FlMike said:
You must be referring to the neat little phase-splitterless PP amp. R3 is the tone control, it & the cap in series with it could just be eliminated. R5 is the volume control, it could be replaced with a fixed R.
dave
Way back when Mullard produced a very good book on audio with circuits. If I remember correctly there was a 5-10 amp and a 10-10 amp. These used EL84's and EF86's. From What i remember they were very popular and gave a good sound.
Does anyone have any info on these amps or if the book is still available.
Many thanks
Phil.
Does anyone have any info on these amps or if the book is still available.
Many thanks
Phil.
Simplest 6BQ5 SE
Is this the Tubecad page you guys were looking for before?
http://www.tubecad.com/september99/page11.html
Simple. But I personally prfer the 6W compact Yves posted. The output stage of the amp I'm currently building is similar in topology.
Cheers
Is this the Tubecad page you guys were looking for before?
http://www.tubecad.com/september99/page11.html
Simple. But I personally prfer the 6W compact Yves posted. The output stage of the amp I'm currently building is similar in topology.
Cheers
i am interested in building this
http://www.triodeel.com/compact.html
the opt xformers i have are from a 6bm8 amp ani i dont know any of the specs on them. what are the chances that it will work out ok? anyone know of a similar circuit that uses 6bm8"s instead of 6bq5's. this is my first project and everything else is done expect for wiring. you can see what i have done so far in this thread.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=1782
cheers, mike
http://www.triodeel.com/compact.html
the opt xformers i have are from a 6bm8 amp ani i dont know any of the specs on them. what are the chances that it will work out ok? anyone know of a similar circuit that uses 6bm8"s instead of 6bq5's. this is my first project and everything else is done expect for wiring. you can see what i have done so far in this thread.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=1782
cheers, mike
Hi Mike,
It's hard to say whether your transformers are suitable until you know the turns ratio. Its very easy to measure. I've never used 6BM8s.
First, turn off the amp and make sure it is discharged. Desolder the B+ and the leads to the 6BM8 plates.
Next get a low voltage AC transformer, say 3V and place it across the 8R taps. Measure the ACV with a voltmeter across the 8R taps. Then measure the ACV across the primary, plate-to-plate. Divide the primary ACV by the secondary ACV. This gives you your turns ratio. Square this number and then multiply it by 8 and you have the primary impedance plate-to-plate.
The spec in the article calls for 8kR plate-to-plate. My trans is 7kR and even though my horns should be above 8R, I think 7kR should be OK. The Dynaco ST35 was 7.1kR.
HTH
Brett
It's hard to say whether your transformers are suitable until you know the turns ratio. Its very easy to measure. I've never used 6BM8s.
First, turn off the amp and make sure it is discharged. Desolder the B+ and the leads to the 6BM8 plates.
Next get a low voltage AC transformer, say 3V and place it across the 8R taps. Measure the ACV with a voltmeter across the 8R taps. Then measure the ACV across the primary, plate-to-plate. Divide the primary ACV by the secondary ACV. This gives you your turns ratio. Square this number and then multiply it by 8 and you have the primary impedance plate-to-plate.
The spec in the article calls for 8kR plate-to-plate. My trans is 7kR and even though my horns should be above 8R, I think 7kR should be OK. The Dynaco ST35 was 7.1kR.
HTH
Brett
Mind sharing your circuit?
Brett,
Would you be so kind to share your
output stage circuit that is similar to the
6W amp?
I wonder why that differential pair
output state topology
is not so common - perhaps it is the need to
get equal currents thru both tubes?
rgds
Yv
Brett,
Would you be so kind to share your
output stage circuit that is similar to the
6W amp?
I wonder why that differential pair
output state topology
is not so common - perhaps it is the need to
get equal currents thru both tubes?
rgds
Yv
FlMike said:
6BM8 (ECL82), ECL86, EL95, 6BQ5(EL84) are all fairly close in terms of their OPT requirements so go for it.
dave
About the above schemi posted by Tomcat, there is a pot in the feed back loop, what does this pot do? and what type/kind of output tranny should be used??
Yep... Planet 10 is right, the 6bm8 output tranny is close enough to the 6bq5. Go For It...
tomcat
tomcat
RMS: I'm not sure about the pot in the NFB loop only to theorise that a) to be able to vary the amount of NFB to taste (it does make a diff to the sound), or b) to adjust to make up for the parametric spread in components and prevent oscilation, as whoever at the time and just as now, would not be able to access the exact same components, so this feature allows for that methinketh humbly....
tomcat🙄
tomcat🙄
tc & p10 , thanks for your help and as soon as the finnish dries on the cabinet i am going to start wiring it.
cheers, mike
cheers, mike
No Worries Mate!,
I have a few others in my files if you or anyone else is interested...
tomcat😉
I have a few others in my files if you or anyone else is interested...
tomcat😉
RMS,
I have had in my house on lone a pair of the Mullard 3 monoblocks and got wonderfull sound from them. There was no pot in the feedback circuit and a volume pot had been installed between the input jack and the 6267/EF86. I don't know how good your opts are but if you have the bandwidth this is a nice amp. I was driving 92db efficient speakers and got lots of volume before they started to clip the amps.
I have had in my house on lone a pair of the Mullard 3 monoblocks and got wonderfull sound from them. There was no pot in the feedback circuit and a volume pot had been installed between the input jack and the 6267/EF86. I don't know how good your opts are but if you have the bandwidth this is a nice amp. I was driving 92db efficient speakers and got lots of volume before they started to clip the amps.
Would this be a suitable OPT for a small SE EL84 amp?
http://www.demostenes.no/endr1be.asp?Kode=3956
I´m going to build my first tube amp and I´d like to start with something cheap/simple. I´ve almost decided to go with EL84 but I´d like a little more power than a single EL84/channel can manage. Would it be just as simple (circuit wise) to use 2 EL84 tubes per channel?
/Erik
http://www.demostenes.no/endr1be.asp?Kode=3956
I´m going to build my first tube amp and I´d like to start with something cheap/simple. I´ve almost decided to go with EL84 but I´d like a little more power than a single EL84/channel can manage. Would it be just as simple (circuit wise) to use 2 EL84 tubes per channel?
/Erik
That store also have CHEAP Sovtek EL84/6BQ5 tubes at less than US $5! That should be great to use when buildning my first amp where i want everything to be as cheap as possible.
They also have another Sovtek EL84/6BQ5 that cost about $9.
/Erik
They also have another Sovtek EL84/6BQ5 that cost about $9.
/Erik
planet10; my amp is finished!
Hey Dave, thanks to your help my amp was a success!
I thought everyone should know that I built that first schematic at the begining of this thread and its working fine. For the most part all the values for the ressistors and caps that I used are fairly close if not the same to what is in the map. Though I did use an extra cap in series in the first filterstage to take the surge of the solid state rectifier diodes. At first testing no sound at all, then I cliped the negative feed back lead that goes to ground and it worked and I cliped the other feed back lead and there was no difference in sound so that is all gone now. Its also plenty loud enough and drives a 12" speaker very clearly.
Here are the test results:
B+1=331VDC, B+2=262VDC, B+3=235VDC
EL84= pin9=261V, pin7=311VDC bias=47mA, pin3=6VDC
Hey Dave, thanks to your help my amp was a success!
I thought everyone should know that I built that first schematic at the begining of this thread and its working fine. For the most part all the values for the ressistors and caps that I used are fairly close if not the same to what is in the map. Though I did use an extra cap in series in the first filterstage to take the surge of the solid state rectifier diodes. At first testing no sound at all, then I cliped the negative feed back lead that goes to ground and it worked and I cliped the other feed back lead and there was no difference in sound so that is all gone now. Its also plenty loud enough and drives a 12" speaker very clearly.
Here are the test results:
B+1=331VDC, B+2=262VDC, B+3=235VDC
EL84= pin9=261V, pin7=311VDC bias=47mA, pin3=6VDC