www.wavebourn.com

We create creativity!
It is currently Sun Jul 22, 2018 9:11 pm

All times are UTC - 8 hours [ DST ]




Post new topic Reply to topic  [ 2 posts ] 
Author Message
 Post subject: SE Guitar AMP with existing OPT
PostPosted: Mon Mar 28, 2011 3:42 am 
Offline

Joined: Fri Mar 19, 2010 8:59 am
Posts: 21
Hi!

Looong time ago, I promised a friend of mine I'll build a small practice guitar amp for him.

I Live in Spain and power transformers and OPT are wayy expensive here, buying them overseas (e.g. Edcor) adds a lot in terms of shipping.

I recently got a couple of Old Telefunken SE OPTs from Germany, theoretically intended for use for EL95, 12K:4 Ohm, they were cheap and rumor is they sound really good.

My first idea is trying to use one in the guitar amp, with a 6P15P and two 8 Ohm "Full Range" (70Hz-17kHz) 96dB Beyma speakers in parallel (hence 4Ohm) and relfected OPT impedance of 6K?

I thought on using the same AX84 P1 amp circuit, but using tube rectifier or hybrid, 6N2P-EV instead of the 12AX7 (rewiring, of course) but instead a EL84 / 6P14P use a 6P15P which AFAIK has higher Anode resistance and approaches the more "theoretical" 10:1 in terms of Anode Resistance/Primary Impedance OPT ratio .

However, I understand guitar amps are part of the instrument, and as such must distort; as long as these distortions are euphonic.

Is there any way I can predict which kind of distortions? which route of experimentation would you seek? Paralleling more speakers (they're rather good and cheap, 8") using just one speaker and other means? I understand I must seek 2nd order distortion?.

I also got a suitable power transformer, with secondaries intended for "el84 SE use": 320V HT, 6.3V and would prefer to use one of these...


 
 Profile  
 
 Post subject: Re: SE Guitar AMP with existing OPT
PostPosted: Mon Mar 28, 2011 7:46 am 
Offline
Шаман, типа...

Joined: Tue Feb 10, 2004 12:30 pm
Posts: 7316
Location: Pleasant Hill, California
Hi Pukkita;

if you connect a pair of 8 ohm speakers in parallel you still would have 4 Ohm and 12 Ohm reflected.

For higher 2'nd order harmonic I would probably go with triode mode, with lower plate voltage and lower load resistance. But 12K and 400-450V B+ in pentode with 200V on G2 may sound nice as well! For a sag/compression you should select proper value of screen grid voltage divider and the value of the capacitor shunting it.

For the rest of you project; yes, 6N2P will be fine there instead of 12AX7.

Anatoliy

_________________
А женщина даже в мужской рубашке выглядит гораздо приличнее, чем мужчина в женских колготках! Be-be-be!


 
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 2 posts ] 

All times are UTC - 8 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB © 2002, 2006 phpBB Group
[ Time : 0.033s | 15 Queries | GZIP : Off ]