just finished my first diytube 35 and im very pleased! got the board from a member (thanks!) and i used all parts that i had on hand already, making for wallet-friendly project. no sacrifices to the spouselord for this one!
i used some uos sockets i pulled from some reel-to-reels, coupling caps from a tek scopes carcass i received, old stock 1% mepco and IRC resistors that i got for free. quad of sylvania black plates labeled baldwin.(yes, from an organ, and they all have yellow paint on the tips indicating testing for microphonics i assume?)
so, i have this pair of acrosound transformers that ive been staring at for a year and havent touched. theyre TO-300's that are 6.6k p2p, 43% taps @20watts. close enough right? well it turned out great! speakers are seas aluminum zaph designs, the bookshelf L18 one. not very sensitive but the mesh well in my small room. thanks for the great board shannon! im sure this wont be the only one in my house for long.
WOW!!
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by Ty_Bower » Mon Apr 13, 2009 9:49 am
I used a pair of Hammond 1620 output transformers on the first ST35 I built. They are also rated 6.6k P-P. The amp turned out very well, and I was pleased with the performance of the Hammonds.
A few things I noted about the 1620 - the amp seemed to have much higher overall gain than a similar amp where I used a real Z565 transformer. Perhaps some tweaking of the NFB resistance might be in order. I also noticed the 1620 distorted fairly early on at the low frequency end. I figured they were only good for about 4.5 watts at 20 Hz before things started to get really ugly. I didn't notice any problems from about 50 Hz up, though. Perfectly serviceable transformers, and the price was certainly right.
A few things I noted about the 1620 - the amp seemed to have much higher overall gain than a similar amp where I used a real Z565 transformer. Perhaps some tweaking of the NFB resistance might be in order. I also noticed the 1620 distorted fairly early on at the low frequency end. I figured they were only good for about 4.5 watts at 20 Hz before things started to get really ugly. I didn't notice any problems from about 50 Hz up, though. Perfectly serviceable transformers, and the price was certainly right.
"It's a different experience; the noise occlusion, crisp, clear sound, and defined powerful bass. Strong bass does not corrupt the higher frequencies, giving a very different overall feel of the sound, one that is, in my opinion, quite unique."
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Ty_Bower - KT88
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by Shannon Parks » Tue Apr 14, 2009 6:00 am
Glad to see another ST35 take life out there! 
I wish I had tweaked the ST35 for the 1620s. I'll have to refer back to the transformer tests I ran awhile back and see if the data shows me anything.
I wish I had tweaked the ST35 for the 1620s. I'll have to refer back to the transformer tests I ran awhile back and see if the data shows me anything.
- designer of fine tube audio gear at (((parks audio)))
- founder and admin of the diytube forums
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Shannon Parks - Site Admin
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by Ty_Bower » Tue Apr 14, 2009 6:24 am
Be careful what you wish for. Wanna borrow a set of 1620 for a while? They've even got connectors crimped on the ends of the leads already...
"It's a different experience; the noise occlusion, crisp, clear sound, and defined powerful bass. Strong bass does not corrupt the higher frequencies, giving a very different overall feel of the sound, one that is, in my opinion, quite unique."
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Ty_Bower - KT88
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- Joined: Wed Mar 21, 2007 2:50 pm
- Location: Newark, DE
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