Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Sesh on October 20, 2020, 01:45:00 am
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Hi there - long time lurker, first time poster.
I'm acquiring a Hagström 310, a Swedish tube amp apparently identical to an old Mullard tube amp kit. Has a strange ecll800 tube. Schematic
https://edgaraudio.se/tubes/Hagstrom/Renovera310-filer/310.jpg
It very likely needs a cap switch,and while I'm in there I wanted to do some mods. There's already a decent Swedish site with a few mods https://edgaraudio.se/tubes/Hagstrom/Renovera310.htm
But I wanted to do something more radical as apparently it in stock form doesn't overdrive particularly well which is what I crave a small amp that does!
I particularly love the sound of old Valcos. The Hagström shares the two Ecc83s in the preamp with the 1624t, and like the Supro it has tremolo, so I thought that'd be a good "model"amp.
1624t schematic here https://el34world.com/Forum/index.php?action=dlattach;topic=22101.0;attach=65765;image
Any ideas for mods that'll get me closer to the Supro?
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My first thought when I viewed your post was, how strange could that tube be? But vert der ferk, pretty darn strange, and rare, and expensive. But if that ecll800 is ok, I would want to get it working stock first, just to satisfy my curiosity and decide if I wanted to perform major surgery, such as adding a tube socket or two. If you did not do a search here yet, you will find two threads on this tube, and one of them has lots of suggestions for tube combinations to use with that iron. I'd want to keep it close to stock, but that's because I like unusual things, and that may not align with your main goal, so I'm not suggesting a path. The good news is that looking at the article in your link, there is lots of room in the chassis, and the circuit is not complex (but a lot is happening inside that ecll 800 - a phase inverter and two outputs.) BTW, The Google translation to English of that article is hysterical; valves are pipes, schematic is schedule, grids are grilles, and that amp has a tailpipe.
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since ECLL80 is so scarce, i would rewire and add 6BM8/ECL82 with the triodes wired as a paraphase inverter. from what i've heard from youtube clips, those are decent sounding little amps - the cathode coupled tremelo ckts. sound really sweet. if yours is working, i'd hesitate to hack as it seems to have some collector value?
--pete
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In the words of Colonel Clink, "I know nothing" and I didn't sleep at a Holiday Inn Express last night. However, a few minutes ago, I did run across this interesting Swedish website that specializes in vintage tube gear and guitar amps. They have some hagstroms listed. Perhaps they would be a source of info or could help you find the rare tube or a substitute?
I stumbled across it researching 6AK5's as pentode preamps and supposedly they have some patent on a variable gain pentode hookup that allows you to seamlessly transition a pentode from triode mode to pentode.
They call it TULP. " All TULP circuits are continously variable from Triode to Ultra-Linear to Pentode, stage- gain 29-54dB. From 12AY7 to 6267 by turning on a knob"
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In the words of Colonel Clink, "I know nothing"
Uh, that would be Sgt. Schultz. :wink:
They call it TULP.
Merlin calls it Morph...
http://www.valvewizard.co.uk/ef86pcb.html
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:worthy1:I got my German's confused this AM. I meant the fat one. Not the myoptic one...Although I understand Klink was actually Jewish. Need another cup. :BangHead:
Interesting on the MORPH circuit. Thanks for sharing.
Sorry for the hijack/misdirect Sesh.
Back to discussing the Swedish amps ( Blencowe is close though being Norse)
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Hi again
I dropped buying the Hagström the first time around, as I was short on dough at the time.
It's still for sale for 160 euros, can probably knock a little off the price.
So to answer the concerns put forth in the thread: They have little to no collector value here in Denmark (neighboring Hagströms native Sweden), the stock speaker is utter crap and in stock form it's not really well-suited to guitars. Also the ECLL800 tube apparently means it can't be overdriven properly. The tremolo is supposedly pretty good, tho. In otter words, I have no woes modding it extensively.
So since last time I researched on how to hotrod the amp. I saw in another thread where someone had an OT made for ECLL800, and someone suggested using it for an output of ECL82/6BM8 as in the 50s Gibson GA-8, Univox U45 or early Watkins Westminster. All cool tone machines from the videos I've seen - especially eyeing the Gibson.
Now I should say this will be my first tube undertaking, so now's the time for sagely advise!
I've, however, spent the pandemic building 20 something guitar pedals, watched Uncle Doug videos and read up on Robrobinettes, so I at least know the theory, tube safety etc
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You built 20+ pedals! Jeez, I thought I was doing well with amps, rebuilds, and PA conversions during the pandemic. The thread you are referring to has lots of great info, as well as a funny quote from PRR about Corgis and Beagles. I have a Gibson GA-8T, that's the one with the 6BM8s, that I rebuilt stock. I think they are wonderful sounding amps. I understand the U45 is too, and Richard Goodsell liked the sound of those enough to create his own version.
So did you buy the Hag, or still thinking about it?
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You built 20+ pedals! Jeez, I thought I was doing well with amps, rebuilds, and PA conversions during the pandemic. The thread you are referring to has lots of great info, as well as a funny quote from PRR about Corgis and Beagles. I have a Gibson GA-8T, that's the one with the 6BM8s, that I rebuilt stock. I think they are wonderful sounding amps. I understand the U45 is too, and Richard Goodsell liked the sound of those enough to create his own version.
So did you buy the Hag, or still thinking about it?
I've placed a bid of a 135 euros, waiting for the seller to respond.
Haha, let's just say there were a lot of fuzz pedals I've been GAS'ing over through a couple of years - and then I discovered DIY-electronics, namely veroboard layouts. The idea of making a 300 euro pedal for a 30 enticed me to a degree that I've become obsessed. That plus unemployment during the pandemic.
Now I've gotten the same bug for amps (I got a thing for off-brand local and European amps - already own a Selmer Treble & Bass Mk. II). Logical next step, right? And all my research has pointed me towards this forum.
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I like the looks of that little amp. If I could find spare tubes for it, I would fix it just as is and evaluate it. If no tubes available, I'd strip it and build a small amp of my choice in it, even if I had to buy new transformers.
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I like the looks of that little amp. If I could find spare tubes for it, I would fix it just as is and evaluate it. If no tubes available, I'd strip it and build a small amp of my choice in it, even if I had to buy new transformers.
I like the looks as well, and even if it seems unrescuable, 160 euros for a well-made, "naturally relic'ed" cabinet and chassis is fair, I guess.
Well, I'll wait and see if it works. The owner says so, though only one of the channels.
Perhaps the mods specified here (https://edgaraudio.se/tubes/Hagstrom/Renovera310.htm) and a new speaker could make it a decent pedalplatform, if it such a clean amp as people say.
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The owner says so, though only one of the channels.
Easy fix if that's true.