Dale W Posted May 19, 2003 Share Posted May 19, 2003 TOM : once you get those dynaco's dialed in they will kick butt Sorry i can't chime in on the mod's , i'd really like to help out. But craig did my amps start to finish so i'm at a loss to there original sound. If you can manage to get them even close to sounding like mine you'll be shocked to death at the raw power these old girls can muster up . Mine can peel paint ( almost ) hooked into the lascalas or k-horns, makes my 380wpc SS rotel sound like dirt. Now i'm not putting down the rotel this amp is a real beast at almost 100 lbs and bigger than most small tv's. But the sound of tubes is totaly different indeed. Quote Link to comment Share on other sites More sharing options...
AnalOg Posted May 19, 2003 Author Share Posted May 19, 2003 I installed the dual bias mod & 10ohm resistors, I set the bias at each pot to 500 mv. Tom Quote Link to comment Share on other sites More sharing options...
NOSValves Posted May 19, 2003 Share Posted May 19, 2003 Tom, Looking at your sig tells me a interesting thing !! You need more speakers ! Quote Link to comment Share on other sites More sharing options...
AnalOg Posted May 19, 2003 Author Share Posted May 19, 2003 Looking at your sig tells me a interesting thing !! You need more speakers ! -------------------------------------------------------------------------------- I WISH!! Tom Quote Link to comment Share on other sites More sharing options...
AnalOg Posted May 19, 2003 Author Share Posted May 19, 2003 This was a dual bias mod purchased from Triode Electronics. That is what they specified. Do you have any suggestions? Thankx Tom Quote Link to comment Share on other sites More sharing options...
AnalOg Posted May 21, 2003 Author Share Posted May 21, 2003 Ok guys here's the deal. My Foreplay's stock output impedence is 470k, my Dynaco Mark III stock input impedence is 470k. I own several amps and the bottom end is missing from the Dynaco's in comparison to my other units. I have done the mods on the Dynacos and with each it has gotten better, but still its not all there. The Paramours I built have a stock input impedence of 270k, the Foreplay & Paramours were designed to work together, as they are both Bottlehead's DIY kits. What I did was drop the input impedence of the Dynacos to 270k. And made a world of a difference in the bottom end. Although I think I sacrificed some top end and the bottom end sounds somewhat "loose". My question is, is there a formula to follow in regards to matching impedence, in order to eliminate the guessing game, or do I have to submit myself to "resistor rolling". Tom Quote Link to comment Share on other sites More sharing options...
NOSValves Posted May 21, 2003 Share Posted May 21, 2003 Ok guys here's the deal. My Foreplay's stock output impedence is 470k Don't you mean 270K above ?? Quote Link to comment Share on other sites More sharing options...
AnalOg Posted May 21, 2003 Author Share Posted May 21, 2003 My oppologies on the mis information. Its actually more like 3200 ohms. I don't claim to be a techy kind of person. I looked at the schematic and read the resistor at the output rca to ground, it was 470 ohms. I was informed by Doc at Bottlehead that it's more like 3200 ohms. I don't know how they come up with that but thats what it is. Tom Quote Link to comment Share on other sites More sharing options...
greg928gts Posted May 21, 2003 Share Posted May 21, 2003 I have 2 Dynaco Dynakit Stereo 70 amplifiers. Are these anything like the ones you're talking about here? I don't see Mark II or Mark III anywhere on them, at least on the outside. Someday, I was going to ask someone about turning these into mono amps, and if possible, triode mono. I know just enough about this stuff to be dangerous. Greg Quote Link to comment Share on other sites More sharing options...
AnalOg Posted May 21, 2003 Author Share Posted May 21, 2003 greg, You have the stereo version of what I have. I believe you can run the st70 in mono and have one for each channel,(I'm sure someone will correct me if I'm wrong). That would provide for a better sounstage do to the fact that each channel has its own power supply. The out put tube compliment is also different, yours has el34, and the mark III has 6550 or kt88 whichever you prefer. Tom Quote Link to comment Share on other sites More sharing options...
NOSValves Posted May 22, 2003 Share Posted May 22, 2003 The Stereo 70 is not a Stereo version of the Mark III . It is a Stereo version of the Mark IV or vice versa. It can not run 6550/KT88's the Power supply and OP Transformers are not robust enough. However they are great EL-34 amps ! I wouldn't personally bother making them mono power amps. I would sell them on Ebay and take the money and buy some Mark III's designed as mono amps myself. You should be able to get $300 a piece for them if there in descent original shape. Craig Quote Link to comment Share on other sites More sharing options...
AnalOg Posted May 22, 2003 Author Share Posted May 22, 2003 The Stereo 70 is not a Stereo version of the Mark III . It is a Stereo version of the Mark IV or vice versa. I new someone would correct me if I'm wrong. Thankx Craig! Tom Quote Link to comment Share on other sites More sharing options...
sunnysal Posted May 22, 2003 Share Posted May 22, 2003 greg/craig, I seem to remember an article that mentioend that an st-70 could be run in mono quite easily, just switch the fornt mounted stereo switch to mono, use any input and....I do not remember what to do at the outputs...so 2xST-70s would make monoblocks...was it glass audio? VTV? the triode strapping mod can be dond quite easily (I loved the effect it had on the sound of my MkIVs, which is quite similar to your ST-70) on the ST-70 if you need instructions they are posted all over the web. joe curcio has them available for free download. (note: see page 12 of the manual on-line at http://www.curcioaudio.com/st7_mnl.pdf ) it talks about setting for mono...good luck! tony Quote Link to comment Share on other sites More sharing options...
AnalOg Posted May 22, 2003 Author Share Posted May 22, 2003 Again, Correct me if I'm wrong. I don't believe Craig meant that it wasn't possible, just that sonically it would be more beneficial to own the MarkIII's over the ST70 for the monoblock configuration. Tom Quote Link to comment Share on other sites More sharing options...
sunnysal Posted May 22, 2003 Share Posted May 22, 2003 yes I guess that is what craig meant, but I think the dollar value you would lose in the "sell the st-70 buy some mkIIIs" would be onorous. since you have two ST-70s I suggested trying them as mono-blocks, you will get many of the benefits of the monoblock configuration without making the investment. if you remain unsatisfied or curious after that step THEN you consider a sell/buy process. my two cents. regards, tony Quote Link to comment Share on other sites More sharing options...
AnalOg Posted May 22, 2003 Author Share Posted May 22, 2003 I follow your train of thought, and yes it makes sense to give it a go. Although you can't A/B to see what you would perfer, of course, unless he has some Marks on loan from someone. The buy/sell process would leave him about even as per what ST70 and mark III's are going for on ebay. Of course the only down fall would be that he can't split up the Marks as individual systems like the ST70, if he chooses. I can't speak for the ST70, but the Mark's put out some serious dynamics & don't choke up when driven hard. And on the other hand at low volumes they give you the warm intimacy of SET,(I know I'm going to get hosed for that statement). This I can speak from experience with all the mods in place and strapped in triode mode. All these statements of course are my personal observations based on my limited experience! Tom Quote Link to comment Share on other sites More sharing options...
sunnysal Posted May 22, 2003 Share Posted May 22, 2003 no hosing BUT, there is a real difference to be heard between these nice PP amps that use the EL34, EL84, KTXX, 6550, etc. and the SETs and any DHT (300b, 2A3, 45) based amps. just a little more of the tube goodness I would say. I was afraid of the SET not having enough "umph" for me so I went with a DHT PP design and am quite happy, it is a decernable step up from my EL34 PP...I will not deny that a tricked out dynaco MkIII or MkIV is tremendous value for the money and gets you 90% of the way to the famous DHT magic. but I would look to spend less than $750 all in for that option or else you are getting close to the "big tube" area and could consider some 300b, 2A3 based amps...regards, tony Quote Link to comment Share on other sites More sharing options...
Marvel Posted May 22, 2003 Share Posted May 22, 2003 Since I don't have much moola, having one ST70 in hand is better than me trying to sell it and get something else. I've done that with guitars over the years and wish I still had what I sold. Hopefully, I'll have my ST70 up and running before too long. It is a sweet sound. Sunnysal, I'll be very nosey and ask what price range your PP 2A3 was. All those interstage transformers instead of caps. Wow! Marvel Quote Link to comment Share on other sites More sharing options...
sunnysal Posted May 22, 2003 Share Posted May 22, 2003 well, it was less than $2,000...a screaming bargain for what I got. Built like a $5,000 amp without a doubt (put some WBT spades on it and pretty bell ends and someone could charge twice that!) ...regards, tony Quote Link to comment Share on other sites More sharing options...
NOSValves Posted May 22, 2003 Share Posted May 22, 2003 Sunny, I am going to have to chime in on your statements here. While I'm absolutely shure that your new amp sounds spectacular ! To some people it may not have enough umph 10 watts is 10 watts. I for one could never live with 10 watts running a full range speaker and be happy. I can barely handle 20 watts without feeling short changed at times . One persons "Big Tube goodness" is not always anothers ! We all have are wants needs and preferences. Also 1K spent on a nice set of Mark III's are a long way from 2K for 90% of the sound and Headroom to spare. Craig Quote Link to comment Share on other sites More sharing options...
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