Hiwatt DR103 Owners: school me on tubes

saltyj

Member
Messages
155
Please! I recently got a ‘77 and it’s full of random tubes, nothing nice. What’s the best setup for current production tubes? Vintage? I’m also a bit confused about the preamp tubes, I know they’re 12ax7 but do I need specific ones depending on the slot? I’ve owned a Bassman for the past 15 years and never had to deal with tubes before, surprisingly. Thanks!
 

Echoplexi

Gold Supporting Member
Messages
12,230
I’m running new Svetlana el34s and old Mullard 12ax7/12at7s in my 74 Hiwatt.

I’m not completely sold on the Svetlanas, but they have been solid and reliable.

The best would be all nos Mullards, but that would be very costly (I have done it, but I only need a pair of power tubes). New production is a matter of preference really. I’ll also be checking in to see what people say.
 

KBN

Silver Supporting Member
Messages
1,421
First, a few caveats: I have a Reeves Custom 50 and not a Hiwatt, I'm not trying to sound like Gilmour or Townshend, and I'm not a purist. That being said, I've rolled some tubes through mine with a mix of new production and NOS. no matter what I put in the amp, so long as it is quality and properly functioning, it pretty much sounds like itself. I haven't ever swapped a tube and had a drastic change. I've had that happen with other amps, but not this one. But here is what I have found that I like:

Preamp tubes: if I put all the same it tends to sound too much the same. I mix and match for balance. I think I currently have a GE long gray plate in V1, JJ long plate in V2, RI Mullard in V3, and a JJ short plate 12ax7 in the PI. I have some old Mullard 12AT7s for the PI and they sound great, but the JJ in the PI gives a little more compression and does something in the low mids that I like. RCA black plates sound really good in V1 as well. I've had an old Mullard and Brimar as well. They sounded good, but the clouds of heaven never opened up.

Power tubes: I've had a few different JJs, winged Cs, RI Mullard, and EHX, they all sounded good. Winged Cs were the best. Balanced tone and have a nice feel to them. I've had a tube failure with both the RI Mullard and the EHX. But only once each. I won't draw a conclusion on that. I'd probably buy JJ over RI Mullard. Not sure why.

An interesting and unexpected standout was a set of JJ 6v6s. They held up to the plate voltage and sounded great. Might put them back in there.
 

saltyj

Member
Messages
155
Thanks everyone! I ended up getting some RI mullards for power tubes for super cheap just to try. Prior were three random Peavey tubes a single Mesa tube so even these definitely sound better. Part of me wants to not crack open the amp to see what preamp tubes are in there currently to not buy into the hype but at the same time, I think when I do upgrade I’m willing to spend a bit more for the preamp tubes. Cool advice about mixing it up for preamp tubes, I’ll definitely try that out. Thanks!
 

fiveightandten

Silver Supporting Member
Messages
6,154
For new production, Svtelana EL34s are the only ones I’m aware of that are rated to take the screen voltage they’ll see in a DR103. Also, does a ‘77 have adjustable bias with aduquate range? You may need to have a tech mod the amp.

After owning a fairly large amount of different new production and NOS tubes, IMO the reason to buy NOS is service life, though that’s not always a guarantee.

Different tubes can sound different. Different tubes of the same maker and type can sound different due to current draw or gain variances. I’ve personally not experienced NOS tubes to sound “better” than current production on a whole, or any particular brand to sound “better” than others.

I have NOS Mullards, RFTs, Brimars, Telefunken, JAN Phillips, RCAs, and others. Yeah, they sound good. So do my Electroharmonix and JJs. My current main gigging amp is a 1965 Deluxe Reverb. I have a few $300 pairs of 6V6s that I bought to check out in it (and another Deluxe I have). I’m running JJs in both amps. Why? They sounded the best. The NOS 6V6s sit in their boxes.

In short, I wouldn’t sweat the decision too much, and the amount of money you spend on tubes doesn’t correlate to how good the amp sounds.
 

saltyj

Member
Messages
155
For new production, Svtelana EL34s are the only ones I’m aware of that are rated to take the screen voltage they’ll see in a DR103. Also, does a ‘77 have adjustable bias with aduquate range? You may need to have a tech mod the amp.

After owning a fairly large amount of different new production and NOS tubes, IMO the reason to buy NOS is service life, though that’s not always a guarantee.

Different tubes can sound different. Different tubes of the same maker and type can sound different due to current draw or gain variances. I’ve personally not experienced NOS tubes to sound “better” than current production on a whole, or any particular brand to sound “better” than others.

I have NOS Mullards, RFTs, Brimars, Telefunken, JAN Phillips, RCAs, and others. Yeah, they sound good. So do my Electroharmonix and JJs. My current main gigging amp is a 1965 Deluxe Reverb. I have a few $300 pairs of 6V6s that I bought to check out in it (and another Deluxe I have). I’m running JJs in both amps. Why? They sounded the best. The NOS 6V6s sit in their boxes.

In short, I wouldn’t sweat the decision too much, and the amount of money you spend on tubes doesn’t correlate to how good the amp sounds.

My tech mentioned something about the bias being modded or something of the sort and that any new production tube would suffice? He told me to just go for tung sols or mullard reissues. Wrong advice? He did say before bringing the amp that he’s not super knowledgeable about Hiwatt’s but he’s also a great tech.
 

fiveightandten

Silver Supporting Member
Messages
6,154
My tech mentioned something about the bias being modded or something of the sort and that any new production tube would suffice? He told me to just go for tung sols or mullard reissues. Wrong advice? He did say before bringing the amp that he’s not super knowledgeable about Hiwatt’s but he’s also a great tech.
Great, so it sounds like it’s had the bias mod done.

Tung Sol or Mullard reissues will probably be fine. But if you look at the spec sheets I believe they are under spec for the screen voltage. The Svetlana EL34s have a higher rating. That’s what I use in my old Orange heads and Hiwatt DR504, which have high B+ voltages. Though many people run tubes that are technically under spec in these amps, so it’s not likely to explode with Tung Sols or Mullards in it. I bought my Orange OR-80 loaded with Mullards and they were functioning fine.
 

saltyj

Member
Messages
155
Great, so it sounds like it’s had the bias mod done.

Tung Sol or Mullard reissues will probably be fine. But if you look at the spec sheets I believe they are under spec for the screen voltage. The Svetlana EL34s have a higher rating. That’s what I use in my old Orange heads and Hiwatt DR504, which have high B+ voltages. Though many people run tubes that are technically under spec in these amps, so it’s not likely to explode with Tung Sols or Mullards in it. I bought my Orange OR-80 loaded with Mullards and they were functioning fine.
When you say explode...do you mean the actual amp or just the tubes? You’re freaking me out, haha!
 

ProfRhino

Member
Messages
10,103
I'll only comment about tone alone, availability and price differs too much according to your location.
put those JJs, Sovteks, Shuguangs in modern amps - the Hiwatt will roll its eyes :rolleyes: and keep working, but it will not be amused. :puh

for vintage Hiwatts (mine are mid 70s), there is one tube recipe almost everyone would agree on in AB, that's the tubes they were designed around back then.
Mullard i6x ECC83, a Mullard ECC81 for PI (I prefer the CV4024 military version), and XFs for power tubes.
that's the magic bullet, trust me, no contest. :love:
if you have them (they are bloody rare), you can substitute Mullard long plates for an equally cool alternative option.
for all these tubes, the direct equivalents by Valvo (and some other Philips brands) are worthy alternatives (go by the etch codes, not by the printed labels).
there is one other preamp tube I enjoy in these amps, for even more bite while retaining the classic vibe, that's the Tungsram ECC83.
for power tubes, RFTs (regardless of label, look for the dimple top) are also legit.
that's about it, in a nutshell ...

two general pointers :
Hiwatt really built for Mullards, as the lack of bias adjustment shows.
if I would want to mod a Hiwatt for generic tubes (no, ma'am, mine remain stock :cool: ), I would go for separate bias pots per tube, eliminating the need for matched tube sets, which are mighty expensive).

keep in mind Hiwatt went to an ECC83 PI in the late 70s, for slightly more gain.
from what I have heard (but don't quote me on that), this involved a minor circuit change. So you better run the proper tube for your amp. :idea
that said, of course I tried an i63 in mine :p, but didn't like it as much as the CV4024, so it went back to stock.

all ime, imho, ymmv,
Rhino
 

JimmyBrungus

Member
Messages
178
I'll only comment about tone alone, availability and price differs too much according to your location.
put those JJs, Sovteks, Shuguangs in modern amps - the Hiwatt will roll its eyes :rolleyes: and keep working, but it will not be amused. :puh

for vintage Hiwatts (mine are mid 70s), there is one tube recipe almost everyone would agree on in AB, that's the tubes they were designed around back then.
Mullard i6x ECC83, a Mullard ECC81 for PI (I prefer the CV4024 military version), and XFs for power tubes.
that's the magic bullet, trust me, no contest. :love:
if you have them (they are bloody rare), you can substitute Mullard long plates for an equally cool alternative option.
for all these tubes, the direct equivalents by Valvo (and some other Philips brands) are worthy alternatives (go by the etch codes, not by the printed labels).
there is one other preamp tube I enjoy in these amps, for even more bite while retaining the classic vibe, that's the Tungsram ECC83.
for power tubes, RFTs (regardless of label, look for the dimple top) are also legit.
that's about it, in a nutshell ...

two general pointers :
Hiwatt really built for Mullards, as the lack of bias adjustment shows.
if I would want to mod a Hiwatt for generic tubes (no, ma'am, mine remain stock :cool: ), I would go for separate bias pots per tube, eliminating the need for matched tube sets, which are mighty expensive).

keep in mind Hiwatt went to an ECC83 PI in the late 70s, for slightly more gain.
from what I have heard (but don't quote me on that), this involved a minor circuit change. So you better run the proper tube for your amp. :idea
that said, of course I tried an i63 in mine :p, but didn't like it as much as the CV4024, so it went back to stock.

all ime, imho, ymmv,
Rhino

He speaks the truth. Mullard cv4024 for pi. I had little trouble saving the rest of the vintage glass and running JJs for the rest of the positions.
 

fiveightandten

Silver Supporting Member
Messages
6,154
When you say explode...do you mean the actual amp or just the tubes? You’re freaking me out, haha!
Haha, I was being facetious. It's just a point to consider and be educated on. I believe the B+ voltage spec for your amp is ~460V. However, modern wall voltage is higher than what the amp was designed for, making the internal voltages higher. It may be running closer to 500V, but surely higher than 460V (screen voltage is usually very close to full B+/plate voltage).

So, if you go with current production tubes, their max voltage rating for the screen grid is typically under what the amp will subject them to. Svetlana EL-34s are the exception, as they're rated at 500V.

Svetlana - 500V

Electro Harmonix - 425V

Tung Sol - 425V

JJ - 450V
 

Echoplexi

Gold Supporting Member
Messages
12,230
Haha, I was being facetious. It's just a point to consider and be educated on. I believe the B+ voltage spec for your amp is ~460V. However, modern wall voltage is higher than what the amp was designed for, making the internal voltages higher. It may be running closer to 500V, but surely higher than 460V (screen voltage is usually very close to full B+/plate voltage).

So, if you go with current production tubes, their max voltage rating for the screen grid is typically under what the amp will subject them to. Svetlana EL-34s are the exception, as they're rated at 500V.

Svetlana - 500V

Electro Harmonix - 425V

Tung Sol - 425V

JJ - 450V

Thats one reason why I went with Svetlanas for my 504. Kind of a letdown, when pushed to overdrive, compared to the XF2s that were in there before, but not bad.


Anos Mullard I63 in V1, KT88’s for output tubes. Absolutely Awesome!! You will have to lower the bias dropping resistor in the bias section for the KT88’s but bias them at 26 watts dissipation each.

I would love to hear what a pair of KT88s would sound like in my 504.
 

VICOwner

Gold Supporting Member
Messages
2,576
Thats one reason why I went with Svetlanas for my 504. Kind of a letdown, when pushed to overdrive, compared to the XF2s that were in there before, but not bad.




I would love to hear what a pair of KT88s would sound like in my 504.
They make EL34’s sound thin. The KT88’s make the amp bigger with no loss anywhere. In a DR103, the rest of the band can can sit with the audience, you’ll be able to cover all the bases.
 

sixty2strat

Member
Messages
12,561
When I first gotmy Dr103it was eating powertubes like crazy, badscreen resistor clueless techs. I can't afford vintage 34's so had JJ mullard and GTduring this process. I thought the mullards sounded best but had the most issues. I did swap preamp but thought Bugleboys were best, but not by much, even the JJ sounded good. The one thing that really helped the sound was the speakers. I tried to find a vintage cab, most were 3k or a box of excuses and issues or local pickup in TX . So used EVSRO, Emi Tonker and a range of celestion newandvintage from alnicon to G1275. Only when I got a Hitone cab did it come together.
 




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