128x128

donsachs

Responses from donsachs

300b lovers
@charles1dad I am sure it is a great amp.   Looks like my usual sources have 6EM7 for $15 a tube or so.  If you love the amp, you probably already have bought a few for the drawer.  If run conservatively I would expect them to last a long time, s... 
300b lovers
@atmasphere the ST70 power transformer spec was allegedly 2 x 6.3 V windings @5A each.   Pair of el34 is 3 A, even a pair of 6sn7 is only 1.2A, so that should be only 4.2A.  Should be safe   
300b lovers
@atmasphere Hi.. you are only running 3 6sn7 tubes.   Input tube and then a long tailed pair driver on each side using a single 6sn7....  
300b lovers
@atmasphere Actually, I have rebuilt a few ST-70.   I agree, the rectifier is inadequate, but so is the driver section, which is at clipping at or just before the output section clips.   I have heard a couple of drop in boards and the octal versio... 
300b lovers
The HK Citation gear was the most razor flat sounding, and the Fisher receivers were actually quite good.   The Scott gear was also quite good, and my favorite small integrateds were the Sherwoods.   Their little EL84 based integrated was quite go... 
300b lovers
I rebuilt a number of classic mac tube amps when I was restoring vintage gear.  They all sound very nice, but the mac house sound is a bit soft to my ear.  Sort of on the warm side.  Pleasant sounding, but not the absolute last word in detail.  Th... 
300b lovers
Lastly, I will say that internet forums are both a blessing and a curse.  There are people who tout one amp topology over another, or whether they prefer SS or tubes, or interstage transformer coupling over LC or RC, etc...   When you read these t... 
300b lovers
Again, basically what Lynn said.   At each stage of the project whether in the preamp or amps I discussed the exact parameters and even shared the relevant part of the circuit with Dave Geren at Cinemag, who is a very experienced master winder of ... 
300b lovers
Basically what Lynn just said.  Once you hear it you cannot go back.  Even the best caps cannot touch it.  Now, that said, you will not hear this if the rest of your system is not up to the task.  You put a $500 DAC in front and a mediocre preamp ... 
300b lovers
@eddie138 Thanks so much for chiming in.  Really interesting post and the economics are of course as you stated.   It is not like getting a custom capacitor made where you only have to have 100 of them for an order.   I guess that explains why man... 
300b lovers
Funny you talk about filament sag.  I used to restore tons of vintage tube amps when I collaborated with Jim McShane.  So I worked on many amps that used the EL84 type tubes.   There is a Russian variant that is quite a good sounding tube and you ... 
300b lovers
nice wish list....   unfortunately, the power race is on to build even more powerful KT88 to get KT120 and now KT150.   They generate more watts if the amp can be biased to run them, but they don't sound as good as a good KT88.  I think it is the ... 
300b lovers
Yes, you do star grounding, and you always do "sub" stars for each stage.  At least that is how I do it.....  
300b lovers
if you can fit a toroid in there, then look at the antek site.  They have small filament transformers and may have what you want.  AN0205 is 25VA with dual 5V windings so will give you 2.5 A x 2.   They are fine for what you want.  they also sell ... 
300b lovers
Much appreciated.  I will investigate further.  Vinnie is a well respected designer of note.   cheers, don