rectifier.

    Bob




    Last edited by Bob Latino on Sun Nov 17, 2013 11:05 am; edited 1 time in total

    cduarte

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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by cduarte on Mon Dec 13, 2010 7:30 pm

    will these work with 6l6gc or equivalent tubes?

    Bob Latino
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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by Bob Latino on Mon Dec 13, 2010 8:07 pm

    cduarte wrote:will these work with 6l6gc or equivalent tubes?

    You CAN use 6L6 output tubes in these amps but IMHO KT88, 6550 or KT120 tubes are a better choice. The amp operates at 500 - 515 VDC which would be hard on any 6L6 tube. My feelings are that 6L6 type tubes would have a short life in the M-125 and I personally do not recommend their use in this amp. The same goes for EL34, KT66 or KT77 tubes - not recommended for use in this amp.

    Bob

    Gregg357

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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by Gregg357 on Thu Dec 30, 2010 7:06 pm

    Bob,
    Couple of questions.
    1) I'm thinking of powder coating the M-125 chassis. Is this at all a problem? I'm not sure of the potential problems i'd be creating, if any. If I do, should I leave the insides uncoated? Any ground issues? Would the chassis cut outs get filled in? I'm just looking for a non-silver coloring that will stay unchanged for a couple decades.
    2) Should I be concerned with static in my work area? My office has heat via forced hot air and can get "staticy" at times. Do I need a mat or a "wrist tie off"?
    3) You mentioned in one exchange that maybe a 60w iron should be used for connections to the chassis. Is this a problem if the entire job is done with a 30w pencil?
    4) Am I over complicating things?

    Gregg

    Bob Latino
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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by Bob Latino on Thu Dec 30, 2010 8:26 pm

    Gregg357 wrote:Bob,
    Couple of questions.
    1) I'm thinking of powder coating the M-125 chassis. Is this at all a problem? I'm not sure of the potential problems i'd be creating, if any. If I do, should I leave the insides uncoated? Any ground issues? Would the chassis cut outs get filled in? I'm just looking for a non-silver coloring that will stay unchanged for a couple decades.
    2) Should I be concerned with static in my work area? My office has heat via forced hot air and can get "staticy" at times. Do I need a mat or a "wrist tie off"?
    3) You mentioned in one exchange that maybe a 60w iron should be used for connections to the chassis. Is this a problem if the entire job is done with a 30w pencil?
    4) Am I over complicating things?

    Gregg

    Hi Gregg,

    1. I don't see any problem powder coating the outside of the chassis. I wouldn't powder coat the inside of the chassis because you have to ground to the inside of the chassis.

    2. I have never used any "wrist tie off" in building the driver board or amp itself. I don't feel that doing so is necessary.

    3. You CAN do the whole job with a 30 watt soldering pencil. In a few areas like soldering onto the output binding posts you could use a little extra heat. The output binding posts have more mass and it will take longer to heat up than if you had a soldering pencil with more wattage - but it can be done with a 30 watt pencil.

    4. No - The questions that you ask are valid considerations.

    Bob

    Gregg357

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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by Gregg357 on Thu Dec 30, 2010 9:57 pm

    Bob,
    Thanks for the quick reply. I've got my EH tubes from Jim McShane and my Weber WZ68's. Just about to start the project. I'm not going fast, I just hope to have them up and running on the first shot.
    Gregg

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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by Bob Latino on Thu Dec 30, 2010 10:54 pm

    Hi Gregg,

    I have had a couple of reports from earlier builders and they have had no issues and the amps have worked fine. Let us know how you make out with the assembly ?

    Bob

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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by Bob Latino on Tue Jan 04, 2011 9:18 pm

    Just a note to all ... Half of the initial run (8 of the 16 pairs) of the M-125's have been sold in the first month of sales (since Dec 7th). I have 8 pairs left as of Jan 4, 2011. Initial reports from the first few kit builders regarding ease of assembly and sound quality have been very good. I do have to take some responsibilty for a minor error by myself to the first three kit builders. I sent them the wrong number of 4-40 screws. Somehow I sent them just 14 4-40 stainless steel screws and nuts for each amp when in reality each M-125 required 18 4-40 stainless steel screws and corresponding nuts.

    Bob


    Last edited by Bob Latino on Sun Nov 17, 2013 11:06 am; edited 1 time in total

    RockyAM

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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by RockyAM on Sun Jan 09, 2011 2:36 pm

    Hey Bob, I noticed that you are using two chokes on the M-125 monoblocks like on your ST-120 amplifier but you don't do that on the ST-70 kit. Any reason why you use the two chokes on these monoblocks? can't you maybe use like one bigger choke? Rocky M.

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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by Bob Latino on Sun Jan 09, 2011 3:33 pm

    Hi,

    The reason for using two chokes instead of one is that two chokes can handle (together) more current than a single choke. The original Dynaco C-354 choke on the ST-70 had a rated continuous current handling capacity of 200 milliamps. When you bias an ST-70 at 1.56 VDC per channel, each tube is biased at 50 milliamps. This eats up the entire 200 milliamp rating of the choke without even figuring the current used by the two 7199 tubes and the rectifier tube. Since an original ST-70 choke rarely goes bad, I suspect that the current rating on these chokes was conservative. In an original ST-70 though these chokes do get pretty hot after hours of continuous use of the amp. Many an original ST-70's C-354 choke will melt out a "brown goo" after years of heat abuse. Since the choke is in the upside down position in the amp, the "brown goo" usually drips down onto the amp's bottom cover under the choke. If you have an original choke and it is leaking you should replace it with a new C-354 choke from Dynakitparts. The C-354 chokes from Dynakitparts are better made than the original Dynaco C-354 chokes and won't leak. To test a choke in an ST-70, by the way, just measure across the two quad cap terminals that the choke is connected to with the amp OFF. If you get somewhere between 45 and 65 ohms, the choke is probably OK. If it is leaking, though, I would replace it with a new C-354 choke from Dynakitparts.

    The ST-120 and the M-125 amps each use TWO C24-X chokes which are the same physical size as the C-354 in the ST-70. The C24-X chokes, however, are rated at 240 milliamps each. When two are used together, they give a current handling rating of 480 milliamps. In the M-125 the four output tubes are biased at 60 milliamps each and in conjunction with the two driver tubes and rectifier give a current flow well over 240 milliamps. I could have used a single larger choke but it wouldn't fit inside the 1 3/4 inch depth of the M-125 chassis so you would, if you used a single larger choke, have to find a spot on the TOP side of the chassis to mount the choke. The topside choke also has the issue of two very visible wires protruding through a hole in the chassis AND each wire is carrying 500 - 515 VDC. Keeping the choke inside the amp is (IMHO) a safer bet.

    Bob

    GP49

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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by GP49 on Mon Jan 10, 2011 12:30 pm

    Drifting a bit off topic, I've always suspected that the reason the Dynaco ST-70 filter choke runs at its limits, and therefore hot, is because the original use for the choke was for the Mark III, to give it a higher B+ voltage than the Mark II from which it was designed without a new power transformer. In the Mark III application it only had to supply two KT88/6550 and one 6AN8, not four EL-34 and two 7199.

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    Re: Prototype 125 watt monoblock tube amplifier KIT

    Post by Bob Latino on Mon Jan 17, 2011 10:10 am

    GP49 wrote:Drifting a bit off topic, I've always suspected that the reason the Dynaco ST-70 filter choke runs at its limits, and therefore hot, is because the original use for the choke was for the Mark III, to give it a higher B+ voltage than the Mark II from which it was designed without a new power transformer. In the Mark III application it only had to supply two KT88/6550 and one 6AN8, not four EL-34 and two 7199.

    GP,

    I have to agree with you ... That same choke was used in the Mark III, Mark IV and ST-70. In the ST-70 it runs noticeably hotter - no question BUT - rarely does an original C-354 go bad so maybe the 200 milliamp rating was conservative ?

    Bob

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