Rocky Rides Again
- Cressy Snr
- Amstrad Tower of Power
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#1 Rocky Rides Again
Hi Guys
Just finished another Rocky amp; this time it was for our Anthony.
He'd been mithering for a valve amp for the last few months. I told him that if he wanted one then there were a few conditions:
He was going to have to put in quite a lot of of the work himself, ie ordering the major bits and paying for them.
He was going to have to design and build the case, mount all the transformers, valve sockets, speaker outlets, mains cable and input sockets, then I might think about wiring it all up for him.
I thought all these conditions would slow him down a bit but no. He ordered all the bits from Philip at Bluebell and last week presented me with a fully fitted out chassis. It is wired up and running in on the bench as I write this and sounding pretty darned good.
The transformers are a Hammond 260G for power, a pair of 125GSE outputs and a 193J choke, plus a trio of Hammond potting boxes. The choke is inside the case, out of sight.
Valve complement is a pair of RCA VT229 (6SL7) and the ubiquitous Electro-Harmonix EL34s. He has a Sovtek GZ34 rectifier valve on order cos he ain't having that NOS Mullard I lent him to get the amp going.
I reckon he has made a great job on the looks. Wouldn't be my first choice for our living room but it fits his home environment perfectly.
The finished chassis looks like a cross between Darth Vader and an Aztec temple but IMO the visuals hang together very well.
Steve
Just finished another Rocky amp; this time it was for our Anthony.
He'd been mithering for a valve amp for the last few months. I told him that if he wanted one then there were a few conditions:
He was going to have to put in quite a lot of of the work himself, ie ordering the major bits and paying for them.
He was going to have to design and build the case, mount all the transformers, valve sockets, speaker outlets, mains cable and input sockets, then I might think about wiring it all up for him.
I thought all these conditions would slow him down a bit but no. He ordered all the bits from Philip at Bluebell and last week presented me with a fully fitted out chassis. It is wired up and running in on the bench as I write this and sounding pretty darned good.
The transformers are a Hammond 260G for power, a pair of 125GSE outputs and a 193J choke, plus a trio of Hammond potting boxes. The choke is inside the case, out of sight.
Valve complement is a pair of RCA VT229 (6SL7) and the ubiquitous Electro-Harmonix EL34s. He has a Sovtek GZ34 rectifier valve on order cos he ain't having that NOS Mullard I lent him to get the amp going.
I reckon he has made a great job on the looks. Wouldn't be my first choice for our living room but it fits his home environment perfectly.
The finished chassis looks like a cross between Darth Vader and an Aztec temple but IMO the visuals hang together very well.
Steve
#2
Cool, its the retro family, you do the 50's, Anthony seems to be aiming at the 70's. All it needs is a trimphone on one side.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
- Cressy Snr
- Amstrad Tower of Power
- Posts: 10582
- Joined: Wed May 30, 2007 12:25 am
- Location: South Yorks.
#3
Don't set him off NickNick wrote: All it needs is a trimphone on one side.
#4
Here you go...
And I had forgotton how annoying the dial sound was...
http://www.robertopiecollection.com/App ... mphone.wav
And I had forgotton how annoying the dial sound was...
http://www.robertopiecollection.com/App ... mphone.wav
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
- cressy
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#5
another little update on the amp, iv done sod all to it since it was built but now its burned in i dont think ill be bothering with anything else. the only change made was the rectifier to a jj instead of the mullard and apart from the mains transformer running a little hotter the sound is to my ears alot better. it has alot better defenition across the bass and a little better midrange. the treble seemsa little less defined but the pros outweigh the cons. im not a big fam of mullards really, every single one ive heard, ive heard better from something else. (please dont hit me!!!!!) they just arent my cup of tea.im looking at maybe some kt77s and possibly some 6550s to try but the 6550s might not fit as the bases are too colse together for the envelope. any suggestions? id love to try somethig else just to see, but all im after really is abit more poke as the phono stage gets mighty close to clipping sometimes althiugh some 12:1 step ups instead of 10:1s will cure this. kt 66s 77s and 88s will drop in ok by the looks of the circuit with maybe a change to the cathode resistors (ive been reading morgan jones but perhaps a little knowledge is a dangerous thing!) but i havent heard or cant recall any of these. since im pissing about with the lenco at the mo simple plug im mods are the way for me so what do folks recommend? any help gratfully apreciate folks.
- Cressy Snr
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#6
Anthony!
Stop swearing and I'm not referring to your dislike of Mullards
Stop swearing and I'm not referring to your dislike of Mullards
- cressy
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#9
just another update on the amp, ive dropped in a pair of matched jj kt77s and i must say that i wasnt expecting quite such a dramatic difference. they are really good! they seem to improve in an el34 in every aspect. they are brand spankers so need burning in properly for the next few days but theres a real improvement straight out of the box. i havent heard any before but apparently the amp design is meant for the kt77 so i thought id try them. ive been after some 6550s at a reasonable price for a while but these are bloody good tubes so i might put that on hold for a while as it means a new top plate as the sockets are too close together at the mo for the envelope on the 6550s. very impressed so far though! only problem is i still cant find a trimphone!
- cressy
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#10
just had a set of el37s in it.................. bloodyell the kt77s got pasted. looks like i'll have to hunt a set down as i cant have/afford the ones that were tried in it as theyre being sold. 6l6s seem fairly plentiful but i havent heard them. the gave the amp a right kick up the bottom end and seemed to grab the metronomes by the scruff of the neck and drive them. this was with them in from cold and only in for 20 mins. bugger, thats something else to save up for! anyone got any? (crosses fingers and hopes theyre not too dear if someone has!)
- cressy
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#11
well i got a set of nos philips 6l6's and im rathr happy with them, a little less hum than the 77s and a little more bottom end than the jjs too. a good improvement but i still want some 37s! these'll do very nicely for now as they seem to be lossening up abit and filling out. another week and we'll see what to make of them then.
#12
Very nice work there Cressy.
How do you build them so quick?
I've been building my 6em7 integrated amp now for what seems ages. But then I am presently hamprered with the use of only one leg and a pair of crutches. Well that's my excuse.
How do you build them so quick?
I've been building my 6em7 integrated amp now for what seems ages. But then I am presently hamprered with the use of only one leg and a pair of crutches. Well that's my excuse.
- cressy
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#14
just swapped out the rca 6sl7s for a pair of golden dragons, what a difference!, they added a shedload of body to the amp and better frequency extremes. seems to have an extra octave at the bottom end! cant have obviously but its so much tighter and better defined. this amp is a great plaything!
- cressy
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#15
has anyone had any experience with the 5b255m beam tetrode at all? i ran across it looking for the curves for the 6l6s. it looks almost identical. the only info i could get was that its an 807 type without a top cap. someone on an australian forum said it was a drop in for the 6l6. would it be worth getting a pair to try?